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A Literature Review of the Value-Added Nutrients found in Grass-fed Beef Products Draft Manuscript

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Abstract

Grass-fed beef, or beef produced from cattle finished on forage only diets, has been touted as a more nutritious beef product. There are a number of reports that show grass-fed beef products contain elevated concentrations of β-carotene and α-tocopherol, increased levels of omega-3 fatty acids, a more desirable omega-3:omega-6 ratio, and increased levels of conjugated linoleic acid (CLA), all substances reported to have favorable biological effects on human health. The purpose of this article is to summarize information currently available to support the enhanced nutrient claim for grass-fed products as well as review the effects these specific nutrients have on human health. Nutrients of interest for Grass-fed Beef ProVitamin A: β-Carotene: Β-carotene, a fat-soluble antioxidant, is derived from the Latin name for carrot, which belongs to a family of natural chemicals known as carotenes or carotenoids. Carotenes produce the yellow and orange color found in fruits and vegetables and is converted to vitamin A (retinol) by the body. While excessive amounts of vitamin A in supplement form can be toxic, the body will only convert as much vitamin A from beta-carotene as it needs, thus beta-carotene is a safe dietary source for vitamin A supplementation. (University of Maryland Medicine, 2002) Vitamin A is a critical fat-soluble vitamin that is important for normal vision, bone growth, reproduction, cell division, and cell differentiation (Stephens et al., 1996). Specifically, it is responsible for maintaining the surface lining of the eyes and also the lining of the respiratory, urinary, and intestinal tracts. The overall integrity of skin and mucous membranes is maintained by vitamin A, creating a barrier to bacterial and viral infection (Semba, 1998; Harbige, 1996). In addition, vitamin A is involved in the regulation of immune function by supporting the production and function of white blood cells (Ross, 1999; Gerster, 1997).
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A Literature Review of the Value-Added Nutrients found in
Grass-fed Beef Products
June 2005 Draft Manuscript
C.A. Daley1, A.Abbott1, P. Doyle1, G. Nader2, and S. Larson2
College of Agriculture, California State University, Chico1
University of California Cooperative Extension Service2
Grass-fed beef, or beef produced from cattle finished on forage only diets, has been
touted as a more nutritious beef product. There are a number of reports that show grass-
fed beef products contain elevated concentrations of β-carotene and α-tocopherol,
increased levels of omega-3 fatty acids, a more desirable omega-3:omega-6 ratio, and
increased levels of conjugated linoleic acid (CLA), all substances reported to have
favorable biological effects on human health. The purpose of this article is to summarize
information currently available to support the enhanced nutrient claim for grass-fed
products as well as review the effects these specific nutrients have on human health.
Nutrients of interest for Grass-fed Beef
ProVitamin A: β-Carotene:
Β-carotene, a fat-soluble antioxidant, is derived from the Latin name for carrot, which
belongs to a family of natural chemicals known as carotenes or carotenoids. Carotenes
produce the yellow and orange color found in fruits and vegetables and is converted to
vitamin A (retinol) by the body. While excessive amounts of vitamin A in supplement
form can be toxic, the body will only convert as much vitamin A from beta-carotene as it
needs, thus beta-carotene is a safe dietary source for vitamin A supplementation.
(University of Maryland Medicine, 2002)
Vitamin A is a critical fat-soluble vitamin that is important for normal vision, bone
growth, reproduction, cell division, and cell differentiation (Stephens et al., 1996).
Specifically, it is responsible for maintaining the surface lining of the eyes and also the
lining of the respiratory, urinary, and intestinal tracts. The overall integrity of skin and
mucous membranes is maintained by vitamin A, creating a barrier to bacterial and viral
infection (Semba, 1998; Harbige, 1996). In addition, vitamin A is involved in the
regulation of immune function by supporting the production and function of white blood
cells (Ross, 1999; Gerster, 1997).
The current recommended intake of vitamin A is 3,000-5,000 IU for men and 2,300-
4,000 IU for women (National Institute of Health Clinical Center, 2002; Harvard School
of Public Health) which is equivalent to 900 – 1500 µg (micrograms) (Note: DRI (dietary
reference intake) as reported by the Institute of Medicine for non-pregnant/non-lactating
adult females is 700 µg and males is 900 µg /day or 2,300 - 3,000 IU (assuming
2
conversion of 3.33 IU/ug). While there is no RDA (Required Daily Allowance) for beta-
carotene or other pro-vitamin A carotenoids, the Institute of Medicine report suggests that
consuming 3 mg of beta-carotene daily to maintain plasma beta-carotene in the range
associated with normal function and a lowered risk of chronic diseases (NIH: Office of
Dietary Supplements).
Descalzo et.al., 2005, found pasture-fed steers incorporated significantly higher amounts
of β-carotene into muscle tissues as compared to grain-fed animals. Concentrations
ranged from 0.63 – 0.45 µg/g and 0.06 – 0.5 µg/g for meat from pasture and grain-fed
cattle respectively, a 10 fold increase in β-carotene levels for grass-fed beef. Similar data
is reported by Simonne, et.al., 1996; Yang et.al., 2002a; and Wood and Enser, 1997,
presumably due to the high β-carotene content of fresh forage as compared to cereal
grains (Simonne et al., 1996).
