Reproductive performance of second parity sows: Relations with subsequent reproduction

The objective of this study was to determine relations between reproductive performance, i.e. being a repeat breeder and litter size, in 2nd parity and reproductive performance in later parities. In addition, relations between the 1st and 2nd parity litter size and litter size in later parities were determined. First, 184,135 records from 46,571 sows were used to analyze the effect of being a repeat breeder in 2nd parity on subsequent farrowing rate, litter size and parity number at culling. Second, 161,521 records of 39,654 sows were used to analyze the effect of litter size from 1st insemination in 2nd parity, being either low (≤ 10 piglets total born), medium (11-13) or high (≥ 14), on subsequent litter size, farrowing rate and parity number at culling, with litter size in 1st parity included in the model as well. In total 15.7% of the sows inseminated in 2nd parity were a repeat breeder in 2nd parity. Being a repeat breeder in 2nd parity did not affect litter size in subsequent parities, however it decreased farrowing rate in parity 3 (4.1%) and 4 (3.4%), but not in later parities (P < 0.05). Repeat breeders in 2nd parity were culled on average 2 parities earlier compared with non-repeat breeders (resp. parity 5 vs. 7, P < 0.05). Sows with a low litter size in 2nd parity showed a lower litter size in parity 3 and up compared with sows with a medium or high litter size in 2nd parity (P < 0.05). The magnitude of this effect, however, decreased if litter size in 1st parity increased. For example, the difference in piglets born in parity 3-5 between sows with a low and high litter size in 2nd parity was − 4.6 piglets for sows with a low litter size in 1st parity. This difference decreased to − 3.3 piglets for sows with a high litter size in 1st parity. Sows with a high litter size in 2nd parity had 2% lower farrowing rate in parity 3, but not in later parities. Sows with a low litter size in 2nd parity were culled 1 parity earlier compared with sows with a medium or high litter size in 2nd parity. This study showed that a large part of the sows with poor reproductive performance in 2nd parity can be expected to have a poor reproductive performance in subsequent parities. The effect of 2nd parity litter size on subsequent litter size, however, depends on 1st parity litter size.