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Pale soft exudative (PSE) and dark firm dry (DFD) meats: Causes and measures to reduce these incidences—A mini review

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Pale Soft Exudative (PSE) and Dark Firm Dry (DFD) meats are two of the major quality defects facing the meat industry. These defects reduce consumer acceptability, shelf life and yield of meat thus affecting profits tremendously. Breed, sex, species, pre-slaughter and post-slaughter handling of animals are among the main predisposing factors contributing to PSE and DFD in meats. Nowadays, strenuous efforts are being made by farmers, researchers and all stakeholders in the meat industry to reduce the incidence of PSE and DFD meats. Modern technologies to reduce these incidences in meats have included careful design of vehicles for transporting live animals to the abattoir, the design of abattoirs, stunning methods, and chilling processes. Various additives and/or ingredients have also been introduced to improve upon the processing qualities of PSE and DFD in processed meat products. In this review, PSE and DFD meats, the causes and measures to reduce these incidences are described.
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*Corresponding author.
Email: nrlhd@usm.my
Tel: +6046532112, Fax: +6046573678
International Food Research Journal 18: 11-20 (2011)
Adzitey, F. and *Nurul, H.
Fish and Meat Processing Laboratory, Food Technology Programme,
School of Industrial Technology, Universiti Sains Malaysia,
Minden, 11800, Pulau Pinang, Malaysia
Review Article
Pale soft exudative (PSE) and dark rm dry (DFD) meats:
causes and measures to reduce these incidences - a mini review
Abstract: Pale Soft Exudative (PSE) and Dark Firm Dry (DFD) meats are two of the major quality defects
facing the meat industry. These defects reduce consumer acceptability, shelf life and yield of meat thus affecting
prots tremendously. Breed, sex, species, pre-slaughter and post-slaughter handling of animals are among the
main predisposing factors contributing to PSE and DFD in meats. Nowadays, strenuous efforts are being made
by farmers, researchers and all stakeholders in the meat industry to reduce the incidence of PSE and DFD
meats. Modern technologies to reduce these incidences in meats have included careful design of vehicles for
transporting live animals to the abattoir, the design of abattoirs, stunning methods, and chilling processes.
Various additives and/or ingredients have also been introduced to improve upon the processing qualities of PSE
and DFD in processed meat products. In this review, PSE and DFD meats, the causes and measures to reduce
these incidences are described.
Keywords: pale soft exudative, dry rm dark, meat, meat industry
Introduction
Protability in any venture has model the meat
industry to aim towards producing animals that are
efcient feed converters, fast growing and have high
lean meat content with minimum production cost.
These have been achieved through manipulation of
genetic made up of animals and careful selection of
breeds. These have also resulted in the production
of animals that are much more susceptible to stress
and consequently the development of meat quality
defects such as Pale Soft Exudative (PSE) and Dark
Firm Dry (DFD) meats. Other quality defects such as
bloodspalsh bruising, skin blemish, poultry cyanosis,
two-toning, spoilage of meat, broken bones and
death (Calkins et al., 1980; Forrest, 2010) have been
identied. Earlier on, PSE was associated with pigs
and DFD in all species. However, PSE characteristic
meat has been reported in turkey (Owens et al., 2000),
chickens (Swatland, 2008), ostriches (Van Schalkwyk
et al., 2000) and cattle (Aalhus et al., 1998) in recent
times. This explains the degree to which PSE and
DFD in meats are evolving.
Quantity and quality determine the price
consumers are prepared to pay for meat and meat
products. As the live animal is converted to meat, and
the meat moves along the line of distribution (from
slaughter, processors, retailers and nally to the
consumer), quality becomes increasingly important
and the quality characteristics change (O’Neill et al.,
2003). PSE and DFD meats look unattractive and
discriminated against by consumers (Viljoena et al.,
2002). They have poor processing characteristics,
reduce yield and high potential of spoilage (Newton
and Gill, 1981) compared to normal meat. There
can also be the danger that consumers will begin
to associate poor quality meat to food safety issues
(Cassens, 2000).
The conditions of PSE and DFD meats are
signicant causes of nancial loss. Cassell et al.
(1991) showed that PSE and DFD meat cost the
Australian food industry $20 million. In UK, Guise
(1987) reported that, an annual cost of $20 million
was incurred by the pig industry due to PSE and DFD
meats. The normal rate of incidence for PSE and DFD
meats is reported to range from 10 to 30 % but in some
isolated cases may be up to 60 % (McKeith et al.,
1994, Santos et al., 1994). In the USA, the estimated
percentage of PSE and DFD in meat was reported
to be 16 % and 10 %, respectively (Cassens et al.,
1992). In Canada, Fortin (1989) reported an estimated
prevalence of PSE to be between 20 – 90 %. Santos
12 Adzitey, F. and Nurul, H.
International Food Research Journal 18: 11-20
et al. (1994) showed an estimated prevalence of 30 %
and 10 % for PSE and DFD respectively, in Portugal.
Surveys have suggested that there is an increasing
incidence of PSE and DFD in meat (Warriss, 2000).
This work aimed at explaining PSE and DFD meats,
the phenomenon that leads to PSE and DFD, and
possible suggestions to reduce these incidences.
What is PSE and DFD meat?
PSE and DFD meat conditions are described
in relation to the characteristics of normal meat.
Nowadays, it can be suggested that both conditions
occur in all species depending on how animals are
handled pre-slaughter. They are dened in connection
with the pH of meat at a specic time after slaughter.
