ArticlePDF AvailableLiterature Review

Land Use for Edible Protein of Animal Origin—A Review

Authors:

Abstract and Figures

The present period is characterized by a growing world population and a higher demand for more and better quality food, as well as other products for an improved standard of living. In the future, there will be increasingly strong competition for arable land and non-renewable resources such as fossil carbon-sources, water, and some minerals, as well as between food, feed, fuel, fiber, flowers, and fun (6 F’s). Proteins of animal origin like milk, meat, fish, eggs and, probably, insects are very valuable sources of essential amino acids, minerals and vitamins, but their production consumes some non-renewable resources including arable land and causes considerable emissions. Therefore, this study´s objective was to calculate some examples of the land use (arable land and grassland) for production of edible animal protein taking into consideration important animal species/categories, levels of plant and animal yields, the latter estimated with and without co-products from agriculture, and the food/biofuel industry in animal feeding. There are large differences between animal species/categories and their potential to produce edible protein depending on many influencing variables. The highest amounts per kilogram body weight are produced by growing broiler chicken followed by laying hens and dairy cows, the lowest yields in edible protein and the highest land need were observed for beef cattle. This review clearly indicates that the production of food of animal origin is a very complex process, and selective considerations, i.e., focusing on single factors, do not provide an assessment that reflects the complexity of the subject.
Content may be subject to copyright.
animals
Review
Land Use for Edible Protein of Animal
Origin—A Review
Gerhard Flachowsky 1, Ulrich Meyer 1, * and Karl-Heinz Südekum 2
1
Institute of Animal Nutrition, Friedrich-Loeffler-Institut (FLI), Federal Research Institute for Animal Health,
38116 Braunschweig, Germany; gerhard.flachowsky@fli.de
2Institute of Animal Science, University of Bonn, 53115 Bonn, Germany; ksue@itw.uni-bonn.de
*Correspondence: ulrich.meyer@fli.de; Tel.: +49-531-58044-137
Academic Editor: Frank Mitloehner
Received: 16 December 2016; Accepted: 13 March 2017; Published: 18 March 2017
Simple Summary:
The growing world population has led to a higher demand for more and better
quality food. In the future, there will be increasingly strong competition for arable land and other
non-renewable resources. Proteins of animal origin are very valuable sources of essential nutrients,
but their production consumes resources and causes emissions. The aim of this study was to calculate
exemplarily the land use for production of edible animal protein from different animal species and
categories in consideration of important influencing factors. Large differences were found with the
highest amounts per kilogram of body weight produced by broiler chickens and the lowest yields in
edible protein and the highest land need observed for beef cattle.
Abstract:
The present period is characterized by a growing world population and a higher demand for
more and better quality food, as well as other products for an improved standard of living. In the future,
there will be increasingly strong competition for arable land and non-renewable resources such as
fossil carbon-sources, water, and some minerals, as well as between food, feed, fuel, fiber, flowers,
and fun (6 F’s). Proteins of animal origin like milk, meat, fish, eggs and, probably, insects are very
valuable sources of essential amino acids, minerals and vitamins, but their production consumes
some non-renewable resources including arable land and causes considerable emissions. Therefore,
this study
´
s objective was to calculate some examples of the land use (arable land and grassland)
for production of edible animal protein taking into consideration important animal species/categories,
levels of plant and animal yields, the latter estimated with and without co-products from agriculture,
and the food/biofuel industry in animal feeding. There are large differences between animal
species/categories and their potential to produce edible protein depending on many influencing
variables. The highest amounts per kilogram body weight are produced by growing broiler chicken
followed by laying hens and dairy cows; the lowest yields in edible protein and the highest land
need were observed for beef cattle. This review clearly indicates that the production of food of animal
origin is a very complex process, and selective considerations, i.e., focusing on single factors, do not
provide an assessment that reflects the complexity of the subject.
Keywords:
food security; human-edible protein; land use; arable land; grassland; plant yield;
animal yield; co-products
1. Introduction
Food security is currently a pivotal phrase. Food security means meeting the demand of a growing
world population for food of plant and animal origin. The FAO (Food and Agriculture Organization of
the United Nations) [
1
] defined food security as “access to sufficient, safe, nutritious food to maintain
a healthy and active life”. This, in turn, is associated with a growing demand for limited natural
Animals 2017,7, 25; doi:10.3390/ani7030025 www.mdpi.com/journal/animals
Animals 2017,7, 25 2 of 19
resources such as land area, fuel, water, and minerals, and with elevated emissions of gases including
greenhouse gas (GHG) potential such as carbon dioxide (CO
2
), methane (CH
4
), nitrous oxide (N
2
O),
and other substances (e.g., nitrogen, phosphorus, trace elements).
At the end of October 2011, the seven billionth person was born. Sustainability in feed and food
production is a key challenge for agriculture as summarized recently in articles and monographs
(e.g., [
2
6
]). In the future, there will be strong competition for arable land and non-renewable resources
such as fossil carbon-sources, water [
7
9
], and some minerals such as phosphorus [
10
,
11
]. There will
also be competition for land use between feed, food, fuel, fiber, flowers, and fun (6 F’s concept; [
12
]),
as well as between areas for settlements and natural protected areas.
The balance between Planet (global resources and emissions), People (population all over the
world with adequate nutrition and social conditions), and Profit (money-making) in the so-called
3P-concept [
7
,
13
] is an important prerequisite for sustainable life and development on the earth.
Profit should not be the single objective of production. We have to find a balance between a careful
and sustainable use of limited resources on the one hand and low emissions with minimal local and
global consequences for later generations on the other hand.
According to the FAO [
14
,
15
], the human population will increase globally from above seven
billion currently to more than nine billion people in 2050, but the increase in the output of food of
animal origin is estimated to be about 70% [
16
]. Therefore, some authors propose a redefinition and
a rethinking of agricultural yield, and agriculture in general, from tons per hectare to people per
hectare [
17
,
18
] and increasingly demand sustainable animal agriculture [
19
]. The energy and protein
conversion efficiency from feed into food of animal origin is low and may range from 3% (energy—beef)
up to 40% (energy—dairy; protein—chicken for fattening) [
18
,
20
]. In some countries (e.g., USA)
between 67% (energy) and 80% (protein) of the crops are used as animal feed [
18
]. Feedstuffs such as
grass and other roughage which cannot directly be consumed by humans, co-products of agriculture
and of the food and biofuel industry may also contribute to a more efficient production of food of
animal origin. Especially with regard to ruminants, less potential human food should be fed to animals
in order to improve the proportion of protein output by animals relative to protein input [21].
These developments and complex connections present the following question: “Is there any need
for food of animal origin?” As some population groups (e.g., vegans) demonstrate, there is no essential
need for food of animal origin, but the consumption of meat, fish, milk, and eggs may contribute
significantly to meeting the human requirements of amino acids [
22
24
] as well as some important trace
nutrients (such as Ca, P, Zn, Fe, I, Se, and vitamins A, D, E, B
12
), especially for children and juveniles
as well as pregnant and lactating women [
25
,
26
]. Human nutritionists [
27
,
28
] have recommended that
about one third of the daily protein requirement (0.66–1g per kg body mass [
22
,
29
]) should originate
from protein of animal origin. Consequently, about 20 g of the daily intake of about 60 g protein [
30
]
should be of animal origin, which is lower than the present average consumption throughout the
world. Presently, there is an average consumption of animal protein (without fish and insects) of about
24 g per capita and day, ranging from 1.7 (Burundi) to 69.0 g (USA; Table 1). It is difficult to assess the
protein intake from fish. Avadi and Freon [31] estimate that half of the world´s population consumes
at least 15% of their animal protein from aquaculture.
Other reasons for consumption of food of animal origin are the high bioavailability of most
nutrients and their considerable enjoyment value. Such food is also considered to be an indicator of
standard of living in many regions of the world, and it is also determined by taste, odor, and texture,
as well as by geographic area, culture, ethics, and wealth. Further reasons for the higher demand
of food of animal origin in some countries are the increased income of the population [
32
] and the
imitation of the so-called “Western style of life”. Many developing countries continue to consume
more animal products than they produce. Therefore, they will continue to drive the world demand for
all agricultural products, including food of animal origin [
33
,
34
]. Wu et al. [
34
] estimated that with
exponential growth of the global population and marked rises in meat consumption, demands for
animal-source protein will increase by 72% between 2013 and 2050. Greater amounts of food of animal
Animals 2017,7, 25 3 of 19
origin require greater plant yields and/or more area for feed production, more animals and/or higher
animal yields, and an increase in agricultural trade.
Table 1.
Intake of milk, meat, and eggs as well as protein of animal origin per capita and year
1
and
portion (%) of total protein intake (global minimum-values; maximum-values and averages, as well as
German values for comparison; kg per capita and year: data base 2005; [15].
Food Minimum Average Maximum
Milk (kg per year) 1.3
(Kongo) 82.1 367.7
(Sweden)
Meat 2(kg per year) 3.1
(Bangladesh) 41.2 142.5
(Luxembourg)
Eggs (kg per year) 0.1
(Kongo) 9.0 20.2
(China)
Edible protein of animal origin
(g per capita and day)
1.7
(Burundi) 23.9 69.0
(USA)
Portion of animal protein as % of
total protein intake per capita
4.0
(Burundi) 27.9 59.5
(USA)
1
Total daily protein intake per person: Burundi 42.5 g, global average 85.7 g, USA 116.0 g;
2
Presumptive empty
body weight (meat plus bones).
On the other hand, changing the eating patterns [
35
] and eating fewer or no livestock products,
especially meat, is a possible solution to reduce the environmental impact of animal agriculture [
36
38
]
and to reduce the per capita land requirements [39,40].
Apart from resource needs, feed and food production causes emissions with a certain greenhouse
gas (GHG) potential, such as carbon dioxide from fossil fuel (greenhouse gas factor (GHF) = 1),
methane (GHF about 23) from enteric fermentation, especially in ruminants, and from excrement
management, as well as nitrogen compounds (NH
3
and N
2
O, GHF about 300; [
41
]) from protein
metabolism in the animals [
19
,
24
,
42
44
]. Apart from a lower input of limited resources along the
food chain, a low output of GHG, summarized as carbon footprints (CF) and expressed as carbon
dioxide equivalents (CO
2
-eq), and minerals such as phosphorus and some trace elements during feed
and food production are very important aims of sustainable agriculture. Presently, about 14.5% of
total human-induced global emissions, estimated at 7.1 Gt CO
2
-eq annually, come from the global
production of food of animal origin [
45
]. Therefore, as underlined by some authors [
43
,
46
,
47
], more
attention should be given to optimizing animal breeding [
19
,
48
] and animal health, reducing animal
losses, and developing low-emission diets using life cycle assessments (LCA) for all societies [49,50].
Land, especially arable land, is one of the most important limiting factors [
51
]. Only a small portion
of the approximately 13.4 billion ha global surface is available as arable land (about 1.5 billion ha,
or about 12% of the world’s land area [
24
,
52
]). This area could be extended to a degree (by about
120 million ha [
24
,
52
]), but some areas cannot be used because of limited water resources, forests,
urban settlements, environmental protection, deserts, mountains, and other factors. As a result of the
finite area of arable land and the increase in population, the area of arable land available per person
decreased from about 0.45 ha (1960) to about 0.25 ha (2010) and will further decrease to below 0.20 ha
per person after 2020 (Figure 1).
This situation and the increasing use of land for biofuel production [
53
], organic farming,
settlements, natural protected areas, and other purposes has consequences for feed and food production.
Because of the high need for limited resources, attention has been paid to the space needed for
animal production. Some authors have considered the land use, also described as land or area
footprint, for food of animal origin [
38
,
39
,
54
56
]. These authors proposed to distinguish between areas
(mostly arable land) that can also be used for purposes other than for feed production (6 F-concept:
food, feed, fuel, fiber, flowers, and fun) and typical feed areas (grassland or perennial crops).
Animals 2017,7, 25 4 of 19
Reynolds et al. [26]
analyzed the importance of animals in agricultural sustainability and food security.
Grassland and co-products of agriculture, food, and the biofuel industry do not need arable land and,
thus, do not contribute to food-feed competition between animals and humans. The human-edible
feed conversion efficiency (heFCE) [
57
,
58
] is defined as human-edible output via the animal products
(e.g., edible protein) divided by the potentially human edible input via feedstuffs and may contribute to
the calculation the feed need without competition to human nutrition. Van Zanten et al. [
59
] proposed
the calculation of land use efficiency of livestock systems to address the contribution of livestock to the
global food supply.
Animals 2017, 7, 25 4 of 19
animal products (e.g., edible protein) divided by the potentially human edible input via feedstuffs
and may contribute to the calculation the feed need without competition to human nutrition. Van
Zanten et al. [59] proposed the calculation of land use efficiency of livestock systems to address the
contribution of livestock to the global food supply.
Figure 1. Development of world population compared to arable land per inhabitant between 1960
and 2020 [52].
There is no reason to believe that the public interest in the use of limited resources and the high
emissions (i.e., CF) from the production of food of animal origin will diminish in the near future
because of the worldwide increase in land need and emissions. Therefore, the objectives of this paper
are (1) to make some model calculations for the land use and to propose land footprints (LF) for
production of food of animal origin, measured per product unit and/or as edible protein and (2) to
compare the data with selected references. Furthermore, some calculations to compare human-edible
protein output via food of animal origin with edible protein input are done.
Such data could be considered as a starting point for calculations of land use per inhabitant and
year (or lifespan), depending on, for example, the amount of protein consumption, protein sources,
and levels of plant and animal yields. Average values for plant and animal yields were used and
demonstrated the model character of present calculations. In the future, more details should be
considered to help determine the possible or necessary intensity level for feed and animal production
in order to have an available amount of food of animal origin for human beings. Alternatives to the
production of food of animal origin with minimal use of arable land, and with consideration of
grassland and co-products from agriculture and the food and fuel industries, should also be
considered.
