Phenotypic, environmental and genetic associations between health and growth in the pig

Genetic improvement of multiple production traits is widely achieved in pig breeding. However, there have been claims that selection for productivity alone has been detrimental to pig health (Prunier et al. 2010). This study aims to explore the phenotypic, environmental and genetic relationships between health and growth of the pig. Performance records from 1998 to 2013 (n = 31,230) and medication records from 2011 to 2016 (n = 812) were obtained from a herd of Large White pigs from the University of Queensland piggery in Gatton, QLD. Average daily gain (ADG) was calculated when pigs were at the average end weight of 90 kg and age of 128 days. A health trait was derived using medication status, with 0 as not medicated (good health) and 1 as medicated (poor health) (Guy et al. 2018). The association between ADG and health was explored on 3 levels: 1) phenotypically, using multiple regression to model ADG, with the predictor variables of sex, health status, numbers born alive in the litter, season and birth-month contemporary group; 2) environmentally, using Pearson's correlation between the frequency of medication and the environment, which was quantified through contemporary group estimates of ADG (Guy et al. 2017); and 3) genetically, by fitting a bivariate sire model in ASReml (Gilmour et al. 2009).