本文旨在研究饲粮蛋白质水平对冬毛期水貂胃肠道消化酶活性以及空肠形态结构的影响。选择90日龄的健康公貂60只,随机分成6组(每组10个重复,每个重复1只),分别饲喂蛋白质水平为28%(Ⅰ组)、30%(Ⅱ组)、32%(Ⅲ组)、34%(Ⅳ组)、36%(Ⅴ组)和38%(Ⅵ组)的试验饲粮。预试期7 d,正试期115 d。饲养试验结束后进行屠宰,制备胃肠道内容物上清液,用于测定消化酶活性;制备空肠组织切片,用于观察空肠的形态结构。结果表明:Ⅴ组水貂的胃蛋白酶活性极显著高于Ⅰ、Ⅱ和Ⅲ组(P<0.01),与Ⅳ和Ⅵ组差异不显著(P>0.05)。Ⅳ组水貂的十二指肠和空肠胰淀粉酶活性极显著高于Ⅰ、Ⅱ、Ⅲ、Ⅴ和Ⅵ组(P<0.01)。Ⅳ和Ⅴ组水貂的回肠胰淀粉酶活性显著或极显著高于Ⅰ和Ⅱ组(P<0.05或P<0.01)。Ⅳ组水貂的十二指肠胰蛋白酶活性极显著高于Ⅰ、Ⅱ、Ⅴ和Ⅵ组(P<0.01),空肠胰蛋白酶活性极显著高于Ⅰ、Ⅱ、Ⅲ、Ⅴ和Ⅵ组(P<0.01)。Ⅲ组水貂的回肠胰蛋白酶活性显著高于Ⅵ组(P<0.05),与其他各组差异不显著(P>0.05)。Ⅵ组水貂的十二指肠胰脂肪酶活性显著或极显著高于Ⅱ、Ⅳ和Ⅴ组(P<0.05或P<0.01),空肠胰脂肪酶活性显著或极显著高于Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅴ组(P<0.05或P<0.01)。Ⅰ、Ⅲ和Ⅴ组水貂的回肠胰脂肪酶活性极显著高于Ⅱ和Ⅵ组(P<0.01),与Ⅳ组差异不显著(P>0.05)。饲粮蛋白质水平为36%时,水貂空肠绒毛高度、隐窝深度、绒毛高度与隐窝深度比值、黏膜厚度以及肠壁厚度均处在较高水平。由此得出,饲粮蛋白质水平可影响冬毛期水貂胃肠道消化酶活性,并可调节其空肠形态结构。

The purpose of this experiment was to study the effects of dietary protein level on gastrointestinal digestive enzyme activity and jejunal morphology in minks during winter hair period. Sixty healthy male minks at 90 days of age were randomly divided into 6 groups with 10 replicates in each group, and 1 mink in each replicate. The minks in the 6 groups were fed experimental diets containing different levels of protein, which were 28% (groupⅠ), 30% (group Ⅱ), 32% (group Ⅲ), 34% (group Ⅳ), 36% (group Ⅴ) and 38% (group Ⅵ), respectively. There was a 7-day pretrial period followed by a 115-day experimental period. The minks were slaughtered at the end of the feeding experiment. The supernatant of gastrointestinal content was prepared to determine the digestive enzyme activity, and the jejunal tissue section was prepared to observe the jejunal morphology. The results showed as follows: the pepsin activity in the group Ⅴ was significantly higher than that in the groups Ⅰ, Ⅱ and Ⅲ (P<0.01), but no significant difference was found compared with the groups Ⅳ and Ⅵ (P>0.05). The amylopsin activity of duodenum and jejunum in the group Ⅳ was significantly higher than that in the groups Ⅰ, Ⅱ, Ⅲ, Ⅴ and Ⅵ (P<0.01). The amylopsin activity of ileum in the groups Ⅳ and Ⅴ was significantly higher than that in the groups Ⅰ and Ⅱ (P<0.05 or P<0.01). The trypsinase activity of duodenum in the group Ⅳ was significantly higher than that in the groups Ⅰ, Ⅱ, Ⅴ and Ⅵ (P<0.01), and that of jejunum in the group Ⅳ was significantly higher than that in the groups Ⅰ, Ⅱ, Ⅲ, Ⅴ and Ⅵ (P<0.01). The trypsinase activity of ileum in the group Ⅲ was significantly higher than that in the group Ⅵ (P<0.05), but no significant difference was found between group Ⅲ and other groups (P>0.05). The pancrelipase activity of duodenum in the group Ⅵ was significantly higher than that in the groups Ⅱ, Ⅳ and Ⅴ (P<0.05 or P<0.01), and that of jejunum in the group Ⅵ was significantly higher than that in the groups Ⅰ, Ⅱ, Ⅲ, Ⅳ and Ⅴ (P<0.05 or P<0.01). The pancrelipase activity of ileum in the groups Ⅰ, Ⅲ and Ⅴ was significantly higher than that in the groups Ⅱ and Ⅳ (P<0.01), but no significant difference was found compared with the group Ⅳ (P>0.05). The villus height, crypt depth, villus height to crypt depth ratio, mucosal thickness and intestinal wall thickness of jejunum all kept a higher level when dietary protein level was 36%. In conclusion, the dietary protein level can affect the digestive enzyme activity of gastrointestinal tract, and regulate the morphology of jejunum in minks during winter hair period.