The structure of this article is a combination of a review and author-based calculations, for which
references were selected based on presumed particular relevance in the context of the issues
discussed in this study A thorough review would have had the major message that previous attempts
to estimate land use for edible protein of animal origin had used very diverse variables and factors
making sound conclusions impossible. For the same reason, a meta-analysis using an appropriate
statistical model could not be performed because different authors used different definitions for the
same term, and published data did not allow converting data to a common denominator. Without
this, however, a meta-analysis would have been subject to erroneous results.
2. Materials and Methods
2.1. Estimation of Human-Edible Fractions of Feeds
Food-producing animals, especially non-ruminants, consume plant protein which is also edible
by humans. Therefore, the proportion between edible protein input by animals and the output as
Figure 1.
Development of world population compared to arable land per inhabitant between 1960 and
2020 [52].
There is no reason to believe that the public interest in the use of limited resources and the high
emissions (i.e., CF) from the production of food of animal origin will diminish in the near future
because of the worldwide increase in land need and emissions. Therefore, the objectives of this paper
are (1) to make some model calculations for the land use and to propose land footprints (LF) for
production of food of animal origin, measured per product unit and/or as edible protein and (2) to
compare the data with selected references. Furthermore, some calculations to compare human-edible
protein output via food of animal origin with edible protein input are done.
Such data could be considered as a starting point for calculations of land use per inhabitant
and year (or lifespan), depending on, for example, the amount of protein consumption, protein
sources, and levels of plant and animal yields. Average values for plant and animal yields were used
and demonstrated the model character of present calculations. In the future, more details should be
considered to help determine the possible or necessary intensity level for feed and animal production
in order to have an available amount of food of animal origin for human beings. Alternatives to
the production of food of animal origin with minimal use of arable land, and with consideration of
grassland and co-products from agriculture and the food and fuel industries, should also be considered.
The structure of this article is a combination of a review and author-based calculations, for which
references were selected based on presumed particular relevance in the context of the issues discussed
in this study A thorough review would have had the major message that previous attempts to estimate
land use for edible protein of animal origin had used very diverse variables and factors—making
sound conclusions impossible. For the same reason, a meta-analysis using an appropriate statistical
model could not be performed because different authors used different definitions for the same term,
and published data did not allow converting data to a common denominator. Without this, however,
a meta-analysis would have been subject to erroneous results.
Animals 2017,7, 25 5 of 19
2. Materials and Methods
2.1. Estimation of Human-Edible Fractions of Feeds
Food-producing animals, especially non-ruminants, consume plant protein which is also edible
by humans. Therefore, the proportion between edible protein input by animals and the output as food
of animal origin are questioned (e.g., [
18
,
36
,
39
]). The human edible feed conversion efficiency (heFCE)
can be calculated on the base of human-edible output in the form of animal products divided by
potential human-edible input [
57
,
58
]. Such calculations can be done for edible protein (heP; see Table 2)
of feed, but also for edible energy (heE). The data shown in Table 2are used to calculate the heFCE.
Wilkinson [
57
] proposed values for the calculation of heFCE of rations for human-edible energy (heE)
and human-edible protein (heP): 80% for cereal grains, pulses, and soybean co-products; 20% for wheat
bran, sunflower, and rapeseed co-products and no heE/P (i.e., 0%) for grass, silages, and all other
co-products. Some values applied by Wilkinson [
57
] are disputable (e.g., for maize silage), because the
feeds are produced on arable land, which could alternatively be used for cultivation of plants with
high human-edible fractions (hef).
Table 2.
Crude protein content of some feeds [
60
] and their human-edible fraction (hef; in %) (taken
from Wilkinson [57]) and for three different estimation scenarios from Ert et al. [58].
Feedstuff Crude Protein
(g/kg DM 3)
Hef-Fractions
(% of CP)
Hef-Fractions (% of CP 2)
Low Medium High
Barley 125 80 40 65 80
Maize 106 80 70 80 90
Wheat 138 80 60 80 100
Soybeans 404 80 50 92 93
Rapeseed meal 406 20 30 59 87
Soybeans meal 513 80 50 71 92
Wheat bran 160 20 0 10 20
Maize silage 86 0 19 29 45
Others 10 0 0 0
1
Other co-products (e.g., sugar beet pulp; brewer’s grains; dried distiller’s grains with solubles, etc.) and roughages
(e.g., fresh grass; silages, hay etc.); 2Crude protein; 3Dry matter.
Some authors (e.g., [
21
,
22
,
52
]) consider the quality and digestibility of potentially human-edible
inputs (plant protein) to describe the nutritional value of proteins as the protein quality ratio (PQR).
Such calculations are based on the limiting amino acid in dietary protein, divided by the same
amino acid of the reference protein [
61
] or further derived equations [
24
,
52
]. This approach adds
further quality but also complexity to the estimation of heP which can make comparisons across
sources difficult.
2.2. Edible Fraction and Protein Content of Animal Products
The production of protein of animal origin is one of the most important goals of animal
husbandry [
5
,
38
,
55
]. Edible protein can be used to compare the efficiency of animal production
(e.g., milk, meat, eggs) and to assess the emissions per product [62].
Quantification of protein yield varies depending on some influencing factors. For example, milk
and eggs are clearly defined as food of animal origin and the yield can be measured (and expressed
as kg or L per animal or per day), and, therefore, it is relatively easy to use the yield of lactating and
laying animals for further calculations. The edible fraction of milk and eggs is almost 100% of the yield.
Only minor fractions are not consumed by humans (e.g., colostrum, milk samples at the beginning of
milking, egg membranes, and shells), which are not considered in further calculations (Table 3).
Animals 2017,7, 25 6 of 19
It is much more difficult to quantify and characterize the yield from the animal body after
slaughtering and processing. The following endpoints can be measured in the case of animals for
meat production:
Weight gain of the animal (per day or per growing period) during the whole life span
Weight gain of the animal without gastro-intestinal tract contents
Empty body mass (or carcass weight; meat and bones; warm or cold)
Meat (empty body mass minus bones)
Edible fraction (meat plus edible organs and tissues)
Edible protein (edible fractions of the carcass multiplied by their specific protein content)
Mostly, the term “meat” is used, but sometimes what is exactly meant by this term is not clearly
described (meat with or without bones). Peters et al. [
63
] introduced the term “hot standard carcass
weight” (HSCW) as the weight at the exit gate of the meat processing plant. The FAO [
24
] defines
meat from animals as fresh, chilled, or frozen meat with bones. The FAO data on meat are given in
terms of dressed carcass weight excluding offals and slaughter fats. The HSCW varies between 50%
and 62% of the live weight of cattle before slaughter, but it may vary between 50% in the case of
sheep up to 80% for turkeys [
38
,
42
,
63
,
64
]. Nijdam et al. [
38
] used the following killing-out percentages
(carcass weight as a percent of live weight): 53% for beef, 75% for pork, 46% for mutton, 70% for
poultry, and 40% for fish. The edible meat yield (retail meat of carcass), given by the same authors, is:
70% for beef, 75% for pork and mutton, 80% for poultry, and 100% for fish.
When it comes to the definition of “edible” fractions, large differences exist between countries, and
also between population groups within one country. Therefore, it is difficult to compare results from
various authors and to find out the actual protein yields. Regardless of the method used for calculations
of edible fractions, authors should always clearly describe how values were used and derived to allow
understanding and interpretation of results [
63
]. Another important factor for a reliable calculation of
protein yields of food of animal origin is the protein content of edible fractions as shown in Table 3.
Table 3.
Protein content of some edible land animal products/food by various authors (in g per kg
edible product).
Product/Food Authors Milk (Cows) Beef Pork Poultry Eggs
Flachowsky [65] 34 190 150 200 120
GfE 1[6669]34 170–200 157
(129–178) n.d. 2121
(110–124)
Souci et al. [70]33.3
(30.8–37.0)
220 3
(206–227)
220 3
(195–240) 199 125
De Vries and de Boer [55] 30 190 190 190 130
Mekonnen and Hoekstra [71] 33 138 105 127 111
Andersen [72] 34 206–212 183–216 182–242 125
Lesschen et al. [73]434.4 206 156 206 119
Nijdam et al. [38] 35 200 200 200 130
USDA [74] 34 173 139 186 126
1Gesellschaft für Ernährungsphysiologie; 2no data; 3Muscles only; 4N-content x 6.25.
The results of specific studies (Table 3) as well as values from food tables [
70
,
74
] are, overall,
in agreement regarding the ranges of protein content in animal-based food: milk (between 30.8 and
37.0 g/kg), beef (170–227 g/kg), pork (129–240 g/kg), poultry meat (182–242 g/kg), and eggs
(110–130 g/kg). Much lower values for beef, pork, and poultry were used by [
71
] to calculate water
footprints for food of animal origin, resulting in very high values for some foods of animal origin
Animals 2017,7, 25 7 of 19
(e.g., [
71
,
75
]). The protein yield in the edible fractions of milk, meat, and eggs was calculated based on
our previous assumptions and data [65] (Table 3).
2.3. Animal Performances/Yields
Apart from the edible fractions and the protein content of edible fractions, the protein yield
per animal and day is also influenced by animal species and categories and by animal performance.
Table 4summarizes data about the animal species/categories and the performance of animals regarding
their expected yield of edible protein. This paper will consider edible protein of animal origin as the
main objective of animal husbandry. Furthermore, it is also easier to compare animal yields of various
forms of animal production based on animal protein yield [38,55,62].
Table 4.
Influence of animal species, categories, and performances on yield of edible protein
(without considering rearing periods and animal losses) [62,65].
Protein Source
(Body Mass)
Performance
(per d)
Dry
Matter
Intake
(kg per d)
Forage to
Concentrate
Ratio
(%, DM Basis)
Edible
Fraction
(% of Product
or Body Mass)
Protein in
Edible
Fraction
(g per kg)
Edible
Protein
Yield
(g per d)
Edible Protein
Yield
(g per kg Body
Mass and d)
Dairy cow
(650 kg)
2 kg milk
5 kg milk
10 kg milk
20 kg milk
40 kg milk
8
10
12
16
25
100
95/5
90/10
75/25
50/50
95 34
67
163
323
646
1292
0.1
0.25
0.5
1.0
2.0
Dairy goat
(60 kg)
0.5 kg milk
1 kg milk
2 kg milk
1
1.5
2
100
90/10
80/20
95 36
17
34
68
0.3
0.55
1.1
Beef cattle
(350 kg)
200 g ADG 1
500 g ADG
1000 g ADG
1500 g ADG
6.0
6.5
7.0
7.5
100
95/5
85/15
70/30
50 190
19
48
95
143
0.05
0.14
0.27
0.41
Growing/fattening
pig
(80 kg)
200 g ADG
500 g ADG
700 g ADG
1000 g ADG
1.5
1.8
2
2.2
30/70
20/80
10/90
0/100
60 150
18
45
63
90
0.22
0.56
0.8
1.1
Chicken for
fattening
(1.5 kg)
20 g ADG
40 g ADG
60 g ADG
0.06
0.07
0.08
15/85
10/90
0/100
60 200
2.4
4.8
7.2
1.6
3.2
4.8
Laying hen
(1.8 kg)
20% LP 2
50% LP
70% LP
90% LP
0.09
0.10
0.11
0.12
30/70
20/80
10/90
0/100
95 120
1.4
3.4
4.8
6.2
0.8
1.9
2.7
3.4
1Average daily gain; 2Laying performance.
The highest protein yields per kg body mass are from intensively produced growing and laying
poultry, followed by lactating ruminants and pigs. Growing ruminants (e.g., beef cattle, suckler calves)
show the lowest protein yield per kg body mass and day (Table 4). Table 4only shows data of animals
in the production phase. Yet, animal production is more complex and for more detailed and reliable
calculations, the breeding/reproduction phase should also be considered. If these phases are taken into
account, yields are lower and it also becomes evident that impaired reproduction or fertility—often
caused by poor nutrition and (or) diseases—is a major obstacle to more efficient resource use by
food-producing animals.
2.4. Plant Yields on Grassland (Perennial Crops) and on Arable Land
Apart from animal performance, information on plant yields should also be available for land use
calculations. The need for arable land is influenced by various factors such as
Type of forage and crops from arable land and their yields
Losses during harvest, preservation, and storage
Animals 2017,7, 25 8 of 19
Consideration of co-products of agriculture, food, and biofuel industries (such as straw,
solvent-extracted oilseed meals, dried distiller’s grains with solubles (DDGS) in animal nutrition)
Animal species and categories, number of animals, and animal yields
Diet composition; forage-to-concentrate ratio
The easiest way to incorporate plant yields is to calculate the land use on the basis of dry matter
(DM) yields, but a more specific characterization of feed (e.g., consideration of various plant species,
digestibility, protein yield, or energy yield expressed as digestible, metabolizable, or net energy) would
be helpful for a more accurate assessment. Energy and nutrient requirements for all food-producing
animals including horses across a wide range of performance levels can be found in documents from
the National Research Council of the USA (e.g., for dairy cattle: [
76
]) or in the recommendations of the
Society of Nutrition Physiology in Germany [6669,77].
Three intensity levels (A—low, B—medium, and C—high) for plant yields on grassland
(perennial crops = roughage) and for arable land (cultivated crops = concentrate) were assumed for
further model calculations (Table 5). Low, medium, and high yield levels were considered. The assumed
plant yields (Table 6) were selected to show the influence of yield on the land needed per unit of animal
product. Higher plant yields are an important prerequisite for solving global nutrition problems [78].
