The effect of conditioning period on loin muscle tenderness in crossbred lambs with or without the Texel muscling QTL (TM-QTL)

A Texel muscling quantitative trait locus (TM-QTL) has been identified on chromosome 18, which increases loin muscling, but may also have a negative impact on mechanically-measured loin tenderness in crossbred lambs, depending on conditioning time. This study investigated the influence of a range of conditioning times (3, 5, 7 or 9 days) on the effect of TM-QTL on loin muscle tenderness. Using Texel rams heterozygous for TM-QTL, mated to non-carrier Mule ewes, heterozygous (n = 45) and wild-type (n = 50) crossbred lambs were produced. Weight of the valuable Longissimus lumborum muscle was higher in TM-QTL carriers than non-carriers, when compared at a fixed age (+11.5%; P = 0.038), with the same trend at a fixed carcass weight (+10.2%; P = 0.064). Toughness, measured by shear force, was significantly higher in samples from TM-QTL carriers than non-carriers, after conditioning for 3 days (P = 0.002), 5 days (P = 0.003) or 7 days (P = 0.03), but was not significantly different after 9 days of conditioning (P = 0.32). Compared to non-carrier lambs, the proportion of samples above consumer acceptability thresholds for toughness was greater in the TM-QTL carrier lambs after 3 and 5 days of conditioning, similar at 7 days, but lower at 9 days. The results suggest that the negative effect of TM-QTL on loin tenderness in crossbred lambs can be overcome by conditioning for more than 7 days. Marketing of TM-QTL carrier lambs through companies that use enhanced processing protocols could be beneficial, due to higher loin muscle weights, without negative effects on meat quality.     

Effects of genetic variants for the calpastatin gene on calpastatin activity and meat tenderness in Hanwoo (Korean cattle)

This study was designed to investigate the effects of calpastatin genotypes determined by PCR-SSCP (polymerase chain reaction-single strand conformation polymorphism) on calpastatin activity (CAC) and Warner-Bratzler Shear Force (WBS). Longissimus muscles were prepared from 379 Hanwoo bulls aged approximately 20 months. The selection of PCR primers was based on exons (27 and 28) of the bovine calpastatin cDNA sequences, and genetic variants were detected by SSCP analysis using Taq I restriction enzymes. Sequencing analysis confirmed 4 restriction sites (nucleotide positions 52, 67, 796, and 1369), and a genetic variant was verified at a nucleotide position 641 (C/T substitutions) based on sequences (AF281256). The CAST28 genotypes showing allele frequencies of C (0.429) and T (0.571) were significantly associated with CAC and WBS. A significant positive residual correlation (r = 0.121, P = 0.02) between CAC and WBS was obtained.     

The effect of growth rate and ultimate pH on meat quality of lambs

Entire male Romney lambs (n = 60) were grown slowly (67 g/day) and slaughtered at 14 months of age at an anticipated carcass weight of 18 kg. Another group of ram lambs (n = 15) from the same genetic background (born 7 months later) were grown rapidly (162 g/day) for 7 months and slaughtered at the same time and at a similar carcass weight. Preslaughter shearing (20 days prior to slaughter) and swim washing (3 times) were variously imposed upon the 14-month old lambs to give them a graded preslaughter stress. The lambs were head-only electrically stunned and slaughtered. Dressed carcasses were electrically stimulated at 20 min post mortem for 90 s at 14·3 pulses/s, 1·8-2 A and 1130 V peak, then held at 12°C for 2 h and frozen so that the deep leg reached -4°C in 12 h. The ultimate pH was measured for the longissimus dorsi, and loin samples were assessed by tenderometer and a sensory panel. The groups with the greatest stresses imposed had the highest ultimate pH. The most tender meat came either from carcasses with an ultimate high pH greater than 6·3 or from young lambs with an ultimate pH from 5·5-5·7. While 7-month old lambs were slightly more tender than the 14-month old lambs of iso pH, the 14-month old lambs of high pH were the most tender. This suggests that age-related connective tissue effects were minimal for the loin. The shear force values and taste panel tenderness scores were linearly related. When the shear force and panellists' tenderness scores were expressed in relation to ultimate pH, there was a decreased acceptance of meat with a moderate ultimate pH between 5·8 and 6·0. Panel texture assessments showed a less clearly defined, but statistically significant decrease in acceptance at pH 5·8-6·0. Other sensory attributes of flavour, juiciness and aroma were uniform across the whole ultimate pH spectrum.     

