This study was conducted to determine the effects of dietary protein level and supplementation of protease on growth performance, nutrient digestibility, gut microflora, intestinal morphology and fecal noxious gas emission in weanling pigs. A total of 240 weaned pigs (Landrace×Yorkshire×Duroc, 5.82±0.3 kg) were used during 4 weeks in 2 phases (days 0-14, phase 1; and days 15-28, phase 2) feeding program based on age and initial body weight. Pigs were allocated to 2×2 factorial arrangement, including 2 protein levels (HP, high protein; LP, low protein) and 2 protease levels (with or without protease). The average daily gain in the LP treatment (357 g/d) was increased rather than the HP treatment (339 g/d). A greater avarage daily gain was observed in dietary suppiemented protease treatment (358 vs 339 g/d). Average feed intake was greater in the LP treatment (544 g/d) rather than the HP treatment (530 g/d). A greater average daily feed intake was observed in dietary supplemented protease treatment (552 vs 523 g/d). Dry matter and crude protein digestibility were increased in dietary supplemented protease treatment (82.62% and 76.08%, respectively) rather than non-supplemented treatment (81.74% and 75.13%, respectively). Ileal Lactobacillus spp. count increased in dietary supplemented protease treatment (7.42 vs 7.32 log10CFU/g). Emission of H2S was decreased in the LP treatment (4.41 ppm) rather than HP treatment (4.78 ppm). Emission of NH3 was decreased in dietary supplemented protease treatment (10.43 ppm vs 11.76 ppm). In conclusion, the decrease of dietary protein level and supplementation of protease had beneficial effects on growth performance, nutrient digestibility, gut microflora, and noxious gas emission in weanling pigs.

A study was investigated the effects of the probiotic mixture (PM) contained Lactobacillus plantarum (L. plantarum) SY-99 2.4×109 CFU/kg and Bacillus subtilis (B. subtilis) SJ-61 2.2×109 CFU/kg on growth performance and fecal microflora counts of broiler chickens. Referred to the previous studies, a total of 160 one-day-old male broiler chicken (Ross 308) were randomly assigned to four experimental groups, which were a basal diet alone (control) and supplemented with PM 0.1 g/kg feed (T1), PM 0.2 g/kg feed (T2), and PM 0.4 g/kg feed (T3). After 28 days of administration, the average daily feed intake of T1 and T3 was significantly different compared to that of control (p<0.05). In addition, the feed conversion ratio of T2 and T3 was significantly improved compared to that of control (p<0.05). On the 28th day after administration, all treatment groups were significantly increased fecal lactic acid bacteria (LAB) counts and decreased fecal Enterobacteriaceae (ENT) counts compared to T1 (p<0.05). The results of this study indicated that the combination of L. plantarum and B. subtilis strains in the range of 0.2-0.4 g/kg feed could be used for the improvement of growth performance and fecal microflora in broiler chickens.