Sows having high lifetime efficiency and high longevity associated with herd productivity in commercial herds

The objectives of this study were to characterize sows having high lifetime efficiency and high longevity (HE–HL), to examine the relationship between lifetime measurements, and to determine the association between the sows and herd productivity. This study was conducted by obtaining sow data with 66,262 parity records of 13,786 sows born during 1999 and herd data with mean measurements of 4-year records from 2000 to 2003 in 92 herds. Sow lifetime efficiency was defined as the sum of pigs born alive in lifetime divided by the sow life days and multiplied by 365 days. Sows were categorized into three sow groups based on the upper 25 percentile of the lifetime efficiency and parity at culling ≥ 6. The three groups were sows having 1) the upper 25 percentile of the lifetime efficiency and parity at culling ≥ 6 (HE–HL sows), 2) less than the upper 25 percentile of the lifetime efficiency and parity at culling ≥ 6 (OE–HL sows), and 3) parity at culling ≤ 5 regardless of lifetime efficiency (LL sows). Mixed-effects models were used to compare reproductive performance between the three sow groups and to identify factors associated with a proportion of a HE–HL sow in the herd. Correlation analyses were done between lifetime performances in sows and between herd productivity measurements and the proportions of three sow groups in the herd. The proportions of HE–HL, OE–HL, and LL sows in 13,786 sows were 21.8%, 24.5%, and 53.7%, respectively. Lifetime efficiency was correlated with parity at culling (r = 0.76; P < 0.01) and nonproductive days per parity (r = − 0.46; P < 0.01). From first parity to the end, HE–HL sows had the greatest numbers of pigs born alive, the highest farrowing percentage, and the shortest nonproductive days per parity (P < 0.01). Sows aged between 186 and 227 days at first mating were 1.09 to 1.11 times as more likely to become a HE–HL sow as those aged between 249 and 269 days at first mating (P < 0.05). Of the 92 herds, mean proportion of HE–HL sows was 23.5%, and the proportions ranged from 0 to 57.6%. A higher proportion of HE–HL sows and a lower proportion of LL sows in the herd were correlated with more pigs weaned per mated female per year (P < 0.01). In conclusion, HE–HL sows had high efficiency from the first parity to the end, which was attributed to herd productivity.