The effect of selection for growth rate on carcass composition and meat characteristics of rabbits

The effect of selection for growth rate on carcass composition and meat quality was assessed by comparing two groups of rabbits belonging to different generations of a selection experiment. A Bayesian approach was used. Embryos belonging to generations 3 and 4 of selection were frozen and thawed to be contemporary of animals from generation 10. A control group (C), formed from offspring of these embryos, was contemporary to offspring of generations 10 and 11 of selection, chosen at random, which constituted the selected group (S). One hundred and thirty-one contemporary rabbits were slaughtered at approximately the Spanish commercial live weight of 2 kg. Carcasses were dissected and measured according to the norms of the World Rabbit Scientific Association. An animal model including effects of genetic group (C, S) and sex, and slaughter weight as a covariate was used. S animals had a higher development of liver, kidneys and of a set of organs consisting of the thymus, trachea, oesophagus, lung and heart, relative to C. For dissectible fat, S animals had less than C: −0.31 g for scapular fat, −1.62 g for perirenal fat and −2.03 g for inguinal fat. S had a lower content (−0.39%) of dissectible fat percentage in the “Reference” carcass, indicating a lower degree of maturity at slaughter. The meat to bone ratio was not affected by selection, but the meat and bone contents of the hind leg were 3.25 and 0.71 g higher, respectively, in the C group. Selected animals had a lower water holding capacity in the raw meat (−2.10%), a higher water holding capacity in the cooked meat (2.17%), a higher cooking loss (3.31%) and a lower fat percentage in the meat of a hind leg (−0.37%). Females had more fat than males: 0.26 g for scapular fat, 1.02 g for perirenal fat, 1.10 g for inguinal fat, and 0.24% for total dissectible fat percentage of the “Reference” carcass.     

The effect of experimental stress on sarcoplasmic reticulum Ca transport and meat quality in pig muscle

Stress before slaughter affects the meat quality of pigs and a disorder in the Ca²⁺ transport of the sarcoplasmic reticulum (SR) results in inferior meat quality. The object of this work was to determine the impact of stress on SR Ca²⁺ transport in pig muscle in animals with no mutation in the Ca²⁺ release channel. At about 80 kg live weight, pigs were stressed either by running for 4 min (n=9) or by a 5 min application of a nose snare (n=7). Immediately before and after the application of the stress, as well as 4 h after the stress, biopsy samples of the longissimus muscle were taken and the Ca²⁺ uptake of the homogenised muscle samples determined. The nose snare stress reduced the rate of Ca²⁺ uptake by 9% (P=0.02) and running by 18% (P=0.06). Uptake in samples taken 4 h after the stress was at initial levels. The pigs were slaughtered at an average live weight of 109 kg. Half the pigs were stressed just before slaughter for 5 min by the use of a nose snare. Immediately after exsanguination longissimus muscle samples were taken, Ca²⁺ uptake measured, and later standard meat quality parameters were determined. Although the stress reduced the Ca²⁺ uptake rate (61.3 vs. 46.4 nM/min per mg protein for control and stressed pigs; P=0.04), the meat quality was not significantly affected.     

Effect of suckling management on productive performance,carcass traits and meat quality of Comisana lambs

The effect of restricted suckling on productive performance, carcass traits, meat quality and skeletal development of growing lambs was studied. Twenty-one naturally suckled male Comisana lambs were divided into three equal weight groups differing in suckling management systems: (1) only maternal milk (C); (2) only maternal milk until 15th day of age, and then, till slaughter, maternal milk, concentrate and Lucerne hay ad libitum (T1); (3) only maternal milk until 15th day of age, and then from 16th to 30th days of age, maternal milk, concentrate and Lucerne hay ad libitum, and, from 31st day of age till slaughter, only concentrate and Lucerne hay ad libitum (T2). The total mean milk yield was 22.7 and 41.6 kg per ewe for T1 and T2, respectively. Restricted suckling did not significantly affect slaughter weight, hot and cold carcass weights, carcass shrink losses, pH, colour and area of Longissimus muscle, pelvic limb, or bone characteristics. Suckling management system significantly affected ADG, milk intake, dressing percentage, and percentages of intestine, stomach, offal, kidney fat, shoulder, lean and fat, and there were differences in total collagen, and hydroxylysylpyridinoline crosslink concentrations. In addition, different IMC maturity among the muscles was apparent.     