PSE is said to have occurred when the pH of meat is
< 6 at 45 minutes after slaughter. DFD (also known
as dark cutting in beef) is when the ultimate pH post
mortem measured after 12 – 48 hours is ≥ 6. Table 1
shows typical PSE, normal and DFD meats. Table 2
summarizes typical pH value limits for PSE, normal
and DFD. In practice, allowances can be allowed
for these pH ranges. For example in countries where
the incidence of PSE is high a stricter pH value of <
5.8 post mortem at 45 minutes can be used (Warriss,
2000). Similarly, an ultimate pH value of 6.2 can be
allowed for DFD meat depending on the species. The
above denitions do not also take into account the
variation in different muscles of the carcass, therefore
minor considerations have to be made in judging
meat as being PSE or DFD. Warriss (2000) said that
for redder muscles especially those found around the
neck and shoulder regions, a much higher pH value
of < 6.3 can be considered normal. Red, oxidative
muscle bres have relatively low concentration of
glycogen which can easily be depleted post mortem.
This makes them prone to DFD. Example is the
muscles in the ham region. Conversely, white muscle
bres have relatively high glycogen and are prone to
PSE. Example is the muscles in the loin region.
The determination of PSE, normal or DFD is also
achieved subjectively or objectively by measuring
meat color, pH and drip loss. Table 3 shows the color
and drip loss values for various categories of PSE and
DFD meats.
Causes of PSE and DFD
The most common factor leading to both PSE and
DFD in meat is stress ante-mortem. Exposing animals
to acute stress just before slaughtering leads to PSE.
Acute or short term stress that can lead to PSE include
the use of electric goads, ghting among animal just
before sticking, beating of animals prior to slaughter
and overcrowding in the lairage. Acidication occurs
in muscles post-mortem due to the breakdown of
glycogen to lactic acid. In PSE meats, the rate of
acidication after slaughter is stimulated faster than
normal and lower pH values are reached in the muscle
when the temperature of the carcass is still high. The
combination of low pH and high temperature in PSE
meat causes the denaturation of some muscle proteins
leading to reduction in their water holding capacity.
This happens because the myobrillar components
(the myolament lattice) expel the resulting uid into
the extracellular space which increases in volume
(Warriss 2000). When such meat is cut the uid is
released resulting in the exudates. A large amount
of exudates reects poor water holding capacity as
found in PSE meats. Warriss (2000) explained that,
light scattering from meat surface is probably due to
differences in refractive indices of the sarcoplasm
and myobrils. The larger the difference, the higher
the scattering and the paler the meat appears. The
shrinkage of the myolament lattice increases the
amount of light reected from the meat. At high
scattering the amount of absorbed light is low and
the haem pigments selectively absorbed green light,
thus reducing the normal red color. This makes PSE
meat less red and more yellow. The low pH in PSE
also promotes the oxidation of haem pigments from
purple or red myoglobin (Mb) and oxymyoglobin
(MbO2) to brown metmyoglobin (met Mb).
When animals are exposed to chronic or long
term stress before slaughtering DFD meats can occur.
Examples of chronic stress are transportation animals
over long distances, long hours of food deprivation,
and overcrowding of animals in the lairage over a
long period of time. Chronic stress prior to slaughter
leads to the depletion of stored glycogen, thus less
glycogen is available post-mortem affecting the
normal process of acidication and leaving the pH of
meat high. A condition referred to as DFD. In DFD,
Warriss (2000) explained that, the high pH results
in relatively little denaturation of proteins, water is
tightly bound and little or no exudates is formed.
This is because there is little or no shrinkage of the
myolament lattice and the differences in refractive
index of the myobrils and sarcoplasm are reduced.
The muscles absorbed light making the meat appear
darker. Oxygen penetration is reduced by the closed
structure and any oxygen reaching the interior is used
up by the high cytochrome activity encouraged by
the high pH. This results in a thin surface layer of
bright red oxygenated myoglobin (MbO2) allowing
the purple color of the underlying reduced myoglobin
(Mb) to show through. Table 4 and 5 summarize the
events leading to PSE and DFD in meats.
Pale soft exudative (PSE) and dark rm dry (DFD) meats: causes and measures to reduce these incidences 13
International Food Research Journal 18: 11-20
Typical Actual Condition
PSE meats
Normal meats
DFD meats
Table 1. Actual condition of different typical meats
14 Adzitey, F. and Nurul, H.
International Food Research Journal 18: 11-20
No. Condition Main conditions describing them References
1. PSE Meats with pH at 45 minutes being
lower than 6.0
Warriss (2000), Barbut et al. (2005), Swatland
(2008)
Meats with pH ultimate value of 5.3
Warriss (2000), Barbut et al. (2005) Swatland
(2008)
2. Normal Meats with pH at 45 min being 6.4 Warriss (2000), Viljoena et al. (2002)
Meats with pH ultimate value of 5.5
Warriss (2000), O’Neill et al. (2003), Gua`rdia
et al. (2005)
3. DFD Meats with pH at 45 minutes being 6.4 Warriss (2000), Viljoena et al. (2002)
Meats with pH ultimate value higher
than 6.0
Bartos et al. (1993), Kreikemeier et al. (1998),
Mounier et al. (2006)
Table 2. Typical limits of pH values for PSE, normal and DFD meat.
