The effect of increasing carcass weight of finishing boars and gilts on joint composition and meat quality

Two hundred and eighty-eight crossbred (3/4 Landrace × 1/4 Large White) pigs, comprising equal numbers of boars and gilts, were housed in single sex groups from 50 kg liveweight to slaughter at liveweights of 92, 105, 118 and 131 kg (carcass weights of 70, 80, 90 and 100 kg). Sample joints from the left longissimus dorsi muscle were obtained at slaughter for dissection and meat quality assessment. As carcass weight increased there were significant (p<0.001) increases in eye muscle area and subcutaneous fat content. Lean content decreased (p<0.001) with increasing carcass weight while intermuscular fat content was not affected. There was a significant interaction between carcass weight and gender with % drip loss in pork from gilts at 100 kg having a higher drip loss than boars and gilts at all other weights. There were small but significant (p<0.01) reductions in ultimate pH with increasing carcass weight. Cooking loss was also reduced (p<0.001) at the heavier weights. There was no effect of carcass weight on shear force or on intramuscular fat. Dry matter (DM) and crude protein (CP) contents of m. L. dorsi increased (p<0.001) at heavier weights while sarcomere length decreased (p=0.001). Compared with boars, gilts had greater eye muscle area (p<0.05), more subcutaneous fat (p<0.001). Meat from gilts in comparison with boars had higher % DM and % CP contents (p<0.001), higher intramuscular fat content and shear force (p<0.05). It is concluded that meat quality may be improved when carcass weight is increased from 70 to 100 kg. ?     

The effect of feed withdrawal during lairage on meat quality characteristics in ostriches

Commercially reared ostriches (n = 84) were randomly allocated to one of two groups. The first group (stressed: n = 38) was deprived of food for a period of 2.5 days prior to slaughter, to simulate the stress experienced by slaughter ostriches held in holding pens (lairage) at a commercial ostrich abattoir over a weekend. The second group (control: n = 46) was fed normally until 24 h prior to slaughter. Initial live weight as well as hot and cold drumstick weight were independent (P > 0.05) of treatment. Stressed birds lost on average (±SE) approximately three times more weight than control birds over the experimental period (−3.2 ± 0.6 vs. −1.0 ± 0.5 kg, respectively). Full stomach and alimentary tract weights did not differ between treatments although there was a tendency for that derived from stressed birds to have lower stomach contents. The intra-muscular (Muscularis iliofibularis) pH_f of stressed birds was 0.22 units higher (P < 0.01) than that of contemporaries in the control group 1 h post-slaughter (6.03 ± 0.06 vs. 5.81 ± 0.05, respectively). After 26.5 h in a refrigerated room, this difference still remained at 0.25 units (6.46 ± 0.07 vs. 6.21 ± 0.07, respectively; P < 0.05). Post-slaughter changes in intra-muscular pH followed approximately the same trend in stressed and control birds. Intra-muscular temperature was largely independent of treatment, although there was a suggestion of a slightly higher (P = 0.18) temperature in stressed birds immediately post-slaughter. Cooking loss, drip loss and shearing values were not affected (P > 0.05) by the withholding of food for 2.5 days. It can thus be concluded that withholding feed from ostriches on lairage over a period of 2.5 days does not have any negative influence on the meat yield or physical quality traits thereof.     

The cumulative effect of nutritional, shearing and preslaughter washing stresses on the quality of lamb meat

Carcass and meat characteristics were measured in lambs exposed to combinations of nutritional, shearing and preslaughter washing treatments. Both shearing and a low plane of nutrition reduced carcass weight (P < 0·001) and increased carcass leanness (P < 0·01). Tenderness and colour of M. longissimus dorsi were not significantly influenced by treatments even though there were substantial responses in meat pH. In lambs subjected to all three stressors pH was 0·40 units above control levels, significantly more than the sum of individual effects (P < 0·05), demonstrating a cumulative effect of stressors on meat pH.     

The effect of food deprivation prior to slaughter on performance, behaviour and meat quality

The effects of repeated food deprivation, prior to slaughter, on performance, feeding behaviour and meat quality of pigs was examined. Three experimental treatments were compared. In treatment 1 pigs had ad libitum access to feed up to the point of loading on the day of slaughter. Treatment 2 involved a 12-h fast prior to slaughter and treatment 3 involved a 20-h fast prior to slaughter. Pigs were slaughtered on a weight basis therefore each pen was emptied over a period of weeks. This meant some pigs experienced repeated food deprivation. The feeding pattern of pigs which were deprived of food for 12 h was very similar to that observed before feed restriction. Pigs which were deprived of food for 20 h spent significantly more time at the feeder post fasting. This was particularly marked during the first 2–3 h when access to feed was restored. Feed deprivation for 12 h prior to slaughter did not adversely affect performance, carcass weight, meat quality or welfare in the present study. Fasting for 20 h reduced carcass weight by 1 kg, which was not statistically significant but could result in financial losses related to carcass weight. The negative effects on meat quality, of repeated feed deprivation, resulted from slower growth rates rather than feed deprivation per se.     