高压和热结合处理对鸡肉pH、嫩度和脂肪氧化的影响

对不同温度(20～70℃)下高压(0.1～800MPa)处理20min对鸡胸肉pH、嫩度和脂肪氧化的影响进行了研究。结果显示,压力和热或两者结合处理都能使肌肉的pH升高,但两者结合处理对pH的影响无叠加作用。单纯的热处理过程中,随着温度的升高,肌肉的嫩度持续下降,同样,室温下的压力处理时,肌肉的嫩度随压力的升高而降低。40℃时压力处理,肌肉嫩度的变化与室温下相似。然而,当在60℃和70℃温度下压力处理时,200MPa的压力导致肌肉的嫩度显著提高。其原因可能为在此条件下肌肉骨架蛋白质发生了降解。压力和热以及两者结合处理都能加速脂肪的氧化,尤其是在400MPa及其以上压力。压力和热处理导致脂肪氧化的原因,可能与肌肉结构的破坏及过渡金属离子(如铁离子)的释放有关。     

The effect of supplementation with expanded sunflower seed on carcass and meat quality of lambs raised on pasture

The use of conventional concentrates in the supplementation of grass-based fed lambs may induce improvements in growth performance and/or carcass quality but may be disadvantageous in fatty acid profile of tissues, with a negative impact in some nutritional indexes. The objective of this trial was to evaluate the effects on growth performance, carcass and meat quality of using unprotected, unsaturated fat as a supplement for grass-fed based lambs. Twenty-four Merino Branco ram lambs raised on pasture, were supplemented with corn whole grain plus sunflower meal or corn whole grain plus expanded sunflower seed, from 20 to 30 kg live weight. The supplement had no effects on growth performance, carcass quality traits, or meat pH, colour estimates (L^*, a^*, b^*), water-holding capacity, shear force and sensorial attributes. However, lambs supplemented with expanded sunflower seed showed higher proportions of cis-9, trans-11 octadecadienoic acid and trans-vaccenic acid in intramuscular and subcutaneous fat, showing that the inclusion of unprotected lipids in lambs diet was effective in preventing the reduction of rumenic acid (C18:2 cis-9, trans-11) that occurs when conventional concentrates are used as a supplement.     

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.     

Effect of concentrate level and slaughter body weight on growth performances,carcass traits and meat quality of Barbarine lambs fed oat hay based diet

This study was conducted to evaluate concentrate level (CL) and slaughter body weight (SW) effects on growth performances, carcass traits and meat quality of Barbarine lambs. Twenty-four weaned male lambs (23.1 kg), receiving an oat-hay based diet, were allotted into two groups. The LCL group received low concentrate level (300 g) and the HCL group received high concentrate level (600 g). Lambs were slaughtered at two prefixed weights (35 and 42 kg). For each group and each weight, six lambs were slaughtered. Lambs from HCL group had higher ADG, carcass yields, carcass compactness and subcutaneous fat thickness, and lower carcass meat proportion. CL increase did not affect meat pH, meat and fat color, chemical and fatty acid composition. Late slaughtering improved carcass yields and increased carcass adiposity. However, it did not affect carcass meat proportion and shoulder tissue composition. SW had effect on meat color and fatty acid composition.     

Effect of lipid type on growth performance,meat quality and the content of long chain n − 3 fatty acids in pork meat

The aim of the present study was to produce pork with enhanced nutritive value for humans, both in terms of fatty acid profile (mainly long chain n − 3 fatty acids by feeding fish oil) and selenium. Forty-eight female pigs were allocated to one of six treatment groups: animal by-products and plant feedstuffs with tallow, plant feedstuffs with a blend of soybean oil and linseed oil with or without a supplement (CLA, selenium, vitamin E and vitamin C), plant feedstuffs with tallow and supplement, plant feedstuffs with fish oil and supplement. The diets containing the fish oil were fed up to either 49 days or 28 days before slaughter. The dietary treatments had no significant effects on growth performance, carcass characteristics and meat quality. When fish oil was included in the diet, higher levels of EPA, DPA and DHA were measured in the subcutaneous fat (up to 3.74%).     

Effects of genotype, level of supplementation, and organic chromium on growth performance, carcass, and meat traits grazing lambs

The aim of the present study was to evaluate the effects of Suffolk×Dorper (SD) and Rambouillet (R) lamb genotypes, dietary supplementation, and organic chromium on growth performance, carcass, and meat traits in male lambs grazing ryegrass pasture. SD lambs had heavier cold carcass (HCW) and better carcass yield (CY) and rib eye area at 12th rib (RA) than R lambs; R had larger legs. Feed supplement increased average daily weight gain (ADG), slaughter live weight (SLW), hot carcass weight (HCW) and cold carcass weight (CCW), carcass yield, carcass length (CL), leg perimeter (LP), major thorax width (MTW), minor thorax width (MiTW), rib eye area and dorsal fat at 12th rib (DF12), and also decreased meat moisture. Organic chromium reduced dorsal fat at 12th rib and meat fat content.     

