Effects of L-phenylalanine supplementation on hyperprolific sow and litter performance during lactation

This study sought to determine the effect of L -phenylalanine (Phe) on reproductive traits on high prolific sows and their litters.The experiment was conducted using 36 crossbred sows (Duroc × Landrace × Yorkshire; body weight [BW] 225.22 ± 17.77 kg; parity 3; gestation length of 114 -116 days).The sows were grouped into two categories based on their litter size: group 1 (18 sows with lower litter size: 11 -15 piglets per sow) and group 2 (18 sows with higher litter size: 16 -20 piglets per sow).The dietary groups consisted of: (1) corn-soybean meal basal diets (CN); (2) CN + 0.2% Phe (CP2); (3) CN + 0.4% Phe (CP4).Each dietary group was replicated across twelve stalls, with 6 sows in each category.The dietary intervention was administered from the 90th day of gestation until the 21st day of lactation.Results revealed that supplementing 0.2% or 0.4% Phe did not affect BW, average daily feed intake, estrus interval, interaction between sow and Phe, back fat thickness, litter size, piglet survivability, milk composition, or thyroxine level, regardless of litter size.Sows with large litter size experienced greater BW loss with higher initial and weaned litters (p < 0.05).In contrast, piglets from sows with smaller litters exhibited higher (p < 0.05) weights at both birth and weaning.In conclusion, Phe was not able to specifically enhance the reproductive qualities or growth performance of lactating sows.