Relationship of Endocrine Pathway SNP and Molecular Breeding Value with Milk Production in Heat Stressed Holstein Cows

Abstract Text:

Milk performance data were collected from lactating Holstein cows (n=660) in the Yaqui Valley, Sonora, Mexico where temperatures in summer average 32ºC. Cows were genotyped for 179 SNP from 41 genes in the growth hormone signaling and prolactin pathways. Twenty-four SNP had significant association with milk production traits and used to calculate molecular breeding value (MBV; 4448.8 ± 33 L) in 551 cows. Two statistical models were used: full model with effects for age, lactation season, contemporary group (farm management) and MBV, and a reduced model with MBV. The coefficients of determination among the models were compared and we found 2.7% of the variation in adjusted 305 days milk production (σ²=598.9x10^-3) was attributed to MBV. Our findings support our hypothesis, MBV predicts milk performance traits in heat stressed Holstein cows in Sonora.

Keywords:

SNP

PRL pathway

MBV