Effect of pre-slaughter management regarding transportation and time in lairage on certain stress parameters, carcass and meat quality characteristics in Kivircik lambs

Thirty Kivircik lambs were used to investigate effect of pre-slaughter treatment on certain haematological and biochemical parameters, carcass and meat quality characteristics. Lambs were divided into three treatments: 75 min transport and lairage for 18 h (TS-L18 h); 75 min transport and lairage for 30 min (TS-L30 min) and no pre-slaughter transport and lairage for 30 min (NTS). Treatment, as a main effect, did not influence haematological and biochemical parameters, but sampling time significantly affected these parameters, except total protein. Plasma cortisol concentration at exsanguination in TS-18 h, TS-30 min and NTS treatments were 117.34, 119.23 and 72.51 ng/ml, respectively. pH of longissimus dorsi muscle was higher in TS-L30 min than other treatments. TS-L30 min lambs had the highest shear force value, the lowest WHC and cooking loss. TS-L30 min treatment yielded the darkest meat immediately after cutting and 1 h later. Meat redness, yellowness and chroma values were similar in treatments.     

The impact of new generation pre-dressing medium-voltage electrical stimulation on tenderness and colour stability in lamb meat

Previous work identified that a large number of domestic lamb carcases processed in Australia do not meet the recommended pH/temperature window during chilling. New medium voltage electrical stimulation technology has been developed to alleviate this problem. This study used an optimised setting (800mA with a pulse width 0.5ms) to evaluate the effects on meat quality with a focus on tenderness and meat colour. In total 40 (electrically stimulated) and 40 (non electrically stimulated) lambs from 11 lots killed over 2 days were evaluated. There was a significant difference (P<0.05) between stimulation treatments for initial pH, rate of pH decline and the predicted temperature at pH 6.0. There was also a large difference in the number of carcases that met the recommended window (pH of 6.0, between 18 and 25°C), with an average 67.5% of stimulated carcases and 25% of unstimulated carcases meeting or falling just above the recommended window. The stimulation treatment had no significant (P>0.05) effect on sarcomere length or myofibrillar fragmentation index (MFI) of the m. longissimus (LL). After 1day of ageing LL samples from stimulated carcases had a significantly lower (P<0.05) shear force than non stimulated samples, but there was no difference between stimulation treatments after 5 days ageing. However, ageing period did have a significant effect (P<0.001) on both MFI and shear force, such that 5days aged product had higher MFI and lower shear force values. There were minimal effects of stimulation on colour stability.     

The effect of heat stress on thyroid hormone response and meat quality in turkeys of two genetic lines

The current study evaluated the effect of heat stress on thyroid hormone (T(3) and T(4)) response and meat quality traits in two turkey lines: a growth-selected commercial line and a genetically unimproved control line. Birds were subjected to heat stress for different durations before harvest. Commercial line had higher pH(15min), and lightness values, but lower cook loss and marinade uptake than control line during the heat stress. There was no difference in drip loss between the two lines. The T(3) concentration was positively correlated with cook loss and was negatively correlated with marinade uptake. The thyroid hormone response during heat stress was less stable in the commercial line than in the control line and the unstable thyroid hormone response in commercial turkeys caused by heat exposure might influence the consistency of meat quality. Results of this study may provide an application in selecting turkeys which yield consistent meat quality.     

The effect of altered growth rates on the calpain proteolytic system and meat tenderness in cattle

The present study was conducted to determine the effects of growth pattern on the calpain system and meat tenderization. Twenty-four Friesian calves were randomly allocated to three treatment groups: FAST (fast growth rate), SLOW (severely restricted growth rate) and ALTER (restricted growth for 30 days followed by fast growth rate). Four animals from each group were slaughtered on day 32 or 45 after altering the growth rates. Samples of M. longissimus dorsi were rapidly frozen at slaughter for protein analysis by Western blotting. Restricted growth reduced the immunoreactivity of a calpastatin band (135 kDa) measured at 24 h postmortem. Immunoreactivity associated with the large subunit of μ- or m-calpain appeared to be unaffected by growth patterns. Shear force measurements taken after 14 days of conditioning were positively related to 135 kDa calpastatin at 24 h postmortem. In this study there was no clear relationship between shear force and growth pattern.     

