Dietary vitamin E effect on color stability and sensory assessment of spoilage in three beef muscles

Effects of dietary vitamin E supplementation (1204 IU/head/day) for 122 days on color stability and microbial load on beef m. longissimus lumborum (LL), m. gluteus medius (GM) and m. psoas major (PM) were studied by subjective and objective evaluation. Color stability of these muscles followed the order LL > GM > PM (p < 0.05). Vitamin E-treated LL, GM and PM showed less metmyoglobin formation, higher a^* values and lower hue angle values than controls during storage at 4 °C (p < 0.05). Sensory evaluation demonstrated that panelists preferred the appearance of vitamin E-treated LL, GM and PM beef steaks. Vitamin E supplementation did not affect total microbial load on LL, PM and GM and did not influence panelists' olfactory assessment of microbial spoilage of beef. Endogenous -tocopherol concentration and lipid stability of microsomal fractions of LL, GM and PM were greater (p < 0.05) in vitamin E-treated muscles relative to controls. There was no muscle effect on the pro-oxidant activity of microsomes towards oxymyoglobin oxidation (p > 0.05). Oxymyoglobin stability was greater in the presence of microsomal fractions obtained from vitamin E-treated muscle than in those from controls. Dietary vitamin E supplementation delayed oxymyoglobin oxidation in LL, PM and GM muscle and increased the color shelf-life of these muscles without affecting total microbial load.     

The relationship between muscularity, muscle:bone ratio and cut dimensions in male and female lamb carcasses and the measurement of muscularity using image analysis

Dorsal images of 57 whole lamb carcasses (mean 22.5 kg, SD 2.3 kg) were obtained on a slaughter chain using a video camera. The lambs represented two sexes (29 cryptorchids, 28 ewes) and one genotype (Poll Dorset × Border Leicester × Merino). Cryptorchid carcasses were significantly (P < 0.05) leaner than ewe carcasses at a common weight but there was little difference in dimensional measurements of M. longissimus thoracis et lumborum (LL). The cryptorchid carcasses had a significantly better conformation (based on the EUROP system) even when adjusted to the same carcass weight and subcutaneous fat level.

From the hindleg and chump the following muscles were dissected and weighed: M. semimembranosus, M. adductor femoris, M. semitendinosus, M. biceps femoris, and M. quadriceps femoris. The femur was weighed, the length measured and a muscularity value calculated as described by Purchas et al. (1991 Meat Sci., 30, 181). There was no significant effect of sex on muscularity or muscle to bone ratio (M:B). Cryptorchid carcasses produced heavier (P < 0.05) round and midloin cuts but lighter (P < 0.05) chump and ribloin cuts. Overall there was no significant sex effect on the yield of hindquarter cuts.

Correlation showed a significant (P < 0.001) association between LL area and muscularity, with a lower correlation between round and topside cross-sectional area and muscularity. Neither muscle cross-sectional area nor muscularity was significantly related to M:B ratios. Muscularity increased with increasing carcass weight (P < 0.001) but M:B did not.

Prediction of muscularity was significantly (P < 0.05) improved by adding to hot carcass weight a measure of the combined width across the hind legs at interval three, as taken from video images, there being five equally-spaced intervals from the groin to the gambrel. A similar result was achieved by using carcass width at the third interval of five-eventy spaced intervals between the minimum shoulder width and the point of maximum loin width. There was no significant (P > 0.05) effect of sex on the relationships. It is concluded that muscularity could be used to indicate carcasses that have cuts with greater cross-sectional areas and that a video image analysis approach could potentially be used to derive an estimate of muscularity. The value to the meat marketing chain of identifying carcasses with large crosssectional areas remains to be established.     

