Preliminary evaluation of papain: its enzymatic characteristics and effects on growth performance and nutrient digestibility in weaned piglets

The present study was conducted to investigate the influence of papain (Carica papaya L.) on performance and nutrient digestibility of weaned piglets and to evaluate whether soy protein ingredients supplemented with papain could replace part of high grade animal protein ingredients in weaned piglet feed. The results showed that Km, optimal pH and temperature of papain were 6.6875 mg/mL, 7.0° and 55°C respectively. It had a good stability when either pH ranged from 5.0 to 9.0 or temperature ranged from 4 to 65°C. The addition of papain at 75 mg/kg level significantly increased in vitro crude protein digestibility of soybean meal and piglet feed. Piglets (300; (Pietrain×Duroc)× (Landrace×Yorkshire)) weaned at 21±1 days with an initial body weight (BW) of 5.92±0.47 kg were assigned by BW, sex, and litter according to a randomized complete block design. The animal trial consisted of 5 dietary treatments with 6 replicates/treatment and 0 piglets/replicate. The dietary treatments were positive control (PC), negative control (NC), NC + 50 mg/kg papain, NC + 75 mg/kg papain, and NC +00 mg/kg papain. The results showed that papain significantly decreased diarrhea incidence of piglets fed the diets containing high level of soy-source protein material. There was a linearly improved apparent crude protein digestibility with the increasing dosage of protease. In conclusion, papain supplementation could be considered as an effective solution to break the inclusion limit of soybean source protein ingredients in weaned piglet diet.