Vitamin E: Alpha-tocopherol:
Vitamin E is also a fat-soluble vitamin that exists in eight different forms with powerful
antioxidant activity, the most active being α-tocopherol (Pryor, 1996). Antioxidants
protect cells against the effects of free radicals. Free radicals are potentially damaging
by-products of the body’s metabolism that may contribute to the development of chronic
diseases such as cancer and cardiovascular disease.
Preliminary research shows vitamin E supplementation may help prevent or delay
coronary heart disease (Lonn and Yusuf, 1997; Jialal and Fuller, 1995; Stampfer et al.,
1993; Knekt et al., 1994). Vitamin E may also blocks the formation of nitrosamines,
which are carcinogens formed in the stomach from nitrites consumed in the diet. It may
also protect against the development of cancers by enhancing immune function (Weitberg
and Corvese, 1997). In addition to the cancer fighting affects, there are some
observational studies that found lens clarity (a diagnostic tool for cataracts) was better in
patients who regularly use vitamin E (Leske et al., 1998; Teikari et al., 1997).
The current recommended intake of vitamin E is 22 IU (natural source) or 33 IU
(synthetic source) for men and women (National Institute of Health Clinical Center,
2002; Harvard School of Public Health; ARS, United States Department of Agriculture,
2000) is necessary for biological activity. Twenty-two international units is equivalent to
15 milligrams by weight.
The concentration of natural α-tocopherol (vitamin E) found in grain-fed beef is
approximately 2.0 µg/g of muscle whereas pasture fed beef ranges from 5.0 to 9.3 µg/g of
tissue depending on the type of forage made available to the animals (Yang et al., 2002b,
Arnold et al., 1992, Faustman et al., 1998). Forage finishing increases α-tocopherol levels
3-fold over conventional beef and well within range of the muscle α-tocopherol levels
needed to extend the shelf-life of retail beef (McClure et al., 2002). Vitamin E, α-
tocopherol, acts post-mortem to delay oxidative deterioration of the meat, i.e., a process
by which myoglobin to converted into brown metmyoglobin, producing a darkened
appearance to the meat.
3
Omega 3: Omega 6 fatty acids:
Omega-3 fatty acids are considered essential fatty acids, which means that they are
essential to human health but cannot be manufactured by most mammalian species. For
this reason, omega-3 fatty acids must be obtained from food.
Essential fatty acids (EFAs) are polyunsaturated and grouped into two families, the
omega-6 EFAs and the omega-3 EFAs. Although there are just minor differences in their
molecular structure the two EFA families act very differently in the body. While the
metabolic products of omega-6 acids promote inflammation, blood clotting, and tumor
growth, the omega-3 acids act entirely opposite. However, it is important to maintain a
balance of omega-3 and omega-6 in the diet as these two substances work together to
promote health.
There are 3 major types of omega-3 fatty acids that are ingested in foods and used by the
body: α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid
(DHA). Once eaten, the body converts ALA to EPA and DHA, the two types of omega-3
fatty acids that are most readily used by the body.
According to the University of Maryland, an inappropriate balance of these essential fatty
acids (high omega-6/omega-3 ratio) contributes to the development of disease while a
proper balance helps maintain and even improves health. A healthy diet should consist of
roughly one to four times more omega-6 fatty acids than omega-3 fatty acids. The typical
American diet tends to contain 11 to 30 times more omega-6 fatty acids than omega-3
and many researchers believe this imbalance is a significant factor in the rising rate of
inflammatory disorders in the United States (Simopoulos, 1991; Simopoulos 2002).
Scientists discovered the many benefits of EPA and DHA in the early 1970’s when
Danish physicians observed that Greenland Eskimos had an exceptionally low incidence
of heart disease and arthritis despite the fact that they consumed a high-fat diet. More
recent research has established that EPA and DHA play a crucial role in the prevention of
atherosclerosis, heart attack, depression and cancer (Simopoulos, 1991; Simopoulos
2002; Connor, 2000). In addition, omega-3 consumption by individuals with rheumatoid
arthritis has led to the reduction or discontinuation of their ordinary treatment (Kremer,
1989; DiGiacomo, 1989).
The human brain has a high requirement for DHA, low DHA levels have been linked to
low brain serotonin levels, which are connected to an increased tendency for depression
and suicide. Several studies have established a clear association between low levels of
omega-3 fatty acids and depression. In fact, countries with a high level of omega-3
consumption have fewer cases of depression, decreased incidence of age-related memory
loss as well as a reduction in impaired cognitive function and a lower risk of developing
Alzheimer’s disease (Kalmijn et al., 1997a; Kalmijn et al., 1997b; Yehuda et al., 1996;
Hibbeln, 1998; Hibbeln et al., 1995; Stoll et al., 1999; Calabrese et al., 1999; Laugharne
et al., 1996).
