Fatness, live weight and performance responses of sows to food level in pregnancy

Abstract

AbstractSixty crossbred females received one of three pregnancy feeding rates over five parities: high (2·3 kg/day); medium (2·0 kg/day) and low (1·7 kg/day) to produce variation in body fatness and live weight. During a 32-day lactation all sows were fed the same allowance according to litter size. At the start of parity 5 ultrasonic P2 backfat depths for the high, medium and low treatments respectively were 11·2, 11·0 and 10·6 (s.e. 1·77) mm while live weight was 184, 177 and 167 (s.e. 8·6) kg. Averaged over five parities, backfat depths at conception were not significantly different between treatments. Sows given higher pregnancy feeding rates in pregnancy were heavier and fatter pre-partum but lost relatively more live weight and backfat during lactation. Regression coefficients for the slope of the relationship between total sow pregnancy weight (kg) and fatness (mm) change, and food intake (kg/day) were 0·2 and 0·04 respectively. Pregnancy feeding rate did not influence the number of live births but total litter weight at weaning was positively related to the weight and fatness of the sow at parturition and her subsequent rate of weight and fat loss during lactation (these characteristics of the sow also being positively related): live weight of litter at 32 days (kg) = 67 – 1·8 sow backfat change in lactation (mm) – 0·4 sow live-weight change in lactation (kg). Absolute sow live weight and fatness were positive influences on readiness to rebreed after weaning.