饲粮中添加牛至精油和莫能菌素对荷斯坦犊牛血清生化指标、消化酶活性及瘤胃微生物区系的影响

旨在研究牛至精油（oregano essential oil，OEO）与莫能菌素（monensin，MON）对荷斯坦犊牛血清生化指标、消化酶活性以及瘤胃微生物区系的影响。本试验前期阶段选用了体重相近（（41.31±2.23）kg），体况良好的荷斯坦初生犊牛80头，随机分为4组，每组20头，采用单栏饲养。对照组饲喂全脂牛乳和颗粒饲料，其他3个试验组在饲喂全脂牛乳和颗粒饲料的基础上分别添加4 g·kg^-1牛至精油、3.6 g·kg^-1莫能菌素和7.6 g·kg^-1牛至精油和莫能菌素的混合物，饲喂至56、70日龄时，从每组中选取6头体重相近的公犊，颈静脉采血测定血清指标，并通过口腔导管的形式采集犊牛的瘤胃液，检测消化酶活性以及瘤胃微生物区系。结果表明：1）添加牛至精油显著提高了56日龄犊牛血清中TP、SOD、GSH和GSH-Px的浓度（P ≤ 0.05）；莫能菌素对56、70日龄犊牛BUN浓度有降低的趋势（P<0.10）。2）牛至精油显著降低了56、70日龄犊牛瘤胃中产琥珀酸丝状杆菌的数量（P<0.05），显著提高了白色瘤胃球菌的数量（P ≤ 0.05）；莫能菌素显著降低了56、70日龄犊牛瘤胃中原虫的数量（P ≤ 0.05），并有降低白色瘤胃球菌数量的趋势（P<0.10），在56日龄时，莫能菌素有降低犊牛瘤胃中黄色瘤胃球菌数量的趋势（P<0.10）；牛至精油和莫能菌素对56、70日龄犊牛瘤胃中溶纤维丁酸弧菌有显著的交互作用（P ≤ 0.05）；在56日龄时，牛至精油和莫能菌素对栖瘤胃普雷沃氏菌有交互作用的趋势（P<0.10），而在70日龄时则呈显著的交互作用（P ≤ 0.05）。3）牛至精油和莫能菌素对56、70日龄犊牛瘤胃中胃蛋白酶浓度有显著的交互作用（P ≤ 0.05）。综上所述，饲粮中添加牛至精油可提高犊牛的免疫力和抗氧化能力。莫能菌素在抑制瘤胃内原虫数量上强于牛至精油，牛至精油对提高主要蛋白质降解菌数量的作用效果优于莫能菌素。总之，牛至精油可改善犊牛的健康状况以及调控瘤胃微生物区系，牛至精油作为天然植物抗生素可替代犊牛期预防性治疗的其他类抗生素生长促进剂。

Effects of Oregano Essential Oil and Monensin in Diet on Serum Biochemical Parameters,Digestive Enzyme Activities and Ruminal Microflora of Holstein Calves

The purpose of this study was to examine the effects of oregano essential oil (OEO) and monensin (MON) on serum biochemical parameters, digestive enzyme activities and ruminal microflora of Holstein calves. Eighty Holstein calves ((41.31±2.23)kg) were randomly divided into 4 treatments and with 20 calves each. The calves in control treatment were fed with whole milk and pellet feed. The calves in other treatments were fed with whole milk and pellet feed, and supplementation with 4 g·kg^-1 OEO, 3.6 g·kg^-1 MON and a mixture of 7.6 g·kg^-1 OEO and MON, respectively. At 56 and 70 days of age, six male calves were selected from each treatment with similar body weight, blood samples from the jugular vein were collected from each calf to determine serum biochemical parameters and rumen fluid was collected by oral catheter to determine digestive enzyme activities and ruminal microflora. The results showed that:1) OEO had significantly increased the concentration of TP, SOD, GSH and GSH-Px in calf serum at 56 days of age(P ≤ 0.05); MON had a tendency to decrease BUN concentration in calf serum at 56 and 70 days of age(P<0.10). 2) OEO had significantly decreased the number of F. succinogenes in the rumen of calves at 56 and 70 days of age (P<0.05), and had significantly increased the number of R. albus(P ≤ 0.05); MON had significantly decreased the number of protozoa in the rumen of calves at 56 and 70 days of age (P ≤ 0.05), and had a tendency to decrease the number of R. albus (P<0.10), at 56 days of age, MON had decreased the number of R. flavefaciens in the rumen of calf(P<0.10); There was significant interaction between OEO and MON on B. fibrisolvens in the rumen of calves at 56 and 70 days of age (P ≤ 0.05), OEO and MON had a tendency of interaction on P. ruminicola at 56 days of age (P<0.10), however, there was significant interaction between OEO and MON on P. ruminicola at 70 days of age (P ≤ 0.05). 3) OEO and MON had a significant interaction on the concentration of pepsase in rumen of calves at 56 and 70 days of age (P ≤ 0.05). These results indicated that dietary supplementation with OEO could enhance immunity and antioxidant capacity of calves. MON was better than OEO in inhibiting the number of protozoa in the rumen. The effect of OEO of increasing the number of protein-degrading bacteria was better than MON. In conclusion, supplementation with OEO in diet can improve the health status of calves, modify rumen microflora activity and population. OEO can be used as a natural plant antibiotic to replace other antibiotic growth promoters for preventive treatment of calves.