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There is some consensus among leading nutritionists who consider increases in chronic
disease as no accident; they believe it is directly related to the change in our dietary
patterns over the last 200 years. Our ancestors lived on an omega-6:omega-3 ratio of 1:1,
while our current dietary habits are closer to 10-20:1 (Simopoulos, 1991; Pepping, 1999).
Researchers believe the ideal omega-6 intake should be no more than 4-5 times that of
our omega-3 intake. The National Institutes of Health recently published recommended
daily intakes of fatty acids, specific recommendations include 650 mg of EPA and DHA,
2.22 g/day of alpha-linolenic acid and 4.44 g/day of linoleic acid. However, the Institute
of Medicine has recommended DRIs for linoleic acid (omega-6) at 12- 17 g and 1.1-1.6 g
for α-linolenic acid (omega-3) for adult women/men.
As with the human diet, cattle feed or the composition of the ration has a significant
effect on the fatty acid profile of the final beef product. Cattle fed primarily grass
enhanced the omega-3 content of beef by 60% and also produces a more favorable
omega-6 to omega-3 ratio. Conventional beef contains a 4:1 omega 6:3 ratio while grass-
only diets produce a 2:1 omega 6:3 ratio (French et al., 2000; Duckett et al., 1993;
Marmer et al, 1984; Wood and Enser, 1997). Table 1 which shows the effect of ration on
omega 6 and omega 3 fatty acid concentrations in beef, data is reported as g/100g of total
fatty acids in meat produced from the various feeding regimes. The all grass diet
produces the highest omega-3 concentration within the meat product while omega-6
levels stay fairly constant regardless of grain to grass ratio.
Table 1.
Essential Fatty
Acides by diet
(g/100g of fatty
acid)
Treatment
Fatty Acid
Grass
silage +
4kg conc.
1kg hay +
8 kg conc.
6 kg grass
(DM basis) +
5 kg of conc.
12 kg grass
(DM basis)
+ 2.5 kg of
conc.
22 kg of
grass DM
n-6 fatty acids 2.96
3.21
3.12
3.04
3.14
n-3 fatty acids .91y .84y 1.13x
1.25wx 1.36w
n6:n3 ratio 3.61w 4.15w 2.86x 2.47x 2.33x
w,x,y,z Means within rows with common superscripts are not significantly different
(P>.05) French, et al., 2000.
Rule et al., 2002, reported similar results in a direct comparison of n-3 and n-6 EFAs for
cattle on grain vs. grass, i.e., grass-fed cattle produced higher percentages of omega 3
within the lipid fraction than grain-fed contemporaries.
5
Table 2. EFAs by diet (as %
of total fatty acids)
Grass-fed
Grain-fed
n-6 fatty acids 5.66 %a 3.92 %a
n-3 fatty acids 2.90 %b 0.64 %c
n6:n3 ratio 1.95d 6.38e
a,b,c,d,e
Means within rows with common superscripts are not significantly different (P>.01) Rule, et al., 2002.
The amount of lipid per serving is highly variable and depends on the feeding regime,
genetics and actual cut of beef, however when lipid content is standard (as in hamburger),
a serving of grain-fed beef at 10% fat would provide 84 milligrams of omega-3 in a 100
gram serving according to French et al., 2000 (.84 g n-3/100g lipid; 100g serving at 10%
lipid = 10g fat/serving; roughly 84 mg n-3). The same hamburger from grass-fed beef
would produce 136 mg n-3/serving.
In general, grass-fed cattle are slaughtered at lighter weights than grain fed beef,
producing leaner (lower fat) carcasses overall. Thus, whole cuts from grass-fed carcasses
will not provide the same quantities of n-3 as described for hamburger at a constant %
fat. Leaner carcasses have the advantage of an overall lower percent fat and a higher
proportion of favorable unsaturated fatty acids. However, ultra lean carcasses (less than
.3 inches of backfat) lead to cold shortening and reduced tenderness, in addition, lowered
fat levels impact eating quality such as flavor and juiciness.
Conjugated Linoleic Acid (CLA):
The term conjugated linoleic acid and its acronym CLA is a group of polyunsaturated
fatty acids found in beef, lamb, and dairy products that exist as a general mixture of
positional and geometric conjugated isomers of linoleic acid (Sehat et al., 1999). These
compounds are produced in the rumen of cattle and other ruminant animals during the
microbial biohydrogenation of linoleic and linolenic acids by an anaerobic rumen
bacterium Butyrivibrio fibrisolvens. (Pariza et al., 2000).
Nine different positional and geometrical
isomers result from this process, of which,
cis-9, trans-11 is the most abundant and is the
biologically active form. Cis-9, trans-11
makes up 75% or more of the total CLA in
beef (Ip, et al, 1994; Chin et al., 1992; Parodi,
1997).).
Over the past two decades numerous health
benefits have been attributed to CLA in
experimental animal models including actions
to reduce carcinogenesis, atherosclerosis,
onset of diabetes, and fat body mass.
