Identifying the optimal ratios for replacing spray-dried plasma protein with hydrolyzed porcine intestinal protein in weaning pig

This study aimed to evaluate the effects of replacing spray-dried plasma protein (SDPP) with hydrolyzed porcine intestinal protein (HP) in weaning pigs and determine the optimal replacement ratio. Ninety-six crossbred weaning pigs (initial body weight 7.35 ± 0.67 kg) were used for five weeks and assigned to four dietary treatments: HP0 (100% SDPP), HP25 (25% HP), HP50 (50% HP), and HP100 (100% HP), with 6 replicates of 4 pigs per treatment. The HP0 and HP25 diets significantly increased (p < 0.05) average daily gain (ADG) and feed efficiency (G:F) compared with HP100 at weeks 3 to 5 and over the entire study period. Increasing levels of HP replacement linearly decreased (p < 0.05) ADG and G:F. At week 3, HP0 and HP25 diets significantly increased crude protein (CP) digestibility compared to HP50 and HP100, with similar results observed at week 5. Additionally, HP0 and HP25 diets led to significantly lower (p < 0.05) total protein (TP) and blood urea nitrogen (BUN) levels than HP50 and HP100 at week 5. TP and BUN levels increased linearly as HP levels increased. The HP25 diet notably increased Lactobacillus counts in feces compared to HP50 and HP100 at week 5. Total weight gain was significantly higher (p < 0.05) in the HP0 and HP25 groups compared to HP100, and the HP25 diet significantly reduced feed cost per kg gain (FCG) compared with HP100. Moreover, during the study, the HP25 diet showed a trend (p = 0.087) towards lower FCG compared with HP0. In conclusion, replacing 25% of SDPP with HP provides optimal benefits in growth performance, nutrient digestibility, and feed cost efficiency without negative impacts on weaning pigs.