Estimates of genetic parameters associated with lactation feed intake and growth and composition traits measured during a performance test.

Abstract

Days to reach 113.4kg, adjusted backfat depth and adjusted loin muscle area to 113.4kg were evaluated on pure-bred Landrace (n=15660) and Yorkshire (n=14808) boars and gilts. Daily lactation feed intake (LFI) was recorded within parity records from pure-bred Yorkshire (n=1587) and Landrace (n=2197) females during day 1-22 of lactation, and LFI curves were predicted using a mixed model. Evaluation of feed intake differences between 2 consecutive days of lactation resulted in the following periods: day 1-6 (PB1), day 7-10 (PB2) and day 11-18 (PB3). Average rate of change in intake (ARC), average daily intake (ADI) and variation from predicted daily LFI values (VAR) metrics were computed for each period of lactation. Gibbs sampling was used to estimate the genetic covariance between LFI metrics and grow-finish traits. Genetic correlations were strongest between grow-finish traits, and LFI metrics in first parity sows and were generally favourable, but correlations with LFI metrics during parity 2 or greater were low and not different from 0 (p>0.05). Genetic correlations between LFI metrics in parity 1 sows with growth and composition traits varied greatly in strength and direction. Selection for leaner, heavier muscled gilts had a limited effect on LFI metrics. However, selection for increased growth rate was associated with higher ARC and ADI and smaller VAR values.