Another point especially significant for ruminants is the digestibility or the feed value of roughage,
especially if grown under tropical conditions. Such climatic conditions are expected to result in
forage of low nutritive value and a high proportion of protective structures containing cellulose,
hemicelluloses, lignin, cutin, and other structural substances such as silica [
79
]. Tropical forage,
therefore, often has a low nutritive value and a high proportion of protective structures to protect
the plant against predation, i.e., herbivory. Additional factors, e.g., long warm nights promoting
respiration, warmer growth temperatures increasing lignification, and specific types of grasses in
the tropics (mostly C4-plants) are also responsible for the lower nutritive value of tropical plants.
As an example, the average digestibility of the dry matter of grass/legume mixtures as given by the
FAO [
24
] is 75% for Europe and 64% for Africa, and for conserved grass/legume mixtures, the values
are 71% for Europe and 54% for Africa. More country- and feed-specific values are available in specific
feed value tables (e.g., [80,81]).
In tropical areas, free ranging animals, mainly ruminants (e.g., cattle, goats, sheep, and deer),
consume grassland. They are able to select feed according to their preference [
82
] and may substantially
contribute to supplying food of animal origin under such conditions. No limited resources, such as
arable land and fuel, nor extra water supply, are needed for these animals. Future studies should
consider the plant yields (Table 6), the nutritive value of grassland and perennial crops, the methods for
increasing feed value by intensified plant breeding or the improvement in post-harvest methods before
and during storage, and the assessment of consumption of such feeds by ruminants. Lower plants
yields and variation in digestibility and feed intake should also be analyzed as they are additional
influencing factors on animal yields under tropical conditions.
In the present paper, further calculations were made taking into consideration the yields for
forage and concentrates (Table 6) grown under the same yield levels; however, in reality, it is also
possible to harvest forage with yield level B and concentrates with yield level C, or to import feeds from
regions with lower or higher yields. The significance of co-products for animal feeding is described
in Section 2.5.
Table 5. Assumed plant yields for further calculations (kg dry matter per ha and year).
Yield Level Grassland or Perennial Crops
(Roughage)
Arable Land or Cultivated Crops
(Concentrate)
A (low) 5000 2000
B (medium) 10,000 5000
C (high) 20,000 10,000
Animals 2017,7, 25 9 of 19
Table 6.
Model calculations for land use per kg of edible protein depending on animal
species/categories, plant yields, and animal performances (for forage to concentrate ratio see Table 4;
all concentrates from arable land, no co-products considered).
Protein Source Animal
Yield
Edible Protein Yield
(g/d)
Grassland or Perennial Crops
(m2/kg Protein) 1
Arable Land or Cultivated Crops
(m2/kg Protein)
A2B C A B C
Cow milk 2 kg per d 67 240 120 60 0 0 0
5 kg per d 163 120 60 30 15 6 3
10 kg per d 323 70 35 18 18 8 4
20 kg per d 646 38 20 9 30 12 6
40 kg per d 1292 20 10 5 50 20 10
Goat milk 0.5 kg per d 17 120 60 30 0 0 0
1 kg per d 34 80 40 20 22 9 5
2 kg per d 68 50 25 13 30 12 6
Beef 200 g ADG 319 630 315 160 0 0 0
500 g ADG 48 260 130 65 35 15 7
1000 g ADG 95 125 60 30 55 22 11
1500 g ADG 143 75 40 20 80 30 15
Pork 200 g ADG 18 50 25 12 300 120 60
500 g ADG 45 16 8 4 160 65 32
700 g ADG 63 8 4 2 140 55 28
1000 g ADG 90 0 0 0 120 50 24
Chicken meat 20 g ADG 2.4 8 4 2 100 4 20
40 g ADG 4.8 3 2 1 65 25 13
60 g ADG 7.2 0 0 0 60 25 12
Eggs 20% LP 41.4 40 20 10 220 90 45
50% LP 3.4 12 6 3 110 50 25
70% LP 4.8 5 2 1 100 40 25
90% LP 6.2 0 0 0 95 40 20
1
Some authors (e.g., [
63
]) calculated this without perennial crops in non-ruminant (pigs and poultry) feeding;
2Plant yields: Levels A (low), B (medium), and C (high); see Table 5;3Average daily gain; 4Laying performance.
Ruminants generally do not require grains or other concentrates because the microbial population
in the rumen is capable of digesting plant fiber and, after fermentation of the released sugars, delivers
energy to the ruminant animal. Ruminants are, therefore, able to produce edible protein of animal
origin (milk and meat) from permanent meadows and pastures. They are enabling a net output
of human edible protein and may contribute to meeting the human needs for food of animal origin
(e.g., [
83
85
]). Kratli et al. [
86
] pointed out that pastoralists are more efficient at producing food per unit
area of dryland than other forms of agricultural land use under the same conditions. Pastoralist systems
are also efficient users of resources such as manure [
87
]. Because of the high fiber content of forage
from grassland and the low animal yields, methane emissions and the CF per kg of edible protein may
be higher under such extensive conditions [
24
,
88
] and GHG mitigation measurements are, therefore,
very important [
43
45
,
89
]. On the other hand, it should be considered that permanent grassland has
a quantitatively significant potential for soil carbon sequestration [90,91].
2.5. Significance of Co-Products
Apart from roughages and grains, co-products from agriculture (e.g., [
60
,
92
,
93
]), food
production [
60
,
94
], and the biofuel-industry [
95
] are commonly used as animal feeds. Co-products
are by-products of main processes such as grain production (e.g., straw, stalks, husks) and processing
of raw products in the food industry (e.g., solvent-extracted oilseed meals from the vegetable oil
industry, bran from cereal grain processing, beet pulp or bagasse from the sugar industry, and animal
co-products from milk, fish, or meat processing) or from the biofuel industry (e.g., DDGS, rape seed
cake and meal, as well as cakes and meals from other oilseeds). According to the FAO [
24
], between 10%
and 50% of the estimated concentrate feed comes from co-products in various global regions [
96
].
In some countries, up to 100% of concentrate may be co-products.
Animals 2017,7, 25 10 of 19
Co-products are used in various amounts and proportions in animal diets. Cereal straws and
other co-products rich in plant cell-walls are mostly characterized by a low digestibility and are, thus,
poor in energy and protein delivery. They are fed to ruminants with low animal yields or just to meet
their maintenance requirements. For high yielding ruminants, they can only be considered as a source
of fiber. Normally, they are not used in the feeding of non-ruminants.
In co-products from the food and fuel industry, the concentration of those nutrients not used
for processing is two to three times higher than that found in the original product (e.g., protein in
the case of DDGS). They can be used as valuable sources of protein, minerals, and other nutrients
depending on the source material and the chemical or physical processing, without causing any LF.
In the future, more grain will be used for food and fuel and more co-products could be available
for animal nutrition [
21
,
85
,
97
] or other purposes. Additional details about the nutritive value and
utilization of co-products from the biofuel industry in animal nutrition were recently compiled by the
FAO [95].
Co-products of agriculture and of the food/fuel industry can be used to replace concentrates and
forage from grassland. Based on plant yield level B (Table 5), we assumed for model calculations that
agricultural co-products (e.g., cereal straw) may replace 10%, 20%, or 30% of forage from grassland or
other sources in all diets, and co-products from the food or biofuel industry may replace 15%, 30%
or 45% of concentrate without any land use in the model calculations of all animal diets.
2.6. Animal Feeding
The roughage-to-concentrate ratio is of special importance in ruminant nutrition (Table 4).
Ruminants need a certain portion of forage (i.e., structural fiber) for overall health and to sustain normal
rumen fermentation processes [
98
]. The concentrate portion in ruminant diets increases with higher
animal yields (Table 4) because of higher energy and nutrient requirements of such animals and limited
feed intake capacity [
68
,
76
], but a certain level of forage is also required to keep animals healthy. Higher
ruminant yields require more concentrates and more arable land; however, the land requirements
can be decreased by the strategic and intensified use of co-products. Special attention must be paid
to feeding of potential human edible feeds to ruminants, such as cereal grains and pulses [
18
,
99
].
Typically, non-ruminants are fed with concentrates or co-products from the food or biofuel industries
(Table 4). Animals with lower yields or mature animals (e.g., pregnant, non-lactating sows) may
also consume certain amounts of forage in their diets. However, it is nearly impossible to include
forage in the diets of higher performing non-ruminant animals without drastically compromising
performance [39].
3. Results and Discussion
3.1. Animal Species and Protein Yields
Table 6shows the calculated results of yields from perennial crops, arable land (yield levels A, B,
and C; Table 5), and animals (Table 4) based on the animal species/categories, whereas Table 4shows
the forage-to-concentrate ratios. Co-products from the food and biofuel industry were not considered
as feeds in the calculations of Table 6. Animal species, animal yields, and plant yields were the most
important influencing factors on land use.
Lower plant yields (levels A and B) require more area per unit of edible protein, especially in the
case of perennial crops. Higher ruminant yields increase the arable land use because of the higher
energy density in the diets, but decrease the need for roughage/grassland. Beef cattle produce lower
protein amounts (Table 4) and need much more land per unit of edible protein than dairy cows (Table 6).
Only small amounts of forage were used for non-ruminants with lower yields. Higher animal
yields from non-ruminants result in a decreased need of arable land per kg of edible protein (Table 6).
Non-ruminants need a much greater area of arable land compared to that of ruminants because of the
higher concentrate portion in their diets (Table 4). More detailed calculations, which would have gone
Animals 2017,7, 25 11 of 19
beyond the scope of this study, are necessary to consider growing and reproductive periods for cows,
sows, and laying animals as well as animal losses.
In the following paragraph, our data is compared with selected references. De Vries and de Boer [
55
]
reviewed 16 LCA studies and found—in agreement with the present calculations (Table 6)—that
the production of 1 kg of beef or 1 kg of edible beef protein required the most land and had the
highest global warming potential followed by the production of 1 kg of pork, chicken, eggs, and milk.
There was a similar ranking on the basis of edible protein (beef > pork > chicken > milk > eggs; Table 7).
De Vries and de Boer [
55
] did not distinguish between grassland and arable land, however, this is
important to compare total land use with arable land use of ruminants and non-ruminants.
Table 7.
Land use per livestock product or protein (in m
2
/kg product and m
2
/kg protein; n= 16; [
55
]).
Food of Animal Origin Land Use (m2/kg Product) Land Use (m2/kg Protein)
Milk 1.1–2.0 33–59
Beef 127–491 144–258
Pork 8.9–12.1 47–64
Chicken meat 8.1–9.9 42–52
Eggs 4.5–6.2 35–48
1Suckler cows with calves.
Nguyen et al. [
100
] calculated the land use of beef produced in different systems and expressed
land use per kg of slaughter weight at the farm gate. One kilogram of slaughter weight is approximately
equal to about 100 g of edible protein (Tables 4and 6). The total land use varied, depending on the
production system, between 16.5 and 42.9 m
2
/year (between 0 and 36.9 m
2
of grassland and between
6.0 and 16.5 m
2
of cropland). The values per kg of edible protein varied between 165 and 430 m
2
and
are similar to values in Table 7. In agreement with data from Table 6, the largest area of arable land
(cereal grains, soybean) was needed for the highest weight gain, whereas more extensive feeding
systems resulted in lower weight gains, longer feeding periods, and more grassland use.
3.2. Grassland and Arable Land
Arable land is needed for food production, industrial raw materials, or the other F
´
s, like fuel,
fiber, flowers, and fun [
12
]. Therefore, animal nutrition will be forced to use human-inedible biomass
from grassland or co-products from the food and fuel industries to a much greater extent.
On a global scale, grassland could be an important potential source for ruminant nutrition.
Sustainable intensification of ruminant farming requires a development of grassland-based forage
production [
84
]. Sustainable grassland management includes avoiding overgrazing and a strategic use
of manure to maintain or improve productivity of the swards.
Nijdam et al. [
38
] analyzed numerous LCA and considered both total land use and the portion
which is grassland (Table 8). The calculated values for the land use (m
2
) per product and per kg of
protein show a large range and cover all the data shown in Tables 6,7and 9. Apart from the total
land use, the authors also determined that the grassland portion produced 1 kg of products or 1 kg of
protein by ruminants per m
2
. The results demonstrate that a better description of conditions used for
calculations (such as plant and animal yields, use of grassland and arable land, as well as co-products in
ruminant feeding and slaughtering and protein yields of assessed food of animal origin) are necessary
to allow for the comparison of the results of various studies and to draw more reliable conclusions.
Animals 2017,7, 25 12 of 19
Table 8. Land use (both total and grassland) per kg product and per kg edible protein [38].
Food of Animal Origin
(Number of Studies)
Total Land Use
(m2/kg Product)
Proportional Grassland Use
(m2/kg Product)
Total Land Use
(m2/kg Protein)
Milk (14) 1–2 1 26–54
Beef; allover (26)
Industrial systems (11)
Suckler herds (8)
Extensive pastoral systems (4)
7–420
15–29
33–158
286–420
2–420
2–26
25–140
250–420
37–2100
75–143
164–788
1430–2100
Mutton (5) 20–33 18–30 100–165
Pork (11) 8–15 Not applicable 40–75
Chicken meat (5) 5–8 Not applicable 23–40
Eggs (5) 4–7 Not applicable 29–52
Table 9.
Model calculations for the land use per kg edible protein depending on animal species/categories,
plant yields, animal performances, and co-products from the agriculture, food, and fuel industries
(see Tables 35for further details).
