Quantitative relationship between the number of cross-fostering piglets and subsequent productivity of sows on commercial swine farms.

The present study aimed to investigate the quantitative relationship between the number of cross-fostering (CF) piglets and subsequent productivity of sows. Data were obtained from seven commercial farms including 41,086 farrowing records. Sows were divided into those that fostered out three or more piglets (CF ≥ 3-), fostered out one or two piglets (CF1-2-), did not do CF (NCF), fostered in one or two piglets (CF1-2+), and fostered in three or more piglets (CF ≥ 3+). CF ≥ 3- sows had the lowest number of piglets weaned and the highest preweaning mortality rate, whereas CF ≥ 3+ sows had the second-lowest number of piglets weaned and the second-highest preweaning mortality rate (p < .05). The number of piglets weaned and preweaning mortality rate did not differ among CF1-2-, NCF, and CF1-2+ sows. CF ≥ 3+ sows had the lowest farrowing rate (p < .05). The number of piglets born alive at the subsequent parity was highest for CF ≥ 3- sows (p < .05), followed in order by CF1-2-, NCF, CF1-2+, and CF ≥ 3+ sows (p < .05). In summary, CF1-2- and CF1-2+ sows showed no decreases in productivity compared with NCF sows, whereas CF ≥ 3- and CF ≥ 3+ sows had reduced productivity.