牲畜的宰前运输对肉品品质的影响

大量研究结果表明,不合理的运输方式和运输时间会引起牲畜体内水分流失,从而引起体重下降;宰前运输产生的强烈应激会导致牲畜糖原损失,产生高的极限pH,进而极大地影响肉品品质.本文综述了运输过程中牲畜体重下降、糖原损失的研究情况,对可能出现的影响肉品品质的问题做了具体的阐述,对其机理进行了简单的介绍,并提出了一定的解决措施.以期为国内的相关研究及生产实际提供一些参考.     

Effect of lairage duration on rabbit welfare and meat quality

This study determined whether short (2 h) or long (8 h) lairage at an abattoir had an effect on plasma stress indicators (haematocrit, glucose, lactate, creatine phosphokinase and corticosterone), instrumental meat quality (pH24, water holding capacity, colour, raw and cooked texture) and sensory meat quality (using a trained sensory panel) in rabbits. The effect of the position of the animals on a multifloor rolling cage stand during lairage was also assessed. Lairage time had a significant effect on blood stress indicators, but only a slight effect on meat quality traits. A lairage duration of 6–8 h is recommended.     

Effects of diet and live weight at slaughter on kid meat quality

Forty male twin kids of the Majorera breed were used in a 2×2 design, in which the diet, suckled on dam (SD) or milk replacer (MR) and live weight at slaughter (6 or 10kg) were the main variables. Muscle pH and colour (CIE, L*a*b*) were determined in the longissimus (LD), semimembranosus (SM) and triceps brachii (TB) muscles, immediately after slaughter and chilling (24h). Water-holding capacity, shear force, chemical composition (moisture, fat, protein and collagen content and solubility) were determined. Muscle fibre populations were also studied. SD kid meat was slightly more tender and juicy, and the Chroma value was lower than in MR animals. The meat from the kids that were slaughtered at 10kg was significantly darker in all muscles tested and slightly less tender 6kg LWS kid meat had more moisture and less protein than that of 10kg LWS kids. Muscle fibre area was statistically higher in the 10-kg LWS kids. It was concluded that the meat quality of the heavier kids was not significantly different from that of the lighter kids and that slaughter at the greater weight would result in more meat being marketed.     

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.     

Low stress pre-slaughter handling: effect of lairage time on the meat quality of pork

The effect of lairage time on meat quality was investigated when crossbred pigs were subjected to low stress pre-slaughter handling, where pigs were treated in mixed groups of 15 from the farm to group CO(2) stunning, and where electric goads were not used at any time. Two experiments were carried out, one in spring (n=270) using very standardised conditions and one producer, and one in summer (n=630) using a representative randomly chosen sample of producers. In the first experiment three lairage times were used, less than 30 min (average 26 min), 90 min (average 83 min) and more than 150 min (average 170 min) and no showering. The pH and temperature were measured in the m. longissimus dorsi at various times post mortem, and colour (L(*), a(*), b(*)), internal reflectance and drip loss the day after slaughter. Sensory evaluation was carried out on 16 randomly chosen samples from the shortest and longest lairage time groups. Drip loss, pH(ultimate) and internal reflectance were also measured in the m. biceps femoris and pH(ultimate) and internal reflectance in the m. semimembranosus. Finally, pH(ultimate) was measured in the m. semispinalis capitis. In the second experiment only two lairage times were used, less than 30 min (average 17 min) and more than 130 min (average 150 min) and with intermittent showering and only a subset of the meat quality measurements were made. Lairage time had no effect on any of the meat quality parameters measured in experiment 1. In experiment 2 the shortest lairage time led to a higher temperature in the m. longissimus dorsi at 2 min post mortem, a higher drip loss in the m. biceps femoris and higher internal reflectance values in both muscles the day after slaughter. The differences were, however, very small and may have been an effect of showering.     

Bayesian meta-analysis of the effect of fasting, transport and lairage times on four attributes of pork meat quality

Technological meat quality is a significant economic factor in pork production, and numerous publications have shown that it is strongly influenced both by genetic status and by rearing and slaughter conditions. The quality of meat is often described by meat pH at different times postmortem, as well as by color and drip loss. A meta-analysis based on a database built from 27 studies corresponding to a total of 6526 animals classified was carried out. The purpose of this meta-analysis was to study the effect of fasting, lairage and transport durations on four main attributes of the technological pork meat quality. A Bayesian hierarchical meta-regression approach was adopted.The results of our meta-analysis showed that fasting time had a significant effect on pH measured 24 h post-mortem (pHu) and drip loss (DL) measured in longissimus muscle. While, lairage affected only the pHu in semimembranosus muscle. Interestingly, we found that DL was the lone attribute that was affected by transport time and its interaction with fasting time.     

