Reduction of carcass yield in transported pigs

Pigs (53-70 kg) in a non-fasted state were either not transported or subjected to a journey lasting for 1 h or 6 h prior to slaughter. Pigs given the short transport lost 0.6% and pigs given the long transport 2.3% of their initial live weight. After lairage for 1 h with access to water, all pigs were killed 8 h after their last feed. Compared with pigs not transported before slaughter, killing out percentage was slightly, but not significantly, lowered in the short transport group and significantly (P<0.05) reduced in the long transport group. The loss in carcass weight of the latter group amounted to 2.1% of the carcass weight of the untransported control pigs. Overall, killing out percentage and liver weight expressed as a percentage of liveweight were negatively correlated with the percentage loss of live weight in transport (P<0.02). The carcass weight loss on chilling was not influenced by treatment. Measurements of adrenal ascorbic acid suggested that most of the stress of transport occurred during the loading and first hour of the journey. Transported pigs drank more water in lairage, particularly those transported for 6 h which also had a higher total protein concentration in their plasma (P<0.05). Plasma creatine phosphokinase activity was not influenced by transport. It is suggested that enforced deprivation of water is an important contributing factor to the weight loss of pigs during transport but that physical activity is not.     

Effect of gender and castration of females and slaughter weight on performance and carcass and meat quality of Iberian pigs reared under intensive management systems

A total of 360 Iberian dam × Duroc sire pigs was used to study the influence of gender and castration of females (CM, castrated males; CF, castrated females; IF, intact females) and slaughter weight (SW; 145 and 156 kg body weight, BW) on performance and carcass and meat quality. Each treatment was replicated four times (15 pigs). Intact females ate less, tended to have better feed conversion and had less carcass fat and more primal cuts yield than CM and CF. Pigs slaughtered at 156 kg BW ate more feed and had worse feed conversion than pigs slaughtered at 145 BW. An increase in SW improved carcass yield, but tended to decrease trimmed ham yield. Intact females are an alternative to castrated females for intensive production of Iberian pigs. Also, the reduction in slaughter weight from 156 to 145 kg BW is recommended for this type of production.     

The effect of handling pre-slaughter and carcass processing rate post-slaughter on pork quality

Forty-eight male crossbred (Large White—Landrace) pigs were used in a 2×2 factorial design to determine the effect of pre-slaughter handling (minimal and negative handling prior to slaughter) and the rate of carcass processing post-slaughter [normal rate (45 min) and delayed rate (70 min) from time of exsanguination to carcass entering the chiller] on muscle glycolysis and pork quality. Pigs negatively (using an electric goad) handled at the abattoir just prior to slaughter had lower muscle glycogen concentrations in the Longissimus thoracis (LT) and the Biceps femoris (BF) at all times post-slaughter and lower lactic acid at 5, 45 and 70 min post-slaughter compared to pigs minimally (no use of electric goads) handled prior to slaughter. Negative handling of pigs just prior to slaughter also resulted in pork which had higher surface exudate and a higher incidence of PSE compared with pigs minimally handled prior to slaughter. A prolonged rate of carcass processing resulted in reduced muscle glycogen in the LT and BF at all times post-slaughter. Delays in carcass processing rate also affected pork quality, as the meat was paler in comparison with pig carcasses that were processed without any delays. The results from this experiment have indicated that the use of electric goads to move pigs at the abattoir, and delays in carcass processing post-slaughter, can have a detrimental influence on ultimate pork quality.     

Effects of feed withdrawal before delivery on pork quality and carcass yield

A total of 270 pigs from a Yorkshire/Duroc/Landrace 3-way cross, reared under an ad libitum feed regimen, were delivered for slaughter after fasting (with access to water) for 24 and 0 h (Exp. 1), 16 and 0 h (Exp. 2) and 24, 16 and 0 h (Exp. 3). The interval between delivery and slaughter was 4-5 h. Feeding until delivery resulted in a lower pH at 45 min post mortem in the longissimus muscle. Ultimate pH values of longissimus and semimembranosus muscles were higher after feed restriction for 24 h. However, the incidence of dark, firm and dry (DFD) (pH > 6·2) was also increased after fasting in Exp. 1. Assessment of meat quality in samples taken from the longissimus at 20 h post mortem showed that, in comparison with feeding until delivery. Hunter L(?) (Lightness)-values and drip loss decreased and firmness improved by prolonged fasting (24 h). Fasting for 16 h did not reduce drip loss, but colour was improved (lower Hunter L(?)-values) in Exp. 3, although not in Exp. 2. Feeding until delivery resulted in better meat quality in Exp. 2 than in Exp. 1 and 3. A significant reduction in dressing percentage as a result of fasting was only found in Exp. 1. There appears no economic disadvantage in restricting feed for 16 h prior to delivery. Although the incidence of DFD may also increase, a fasting period of 16-24 h is recommended to reduce pale, soft and exudative (PSE) muscle, while losses in carcass yield are minimized. Other advantages of fasting are discussed.     

