Anti-Müllerian hormone (AMH) is proposed as a biomarker for fertility in cattle, yet this associative relationship appears to be influenced by heat stress (HS). The objective was to test serum AMH and AMH-related single nucleotide polymorphisms (SNPs) as markers potentially predictive of reproductive traits in dairy cows experiencing HS. The study included 300 Holstein cows that were genotyped using BovineSNP50 (54,000 SNP). A genome-wide association study was then executed. Nine intragenic SNPs within the pathways that influence the AMH gene were found important with multiple comparisons adjustment tests (p < 1.09 × 10⁻⁶). A further validation study was performed in an independent Holstein cattle population, which was divided into moderate (MH; n = 152) and severe heat-stressed (SH; n = 128) groups and then subjected to a summer reproductive management program. Serum AMH was confirmed as a predictor of fertility measures (p < 0.05) in MH but not in the SH group. Cows were genotyped, which revealed four SNPs as predictive markers for serum AMH (p < 0.01), reproductive traits (p < 0.01), and additional physiological variables (p < 0.05). These SNPs were in the genes AMH, IGFBP1, LGR5, and TLR4. In conclusion, serum AMH concentrations and AMH polymorphisms are proposed as predictive markers that can be used in conjunction with genomic breeding value approaches to improve reproductive performance in Holstein cows exposed to summer HS conditions.

Anti-Müllerian hormone (AMH) has been proposed as biomarker for fertility in cattle, yet this associative relationship appears to be influenced by heat stress. Objective was to test serum AMH and AMH-related single nucleotide polymorphisms (SNPs) as markers potentially predictive of reproductive traits in heat-stressed dairy cows. The study included 300 Holstein cows that were genotyped using BovineSNP50 (54,000 SNP) after blood samples were collected and DNA extracted. A genome wide association study was then executed. Nine intragenic SNPs within the pathways that influence the AMH gene were found important with multiple comparisons adjustment test (p<1.09x10-6). A further validation study was performed in an independent Holstein cattle population, which was divided into moderate (MH; n=152) and severe heat-stressed (SH; n=128) groups, and subjected to a summer reproductive management program. Serum AMH was confirmed as a predictor of fertility measures (p<0.05) in MH but not in SH group. Cows were genotyped using the TaqMan allelic discrimination method and qPCR, which revealed four SNPs as predictive markers for serum AMH (p<0.01), reproductive traits (p<0.01) and physiological variables (p<0.05). These SNPs were in the genes AMH, IGFBP1, LGR5 and TLR4. In conclusion, both serum AMH concentrations and AMH-related SNPs appear to be associated with fertility traits in dairy cows managed during summer.