Production and processing studies on calpain-system gene markers for tenderness in Brahman cattle: 2. Objective meat quality

Effects and interactions of calpain-system tenderness gene markers on objective meat quality traits of Brahman (Bos indicus) cattle were quantified within 2 concurrent experiments at different locations. Cattle were selected for study from commercial and research herds at weaning based on their genotype for cal-pastatin (CAST) and calpain 3 (GAPN3) gene markers for beef tenderness. Gene marker status for i-calpain (CAPN1-4751 and CAPN1-316) was also determined for inclusion in statistical analyses. Eighty-two heifer and 82 castrated male cattle with 0 or 2 favorable alleles for CAST and CAPN3 were studied in New South Wales (NSW), and 143 castrated male cattle with 0, 1, or 2 favorable alleles for CAST and CAPN3 were studied in Western Australia (WA). The cattle were backgrounded for 6 to 8 mo and grain-fed for 117 d (NSW) or 80 d (WA) before slaughter. One-half the cattle in each experiment were implanted with a hormonal growth promotant during feedlotting. One side of each carcass was suspended from the Achilles tendon (AT) and the other from the pelvis (tenderstretch). The M. longissimus lumborum from both sides and the M. semitendinosus from the AT side were collected; then samples of each were aged at 1°C for 1 or 7 d. Favorable alleles for one or more markers reduced shear force, with little effect on other meat quality traits. The size of effects of individual markers varied with site, muscle, method of carcass suspension, and aging period. Individual marker effects were additive as evident in cattle with 4 favorable alleles for CAST and CAPN3 markers, which had shear force reductions of 12.2 N (P 0.05) of interactions between the gene markers, or between the hormonal growth promotant and gene markers for any meat quality traits. This study provides further evidence that selection based on the CAST or CAPN3 gene markers improves meat tenderness in Brahman cattle, with little if any detrimental effects on other meat quality traits. The CAPN1-4751 gene marker also improved beef tenderness without affecting other objective meat quality traits in heterozygous cattle compared with homozygotes for the unfavorable allele

Production and processing studies on calpain-system gene markers in cattle

Gene markers for tenderness have been shown to be related to shear force of meat from cattle (Barendse et al., 2008; Page el al., 2002; White el al., 2005). Four tenderness markers currently available commercially are based on polymorphisms in genes controlling components of the post-mortem tenderisation process, specifically the calpain proteolytic system. The objectives of this study were to quantify the magnitude of effects of tenderness gene markers on growth, feed efficiency, carcass characteristics and beef quality in Brahman cattle, and to quantify interactions within and between tenderness gene markers, gender, hormonal growth promotant, method of carcass hang, and major muscles

Cattle with more reactive temperaments have lower resting muscle glycogen

The objective of this experiment was to evaluate the effect of differences mammal temperament on muscle glycogen and lactate concentration. The temperament of 81 Angus steers was assessed seven times between weaning and yearling age using flight speed (m/s) and crush score (1 to 5) measurements . Muscle biopsy samples were collected four times from the semimembranosus (SM) and semitendinosus (ST) during the pasture finishing phase (around 18 to 24 months) and immediately after slaughter from each steer. Each biopsy was analysed for glycogen and lactate, and glycogen depletion due to pre-slaughter stress was calculated as the difference between on-farm glycogen and muscle glycogen at slaughter. An increase m flight speed from 0 .75 to 2.25 m/s was associated with a reduction in muscle glycogen concentration by 8 .9% (P<0 .05) and an increase in muscle lactate concentration by 17.3% (P<0.01) m both the SM and ST. An increase in crush score from 1.25 to 3 reduced muscle glycogen by I 0.4% (P<0.05) in the SM and ST and increased lactate in the ST by 42% (P<0 .05). Thus, animals with calm temperaments had higher resting glycogen concentration and mobilised less during stress compared to more excitable animals. However, the effect of temperament on glycogenolysis pre-slaughter or glycogen concentration at slaughter was not evident, most likely due to these animals becoming habituated to human contact. In conclusion it is likely that improved temperament will increase muscle glycogen concentration prior to slaughter and reduce the incidence of dark, firm, dry beef

A post-transcriptional mechanism regulates calpastatin expression in bovine skeletal muscle

