Effects Of β-Glucosidase On The Growth Performance Of Finishing Pigs And Approach To The Mechanism

The experiments were conducted to study the hydrolysis condition of soybean isoflavone byβ-glucosidase, to evaluate the effect ofβ-glucosidase on the growth performance of finishing pigs, and to investigate the action mechanism involving digestibilities of feed nutrients, metabolism of lipid and bone, protein retention, antioxidation and immune function and so on.Experiment 1 Study on Optimal Hydrolyzation Parameters of soybean isoflavone byβ-glucosidase from Aspergillus niger: In order to optimizate the hydrolysis condition of soybean isoflavone byβ-glucosidase from Aspergillus niger, three-factor, five-level, quadratic regression general rotational combination design was used to establish the mathematics matrix between the isoflavone aglycones ratio and three factors including hydrolysis time, hydrolysis temperature and enzyme concentration. Results showed that the optimum hydrolytic conditions were the hydrolysis time 5.3h, hydrolysis temperature 55.4℃and enzyme concentration 68.7U/g.Experiment 2 Effects ofβ-glucosidase on the Growth Performance of Finishing Pigs and Approach to its Mechanism: In order to display the effects ofβ-glucosidase on the growth performance of finishing pigs, one hundred sixty finishing pigs (Duroc×Landrace×Yorkshine) with an average initial body weight of 60±2.35 kg were randomly assigned to 4 treatment groups (4 pens per group each with 10 finishing pigs per pen,) with 1 to 1 sex ratio. The finishing pigs received the maize-soybean basal diets supplemented with 0, 0.1, 0.2 and 0.3 g/Kgβ-glucosidase additive for the duration of 49 days.The results showed that average daily gain of finishing pigs supplemented with 0.1%, 0.2% and 0.3%β-glucosidase were 6.27% (P>0.05), 9.41%(P>0.05) and 10.33%(P <0.05) higher than that of control group respectively, the feed to gain ratios of finishing pigs were decreased by 7.48%( P>0.05),8.10%( P>0.05) and 10.90%(P<0.05) respectively, but there are no effect on the average daily feed intakes. The 0.3%β-glucosidase was the best level for feeding finishing pigs. It was showed by slaughter experiment that compared with control group, lean meat percentage of finishing pigs fed with 0.3%β-glucosidase increased by 25.85%(P<0.05), bone weight rate increased by 13.22%(P<0.05), carcass fat ration decreased 28.14%(P<0.05), back-fat thickness diminished 14.33%(P>0.05) while Loin muscle area, total fat content of subcutaneous adipose and weight rate of digestive organ had no significant change (P>0.05). Analysis of biochemical index indicated thatβ-glucosidase activity was gradually decreased when it passed alimentary tract. Furthermore,β-glucosidase significantly improved the apparent digestibilities of crude protein (CP) (P<0.05) and calcium (Ca) (P<0.05) while had little effect on the digestibilities of crude fat (EE), crude ash (CA) and phosphorus (P). However,β-glucosidase had no effect on the activity of amylase, lipase and trypsin in duodenum of finishing pigs. In addition, content of isoflavone aglycones, Ca and P in serum increased by 68.48%, 10.34% and 7.79% (P<0.05), respectively, while urea nitrogen (BUN) decreased by 14.38% (P<0.05). But activity of alkaline phosphatase (ALP) had no significant change. After supplementation withβ-glucosidase, triglyceride (TG3) and low density lipoprotein cholesterol (LDL-C) level decreased by 13.51% (P>0.05) and 20.8% (P<0.05), and high-density lipoprotein cholesterol (HDL-C) level increased by 15.2% (P<0.05) compared with control group. However, total cholesterol (TCH) and free fatty acid (FFA) level had no remarkable change. Moreover, superoxide dismutase (SOD) activity in serum and liver enhanced by 10.1% (P<0.05) and 15.33% (P<0.05), respectively, and content of serum malondialdehyde (MDA) diminished by 20.73% (P<0.05) while glutathione peroxidase (GSH-Px) showed no significant change. Interestingly,β-glucosidase had no remarkable effect on spleen weight rate and level of IgG, C3 and C4, but IgA and IgM content increased by 14.93% (P>0.05) and 15.89% (P>0.05). The level of serum testosterone (T), estrogen (E2) and growth hormone (GH) enhanced by 17.27% (P>0.05), 51.42% (P<0.01) and 34.86% (P<0.05), respectively.