A survey of preweaning mortality in the pig.

Preweaning mortality was studied in 34 commercial piggeries on the North Coast of New South Wales during a 12-month period. For the 1,068 farrowings recorded, the mean litter size at birth was 10.4 and 0.6 piglets per litter were stillborn. The mean total mortality to weaning was 19.7%, but for individual herds the figure varied from 5.1 to 48.2%. A number of biological factors influenced the extent of preweaning mortality. Most losses (74.6%) occurred during the first 4 days of life. The mortality increased significantly with increasing litter size at birth, but the mean litter size at weaning also increased up to 10.5 in litters of originial size 14. Neither the breed nor parity of the sow had a significant effect on preweaning mortality, but the mean number of piglets weaned increased with parity up to sows on their fifth farrowing. Some management factors also influenced mortality. Piggeries using farrowing crates had significantly fewer losses than those not using crates. Within the group not using crates the intensive units had a higher preweaning mortality than either the mixed or sideline. Size of piggery had no influence on piglet losses.