The effect of energy intake and mating weight on growth, carcass yield and litter size of female pigs

Abstract

SUMMARY: 1. In a comparative slaughter experiment, 12 female pigs (six at 80 kg and six at 100 kg) were allocated at first oestrus to each of five treatments: Treatment 1, initial slaughter, or Treatments 2, 3 and 4, mated and given 19·5, 25·8 or 32·1 MJ ME/day for the last 100 days of pregnancy, or Treatment 5, not mated (virgin) and given 25·8 MJ ME/day over a similar period. Pigs on Treatments 2, 3, 4 and 5 were given the same amount of protein and were killed about 123 days after first oestrus. Piglets were removed at birth.2. There was no evidence of any special effect of pregnancy in the stimulation of permanent maternal growth. The average live weight, ingesta-free body and carcass gains of the pair-fed, mated and virgin gilts (±SE of difference) were, respectively, 32·3 and 36·9 + 2·8, 27·5 and 27·6 ± 3·4, and 26·0 and 26·7 + 2·1 kg. There were no statistically significant differences between these two treatments in carcass composition, specific gravity or backfat thickness. The mated pigs had lighter livers (P < 0·01) and heavier reproductive tracts (P < 0·05), and lost about 9 kg within a week of parturition.3. Increasing energy intake increased piglet birth weights (Pv. 80 kg) had 1·5 more piglets, though this was not statistically significant (P<0·1).4. Although there was no special effect of pregnancy on permanent maternal growth, the conversion of food by the once-mated pig was very efficient if an allowance was made for the food cost of producing the piglets.