The effect of ageing on changes in myofibrillar protein in selected muscles in relation to the tenderness of meat obtained from cross‐breed heifers

The aim of this study was to evaluate the impact of the ageing on changes in selected myofibrillar proteins and Warner–Bratzler shear force values in muscles from cross‐breed Charolaise × Holstein Friesian heifers. Triceps brachii (TB), infraspinatus (IS), vastus lateralis (VL), semimembranosus (SM), biceps femoris (BF) and semitendinous (ST) muscles after ageing were examined. A significant muscle effect was found in the case of basic chemical composition, Warner–Bratzler shear force values and cooking loss. The vastus lateralis characterised by the lowest intramuscular fat percentage (P ≤ 0.05). The highest connective tissue content was shown for infraspinatus. This muscle had the lowest Warner–Bratzler shear force values in every ageing time, regardless of the cooking method. Throughout the ageing process, selected myofibrillar proteins were altered in all examined muscles, but at varying rates. The SDS‐PAGE electrophoresis and Western blotting analysis showed that desmin and troponin‐T degradation affected both muscles and ageing effects (P ≤ 0.001).     

Relationship between muscle antioxidant status, forms of iron, polyunsaturated fatty acids and functionality (retail colour) of meat in lambs

The relationship between muscle vitamin E, forms of iron, polyunsaturated fatty acids (PUFA) and the redness of meat (retail display) at days 3 to 4 post slaughter from lambs offered 2 different diets was examined. Meat redness was positively related to vitamin E and heme iron and negatively related to total n-3, total n-6 and total PUFA content. However, after adjusting for the effects of vitamin E and heme iron content, there was no indication of any residual relationship between redness at days 3-4 of retail display and total n-3, total n-6 or total PUFA. This indicates that the relationship between PUFA and redness in meat is mediated through the effects of heme iron and vitamin E in the muscle. It appears that the level of highly oxidisable PUFAs in muscle tissues do not play a major role in maintenance of redness at days 3-4 of retail display, but the level of vitamin E and heme iron content are important.     

Effect of stocking density and group size on growth performance,carcass traits and meat quality of outdoor-reared rabbits

The effect of stocking density (16 rabbits/m², 5 rabbits/m², 2.5 rabbits/m², n = 60, Experiment 1) and group size (4 rabbits/cage, 8 rabbits/cage, 16 rabbits/cage, n = 88, Experiment 2) on productive performance, carcass and meat quality of a slow-growing rabbit population reared outdoors was investigated in two experiments. The highest stocking density induced the highest skin percentage. Lower stocking densities showed lower lightness of Biceps femoris and higher redness of Longissimus lumborum muscles. Four rabbits/cage group (Experiment 2) showed the highest daily weight gain and slaughter weight and the lowest skin percentage. The muscles of 16 rabbits/cage showed significantly higher pHu than 8 and 4 rabbits/cage. BF of 16 and 4 rabbits/cage showed higher L* value. Productive performance and meat quality of rabbits reared outdoors improved in low group size while stocking density needs more experiments. The best combination of density, group size and total available surface that showed the best production and carcass traits was of 5 rabbits/m², 4 rabbits/cage, and 0.8 m².     

The effects of a beta-agonist treatment, vitamin D3 supplementation and electrical stimulation on meat quality of feedlot steers

In this study, 20 young steers received no beta-agonist (C), 100 animals all received zilpaterol hydrochloride (Z), with 1 group only receiving Z while the other 4 groups received zilpaterol and vitamin D3 at the following levels (IU/animal/day) and durations before slaughter: 7 million for 3 days (3D7M); 7 million for 6 days (6D7M); 7 million for 6 days with 7 days no supplementation (6D7M7N) and 1 million for 9 days (9D1M). Left carcass sides were electrically stimulated (ES) and the right side not stimulated (NES). Samples were aged for 3 or 14 days post mortem. Parameters included Warner-Bratzler shear force (WBSF), myofibril filament length, sarcomere length and calpastatin and calpain enzyme activity. Both ES and prolonged aging reduced WBSF (P<0.001). 6D7M, 6D7M7N and Z remained significantly tougher than C (P<0.001), while 3D7M and 9D1M improved WBSF under NES conditions. ES is more effective to alleviate beta-agonist induced toughness than high vitamin D3 supplements.