Characterization of Tenderness-Related SNPs in Culled Holstein Cows: CAPN1 and CAST Genotypes Show Neutral Effects on Postmortem Meat Quality Parameters—A Pilot Study

Meat from cull dairy cows is often used for human consumption; it is well known that tenderness adds value to the market, and dairy cattle meat is usually undervalued. In Mexico, most meat production comes from young bulls, mainly Bos indicus and commercial crossbreeds, whose meat tends to be tough rather than tender. The present study evaluated the association of G530A (CAPN1) and C357G (CAST) polymorphisms (PCR-RFLP) with meat tenderness using the Warner–Bratzler shear force (WBSF) method. Additionally, the color, pH, and marbling of meat cuts from culled Holstein cows were determined at 72 h postmortem. CAPN1 G530A genotype frequencies were GG (50%), AG (46%), and AA (4%), and for CAST C357G, they were CC (36%), CG (42%), and GG (22%); for both SNPs, the Hardy–Weinberg equilibrium was observed. Genotypes for CAPN1G530A and CAST C357G did not have a significant effect on WBSF (p > 0.05). Shear force (kg) for CAPN1 G530A genotypes was 4.02 ± 0.14 (GG), 3.99 ± 0.13 (AG) and 4.43 ± 0 (AA); and for CAST C357G genotypes, it was 4.0 ± 0.17 (CC), 4.09 ± 0.13 (CG) and 3.98 ± 0.11 (GG); the polymorphisms did not affect significantly WBSF, suggesting the limited applicability of these SNPs for meat tenderness in dairy cattle. However, due to the small sample size (n = 50) and especially the low number of CAPN1 AA homozygotes (n = 2), this study should be regarded as a proof-of-concept pilot investigation. The results warrant validation in larger cohorts.