Influence of lairage environmental conditions and resting time on meat quality in pigs

This study investigated the influence of lairage environmental conditions and resting time on pig carcasses and meat quality. The experimental material consisted of 1001 cross Pietrain-Duroc-Hampshire × Belgium-LR-LW pigs, held in lairage for either ≈30 min (direct slaughter) or between 2-3 h under 12 °C/90% relative humidity (RH), 20 °C/80% or 90% RH and 35 °C/50% or 85% RH. Prior to arrival at the lairage plant they were transported for about 45-60 min and subjected to a fasting period of 36 h before loading. Unloading operation and the driving of pigs to the point of stunning were carried out according to the practices used in the plant (sticks and electrical goads were used). Batches of 20-30 mixed pigs were used in each trial, held at a stocking density of approximately 0.55 m(2)/pig (≈100 Kg live weight). Lairage environmental conditions (LC), significantly affected almost all measurements, but not pH(1), in Semi-membranosus (SM) and Longissimus dorsi (LD) muscles and the carcass damage score. The influence of resting time (RT) was basically exerted on pH(u), deep ham temperature and in pH(1), of SM, the internal muscle reflectance being mostly unaffected. There were also significant batch (B) effects in a large range of parameters. Factors greatly interacted their influence on carcass and meat quality, denoting LC × B, LC × RT × B and LC × RT the most significant effects. RT × B only showed two low significant interactions for rigor value and pH(1), in SM, suggesting that, conversely to the lairage environmental conditions the influence of resting time is practically unaffected by the day of slaughter. The increase of lairage temperature decreased the frequency of normal carcasses, followed by an expressive higher incidence of PSE status. The influence of lairage relative humidity on the PSE/DFD muscle incidence depended on the associated temperature, but the most important detrimental effects were noticed in experiments carried out at 35 °C. In respect to lairage resting time, the influence on meat quality is strictly related to environmental conditions, mainly the temperature. Nevertheless, and excepting the assays at 35 °C/85% RH, direct slaughter of pigs (= 30 min in pens) generally produced less carcasses of normal quality than resting periods up to 2-3 h.     

pH值对屠宰肉品质的影响

介绍了pH值的概念、pH值在家畜屠宰过程中的作用、pH值对内制品品质的影响.论述了pH值对内及肉制品产品加工的特性,通过控制加工过程中产品的pH值来保证产品质量.     

Influence of feeding systems on cortisol levels,fat colour and instrumental meat quality in light lambs

Forty-eight lambs were fed as follows: GR, lambs and dams grazed perennial pasture; GR+S, the same as GR except that lambs had access to concentrate; DRL-GRE, lambs in drylot and dams in rationed grazing; DRL, lambs with dams were stall-fed. DRL-GRE and DRL lambs were weaned at 45 days of age. Lambs were slaughtered when they reached 22–24 kg of live weight. Plasma cortisol concentration was determined three times before slaughter. Subcutaneous fat and meat colour, and texture were analysed.     

Finishing diet,temperament and lairage time effects on carcass and meat quality traits in steers

Sixty Hereford (H) and Braford (B: 3/8 Zebu and 5/8 H) steers were finished on: D1) rangeland plus corn grain (1% of live weight) (H n = 15, B n = 15); and D2) high quality pasture (H n = 15, B n = 15) to study the effect of diet, temperament and lairage time on carcass and meat quality. Steers were slaughtered the same day in two groups, spending 15 and 3 h in pens, respectively (50% from D1, 50% from D2 in each group). Animals from D1 had better carcass performance without effect of the diet on meat quality. Regardless of breed, calmer steers showed higher average daily gain and lower shear force values. Carcasses from animals in the long lairage group had a better rate of pH decline and more tender meat, suggesting that more than 3 h preslaughter time should be necessary to rest and recover, mainly depending on lairage conditions.     

Influence of age at slaughter, rearing technique and pre-slaughter treatment on some quality traits of lamb meat

The influences of rearing technique and age on muscle fibre type, and of rearing technique, age and pre-slaughter transport on the meat quality characteristics of sheep were investigated using thirty lambs of a Bulgarian coarse-fleeced breed (Karakatchanska). The animals were reared on pasture or in barns and slaughtered at 22 or 30 weeks of age. Muscle fibre type and meat quality were studied in three muscles of different metabolic type—Longissimus dorsi (LD), Supraspinatus (SS) and Rectus abdominis (RA). Fibre type distribution was influenced by age but not by rearing technique. Pigment content of muscles was higher in older animals. Water binding capacity (WBC) increased—and cooking loss decreased—with age. There was an interaction between muscle and pre-slaughter stress with respect to pH, the latter being increased in SS muscle, as was WBC. Cooking loss was decreased by transport stress in the three muscles and by pre-slaughter stress. However, meat organoleptic characteristics (flavour, tenderness and juiciness, as judged by a taste panel) were not influenced by age, rearing technique or pre-slaughter treatment.     