Protein Source Animal
Yield
Edible Protein Yield
(g/Day)
Grassland or Perennial Crops
(m2/kg Protein)
Arable Land or Cultivated Crops
(m2/kg Protein)
Plant Yield Level B 1
Replacement by Co-Products (%)
10 20 30 15 20 45
Cow milk 2 kg per d 67 108 96 84 0 0 0
5 kg per d 163 54 48 42 5 4 3
10 kg per d 323 32 28 24 7 6 5
20 kg per d 646 16 14 12 11 10 8
40 kg per d 1292 9 8 7 17 14 11
Goat milk 0.5 kg per d 17 54 48 42 0 0 0
1 kg per d 34 34 28 21 8 6 5
2 kg per d 68 20 18 14 10 8 6
Beef 200 g ADG 219 280 250 220 0 0 0
500 g ADG 48 115 105 90 13 10 8
1000 g ADG 95 54 48 42 19 15 12
1500 g ADG 143 36 32 28 26 21 16
Pork 200 g ADG 18 22 20 18 102 84 65
500 g ADG 45 7 6 5 55 46 36
700 g ADG 63 4 3 3 47 39 30
1000 g ADG 90 0 0 0 42 35 28
Chicken meat 20 g ADG 2.4 4 3 3 34 28 22
40 g ADG 4.8 2 2 1 21 18 14
60 g ADG 7.2 0 0 0 21 18 14
Eggs 20% LP 31.4 18 16 14 76 63 50
50% LP 3.4 5 5 4 42 35 28
70% LP 4.8 2 2 1 34 28 22
90% LP 6.2 0 0 0 34 28 22
1
Plant yields: Levels A (low), B (medium), and C (high); see Tables 3and 5;
2
Average daily gain;
3Laying performance.
3.3. Co-Products
As mentioned earlier, the feed sources may remarkably influence the calculation of the land use
per kg of product or edible protein. There has been a long discussion about the land area considered for
co-products when used in animal nutrition. Some authors consider a part of the area (20%–50%) used
for growing the main product (e.g., cereals, oilseeds) as an area for the co-product. However, in other
studies, land use was not considered for growing co-products at all [
21
,
58
,
101
,
102
]. In accordance with
this concept, co-products may replace forage and/or concentrates in the diets without any additional
LF as shown in Table 6in comparison to Table 9.
Calculations in Table 9show examples when up to 30% of grassland areas and up to 45% of arable
land areas are replaced by straw or other low quality roughages and by co-products from the food and
Animals 2017,7, 25 13 of 19
fuel industries, respectively. Such conditions should be considered if the land uses of various protein
sources are compared. Extensive examples for the accepted uses of co-products in farm animal diets
were recently summarized in the literature [
58
,
95
]. Ertl et al. [
58
] demonstrated that wheat bran and
sugar beet pulp as sole concentrates for dairy cows supported a daily milk production of more than
20 kg per cow under Austrian conditions.
The results of field studies (Tables 7and 8) and our model calculations (Tables 6and 9,
Tables 10 and 11)
clearly show that the study or calculation conditions should be carefully described
to allow appropriate understanding and interpretation of data.
Table 10.
Calculation to the net protein contribution of milk production to the human food chain under
consideration of various amounts of co-products in concentrate (on the basis of the data in Tables 2and 4).
Milk Yield Total
DM-Intake
Concentrate
Intake
Co-Products in
Concentrate
Human Edible
Protein Input
Human Edible
Protein Output
Proportion
Output to Input
(kg per d) (kg/d) (kg DM/d) (%) (g/d) (g/d) (g/g)
2 8 0 0 0 67 -
5 10 0.5 100 18 163 20
10 12 1.2 100 196 323 3.4
20 16 4.0 50 2262 646 2.4
40 25 12.5 25 31450 1292 0.9
1
50% concentrate wheat bran; 50% dried sugar beet pulp;
2
25% concentrate wheat bran; 25% dried sugar beet pulp;
30% concentrate as cereals; 10% soybean meal; 10% rapeseed meal;
3
12.5% concentrate wheat bran; 12.5% dried
sugar beet pulp; 50% concentrate as cereals; 15% soybean meal; 10% rapeseed meal (see Table 2; hef-fractions by [
57
]).
Table 11.
Calculation of the net protein contribution of food of animal origin to the human food chain
without co-products and under consideration of 50% of concentrate based on co-products (based on
data of Tables 2and 4).
Protein for
Human
Alimentation
Animal
Yield
DM
Intake
Concentrate
Intake 1
Co-Products in
Concentrate 2
Human Edible
Protein
Input 3Output 4
Proportion
Output to Input
(per d) (kg/d) (kg DM/d) (kg DM/d) (g/d) (g/d) (g/g)
Cow Milk 20 kg 16 4 0
2
493
262 646 1.3
2.4
Beef 1000 g
ADG 57 1.05 0
0.52
130
70 95 0.7
1.3
Pork 700 g
ADG 2 1.8 0
0.9
224
127 63 0.3
0.5
Chicken 60 g
ADG 0.08 0.08 0
0.04
10
67.2 0.7
1.2
Eggs 70% LP 60.11 0.1 0
0.05
12
74.8 0.4
0.7
1
80% cereals; 20% protein sources (soybeans, rapeseed);
2
50% co products; 30% cereals; 20% protein sources
(soybeans, rapeseed);
3
see Table 2; (hef-fractions by [
57
]);
4
see Table 4;
5
Average daily gain;
6
Laying performance.
3.4. Human Edible Protein
The human edible protein yield was calculated by dividing the protein output per edible animal
product by the edible protein intake and denoted protein score. Values >1 indicate a net yield in human
edible protein, whereas values <1 demonstrate a protein loss via animals. Table 10 shows the effects
of milk yield and required concentrate amounts on the human edible protein input and the output
per cow as well as the protein score (as defined above; [
57
,
58
]). The higher the milk yield and the
higher the protein intake from edible concentrate, the lower the protein score. In agreement with the
calculated data (Table 10), Ertl et al. [
58
] calculated protein scores between 1.40 and 1.87 for milk for
the potentially human-edible plant protein for 30 Austrian dairy farms with average daily milk yields
between 20 and 25 kg.
Animals 2017,7, 25 14 of 19
Table 11 evaluates protein sources for the production of food of animal origin. In the first case, no
co-products are used in the diets; in the second case, 50% of concentrate are consumed as co-products,
mainly wheat bran, and sugar beet pulp. The data show that in addition to the lower need of arable
land (see Table 9), the protein score for all protein sources is higher if co-products are used in animal
feeding. Except milk, the protein scores for all food of animal origin are <1 without co-products as part
of concentrate (Table 11).
4. Conclusions
Arable land use per unit product or protein of animal origin depends mainly on animal species
and categories, animal production system, plant and animal yields, use of grassland, and the portion
of co-products in animal rations. The results presented here show that a clear and precise description
of study conditions and/or the basis of calculations is an inevitable prerequisite to allow for a fair
comparison of results concerning land use. More complex calculations, considering characteristics of
efficient use of limited resources and the reduction of emissions, seem to be helpful to find and specify
optima in the production of food of animal origin. Pertinent references are mentioned for further details.
The following aspects and measurements should be considered in future calculations [103]:
Use of arable land (i.e., competition between various users [2,12])
Comparison of output of human edible protein with input via feeding (should be >1 [57,58])
Efficient use of water for feed and animal production [9,75]
Minimization of the use of fuel and other limited natural resources in the food chain [13,14]
Utilization of permanent grassland and co-products from agriculture and industry [21,60]
Reduction of greenhouse gas emissions per product or per kg of edible protein and along the
whole food chain [4145]
Plant and animal breeding as the starting points of the human food chain [48,78]
Evaluating the potential of edible insects as protein sources for food and feed [49,104]
Calculation of land use per inhabitant considering eating patterns of the population [17,35]
Reduction of food wastage (presently equal to about 1.4 billion ha land or 30% of the world’s
agricultural area [105,106]
The production of food of animal origin is a very complex process, and selective
considerations, i.e., focusing on single factors, do not provide an assessment that reflects the complexity
of the subject. Cooperation of animal scientists (e.g., nutritionists, geneticists, animal keepers/farmers,
veterinarians, etc.) with scientists working along the food chain in the fields of plant and feed science,
ecology, and economy contributes to improved problem solving and to developing improved and
resilient LF. In summary, the production of more food for more people with fewer resources and
emissions is one of the most important challenges for all of those involved in feed and food science
and production.
Author Contributions:
The idea for the manuscript was developed by Gerhard Flachowsky. He was the principal
organizer of the work and drafted the manuscript. Ulrich Meyer and Karl-Heinz Südekum contributed to
the paper.
Conflicts of Interest: The authors declare no conflict of interest.
References
1.
Food and Agriculture Organization of the United Nations (FAO); International Fund for Agricultural
Development (IFAD); World Food Programme (WFP). The State of Food Insecurity in the World 2015. Meeting
the 2015 International Hunger Targets: Taking Stock of Uneven Progress; FAO: Rome, Italy, 2015.
2.
Fedoroff, N.V.; Battisti, D.S.; Beachy, R.N.; Cooper, P.J.; Fischhoff, D.A.; Hodges, C.N.; Knauf, V.C.; Lobell, D.;
Mazur, B.J.; Molden, D.; et al. Radically rethinking agriculture for the 21st century. Science
2010
,327, 833–834.
[CrossRef] [PubMed]
Animals 2017,7, 25 15 of 19
3.
Godfray, H.C.; Beddington, J.R.; Crute, I.R.; Haddad, L.; Lawrence, D.; Muir, J.F.; Pretty, J.; Robinson, S.;
Thomas, S.M.; Toulmin, C. Food security: The challenge of feeding 9 billion people. Science
2010
,327, 812–818.
[CrossRef] [PubMed]
4.
Foley, J.A.; Ramankutty, N.; Brauman, K.A.; Cassidy, E.S.; Gerber, J.S.; Johnston, M.; Mueller, N.D.;
O’Connell, C.; Ray, D.K.; West, P.C.; et al. Solutions for a cultivated planet. Nature
2011
,478, 337–342.
[CrossRef] [PubMed]
5.
Aiking, H. Protein production: Planet, profit, plus people? Am. J. Clin. Nutr.
2014
,100, 483s–489s. [CrossRef]
[PubMed]
6.
Beddington, J.R.; Asaduzzaman, M.; Clark, M.; Fernández, A.; Guillou, M.; Jahn, M.; Erda, L.; Mamo, T.;
van Bo, N.; Nobre, C.A.; et al. Achieving Food Security in the Face of Climate Change: Final Report from the
Commission on Sustainable Agriculture and Climate Change; CGIAR Research Program on Climate Change,
Agriculture and Food Security (CCAFS): Copenhagen, Denmark, 2012.
7.
Schlink, A.C.; Nguyen, M.L.; Viljoen, G.J. Water requirements for livestock production: A global perspective.
Rev. Sci. Tech. 2010,29, 603–619. [CrossRef] [PubMed]
8.
Deikman, J.; Petracek, M.; Heard, J.E. Drought tolerance through biotechnology: Improving translation from
the laboratory to farmers’ fields. Curr. Opin. Biotechnol. 2012,23, 243–250. [CrossRef] [PubMed]
9.
Hoekstra, A.Y.; Chapagain, A.K.; Zhang, G.P. Water footprints and sustainable water allocation. Sustainability
2016,8, 20. [CrossRef]
10.
Hall, D.C.; Hall, J.V. Concepts and measures of natural-resource scarcity with a summary of recent trends.
J. Environ. Econ. Manag. 1984,11, 363–379. [CrossRef]
11.
Scholz, R.W.; Wellmer, F.W. Approaching a dynamic view on the availability of mineral resources: What we
may learn from the case of phosphorus? Glob. Environ. Chang. 2013,23, 11–27. [CrossRef]
12.
Aerts, S. Agriculture’s 6 F’s and the need for more intensive agriculture. In Climate Change and Sustainable
Development; Potthast, T., Meisch, S., Eds.; Wageningen Academic Publisher: Wageningen, The Netherlands,
2012; pp. 192–195.
13.
Boonen, R.; Aerts, S.; de Tavernier, L. Which sustainability suits you? In Climate Change and Sustainable
Development; Potthast, T., Meisch, S., Eds.; Wageningen Academic Publisher: Wageningen, The Netherlands,
2012; pp. 43–48.
14.
Food and Agriculture Organization of the United Nations (FAO). How to Feed the World in 2050; FAO: Rome,
Italy, 2009.
15.
Food and Agriculture Organization of the United Nations (FAO). The State of Food and Agriculture. Livestock
in the Balance. State of Foods and Agriculture; FAO: Rome, Italy, 2009.
16.
Alexandratos, N.; Bruinsma, J. World Agriculture towards 2030/2050: The 2012 Revision; FAO: Rome, Italy, 2012.
17.
Kastner, T.; Rivas, M.J.; Koch, W.; Nonhebel, S. Global changes in diets and the consequences for land
requirements for food. Proc. Natl. Acad. Sci. USA 2012,109, 6868–6872. [CrossRef] [PubMed]
18.
Cassidy, E.S.; West, P.C.; Gerber, J.S.; Foley, J.A. Redefining agricultural yields: From tonnes to people
nourished per hectare. Environ. Res. Lett. 2013,8, 034015. [CrossRef]
19.
Kebreab, E. Sustainable Animal Agriculture; CAB International: Wallingford, UK; Cambridge, MA, USA, 2013.
20. Smil, V. Feeding the World: A Challenge for the Twenty-First Century; The MIT Press: Cambridge, MA, USA, 2001.
21.
Ertl, P.; Zebeli, Q.; Zollitsch, W.; Knaus, W. Feeding of by-products completely replaced cereals and pulses in
dairy cows and enhanced edible feed conversion ratio. J. Dairy Sci.
2015
,98, 1225–1233. [CrossRef] [PubMed]
22.
World Health Organization (WHO); Food and Agriculture Organization of the United Nations (FAO);
United Nations University (UNU). Protein and Amino Acid Requirements in Human Nutrition; World Health
Organization: Geneva, Switzerland, 2002.
23.
D’Mello, J.P.F. Amino Acids in Human Nutrition and Health; CAB International: Wallingford, UK; Cambridge,
MA, USA, 2012; p. 584.
24.
FAO (Food and Agriculture Organization of the United Nations). Greenhouse Gas Emissions from the Dairy Sector;
FAO Animal Production and Health Division: Rome, Italy, 2010.
