Sow weight changes during reproduction and the effect of breeding system on litter performance

摘要

Abstract The sow and litter performance of 137 sows from four breeding systems was examined over a 4-year period. Sows produced two litters in a year and then each was replaced for the following year. Gilt replacements were taken from first litters. The breeding systems involved a purebred Large White group and three crossbred groups. Crossbred groups comprised a three-breed rotational cross between Berkshire, Large White, and Landrace; a back-cross group between Berkshire and Large White; and a cross-to-cross group in which Berkshire × Large White females were mated to F1 boars of the same two breeds. Whereas these systems were followed for gilt matings, all sows were mated with Large White boars for their second litters. Parity affected both mating weight and sow live-weight loss during suckling. Lactation weight loss by the sow was not held constant by the level of feeding. While total pregnancy gain and net sow gain were generally greatest in parity 1, a parity × year interaction showed that this did ...