Lean meat prediction with HGP, CGM and CSB-Image-Meater, with prediction accuracy evaluated for different proportions of gilts, boars and castrated boars in the pig population

Prediction equations for the percentage lean meat in pig carcasses in The Netherlands were derived for the Hennessy Grading Probe 7, Capteur Gras/Maigre — Sydel and CSB-Image-Meater. Because castrated males are expected to vanish from the Dutch pig population in the near future, accuracy of prediction was evaluated for different scenarios representing a wide range of different proportions for entire males, castrated males and females in the Dutch pig population. The prediction equations for the instruments are in compliance with the EC regulations for prediction accuracy for the different scenarios. So, these equations will remain valid when castrated males are (gradually) removed from the Dutch slaughter population. Results of this study are of interest for researchers from countries or areas contemplating the use of one of the aforementioned instruments. The statistical approach for evaluation of prediction accuracy is of particular interest when changes in proportions of important subpopulations in the target population are foreseen.     

Effects of lairage time on welfare indicators,energy metabolism and meat quality of pigs in Beijing

A total of forty Duroc–Landrace–Large White female pigs (90 ± 5 kg) were used to study the effects of different lairage times (0 h, 3 h, 8 h, 24 h) on welfare, energy metabolism and meat quality. The results showed that lairage time of 3 h led to a lower blood cortisol, a decreased drip loss and a delayed degradation of glycogen in muscles compared with pigs without rest, while lairage times of 8 h and 24 h resulted in a significant increase in pork toughness. It was concluded that three hours of lairage was appropriate to reduce pre-slaughter stress and obtain better meat quality for pigs transported for 4 h in winter, under the most frequent commercial conditions in Beijing, China. No lairage, or excessively long lairage time, might compromise animal welfare and meat quality.     

茶皂素对肉仔鸡生长性能、屠宰性能和肉质的影响

在肉鸡日粮中添加茶皂素,研究其对肉鸡生长性能、屠宰性能和肉质的影响.对照组饲喂基础日粮,试验1、2、3和4组在基础日粮的基础上分别添加200、300、400和500 mg/kg的茶皂素,试验期为56天.结果表明:与对照组相比,4组平均日增重提高8.74%(P＜0.05)、料重比降低15.52%(P＜0.01)、屠宰率提高2.33%(P＜0.05);2、3组料重比降低了5.60%、10.34%(P＜0.05);1、2组腹脂率降低了6.92%、9.69%(P＜0.05),3、4组腹脂率降低15.92%、15.57%(P＜0.01);2组滴水损失降低5.42%(P＜0.05),而3、4组滴水损失降低11.19%、14.24%(P＜0.01).     

Effect of preslaughter handling on muscle glycogen level and selected meat quality traits in beef

The ante-mortem and post-mortem glycogen levels in bull muscle were studied to determine their influence on the ultimate pH, cooking loss and shear force. Forty-three bulls (13 Holstein, 12 crosses Holstein × Belgium blue, 9 Slovak Pied and 9 crosses Slovak Pinzgauer × Piemontese) were tied, housed and divided in control (A, n = 30) and stressed (B, n = 13) groups before slaughter. At the institute abattoir, the group B animals were mixed and kept overnight. In group A, bulls were slaughtered immediately after arrival at the abattoir. The following values of muscle were determined: (1) glycogen ante mortem from m. semitendinosus (ST) (biopsy technique, Biotech Nitra), (2) glycogen post mortem (1 hr, 3 hr, 48 hr) from longissimus dorsi muscle (LD), (3) ultimate pH, cooking loss and shear force 48 h post mortem. The results show that the glycogen concentrations ante mortem (ST) and 1 hr post mortem (LD) from unstressed animals were similar (p > 0.05). The ante-mortem and post-mortem (1 hr, 3 hr) muscle glycogen concentration were depleted (p < 0.01) in all stressed bulls. Differences between stressed and unstressed animals (p < 0.01) were found in ultimate pH, cooking loss and in shear force (p < 0.05). Significant correlations (p < 0.01) between ante-mortem (ST) and postmortem (LD, 1 hr, 3 hr) muscle glycogen and ultimate pH and cooking loss supported the possibility of using an efficient biopsy technique in combination with a simple method of glycogen estimation (iodide method) to predict metabolic exhaustion (glycogen depletion) and/or dark cutting condition of bulls.