Effect of clenbuterol on productive performance, body composition and muscle biochemistry in the rabbit

Twenty New Zealand White rabbits (INRA 1077 strain) were given a complete and balanced diet including a clenbuterol additive (100 μg per day) between 70 and 98 days. They were compared with 20 control rabbits. The treatment improved the growth performance (29.90 vs 26.07 g/day), the feed conversion (5.45 vs 6.46 g feed per g gain) and the carcass yield (64.37 vs 61.11%), by decreasing the relative weights of the skin and the digestive tract. Moreover, all organs in which development is precocious, were found to be relatively lighter. The muscle/bone ratio of the carcass was improved (7.56 vs 6.38), resulting in a greater relative development of muscle tissue, without any change in bone tissue weight. Perirenal and interscapular fat percentages in the carcass were reduced (3.23 vs 3.83 and 0.68 vs 0.86, respectively). Clenbuterol, a repartitioning agent, had therefore modified the growth allometry of the organs and tissues. In the hindleg region (Biceps femoris, Tensor fasciae latae, Semimembranosus accessorius), the ultimate muscular pH was increased, (+0.31 pH units on average), while the cooking loss was reduced (24.23 vs 24.88%). In the m. longissimus lumborum, the increase of ultimate pH (+0.31 units of pH), under the effect of clenbuterol, was explained by a relative increase in the oxidative metabolic pathway represented by aldolase/ICDH ratio (246 vs 284) and by a decrease in glucidic content (total glycosyl residues) of muscle (16.6 vs 26.2 μmol/g). Due to its effects on muscular biology, clenbuterol is thus likely to cause a change in meat quality.     

The kinetics of cooked meat haemoprotein formation in meat and model systems

The rate of cooked meat haemoprotein formation (measured as the rate of loss of myoglobin solubility) was found, at least initially, to obey first order kinetics in meat, aqueous muscle extracts and mixtures of myoglobin and bovine serum albumin. In meat at 60 °C the rate was dependent on the species, (the pigment was formed significantly faster in lamb m. longissimus dorsi than in beef m. longissimus dorsi) and anatomical location (cooked meat haemoprotein was formed in beef m. 1. dorsi about twice as rapidly as in both beef shin and chuck (shoulder) muscle of similar pH). The rate of formation was similar in aqueous muscle extracts to that found in meat and in these systems increased with decreasing pH. The activation energies for all beef systems studied were similar and typical of those associated with protein denaturation (˜300 KJ mol⁻¹); however, that from lamb appeared to be lower (˜200 KJ mol⁻¹). The problems of using colour as an index of temperature reached, either for microbial safety (E. Coli 0157:H7 destruction) or quality are discussed in the light of these results.     

The effect of stocking density in transit on the carcass quality and welfare of slaughter pigs: 1. Carcass measurements

In a trial involving 2496 pigs, the effect of transport stocking densities of 201, 241, 281 and 321 kg m⁻² on carcass quality and welfare were evaluated. This range encompassed the upper level set for 100 kg pigs in European Union legislation (235 kg m⁻²). Four farms and two lorries were involved over 16 experimental days with an average journey time of 3 hr. Stocking density had no effect on any variables measured. Source farm had a significant effect on ultimate pH, reflectance and electrical conductivity in the m. longissimus dorsi, reflectance in the m. adductor and extent of rigor mortis development in the m. semimembranosus. Overall, the measurements made produced no evidence that transport stocking density had an effect on the carcass quality or welfare of 95 kg pigs on short journeys.     

Variation in post-mortem rate of glycolyis does not necessarily affect drip loss of non-stimulated veal

In this study the effect of the rate of post mortem pH fall on the water-holding capacity of meat from moderately chilled veal carcasses was investigated. Also the relationship between muscle protein denaturation and drip loss of veal was examined. Three groups of 10 Friesian Holstein male veal calves each were selected on the basis of their pH in M. longissimus thoracis et lumborum (LTL) at 3 hr post mortem (pH₃): (1) fast pH-fall, pH₃ < 6.2; (2) intermediate pH-fall, 6.5 < pH₃ < 6.6; (3) slow pH-fall, pH₃ > 6.7. After 48 hr of chilling the LTL was excised from the carcass and sampled for determination of drip loss, filter paper wetness, sarcomere length, protein solubility and transmission value. Differences in pH₃ were not associated with differences in drip loss, filter paper wetness or differences in protein denaturation. It is suggested that at the relatively high veal carcass chilling rate the effect of rate of pH-fall on protein denaturation and thus on drip loss is negligible. Drip loss of veal was highly correlated with both solubility of sarcoplasmic (r = −0.67; p < 0.001) and total muscle protein (r = −0.54; p < 0.01) and with transmission values (r = 0.66; p < 0.001). These results indicate that protein denaturation measurements may be a good predictor for drip loss of veal.     