6
The anti-atherosclerotic evidence was first reported in CLA treated mice by Clement Ip
in 1994. Ip and coworkers showed CLA levels as low as 0.05 percent of the diet can have
a beneficial effect in mice. A level of 0.5 percent reduced the total number of mammary
tumors by 32 percent. These results also demonstrated that CLA administered through a
dietary route was effective in providing protection against cancer (Ip et al., 1994).
In a 1996 supplemental feeding study, Carol Steinhart showed a lower level of LDL
(“bad”) cholesterol in both rabbits and hamsters treated with oral CLA, resulting in
significantly less plaque formation in the aortic artery of treated animals (Steinhart,
1996). Presumably this reduction in plaque formation would therefore reduce the
incidence of heart disease. Likewise, David Kritchevsky demonstrated that CLA levels
as low as 0.1 percent of the diet can have beneficial effects by inhibiting atherogenic
activity in rabbits (Kritchevsky et al., 2000). This particular study also showed a 30
percent regression of established atherosclerosis with a CLA level of 1 percent of the
diet.
There is considerable data that demonstrates how CLA modulates body composition by
reducing the accumulation of adipose tissue, primarily in experimental animals. In mice,
rats, pigs, and now humans, dietary CLA has been shown to reduce adipose tissue depots
(Dugan et al., 1999; Park et al., 1997; Sisk et al., 2001; Smedmen et al., 2001) Although
there is some controversy within the human data, it is likely that dose, duration, isomeric
composition, age and gender influence the outcome of CLA supplementation. For
instance, lower doses (3g/day: Blankson et al., 2000) had little effect while larger doses
(3.4 – 6.0 g/day) significantly reduced fat mass in humans (Zambell et al., 2000).
These ultra high doses of synthetic CLA may produce ill side-effects, with the most
common being of gastrointestinal origin, although there have been reports of adverse
changes to glucose/insulin metabolism and liver function in some animal studies
depending on the dose and the isomer studied (Tsubooyama-Kasaoka et al., 2000; Delany
et al., 1999; Clement et al., 2002; Roche et al., 2002). In humans, insulin resistance was
reported with ingestion of a supplement enriched with the t10,c12 isomer, but not with a
mixed preparation of predominantly c9,t11 and t10,c12 CLA isomers (Riserus et al.,
2002).
CLA is found naturally in a variety of ruminant meats (French, et al, 2000) and dairy
products (Dhiman, et al, 1999), due to the anaerobic activity of the rumen bacterium
Butyrivibrio fibrisolvens. This rumen organism is responsible for the biohydrogenation of
linoleic and linolenic acids into the conjugated isomers referred to as CLA. Because
linoleic and linolenic acid is a precursor, diets rich in these compounds increase the
concentration of the CLA within the fat depot of the animal. Lush green forages are
particularly high in this precursor, therefore, grass-fed ruminant species have been
shown to produce 2 to 3 times more CLA than ruminants fed in confinement on
concentrate-only diets (French, et al, 2000; Duckett, et al, 1993; Rule, et al, 2002;
Mandell et al, 1998).
7
Conjugated Linoleic Acid (g/100g or g/3.50oz.)
Study Feedlot/Concentrate Range/Grass Amount Increased
French, 2000 .37 z 1.08 w 2.92 X
Duckett, 1993 .82 c 2.2 d 2.69 X
*Rule, 2002 .26 e .41 c 2.04 X
On average, grass-fed beef will provide approximately 123 mg of CLA for a standard
hamburger at 10% fat. The same hamburger produced from grain-fed beef would provide
48.3 mg. (i.e., grass-fed = 1.23 g CLA/ 100g lipid; 12.3 mg/g lipid; 10% lipid/serving =
123 mg CLA).
Research to date would support the argument that grass-fed beef is higher in Vitamin A,
Vitamin E, CLA and Omega 3 when lipids are compared on a gram of fatty acid/gram of
lipid basis. Little work has been done to compare grass-fed cattle to grain-fed at a
constant degree of fatness, most studies harvest cattle after a specific number of days on
feed rather than processing cattle at a logical slaughter endpoint based on degree of
fatness. Because grass-fed cattle are fed lower energy diets, they tend to fatten more
slowly and are slaughtered at a lower % body fat. As percent body fat decreases so does
the concentration of these important lipids like CLA and omega-3 in whole cuts of beef.
Maintaining the favorable lipid profile:
Maintaining the favorable lipid profile in grass-fed beef requires a high percentage of
forages, the more green and fresh the forage, the higher the C18:2 α-linoleic and α-
linolenic acid precursor will be available for n-3 and CLA synthesis. Dried, cured forages
will have a lower amount of precursor, with a slightly lower level of functional lipids in
the final product. However, if cattle are switched over to a diet predominantly composed
of cereal grains, a significant amount of FA remodeling takes place in the intramuscular
fat fraction (marbling or neutral lipid fraction viewed as fat flecks throughout the meat.)
will take place within 30 days of diet transition (Duckett, et al., 1993).