The effects of withholding feed and water on carcass shrinkage and meat quality in beef cattle

Eighty beef crossbred steers with an average weight of 493 kg (4·66 kg SD) were allocated at random to one of five treatments to assess the effects of withholding feed and water on carcass shrinkage and meat quality. The five treatments were: slaughter from the feedlot (T1); and 12, 24, 36 and 48 h periods without feed and water prior to slaughter (T2-5).Weights were taken of the live animal and the carcass to monitor shrinkage along with relevant meat quality measurements. There were no treatment differences (P > 0·05) in initial farm weight, but plant weight shrinkage increased from 31gkg(-1) for T1 to 106 g kg(-1) for T5. Warm carcass weight decreased (P < 0·05) from 278·8 kg for T1, to 270·7 kg for T3 and 261·9 kg for T5. Liver, alimentary tract components, hide and head decreased as a proportion of farm weight as time without feed and water increased. Muscle pH at 6 days post mortem was increased (P < 0·05) in T3-5 compared to T1, with the result that muscle colour became darker, and steaks had less drip loss. Shear values increased (P < 0·05) from 6·3 kg in T1 to 7·7 kg in T4 and T5 indicating an increase in muscle toughness as time without feed and water increased. It was concluded that steers lose live weight rapidly within the first 24 h without feed and water, and that these relatively short periods of time (24 h) can have detrimental effects on carcass shrinkage and muscle quality.     

Effects of age and/or weight at slaughter on longissimus dorsi muscle: Biochemical traits and sensory quality in pigs

The effect of increasing either age alone through feed restriction, or both age and weight at slaughter, on the quality of the longissimus dorsi muscle (LM) was investigated. Starting at 83 days of age and 32 kg, 80 pigs were allotted within litter to four experimental groups. All pigs were free of RYR1 mutated gene. Pigs were fed either ad libitum (A100, A130) or restricted 30% (R100, R130) and slaughtered at either 100 kg (A 100, R100) or 130 kg (A130, R130) body weight. Restricting feed intake in order to increase age at the same weight resulted in slower growth, better feed efficiency and increased leanness, whereas increasing age and weight simultaneously elicited slower growth, reduced feed efficiency and fatter carcasses. Intramuscular fat (IMF) and muscle collagen concentration were reduced by restricted feeding. Increase in both age and weight of pigs resulted in lower water, and higher protein and IMF concentrations. Although pigs were free of RYR1 gene, the PSE condition (defined as pH1 ≤ 5.9) developed in 25 carcasses, with a higher incidence in restricted pigs. PSE animals were excluded from the subsequent analysis of meat quality data. Feed restriction resulted in higher drip loss and lower a^* and c^* (saturation index) values. Longer myofibril fragments in muscle of restricted pigs on day 1 post mortem are indicative of slower maturation, while longer fragments on day 4 in heavier pigs, suggest that the extent of post mortem tenderisation could be negatively affected by the elevation of slaughter weight. Feed restriction had no significant effect on meat sensory quality, whereas increase in both age and weight resulted in lower tenderness, chewiness and mouth coating scores. Our results indicate that increasing age at a given body weight, via feed restriction, reduced IMF and collagen concentrations, and the rate of post mortem proteolysis, however, this had no significant impact on pork quality assessed after 4 days of ageing. On the other hand, increasing both age and weight at slaughter could alter pork texture, in spite of elevated IMF concentration.     