The objective of this study was to investigate whether single nucleotide polymorphisms (SNP) in the calpain 1 (CAPN1), calpain 3 (CAPN3) and calpastatin (CAST) genes, which have been shown to be associated with shear force and tenderness differences in the skeletal muscle of cattle, contribute to phenotypic variation in muscle tenderness by modulating the transcriptional activity of their respective gene. The mRNA expression of the calpain and CAST genes was assessed in the longissimus lumborum muscle (LLM) of cattle from two herds located in distinct production zones on the east (New South Wales, NSW) and west (Western Australia, WA) of Australia. The cattle in the herds were mainly Brahman cattle (Bos indicus) with smaller populations of Angus cattle (Bos taurus). There were 191 steers in the WA herd and 107 steers and 106 heifers in the NSW herd. These herds were established by choosing cattle from the diverse population which had different single nucleotide polymorphism (SNP) genotypes at the CAPN1, CAPN3 and CAST loci. Using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), the transcriptional activities of the CAPN1 and the CAST genes, but not the CAPN3 gene, were found to differ between favorable, positively associated with tenderness, and unfavorable, negatively associated with tenderness, allelic variants of these genes. These findings suggest that the muscle shear force and consumer taste panel differences in tenderness explained by the CAPN1 and CAST gene markers are a consequence of alterations in their mRNA levels, which may ultimately influence the protein activity of these genes, thereby altering the rate and(or) the extent of postmortem proteolysis in skeletal muscle. Of particular importance were the significantly lower type II and type III CAST 5′ splice variant mRNA levels that were detected in the LLM muscle of Brahman and Angus cattle with 2 favourable alleles of the CAST:c.2832A > G polymorphism. Moreover, a reduction in the abundance of an alternative polyadenylated variant of the CAST transcript, terminated at the proximal polyadenylation site, provides a unique insight into the potential involvement of a post-transcriptional regulatory mechanism which may influence protein expression levels in bovine skeletal muscle

Qualitative Behavioural Assessment of Angus steers during pre-slaughter handling and relationship with temperament and physiological responses

This study examined the behavioural expression of cattle immediately prior to slaughter through the process of Qualitative Behavioural Assessment (QBA), and compared these results to measurements of physiology and temperament. Twenty-eight Angus steers were filmed while in a funnel chute as they were being moved towards an abattoir killing box. Footage of cattle was shown in random order to 15 observers. Observers assessed the cattle using a qualitative approach based on Free Choice Profiling (FCP) methodology, which gives observers complete freedom to choose their own descriptive terms. Data were analysed with Generalised Procrustes Analysis (GPA). There was significant consensus (P 5.7 (classified as a 'dark cutter') had a low value for GPA dimension 2 (scored as relatively more 'annoyed'/'frightened'). The findings from this study suggest that QBA could contribute to assessing pre-slaughter animal handling, highlighting potential issues to be followed up with additional measures. The significant correlations between GPA dimension 1 with slaughter order and plasma lactate warrant further investigation, comparing behavioural expression with aspects of meat quality

Molecular Value Predictions: Associations with beef tenderness in brahman cattle

Recently, panels of gene markers have become available that allow for Molecular Value Predictions (MVPs) that represent a molecular breeding value to be calculated for economically important traits (Anon. 2009). This study tested the hypothesis that Molecular Value Predictions (MVPs) generated for tenderness from a commercially available marker panel would have favourable associations with beef tenderness. It also tested the hypothesis that the MVPs for marbling and feed efficiency would not have unfavourable associations with beef tenderness. Two experiments, one in NSW and one in WA, designed to examine tenderness gene marker effects and interactions within Brahman cattle (Cafe et al. 2010), were used to test the above hypotheses

Molecular value predictions: Associations with beef quality, carcass, production, behavior, and efficiency phenotypes in Brahman cattle

Data from 2 previously published experiments, New South Wales (NSW; n = 161) and Western Australia (WA; n = 135), were used to test molecular value predictions (MVP), generated from commercially available gene markers, on economically important traits of Bos indicus (Brahman) cattle. Favorable tenderness MVP scores were associated with reduced shear force values of strip loin (LM) steaks aged 7 d from Achilles-hung carcasses (P ≤ 0.06), as well as steaks aged 1 (P ≤ 0.08) or 7 d (P ≤ 0.07) from carcasses hung from the pelvis (tenderstretch). Favorable tenderness MVP scores were also associated with improved consumer tenderness ratings for strip loin steaks aged 7 d and either Achilles hung (P ≤ 0.006) or tenderstretched (P ≤ 0.07). Similar results were observed in NSW for rump (top butt; gluteus medius) steaks, with favorable tenderness MVP scores associated with more tender (P = 0.006) and acceptable (P = 0.008) beef. Favorable marbling MVP scores were associated with improved (P ≤ 0.021) marbling scores and intramuscular fat (IMF) content in the NSW experiment, despite low variation in marbling in the Brahman cattle. For the WA experiment, however, there were no (P ≥ 0.71) relationships between marbling MVP and marbling scores or IMF content. Although residual (net) feed intake (RFI) was not associated (P = 0.63) with the RFI (feed efficiency) MVP, the RFI MVP was adversely associated with LM tenderness and acceptability of 7-d-aged Achilles-hung carcasses in NSW (P ≤ 0.031) and WA (P ≤ 0.037). Some other relationships and trends were noted between the MVP and the other traits, but few reached statistical significance, and none were evident in both experiments. Results from this study provide evidence to support the use of the tenderness MVP. The value of the marbling MVP, which was associated with marbling in only 1 herd, warrants further evaluation; however, there appears to be no evidence to support use of the RFI MVP in Brahman cattle

