日粮碳水化合物平衡指数对山羊消化道酶活性和养分瘤胃降解率的影响
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摘要
本研究以山羊为试验动物,通过调节日粮玉米和青贮的含量,以调控日粮的碳水化合物平衡指数(CBI),研究CBI对瘤胃和小肠酶活性和养分瘤胃降解率的影响,确定CBI对饲料养分降解的作用机理和影响规律,并确定其推荐标准。主要的研究结果如下:
1.选取4只安装十二指肠瘘管的成年山羊,采用4×4拉丁方试验设计,测定不同精粗比日粮的CBI值。4种日粮的精粗比分别为72:28、52:48、32:68和12:88。瘤胃养分降解率以盐酸不溶灰分作为指示剂。结果显示,4种试验日粮的CBI分别为0.42、0.83、1.42和2.48。
2.选取4只安装瘤胃瘘管的成年山羊,采用4×4拉丁方试验设计,利用瘤胃尼龙袋法测定CBI对瘤胃养分降解率的影响。4种试验日粮的CBI分别为0.42、0.83、1.42和2.48。结果表明,CBI为0.42的日粮,瘤胃液木聚糖酶和晶体纤维素酶活性低于CBI为0.83～2.48的日粮,α-淀粉酶活性随CBI的提高而线性下降,蛋白酶和脲酶活性不受影响;CBI为0.42日粮,苜蓿干草的DM和NDF有效降解率显著低于1.42和2.48组,0.83组介于中间;随日粮CBI提高,玉米和豆粕的DM、淀粉和CP有效降解率呈先提高后下降的趋势变化,CBI为0.83组的降解率最高。
3.选取4只安装总胆管插管的成年山羊,采用4×4拉丁方试验设计,研究CBI对胰腺外分泌功能的影响。4种试验日粮的CBI分别为0.42、0.83、1.42和2.48。结果表明,随日粮CBI的提高,胰胆汁分泌量、胰蛋白酶和糜蛋白酶总分泌活性不受影响,胰腺α-淀粉酶和脂肪酶总分泌活性呈先提高后下降的趋势变化,CBI为0.83组α-淀粉酶和脂肪酶分泌量最高。
综合考虑瘤胃液酶活性和胰腺消化酶分泌量,以及瘤胃NDF、淀粉和CP的有效降解率,山羊日粮的CBI以0.83为宜。
Three experiments were taken to evaluate effects of Carbohydrate Balance Index (CBI), by altering dietary corn and silage content, on digestible enzyme activities in gastrointestinal tract and rumen nutrient degradability of goats. The objective was to investigate the mechanism, influence and recommendation of CBI in adult goats. The main results are as follows:
1. Four goats surgically fitted with duodenal cannulas were used in 4×4 Latin square design to measure CBI of diets containing different concentrate and forage. Results have shown that dietary CBI was 0.42, 0.83, 1.42 and 2.48, respectively.
2. Four goats surgically fitted with ruminal cannulas were used in 4×4 Latin square design and randomly fed diets having CBI of 0.42, 0.83, 1.42 and 2.48 to determine the effects of CBI on enzyme activities and rumen nutrient degradability. Results have shown that ruminal fiber degradability and cellulase activity in the rumen fluid increased linearly to a point between 0.83 and 1.42 of CBI, after which further increase was not observed with increasing CBI in goats. Increasing CBI results in a quadratic increase in ruminal degradability of starch and protein.
3. Four goats surgically fitted with common bile duct catheter were used in 4×4 Latin square design to determine the effects of CBI on pancreatic exocrine secretion in goats. Periods consisted of 10 d of adaptation followed by 3 d of sample collection. Juice was collected in 1-h fractions continuously for 72 h. Total juice secreted was recorded, and 3% subsamples were retained to form a composite sample. The remaining fluid was returned to the duodenum. Juice composite samples were analyzed for activities ofα-amylase, trypsin, chymotrypsin and lipase. Total secretion of juice, trypsin and chymotrypin was not affected by CBI. Increasing CBI results in a quadratic increase in pancreaticα-amylase and lipase secretion. Maximum secretion ofα-amylase and lipase is reached when CBI is 0.83 in adult goats.
