Effects of post-farrowing feed delivery schedule and sow parity on piglet performance and survivability¹

Pre-wean mortality (PWM) in commercial pig herds typically ranges from 10% to 20%, with most deaths occurring within 72 hours of birth. Crushing by the sow is a primary cause of piglet deaths. Early in lactation, piglets spend more time near the sow for warmth which is also the period of sow recovery from farrowing, which may increase the risk of crushing. Consequently, sow feed delivery schedule (ie number of feed deliveries per day) during this period may influence piglet survival by altering sow activity patterns and slowing recovery from farrowing. This study evaluated the effects of post-farrow feed delivery schedule and sow parity on sow lactation performance and piglet PWM. A total of 261 sows (Parity 1 to 9) in 8 rooms of approximately 32 sows/room) were assigned to one of three lactation feed delivery schedules beginning at farrowing: six meals per day (Feed-6), two meals per day (Feed-2), or two meals per day for the first five days post-farrow followed by six meals per day until weaning (Feed-2/6). Sow and litter performance to wean were recorded, as well as sow pre-farrow hemoglobin concentration and piglet mortality causes. Data was analyzed using SAS (Version 9.4) in a randomized incomplete block design with farrowing room as the blocking factor and sows as the experimental unit. Continuous outcomes were analyzed using PROC MIXED with feed delivery schedule, parity group and their interaction as fixed effects, and farrowing room included as a random effect. Outcomes that did not meet distributional assumptions, including feeder bowl coverage score, were analyzed using PROC NPAR1WAY. Statistical significance was declared at P ≤ 0.05. There was no interaction between feed delivery schedule and parity. Total lactation feed intake was greater (P < 0.04) in Feed-2 sows than in Feed-6 and Feed-2/6 sows. Litter performance did not differ among feed delivery schedules; litter size at wean, wean weight, average daily gain, and PWM were comparable across all groups. In contrast, sow parity had a marked effect; older parity sows (parity 4+) had greater total feed intake (P < 0.03) than parity 1 sows and higher PWM due to crushing (P = 0.003) and stillborn piglets (P < 0.001) compared to parity 1, 2 and 3 sows. Pre-farrow hemoglobin concentration was lower (P < 0.05) in 3 and 5+ parity sows than in young sows. These findings indicate that sow age/parity, rather than post-farrowing feed delivery schedule, was associated with piglet mortality outcomes and highlights the importance of incorporating sow parity into management strategies to improve piglet survival rates.