25.
Wennemer, H.; Flachowsky, G.; Hoffmann, V. Protein, Population, Politics—How Protein Can Be Supplied
Sustainable in the 21st Century; Plexus Verlag: Mittenberg, Switzerland; Frankfurt/Main, German, 2006; p. 160.
26.
Reynolds, L.P.; Wulster-Radcliffe, M.C.; Aaron, D.K.; Davis, T.A. Importance of animals in agricultural
sustainability and food security. J. Nutr. 2015,145, 1377–1379. [CrossRef] [PubMed]
27. Waterlow, J.C. The mysteries of nitrogen balance. Nutr. Res. Rev. 1999,12, 25–54. [CrossRef] [PubMed]
Animals 2017,7, 25 16 of 19
28.
Jackson, A.A.; Truswell, S. Protein. In Essentials of Human Nutrition, 3rd ed.; Mann, J., Truswell, S., Eds.;
Oxford Univ. Press: Oxford, UK, 2007; pp. 53–72.
29.
Rand, W.M.; Pellett, P.L.; Young, V.R. Meta-analysis of nitrogen balance studies for estimating protein
requirements in healthy adults. Am. J. Clin. Nutr. 2003,77, 109–127. [PubMed]
30.
DGE (Deutsche Gesellschaft für Ernährung); ÖGE (Österreichische Gesellschaft für Ernährung);
SGE (Schweizerische Vereinigung für Ernährung). Referenzwerte für die Nährstoffzufuhr; Umschau/Braus Verlag:
Frankfurt am Main, Germany, 2000.
31.
Avadi, A.; Freon, P. Life cycle assessment of fisheries: A review for fisheries scientists and managers. Fish. Res.
2013,143, 21–38. [CrossRef]
32.
Keyzer, M.A.; Merbis, M.D.; Pavel, I.F.P.W.; van Wesenbeeck, C.F.A. Diet shifts towards meat and the effects
on cereal use: Can we feed the animals in 2030? Ecol. Econ. 2005,55, 187–202. [CrossRef]
33.
Guyomard, H.; Manceron, S.; Peyraud, J.L. Trade in feed grains, animals, and animal products: Current
trends, future prospects, and main issues. Anim. Front. 2013,3, 14–18. [CrossRef]
34.
Wu, G.; Fanzo, J.; Miller, D.D.; Pingali, P.; Post, M.; Steiner, J.L.; Thalacker-Mercer, A.E. Production and
supply of high-quality food protein for human consumption: Sustainability, challenges, and innovations.
Ann. N. Y. Acad. Sci. 2014,1321, 1–19. [CrossRef] [PubMed]
35.
Guyomard, H.; Darcy-Vrillon, B.; Esnouf, C.; Marin, M.; Russel, M.; Guillou, M. Eating patterns and food
systems: Critical knowledge requirements for policy design and implementation. Agric. Food Secur. 2012,1, 13.
[CrossRef]
36.
Pimentel, D.; Pimentel, M. Sustainability of meat-based and plant-based diets and the environment. Am. J.
Clin. Nutr. 2003,78, 660S–663S. [PubMed]
37.
Baroni, L.; Cenci, L.; Tettamanti, M.; Berati, M. Evaluating the environmental impact of various dietary
patterns combined with different food production systems. Eur. J. Clin. Nutr.
2007
,61, 279–286. [CrossRef]
[PubMed]
38.
Nijdam, D.; Rood, T.; Westhoek, H. The price of protein: Review of land use and carbon footprints from life
cycle assessments of animal food products and their substitutes. Food Policy 2012,37, 760–770. [CrossRef]
39.
Peters, C.J.; Wilkins, J.L.; Fick, G.W. Testing a complete-diet model for estimating the land resource
requirements of food consumption and agricultural carrying capacity: The new york state example.
Renew. Agric. Food Syst. 2007,22, 145–153. [CrossRef]
40.
Westhoek, H.; Lesschen, J.P.; Rood, T.; Wagner, S.; de Marco, A.; Murphy-Bokern, D.; Leip, A.;
van Grinsven, H.; Sutton, M.A.; Oenema, O. Food choices, health and environment: Effects of cutting
Europe’s meat and dairy intake. Glob. Environ. Chang. 2014,26, 196–205. [CrossRef]
41.
Intergovernmental Panel on Climate Change (IPCC). Guidelines for National Greenhouse Gas Inventories;
Agriculture, Forestry and Other Land Use; Prepared by the National Greenhouse Gas Inventories Programme;
Institute for Global Environmental Strategies (IGES): Hayama, Japan, 2006.
42.
Williams, A.G.; Audsley, E.; Sanders, D.L. Determining the Environmental Burdens and Resource Use in the
Production of Agricultural and Horticultural Commodities; Defra (Department for Environment, Food and
Eural Affairs) project report IS0205; Natural Resource Manaement Institute, Cranfield University:
Bedford, UK, 2006.
43.
Hristov, A.N.; Oh, J.; Lee, C.; Meinen, R.; Montes, F.; Ott, T.; Firkins, J.; Rotz, A.; Dell, C.; Adesogan, A.T.; et al.
Mitigation of Greenhouse Gas Emissions in Livestock Production—A Review of Technical Options for Non-CO
2
Emissions; FAO: Rome, Italy, 2013.
44.
Flachowsky, G. Carbon footprints for food of animal origin. In Livestock Production and Climate Change;
Malik, P.K., Malik, P.K., Bhatta, R., Takahashi, J., Kohn, R.A., Prasad, C.S., Eds.; CAB International:
Wallingford, UK; Cambridge, MA, USA, 2015; pp. 125–145.
45.
Gerber, P.J.; Steinfeld, H.; Henderson, B.; Mollet, A.; Opio, C.; Dijkman, F.; Falcucci, A.; Tempio, G.
Tackling Climate Change through Livestock—A Global Assessment of Emissions and Mitigation Opportunities;
Food and Agriculture Organisation of the United Nations (FAO)/CAB International: Rome, Italy;
Wallingford, UK, 2013.
46.
Friel, S.; Dangour, A.D.; Garnett, T.; Lock, K.; Chalabi, Z.; Roberts, I.; Butler, A.; Butler, C.D.; Waage, J.;
McMichael, A.J.; et al. Public health benefits of strategies to reduce greenhouse-gas emissions: Food and
agriculture. Lancet 2009,374, 2016–2025. [CrossRef]
Animals 2017,7, 25 17 of 19
47.
Wheeler, T.; Reynolds, C. Predicting the risks from climate change to forage and crop production for animal feed.
Anim. Front. 2013,3, 36–41. [CrossRef]
48.
Niemann, H.; Kuhla, B.; Flachowsky, G. Perspectives for feed-efficient animal production. J. Anim. Sci.
2011
,
89, 4344–4363. [CrossRef] [PubMed]
49.
Makkar, H.P.S.; Tran, G.; Heuze, V.; Ankers, P. State-of-the-art on use of insects as animal feed. Anim. Feed
Sci. Technol. 2014,197, 1–33. [CrossRef]
50.
Makkar, H.P.S.; Ankers, P. Towards sustainable animal diets: A survey-based study. Anim. Feed Sci. Technol.
2014,198, 309–322. [CrossRef]
51.
Bruinsma, J. The resource outlook to 2050: By how much do land, water and crop yields need to increase
by 2050? In Expert Meeting on How to Feed the World in 2050; Food and Agriculture Organization of the United
Nations/Economic and Social Development Department: Rome, Italy, 2009.
52.
Food and Agriculture Organization of the United Nations (FAO). Dietary Protein Quality Evaluation in
Human Nutrition; FAO: Rome, Italy, 2013.
53.
Bessou, C.; Ferchaud, F.; Gabrielle, B.; Mary, B. Biofuels, greenhouse gases and climate change. A review.
Agron. Sustain. Dev. 2011,31, 1–79. [CrossRef]
54.
Elferink, E.V.; Nonhebel, S. Variations in land requirements for meat production. J. Clean. Prod.
2007
,15,
1778–1786. [CrossRef]
55.
De Vries, M.; de Boer, I.J.M. Comparing environmental impacts for livestock products: A review of life cycle
assessments. Livest. Sci. 2010,128, 1–11. [CrossRef]
56.
Zollitsch, W.; Hörtenhuber, S.; Piringer, G. Life cycle assessment—Aussagekraft und grenzen im kontext
tierischer produktionssysteme. Verband Deutscher Landwirtschaftlicher Untersuchungs- und Forschungsanstalten
2012,68, 57–70.
57.
Wilkinson, J.M. Re-defining efficiency of feed use by livestock. Animal
2011
,5, 1014–1022. [CrossRef]
[PubMed]
58.
Ertl, P.; Klocker, H.; Hortenhuber, S.; Knaus, W.; Zollitsch, W. The net contribution of dairy production to
human food supply: The case of austrian dairy farms. Agric. Syst. 2015,137, 119–125. [CrossRef]
59.
Van Zanten, H.H.E.; Mollenhorst, H.; Klootwijk, C.W.; van Middelaar, C.E.; de Boer, I.J.M. Global food
supply: Land use efficiency of livestock systems. Int. J. Life Cycle Assess. 2016,21, 747–758. [CrossRef]
60. Jeroch, H.; Flachowsky, G.; Weissbach, F. Futtermittelkunde; Elsevier: München, Germany, 1993.
61.
Food and Agriculture Organization of the United Nations (FAO); World Health Organization (WHO).
Protein Quality Evaluation: Report of the Joint Fao/Who Expert Consultation, Bethesda, MD, USA, 4–8 December 1989;
FAO/WHO: Rome, Italy, 1991.
62.
Flachowsky, G.; Kamphues, J. Carbon footprints for food of animal origin: What are the most preferable
criteria to measure animal yields? Animals 2012,2, 108–126. [CrossRef] [PubMed]
63.
Peters, G.M.; Rowley, H.V.; Wiedemann, S.; Tucker, R.; Short, M.D.; Schulz, M. Red meat production in
australia: Life cycle assessment and comparison with overseas studies. Environ. Sci. Technol.
2010
,44,
1327–1332. [CrossRef] [PubMed]
64.
Doreau, M.; van der Werf, H.M.G.; Micol, D.; Dubroeucq, H.; Agabriel, J.; Rochette, Y.; Martin, C.
Enteric methane production and greenhouse gases balance of diets differing in concentrate in the fattening
phase of a beef production system. J. Anim. Sci. 2011,89, 2518–2528. [CrossRef] [PubMed]
65.
Flachowsky, G. Efficiency of energy and nutrient use in the production of edible protein of animal origin.
J. Appl. Anim. Res. 2002,22, 1–24. [CrossRef]
66.
GfE (Gesellschaft für Ernährungsphysiologie). Recommendations for Energy and Nutrient Requirements of Beef Cattle;
DLG-Verlag: Frankfurt, Germany, 1995. (In German)
67.
GfE (Gesellschaft für Ernährungsphysiologie). Recommendations for Energy and Nutrient Requirements of Laying
Hens and Broilers; DLG-Verlag: Frankfurt, Germany, 1999. (In German)
68.
GfE (Gesellschaft für Ernährungsphysiologie). Recommendations for Energy and Nutrient Requirements of dairy
Cattle and Heifers; DLG-Verlag: Frankfurt, Germany, 2001. (In German)
69.
GfE (Gesellschaft für Ernährungsphysiologie). Recommendations for the Supply of Energy and Nutrients to Pigs;
DLG-Verlag: Frankfurt, Germany, 2008.
70.
Souci, S.W.; Fachmann, W.; Kraut, H. Food Composition and Nutrition Tables: Die Zusammensetzung
der Lebensmittel, Nährwert-Tabellen la Composition des Aliments Tableaux des Valeurs Nutritives, 8th ed.;
Wissenschaftliche Verlagsgesellschaft: Stuttgart, Germany, 2016.
Animals 2017,7, 25 18 of 19
71.
Mekonnen, M.M.; Hoekstra, A.V. The Green, Blue and Grey Water Footprint of Farm Animals and Animal Products;
UNESCO-IHE: Delft, The Netherlands, 2010.
72.
Andersen, G. Food Table for the Practice: The Little Souci-Fachmann-Kraut; Wissenschaftliche Verlagsgesellschaft mbH:
Stuttgart, Germany, 2011. (In German)
73.
Lesschen, J.P.; van den Berg, M.; Westhoek, H.J.; Witzke, H.P.; Oenema, O. Greenhouse gas emission profiles
of european livestock sectors. Anim. Feed Sci. Technol. 2011,166–167, 16–28. [CrossRef]
74.
USDA (United States Department of Agriculture) Agricultural Research Service; National Nutrient Database
for Standard Reference. Available online: https://ndb.nal.usda.gov/ndb/ (acessed on 13 December 2016).
75.
Mekonnen, M.M.; Hoekstra, A.Y. A global assessment of the water footprint of farm animal products.
Ecosystems 2012,15, 401–415. [CrossRef]
76.
NRC (National Research Counsil). Nutrient Requirements of Dairy Cattle: Seventh Revised Edition, 2001;
The National Academies Press: Washington, DC, USA, 2001; p. 408.
77.
GfE (Gesellschaft für Ernährungsphysiologie). Recommendations for the Supply of Energy and Nutrients to
Horses; DLG-Verlag: Frankfurt, Germany, 2014. (In German)
78. Flachowsky, G. Animal Nutrition with Transgenic Plants; CABI: Wallingford, UK, 2013.
79. Van Soest, P.J. Nutritional Ecology of the Ruminant; Cornell University Press: Ithaca, NY, USA, 1994.
80.
Becker, M.; Nehring, K. Handbook of Feeds. Handbuch der Futtermittel; Hamburg: Berlin, Germany, 1969;
Volumes 1–3.
81.