Differences in composition, muscularity, muscle:bone ratio and cut dimensions between six lamb genotypes

Carcass measurements and composition data were obtained for 198 lambs representing two sexes (104 cryptorchids, 94 ewes). Dorsal images of 166 of the carcasses were obtained on the slaughter chain using a video camera. The lambs were sired by a selection of Poll Dorset (PD), Texel (T), Border Leicester (BL) and Merino (M) rams, born to Border Leicester × Merino (BLM) and Merino (M) ewes giving 6 genotypes (PD × BLM, T × BLM, PD × M, T × M, BL × M, M × M). From the right hindleg and chump, the following muscles were dissected and weighed: semimembranosus, adductor femoris, semitendinosus, biceps femoris, and quadriceps femoris. The femur was weighed, the length measured and a muscularity value calculated as described by Purchas, et al. (1991, Meat Sci., 30, 181).

Merino cryptorchid lambs were significantly (P < 0.05) leaner, as measured by GR tissue depth (for explanation, see MATERIALS AND METHODS) adjusted to a mean carcass weight of 24.2 kg, than BL × M lambs, but there was no difference between genotypes within the ewe group (mean carcass weight of 17.1 kg). Genotype differences were found for conformation using the EUROP scoring system. Merino lambs had a greater proportion (P < 0.001) of poorer scores, particularly compared to PD × BLM and T × BLM carcasses. The BL × M carcasses had a significantly (P < 0.05) smaller m. longissimus thoracis et lumborum area than other genotypes with no difference between carcasses of T and PD sires.

Muscularity values for the BL × M and M lambs were significantly (P < 0.05) lower than the other crosses but not different from each other. Carcasses from T sires had significantly (P < 0.05) higher muscularity values than those from PD sires. A negative association (r = −0.56) was found between EUROP scores and muscularity when carcass differences were adjusted for, but significant differences between genotypes for muscularity were not necessarily carried through to differences in EUROP conformation score. BL × M carcasses had the lowest muscle:bone ratio and T × M the highest with M carcasses having similar ratios to carcasses from PD-sired lambs. Only small differences were found between genotypes for composition of the hindleg, the exception being BL × M carcasses of both sexes which were significantly (P < 0.05) fatter than T × BLM, T × M and PD × M carcasses. Carcasses from T sires had significantly (P < 0.05) more muscle in the hindleg than carcasses from PD sires, with the differences being greater in the heavier cryptorchids (1.8%) than the ewes (1.1%). There was no consistent effect of genotype on the cross-sectional areas of the round and topside cuts within either sex.

Differences between genotypes for the proportion of the carcass attributed to the round were small and only for BL × M ewe carcasses was this cut significantly lighter (P < 0.05) than from all other genotypes, except the PD × BLM carcasses. This trend was similar for the topside and silverside cuts. A moderate correlation (r = 0.46; P < 0.001) was found between muscularity values determined by dissection and those predicted using the equations of Hopkins et al. (1996, Proc. Aust. Soc. Anim. Prod., 21, 181) based on carcass width measurements taken from video images.     

Diverse lamb genotypes-2. Meat pH, colour and tenderness

The effect of genotype on meat ultimate pH, colour and tenderness was studied in 3 experiments involving 436 lambs. The lambs were sired by a selection of Texel (T), Poll Dorset (PD), Border Leicester (BL) and Merino (M) rams, crossed with Border Leicester × Merino (BLM) and Merino (M) ewes giving 6 genotypes (T × BLM, PD × BLM, T × M, PD × M, BLM and M × M). In experiment 1, pH data were obtained for 4 muscles (M. Semimembranosus (SM), M. Biceps femoris M. Semitendinosus and M. Longissimius thoracis et lumborum (LL)) from 198 carcasses representing two sexes (104 cryptorchid males, 94 ewes). There were significant differences for pH between genotypes in both sex groups. BL × M and M × M lambs tended to have higher pH values than the other genotypes.

