785. Breeding for component traits of litter size at day 5 increases piglet survival while maintaining litter size at day 5

We tested the hypothesis that selection for component traits of live piglets at day 5 (LP5) realises more genetic gain ( ΔG ) for piglet survival than selection for LP5 while maintaining ΔG for LP5. We tested this premise by stochastic simulation of the breeding scheme for Danbred’s Landrace pigs. We estimated ΔG for LP5 and piglet survival realised by selection for (i) an index for LP5 and (ii) an index for TNB and piglet survival at 1% rate of inbreeding. Selection for index TNB and survival realised about 30% more ΔG for piglet survival than selection for the LP5 index while realising the same ΔG for LP5. Clearly, it is worthwhile separating LP5 into its component traits: it realises more ΔG for piglet survival while maintaining ΔG for LP5.