No. Meat
type
DFD Normal PSE Reference
1. Lightness (L*) Pork 42 - 48 54 60 - 66 Warriss and Brown (1993)
Beef 37 - 40.4 - - Muchenje et al. (2009)
Turkey - 47.31-48.99 54.72 -56.85 Owens et al. (2000)
Pork 45.6 - - O’Neill et al. (2003)
2. Hue (o) Pork 1-22 38 48 -53 Warriss and Brown (1993)
Pork 7.8 - - O’Neill et al. (2003)
3. Saturation Pork 3 - 5 79 - 12 Warriss and Brown (1993)
(chroma) Pork 6 - - O’Neill et al. (2003)
4. Reectance Pork 20 - 32 44 56 - 67 Warriss and Brown (1993)
(EEL)
5. Drip loss (%) Pork 0 - 5 10 13 - 15 Warriss and Brown (1993)
Turkey -0.72 2.52 Owens et al. (2000)
6. Colour Beef 4.8 ±1.6 6.1 ±1.9 -Viljoena et al. (2002)
Table 3. Color and drip loss values in meat of different quality
Pale soft exudative (PSE) and dark rm dry (DFD) meats: causes and measures to reduce these incidences 15
International Food Research Journal 18: 11-20
No. PSE-Meat References
1. Short term stress prior to slaughter Warriss (2000)
2. Accelerated rate of post-mortem glyclolysis
resulting in low pH while carcass is still high
Bowker et al. (2000)
3. Pale, lean and soft texture
Santos et al. (1994),
Bowker et al. (2000)
4. Elevated muscle glycogen content and an extended duration of post-
mortem glycolysis
Bowker et al. (2000)
5. Protein denatures
Santos et al. (1994), Bowker et
al. (2000)
6. Large extracellular space Warriss (2000)
7. Low water binding capacity
Santos et al. (1994), Bowker et
al. (2000)
8. It scatters more light back to the observer
Swatland (1993), Swatland
(2008)
9. Reduction in absorption of green light by Mb Warriss (2000)
10. Meat looks less red Warriss (2000)
Table 4. Summary of events leading to PSE in meats
No. DFD-Meat Reference
1. Long term stress prior to slaughter Warriss (2000)
2. Pre-slaughter glycogen depletion in muscle
resulting in meat with a higher ultimate pH
Viljoen et al. (2002), Kannan
et al. (2002)
3. Small extracellular space Warriss (2000)
4. High water holding capacity
Zhang et al. (2005),
Apple et al. (2006)
5. Amino acids are utilised due to glucose depletion and spoilage becomes
evident at lower cell densities than in normal meat
Newton and Gill (1981),
Gardner et al. (2000)
6. Spoilage odour is produced at an early age
Newton and Gill (1981),
Gallo et al. (2003)
7. High variation in tenderness Silva et al. (1999)
8. Meats transmit more light into its depth Swatland (2008)
9. Dark in colour Mounier et al. (2006)
10. O2 used up by high cytochrome activity Warriss (2000)
11. Meat looks less red Warriss (2000)
Table 5. Summary of events leading to DFD in meats
16 Adzitey, F. and Nurul, H.
International Food Research Journal 18: 11-20
Preventive measures to reduce the incidence of PSE
and DFD in meats
The prevention of PSE and DFD in meats will
rely mainly on measures to avoid stress in animals
prior to slaughter. These stresses include removal
from their home environment, loading and unloading
onto vehicles, feed and water deprivation during
transportation, holding in unfamiliar surroundings,
mixing with strange animals, lousy odour, high
temperature and noise produced by moving vehicles
(Warriss, 2000).
First of all there is the need to develop breeds that
are resistance to stress. This is because the incidence
of PSE and DFD has been found to be high in stress
susceptible animals by many authors (Warriss, 2000).
Barton-Gade (1988) reported that the occurrence of
PSE meat is undoubtedly related to certain genotypes
that are stress susceptible (Halothane positive) and
have lean meat. Muchenje et al. (2009) found that
Bonsmara steers suffered the most pre-slaughter
stress compared to Angus and Nguni breeds when
they were all exposed to the same condition of pre-
slaughter handling. Inversely, Koch (2004) found
that Bonsmara breeds had the lowest levels of stress
hormones in a study comparing several Bos taurus
and Bos indicus breeds. Animals’ reactions to stress
are governed by a complex interaction of genetic
factors and previous experiences (Mormède et al.,
2002; Mounier et al., 2006). Nevertheless, tropical
breeds in particular are resistance to stress but have
poor growth rate. Temperate breeds on the other hand
are more susceptible to stress but have good growth
rate. A combination of genotypes from both temperate
and tropical regions could be useful in reducing the
incidence of PSE and DFD meats.
It has also been showed that females and
castrates have higher probability of producing DFD
compared to entire males (Gua`rdia et al., 2005).
On the contrarily (Warriss, 1996) reported that
entire males are more aggressive than castrates or
gilts and this behavior in boars cause a high level
of hostile confrontations and ghts among them,
and subsequently prone to producing PSE and DFD
meats. Van der Wal et al. (1999) observed that in the
absence of additional stress there were no differences
between sexes but as soon as stress stimuli were
introduced males were more resistant. Entire males
show a faster rate of recuperation from stress due to
their more aggressive sexual behaviour, making them
more used to chronic stress. This probably suggests
that if males are handled well prior to slaughter they
will produce less DFD and PSE meats, and therefore
more males could be bred for meat purposes.
Loading of animals onto trucks for transportation
to the abattoir has to be done with minimum stress.
As much as possible loading should be done in a
quiet atmosphere, avoiding the use of sticks and
other forms of force. Avoid chasing and running
after animals to direct them into their transporting
vehicles. Climbing ramps that slope gently should be
used for loading animals unto trucks for transport. In
chickens, the use of mechanical harvesters (instead of
manual harvesting by a team of farm hands) equipped
with rotating rubber ngers have been suggested
by Berry et al. (1990). The rotating rubber ngers
collects and encourage the birds to move onto a
moving conveyer thus reducing stress. When manual
harvesting is being practiced, the team should be
trained on proper ways of handling animals. Animals
should be unloaded immediately when they arrive
at the slaughter house. Unloading of animals at the
abattoir should also be done in a quiet and gentle
manner. Unloading platforms should be lowered to
the ground level to facilitate descending. Wide gaps
should not be created between the vehicle and the
landing ground to prevent the animals from jumping.
The use of hydraulic lifts in some vehicles for some
animals is helpful to reduce stress.
