Longitudinal modelling of performance and feed efficiency traits in growing Duroc pigs

Abstract

In this study we used the phenotypic information of 1,499 Duroc pigs, recorded longitudinally in the age period from 110 to 200 days of age for individual daily feed intake (DFI), backfat thickness (BF) and live body weight (BW). Our aim was to estimate the genetic parameters for production and feed efficiency traits during the fattening period, with the objective to define, based on these parameters, the optimal moment for recording the phenotypes in order to maximize the expected response in a selection program to improve feed efficiency. Additionally to the aforementioned traits, two other traits were derived: average daily gain (ADG) and residual feed intake (RFI). The variance components for these traits were estimated through Bayesian procedures and using a multi-trait random regression animal model fitting Legendre polynomials of degree one. The estimated heritability patterns along the fattening were fairly flat, around 0.15(0.04), 0.37(0.05) and 0.34(0.09) for DFI, BF and DWG, respectively. RFI was the trait with the lowest heritability estimate, below 0.05 from 140d onwards. The only trait that showed relevant variation in the heritability estimate along the fattening period was BW, from 0.18(0.05) to 0.32(0.10). The correlations between performance at different moments of the fattening period and those at 120 days, was not always high. For the case of DFI and RFI these correlations reached values as low as 0.27(0.18) and -0.26(0.23). This points to a certain degree of genetic determinism variation along the studied period. Nonetheless, in particular for the feed efficiency trait (RFI), this variation seems irrelevant given the low estimated heritabilities and the low level of genetic heterogeneity along the fattening period.