Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract only
Publication Acceptance Date: 2/24/2013
Publication Date: 7/20/2013
Citation: Tait Jr, R.G., Cushman, R.A., Smith, T.P., Freetly, H.C., Bennett, G.L. 2013. CAPN1 and GDF8 genetic marker effects on heifer performance, reproduction, and first calf performance traits in beef cattle [abstract]. Journal of Animal Science. 91(E-Supplement 2):392. Interpretive Summary:
Technical Abstract: To increase the accuracy of effect estimation and assess potential unintended correlated effects for two marker systems used commercially for muscling and meat tenderness, a composite beef cattle population segregating the markers was selected for multiple years to increase minor allele frequency (MAF) or frequencies of divergent haplotypes (FDH). Substantial increases in FDH and MAF were achieved, with SNP haplotypes in the µ-calpain 1 gene (CAPN1) (haplotypes C-C or G-T at markers 316 and 4751, respectively) with haplotype increases from 0.264 to 0.386 and 0.195 to 0.332, respectively, and a lysine encoding allele (L) of the F94L marker in myostatin (GDF8) increased MAF from 0.282 to 0.450. The objective of this study was to understand if these markers affect female performance and reproductive traits. Heifers born between spring of 2007 and 2009 from this population (n = 149) were evaluated using MIXED and GLIMMIX procedures of SAS for birth weight, weaning weight, weight at 326 d, 368 d, or 411 d, achieving puberty by 326 d, 368 d, or 393 d, first breeding season pregnancy status, success of weaning first calf. Additionally, first calf performance traits of: birth date, birth weight, weaning weight, weight of calf weaned per cow exposed, and 205-d adjusted weight of calf weaned per cow exposed were evaluated. There were suggestive effects (P < 0.10) for GDF8 on own birth weight and CAPN1 on own weaning weight. GDF8 had significant effects (P < 0.05) on puberty, with LL homozygotes having a lower proportion of heifers pubertal than FL or FF genotypes, at all three time points. However, the delayed puberty effect of GDF8 did not lead to an effect on pregnancy rates (P = 0.53). CAPN1 haplotype of the cow did significantly affect (P < 0.05) first calf birth weight. Other own performance, reproduction, and first calf performance traits were not effected (P > 0.10) by CAPN1 or GDF8 genetic markers in this study. These marker effects for unintended traits may be important for incorporation into the breeding objective and for marker-assisted management strategies.