Potential interactions between the effects of preslaughter stress and post-mortem electrical stimulation of the carcasses on meat quality in pigs

The experiment examined the influence on pork quality of the electrical stimulation of carcasses from pigs subjected to different ante-mortem handling treatments. The carcasses were subjected to a slow chilling regimen to reflect less than ideal commercial practice. A total of 288 pigs (mean live weight 89 kg) of both sexes and a range of genotypes were used. They came from the Meat and Livestock Commission 's Pig Development Unit at Stotfold and were processed in 12 equal batches. Prior to slaughter they were transported for 2 h (80 km) at a stocking density of 0.5 m(2)/100 kg live weight. Preslaughter handling included being mixed or not with unfamiliar animals and being given a 3 h rest in lairage or not. One group received handling to simulate that in stunning races immediately before slaughter. There were no material interactions between the effects of ante- and post-mortem handling. Pigs rested 3 h in lairage had lower plasma cortisol levels irrespective of whether mixed with unfamiliar animals. Plasma lactate concentrations increased with greater ante-mortem stress. Pigs subjected to the simulated stunning race treatment had elevated carcass temperature. Greater ante-mortem stress progressively elevated pHu in the muscles and tended to reduce eating quality. Electrical stimulation followed by slow chilling raised initial muscle temperature, reduced pH(45) and pHu, and produced meat that was paler, had higher hue and saturation values and lost more drip during storage. Neither instrumentally-determined texture nor taste panel texture was affected, but electrical stimulation decreased juiciness and increased pork flavour. Overall eating quality was not affected by stimulation.     

Preslaughter resting and hot-fat trimming effects on the incidence of pale, soft and exudative (PSE) pork and ham processing characteristics

Effects of preslaughter rest (0, 1, 2 or 3 h) and hot-fat trimming (HFT, one side) on muscle quality characteristics of hams and loins were tested with 120 pigs. Center-cut loins from each carcass side were vacuum packaged and stored for 7 or 14 days at 2°C. Pigs not rested before slaughter had a skin temperature 3°C higher and ham muscle temperatures 1°C higher than pigs rested 1-3 h (P<0.05). Three hour muscle pH was highest if pigs were rested for 1 h. HFT significantly accelerated carcass chilling rate, but did not affect rate of muscle pH decline. After 14 days of aging, pigs not rested had lower sensory panel ratings for juiciness, tenderness, flavor and overall mouthfeel of loin chops than pigs rested 1 or 2 h. Percentage bound water of hams was highest (P<0.05) if pigs rested 1 or 2 h rather than a shorter or longer times. Pigs should be rested 1 h before slaughter and HFT carried out to allow more rapid carcass chilling and improve muscle quality.     

Investigations on genetically modified maize (Bt-maize) in pig nutrition: fate of feed-ingested foreign DNA in pig bodies

The passage and fate of ingested DNA in 48 pigs fed with diets containing (n=12) parental or (n=36) transgenic (Bt) maize were examined. Pigs were fattened from an initial live weight of 24 kg to approximately 108 kg. Animals fed transgenic maize were slaughtered in groups (n=6) 4, 8, 12, 24, 48 and 72 h after feeding the last maize-containing diet. Those slaughtered at up to 12 h received no further feed, while those held for longer prior to slaughter received a diet in which maize was replaced by barley and wheat. Control animals were slaughtered at 4 and 8 h. DNA extracted from tissues and gut contents was examined by PCR for the presence of plant DNA and for any transgenic material. Recombinant DNA was detectable in the intestinal contents up to 48 h after the last feeding of a diet containing the transgenic maize. PCR amplification of plant gene spacers produced fragments of different sizes, dependent on feed source. The feed source of rectum samples depended on individual passage rate in the groups and their restriction analysis showed grain species-specific patterns. Recombinant or maize-specific DNA was not detectable in tissue samples of pigs. In contrast, plant DNA fragments were detectable in the investigated pig tissues.     

Coherence of animal health,welfare and carcass quality in pork production chains

Aim of the study was to measure the potential impact of animal health and welfare on the carcass quality. 99 pigs under equal housing and feeding conditions were involved in the study. Effects of the immune system on carcass composition, meat quality and performance data of slaughter pigs became measureable by quantification of acute phase proteins (APP), haptoglobin (Hp) and pig major acute phase protein (Pig-MAP). The results were not significantly affected by gender or breed. The calculated correlations between chosen animal health indicators and carcass quality parameters prove an influence of health and welfare on performance, carcass composition and meat quality traits. The acute phase proteins could also be valuable as a predictive indicator for risk assessment in meat inspection, as increased Hp concentrations in slaughter blood indicate a 16 times higher risk for organ abnormalities and Pig-MAP concentrations above 0.7 mg/ml a 10 times higher risk.     

