| Oregano essential oil is a feed additive extracted from oregano plant which could exhibit antimicrobial properties that makes them potential antibiotic alternatives.Colon health is critically important for the growth and health of new born calves and its been reported that the colon health and growth and development of newborn calves could be improved by both oregano essential oil and rumensin.The objective of this study was to evaluate the effects of adding oregano essential oil and rumensin,individually or in combination,on the production performance and health condition of newborn calves.80 newborn Holstein calves were selected and allocated randomly into 4 groups with each group containing 20 heads of calves.4 Treatments were as followed: mixed group with 20% rumensin and oregano essential oil added into the concentrate with dosages of 3.6kg per ton and 4kg per ton,respectively,rumensin group with only 20% rumensin added into concentrate with a dosage of 3.6kg per ton;oregano essential oil group with only oregano essential oil added into concentrate with a dosage of 4kg per ton,and control group with no adding of rumensin or oregano essential oil.The 4 groups of calves were fed from day 0(birth)to day 70 of age and growth performance,blood biochemical indexes,diarrhea incidence,nutrient digestibilities,contents of serum volatile fatty acids were measured fortnightly and the results were as followed.1.Compared with other groups,dry matter intake was higher when fed with oregano essential oil(P < 0.01),dry matter intake of the calves fed with rumensin had no significant difference compared with that of control group(P > 0.05),adding oregano essential oil showed good restrain action on diarrhea(P < 0.01).2.Compared with control group,the average daily gain was significantly higher when oregano essential oil was fed(P < 0.01),body weight numbers on day 70 of age in mixed group,rumensin group and oregano essential oil group were 6.7kg,1.0kg and 5.6kg higher than the corresponding number of control group,respectively,which indicated that oregano essential oil showed ideal growth promoting effect and good synergy with rumensin.3.The body size indexes of calves when fed with oregano essential oil increased significantly(P < 0.01).But the increase of body size indexes of calves fed with rumensin was not significant(P > 0.05),except abdominal circumference which is significant(P < 0.01).4.Adding oregano essential oil could significantly increase the concentrations of total serum protein,immunoglobulin G,immunoglobulin M and immunoglobulin A(P < 0.01),no significant effect was detected on the concentrations of total serum protein,immunoglobulin G,immunoglobulin,M and immunoglobulin A when added with rumensin(P > 0.05),the interaction effect between oregano essential oil and rumensin was not significant(P > 0.05).5.Digestibilities of crude protein,dry matter,acid detergent fiber,neutral detergent fiber,starch,phosphate,calcium and chloride were higher compared with the number from control group when fed with oregano essential oil(P < 0.01).Compared with control,adding rumensin could increase the digestibilities of crude protein,dry matter,acid detergent fiber,neutral detergent fiber,phosphate,calcium(P < 0.05 or P < 0.01)but the effect on the digestibilities of starch and chloride were not significant(P > 0.05).The interaction effect of the two was significant to digestibilities of crude protein,dry matter,acid detergent fiber,neutral detergent fiber,phosphorus and calcium(P < 0.05 or P < 0.01).6.Compared with control group,when added with oregano essential oil,the concentrations of acetic acid,propionic acid,isobutyric acid,butyric acid,isovaleric acid and total volatile fatty acid in the blood were increased significantly(P < 0.01),propionic acid concentration was significantly higher than the that of control group when added with rumensin(P < 0.05),but different treatment showed no significant effect on the concentration of pinalic acid(P > 0.05). |
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