Genetic Parameters for Tolerance to Heat Stress in Crossbred Swine Carcass Traits

Abstract

Data for loin and backfat depth, as well as carcass growth of 126,051 three-way crossbred pigs raised between 2015 and 2019, were combined with climate records of air temperature, relative humidity, and temperature–humidity index. Environmental covariates with the largest impact on the studied traits were incorporated in a random regression model that also included genomic information. Genetic control of tolerance to heat stress and the presence of genotype by environment interaction were detected. Its magnitude was more substantial for loin depth and carcass growth, but all the traits studied showed a different impact of heat stress and different magnitude of genotype by environment interaction. For backfat depth, heritability was larger under comfortable conditions (no heat stress), as compared to heat stress conditions. Genetic correlations between extreme values of environmental conditions were lower (∼0.5 to negative) for growth and loin depth. Based on the solutions obtained from the model, sires were ranked on their breeding value for general performance and tolerance to heat stress. Antagonism between overall performance and tolerance to heat stress was moderate. Still, the models tested can provide valuable information to identify genetic material that is resilient and can perform equally when environmental conditions change. Overall, the results obtained from this study suggest the existence of genotype by environment interaction for carcass traits, as a possible genetic contributor to heat tolerance in swine.

Genotype-by-environment interactions for reproduction, body composition, and growth traits in maternal-line pigs based on single-step genomic reaction norms

“…Overall, our results regarding G × E interactions in pigs are consistent with other reports for TNB and NBA [ 13 , 17 ]. However, different conclusions were previously reported for BF, including the absence [ 38 ] or presence [ 14 , 60 , 66 ] of G × E interactions in pigs. Moreover, Fragomeni et al [ 12 ] observed a significant G × E interaction for body weight at ~ 170 days of age in purebred Duroc but not in crossbred animals.…”

Definition of Environmental Variables and Critical Periods to Evaluate Heat Tolerance in Large White Pigs Based on Single-Step Genomic Reaction Norms

“…However, differently from Chen et al (2021), in the current study, stronger G×E interactions were observed for WN and moderate for OTW. Usala et al (2021) observed lower values for the genetic correlations in crossbred animals (0.89 and 0.50 for BFT and loin depth, respectively, using RH). These results suggest that the G×E interaction is not only population dependent but also dependent on the environmental covariate used.…”

“…Freitas et al (2006) estimated a correlation of 0.9 between on-farm weather data and weather station data even for weather stations more than 300 km away from the farm. Although these climate records are usually publicly available and have been successfully used in other worldwide studies focusing on sow HTol for different reproduction, growth, and carcass traits (Tummaruk et al, 2010;Wegner et al, 2014;Tiezzi et al, 2020;Usala et al, 2021), we acknowledge that the collection of withinbarn environmental measurements is important and should be done when possible. However, the variables needed for this study were not available for this current study.…”

“…As described by Usala et al (2021), the use of RNM to assess the environmental effect on animal fertility, conformation, or carcass quality traits is less common in pigs when compared to dairy and beef cattle (Meyer, 2000;Coffey et al, 2002;Bradford et al, 2016;Ansari-Mahyari et al, 2019). In pigs, the genetic component for HTol is usually calculated as a function of heat load on growth traits or carcass weight (Zumbach et al, 2008;Fragomeni et al, 2016).…”

“…In pigs, the genetic component for HTol is usually calculated as a function of heat load on growth traits or carcass weight (Zumbach et al, 2008;Fragomeni et al, 2016). Estimating genetic parameters for HTol in crossbred swine carcass traits, Usala et al (2021) also observed a high average h 2 for BFT and MDP. The heritability estimated for the beginning the curve (assumed as a comfortable condition compared to the right extreme values) was also a trend observed by Tiezzi et al (2020) for TNB and NBA.…”