Effects of slaughter weight on carcass composition and meat quality in pigs of two different growth rates

Three hundred and forty (340) Duroc×(Landrace×Yorkshire) crossbred piglets were allotted to a 2×2×3 factorial design experiment. The independent variables were the growth rate (fast: around -10 days at 100kg and slow: around +2 days at 100kg), based on two different EBV's (estimated breeding value) of the sire-line for age, the sex (barrows and gilts) and the live weight at slaughter (107, 115 and 125kg). A sub-population of 119 pigs (10 carcasses per treatment) was selected for the carcass and meat quality evaluation trials. As live weight increased there were significant increases in hot carcass weight and dressing percentage (P<0.05). Lean, fat and bone proportions were not affected by weight. Gilts had higher lean proportion (P<0.05) than barrows. Furthermore, carcasses of fast growing pigs were fatter (P<0.05) than those of slower growing ones. Loin muscle pH, drip loss and reflectance values did not vary significantly with any of the treatments. Intramuscular fat was higher in barrows (P<0.05) than in gilts and soluble collagen content decreased with increasing weight (P<0.05). Muscle protein (%) increased (P<0.05) from 107 to 115kg and gilts had a higher (P<0.05) content than castrates. No evidence was found that increasing slaughter weight detracts from carcass characteristics or meat quality.     

Influence of dietary lysine level, pre-slaughter fasting, and rendement napole genotype on fresh pork quality

Sixty-four gilts from a commercial hybrid line were selected based on rendement napole (RN) genotype and live weight to evaluate the effects of feeding a lysine-deficient diet and feed withdrawal prior to slaughter on fresh pork quality. Glycolytic potential was measured and the bimodal distribution was utilized to predict RN genotype. Diets containing 4.8 (deficient) or 6.4 g/kg lysine were fed for the last six weeks prior to slaughter. Feed withdrawal treatments were imposed 12 or 36 h prior to slaughter. The lysine-deficient diet increased intramuscular fat content; however, feed withdrawal did not consistently impact fresh pork quality. Pork from RN carriers had a lower ultimate pH and Hunter L(*). Results from this study suggest that feeding a lysine-deficient diet can increase the intramuscular fat content of both RN genotypes, but feed withdrawal did not impact pork quality.     

Influence of food withdrawal at various times preslaughter on carcass yield and meat quality in sheep

Castrated male crossbred lambs were fed a complete pelleted diet ad libitum for 4 weeks prior to slaughter at a liveweight of about 32 kg. Forty lambs were killed directly off feed and forty each after 24, 48 and 72 h from food withdrawal. They had access to water at all times. Fasting had a significant effect on the weights of all body components examined except the combined fleece and feet. Liveweight was lost slightly more rapidly over the initial 24 h after food withdrawal, and this was attributable mainly to a 20% decrease in the weight of the gut contents. The overall rate of liveweight loss between 0 and 72 h was 0.14% h^?1. The corresponding loss of carcass weight was 0.085% h^?1, some reduction in yield being evident by 24 h of fast although a significant effect was seen only after 48 h. Liver weight was lost most rapidly (0.69% h^?1) over the initial 24 h but continued to be lost throughout fasting. Associated with the initial decrease in liver weight was a rapid loss of glycogen to very low levels by 24 h after food withdrawal. Fasting also reduced muscle glycogen concentrations but had no large or consistent effects on ultimate pH, reflectance or water-holding capacity.     

Effect of long term dietary supplementation with plant extract on carcass characteristics meat quality and oxidative stability in pork

The effects of dietary supplementation in pigs with plant extract (PE) from Lippia spp., titrated in verbascoside (5 mg/kg feed), from weaning to slaughter (166 days), on carcass characteristics, meat quality, collagen characteristics, oxidative stability and sensory attributes of Longissimus dorsi (LD) muscle were examined. Ten pigs per treatment were slaughter at a live weight of 109.5 ± 1.4 kg. No influence on carcass characteristics, LD meat quality parameters and collagen characteristics were observed. Dietary PE increased (P < 0.001) α-tocopherol levels in LD muscle. Raw LD of pig fed PE showed lower (P < 0.001) lipid oxidation levels than controls. A reduction (P = 0.05) of fat odor and rancid flavor intensity in cooked LD muscle stored at 4 °C for 24 h was observed in the treated group. This study shows that PE is an effective antioxidant in pork meat, enhancing oxidative status and sensory attributes, without affecting other meat quality parameters.     