Beyer, M.; Jentsch, W.; Chudy, A. Rostock Feed Evaluation System: Reference Numbers of Feed Value and
Requirement on the Base of Net Energy; Plexus-Verlag: Miltenberg-Frankfurt, Germany, 2003.
82.
Wheeler, J.L. Pastures and pasture research in Southern Australia. In Temperate Pastures: Their Production, Use
and Management; Wheeler, J.L., Pearson, C.J., Roberts, G.E., Eds.; CRISO Publishing: Melbourne, Australia, 1987.
83.
Gill, M. Converting Feed into Human Food: The Multiple Dimensions of Efficiency; In Optimization of Feed Use
Efficiency in Ruminant Production Systems. Proceedings of the FAO Symposium, 27 November 2012, Bangkok,
Thailand; FAO Animal Production and Health Proceedings, No. 16.; Makkar, H.P.S., Beever, D., Eds.;
FAO (Food and AgricultureOrganization of the United Nations): Rome, Italy, 2013; pp. 1–13.
84.
Taube, F.; Gierus, M.; Hermann, A.; Loges, R.; Schönbach, P. Grassland and globalization-challenges for
north-west European grass and forage research. Grass Forage Sci. 2014,69, 2–16. [CrossRef]
85.
Ertl, P.; Zebeli, Q.; Zollitsch, W.; Knaus, W. Feeding of wheat bran and sugar beet pulp as sole supplements
in high-forage diets emphasizes the potential of dairy cattle for human food supply. J. Dairy Sci.
2016
,99,
1228–1236. [CrossRef] [PubMed]
86.
Kratli, S.; Huelsebusch, C.; Brooks, S.; Kaufmann, B. Pastoralism: A critical asset for food security under
global climate change. Anim. Front. 2013,3, 42–50. [CrossRef]
87.
Powell, J.M.; MacLeod, M.; Vellinga, T.V.; Opio, C.; Falcucci, A.; Tempio, G.; Steinfeld, H.; Gerber, P.
Feed-milk-manure nitrogen relationships in global dairy production systems. Livest. Sci.
2013
,152, 261–272.
[CrossRef]
88.
Gill, M.; Smith, P.; Wilkinson, J.M. Mitigating climate change: The role of domestic livestock. Animal
2010
,4,
323–333. [CrossRef] [PubMed]
89.
Opio, C.; Gerber, P.; Mottet, A.; Falcucci, A.; Tempio, G.; MacLeod, M.; Vellinga, T.; Henderson, B.; Steinfeld, H.
Greenhouse Gas Emissions from Ruminant Supply Chains—A Global Life Cycle Assessment; Food and Agriculture
Organization of the United Nations (FAO): Rome, Italy, 2013.
90.
Soussana, J.F.; Loiseau, P.; Vuichard, N.; Ceschia, E.; Balesdent, J.; Chevallier, T.; Arrouays, D. Carbon cycling
and sequestration opportunities in temperate grasslands. Soil Use Manag. 2004,20, 219–230. [CrossRef]
91.
Soussana, J.F.; Tallec, T.; Blanfort, V. Mitigating the greenhouse gas balance of ruminant production systems
through carbon sequestration in grasslands. Animal 2010,4, 334–350. [CrossRef] [PubMed]
92.
Sundstol, F.; Owen, E. Straw and Other Fibrous by Products as Feed; Elsevier: Amsterdam, The Netherlands,
1984; Volume 14.
93.
Flachowsky, G. Stroh als Futtermittel: Ergebnisse und Erfahrungen Bei der Strohaufbereitung und Beim Einsatz von
Unterschiedlich Behandeltem Stroh als Futtermittel; VEB Deutscher Landwirtschaftsverlag: Berlin, Germany, 1987.
94.
Kling, M.; Wöhlbier, W. Trade Feestuffs (in German: Handelsfuttermittel); Verlag Eugen Ulmer: Stuttgart,
Germany, 1983.
95.
Food and Agriculture Organization of the United Nations (FAO). Biofuel Co-Products as Livestock
Feed—Opportunities and Challenges; FAO: Rome, Italy, 2012.
Animals 2017,7, 25 19 of 19
96.
Gerber, P.; Vellinga, T.; Opio, C.; Steinfeld, H. Productivity gains and greenhouse gas emissions intensity in
dairy systems. Livest. Sci. 2011,139, 100–108. [CrossRef]
97.
Windisch, W.; Fahn, C.; Brugger, D.; Deml, M.; Buffler, M. Strategies for sustainable animal nutrition.
Züchtungskunde 2013,85, 40–53.
98.
Reynolds, C.K.; Crompton, L.A.; Mills, J.A.N. Improving the efficiency of energy utilisation in cattle.
Anim. Prod. Sci. 2011,51, 6–12. [CrossRef]
99.
Bradford, G.E. Contributions of animal agriculture to meeting global human food demand. Livest. Prod. Sci.
1999,59, 95–112. [CrossRef]
100.
Nguyen, T.L.T.; Hermansen, J.E.; Mogensen, L. Environmental consequences of different beef production
systems in the eu. J. Clean. Prod. 2010,18, 756–766. [CrossRef]
101.
Bockisch, F.-J.; Röver, M. Bewertung von Verfahren der Ökologischen und Konventionellen Landwirtschaftlichen
Produktion im Hinblick auf den Energieeinsatz und Bestimmte Schadgasemissionen: Studie als Sondergutachten im
Auftrag des Bundesministeriums für Ernährung, Landwirtschaft und Forsten; Landbauforschung Völkenrode,
Sonderheft 211: Braunschweig, Germany, 2000.
102.
Ertl, P.; Knaus, W.; Zollitsch, W. An approach to including protein quality when assessing the net contribution
of livestock to human food supply. Animal 2016,10, 1883–1889. [CrossRef] [PubMed]
103.
NRC (National Research Council of the National Academies). Critical Role of Animal Science Research in Food
Security and Sustainability; National Academic Press: Washington, DC, USA, 2015; p. 415.
104.
EFSA (European Food Safety Authority). Risk profile related to production and consumption of insects as
food and feed. EFSA J.
2015
,13, 4257. Available online: http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.
2015.4257/epdf (acessed on 13 December 2016).
105.
Food and Agriculture Organization of the United Nations (FAO). Food Wastage Footprint—Impacts on Natural
Resources; FAO: Rome, Italy, 2013.
106.
Blanke, M. Challenges of reducing fresh produce waste in Europe—From farm to fork. Agriculture
2015
,5, 389.
[CrossRef]
©
2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
... Hence, future feeding concepts should aim to reduce food competition by feeding cattle with roughage-rich rations according to their physiological advantages as ruminants. (Flachowsky et al., 2017;Windisch & Flachowsky, 2020) ...
... Increasing the proportion of roughage in cattle feed reduces the required amount of high-quality feedstuffs and thus reduces the competition for livestock feed and food for humans. (Flachowsky et al., 2017;Windisch & Flachowsky, 2020) Increasing the amount of roughage in cattle nutrition contributes to rumen health and thus promotes animal welfare (Suárez et al., 2007;Chibisa et al., 2020). However, roughagerich rations provide lower amounts of energy and nutrients. ...
Thesis
This doctoral thesis generates basic data to determine the nutrient and energy requirements of growing Fleckvieh (German Simmental) beef bulls under different feeding regimes. Hence, analyses of body composition and nutrient and energy accretion rates were performed in growing Fleckvieh bulls fed rations with different energy concentrations. The results illustrate allometric growth patterns in cattle and demonstrate how more sustainable feeding concepts can be realized. Seventy-two Fleckvieh bull calves, representing the current genetic level, were customarily reared. During the fattening period, the calves were allocated to normal energy and high-energy treatment groups fed 11.6 and 12.4 megajoule metabolizable energy per kilogram dry matter, respectively. Differences in dietary energy concentrations were achieved by varying the amounts of concentrates and maize silage in the feeding rations. Bulls from both feeding groups were slaughtered in a serial slaughter trial at final live weights of 120, 200, 400, 600, and 780 kilograms. During slaughter and subsequent beef cutting, the bulls’ bodies were dissected into individual tissue fractions, which were homogenized and analyzed for their chemical composition. Regression modeling was applied to determine the body composition of the growing bulls. The first derivative of the individual equations was used to calculate the gain composition and describe changes in body proportions throughout the growth process. The study results are presented in two publications. The first publication specifies fattening and slaughter performance in current Fleckvieh bulls at defined final weights and under feeding regimes with varying energy concentrations. The results demonstrate that Fleckvieh bulls at the current genetic level feature increased growth potential and final weights, compared to Fleckvieh bulls in previous decades. Current Fleckvieh bulls efficiently exploited energy and nutrients in the offered feed and exhibited increased daily weight gains, leading to high final weights. High-energy fed bulls showed increased growth performance compared to bulls fed a regular-energy diet. Differences in carcass composition and meat quality traits in growing bulls from both treatment groups were not recorded. Consequently, Fleckvieh bulls fed rations with lower energy concentrations needed more time to reach the highest target weight. However, slaughter performance and meat quality traits were comparable to those of bulls fed high-energy diets. The second publication assesses body tissue composition, body chemical composition, and the composition of body weight gain in growing Fleckvieh bulls fed rations with varying energy concentrations. The results indicate that feed containing varying amounts of energy did not alter body composition or energy and nutrient accretion rates in growing Fleckvieh beef bulls. During growth, unequal changes in body tissue gain and nutrient accretion, attributable to allometric cattle growth, became apparent. Comparison with earlier research reveals that current Fleckvieh bulls with high live weights feature lower rates of crude protein accretion but higher crude fat and energy accumulation rates than bulls in previous decades. Hence, feeding recommendations for growing Fleckvieh bulls must be regularly adjusted to suit energy and nutrient requirements and increase daily weight gain and target weights. In summary, growing Fleckvieh bulls in the normal and high-energy feed intake groups demonstrated similar body composition, carcass composition, composition of gain, and meat quality traits. It can be concluded that feeding high-energy rations is not necessary from a metabolic standpoint. Fleckvieh bulls can be fattened using lower energy, roughage-rich rations according to their physiological advantages as ruminants, which also contributes to animal welfare. Future feeding concepts should aim to increase roughage feeding in cattle nutrition to reduce competition for resources used in livestock feed and human food production. Furthermore, phase feeding should be used to feed growing cattle according to their energy and nutrient requirements and reduce nitrogen excretion and the resulting environmental impacts. Hence, more sustainable cattle feeding concepts can contribute to resource conservation, environmental protection, and increased animal welfare.
... Population growth has increased demand for food, especially protein sources of animal origin (Flachowsky et al., 2017). This increased meat production can be obtained by the use of animal diets that provide higher carcass yield, different supplements, and animal feed additives, among others. ...
Article
Background Microbiological control with the development of robust methodologies has been extensively studied in food science. However, equally important as reducing the microbial load is understanding the sources that led that food to be contaminated. In this sense, we approach in the present review two distinct events: (1) Super-shedding (SS), characterized by the high concentration of a pathogen in the animal's faeces (above 104 CFU/g); and (2) High Event Period (HEP) characterized by unexpectedly high contamination in a batch of meat at an abattoir, which may be localized or systemic. Scope and approach The aim of the present review is to explain the aspects involved in these events, bringing insights into the possible cause, and how they impact food production (with emphasis on beef and milk processing), and alternative strategies for microbial detection and inactivation. Key findings and conclusions A microbial biofilm at the recto-anal junction of cattle is a likely cause of the SS event. In addition, the potential for biofilm formation seems to be a converging point between SS and HEP events, and results obtained by whole genome sequencing have demonstrated that a SS strain had the potential to form biofilm and genetic proximity to another strain involved in a food outbreak. Finally, investigation of the impacts of SS and HEP inside a production unit can define the critical control points that will have a direct impact on the reduction of contamination inside an abattoir or dairy.
... Nonetheless, the sustainable intensification of their systems implies an increasing reliance on concentrates (or energy/protein supplements), mainly during the rearing and finishing phases (Cardoso et al., 2020;Hoffmann et al., 2021a). In the context of sustainable production, the search for high animal performance and at the same time, reduction of human-edible inputs, such as cereal grains, which are largely included in animal and human nutrition, indicates that the use of by-products can be promising, especially in terms of energy supply (Flachowsky et al., 2017). Therefore, reducing the amount of human-edible feedstuff in cattle diets is a key factor for sustainable livestock systems (Ertl et al., 2016b). ...
Article
Sustainable intensification of tropical grasslands has been identified by researchers and stakeholders as a solution to decrease greenhouse gas emissions and deforestation. However, there are concerns about food security and the role of livestock in feed-food competition between animals and humans involving land and other resources. We aimed to determine the net protein contribution (NPC), a feed-food competitiveness index, of tropical beef cattle raised on extensive systems or finished in pastures or conventional feedlots, under different levels of intensification. We modelled five scenarios, from cow-calf to slaughter, based on common beef cattle practices in Brazil, whose main production system is grazing. Scenario 1 represented the lowest level of intensification and the most extensive system. Scenario 2 represented a moderately extensive system. Scenarios 3, 4, and 5 represented different degrees and practices of intensification, with animals in cow-calf and stocker phases raised solely on well-managed permanent pastures. In Scenario 3, the animals were finished in a feedlot. In Scenarios 4 and 5, all animals in the stocker phase received a protein-energy supplement, but in Scenario 4, animals were finished in a permanent pasture with high-concentrate intake. In Scenario 5, animals were finished in a feedlot. The human-edible protein (heP) conversion efficiency (hePCE) was calculated as the ratio of heP produced (meat) to heP consumed as feed, and the NPC was the product of hePCE using the protein quality ratio, accounting for the digestible indispensable amino acid score content. An hePCE > 1 indicated that meat production did not compete with humans for food, and an NPC > 1 indicated that it contributed positively to meet human requirements. Meat production and heP intake consistently increased with intensification. The greatest hePCE values were from Scenarios 1 (9.2), 2 (2.2), and 3 (1.2), which were essentially pasture-fed systems, compared to Scenarios 4 and 5 (average of 1.0). The NPC varied from 24.1 (Scenario 1) to 2.6 (Scenario 5). The area required to produce 1 kg of carcass decreased from 147 to 45 m², and the slaughter age decreased from 36 to 21 months from the most extensive to intensive systems. Brazilian beef cattle production contributes positively to the protein requirements of humans without limiting human food supplies. The intensification of tropical grazing beef systems is a key strategy to save land and produce more meat without limiting food for humans, playing an important role in the food security agenda.