In experiment 2, meat pH, colour using a chromameter, and tenderness data were obtained for 186 lambs representing two sexes (101 cryptorchid males, 85 ewes). There were few significant differences between genotypes for the various meat quality traits amongst the ewes. The PD × BLM ewes had a significantly lower (p < 0.05) pH than the BL × M ewes for the LL and SM muscles.

The BL × M crypt orchids had a higher LL muscle pH (p < 0.05) than the PD × BLM cryptorchids with other genotypes being intermediate. There were no significant differences between the genotypes for muscle shear force values. Within experiment 2, LL samples were taken from an additional 52 cryptorchid carcasses these being from 3 specific Poll Dorset sires (experiment 3). One of these sires (sire 3) was suspected of carrying a gene for increased muscling. Sire had a significant effect (p < 0.05) on shear force values, cooking loss and L^* colour values, but not a^* or b^* colour values or pH. Sire 3 progeny had significantly (p < 0.001) tougher LL muscles than those from the other 2 sires. Sire 3 also had the lowest L^* values, but was intermediate for cooking loss. There was no significant sire effect on LL area at the same carcass weight, but boneless loins from the progeny of Sire 3 were significantly (p < 0.05) heavier.

In a fourth experiment, meat colour was measured at three sites (LL, diaphragm and M. Obliquus externus abdominis) on 86 cryptorchid carcasses 24 hr post-mortem. There was little association between L^*, a^* and b^* values measured at the different sites.     

Diverse lamb genotypes-1. Yield of saleable cuts and meat in the carcass and the prediction of yield

Carcass measurements and composition data were obtained for 591 lambs representing two sexes (307 cryptorchid males, 284 ewes). The lambs were sired by a selection of Texel (T), Poll Dorset (PD), Border Leicester (BL) and Merino (M) rams, crossed with Border Leicester × Merino (BLM) and Merino (M) ewes giving 6 genotypes (T × ELM, PD × BLM, T × M, PD × M, BL × M, M × M). m × M carcasses were significantly (p < 0.05) leaner than all other genotypes as measured by GR at a common weight, except for ewe carcasses where they were not significantly leaner than T × M carcasses. There was no difference in GR between Texel and Poll Dorset sired carcasses. The BL × M and PD × BLM carcasses were the fattest at the 5th rib. M × M lambs produced the lightest carcasses in each sex. Genotype differences were found for conformation using the EUROP scoring system. M×M lambs had a greater proportion (p < 0.001) of poorer scores particularly compared to PD × BLM and T × BLM carcasses. Analysis of Texel and Poll Dorset sired carcasses showed that the Texel cross had a better conformation than Poll Dorset cross amongst both sexes. BLM dams produced carcasses with a superior conformation compared to Merino dams (p < 0.001) in both sexes. BL × M carcasses had a significantly (p < 0.05) smaller M. longissimus thoracis et lumborum area (LL area) than other genotypes, except for M × M ewe carcasses. Texel sired ewe carcasses had a larger LL area (p < 0.05) than those sired by Poll Dorsets, but there was no significant difference for the heavier cryptorchid carcasses. Saleable meat yield for the BL × M carcasses of both sexes was significantly less (p < 0.001) than all other genotypes. M × M carcasses of both sexes produced similar amounts of saleable product to second cross carcasses with the T × M carcasses being superior, resulting in a significant sire breed effect. Texel sired carcasses produced more product than Poll Dorset carcasses. Year had a significant (p < 0.05) effect on all carcass measures and saleable meat yield. Genotype had a significant (p < 0.05) effect on the proportion of each cut except for the neck from cryptorchids and neck fillet from ewes. Texel sired genotypes had significantly (p < 0.05) heavier weights for the hindleg and forequarter cuts than those sired by Poll Dorsets. For the BL × M and m × M genotypes, some of the hindleg cuts, such as the topside and silverside weighed less than other genotypes. The boneless loins from the Poll Dorset genotypes were the heaviest, resulting in a significant (p < 0.05) sire breed effect, with all other genotypes being similar. Models were developed to estimate the yield of cuts and saleable meat using hot carcass weight, GR and other variables. The amount of variation in yield explained by hot carcass weight and GR ranged from r² = 0.06 to 0.23. Inclusion of LL area increased the r² values up to 0.39. Inclusion of both genotype and year significantly (p < 0.05) improved the prediction of yield, with year contributing the most. The addition of sex had no effect on the prediction of yield.     