Effects of feeding regimen and chilled storage on water‐holding capacity,colour stability,pigment content and oxidation in red deer (Cervus elaphus) meat

The effects of feeding regimen on carcass characteristics, meat colour and lipid stability, pigment content and water‐holding capacity of M. longissimus were studied in 16 male red deer. All animals were farm raised; eight were grazing pasture and eight were fed a pelleted commercial feed mixture for 10 weeks prior to slaughter. The pellet‐fed deer had significantly higher live weight, carcass weight, dressing yield (g kg^?1) and fat content than the pasture group. Carcasses from the pellet‐fed deer had higher temperatures over 0–10 h post mortem than carcasses from the grazing animals, probably due to an insulating fat cover. Ultimate pH values were lowest in meat from the pellet‐fed deer. The meat from the grazing deer had significantly better colour stability at 1 day post‐slaughter and after 1, 3 and 6 weeks of refrigerated storage (?1.5 °C) in vacuum bags. After 3, 6 and 12 weeks of refrigerated storage the meat from the pellet‐fed deer had significantly higher drip loss. No difference was found in the amount of oxidation products (thiobarbituric reactive substances, TBARS) when comparing the treatment groups, although the amount of TBARS increased during storage. Muscle pigment content was significantly higher in grazing deer than in the pellet‐fed group. It was not possible to confirm a correlation between lipid and pigment oxidation in the meat, and the pigment content of the meat samples did not seem to have an influence on colour stability or oxidation product formation. Copyright © 2005 Society of Chemical Industry     

The relationship between exsanguination blood lactate concentration and carcass quality in slaughter pigs

A group of 128 cross-bred barrows were used to determine the relationship between exsanguination blood lactate concentration ([LAC]) and carcass quality following commercial marketing conditions. After 10 h of feed withdrawal, pigs were loaded on a truck with a hydraulically lifted second deck and transported approximately 1 h to the slaughter facility. Pigs were rested for 8 h and stunned with carbon dioxide. Blood lactate concentration was measured on exsanguination blood. Fourteen pork quality measurements were obtained following normal post-mortem processing. Pearson correlations were used to determine the relationships between [LAC] and the meat quality parameters. Exsanguination blood lactate concentration ranged from 4 to 19.7 mM. Higher lactate was associated with lower 60 min pH (P = 0.0004) and higher drip loss (P = 0.02). These results suggest that under low-stress loading and standard marketing conditions, exsanguination [LAC] is predictive of the rate of early post-mortem metabolism.     

不同饲养方式下苏尼特羊肌纤维组成和羊肉品质的比较研究

本研究以6月龄苏尼特羊背最长肌为试验对象,分析三种饲养方式（放牧、放牧+补饲和舍饲）屠宰性能和肉品质的差异,通过ATPase组化染色法、肌球蛋白重链（Myosin Heavy Chain,MyHC）分子分型法对肌纤维类型进行定性及定量划分,并测定肌肉代谢酶活力,探究不同饲养方式肉品质产生差异性的内在原因。结果表明:放牧组的屠宰性能指标（总增重量、净肉重量、净肉率、屠宰率、产肉率）与胴体品质指标（背膘厚、胴体重）显著低于舍饲组和放牧+补饲组（P<0.05）,放牧组的骨肉比显著高于舍饲组和放牧+补饲组（P<0.05）。放牧+补饲组和放牧组pH_{24 h}显著低于舍饲组（P<0.05）,放牧组剪切力值显著低于舍饲组（P<0.05）。放牧组和放牧+补饲组Ⅱb型肌纤维直径和面积比例显著低于舍饲组（P<0.05）,MyHCⅡb mRNA表达量显著低于舍饲组（P<0.05）。放牧组Ⅰ型、Ⅱa肌纤维直径和横截面积、乳酸脱氢酶（lactic dehydrogenase,LDH）活力均显著低于舍饲组（P<0.05）,舍饲组肌纤维密度、Ⅱa数量比例及面积比例、MyHCⅠmRNA表达量、苹果酸脱氢酶（malate dehydrogenase,MDH）活力显著低于放牧+补饲组和放牧组（P<0.05）,MyHCⅡx、MyHCⅡa mRNA表达量和琥珀酸脱氢酶（succinate dehydrogenase,SDH）活力均显著小于放牧组（P<0.05）。综上所述,相比于自然放牧的苏尼特羊,舍饲和放牧+补饲的饲养方式下屠宰性能和胴体品质更优,而放牧和放牧+补饲的饲养方式由于能增强肌肉的氧化代谢能力且氧化型肌纤维比例更高,一定程度上肉品品质更好。     