... Farm animals, dairy products, fishing, and the textile industry are just a few of the industries that generate waste from animal products (Abascal and Regan 2018). Farm animal waste, such as carcasses, hides and skin, feathers, wool, hooves and horns, offal, eggshell, bones, fats, meat trimmings, blood, and other fluids; waste from fishing, other than by-catches, shells, bones, skins, fins, viscera, oils, and blood are examples of industrial processing waste of animal origin (Uranga et al. 2020;Flachowsky, Meyer, and Südekum 2017;Alao et al. 2017). Non-conforming wool and silk fibers are among the textile industry's waste (Abascal and Regan 2018). ...
Article
Significant upsurge in animal by-products such as skin, bones, wool, hides, feathers, and fats has become a global challenge and, if not properly disposed of, can spread contamination and viral diseases. Animal by-products are rich in proteins, which can be used as nutritional, pharmacologically functional ingredients, and biomedical materials. Therefore, recycling these abundant and renewable by-products and extracting high value-added components from them is a sustainable approach to reclaim animal by-products while addressing scarce landfill resources. This article appraises the most recent studies conducted in the last five years on animal-derived proteins' separation and biomedical application. The effort encompasses an introduction about the composition, an overview of the extraction and purification methods, and the broad range of biomedical applications of these ensuing proteins.
... In this regard, replacing HEP with human inedible protein sources, which supports a more circular economy (Van Zanten et al., 2018), is an obvious strategy to ameliorate this. Flachowsky et al. (2017) showed that inclusion of 50% co-products in the concentrate proportion of the diet for beef cattle improved the HEP ratio from 0.7 to 1.3. Similarly, we found that substituting a proportion or all of the barley and soyabean meal in the concentrate ration with by-products, which also better reflects 'commercial' feeding practices in Ireland, resulted in more favourable HEP ratios and ultimately, all of the grazing treatments became net producers of HEP. ...
Article
CONTEXT Demand for environmentally sustainable produced beef, especially ‘grass-fed’, is rising. Bull-beef production is a desirable alternative to steers due to large inherent growth and feed efficiency advantages. Compared to conventional indoor high-concentrate diets, pasture-finishing of bulls is low-cost, but carcass fat cover may not meet market requirements. OBJECTIVE We evaluated the performance, meat quality, profitability, greenhouse gas (GHG) emissions, and human-edible protein (HEP) efficiency of pasture-based purchased suckler bull ‘weanling’-to-beef finishing systems compared to an indoor high-concentrate system. METHODS Suckler bulls, initially offered grass silage and supplementary concentrates during a ‘backgrounding’ phase, were assigned to one of four finishing systems: grazed grass with three levels of barley-based concentrate, 0 (G-0), 0.25 (G-25), and 0.50 (G-50) of predicted dietary dry matter intake, or ad libitum concentrates and grass silage (ALC). The experimental data generated were used to parameterise a whole-farm systems model and the output, profitability and GHG emissions of ‘purchased weanling’-to-beef finishing systems were evaluated. RESULTS AND CONCLUSIONS Total daily dry matter intake was highest for ALC and lowest for G-0. Carcasses from ALC were heavier (406 kg) than all grazing systems; G-50 was heavier (387 kg) than G-25 and G-0 (367 kg). Carcass fat score was higher for ALC (8.3, scale 1–15) than the grazing systems, which were similar (5.0–5.6). Meat eating quality did not differ between systems. Although carcass output per hectare increased by 50% for G-50 and almost-doubled for ALC compared to G-0, gross and net margins were similar for G-0 and G-50, and considerably less for ALC. The GHG emission per animal were lowest for G0 and highest for G50; however, when expressed relative to live-, carcass-, and especially meat weight, emission intensities (kg CO2eq) were lowest for ALC (5.4, 14.9, and 12.2, respectively) and highest for G-0 and G-25 (~9.6, 19.4, and 20.8, respectively). The HEP efficiency ratio was highest for G-0 (0.67) and lowest for ALC (0.21). Compared to a high-concentrate indoor bull finishing system, temperate pasture-based systems had lighter, ‘under-finished’ carcasses but similar meat eating quality, were more profitable, had superior HEP efficiency, but greater GHG emissions when expressed relative to live-, carcass-, and meat weight gain. SIGNIFICANCE Although carcasses were ‘under-finished’ for the grazing systems compared to the high-concentrate indoor system, meat eating quality was similar, implying that, potentially, there is greater scope for beef producers to operate relatively more profitable pasture-based bull-beef finishing. In view of the inverse relationships between profitability, HEP efficiency, and GHG emissions per unit of product among different suckler weanling-to-beef finishing systems, consideration of unavoidable trade-offs is necessary from a beef production, policy and future-research perspective.
Article
A growing world population and ongoing climate change have created a need to find new sources of high quality food, especially protein, that are sustainable and environmentally friendly and help to reduce unsustainable livestock production. Therefore, it is necessary to look for sources of protein from new raw materials or to use existing materials that have not been used on a large scale. The highest protein intake characterizes athletes; thus, the market for high‐protein products should be targeted for them. This paper outlines the main problems associated with protein production to date, mainly from animal sources and some known plant sources such as pulses, which can cause gastrointestinal problems in athletes. The aim of this review was to propose several new/alternative protein sources (Single Cell Protein, edible insects, algae and potato protein) that may have potential for use in food, including food for athletes, while solving the described problems associated with existing protein sources. Insects have the best amino acid composition; microbial and algal proteins have great potential but require further development of technology of application to food products. Potato proteins are of high value and quality but also contain glycoalkaloids. However, using them brings additional economic and environmental benefits.
Article
Full-text available
With an increasing human population access to ruminant products is an important factor in global food supply. While ruminants contribute to climate change, climate change could also affect ruminant production. Here we investigated how the plant response to climate change affects forage quality and subsequent rumen fermentation. Models of near future climate change (2050) predict increases in temperature, CO 2 , precipitation and altered weather systems which will produce stress responses in field crops. We hypothesised that pre-exposure to altered climate conditions causes compositional changes and also primes plant cells such that their post-ingestion metabolic response to the rumen is altered. This “stress memory” effect was investigated by screening ten forage grass varieties in five differing climate scenarios, including current climate (2020), future climate (2050), or future climate plus flooding, drought or heat shock. While varietal differences in fermentation were detected in terms of gas production, there was little effect of elevated temperature or CO 2 compared with controls (2020). All varieties consistently showed decreased digestibility linked to decreased methane production as a result of drought or an acute flood treatment. These results indicate that efforts to breed future forage varieties should target tolerance of acute stress rather than long term climate.
Chapter
Legumes are critical for human nutrition going forward as well as playing a critical role in resilience to assist human populations in dealing with systems shocks. The COVID-19 food shocks of 2020 laid bare the potential long-term need to optimize legume use in global populations. At the same time, there has been an on-going trend towards the increased use of legumes in diverse food applications. Legumes have unique properties that, if exploited, will reduce greenhouse gas emissions, reduce energy consumption, preserve water, increase carbon sequestration while at the same time contributing to soil health through nitrogen fixation. Legume rich diets also provide important health benefits that can result in reduced life-long health care costs. As such, legumes are poised to play an important role in meeting three of the most pressing global challenges of our day – population growth, urbanization, and climate change. Moving forward, coordinated efforts are needed to further expand the role of legumes in food systems globally.
Article
Full-text available
The production of protein from animal sources is often criticized because of the low efficiency of converting plant protein from feeds into protein in the animal products. However, this critique does not consider the fact that large portions of the plant-based proteins fed to animals may be human-inedible and that the quality of animal proteins is usually superior as compared with plant proteins. The aim of the present study was therefore to assess changes in protein quality in the course of the transformation of potentially human-edible plant proteins into animal products via livestock production; data from 30 Austrian dairy farms were used as a case study. A second aim was to develop an approach for combining these changes with quantitative aspects (e.g. with the human-edible feed conversion efficiency (heFCE), defined as kilogram protein in the animal product divided by kilogram potentially human-edible protein in the feeds). Protein quality of potentially human-edible inputs and outputs was assessed using the protein digestibility-corrected amino acid score and the digestible indispensable amino acid score, two methods proposed by the Food and Agriculture Organization of the United Nations to describe the nutritional value of proteins for humans. Depending on the method used, protein scores were between 1.40 and 1.87 times higher for the animal products than for the potentially human-edible plant protein input on a barn-gate level (=protein quality ratio (PQR)). Combining the PQR of 1.87 with the heFCE for the same farms resulted in heFCE×PQR of 2.15. Thus, considering both quantity and quality, the value of the proteins in the animal products for human consumption (in this case in milk and beef) is 2.15 times higher than that of proteins in the potentially human-edible plant protein inputs. The results of this study emphasize the necessity of including protein quality changes resulting from the transformation of plant proteins to animal proteins when evaluating the net contribution of livestock to the human food supply. Furthermore, these differences in protein quality might also need to be considered when choosing a functional unit for the assessment of environmental impacts of the production of different proteins.
Article
Full-text available
Water Footprint Assessment (WFA) is a quickly growing research field. This Special Issue contains a selection of papers advancing the field or showing innovative applications. The first seven papers are geographic WFA studies, from an urban to a continental scale; the next five papers have a global scope; the final five papers focus on water sustainability from the business point of view. The collection of papers shows that the historical picture of a town relying on its hinterland for its supply of water and food is no longer true: the water footprint of urban consumers is global. It has become clear that wise water governance is no longer the exclusive domain of government, even though water is and will remain a public resource with government in a primary role. With most water being used for producing our food and other consumer goods, and with product supply chains becoming increasingly complex and global, there is a growing awareness that consumers, companies and investors also have a key role. The interest in sustainable water use grows quickly, in both civil society and business communities, but the poor state of transparency of companies regarding their direct and indirect water use implies that there is still a long way to go before we can expect that companies effectively contribute to making water footprints more sustainable at a relevant scale.