Variability within intramuscular fat content of pigs as measured by gravimetry, FTIR and NMR spectroscopy

In order to determine in vivo intramuscular fat content of pigs' biceps femoris, three methods were compared. Gravimetry and FTIR spectroscopy after total fat extraction from a biopsy (about 400 mg skeletal muscle tissue) and in vivo ¹H NMR spectroscopy after imaging and volume of interest selection were used. Mean values (g fat/100 g fresh tissue) were, respectively, 1·47 ± 0·35 (gravimetry), 1·26 ± 0·33 (FTIR) and 0·51 ± 0·19 (NMR); but NMR-values represented only triglycerides. Within an intramuscular fat range from 1·1 to 2·7 g per 100 g fresh muscle tissue, possible to estimate a calibration line between the in vitro and in vivo data for hybrid piglets of about 18 kg. Repeated in vivo NMR measurements on the same muscle volume showed a mean coefficient of variation of 5·5 ± 2·7%. The coefficient of variation of measurements on different volumes within the same muscle was 14 ± 10%. The mean intramuscular fat content of 18 kg or 100 kg pigs was, respectively, 1·64 ± 0·46 (biceps femoris) and 1·32 ± 0·1 (longissimus dorsi) g per 100 g fresh muscle tissue.     

The influence of porcine growth hormone on muscle fibre characteristics, metabolic potential and meat quality

Treatment of lean female pigs with porcine growth hormone (placebo or 80 μg pGH per kg body weight per day) for 6 weeks from 50 kg to 86 kg body weight did not change the frequency and the percentage area of muscle fibre types (ST, FTa and FTb fibres) and muscle capillarity of M. longissimus dorsi, M. gluteus medius and M. psoas major. The mean fibre cross-sectional area increased 5·3%, albeit nonsignificantly, corresponding to a 6·6% increase in carcass meat. The muscles contained slightly less dry matter and protein, and the lipid content of M. longissimus dorsi decreased 19% after pGH treatment. In the backfat the fatty acid composition changed towards a higher ratio of polyunsaturated to saturated fatty acids. The pH_u of M. longissimus dorsi was unaltered, while the pH₄₅ was reduced by pGH. The muscle glycogen level and the activity of lactate dehydrogenase (LDH), citrate synthetase (CS), and 3-OH-acyl-CoA-dehydrogenase (HAD) of M. longissimus dorsi were unchanged by pGH. The haem pigment, shear force, sarcomere length and eating quality of loin chops, were unaffected by pGH treatment. The results show that pGH treatment did not change the muscle characteristics in a way that affects the meat quality of M. longissimus dorsi in lean female pigs.     

