The experiment was conducted to study the effects of different sources of vegetable oil on ruminal fermentation and microbial enzyme activities in sheep fed diets with equal level of linoleic acid. Four healthy crossbred male sheep[(Northeast semi-fine wool × Dorset sheep, (40 ± 1 ) kg ] fitted with cannulas were used in a 4 × 4 Latin square design. The experiment was divided into 4 periods with 16 d per period. The sheep were assigned to a control group (no addition) and 3 exprimental groups [group PO (4.00％ peanut oil), group CO (2.84％ corn oil) and group SO (2.86％ soybean oil)]. The linoleic acid level of the 3 expermental groups was equal. The dynamic variations of pH, protozoa count, NH3-N concentration and volatile fatty acid (VFA) concentration in 24 h as well as microbial enzyme activites in the rumen fluid were determined. The results showed as follows: there were no significant effects of different sources of vegetable oil on the mean of pH,NH3-N concentration and VFA concentration ( P＞0.05 ); the total volatile fatty acid (TVFA) concentration and protozoa count of group PO were significantly lower than those of the control group 1 to 4 h after ingestation ( P＜0.05 ); the activities of filter paper cellulase (FPase), carboxymethyl cellulose enzyme (CMCase), glucosidase and pectinase of group PO were significantly decreased 1 to 4 h after ingestation ( P ＜0.05); there was no significant effect of different sources of vegetable oil on xylanase activity ( P ＞ 0.05 ). There was no negative influence of different sources of vegetable oil on ruminal fermentation in sheep fed diet with equal level of linoleic acid; supplemention of 4.00％ peanut oil decreaed the activities of ruminal fiber degradation related enzymes, in which the activities of CMCase, pectinase, FPase and glucosidase were significantly decreased 1 to 4 h after ingestation.[Chinese Journal of Animal Nutrition,2011, 23(5) :748-754]%本试验旨在研究饲粮中相同亚油酸水平下,不同植物油对绵羊瘤胃发酵和微生物酶活性的影响.选取4只雄性、健康、体重(40±1)kg、安装有永久性瘤胃瘘管的绵羊(东北半细毛羊×陶赛特羊).采用4×4拉丁方试验设计,整个试验分4期,每期16 d.按采食的饲粮中添加的不同植物油将试羊分为对照组(无添加)和3个试验组[PO组(4.00%花生油)、CO组(2.84%玉米油)和sO组(2.86%大豆油)],3个试验组亚油酸水平一致.测定24 h内瘤胃液pH、原虫数、氨态氮浓度和挥发性脂肪酸浓度变化以及微生物酶活性.结果表明:饲粮中不同植物油对瘤胃液pH、氨态氮浓度、挥发性脂肪酸浓度平均值没有显著影响(P＞0.05);在每次采食后1～4 h,PO组的总挥发性脂肪酸浓度、原虫数量显著低于对照组(P＜0.05);每次采食后1～4 h,PO组的滤纸纤维素酶、羧甲基纤维素酶、葡萄糖苷酶和果胶酶活性显著降低(P＜0.05);饲粮中不同植物油后对木聚糖酶活性无显著影响(P＞0.05).在饲粮相同亚油酸水平下,不同植物油(添加量2.84%～4.00%)对羊瘤胃发酵没有不利影响;4.00%花生油的添加使瘤胃纤维降解相关酶的活性降低,其中羧甲基纤维素酶、果胶酶、滤纸纤维素酶和葡萄糖苷酶活性在采食后1～4 h显著降低.
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