Animals are transported to the market for sale
or directly from the farm to the abattoir. In either
cases stress must be reduced to the minimum. Keep
transportation and marketing times short. This
implies that farms, markets and abattoirs should be
situated close to each other. Vehicles for transporting
animals must provide them with enough ventilation
and should be well maintained. Provide shade, water
and feed for the animals (especially if the animals
will keep long in the market). In general it is accepted
that on farm feed withdrawal from 12 to 18 h before
transport is a good practice for preparing pigs for
transportation (Guise, 1990). To avoid long marketing
times, Warriss (2000) suggested a computer auction
marketing system where the characteristics of the
animals are display on the internet for interested
buyers to make orders. Such a system will reduce
marketing time and the stress involved in holding
animals for long hours in the market. Keep animals in
their rearing group as mixing of unfamiliar animals
will trigger ght. Overcrowding should be avoided as
it increases the incidence of PSE and DFD in meats
due to stress (Gua`rdia et al., 2005).
Animals waiting for slaughter can be stressed by
factors such as restraint, handling, novelty of the pre-
slaughter environment, adverse weather conditions,
hunger, thirst and fatigue (Muchenje et al., 2009).
At the abattoir animals should be rested enough
to recover from stress before slaughtering. Sugar
or molassed feeding has been shown to replenish
Pale soft exudative (PSE) and dark rm dry (DFD) meats: causes and measures to reduce these incidences 17
International Food Research Journal 18: 11-20
muscle glycogen levels thus helping to prevent DFD
(Warriss, 2000). Provide animals with food and water
if they will spend more time in the lairage although
this must be avoided. Provide beddings or straw on
the oor if the animals will keep longer than expected
in the lairage. Animals can be sprayed with mist water
to cool them down especially when the weather is
hot. Lairage time should also be kept short. Malmfors
(1982) showed that both long journeys and long
lairage periods cause a signicant increase in the risk
of PSE and DFD meats. Nanni Costa et al. (2002)
also found that lairage time was the most important
pre-slaughter factor contributing to DFD meats
among the factors they investigated. Grandin (1998)
recommended a resting period of between 2 – 4 hour
in the lairage prior to stunning and/or sticking.
The slaughtering process is a critical point that can
lead to PSE meat if any stress is introduce at this level.
Abattoirs must be well designed to ensure that the
animals are exposed to the least stress prior to slaughter.
Stunning methods such as the use of mechanical
instruments (captive bolt pistol, percussion stunner
or free bullet), electrical stunning and anesthetic gas
(CO2) render animals unconscious prior to sticking.
This has the potential of reducing pain, distress and
struggling after sticking if well done and thus can
help reduce the incidence of PSE. Animals must be
well restrained before stunning and/or sticking to
reduce distress. Schaefer et al. (1992) showed that
pre-slaughter administration of electrolytes in cattle
and the use of sodium bicarbononate in pigs partially
alleviate metabolic acidosis and reduce the rate of
post-mortem glycolysis in muscles.
Carcasses are normally chilled after dressing.
Different cooling rates can affect the rate of pH fall
through lactic acid production, and the onset of rigor
mortis. This can have negative effect on the carcass
and meat quality. Modern chilling practice has focus
on speeding up the process of chilling by utilizing
refrigerated air in order to reduce microbial growth
and evaporative weight loss. There is evidence
that rapid chilling can reduce weight loss, the
manifestation of PSE, improve the water holding
and lean meat color (Warriss, 2000). Rapid chilling
can be achieved by reducing the size of carcasses,
covering of fats and effective circulation of cold air
over the meat surface.
Conclusion
PSE and DFD meats are discriminated against
by consumers. They have poor processing qualities
and cause huge nancial loss to the meat industry.
Stress is a major contributing factor to PSE and
DFD in meats. Stress arises from poor pre-slaughter
handling such as striking animals with sticks, kicking
them with the feet, forcing animals to move into the
transporting vehicle, starving, overstocking during
transport, and pushing animals to move in races at the
lairage. When handling animals prior to slaughter,
consideration should be made in terms of the kind
of species, breed, and age. In addition slaughtering
procedures and processing techniques should be
closely monitored to help reduce the incidence of
PSE and DFD in meats.
Acknowledgments
The rst author is grateful to the Institute of
Postgraduate Studies, Universti Sains Malaysia for
the opportunity given him to pursue a PhD programme
through USM Fellowship Scheme. Both authors are
grateful for the support given by the Universti Sains
Malaysia for running research in the area of meat
quality and processing.
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... There are several factors enhancing the pH values of meats post slaughter, one of which is the depletion of stored glycogen in the muscle of broilers. The less glycogen available post-mortem may affect the normal acidification process (postmortem anaerobic glycolysis) and thereby leaving the pH of meat high (Adzitey and Nurul, 2011). When compared to meats from broilers maintained at a normal density, the long-term stress due to high stocking density condition may be related to reduced muscle glycogen storage, resulting in higher pH values of meats post-mortem. ...
... According to Mir et al. (2017), meats with a pH greater than 6.0 experienced less protein denaturation. However, meats with pH levels greater than 6.0 are more likely to develop dark firm dry (DFD) meats (Adzitey and Nurul, 2011), which may reduce customer acceptance. In general, there is a positive link between broiler meat pH and WHC, with greater pH corresponding to increased WHC (Mir et al., 2017). ...
... In this study, however, the higher pH values of meats from high-stocked broilers treated with acidified turmeric were accompanied with decreased WHC of the corresponding meats. The lowering of WHC in meats has been linked to the post-mortem denaturation of muscle protein (Adzitey and Nurul, 2011). Given that higher pH levels are associated with less denaturation of muscle protein, the lower WHC of meats obtained from highstocked broilers treated with acidified turmeric appeared to be incongruent. ...
