The effect of nurse sow parity and extended lactation length on piglet weaning outcomes and subsequent prolificacy of nurse sows

Nurse sows are used for nursing surplus piglets in hyper prolific pig herds, thereby extending their lactation. We examined weaning outcomes and effects of extended lactation length (ELL) of nurse sows on subsequent (sub) prolificacy (live-born LB, still-born SB, and mummies Ms). A total of 18,107 nurse sows were analysed. The data encompassed nurse sows of parities (P1–P6) and three ELL categories: 0–7 d, 8–14 d, and 15–21 d. General linear mixed-effects models were applied to the data. Nurse sows weaned 12.43 piglets during the 1st wean event (W1) and 10.82 piglets during the 2nd wean event (W2). Parity effects were detected (p < 0.05) in both W1 and W2 piglets but not group effects. The highest (p < 0.05) number of W1 piglets was recorded for P2 sows and the lowest for P6 sows. Parities 1–4 nurse sows weaned a higher (p < 0.05) number of piglets during W2 than parities 5 and 6. Subsequent LB for nurse sow parity differed significantly (p < 0.05), with the highest being recorded for parities 2–5. Parities 3–6 showed a significant number of Sub SB. Subsequent Ms were higher in parities 2–6. Extending lactation length for 15–21 d resulted in higher (p < 0.05) Sub LB for parity 1 nurse sows. A similar ELL (15–21 days) resulted in significant (p < 0.05) Sub Ms for P3 nurse sows. No effect (p > 0.05) of any ELL on Sub SB was observed. An optimal balance between piglet weaning outcomes and future reproductive performance can be achieved by selecting younger sows and carefully managing ELL.