To maintain high functional lipid concentrations, producers must feed forages rich in
C18:2 is to maintain a high concentration of pre-curser compounds in the ration. The
precursor for the n-3 series is α-linolenic (LNA: C18:3 n-3), the higher the concentration
of C18:3 n-3 in the ration, the more n-3 fatty acids will be found in the final product.
Fresh forages have 10 to 12 times more C18:3 than cereal grains (French, et al., 2003).
Likewise, the precursor fatty acid for CLA is linoleic acid (LA: C18:2n-3), the higher the
concentration LA the diet, the higher the concentration of CLA in the meat.
8
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... However, Omega 3 levels in all indigenous breeds were high (Kho-Lan = 6.25%, Kho-Chon = 6.26%, and Kho-Esarn = 2.37%) compared with Bos taurus (2.90% for grass fed and 0.64% for grain fed animals (Daley et al., 2009). Omega 3 beef was different from typical beef in that it was obtained by grass feeding while typical beef is most often obtained through grain feeding. ...
... A proper balance between Omega 3 and Omega 6 fatty acids helps to maintain and even to improve health. A healthy diet should consist of roughly one to four times more omega 6 fatty acids than omega 3 fatty acids (Daley et al., 2009). ...
... They are produced in the rumen of cattle and other ruminants during microbial biohydrogenation of linoleic and linolenic acids by the anaerobic rumen bacterium Butyrivibrio fibrisolvens (Pariza et al., 2000). Over the past two decades numerous health benefits have been attributed to CLA in experimental animal models including actions to reduce carcinogenesis, atherosclerosis, the onset of diabetes, and fat body mass (Daley et al., 2009). ...
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The productivity veterinary services, which include disease control and management of reproduction, udder health and nutrition, are not practised in smallholder dairy farms although they are proven to increase milk production in large dairy herds. We introduced an on-farm service with the participation of farmer associations where individual veterinarians made a scheduled visit to perform preventive and emergency cattle health care, reproduction, and feed management. We examined 1 849 animals on 862 farms guided by specific forms, a breeding calendar and a herd summary generated from data of the initial visit by using a Microsoft Access based computer application. On average, 53% anoestrous heifers and 67% anoestrous cows resumed their oestrous cycle when treated with hormones, vitamin AD3E or nutritional supplements. Forty percent of cows with uterine infections conceived when treated with intrauterine antibiotics or prostaglandin F2α (PGF2α) was injected intramuscularly before artificial insemination (AI) was done. When GnRH was injected at the time of AI, 73% repeat breeder cows conceived. About 78% of cows recovered from mastitis and 88% of sick animals recovered when treatment was given based on clinical diagnosis. A database on common cattle diseases was established. More than 75% of farms that received the service had an income increase ranging from US$1 to US$40.7/month/cow. Productivity veterinary services can increase farmers’ incomes and the number of cows available for breeding.
... Hydroponic fodder supplementation to a corn grain/cob diet-based beef showed 7.5% increase in weight gain and 23% less feed consumption [117]. Moreover, some studies on beef cattle also revealed that feeding fresh forages has multiple benefits over grain feeding in producing healthier meat: a more desirable ω-3 to ω-6 ratio increased levels of conjugated linoleic acid, and elevated levels of β-carotene (pro-vitamin A) and α-tocopherol (vitamin E) [29,30,131]. ...
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Hydroponic fodder production in controlled environment (CE) settings have gained more focus in recent years due to the shortage of agricultural land for food production and the adverse effect of climate changes. However, the operation costs and dry matter issues are the major concerns for the sustainability of fodder production in the CE. This study provides a comprehensive literature review on techniques and control strategies for indoor environments and watering that are currently used and could be adopted in the future to achieve the economic and environmental sustainability of controlled environment fodder production (CEFP). The literature indicates fodder production in the modular system is becoming popular in developed countries, and low-tech systems like greenhouse are more prevalent in developing countries. The optimum temperature and RH range between 16-27°C and 70-80% to get efficient biomass yield; however, minimal research has been conducted to optimize the indoor temperature and relative humidity (RH) for efficient and higher efficiency fodder production. Besides, the water-saving techniques and optimal lighting spectrum need to be studied extensively. Automating and monitoring in CEFP system could reduce operating costs and improve quality and yield. Overall, this industry might have great potential for livestock production. Still, more strong research needs to be conducted to answer nutritional concerns and reduce the capital and operating costs for CEFP.
... Modern Western diets typically have ratios of omega -6 to omega-3 in excess of 10 to 1 , some as high as 30 to 1, partly due to corn oil which has an omega-6 to omega -3 ratio of 49 : 1 . The optimal ratio is thought to be 4:1 or lower (Daley, et al., 2004 andSimopoulos 2002). ...
... Modern diets typically have ratios of omega-6 to omega-3 in excess of 10 to 1, or 30 to 1. Corn oil has an omega-6 to omega-3 ratio of 49:1. The optimal ratio is thought to be 4 to 1 or lower [9,10]. A high intake of omega-6 fatty acids may increase the likelihood of developing breast cancer [11], prostate cancer [12]. ...
