日粮中添加恩拉霉素和脂多糖攻毒对断奶仔猪生产性能和血清生化指标的影响

摘要

In this experiment, the effects of normal and over dosage of enramycin (ER) on the performance and blood biochemical indexes of weaned piglets were investigated during the periods with or without lipopolysaccharides (LPS) challenge after withdrawal of ER to explore the efficiency and safety of ER. A total of 36[ Duroc x (Landrace x Yorksire), DLY] piglets weaned at 21d were randomly assigned to three treatments with twelve replicates to receive basal diet or basal diet added with ER at 5, 80 mg/kg (ER-supplemented period), respectively. After 21 d feeding, all piglets received basal diet ( withdrawal period). After one week, six piglets from each treatment were randomly received intraperitoneal injection of LPS at a dosage of 200 |xg/kg body weight, the rest received equivalent saline as a control. Before and 2.5 h, 3 d after stress, piglets were weighted and fasting blood samples were collected to prepare the serum. Results showed that 5 mg/kg and 80 mg/kg ER dietary treatments resulted in the improvements of average daily gain and feed intake in various degrees during different stages (d 0-7, d 8~14, d 15~21, and d 0~21), but had no effects on feed conversion. During withdrawal time (d 22~28), the performance of weaned piglets fed ER diets was slightly better than the piglets fed the control diet. After stress, average daily gain and average daily feed intake of the piglets challenged with LPS decreased significantly (P<0.05). A significant increase of average daily feed intake was observed in LPS-challenged pigs fed the ER diet (P<0.05). Before LPS-challenged period, physiological and chemical indexes in the serum were not significantly affected by ER (ft>0.05). Two and a half hours after LPS injection, MDA, cortisol and insulin-like growth factor 1 levels in serum increased significantIy(P<0.05). Three days after LPS injection, serum insulin-like growth factor 1 concentration was significantly increased (P<0.01), serum nitric oxide concentration was significantly decreased (P<0.01), and there was a tendency toward elevated serum cortisol concentration (P<0.1), while ER significantly reduced the serum insulin-like growth factor 1 concentrations (P<0.01). In addition, a significant interaction effect of ER and LPS on serum insulin-like growth factor 1 regulation (P<0.05) was observed.%本试验旨在研究在正常与免疫应激条件下添加恩拉霉素对仔猪的作用效果及安全性.将36头21日龄断奶、健康、DLY阉公仔猪随机分为3个处理,每个处理12个重复；分别饲喂基础日粮及在基础日粮中添加5、80 mg/kg恩拉霉素日粮(加药期),21 d后,各组均饲喂基础日粮(停药期),7d后,每处理随机取出6头仔猪腹腔注射LPS 200μg/kg体重(应激期),剩余6头仔猪腹腔注射等量生理盐水.分别于应激前和应激后2.5 h、3d采血.结果表明:日粮添加5mg/kg和80mg/kg恩拉霉素不同程度提高0～7、8～14、15～21 d和0～21 d仔猪的日增重和采食量,而对饲料增重比无影响；前期添加恩拉霉素组仔猪的生产性能在停药期仍略优于对照组；LPS应激导致仔猪平均日增重和平均日采食量显著下降(P＜0.05)；加药期添加恩拉霉素可显著提高应激期仔猪平均日采食量(P＜0.05).注射LPS前,各组血清理化指标没有显著差异(P＞0.05)；注射LPS 2.5 h后,血清丙二醛、皮质醇和IGF-1的含量显著提高(P＜0.05)；注射LPS 3d后,血清IGF-1浓度显著提高(P＜0.01),NO浓度显著降低(P＜0.01),皮质醇浓度有提高的趋势(P＜0.1)；日粮添加恩拉霉素显著降低了血清中IGF-1的浓度(P＜0.01),与LPS具有显著互作效应(P＜0.05).