Reaction Norm models for study genotype by environment interaction in Nellore cattle

Abstract

The objective of this study will be to evaluate the effect of different selection practices on reproductive and growth traits in males and females on the environmental sensitivity of cattle from three Nelore herds, in addition to estimating the genetic tendency for each herd both for the general production level as to the environmental sensitivity. Will be used about 7,233 information of the hip height (HH) in males and females, 3062 scrotal circumference information (SC) collected at 378 days of age in both males and 2,831 first days to calving (FDC) in females of the Nelore breed, born between 1981 and 2017 in the Center APTA beef cattle, the Animal Science Institute of Sertãozinho, SP. The (co)variance components and genetic parameters for the three traits in the three herds will be estimated using a standard animal model (MA) and two reaction norm model (homogeneous and heterogeneous residue). To verify the best fit model, the deviance information criterion (DIC) will be used. Genetic trends will be estimated for each herd and trait for both the general production level (RN intercept) and the specific ability to respond to environmental variations (RN slope).