Disease & heat resistance

Genetic Analysis of Conception Success under Heat Stress in Gir Dairy Cattle

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Abstract

The Gir breed, recognized for its hardiness (or rustic nature) and adaptability to hot climates, plays a crucial role in dairy production in tropical regions. However, heat stress (HS), a growing challenge due to climate change, can negatively impact its productivity. This study estimated the genetic parameters for Conception Success (CS) in Gir cows under HS, aiming to support breeding programs. A total of 1,461 conception records from 641 Gir cows were analyzed. The CS trait was modeled as binary (1=Success, 0=Failure) for conceptions occurring under HS, defined as a temperature-humidity index (THI) above 78.99. The analysis was performed using the ssGBLUP animal model and Bayesian inference, considering the fixed effects of Contemporary Group (Farm, Year, and Season of calving) and age at conception (covariate), in addition to the random additive genetic and permanent environmental effects. The H-1 matrix was constructed by including the genotypes of 174 phenotyped cows and 1,419 relatives. The estimates for heritability (h2) and repeatability were 0.08 (0.04) and 0.19 (0.06), respectively. In conclusion, although the h2 estimate appears low, it demonstrates that CS is a promising selection criterion. The resulting genetic evaluations will allow for the identification of bulls with a higher probability of producing daughters resilient to HS, directly contributing to the sustainability of the Gir breed in a global warming scenario.

Keywords: 2026

How to Cite:

Silva, J., Mota, R., Gonçalves, A., Buzanskas, M. & Dominguez-Castaño, P., (2026) “Genetic Analysis of Conception Success under Heat Stress in Gir Dairy Cattle”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2287327. doi: https://doi.org/10.31274/wcgalp.24266

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