These results indicate that the optimal CBI is 0.83 for goats regarding enzyme activities and nutrient degradability.
1.选取4只安装十二指肠瘘管的成年山羊,采用4×4拉丁方试验设计,测定不同精粗比日粮的CBI值。4种日粮的精粗比分别为72:28、52:48、32:68和12:88。瘤胃养分降解率以盐酸不溶灰分作为指示剂。结果显示,4种试验日粮的CBI分别为0.42、0.83、1.42和2.48。
2.选取4只安装瘤胃瘘管的成年山羊,采用4×4拉丁方试验设计,利用瘤胃尼龙袋法测定CBI对瘤胃养分降解率的影响。4种试验日粮的CBI分别为0.42、0.83、1.42和2.48。结果表明,CBI为0.42的日粮,瘤胃液木聚糖酶和晶体纤维素酶活性低于CBI为0.83～2.48的日粮,α-淀粉酶活性随CBI的提高而线性下降,蛋白酶和脲酶活性不受影响;CBI为0.42日粮,苜蓿干草的DM和NDF有效降解率显著低于1.42和2.48组,0.83组介于中间;随日粮CBI提高,玉米和豆粕的DM、淀粉和CP有效降解率呈先提高后下降的趋势变化,CBI为0.83组的降解率最高。
3.选取4只安装总胆管插管的成年山羊,采用4×4拉丁方试验设计,研究CBI对胰腺外分泌功能的影响。4种试验日粮的CBI分别为0.42、0.83、1.42和2.48。结果表明,随日粮CBI的提高,胰胆汁分泌量、胰蛋白酶和糜蛋白酶总分泌活性不受影响,胰腺α-淀粉酶和脂肪酶总分泌活性呈先提高后下降的趋势变化,CBI为0.83组α-淀粉酶和脂肪酶分泌量最高。
综合考虑瘤胃液酶活性和胰腺消化酶分泌量,以及瘤胃NDF、淀粉和CP的有效降解率,山羊日粮的CBI以0.83为宜。
Three experiments were taken to evaluate effects of Carbohydrate Balance Index (CBI), by altering dietary corn and silage content, on digestible enzyme activities in gastrointestinal tract and rumen nutrient degradability of goats. The objective was to investigate the mechanism, influence and recommendation of CBI in adult goats. The main results are as follows:
1. Four goats surgically fitted with duodenal cannulas were used in 4×4 Latin square design to measure CBI of diets containing different concentrate and forage. Results have shown that dietary CBI was 0.42, 0.83, 1.42 and 2.48, respectively.
2. Four goats surgically fitted with ruminal cannulas were used in 4×4 Latin square design and randomly fed diets having CBI of 0.42, 0.83, 1.42 and 2.48 to determine the effects of CBI on enzyme activities and rumen nutrient degradability. Results have shown that ruminal fiber degradability and cellulase activity in the rumen fluid increased linearly to a point between 0.83 and 1.42 of CBI, after which further increase was not observed with increasing CBI in goats. Increasing CBI results in a quadratic increase in ruminal degradability of starch and protein.
3. Four goats surgically fitted with common bile duct catheter were used in 4×4 Latin square design to determine the effects of CBI on pancreatic exocrine secretion in goats. Periods consisted of 10 d of adaptation followed by 3 d of sample collection. Juice was collected in 1-h fractions continuously for 72 h. Total juice secreted was recorded, and 3% subsamples were retained to form a composite sample. The remaining fluid was returned to the duodenum. Juice composite samples were analyzed for activities ofα-amylase, trypsin, chymotrypsin and lipase. Total secretion of juice, trypsin and chymotrypin was not affected by CBI. Increasing CBI results in a quadratic increase in pancreaticα-amylase and lipase secretion. Maximum secretion ofα-amylase and lipase is reached when CBI is 0.83 in adult goats.
These results indicate that the optimal CBI is 0.83 for goats regarding enzyme activities and nutrient degradability.
引文
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