屠宰日龄对伊拉兔胴体和肉质量的影响

对伊拉兔在60、70、80 日龄屠宰的胴体和肉质量进行比较研究,结果表明：宰前活质量、热胴体质量、冷却胴体质量、参考胴体质量、屠宰率、肾周脂肪质量/参考胴体质量、可解剖脂肪质量/参考胴体质量均随日龄的增加而明显增大（P＜0.05）;胴体的滴水损失随日龄增大而明显减少（P＜0.05）;pH24 h值随日龄增加有下降趋势;股二头肌L*、a*值在70 日龄和80 日龄组间无显著差异（P＞0.05）,背最长肌L*、a*值在各日龄组间无显著差异（P＞0.05）;背最长肌系水力和剪切力在70 日龄和80 日龄组间无显著差异（P＞0.05）,且均大于60 日龄;背最长肌的蒸煮损失随日龄增加而明显减小（P＜0.05）;背最长肌和后腿肌的粗蛋白、粗灰分含量在各日龄组间无显著差异（P＞0.05）,粗脂肪含量随日龄增大而明显增加（P＜0.05）,而水分含量有一定减小。伊拉兔在60 日龄屠宰生长潜力未充分发挥,70 日龄屠宰效益好,80 日龄屠宰改善了胴体和肉的品质。     

Effect of muscle-type, stage of maturity and level of nutrition on the quality of meat from male buffalo calves

The effect of stage of maturity (8, 12 and 16 months), level of nutrition (100, 115 and 130% of both energy and protein) and muscle type, on the quality of selected muscles viz. longissimus dorsi (LD), biceps femoris (BF), triceps brachii (TB) and semi tendinosus (ST) from male buffalo calves was evaluated. The LD muscle gave higher values for pH, acidity and glycogen contents while ST gave higher values for cook release volume (CRV) and Warner Bratzler shear force. The TB muscle had higher expressible juice content (EJC). The 16 month old calves gave significantly higher values for the various parameters as compared to 8 and 12 month ones except EJC and CRV. A significant increase (P 0.05) in pH, EJC and shear force values was observed with increase in level of nutrition. The shear force values which are an indicator of toughness/tenderness increased with the stage of maturity. The 8–12 month old male buffalo calves reared on 130% level of nutrition had the best fresh meat quality (P 0.05) indicated by the various parameters evaluated.     

The effect of production system and age on levels of iron, taurine, carnosine, coenzyme Q(10), and creatine in beef muscles and liver

Samples of longissimus (LL) and triceps brachii (TB) muscles from Angus-cross heifers finished either on a high-concentrate ration in Washington, USA, (US cattle, n = 15) or on pasture in New Zealand (NZ cattle, n = 16) were assessed for composition characteristics. Half of the NZ cattle were of a similar age to the US cattle (NZAge) and half were of a similar weight (NZWt). Iron concentration was higher in TB (20.9 vs. 17.5 μg g⁻¹; P < 0.001) and was higher for the NZWt group than the NZAge group or the US cattle. The proportion of iron as haem iron was highest for the NZWt group (87.3%; P < 0.01), but the proportion as soluble haem iron was highest for the US cattle. For a sub-group of 10 pasture-finished cattle, iron levels in cheek muscle were higher than for LL or TB, and liver levels were 66% higher than cheek muscle. The proportion of haem iron, however, was lowest in liver (55.3%) and was lower in cheek muscle (78.4%) than LL or TB. Relative to LL, TB had higher levels of taurine and coenzyme Q₁₀, but lower levels of carnosine, creatine and creatinine, as expected for a muscle with a more aerobic metabolism. These differences were magnified for the even more aerobic cheek muscle. Differences between the two NZ groups were small, but muscles from the US cattle contained less taurine, carnosine, coenzyme Q₁₀, and creatinine. Reasons for these differences in various meat components for similar cattle from different production systems are not clear.     

Effects of halothane genotype and pre-slaughter treatment on pig meat quality. Part 1. Post mortem metabolism, meat quality indicators and sensory traits of m. Longissimus lumborum