... Pale soft exudative meat (PSE) is among the best-known hereditary pork defects (Adzitey & Nurul, 2011;Barbut et al., 2008). PSE is associated with a mutated calcium channel (ryanodine receptor) and a higher susceptibility to acute stress before slaughter (Trevisan & Brum, 2020). ...
... Mapping of common pork defects usually relies on pH, colour, and drip loss measurements (Garrido, Pedauye, Banon, & Laencina, 1994). Typically, changes among these variables are found to be correlated, pointing to underlying physiological links (Adzitey & Nurul, 2011). The reduced water holding capacity is thought to be mainly caused by myofibrillar protein degradation, which in turn is affected by low pH, ionic strength, and oxidation of proteins (Huff-Lonergan & Lonergan, 2005). ...
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During post-mortem conversion from muscle to meat, diverse quality anomalies can emerge. Recent pork defects are often accompanied by deteriorating fibre structure. Here we investigate how bioimpedance response, an indicator of structural disintegration, can help in detecting quality defects. We, first, measured the relationship between standard meat quality variables (pHu, CIELAB, drip loss) and bioimpedance (BI) response. To screen for defect-biomarkers that are linked to aberrant bioimpedance and physicochemical indicators of quality decline, we performed LC-MS/MS proteomic analysis on samples, classified with a multivariate-based separation into good versus poor quality. We found that BI correlated significantly with, e.g., colour and drip loss. Proteomics revealed eleven proteins to be unique for either, good or poor ham quality groups, and maybe linked to structural degradation. In all, our data supports a wider integration of BI testing in pork quality testing to assess structural disintegration, which can render ham unsuitable for, e.g., costly curing.
... In beef, pH24 values are considered normal in the range of 5.4 to 5.8 [4], and pH24 ≥ 6.0 has been considered the main indicator of DFD meats [5]. However, depending on the species and the different muscles of the carcass, even higher pH24 values (over 6.2) should be considered [6]. Therefore, pH is not always a sufficiently reliable indicator to clearly identify DFD meat [7], and other aspects related to meat quality should be considered. ...
... In the RE breed, 38 samples were considered as normal and 4 as DFD meat (9.5%). These results are in agreement with previous studies [6] reporting an incidence of around 10% of beef production in Australia and the United Kingdom, although some studies including calves showed DFD percentages of up to 43%, considering pH24 ≥ 5.8 [25]. ...
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The potential of near-infrared reflectance spectroscopy (NIRS) to discriminate Normal and DFD (dark, firm, and dry) beef and predict quality traits in 129 Longissimus thoracis (LT) samples from three Spanish purebreeds, Asturiana de los Valles (AV; n = 50), Rubia Gallega (RG; n = 37), and Retinta (RE; n = 42) was assessed. The results obtained by partial least squares-discriminant analysis (PLS-DA) indicated successful discrimination between Normal and DFD samples of meat from AV and RG (with sensitivity over 93% for both and specificity of 100 and 72%, respectively), while RE and total sample sets showed poorer results. Soft independent modelling of class analogies (SIMCA) showed 100% sensitivity for DFD meat in total, AV, RG, and RE sample sets and over 90% specificity for AV, RG, and RE, while it was very low for the total sample set (19.8%). NIRS quantitative models by partial least squares regression (PLSR) allowed reliable prediction of color parameters (CIE L*, a*, b*, hue, chroma). Results from qualitative and quantitative assays are interesting in terms of early decision making in the meat production chain to avoid economic losses and food waste.
... Cuando los animales están expuestos a estrés crónico o a largo plazo antes del sacrificio, pueden ocurrir carnes DFD, como puede ser de estrés crónico debido al transporte de animales a largas distancias, largas horas de privación de alimentos y el hacinamiento de animales en el establo durante un largo período de tiempo; este estrés crónico antes del sacrificio conduce al agotamiento del glucógeno almacenado, por lo que hay menos glucógeno disponible post-mortem, lo que afecta el proceso normal de acidificación y deja alto el pH de la carne (Adzitey et al., 2012). El animal (carne de lidia, bovinos, ovinos o caprinos) llega cansado al sacrificio tras realizar un ejercicio intenso en el que se ha agotado el glucógeno muscular, la glucólisis anaerobia finaliza antes de alcanzar el pH final debido a que no hay sustrato, quedando el pH muscular por encima de 5.6, este es el caso se producen carnes DFD (oscura, firme y dura) que se caracterizan por tener una alta capacidad de retención de agua y un pH elevado que favorece la proliferación microbiana. ...
... Las condiciones de la carne PSE y DFD se describen en relación con las características de la carne normal, por lo que hoy en día, se puede sugerir que ambas condiciones ocurren en todas las especies dependiendo de cómo se manejen los animales. Se definen en relación con el pH de la carne en un momento específico después del sacrificio, se dice que el PSE se produce cuando el pH de la carne es < 6 a los 45 minutos del sacrificio y en DFD (también conocido como corte oscuro en carne de res) es cuando el pH post mortem final medido después de 12 -48 horas es 6. La tabla 4 muestra las carnes típicas PSE, normales y DFD (Adzitey et al., 2012). ...
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El bienestar animal (BA) se ha convertido en un importante atributo en el concepto de calidad sensorial y ética de los alimentos de origen animal, y un tema de interés en el comercio internacional de la carne. La calidad de la carne posee características principales que determinan la calidad como son las propiedades fisicoquímicas, organolépticas y microbiológicas. Estas características están influenciadas por factores como son sistema de producción, alimentación y manejo pre-mortem de los animales y manejo post-mortem de la carne. El manejo pre-mortem es muy importante, donde la fisiología del estrés, y los factores que la causan (ayuno, transporte, espera, aturdimiento y especie) y el efecto que tiene cada etapa del manejo pre-mortem, se ve reflejado en la calidad de la carne obtenida (pH, conductividad, color, capacidad de retención de agua y vida de anaquel). Durante el transporte, cargue y descargue los bovinos son sometidos a factores estresantes que afectan su bienestar y la calidad de la carne, además de producir importantes pérdidas económicas a los productores.
