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±0.12 kg) 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±0.38 kg vs 25.75±0.39 kg; p<0.05) and average daily gain (491±7.40 g vs 460±7.46 g; p<0.05) in PROT fed pigs were increased significantly, but gain per feed (0.700±0.01 vs 0.678±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%±0.65% vs 81.21%±1.13% dry matter and 84.02%±0.52% vs 80.47%±1.22% nitrogen) and decreased (p<0.05) NH3 emission (2.0±0.16 ppm vs 1.2±0.12 ppm) 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 NH3 emission, thus, potentially serving as a tool in lowering noxious gas contribution of livestock production in the environment.

Volatility in feed ingredient prices prompts animal nutritionists to evaluate alternative methods to control feed costs. The objective of this study was to evaluate the effects of protease in growing pigs fed either high or low-density diets. A total of 140 pigs [(Landrace×Yorkshire)×Duroc] were used in a 6-wk study with an initial BW of 24.1 ± 0.02 kg equally distributed in 7 pens per treatment fed one of the following treatments: High-density diet with 3400 kcal ME/kg, 19.5% CP, and 0.85% SID Lys; High-density diet + 125 g/t Jefo Protease (Jefo, Canada); Low-density diet with 3300 kcal ME/kg, 17.6% CP, and 0.83% SID Lys; and Low-density diet + 125 g/t Jefo Protease. Diets were corn, soybean meal-based with 12% rice bran and 8% wheat bran. Data were subjected to statistical analyses as a completely randomized design using a 2 × 2 factorial arrangement with pen as the experimental unit. Differences among treatment means were determined using Duncan’s multiple range test with level of significance at P ≤ 0.05. High-density diets (P = 0.01) and protease supplementation (P = 0.05) significantly improved G:F in pigs (Table 1) compared to low-density diets and no protease supplementation. NH3 and H2S gas emission tended to be lower (P ≤ 0.10) in diets supplemented with protease. There were no statistical differences (P > 0.10) in initial weight, final weight, ADG, and ADFI. In conclusion, protease supplementation and high density diets improved G:F in 25- to 55-kg pigs.