Programs for Developing and Feeding the Breeding Herd

Space allowance during rearing had no affect on growth rate backfat thickness and loin depth at 200 d of age or total pigs produced and removal rate. Gilts attaining puberty at < 185 d of age produced more pigs over parities 1 to 3. Gilts served at > 260 d of age produced fewer pigs over the 3 parities while a greater percentage of gilts served at > 280 d of age removed by the end of parity three. In experiment 2 a total of 684 sows were used to compare three methods of feeding during gestation and to assess the subsequent effects on lactation performance. Control gilts and sows were fed according to body condition while for treatments 2 and 3 feeding levels were based on backfat thickness (at breeding) and weight at weaning for sows or service for gilts to achieve a target backfat of 19 mm at farrowing. Feeding sows in gestation based on backfat (treatments 2 and 3) resulted in a higher proportion of sows in the target backfat range of 17 to 21 mm at farrowing and a lower percentage of fat sows (> 21 mm) but no difference in the percentage of thin sows (< 17 mm) compared to the standard method of feeding based on body condition.