Energy values evaluation and improvement of soybean meal in broiler chickens through supplemental mutienzyme

ABSTRACT: This study measured the metabolizable energy of soybean meal (SBM) and evaluated effects of soybean meal specific enzymes supplementation in corn-soybean diets on growth performance, intestinal digestion properties and energy values of 28-day-old broilers. A total of 336 one-day-old male AA broiler chickens were distributed to 7 groups in a completely random design. The birds were given 7 diets containing 6 diets with different combined soybean meals and a fasting treatment, 8 replicates per treatment and 6 birds per replicate (Trial 1). A total of 672 one-day-old male AA broiler chickens were randomly allocated to 7 dietary treatments including a control diet and 6 diets supplemented with 300 mg/kg α-galactosidase, 200 mg/kg β-mannanase, and 300 mg/kg protease individually or in combination (Trial 2). Apparent metabolizable energy (AME) of broilers was measured from d 25 to 27 in both trial 1 and trial 2. The results showed that AME values of combined soybean meals averaged 2,894 kcal/kg. Dietary β-mannanase and protease supplementation increased body weight gain (P < 0.05) during d 0 to 14, whereas did not affect the growth performance (P > 0.05) during d 14 to 28. Addition of β-mannanase in combination with other enzymes significantly increased lipase and trypsin content (P < 0.05) in ileum. In addition, dietary β-mannanase and protease supplementation individually or in combination enhanced trypsin enzyme content in jejunum (P < 0.05). The β-mannanase enzyme enhanced villus height and villus height to crypt depth ratio (P < 0.05) of ileum compared with control diet. Moreover, supplementation of enzyme except for protease enhanced raffinose and stachyose degradation ratio (P < 0.05). Dietary β-mannanase supplementation individually or in combination enhanced AME and AMEn values (P < 0.05). This study demonstrated that dietary enzyme supplementation especially β-mannanase improved intestinal digestion properties and contributed to high energy values.