Production and processing studies on calpain-system gene markers for beef tenderness: Consumer assessments of eating quality

We investigated the effects of calpainsystem genetic markers on consumer beef quality ratings, including interactions of marker effects with hormonalgrowth promotant (HGP) use and tenderstretch hanging. Brahman cattle in New South Wales (NSW; n = 164) and Western Australia (WA; n = 141) were selectedat weaning from commercial and research herds to achieve balance and divergence in calpastatin (CAST) and calpain 3 (CAPN3) gene marker status. Genotypesfor μ-calpain (CAPN1-4751 and CAPN1-316) were also determined. Angus cattle (49 in NSW, 17 in WA) with favorable CAST and CAPN3 alleles, balanced for CAPN1-316 status, were also studied. Half the cattle at each site had HGP (Revalor-H, containing 200 mg trenbolone acetate and 20 mg 17β-estradiol) implants during grain finishing. One side of each carcass was suspended from the Achilles tendon (AT) and the other from the pelvis [tenderstretch (TS)]. Meat StandardsAustralia consumer panels scored 7-d aged striploin steaks from both AT and TS sides, and 7-d aged rump and oyster blade steaks from the AT side of each carcass. Two favorable CAST alleles increased tenderness ratings of AT-striploin, TS-striploin, rump, and oyster blade steaks by, respectively, 6.1, 4.2, 4.2, and 3.1 units, and overall liking by 4.7, 2.8, 2.9, 3.7 (all P < 0.04). Two favorable CAPN1-4751 alleles increased tenderness of AT-striploin, TS-striploin, and rump steaks by 6.5, 4.3, and 3.9 units, and overall liking by 5.6, 3.1, and 4.1 units. Two favorable CAPN3 alleles improved rump steaks by 3.7, 3.3, 3.7, and 3.5 units, for tenderness, juiciness, liking the flavor, and overall liking. There were no significant CAPN1-316 effects. The effect of HGP was greatestfor the AT-striploin (reducing tenderness and overall liking by 8.2 units, P < 0.001), then TS-striploin (-5.6 for tenderness, -5.0 for overall liking, P < 0.001), and then rump (-4.4 for tenderness, -3.3 for overall liking, P < 0.007). Processing conditions differed considerably between NSW and WA. Rump steaks from NSW scored about 10 units greater than those from WA, but Angus and Brahman steaks from the same location with the same marker alleles had similar scores. In contrast, NSW Angus striploin steaks scored about 15 units greater for tenderness and overall liking (P < 0.001) than cattlewith the same marker alleles at the other 3 location × breed combinations, which had generally similar scores. Therefore, calpain-system gene markers have beneficial effects on eating quality, consistent with our previous findings for objective meat quality

Gene expression patterns during intramuscular fat development in cattle

Deposition of intramuscular fat, or "marbling," in beef cattle contributes significantly to meat quality variables, including juiciness, flavor, and tenderness. The accumulation of intramuscular fat is largely influenced by the genetic background of cattle, as well as their age and nutrition. To identify genes that can be used as early biomarkers for the prediction of marbling capacity, we studied the muscle transcriptome of 2 cattle crossbreeds with contrasting intramuscular fat content. The transcriptomes of marbling LM tissue of heifers from Wagyu X Hereford (WxH; n = 6) and Piedmontese × Hereford (P×H; n = 7) crosses were profiled by using a combination of complementary DNA microarray and quantitative reverse transcription-PCR. Five biopsies of LM were taken from each animal at approximately 3, 7, 12, 20, and 25 mo from birth. Tissue was also collected from the LM of each animal at slaughter (approximately 30 mo). Microarray experiments, conducted on the first 3 biopsies of 2 animals from each crossbreed, identified 97 differentially expressed genes. The gene expression results indicated that the LM transcriptome of animals with high marbling potential (W×H) could be reliably distinguished from less marbled animals (PxH) when the animals were as young as 7 mo of age. At this early age, one cannot reliably determine meaningful differences in intramuscular fat deposition. We observed greater expression of a set of adipogenesis- and lipogenesis-related genes in the LM of young WxH animals compared with their PxH contemporaries. In contrast, genes highly expressed in PxH animals were associated with mitochondrial oxidative activity. Further quantitative reverse transcription-PCR experiments revealed that the messenger RNA of 6 of the lipogenesis-related genes also peaked at the age of 20 to 25 mo in W×H animals. The messenger RNA expression of ADIPOQ, SCD, and THRSP was highly correlated with intramuscular fat content of an individual in W×H animals. Our study provides clear evidence of early molecular changes associated with marbling and also identifies specific time frames when intramuscular fat development in cattle muscle can be detected by using gene expression. This information could be used by animal scientists to design optimal nutrition for high marbling potential. In addition, the genes found to be highly expressed during development of marbling could be used to develop genetic markers or biomarkers to assist with beef production strategies