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Eighty adult albino rats were used in Present study to access the correlation between the administration of corn oil, truffle oil or wheat germ oil beside fatty acid synthesis enzymes and serum lipid profile. Significant increase in the level of total lipids, triacylglycerol (TAG), cholesterol, low density lipoprotein (LDL-c) with decrease in the level of high density lipoprotein (HDL-c) in the groups treated with corn oil. Where, truffle oil and wheat germ oil showed significant increase in the level of HDL-c. Significant decrease in the level of Acetyl-coA-carboxylase (ACC), Citrate cleavage enzyme (CCE), Malic dehydrogenase (ME) and Isocitrate dehydrogenase (ICDH) with a significant increase in the enzymatic activity of 6-phosphogluconate dehydrogenase (6-PGDH) in hepatic tissues was also detected. On the other hand, in peripheral adipose tissue, there were an increase in the enzymatic activities of all lipogenic enzymes in the groups treated with corn oil with nearly no change in the groups treated with truffle and wheat germ oil beside, a significant increase in the level of 6-PGDH only in the group treated with germ oil. The result of the present study indicate that the use of these oils could be a valuable source for the protection against coronary heart diseases and associated cardiovascular diseases (CVD) in animals and human.
... Generally, the consumption of n−3, but not n−6 has been advised (LESKANICH and NOBLE, 1997). In the present study, the Σn6: Σn3 levels (4.34-5.37) of the breast and leg muscles in different fattening groups were similar to the reports of 4:1 by SIMOPOULOS (2004) and DALEY et al. (2005), but the Σn6: Σn3 levels in the present study were lower than those reported (8.59-9.08) by OKRUSZEK (2012) for Rypinska and Garbosa geese. ...
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The objective of this study was to investigate the effect of different fattening systems on the technological properties and fatty acid composition of goose meat. The geese were divided into four groups, with six geese in each group: 1) pasture grass, 2) pasture grass + barley, 3) pasture grass + commercial grower feed, and 4) commercial grower feed. During the first 4 weeks of the study, the goslings were fed with a concentrate diet. From 5th to 14th weeks the different feeding systems have been applied. All the geese were slaughtered when they were 14 weeks old to collect meat samples. The different fattening systems had a significant (P≤0.05) effect on the pH15 and drip loss of leg muscles, and on the cooking loss of breast muscles. The fatty acid compositions in the breast and leg muscle of the geese were not statistically different between the groups in the different fattening systems (P>0.05). However, the Σ −polyunsaturated fatty acid (ΣPUFA) content, Σ − monounsaturated fatty acid (ΣMUFA) content, and nutritive value index (NVI) were higher in the breast muscles than in the leg muscles in the pasture grass group (P≤0.05). The NVI of the leg muscles was higher than that of the breast muscles in the pasture grass + barley group (P≤0.05). The Σ −saturated fatty acid (ΣSFA) and the thrombogenic index (TI) were higher in the breast muscles than in the leg muscles in the pasture + grower group (P≤0.05). In conclusion, the different fattening systems affected some technological properties of the meat. Research is needed on the deposition and digestion of fatty acids and energy metabolism with different fattening systems in geese.
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In order to study of fattening potential of lambs by pasturing barley forage, 21 Atabay (Dalagh) ram lambs, with initial body weight 22.5±0.4 selected and used in 90 days feeding experiment. A completely randomized design with 3 treatments and 7 replications was used. The lambs were fed diets include: (1) fattening diet, (2) 1 month grazing + 2-month fattening diet, (3) 2-month grazing +1 month fattening diet. The effects of treatments on total weight and daily feed intake of the lambs were not significant, however, the average daily gain of lambs in the first, second and third months of the experiment had a significant difference between treatments (P>0.05). Carcass efficiency, Carcass weight, Carcass length, eye muscle area and cut fat thickness was not affected by treatments. Lambs grazed one and two months had the most leg weight respectively, that were significant different with the fattening diet (P>0.05). Flank and brisket weight were significantly higher in 1-month grazing treatment than others (P>0.05).
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The objective of this study was to determine the effects of dietary n-6/n-3 polyunsaturated fatty acid (PUFA) ratios on the organ indexes, and histological and ultrastructures of organs including liver, spleen and thymus in 70-day-old Yangzhou goslings. One-hundred and sixty 21-day-old Yangzhou goslings were randomly divided into 4 groups and fed 4 diets varying in the n-6/n-3 PUFA ratio from 3:1 up to 12:1. After 1-week acclimation, the feeding experiment lasted for 6 weeks. At the end of the experimental period, goslings were slaughtered and the liver, spleen and thymus were weighed, and their histological and ultrastructures were examined. The results showed that the organ indices in the 3:1 group were remarkably higher than in the other three groups, whereas the mitochondrial square did not differ among four groups. The histological and ultrastructures of the liver, spleen and thymus were not affected by the diets with the lower n-6/n-3 PUFA ratios (3:1 and 6:1). However, feeding diets with the higher n-6/n-3 PUFA ratios (9:1 and 12:1), the nuclear chromatin was concentrated and marginalized; the cell membrane was contracted inwardly and disrupted; the mitochondrial membrane was damaged to some degree. In conclusion, the diet containing higher content of n-3 PUFA might improve immune capacity of goslings the animal by accelerating the growth and maintaining cellular structures of organs like liver, spleen and thymus.