... To increase marginal benefts, mixing animals of diferent ages, sexes, and novelty during transport might cause high numbers of animals to be stressed and killed by restraint [6,12]. Tis chronic stress before slaughter leads to the depletion of stored glycogen, which results in dark and frm dry meat [41,49]. Outlining guidelines of legal support, design of appropriate vehicles for use in transporting animals, and creating awareness on engaging in animal welfare are needed in a holistic approach for the trader. ...
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Perception is the knowledge of an individual/group gained from experience and impressions of the ideal situation. Ethiopian livestock marketing has a different stage and large actors. However, in the flow chain, there is less communication. Because they only perceive for their benefit rather than care for a quality product. This happened because the production mapping was not understood among them. The majority of producers fetch too old animals after being culled from production and those that might be abnormal due to disease and chronic stress. Traders transport mixed animals through nondedicated vehicles and long trekking without feeding and watering. Abattoir men worked with poor facilities. They perceived that the time stay animals in Lairage, breeding, bleeding, and carcass handling is the major problem in meat quality in Ethiopia. The slaughtering has been conducted in brutal ways of stunning using either a hammer or knife at the atlanto-occipital space of the animal on the floor side by side. The majority of butchers in Ethiopia are located on the main road for their products to be easily displayed to clients, and they hang meat on the open shelf without packing, which exposes the product to aerobic spoilage by bacteria and yeasts. Traders/brokers are promoting the product based on the commission they earn rather than the quality and health of the animals. However, as a principle, each actor has a responsibility to manage risk as they benefit socially and economically from firms. Government entities should play an important role in shaping actors’ perceptions and understanding of biosecurity measures. Mainly, the interventions should focus on improving business models and technological adoption. This model is used for improving vertical relationships among operational actors, horizontal relationships with logistics providers, and market promotion measures to attract foreign direct investors and importers, transforming traditional practices of animal husbandry into commercial ones. Because a key activity for each value chain actor is availing of the final product safely at the right place and time. The review was designed to convey information to enhance the linkage between meat value chain actors and optimize management skills in Ethiopia.
... Animales expuestos a un estrés severo en corto tiempo ante mortem, presenta un descenso rápido del pH post mortem entre 5.3 y 5.7 los que es característico de una carne PSE, que se defina con una desnaturalización de proteínas, causando una mayor pérdida de agua y un color rojo pálido, por el contrario animales sometidos a un estrés prolongado o exceso de ayuno ante mortem, el pH será de un 6.4 a 6.8, debido a la poca formación de ácido láctico, que es característico de una carne DFD afectando el color, textura, capacidad de retención de agua y perdida por goteo de la carne. Estos dos tipos de carnes son menos aceptables por los consumidores (Adzitey & Nurul, 2011;Romero & Sánchez, 2012). ...
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The central objective of the 2020 handbook was to enrich the scientific literature on the topics of sustainability, tourism and education at a world level with full adherence to the bibliography available in various digital databases or printed texts from where relevant information concerning basic research and applied on the topics of the handbook. The method used was multimodal since it was resorted to desk work based on quantitative techniques and field work where qualitative techniques such as participant observation and the application of questionnaires were applied. Among the results found were: a) regardless of the exploitation in the productive systems, the existence of economic, ecological, social and political conditions is significant, which allow it to flow harmoniously in time and space; b) sustainable tourism contributes to the people of the world to promote activities that contribute to the use of the natural and cultural landscape in a sustainable way and c) education with an environmental perspective is currently essential for the achievement of human talents to have a respectful vision on natural heritage, biological diversity and the resolution of contextual problems. Among other conclusions, the following were obtained: i) in the productive systems the exposition of the basic concepts of the quality of meat and its physical-chemical classification, its nutritional importance and human consumption are essentialfor human growth and development; ii) sustainable production in dairy cows is vital for hormonal manipulation of the reproductive cycle; iii) co-processing in the cement industry represents a source of ecological competitive advantage, where the generation of value of these organizations for society is greater than the final price of their products to their customers; iv) tourism is an important economic activity in any country in the world; v) Mexican beaches are suitable for intensive tourist recreation, sincevisitors have observed transparent waters, fine-textured sand and an optimal climate of 26°C; seawater shows minimal concentrations of enterococci thanks to the cleaning actions carried out by local entrepreneurs dedicated to tourism and vi) the ideal instances for teaching environmental education, sustainability and tourism are the institutions of higher education linked to the government and socialsector.
... The generation of drip during ageing/storage could have impacts on meat quality in several ways. Firstly, excessive drip can reduce meat functionality and quality, which is commonly rejected by consumers [49]. As drip generally contains mainly water-soluble protein fractions including enzymes, proteins, peptides, amino acids and nucleotides, increased drip loss could also impact the nutritive value of meat [50]. ...
Article
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Active packaging (AP) has been developed to improve the safety, quality and integrity of food, and minimise food waste, while its application in meat is scarce. This review aims to describe meat production and consumption culture in China and New Zealand to provide the context for packaging innovation requirements, focusing on the emerging opportunities for AP to be used for the improvement of the shelf-life of pre-rigor, aged, and frozen-thawed meat products. Sustainable polymers utilised in the manufacturing of AP, manufacturing techniques, the release mechanisms of actives, and legal and regulatory constraints are also discussed. Diverse market compositions and consumption cultures in China and New Zealand require different packaging solutions to extend the shelf-life of meat. AP containing antimicrobials, moisture regulating agents, and an-tioxidants may be used for pre-rigor, dry- and wet-aged products and in improving the quality and shelf-life of frozen-thawed meat. Further innovations using sustainably produced polymers for AP, along with incorporating active compounds of multiple functions for effectively improving meat quality and shelf-life are necessary. Challenges remain to resolve issues with scaling the technology to commercially relevant volumes as well as complying with the rigorous legal and regulatory constraints in various countries.
