不同精粗比全混合饲粮对肥育羔羊消化道pH和消化酶活性的影响

Influences of Total Mixed Diets with Different Concentrate-Roughage Ratio on pH and Activity of Digestive Enzymes in Alimentary Canal of Fattening Lambs

为研究饲粮精粗比对瘤胃液VFA浓度、胃肠道各段pH和消化酶活性的影响,将24只3-5月龄的无角陶赛特（♂）×（小尾寒羊×滩羊）（♀）断奶公羔（平均体质量25.83±6.14 kg）按同质原则分成3组（各8只）;正试期（40 d）分别饲喂精粗比为65：35（A）、50：50（B）、35：65（C）,相应消化能和粗蛋白水平为1.0、0.9、0.8倍NRC推荐量的全混合饲粮,正试期末每组屠宰6只羔羊,用于取样、测定。结果表明：（1）A处理羔羊瘤胃液总VFA（TV-FA）浓度显著高于B、C处理（P〈0.05）。（2）饲粮精粗比显著影响羔羊瘤胃液、空肠后段黏膜（7.03、7.31、7.35）及内容物（7.19、7.30、7.58）与回肠内容物（7.16、7.33、7.57）的pH（P〈0.05）。（3）各处理羔羊瘤胃液乙酸和丙酸摩尔比介于0.612-0.654与0.185-0.190之间,乙/丙酸比变动范围为3.38-3.57。（4）小肠各部分各种消化酶活性随营养水平的变化不一致。（5）小肠内容物糜蛋白酶、黏膜与内容物脂肪酶的最高活性均出现在空肠中段,内容物胰蛋白酶最高活性是在空肠后段,空肠后段与十二指肠内容物的α-淀粉酶活性均较高。结果表明,饲喂高精粗比全混合饲粮时瘤胃仍保持乙酸发酵类型;饲粮精粗比影响瘤胃、皱胃内容物与小肠后部黏膜及内容物的pH;十二指肠中具有较高的α-淀粉酶活性。

This study was conducted to investigate the effects of concentrate-roughage ratio in diets on concentration of VFA in rumen liquid,pH and digestive enzyme activities in different sections of alimentary canal.The twenty four crossbred weaned male lambs of Poll Dorset（♂）×（Tan-sheep × Small Tailed Han sheep）（♀） weighing（25.83±6.14） kg at the age of 3–5 months were divided similarly into three groups.They were fed on the diets with concentrate-roughage ratio of 65∶35（A）,50∶50（B）and 35∶65（C）（digestible energy and crude protein were at 1.0,0.9 and 0.8 times of NRC recommendation） respectively during the 40 days of regular experimental periods.Six lambs from each group were slaughtered for sampling at the end of regular feeding periods.The results showed that：（1） Concentration of total VFA（TVFA） in rumen liquid of lambs from group A was obviously higher than those from group B and C（P〈0.05）.（2） The pH of rumen liquid,homogenates of mucosa（7.03,7.31 and 7.35） and contents（7.19,7.30 and 7.58） in behind-jejunum,and of contents in ileum（7.16,7.33,7.57） were affected significantly by the concentrate-roughage ratio of diets（P〈0.05）.（3）Molar proportions of acetic acid and propionic acid were ranged from 0.612 to 0.654 and from 0.185 to 0.190 respectively,the acetic / propionic ratios varied ranging from 3.38 to 3.57.（4） There were non-uniform pattern ranked of activities of various digestive enzyme along small intestine with concentrate-roughage ratio of the diets.（5）The highest activities of chymotrypsin in content and those of lipase in mucosa homogenate and content occurred in the middle-jejunum,activity of trypsinase in contents of behind-jejunum was the highest,and the highest activities of α-amylase were noted in content of duodenum and behind-jejunum.It was concluded that still acetic acid pattern of rumen fermentation was kept in lambs fed total mixed diet with higher concentrate-roughage ratio;the pH of contents in rumen and abomasums,of mucosa and contents in behind section of small intestine were affected by the concentrate-roughage ratio of the diets;there was also higher activity of α-amylase in duodenum.