Effects of gilt age at first mating and levels of dietary Ca and P during gestation on sow and litter performance

Abstract

Puberty was induced, using boars as a stimulus, in 83 grade Large White gilts starting on average at 162 days of age and 82.9 kg live weight. Gilts were allocated to three mating groups and mating was done over a 21-day period starting 19, 40, or 60 days from the start of induction. Matings corresponded to first, second, and third post-pubertal heats. Each mating group was randomised to 3 Ca and P levels in gestation corresponding to daily intakes of 7.8 and 6.2 (L), 12.3 and 8.4 (M), and 16.5 and 10.4 g (H) respectively. Of the 73 gilts mated 27 returned to service a second time, were culled, and their ovaries examined. Forty–six gilts farrowed to a single and first service and were kept for up to 3 parities when 31 remained. Average ages and weights respectively of the 46 gilts at first mating for the 3 groups were 189.7 days, 97.8 kg; 207.5, 103.3 kg; and 233.0, 115.9 kg. Apart from a depression in litter weight at weaning in Parity 1 for the earliest mated group no other differences were associated with initial mating groups. The higher intakes of calcium and phosphorus resulted in a lowering of the litter weight born and, less frequently, weaned. Although several mating groups X Ca and P level interactions were found for litter trials, these generally occurred within parities and were not consistent between parities. Despite early mating of gilts and their low live weights, daily intakes of 7.8 g of calcium and 6.2 g of phosphorus in gestation were apparently adequate for good sow and litter performance in the presence of high intakes in lactation.