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1 Acevedo is a graduate student and Lawrence is a professor (jdlaw@iastate.edu) in the Department of Economics and Margaret Smith is member of the Value-added Agriculture Program, Iowa State University.
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Conjugated linoleic acid (CLA) is a heterogeneous group of positional and geometric isomers of linoleic acid. This study demonstrates the divergent effects of the cis-9 trans-11 (c9,t11-CLA) and trans-10 cis-12 (t10,c12-CLA) isomers of CLA on lipid metabolism and nutrient regulation of gene expression in ob/ob mice. The c9, t11-CLA diet decreased serum triacylglycerol (P = 0.01) and nonesterified fatty acid (NEFA) (P = 0.05) concentrations, and this was associated with reduced hepatic sterol regulatory element-binding protein-1c (SREBP-1c; P = 0.0045) mRNA expression, coupled with reduced levels of both the membrane-bound precursor and the nuclear forms of the SREBP-1 protein. C9,t11-CLA significantly reduced hepatic LXRalpha (P = 0.019) mRNA expression, a novel regulator of SREBP-1c. In contrast, c9,t11-CLA increased adipose tissue SREBP-1c mRNA expression (P = 0.0162) proportionally to the degree of reduction of tumor necrosis factor alpha (TNF-alpha) mRNA (P = 0.012). Recombinant TNF-alpha almost completely abolished adipose tissue SREBP-1c mRNA expression in vivo. The t10,c12-CLA diet promoted insulin resistance and increased serum glucose (P = 0.025) and insulin (P = 0.01) concentrations. T10, c12-CLA induced profound weight loss (P = 0.0001) and increased brown and white adipose tissue UCP-2 (P = 0.001) and skeletal muscle UCP-3 (P = 0.008) mRNA expression. This study highlights the contrasting molecular and metabolic effect of two isomers of the same fatty acids. The ameliorative effect of c9,t11-CLA on lipid metabolism may be ascribed to reduced synthesis and cleavage of hepatic SREBP-1, which in turn may be regulated by hepatic LXRalpha expression.
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Purpose: To study if long-term supplementation with alpha-tocopherol or betacarotene is associated with cataract prevalence and severity. Methods: An end-of-trial random sample of 1828 participants from the randomized, double-blind, placebo-controlled clinical trial the alpha-tocopherol, beta-carotene cancer prevention study. The alpha-tocopherol, beta-carotene cancer prevention study was originally designed to examine whether supplementation, with alpha-tocopherol or beta-carotene would reduce the incidence of lung cancer in male smokers. The participants for this study lived in Helsinki City or Uusimaa province and were at entry to the alpha-tocopherol, beta-carotene cancer prevention study 50 to 69 years old and smoked at least 5 cigarettes per day They received alpha-tocopherol 50 mg/day, beta-carotene 20 mg/day, a combination of the two, or placebo supplements for 5 to 8 years (median 6.6 years). Outcome measures were: cortical, nuclear, and posterior subcapsular cataract, differentiated and quantified with lens opacity classification system (LOCS II). Lens opacity meter provided a continuous measure of cataract density. Results: Supplementation with alpha-tocopherol or beta-carotene was not associated with the end-of-trial prevalence of nuclear (odds ratio 1.1 and 1.2, respectively), cortical (odds ratio 1.0 and 1.3, respectively), or posterior subcapsular cataract (odds ratio 1.1 and 1.0, respectively) when adjusted for possible confounders in logistic model, Neither did the median lens opacity meter values differ bet tr een the supplementation groups, indicating no effect of alpha-tocopherol or beta-carotene on cataract severity. Conclusion: Supplementation with alpha-tocopherol or beta-carotene for 5 to 8 years does not influence the cataract prevalence among middle-aged, smoking men.
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Conjugated linoleic acid (CLA) is a group of octadecadienoic acids that are naturally present in the highest concentrations in foods originating in ruminant animals, and dairy products such as milk. Especially large numbers of CLA polymers have been detected in beef, lamb and milk fat. Results from many in vitro and animal studies, though conflicting, have suggested that CLA supplementation may have beneficial effect on obesity, weight management, cancer, diabetes and atherosclerosis. This article provides a brief overview on the functionality, safety and toxicity of CLA as described in literature.