Article
The study investigated the effect of a mixture of germinated papaya seed flour and chitosan (GPS-CH) in comparison to the germinated papaya seed flour (GPS) alone on growth, blood profile, intestinal indices and meat quality of broilers. A total of 288 14-day old Cobb chicks were divided into three groups with 8 replications, including CONT (chicks receiving basal feed with no additive), GPS (chicks receiving basal feed supplemented with 0.5% GPS), and GPS-CH (chicks receiving basal feed supplemented with 0.5% GPS and 0.2% chitosan). Treatments had no effect (p > 0.05) on broiler growth. Spleen was lower (p < 0.05) in GPS and GPS-CH than in CONT. Thrombocytes were lower (p < 0.05) in GPS and GPS-CH than in CONT. Total triglyceride and protein were higher (p < 0.05) in GPS and GPS-CH than in CONT. Jejunal villi height (VH) and ileal VH to crypt depth ratio of GPS-CH were higher (p < 0.05) than that of CONT and GPS birds. Total fat in breast meat was lower (p < 0.05) in GPS-CH than in CONT and GPS. The highest (p < 0.05) pH was found in GPS-CH breast. The yellowness values were lower (p < 0.05) in GPS-CH than in CONT and GPS breast. GPS thigh had lowest (p < 0.05) moisture and highest (p < 0.05) fat. Ash was higher (p < 0.05) in GPS-CH than in CONT thigh. Water holding capacity (WHC) was higher (p < 0.05) in GPS-CH than in CONT and GPS thigh meats. Cooking loss was lower (p < 0.05) in GPS-CH than in GPS thigh meats. Compared to GPS, the pH values of thigh meats were higher (p < 0.05) in GPS-CH and CONT meats. The yellowness values were lower in GPS and GPS-CH than in CONT thigh. In conclusion, GPS-CH was beneficial in improving immune responses, nutrient bioavailability, intestinal morphology and meat quality of broilers during the grower period.
Chapter
Meat forms an essential part of the non-vegetarian diet and is liked for its unique taste. It is a rich source of nutrients, providing good quality animal proteins, essential amino acids and fatty acids, minerals, trace elements and vitamins particularly B-complex. The muscle tissue constitutes the major part of the carcass of meat animals which is considered as food. Muscle fibres are the basic units of both the living muscle and of meat. The conversion of muscle to meat is a very complex process. This process is known to affect the meat qualities like colour and flavour which are dependent on the oxidative changes occurring in meat. This chapter deals with the composition of meat, its structure and conversion of muscle to meat, physical and chemical characteristics and the chemistry of spoilage. The chapter concludes with a description of chemical changes occurring in meat as a result of different processing and preservation techniques.
Chapter
The bright cherry-red color of retail fresh meat is a major quality influencing the consumers' purchase decisions at the point of sale. Numerous endogenous and exogenous factors influence the redox biochemistry of myoglobin in postmortem skeletal muscles and fresh meat color. Current research indicates that the interinfluential interactions between myoglobin, mitochondria, and biomolecules govern meat color stability in muscle-, species-, and packaging-specific manner. Advances in bioanalytical techniques enable characterizing the fundamental mechanisms of these biomolecular interactions, which in turn are exploited to develop innovative pre- and postharvest strategies to improve fresh meat color stability.
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Pale, soft, and exudative (PSE) pork is primarily caused by an accelerated rate of postmortem glycolysis resulting in low muscle pH while carcass temperature remains high, thus causing protein denaturation. Numerous factors influence the rate of postmortem metabolism and may be responsible for the rapid pH decline characteristic of PSE pork during the 1st h postmortem. Release of high levels of Ca 2+ from the sarcoplasmic reticulum into the sarcoplasm triggers an accelerated rate of postmortem glycolysis and is responsible for the high incidence of PSE observed in halothane pigs. Because total muscle ATPase activity is closely associated with rate of glycolysis, differences in myosin ATPase activity may explain in part the accelerated glycolysis in PSE development. Although important in determining the overall rate of glycolysis, differences in glycolytic enzyme activities have failed to explain discrepancies in postmortem metabolism between PSE and normal muscle. Elevated muscle glycogen content and an extended duration of postmortem glycolysis can also result in PSE-like characteristics, as seen in RN - pigs. Shifts in muscle fiber type toward higher proportions of glycolytic fibers may help explain the incidence of PSE. Inherent differences in mATPase activity, Ca2+ regulation, glycolytic enzyme profiles, and glycogen content between muscle fiber types integrate vari- ous mechanisms responsible for the abnormal postmortem glycolysis in PSE muscle. In an effort to delineate potential mecha- nisms responsible for PSE, models to artificially induce PSE, such as retarding temperature decline and electrical stimulation, provide useful tools. The value and limitations of these models stem from their abilities to alter postmortem temperature and pH declines and to effectively simulate the protein denaturation typical of PSE pork.
Article
The condition of pale, soft and exudative (PSE) pork meat was recognized and documented by 1960, and the condition of porcine stress syndrome (PSS) was understood within the decade of the 1960s. The two are associated, with PSS animals having a high probability of producing PSE meat. Both are economically important with potential death losses, especially during transport, due to PSS, and PSE meat being viewed as of inferior quality by consumers and also having less value for further processing. An enormous amount of research has been directed at the problem and is presented in the manuscript as a time-line approaching a half-century of effort. Surveys of incidence showed, in pork produced in the USA, that 18% was PSE in 1963 and 16% was PSE in 1992. Fortunately, molecular/genetic understanding and tools are now available to attack the problem, but solving it may require further impetus — such as strong and unified resolution by producers, industry associations and governmental agencies.
