Search

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 calpastatin (CAST) and calpain 3 (CAPN3) gene markers for beef tenderness. Gene marker status for [mu]-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 hormortal 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[degrees]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 < 0.001, NSW) and 9.3 N (P = 0.002, WA) in AT 7 d aged M. longissimus lumborum compared with those with no favorable alleles. There was no evidence (all P > 025) 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. Key words: calpain, calpastatin, cattle, genetic marker, meat quality, shear force doi: 10.2527/jas.2009-2679

Experiments were conducted concurrently at 2 locations to quantify effects and interactions of calpain-system tenderness gene markers on growth, efficiency, temperament, and carcass traits of Brahman cattle. Cattle were selected at weaning from commercial and research herds based on their genotype for commercially available calpastatin (CAST) and calpain 3 (CAPN3) gene markers for beef tenderness. Genotypes for [mu]-calpain gene markers (CAPN1-4751 and CAPN1-316) were also determined and included in statistical analyses. The New South Wales (NSW) herd was composed of 82 heifers and 82 castrated male cattle with 0 or 2 favorable alleles for CAST and CAPN3. The Western Australia (WA) herd was composed of 173 castrated male cattle with 0, 1, or 2 favorable alleles for CAST and CAPN3. One-half of the cattle at each site were implanted with a hormonal growth promotant (HGP: Revalor-H) during grain finishing. Cattle were backgrounded at pasture for 6 to 8 mo and grain-fed for 117 d (NSW) or 80 d (WA) before slaughter. Individually, or in combination with each other and with CAPN1-4751 status, CAST and CAPN3 status had no significant (all P > 0.05) effects on BW, growth, feed efficiency, or temperament traits. The only significant effect of CAST or CAPN3 on carcass characteristics was a small increase in rib fat with increasing number of favorable CAST alleles (P = 0.042) in the WA herd. There were no significant interactions (all P > 0.05) between the markers, or between the markers and sex or HGP treatment apart from CAST x HGP for area of the M. longissimus lumborum (P = 0.024) in the NSW experiment. Favorable CAST or CAPN3 alleles appear unlikely to have detrimental effects on growth, efficiency, temperament, or carcass characteristics of Brahman cattle; however, some effects evident for CAPN1 status indicate the need for further production studies on effects of these markers. Overall, the findings of the present study indicate that calpain-system gene markers are suitable for use in marker-assisted selection to improve meat tenderness in Brahman cattle without negative effects on other production and carcass characteristics. Key words: calpain, calpastatin, carcass, cattle, genetic marker, growth doi: 10.2527/jas.2009-2678

Ultrasound measurements by trained and accredited sonographers on 9,232 Angus, Hereford, and Polled Hereford cattle at an average age of 450 d were used to estimate genetic and environmental (co)variances for weight at scanning (Wt), longissimus muscle area (LMA), longissimus muscle area adjusted to a constant weight of 400 kg (LMAawt), and fat depths at the rump and 12/13 rib sites. Estimated kilograms (ESMkg) and percentage of saleable meat yield (ESM%) were also calculated and analyzed. Subjective muscle scores, available for 2,488 animals, were also included in the analysis. Estimated heritabilities were 46% for Wt, 21% for LMA and LMAawt, 37% for rump fat, 30% for rib fat, 15% for muscle score, 44% for ESMkg, and 36% for ESM%. The two measurements, LMA and LMAawt, had high genetic (.82) and environmental (.91) correlations. The two fat depths were also highly correlated (.86 genetic; .67 environmental). Weight at scanning was moderately correlated with LMA (.45 genetic; .41 environmental). Differences between breeds could not be detected, but some variation in parameter estimates between data sets of the same breed was observed. Environmental correlations between fat depths or muscle score and Wt were approximately .3; genetic correlations were .07 to .12. Subjective muscle score had marginally higher genetic correlations with LMA than with LMAawt (.22 vs .08) but similar environmental correlations (.31 vs .27). Results show that carcass traits measured by ultrasound and predictions of meat yield have genetic variability, are moderately heritable, and that genetic progress based on genetic evaluation by mixed-model analysis can be made.

An accreditation system for sonographers who measure carcass traits of breeding animals was evaluated. Ultrasound operators at three clinics were assessed for theoretical knowledge of ultrasound scanning technology and repeatability and accuracy of carcass and scanned measurements. There were high correlations of scanning results with carcass measurements for rump fat, rib fat and longissimus muscle area. Ultrasonic scanning is accurate and effective in predicting carcass measurements however, the development and maintenance of technique is emphasized.

Some individuals suffer hypogonadism, or underdevelopment of the gonads, as a result of inadequate secretion of gonadotropin releasing hormone from the hypothalamus. Such individuals are generally healthy, and the condition is most often recognized by delayed puberty. Hypogonadotropic hypogonadism is often associated with anosmia, a failure to be able to smell certain odors. The combination of these two symptoms is referred to as Kallmann's syndrome. Careful examination is uncovering further neurological deficits in these patients, and research into visual spatial attention has now demonstrated not only another deficit, but also how subtle some neurological impairments can be. Twenty-four normal control males and 15 male patients with hypogonadotropic hypogonadism were asked to perform a test of visual spatial attention; the subjects concentrated on a light in the middle of a screen and were asked to press a button when a target light appeared on the left or right side. The appearance of the target was preceded by a cue light; sometimes the cue was on the same side as the target (the 'valid' cue) and sometimes the cue was on the side opposite to the target (the 'invalid' cue). The patients performed the task more rapidly than the normal controls, that is, the response time to the button press was invariably shorter among the patients. When the data were analyzed and subsets of the patients were examined, some other trends emerged. Nine of the patients were observed to have mirror movements; when a voluntary movement with one limb is made, movements in corresponding muscles can be observed in another limb. In the 15 patients in this study, all six anosmic patients also exhibited mirror movements. Most individuals show a validity effect, which is a shorter response time with a valid cue than an invalid cue. The patients with mirror movements responded more quickly to targets on the right when the cue was valid than when it was invalid. However, the response time for these patients was comparable for targets on the left side regardless of the validity of the cue. The results indicate that all patients responded more quickly than controls in a test of visual spatial attention, and there is a subset of these patients with a subtle attention defect. (Consumer Summary produced by Reliance Medical Information, Inc.)