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The aim of this experiment was to quantify the relationship between autumn grass supply and concentrate supplementation level on grass intake and animal performance. One hundred and ten continental steers (567 kg) were assigned to 10 treatments. The experimental design was a three grass allowances (6, 12 and 18 kg dry matter (DM) per head daily) by three concentrate levels: (0, 2·5 and 5 kg per head daily) factorial with a positive control group offered concentrates ad libitum and no grass. Grass allowance was offered daily and concentrates were given individually. The experiment began on 22 August and all animals were slaughtered after a mean experimental period of 95 days. Grass intake was calculated using the n-alkane technique and diet digestibility using ytterbium acetate as an indigestible marker. There was an interaction ( P < 0·05) between grass allowance and concentrate level for grass intake. At the low grass allowance there was no effect of offering animals supplementary concentrates on grass intake, at the medium and high grass allowances, supplementary concentrates reduced grass intake by 0·43 and 0·81 kg DM respectively per kg DM concentrate offered. Increasing grass allowance increased ( P < 0·001) complete diet organic matter (OM) digestibility at all concentrate levels and supplementary concentrates increased ( P < 0·001) complete diet OM digestibility only at the low grass allowance. Both offering animals supplementary concentrates ( P < 0·001) and increasing daily grass allowance ( P < 0·001) increased their carcass growth rate. Relative to the animals offered the low grass allowance and no concentrate, supplementing with concentrate increased carcass growth by 116 g/kg concentrate DM eaten whereas increasing the grass allowance, increased carcass growth by 38 g/kg DM grass eaten. As a strategy for increasing the performance of cattle grazing autumn grass, offering supplementary concentrates offers more scope than altering grass allowance.
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Feeding conjugated linoleic acid (CLA) has recently been shown to repartition fat to lean in pigs. The present study was undertaken to determine if feeding CLA affects pork quality. Pigs were fed a cereal-based diet containing either 2% CLA or 2% sunflower oil. Fifty-four pigs (27 gilts and 27 barrows) were fed per diet, and diets were fed from 61.5 to 106 kg liveweight. Diet did not affect postmortem longissimus thoracis (LT) glycogen utilization, lactate accumulation, or pH decline. Conjugated linoleic acid fed pigs had slightly higher LT temperatures at 3 h postmortem (+1.15°C; P < 0.05), but subsequent LT shear force, drip loss and soluble protein levels were unaffected. Diet did not affect subjective LT scores for structure or color, but objective color measurements indicated LT from CLA-fed pigs had slightly higher chroma (color saturation) values (+0.84; P < 0.05). Longissimus thoracis from CLA-fed pigs also had increased subjective marbling scores (P < 0.01) and increased petroleum-ether-extractable intramuscular fat (+22%; P < 0.01). Diet did not affect any measured palatability characteristic (initial and overall tenderness, juiciness, flavor desirability, flavor intensity, connective tissue amount, overall palatability; P > 0.05). Feeding 2% dietary CLA to pigs, therefore, shows some potential for improving pork composition by increasing intramuscular fat, while having no detrimental effect on pork quality.
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Conjugated dienoic derivatives of linoleic acid (CLA), shown to be anticarcinogenic in several animal models, are present in many natural food sources. However, few quantitative data on CLA in food are available. An improved method for quantifying CLA was developed. The method was used to produce a data base of more than 90 food items including meat, poultry, seafood, dairy products, plant oils, and infant and processed foods. The principal dietary sources of CLA are animal products. In general, meat from ruminants contains considerably more CLA than meat from nonruminants, with veal having the lowest and lamb the highest (2.7 vs 5.6 mg CLA/g fat). Foods derived from nonruminant animals were far lower in CLA content except for turkey. Seafood contained low amounts of CLA, ranging from 0.3 to 0.6 mg CLA/g fat. By contrast dairy products (milk, butter, and yogurt) contained considerable amounts of CLA. Natural cheeses were also high in CLA. Among cheeses, those which were aged or ripened more than 10 months had the lowest CLA content. CLA concentrations in an assortment of processed cheeses did not vary much (avg 5.0 mg CLA/g fat). Plant oils contained far less CLA, ranging from 0.1 mg CLA/g fat (coconut oil) to 0.7 mg CLA/g fat (safflower oil). Processed, canned, and infant foods were comparable in CLA content to similar unprocessed foods. Values for foods that contained beef, lamb, and veal were generally high in CLA. However the c-9,t-11 CLA isomer, believed to be the biologically active form, tended to be lower in cooked meats. In animal and dairy products the c-9,t-11 CLA isomer accounted for 75 and 90%, respectively, of the total CLA; in plant oils less than 50% of the total CLA was the c-9,t-1 I CLA isomer. The results show that considerable differences occur in the CLA content of common foods and indicate the possibility of large variations in dietary intakes of CLA.
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Ribeye steaks (Longissimus muscle) and ground beef from 15 Angus or Angus × Hereford steers slaughtered at weights of 480–500 kg were evaluated for proximate composition, color, β-carotene content and consumer preference. Three groups of five animals were finished on annual ryegrass pasture (Lolium multiflorum), ryegrass and ‘Coastal’ bermu-dagrass hay (Cynodon hybrid), or a feedlot diet.β-carotene content of ribeye steaks and ground beef was higher (p < 0.05) for the forage finished animals than those finished in the feedlot. There was no difference in scores from consumer panels (n = 80) for steaks from feedlot or pasture finished animals, but scores for ground beef from cattle finished on the feedlot diet were higher than other treatments (p < 0.05).