Article
The aims of this study were to develop a muscle biopsy technique which imposed minimal stress on cattle, enabling accurate monitoring of muscle glycogen concentration; to develop a method based on exercise, for controlled depletion of glycogen from muscle; and to utilise the model to determine the ability of cattle on hay and cereal grain diets to replete muscle glycogen. Expt 1 established the influence of repetitive muscle biopsies on muscle glycogen concentration. It consisted of 3 trials in which cattle received 4 serial biopsies every 36 h over a 108-h period. Repetitive biopsy had minimal impact on M. semimembranosus (SM) glycogen concentrations, although it did reduce concentration in the M. semitendinosus (ST), particularly when animals were penned individually. Expt 2 established an exercise regimen in which cattle were trotted at 9 km/h for five 15-min intervals, with 15 min rest between each interval, depleting muscle glycogen by approximately 50%. Expt 3 determined the repletion rates of muscle glycogen, by utilising the exercise/biopsy model. Cattle were allocated to 4 dietary treatments: hay, silage, hay–barley, and hay–maize. The metabolisable energy (ME) of these rations ranged from 8 to 11.3 MJ/kg. After the exercise regimen, glycogen concentration repleted in a linear fashion over 72 h in the SM of the animals fed maize, barley, and silage. In contrast, the ST of these animals was refractory to glycogen repletion over the same period. Both the SM and ST of the cattle on the hay diet showed no significant repletion following exercise. Repletion following exercise demonstrated a positive linear relationship with ME intake.
Article
Whilst improvements have been made over the last 15 years in the collection and transport of live broilers, a satisfactory mechanized system for harvesting birds has yet to be fully accepted by the industry. AFRC Engineering have investigated the mechanical harvesting of broilers, with the objectives of making the task of catching more acceptable to all concerned, reducing injury to the birds and improving animal welfare. A brief background to the nature of the broiler handling operation is presented. The limitations imposed by the design of existing houses and the behaviour of live broilers are discussed in the light of attempts to mechanize the handling operation. The development of machines based on a patented poultry harvesting assembly is followed from the initial concept of a two-rotor pick-up head to the final three-rotor sweeping head. The findings from trials on commercial sites are shown which indicate that the machine is capable of working at the required catching rate of 6000 birds/h, whilst being less stressful than conventional hand catching methods.
Article
To determine the efficacy of electrolyte supplementation in normalizing animal physiology following transport, 89 yearling beef bulls averaging 495 ± 13 kg were allocated to one of four lairage treatment groups of 0, 12, 24, or 36 h. Except for the 0-h group, all animals were given a 4-h road transport followed by 12, 24 or 36 h in lairage preslaughter without feed or water. Half of the animals in each time treatment were given free access to an electrolyte drink lairage. Transportation, handling and time off feed and water during lairage resulted in progressive increases in serum chloride ion concentration (P = 0.03) and for, the 36-h group, an increase in blood lactate levels (P = 0.02). Also, depletion of chloride in muscle (P = 0.007) and an increase in urinary sodium concentration (P = 0.0001) and osmolality (P = 0.0001) were seen in the 12-, 24- and 36-h groups. Neutrophile: lymphocyte ratios were observed to initially rise above (12-h group, P = 0.01) and then fall below (24- and 36-h groups, P = 0.01) control values. Combined fluid and electrolyte therapy post-transport assisted in normalizing many of these parameters, especially urine osmolalities. Live animal weight loss for electrolyte treated bulls was on average 1.5% less and resulted in an improved retention of cold carcass weight of between 2.2 kg (12-h group) and 7.6 kg (36-h group, P = 0.003).
Article
Beef and pork carcasses of normal quality were compared to those subjectively scored as PSE (pale, soft, exudative) postslaughter. Compared to normal meat, the PSE samples from both beef and pork exhibited a lower pH45 and glycogen content early postmortem while lactate concentration, L*, hue angle and chroma values were elevated (P<0.05). Drip loss for both PSE beef and pork was also higher than normal meat with a 2.8-fold increase for PSE beef and a 1.3-fold increase for PSE pork. Shear values for PSE beef were over 1 kg lower than control beef whereas shear values for PSE pork were over 1 kg higher compared to normal pork (P<0.05). It is clear from these data that rapid pH drops during early postmortem do not always result in similar changes in tenderness. A more complete understanding of the underlying cellular mechanisms of tenderization, electrical stimulation and the PSE condition should help to elucidate the paradox.
Article
A method for the prevention of dark-cutting in beef, based on recognition of social relationships within groups of bulls, was tested on 2234 bulls slaughtered under commercial conditions. When the influence of time between loading the animals and slaughter was eliminated statistically, the bulls of the socially stablized group showed the lowest pH(24) values, whereas those of the socially unstable group showed the highest ones. When the type of social group was eliminated statistically, the earlier slaughtered animals had lower pH(24) values than those slaughtered later. When the two major factors were integrated, there was no statistically significant difference in the pH(24) values in bulls of the socially stabilized group whether they were slaughtered immediately after transport or during the following day. In contrast, in bulls from the socially unstable group, the pH(24) values increased substantially after overnight lairage at the abattoir. In conclusion, for longer transportion, bulls from loose housing with stable social relationships should be used. It is necessary to keep the same social groups from loading to slaughter, strictly avoiding any mixing of strange bulls. Bulls from tethered stalls should be transported and slaughtered within as short a time after regrouping as possible.