Forty-eight castrated F₂ offspring of Piétrain and Large White pigs were allocated to a 3 × 2 factorial design in order to study the interactive effect of halothane genotype (NN, Nn and nn) and pre-slaughter treatment [referred to as ‘Experimental’ (EXP) and ‘Commercial-like’ (COL) conditions; the latter combining short transportation, mixing unfamiliar pigs and slaughtering shortly after transport] on muscle post mortem changes and meat quality. The pigs were slaughtered over 4 days. Pre-slaughter glycogen depletion in M. longissimus lumborum (LL) was greater in the nn pigs, compared with the two other genotypes. Lactate accumulation post mortem in LL muscle was greater and the pH value at 40 min post mortem was lower in nn compared with NN pigs. Nn pigs were close to nn pigs for lactate accumulation and showed intermediate pH values in the LL muscle. In the M. semimembranosus (SM), NN and Nn pigs showed the same rate of post mortem changes, as evidenced by similar glycogen, lactate, creatine phosphate and ATP levels, and pH values at 40 min post mortem. Pre-slaughter treatment did not affect the rate of post mortem changes in both muscles and no interactive effect with halothane genotype was found. The pigs slaughtered under the ‘COL’ conditions had a significantly higher ultimate pH in the LL and SM muscles than those slaughtered under the ‘EXP’ conditions. The LL muscle from nn pigs was paler (higher L*) than that of NN and Nn pigs. In SM muscle, Nn pigs showed a significantly higher L* value than NN pigs. Drip loss of the LL muscle was significantly higher in nn compared with NN pigs, the heterozygous pigs being intermediate. Sensory evaluation of the LL muscle showed that nn pigs had a lower colour intensity and colour homogeneity of raw meat than NN and Nn pigs. Tenderness was significantly lower in nn compared with NN pigs, the Nn pigs being intermediate. Pre-slaughter treatment significantly increased ultimate pH in both muscles (LL and SM) but did not affect significantly the rate of pH fall (pH₄₀). It did not affect any of the meat quality traits and no interactive effect with halothane genotype was found. These results confirmed the influence of the halothane gene on the kinetics of muscle post mortem changes and related meat quality traits. They also confirmed the intermediate position of heterozygous pigs in terms of meat quality.     

The effect of production system and age on concentrations of fatty acids in intramuscular fat of the longissimus and triceps brachii muscles of Angus-cross heifers

The concentrations of fatty acids were measured in intramuscular fat from the longissimus lumborum (LL) and triceps brachii (TB) muscles of Angus-cross heifers finished either on a high-concentrate ration in Washington, USA, (US cattle, n = 15) or on pasture in New Zealand (NZ cattle, n = 16). Half of the NZ cattle were of a similar age to the US cattle (NZAge) and half were of a similar weight (NZWt). Intramuscular fat levels were higher for the LL muscle and for the US cattle but only within the LL muscle (P < 0.05). Aspects of the fatty-acid patterns that are of relevance to human nutrition tended to favour the pasture-finished NZ cattle with lower n − 6/n − 3 fatty acid ratios (P < 0.001), higher concentrations of an anticarcinogenic conjugated linoleic acid (C18:2 c9,t11) (P < 0.05) and its precursor (trans-vaccenic acid, TVA) (P < 0.01), and lower levels of the 18-carbon trans monounsaturated fatty acids other than TVA (P < 0.01). Concentrations of 20 of the 22 fatty acids analysed differed significantly between the two muscles. When values were adjusted to a common intramuscular fat level by covariance, most of the group differences remained, but a number of the muscle differences became non-significant. For almost half the fatty acids considered, there was a significant interaction between treatment group and muscle, which indicates that the results for one muscle do not necessarily apply to other muscles, although the ranking of the groups was usually the same for both muscles.     

Crossbreeding dual-purpose cattle for beef production in tropical regions

Six breed types groups of six steer calves each were used to observe differences in growth and carcass traits: F1 Brown Swiss (F1BS), F1 Holstein (F1HO), F2 Brahman (F2BR), F2 Criollo Rio Limon (F2CRL), purebred Criollo Rio Limon (CRL), and Perija Mosaic (PMO). After 404 days of grazing, the heaviest F1BS and F2BR steers were different from F1HO and CRL counterparts (p < 0.05) in slaughter weight. F2BR dressed higher and had better muscle conformation scores than F1BS, F1HO, F2CRL and CRL (p < 0.05). F1BS had the thickest backfat (0.5 cm) but only differed (p < 0.05) from F1HO (0.3 cm). Rib eye area, marbling score, carcass maturity, quality or yield grade, boneless cut percentages, bone percentage or percent trimmable fat did not vary among breed types. All steers were within the A maturity level and graded Standard. Results indicate the importance of feeding dual-purpose steers to heavier weights to please industry preferences.     

