Application Research On Alpha-galactosidase In Cornsoybean Meal-based Diet For Weaned Piglets

The paper was conducted to study on the effects of alpha-galactosidase on performance, fecal microorganism,serum biochemistry indices and nutrient apparent digestibility in corn- soybean meal diet of piglet, moreover, evaluation for the alpha-galactosidase had been researched with in vitro digestion method using the dialysis tubing.Exp.1:To study the effects of alpha-galactosidase on growth performance, ninety healthy,37-day-old (30-day-old weaned) Landrace×Yorkshinepiglets with similar body weight (11.05±1.97 kg)were selected. According to the same source and the similar initial weight principles, completely randomize design was adopted in this experiment, and the piglets were randomly divided into5groups, each group will include 3 replicates of 6 pigs each(half male and half female). Group I was control group, feeding with corn- soybean meal basic diet without alpha-galactosidase;Ⅱ,Ⅲ,IV,V were test groups, which added different levels (20U/,30U/t,40U/t,50U/t) of alpha-galactosidase to the basic diet respectively. The results suggested that: the growth performance of piglets were improved in some extents when the corn-soybean meal basic diet was supplemented with different levels of alpha-galactosidase.Among them, test groupIVwith the optimal growth performance, compared with control group I, test group II, test groupIII, test groupⅤ, the average daily gain(ADG) of test groupⅣwas respectively increased by16.13%,9.09%,2.86%,2.86%, but not significant each other (P> 0.05)Exp.2:The sample collected in feeding experiment were done laboratory analysis furtherly. Including:(1) Determineing the fecal microorganism:On the 28d and 29d of the feeding experiment, one piglet(healthy) was randomly choosed from each replicates to collect feces from anus. The samples were collected in pouch without any bacterium -s(temporarily conserved at 4℃), plate colony counting method was adopted to determine escherichia coli and lactobacilli; (2)Determineing the serum biochemistry indices:When feeding experiment is finished (after weighing on an empty stomach), two piglets whose body weight close to average body weight and in good health will be choosed from every replicate. Preca -val blood sampling 8ml, then centrifugate, collect the upper serum. Determineing 3,5,3'-triiodothyronine (T3), thyroxine(T4),growth hormone(GH),urea nitrogen(BUN),total protein (TP),blood sugar(GLU),IgM and IgG;(3)Nutrient apparent digestibility:Acid insoluble ash(AIA) method was adopted. On the27d,28d and 29d of the feeding experiment, feces were collected from each pen, then convention nutritional apparent digestibility were determi-ned. The results indicated that:(1)Alpha-galactosidase can reduce the number of escherichia coli, and increase the number of lactobacilli (P> 0.05);(2) Alpha-galactosidase can increase the contents of TP, IgG, T3, T4, GH, reduce the contents of BUN.Compared with control group I, the contents of IgG, T4 of test IV was respectively increased by 8.30%,18.37%, but BUN reduced by 26.18%;(3)Alpha-galactosidase can increase the apparent digestibility of crude fiber(P<0.05),crude fat,crude protein,energy,compared. with control groupⅠ,the apparent digestibility of crude fiber of testⅣwas increased by26.42%(P<0.05).Exp.3:After determineing the in vitro digestibility parameter(enzyme concentration, pH, action time) of pepsin-trypsin two steps digestion method, in order to evaluate the effects of alpha-galactosidase, the diets of feeding.test and regular soybean meal were digested in vitro by dialysis tube. The results indicated that:(1) Under this experiment conditions, the optimal concentration of pepsin is 3.0mg/ml, the optimal pH of pepsin is 1.8, the optimal action time of pepsin is 4h; and the optimal concentration of trypsin is 3.0mg/ml, the optimal pH of trypsin is 7.6, the optimal action time of trypsin is 24h.(2)Alpha-galactosidase can increase the in vitro digestibility of dry matter(DM),crude protein (CP)and energy(E) of corn- soybean meal diets, the best isⅣ, it's in vitro digestibility of dry matter(DM),crude protein (CP)and energy(E) was 10.01%,4.65%and2.68% greater than control group respectively. When alpha-galactosidase was added to soybean meal, the in vitro digestion was better than in diet,and when alpha-galactosidase was 0.3U/kg,the digestibility of crude protein (CP) was highest. (3)By applicating of the regression analysis between in vitro digestibility of diet,in vivo digestibility of diet and average daily gain, we fund that the in vivo (Y) and in vitro(X) digestibility of dry matter had strong positive correlation (r= 0.888,P=0.022), regression equation was Y=0.6077X+56.175 (R2=0.7888,P= 0.044<0.05,n=5);the in vitro digestibility of dry matter(X) and average daily gain (Y) had strong positive correlation (r=0.898, P=0.019),regression equation was Y=0.0113X-0.1245 (R2=0.8072, P=0.038<0.05, n=5).The results of in vitro digestion, in vivo digestion and feeding experiment were considerably similar, it indicated that the effects of alpha-galactosidase could be evaluated and predicted by in vitro digestion experiment using the dialysis tubing.