Protease Supplementation Partially Alleviates the Negative Effects of Low-Protein Diets on Growth Performance in Weaned Piglets

This study evaluated the effects of reducing dietary crude protein (CP) levels and protease supplementation on growth performance, nutrient digestibility, and fecal score in weaned piglets. A total of 200 crossbred weaned piglets (Duroc × [Landrace × Yorkshire]), with an initial body weight (BW) of 6.01 ± 1.14 kg, were used in a 31-day feeding trial. Piglets were assigned to four dietary treatments in a randomized complete block design with 10 replicates per treatment and five piglets per pen. The treatments were as follows: CON, basal diet; TRT1, low-protein diet with CP reduced by 1%; TRT2, low-protein diet with CP reduced by 2%; and TRT3, TRT2 supplemented with 0.1 g/kg protease. Piglets fed TRT2 had lower BW on days 7, 19, and 31 (p < 0.05) and lower average daily gain (ADG) during each growth phase and the overall period compared with CON (p < 0.05). Protease supplementation partially restored BW and ADG. However, average daily feed intake (ADFI), feed conversion ratio (FCR), apparent digestibility of dry matter (DM), nitrogen (N), and energy (E), and fecal score were not affected by dietary treatments (p > 0.05). In conclusion, reducing dietary CP by 2% impaired growth performance in weaned piglets, whereas protease supplementation partially alleviated this negative effect without significantly altering nutrient digestibility or fecal score.