含β-内酰胺类药物有抗奶对犊牛生长发育和血液免疫指标的影响

摘要

试验旨在研究饲喂含β-内酰胺类药物有抗奶对荷斯坦公犊牛生长发育和血液免疫指标的影响.选用3日龄、体重(42.64 kg±1.16 kg)相近的公犊牛18头,随机分为2组.对照组饲喂正常牛奶,试验组饲喂有抗奶,犊牛60日龄断奶,试验期为180 d.试验第10、20、30、40和50天分别采集正常牛奶和有抗奶,测定乳成分、大肠杆菌数和乳中抗生素含量.试验第30、60、90和180天逐头空腹称重,测量体尺,并计算平均日增重(ADG).试验第7、15、30、60、90和180天于晨饲前对公犊牛空腹静脉采血,制备血清,测定血清免疫指标.结果显示:①试验牛场有抗奶中β-内酰胺类抗生素含量为268.65 μg/L,且有抗奶的乳蛋白含量、体细胞数(SCC)和大肠杆菌数显著高于正常牛奶(P<0.05);②饲喂有抗奶显著降低公犊牛第30天时的体重和试验60 d内的ADG(P<0.05),显著降低公犊牛第90天时的体长及第60和90天时的胸围(P<0.05);③与对照组相比,试验组公犊牛IgA在第30、60和90天时显著升高(P<0.05),IgM在第7天时显著升高(P<0.05),IgG在第30和60 天时显著升高(P<0.05);IL-2和TNF-α在第15和30 天时均显著升高(P<0.05).结果提示,饲喂有抗奶明显降低犊牛哺乳前期日增重,且在一定程度上提高犊牛断奶前后的血清免疫指标水平.%This experiment was conducted to investigate the effect of feeding antibiotic-contaminated milk on growth performance and blood immune parameters of Holstein calves.Eighteen calves (3 days old) with similar body weight were selected and randomly assigned into two feeding groups, which were fed bulk milk (control group) or antibiotic-contaminated milk (experimental group) until 60 days old.The experiment period lasted for 180 d.Bulk milk and antibiotic-contaminated milk were respectively collected on 10, 20, 30, 40, 50 d, which were used to detect milk composition content, E.coli and antibiotics in milk.Body weight and body measurement were severally measured on 30, 60, 90 and 180 d, and then average daily gain (ADG) was calculated.On 7, 15, 30, 60, 90 and 180 d, serum samples were collected from Holstein calves, and used for measure of immunoserologic indexes.The results showed that β-lactam antibiotic residues were 268.65 μg/L in antibiotic-contaminated milk, and the milk protein content, somatic cell counts (SCC), and E.coli number in antibiotic-contaminated milk were all significantly higher than that in bulk milk (P<0.05).Feeding antibiotic-contaminated milk significantly decreased body weight on 30 d and ADG in 60 d, as well as body length on 90 d and heart girth on 60 and 90 d (P<0.05).Compared with control group, the calves''IgA levels on 30, 60, and 90 d, IgM levels on 7 d, IgG levels on 30 and 60 d of experimental group were all significantly increased (P<0.05).Likewise, IL-2 and TNF-α levels on 15 and 30 d of experimental group were also significantly increased (P<0.05).It was concluded that feeding antibiotic-contaminated milk could obviously decrease calves''ADG of early lactation, and to some extent enhance the levels of serum immune parameters before or after weaning.