Associations between sow body composition, feed intake during lactation and early piglet growth

The genetic and phenotypic associations between sow body composition, early piglet growth and lactation feed intake (LFI) recorded during the first lactation were estimated using data collected from two maternal lines (N~2500). Heritability estimates for lactation feed intake, average piglet birth weight (ABW) and total born (TB) were 0.16±0.04, 0.27±0.03 and 0.10±0.04; genetic correlations between LFI and ABW or TB were positive but not significantly different to zero. Heritabilities for sow weight and fat depths prior to farrowing and at weaning ranged from 0.27 to 0.37 (±0.05) and within trait genetic correlations between these time points were less than one. Positive genetic (ra) and phenotypic (rp) correlations show that increased LFI is associated with higher sow weaning weight and fat depths (ra: 0.52±0.13 and 0.21±0.16; rp: 0.38±0.02 and 0.15±0.03) and higher litter gain (ra: 0.10±0.24, rp: 0.20±0.02). While correlations are not antagonistic between LFI and TB, ABW or litter gain, any correlated response in LFI to selection on these traits would be low.