Book
Full-text available
FULL TEXT can be downloaded via: http://www.fao.org/docrep/018/i3288e/i3288e.pdf Animal production is a significant source of greenhouse gas (GHG) emissions worldwide. Depending on the accounting approaches and scope of emissions covered, estimates by various sources (IPCC, FAO, EPA or others) place livestock contribution to global anthropogenic GHG emissions at between 7 and 18 percent. The current analysis was conducted to evaluate the potential of nutritional, manure and animal husbandry practices for mitigating methane (CH4) and nitrous oxide (N2O) – i.e. non-carbon dioxide (non-CO2) – GHG emissions from livestock production. These practices were categorized into enteric CH4, manure management and animal husbandry mitigation practices. Emphasis was placed on enteric CH4 mitigation practices for ruminant animals (only in vivo studies were considered) and manure mitigation practices for both ruminant and monogastric species. Over 900 references were reviewed; and simulation and life cycle assessment analyses were generally excluded. In evaluating mitigation practices, the use of proper units is critical. Expressing enteric CH4 energy production on gross energy intake basis, for example, does not accurately reflect the potential impact of diet quality and composition. Therefore, it is noted that GHG emissions should be expressed on a digestible energy intake basis or per unit of animal product (i.e. GHG emission intensity), because this reflects most accurately the effect of a given mitigation practice on feed intake and the efficiency of animal production. Enteric CH4 mitigation practices Increasing forage digestibility and digestible forage intake will generally reduce GHG emissions from rumen fermentation (and stored manure), when scaled per unit of animal product, and are highly-recommended mitigation practices. For example, enteric CH4 emissions may be reduced when corn silage replaces grass silage in the diet. Legume silages may also have an advantage over grass silage due to their lower fibre content and the additional benefit of replacing inorganic nitrogen fertilizer. Effective silage preservation will improve forage quality on the farm and reduce GHG emission intensity. Introduction of legumes into grass pastures in warm climate regions may offer a mitigation opportunity, although more research is needed to address the associated agronomic challenges and comparative N2O emissions with equivalent production levels from nitrogen fertilizer. Dietary lipids are effective in reducing enteric CH4 emissions, but the applicability of this practice will depend on its cost and its effects on feed intake, production and milk composition. High-oil by-product feeds, such as distiller’s grains, may offer an economically feasible alternative to oil supplementation as a mitigation practice, although their higher fibre content may have an opposite effect on enteric CH4, depending on basal diet composition. Inclusion of concentrate feeds in the diet of ruminants will likely decrease enteric CH4 emissions per unit of animal product, particularly when above 40 percent of dry matter intake. The effect may depend on type of ‘concentrate’ inclusion rate, production response, impact on fibre digestibility, level of nutrition, composition of the basal diet and feed processing. Supplementation with small amounts of concentrate feed is expected to increase animal productivity and decrease GHG emission intensity when added to all-forage diets. However, concentrate supplementation should not substitute high-quality forage. Processing of grain to increase its digestibility is likely to reduce enteric CH4 emission intensity. Nevertheless, caution should be exercised so that concentrate supplementation and processing does not compromise digestibility of dietary fibre. In many parts of the world, concentrate inclusion may not be an economically feasible mitigation option. In these situations improving the nutritive value of low-quality feeds in ruminant diets can have a considerable benefit on herd productivity, while keeping the herd CH4 output constant or even decreasing it. Chemical treatment of low-quality feeds, strategic supplementation of the diet, ration balancing and crop selection for straw quality are effective mitigation strategies, but there has been little adoption of these technologies. Nitrates show promise as enteric CH4 mitigation agents, particularly in low-protein diets that can benefit from nitrogen supplementation, but more studies are needed to fully understand their impact on whole-farm GHG emissions, animal productivity and animal health. Adaptation to these compounds is critical and toxicity may be an issue. Through their effect on feed efficiency, ionophores are likely to have a moderate CH4 mitigating effect in ruminants fed high-grain or grain-forage diets. However, regulations restrict the availability of this mitigation option in many countries. In ruminants on pasture, the effect of ionophores is not sufficiently consistent for this option to be recommended as a mitigation strategy. Tannins may also reduce enteric CH4 emissions, although intake and milk production may be compromised. Further, the agronomic characteristics of tanniferous forages must be considered when they are discussed as a GHG mitigation option. There is not sufficient evidence that other plant-derived bioactive compounds, such as essential oils, have a CH4-mitigating effect. Some direct-fed microbials, such as yeast-based products, might have a moderate CH4-mitigating effect through increasing animal productivity and feed efficiency, but the effect is expected to be inconsistent. Vaccines against rumen archaea may offer mitigation opportunities in the future, although the extent of CH4 reduction appears small, and adaptation and persistence of the effect is unknown. Manure management mitigation practices Diet can have a significant impact on manure (faeces and urine) chemistry and therefore on GHG emissions during storage and following land application. Manure storage may be required when animals are housed indoors or on feedlots, but a high proportion of ruminants are grazed on pastures or rangeland, where CH4 emissions from their excreta is very low and N2O losses from urine can be substantial. Decreased digestibility of dietary nutrients is expected to increase fermentable organic matter concentration in manure, which may increase manure CH4 emissions. Feeding protein close to animal requirements, including varying dietary protein concentration with stage of lactation or growth, is recommended as an effective manure ammonia and N2O emission mitigation practice. Low-protein diets for ruminants should be balanced for rumen-degradable protein so that microbial protein synthesis and fibre degradability are not impaired. Decreasing total dietary protein and supplementing the diet with synthetic amino acids is an effective ammonia and N2O mitigation strategy for non-ruminants. Diets for all species should be balanced for amino acids to avoid feed intake depression and decreased animal productivity. Restricting grazing when conditions are most favourable for N2O formation, achieving a more uniform distribution of urine on soil and optimizing fertilizer application are possible N2O mitigation options for ruminants on pasture. Forages with higher sugar content (high-sugar grasses or forage harvested in the afternoon when its sugar content is higher) may reduce urinary nitrogen excretion, ammonia volatilization and perhaps N2O emission from manure applied to soil, but more research is needed to support this hypothesis. Cover cropping can increase plant nitrogen uptake and decrease accumulation of nitrate, and thus reduce soil N2O emissions, although the results have not been conclusive. Urease and nitrification inhibitors are promising options to reduce N2O emissions from intensive livestock production systems, but can be costly to apply and result in limited benefits to the producer. Overall, housing, type of manure collection and storage system, separation of solids and liquid and their processing can all have a significant impact on ammonia and GHG emissions from animal facilities. Most mitigation options for GHG emissions from stored manure, such as reducing the time of manure storage, aeration, and stacking, are generally aimed at decreasing the time allowed for microbial fermentation processes to occur before land application. These mitigation practices are effective, but their economic feasibility is uncertain. Semi-permeable covers are valuable for reducing ammonia, CH4 and odour emissions at storage, but are likely to increase N2O emissions when effluents are spread on pasture or crops. Impermeable membranes, such as oil layers and sealed plastic covers, are effective in reducing gaseous emissions but are not very practical. Combusting accumulated CH4 to produce electricity or heat is recommended. Acidification (in areas where soil acidity is not an issue) and cooling are further effective methods for reducing ammonia and CH4 emissions from stored manure. Composting can effectively reduce CH4 but can have a variable effect on N2O emissions and increases ammonia and total nitrogen losses. Anaerobic digesters are a recommended mitigation strategy for CH4 generate renewable energy, and provide sanitation opportunities for developing countries, but their effect on N2O emissions is unclear. Management of digestion systems is important to prevent them from becoming net emitters of GHG. Some systems require high initial capital investments and, as a result, their adoption may occur only when economic incentives are offered. Anaerobic digestion systems are not recommended for geographic locations with average temperatures below 15 °C without supplemental heat and temperature control. Lowering nitrogen concentration in manure, preventing anaerobic conditions and reducing the input of degradable manure carbon are effective strategies for reducing GHG emissions from manure applied to soil. Separation of manure solids and anaerobic degradation pre-treatments can mitigate CH4 emission from subsurface-applied manure, which may otherwise be greater than that from surface-applied manure. Timing of manure application (e.g. to match crop nutrient demands, avoiding application before rain) and maintaining soil pH above 6.5 may also effectively decrease N2O emissions. Animal husbandry mitigation practices Increasing animal productivity can be a very effective strategy for reducing GHG emissions per unit of livestock product. For example, improving the genetic potential of animals through planned cross-breeding or selection within breeds, and achieving this genetic poten tial through proper nutrition and improvements in reproductive efficiency, animal health and reproductive lifespan are effective and recommended approaches for improving animal productivity and reducing GHG emission intensity. Reduction of herd size would increase feed availability and productivity of individual animals and the total herd, thus lowering CH4 emission intensity. Residual feed intake may be an appealing tool for screening animals that are low CH4 emitters, but currently there is insufficient evidence that low residual feed intake animals have a lower CH4 yield per unit of feed intake or animal product. However, selection for feed efficiency will yield animals with lower GHG emission intensity. Breed difference in feed efficiency should also be considered as a mitigation option, although insufficient data are currently available on this subject. Reducing age at slaughter of finished cattle and the number of days that animals are on feed in the feedlot by improving nutrition and genetics can also have a significant impact on GHG emissions in beef and other meat animal production systems. Improved animal health and reduced mortality and morbidity are expected to increase herd productivity and reduce GHG emission intensity in all livestock production systems. Pursuing a suite of intensive and extensive reproductive management technologies provides a significant opportunity to reduce GHG emissions. Recommended approaches will differ by region and species, but will target increasing conception rates in dairy, beef and buffalo, increasing fecundity in swine and small ruminants, and reducing embryo wastage in all species. The result will be fewer replacement animals, fewer males required where artificial insemination is adopted, longer productive life and greater productivity per breeding animal. Conclusions Overall, improving forage quality and the overall efficiency of dietary nutrient use is an effective way of decreasing GHG emissions per unit of animal product. Several feed supplements have a potential to reduce enteric CH4 emission from ruminants, although their long-term effect has not been well-established and some are toxic or may not be economically viable in developing countries. Several manure management practices have a significant potential for decreasing GHG emissions from manure storage and after application or deposition on soil. Interactions among individual components of livestock production systems are very complex, but must be considered when recommending GHG mitigation practices. One practice may successfully mitigate enteric CH4 emission, but increase fermentable substrate for increased GHG emissions from stored or landapplied manure. Some mitigation practices are synergistic and are expected to decrease both enteric and manure GHG emissions (for example, improved animal health and animal productivity). Optimizing animal productivity can be a very successful strategy for mitigating GHG emissions from the livestock sector in both developed and developing countries.
Article
Full-text available
Purpose Livestock already use most global agricultural land, whereas the demand for animal-source food (ASF) is expected to increase. To address the contribution of livestock to global food supply, we need a measure for land use efficiency of livestock systems. Methods Existing measures capture different aspects of the debate about land use efficiency of livestock systems, such as plant productivity and the efficiency of converting feed, especially human-inedible feed, into animal products. So far, the suitability of land for cultivation of food crops has not been accounted for. Our land use ratio (LUR) includes all above-mentioned aspects and yields a realistic insight into land use efficiency of livestock systems. LUR is defined as the maximum amount of human-digestible protein (HDP) derived from food crops on all land used to cultivate feed required to produce 1 kg ASF over the amount of HDP in that 1 kg ASF. We illustrated our concept for three case systems. Results and discussion The LUR for the case of laying hens equaled 2.08, implying that land required to produce 1 kg HDP from laying hens could directly yield 2.08 kg HDP from human food crops. For dairy cows, the LUR was 2.10 when kept on sandy soils and 0.67 when kept on peat soils. The LUR for dairy cows on peat soils was lower compared to cows on sandy soils because land used to grow grass and grass silage for cows on peats was unsuitable for direct production of food crops. A LUR
Article
Because the expansion of cropped areas is ultimately limited and increasingly undesirable, we review recent progress in maize, wheat, rice and soybean yields resulting from improved varieties and agronomic practices.
Book
Human health issues relating to amino acids are extremely broad and include metabolic disorders of amino acid metabolism as well as their presence in food and use as supplements. This book covers the biochemistry of amino acid metabolism in the context of health and disease. It discusses their use as food supplements, in clinical therapy and nutritional support and focuses on major recent developments, highlighting new areas of research that will be needed to sustain further interest in the field.
Article
When talking about 'sustainability' in theory, people often refer to the triple P-concept, where People, Planet and Profit are three pillars of equal value. In practice, these three terms are very often used against each other to prove one's right, depending on one's worldview. If one is looking to sustainable solutions for different problems, it is very important to understand how others see the world and evaluate things. One way to analyze different worldviews is by dividing them by focusing either on their ontological status (reductionism versus holism) or on the epistemological status (subjective versus objective). Combining these two gives us four different worldviews: personal-egocentric (subjective-reductionist), culturalsocial (subjective-holistic), ecological (objective-holistic) and technical (objective-reductionist). For each of those four worldviews, a 3P-ranking can be made. In a personal-egocentric worldview, Profit is the main goal because it pleases the People. Planet is often used within the limits of promoting the other P's, as becomes illustrative in the green-washing by companies. In a cultural-social worldview, People as individuals, as a group or as a species are the major concern, followed by Planet as a necessary biotope for man. Profit is used to make sure that both Planet and People are protected. In an ecological worldview, the Planet as ecosystem is the most important thing, which can only be saved by People and where Profit is the trigger to let People behave in a Planet-saving way. In a technical worldview, mostly People, Planet and Profit are considered as independent entities. This implies that different people have different desires and act different in the same circumstances in order to reach their individual 'sustainable' solution.
Article
Besides the widely discussed negative environmental effects of dairy production, such as greenhouse gas emissions, the feeding of large amounts of potentially human-edible feedstuffs to dairy cows is another important sustainability concern. The aim of this study was therefore to investigate the effects of a complete substitution of common cereal grains and pulses with a mixture of wheat bran and sugar beet pulp in a high-forage diet on cow performance, production efficiency, feed intake, and ruminating behavior, as well as on net food production potential. Thirteen multiparous and 7 primiparous mid-lactation Holstein dairy cows were randomly assigned to 1 of 2 treatments in a change-over design with 7-wk periods. Cows were fed a high-forage diet (grass silage and hay accounted for 75% of the dry matter intake), supplemented with either a cereal grain-based concentrate mixture (CON), or a mixture of wheat bran and dried sugar beet pulp (WBBP). Human-edible inputs were calculated for 2 different scenarios based on minimum and maximum potential recovery rates of human-edible energy and protein from the respective feedstuffs. Dietary starch and neutral detergent fiber contents were 3.0 and 44.1% for WBBP, compared with 10.8 and 38.2% in CON, respectively. Dietary treatment did not affect milk production, milk composition, feed intake, or total chewing activity. However, chewing index expressed in minutes per kilogram of neutral detergent fiber ingested was 12% lower in WBBP compared with CON. In comparison to CON, the human-edible feed conversion efficiencies for energy and protein, defined as human-edible output per human-edible input, were 6.8 and 5.3 times higher, respectively, in WBBP under the maximum scenario. For the maximum scenario, the daily net food production (human-edible output minus human-edible input) increased from 5.4 MJ and 250 g of crude protein per cow in CON to 61.5 MJ and 630 g of crude protein in the WBBP diet. In conclusion, our data suggest that in forage-based dairy production systems, wheat bran and sugar beet pulp could replace common cereal grains in mid-lactation dairy cows without impairing performance, while strongly increasing human-edible feed conversion efficiency and net food production index.
Article
The discussion about the functions of agriculture needs to be broadened beyond the Food-Fuel-Fibre discussion. The '6F' framework has been proposed that incorporates most - if not all - functions of agriculture: Food, Feed, Fuel, Fibre, Flower, and Fun. In an increasingly resource restricted world, agriculture is confronted with an increased demand for each of the 6 Fs. Climate change will increase the 'natural' stress on production in regions that are already less favourable, while population density and civil pressure will increase 'human' stress on production in regions that are well suited for agriculture. Data on water availability, water stress and natural production capacity of different world regions clearly show that (1) many regions rely on irrigation for large parts of their food production (and agricultural production in general); (2) most of those regions experience (or will soon experience) water stress; and (3) the water stress indicators of other regions (e.g. Europe) are equally high, although water seems abundant there. Historically, the largest populations have grown where food production was easiest. For example the coastal areas of the US, Western Europe and Eastern Parts of China are areas with much arable land and large populations. This has resulted in much of the world's most valuable arable land now used for other purposes (habitation, industry, etc), something that is nearly impossible to reverse. Additionally, and quite evident in Western Europe, industrialised societies increase their non-production demands on the rural areas: recreational use of 'the outdoors', pleas for the conservation of 'natural vegetation', etc. Given that higher production is necessary (more people, more consumption), we cannot increase our production apparatus (land, water), and our current apparatus will be under more stress (climate change, environmental protection), the challenge for the future is clear: more for more, with less. Thus, agriculture must intensify (increase the output/input ratio; an improvement of efficiency by better management). The inevitable outcome of the 6F equation is that we have no choice but to intensify production methods and stop tolerating efficiency losses on a global level. The only other option is to strike some of the Fs from the equation.