Carcass traits, muscle characteristics, and palatability attributes of lambs expressing the callipyge phenotype

Dorset×Suffolk crossbred wethers expressing a normal phenotype (normal, n=10) and callipyge phenotype (CLPG, n=9) were fed individually and slaughtered upon reaching maximum growth potential. Carcass weight did not differ (P>0.05), but fat thickness was lower (0.30 vs. 0.56 cm), ribeye area was greater (24.4 vs. 16.6 cm²), and USDA yield grade was improved (1.6 vs. 2.6) for CLPG carcasses (P < 0.05). Carcasses from CLPG demonstrated higher cutability and a more desirable muscle to bone ratio, with less fat and more lean as a percentage of total side weight (P<0.05). Biceps femoris (BF), semitendinosus (ST), semimembranosus (SM), longissimus thoracis et lumborum (LTL), and triceps brachii (TB) were used to compare muscle characteristics of both phenotypes. Muscle from normal lambs had lower calpastatin activity, higher fat percentages and lower moisture percentages (P<0.05). Total amount and solubility of collagen were not affected by phenotype nor was sarcomere length. Shear force and trained sensory attributes were evaluated for BF and LTL only. Shear force values did not differ between normal and CLPG BF while CLPG LTL had higher (P< 0.05) shear force values than normal LTL. Biceps femoris did not differ between phenotypes in trained sensory panel ratings. However, CLPG LTL received the lowest sensory ratings for connective tissue amount and myofibrillar and overall tenderness (6.11, 4.97, and 4.95, respectively) and the normal LTL received the highest ratings (P < 0.05; 7.10, 7.00, and 6.90, respectively). The CLPG phenotype had a positive influence on carcass characteristics but had a negative influence on tenderness of some muscles, possibly through the myofibrillar component of the muscle.     

Post-mortem variation in pH, temperature, and colour profiles of veal carcasses in relation to breed, blood haemoglobin content, and carcass characteristics

A total of 1764 male calves of the Meuse-Rhine-Yssel (MRY) and Friesian-Holstein (FH) breeds were slaughtered at two commercial slaughterhouses to investigate the variation in pH, temperature, and colour of Dutch veal carcasses processed without electrical stimulation and with a moderate chilling regimen (average temperature of the longissimus lumborum muscle at 45 min, 3, 24, and 48 h post-mortem was 38.4, 23.3, 3.7 and 1.9°C, respectively). Blood haemoglobin content was determined 2 weeks before slaughter. The efficacy of captive bolt stunning was scored and the carcass movements after shackling registered. Temperature and pH measurements were carried out at 45 min, and 3, 24, and 48 h after slaughter in the longissimus lumborum muscle (LL). Muscle surface colour (CieLAB-values) was measured with a colorimeter at the rectus abdominis muscle at the same times post-mortem. Carcass conformation and visual carcass colour classification were determined at 45 min post-mortem. Carcasses with a better EUROP-conformation score and heavier weight showed a higher rate of pH decline and a slower cooling rate. Slight differences in cooling systems between the slaughterhouses caused marked differences in pH and temperature profiles. Significant differences in carcass weight were observed between the MRY and FH breeds, leading to significant differences in pH and temperature profiles. Carcass colour of the two breeds was similar. Veal carcass colour in general was not related to the observed variation in post-mortem pH and temperature in the longissimus lumborum muscle and was shown to be more associated with the blood haemoglobin content. Haemoglobin content of the blood in the period before slaughter was shown to be related to the visually assessed carcass colour at 45 min post-mortem (using a 10-colour scale), as well as to the instrumentally determined L*-value, with significant correlation coefficients of 0.61 and -0.61, respectively. Repeated captive bolt stunning to obtain unconsciousness significantly decreased pH at 3 h post-mortem. The degree of carcass movement after slaughter did not influence pH, temperature, or colour profiles of the carcasses.