Effect of Longer Pre-Starter Diet Allowance on Post-Weaning Performance of Lightweight Piglets.

First-phase diets are formulated to help pigs reach a target body weight before switching to a more affordable diet. However, these transitions typically take place on a fixed schedule, which may disadvantage low-body-weight piglets due to their underdeveloped digestive systems and limited feed intake capacity. This study examined the effects of offering low-body-weight (BW) pigs a pre-starter diet until they reached a target BW on growth performance and BW variability. A total of 528 pigs ([Landrace × Yorkshire] × Pietrain), weaned at day 21, representing the smallest 50% of their batch, were divided into medium (5.35 ± 0.31 kg) and small (3.97 ± 0.21 kg) groups based on weaning BW. Pigs received a pre-starter diet either for 10 days (FIXED) or until they reached a target BW of 7.9 kg (TBW), followed by a starter feed. Growth performance between the TBW and fixed strategies was similar over the 36-day period. Overall, mortality was higher in small pigs, though small pigs fed using the fixed strategy showed higher mortality than the rest of the groups between days 10 and 36. This study concludes that offering a pre-starter diet based on target BW, instead of a fixed time, did not significantly improve growth performance or batch uniformity but reduced mortality in small pigs from days 10 to 36.