不同饲养条件对苏尼特羊背最长肌中MyomiRs表达及屠宰性能的影响

选择不同饲养条件下12月龄苏尼特羊的背最长肌为实验材料,通过测定6种mi RNAs的表达量及苏尼特羊的屠宰性能,研究不同饲养条件对mi RNAs表达量及屠宰性能的影响。结果表明:放牧苏尼特羊生长性状(体长、体高、胸围)、宰前活质量、胴体质量均显著高于圈养(P0.05),圈养苏尼特羊屠宰率、净肉率高于放牧。放牧苏尼特羊mi RNAs表达量均高于圈养苏尼特羊。放牧苏尼特羊mi R-1表达量与体高、胴体质量、净肉质量、净肉率显著正相关(P0.05),mi R-133表达量与净肉质量呈显著正相关性(P0.05),圈养苏尼特羊mi R-128表达量与净肉率显著负相关(P0.05)。说明不同饲养条件对mi RNAs的表达有影响,进一步影响屠宰性能。     

Strategic finishing feeding as a tool in the control of pork quality

A standard diet and two finishing feeding strategies known to reduce muscle glycogen stores were investigated in combination with exercise immediately prior to slaughter in pigs. The objective was to determine the influence of muscle glycogen at slaughter on temperature and pH in post-mortem muscle, the colour, drip loss and Warner–Bratzler shear force of the meat. The muscle glycogen stores were reduced by strategic finishing feeding. In general, pH_{45 min} was higher in muscles from strategically fed pigs compared with control pigs. Exercise also resulted in higher pH_{45 min} in control pigs compared to non-exercised control pigs, while the opposite was seen in muscles from strategically fed pigs. Exercise resulted in higher muscle temperatures in the carcasses irrespective of feeding strategy. pH_{24 h} were higher in M. biceps femoris and M. semimembranosus from exercised, strategically fed pigs compared with the corresponding controls. In contrast, irrespective of feeding strategy no difference in pH_{24 h} was registered in the meat of non-exercised pigs. Drip loss was lower in meat of strategically fed pigs compared with meat of control pigs. Moreover the drip loss was lowest in the meat of non-exercised pigs. The present study shows that strategic finishing feeding has high potential for the control of pork quality.     

Comparison of different dietary magnesium supplements on pork quality

Forty-eight crossbred (Large White×Landrace) boars were used to compare the effect of dietary magnesium aspartate (MgAsp), magnesium sulphate (MgSO(4)) and magnesium chloride (MgCl(2)) on muscle glycogenolysis and pork quality. The pigs were fed finisher feed supplemented with either MgAsp, MgSO(4) and MgCl(2) for 5 days prior to slaughter. At the abattoir, all pigs received 15 electric shocks from an electric goad 5min prior to slaughter. Pigs fed the diet supplemented with MgSO(4) had the highest plasma Mg concentrations at slaughter in comparison with pigs fed the MgAsp and MgCl(2) supplemented diets. There were no differences in plasma adrenaline and noradrenaline concentrations at slaughter between the different diets. Pigs fed the Mg diets had higher muscle glycogen concentrations in the Longissimus thoracis (LT) muscle at 5min and at 40min (except MgCl(2)) post-slaughter compared to pigs fed the control diet. Also pigs fed the Mg diets had lower muscle lactic acid concentrations in the LT at 5min post-slaughter and lower drip loss at 24hr post-slaughter compared to pigs fed the control diet. These results indicate that cheaper magnesium sources, MgSO(4) and MgCl(2), are as efficacious as MgAsp in reducing drip loss and improving pork quality.