The importance of sow functional teat assessment and provision of supplementary milk to enhance performance of piglets reared in large litters

Rearing piglets in large litters where there are supernumerary piglets compared to functional teats presents a challenge in maintaining piglet health by avoiding successive fostering, whilst minimising mortality caused by starvation. Supplementary milk (SM) provision to litters during the suckling period has been shown to reduce preweaning mortality, but there has been no characterisation of which piglets consume SM and the subsequent performance effects. Using electronic identification (RFID) tags and an antenna at the SM bowl, it was possible to record the duration of each visit for each individual piglet. Multiplying individual piglet weight and duration of SM visits for each day, and summing for the litter showed a positive relationship with daily weighed litter SM consumption during lactation, yielding a regression equation with r² = 0.84. Therefore, the daily duration of visits to the SM bowl was considered a proxy measure of daily individual piglet SM consumption. Litter SM consumption during lactation, measured both by weighing SM and by calculation using the regression equation, was greater in litters where there were supernumerary piglets compared to functional teats (IS), than in litters where there were no supernumerary piglets (S). Litter weight at each timepoint was greater for IS litters than for S litters, but average piglet weight was lower. Piglets with very high duration of SM visits/d during the final week of lactation were lightest at weaning, and at d 54 postweaning, with the lowest postweaning average daily gain (ADG). Piglets suckling posterior teats had a higher duration of SM visits/d than piglets suckling anterior teats, throughout lactation. Piglets observed as non-sucklers on d 14 had the highest du/d throughout the suckling period and were lightest at weaning. The SM DM feed conversion ratio for non-suckling pigs predicted using the regression equation was 0.88. This was higher than the predicted 0.70 for piglets suckling sow milk, indicating lower efficiency of piglet growth from SM. This may be due to reduced fat and protein content of SM compared to sow's milk; therefore, further investigation of the composition of SM and refinement of the formulation is warranted. Validation of the methodology employed to estimate SM consumption from the duration of SM visits/d is also necessary.