Effect Of Dietary Starch Level On Activity Of Amylase And Gastroenteric Morphology In Goats

1. Effect of dietary starch level on starch digestibility and activity ofα-amylase in goatsThe objective of this experiment was to determine the effects of dietary starch level on starch digestibility and activity ofα-amylase in the pancreas and the digesta of small intestine in goats. Eighteen Guanzhong male goats aged 9 months (initial body weight 28.4±1.6kg) were assigned randomly to three dietary treatments (6goats/treatment) in a completely random design. Experimental diets were: (1) low starch level (LS); (2) medium starch level (MS) and (3) high starch level (HS), and contained 27.62%, 35.20%, 45.61% starch level respectively, the major starch source is corn grain ,which is cracked to pass through a 3-mm screen. Diets were formulated to contain similar crude protein and were fed twice daily for 35d. Dry matter intake was restricted to be similar (1.0 kg/d) among the treatments. After a 35d feeding period, goats were slaughtered, the digesta were collected from the rumen and small intestine to determin the starch digestibility andα-amylase activity, the pancreas were also collected to measure the weight andα-amylase activity. The results showed that disappearance amount of starch in rumen and small intestine were increased with increasing dietary starch level(P<0.05﹚. The weight of pancreas in goats fed MS diets significantly great when compared to goats fed LS and HS diets(P<0.05﹚. Increasing starch level can increase rumen escape starch and pancreasα-amylase activity.2. Effect of dietary starch level on gastroenteric morphology and digesta pH in goatsThe objective of this study was to determine the effects of dietary starch level on rumen and small intestinal morphology and pH in goats. Eighteen Guanzhong male goats aged 9 months (initial body weight 28.4±1.6kg) were assigned randomly to three dietary treatments (6goats/treatment) in a completely random design. Experimental diets were: (1) low starch level (LS); (2) medium starch level (MS) and (3) high starch level (HS), and contained 27.62%, 35.20%, 45.61% starch level respectively. After a 35d feeding period, goats were slaughtered to obtain rumen and small intestinal sample, and the pH of rumen liquid and small intestinal digesta were determined at the time of the goats were slaughtered. The ruminal pH in goats fed HS diets was significantly lower than goats fed LS and HS diets (P=0.05). In ventral ruminal sac, the papillae height for goats fed the MS diet was greater (P<0.05) compared with goats fed the LS and HS diets. Papillae surface for goats fed the MS diets was larger than goats fed LS diets, and the latter was greater than goats fed HS diets (P<0.05). In dorsal ruminal sac, goats fed the HS diets had lowest papillae height(P<0.05) compared with goats fed the LS and MS diets, papillae surface (P<0.05) for goats fed MS diets was larger than goats fed LS and HS diets. Villus height of jejunum in goats fed MS diets were significantly larger than goats fed LS and HS diets (P<0.05). This study indicated that dietary starch intake affect ruminal morphology and pH, high starch diet impaired the ruminal morphology development and reduced the ruminal pH, but dietary starch level did not affect the morphology and digesta pH of the small intestine.3. Effect of dietary starch level on performance and slaughtering characteristic in goatsThe objective of this experiment was to determine the effect of dietary starch level on performance and slaughtering characteristic in goats. Eighteen Guanzhong male goats aged 9 months (initial body weight 28.4±1.6kg) were assigned randomly to three dietary treatments (6goats/treatment) in a completely random design. Experimental diets were: (1) low starch level (LS); (2) medium starch level (MS) and (3) high starch level (HS), and contained 27.62%, 35.20%, 45.61% starch level respectively. The results indicated that the average daily gain (ADG)was increased as dietary starch level increased(P<0.05﹚. The weight of abomasum was significantly increased(P<0.05﹚in goats fed MS diets, the other visceral organ were not affected by dietary treatment(P>0.05﹚. Feed efficiency of HS group was significantly improved compare with the other two groups(P<0.05﹚.