Exogenous protease supplementation to the diet enhances growth performance, improves nitrogen utilization, and reduces stress in finishing pigs.

We have conducted this experiment to evaluate a new exogenous protease in finishing pigs' growth performance, nutrient digestibility, gas emission, blood profiles, and meat quality. A total of 200 pigs of 52.15 ± 2.31 kg average body weight (BW) were divided into four dietary treatments named as: CON, basal diet; TRT1, basal diet + 0.05% protease; TRT2, basal diet + 0.1% protease; TRT3, basal diet + 1.5% protease. Each treatment consisted of 10 pens, where five pigs were allotted to each pen according to their body weight and sex. The dietary treatments were allotted to the pens in a randomized block design. During this 10-week-long experiment, BW, average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F) were calculated for Week 0-5, Week 6-10, and the overall period. During Week 6-10, ADG was higher in TRT2 and TRT3 than in the CON and TRT1 groups. At the same time, a linear increase was observed in ADG and G:F of the pigs. In addition, the final BW of pigs' was linearly increased by protease supplementation. On Week 10, there was a linear trend of increase (p = 0.0575) in crude protein digestibility and a trend of linear reduction (p = 0.0651) in NH gas emission. In blood profile, cortisol presented a linear decrease in both Week 5 (p = 0.251) and Week 10 (p = 0.0585). In addition, increasing doses of protease showed a trend of linear increase (p = 0.0592) in creatinine, whereas linear reduction was observed in the concentration of epinephrine (p = 0.0636) and norepinephrine (p = 0.0167) during Week 10. In conclusion, protease supplementation helped in improving daily gain in finishing pigs through protein digestibility with associated reduction of ammonia emission and blood stress hormones.