Performance Responses, Nutrient Digestibility, Blood Characteristics, and Measures of Gastrointestinal Health in Weanling Pigs Fed Protease Enzyme

Although exogenous protease enzymes have been used in poultry diets quite extensively, this has not been the case for pig diets. In general, due to their better gut fermentative capacity and longer transit time, pigs have greater capacity to digest dietary proteins than poultry. However, in early-weaned piglets, the stress brought about by weaning adversely affects the digestion of dietary proteins. Therefore, a study was conducted to determine the effects of a commercial protease enzyme in weanling pigs. Indices of growth, nutrient digestibility, blood profiles, fecal microflora, fecal gas emission and fecal scores were measured during the study. A total of 50 weanling pigs ($6.42{\pm}0.12kg$) at 28 d of age were randomly assigned to receive 1 of 2 dietary treatments: i) control diet (corn-soy based) with no supplemental protease (CON), and ii) control diet+200 g/ton protease (PROT) for 42 d. A completely randomized design consisting of 2 treatments, 5 replicates, and 5 pigs in each replicate was used. Growth performance in terms of body weight ($27.04{\pm}0.38kg$ vs $25.75{\pm}0.39kg$; p<0.05) and average daily gain ($491{\pm}7.40g$ vs $460{\pm}7.46g$; p<0.05) in PROT fed pigs were increased significantly, but gain per feed ($0.700{\pm}0.01$ vs $0.678{\pm}0.01$; p>0.05) was similar between treatments at d 42. Relative to CON pigs, PROT fed pigs had increased (p<0.05) apparent total tract digestibility ($84.66%{\pm}0.65%$ vs $81.21%{\pm}1.13%$ dry matter and $84.02%{\pm}0.52%$ vs $80.47%{\pm}1.22%$ nitrogen) and decreased (p<0.05) $NH_3$ emission ($2.0{\pm}0.16ppm$ vs $1.2{\pm}0.12ppm$) in the feces at d 42. Except for a decreased (p<0.05) in blood creatinine level, no differences were observed in red blood cell, white blood cell, lymphocyte, urea nitrogen, and IgG concentrations between treatments. Fecal score and fecal microflora (Lactobacillus and E. coli) were also similar between CON and PROT groups. Overall, the supplementation of protease enzyme in weanling pigs resulted in improved growth rate and nutrient digestibility. Exogenous protease enzyme reduced fecal $NH_3$ emission, thus, potentially serving as a tool in lowering noxious gas contribution of livestock production in the environment.