State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China.
College of Animal Science and Technology, Henan University of Science and Technology, Luoyang, Henan, 471003, China.
J Dairy Sci. 2019 Mar;102(3):2298-2307. doi: 10.3168/jds.2018-15506. Epub 2019 Jan 26.
The aim of this study was to evaluate the effects of antibiotic residues in milk on growth, ruminal fermentation, and microbial community of dairy calves in their first 35 d of age. Twenty newborn Holstein bull calves were assigned to 1 of 2 treatments equally: milk replacer without antibiotics (control) and milk replacer plus 4 antibiotics: 0.024 mg/L of penicillin, 0.025 mg/L of streptomycin, 0.1 mg/L of tetracycline, and 0.33 mg/L of ceftiofur (ANT). Starter intake and fecal consistency scores of each calf were recorded on a daily basis. Body weight, withers height, body length, and heart girth were measured on d 1, 7, 14, 21, 28, and 35 before feeding in the morning. Rumen fluid was collected on d 15, 25, and 35 to determine ruminal pH, volatile fatty acids (VFA), and NH-N concentrations. A total of 10 (5 per treatment) samples of rumen fluid taken on d 35 were analyzed for microbial community. Rumen tissues from the cranial ventral sac and cranial dorsal sac were collected from 8 calves of each group for morphology analysis on d 35 after being harvested. The results showed that calves in 2 treatments had similar starter intake, body weight, withers height, body length, heart girth, and average daily gain. The ANT group showed a lower diarrhea frequency in wk 4, and no differences were found for other weeks. Calves in the ANT group exhibited a greater concentration of acetic acid in the rumen and no differences for other VFA, total VFA, rumen pH, or NH-N. As for rumen morphology, the length of papillae from cranial ventral sac of the ANT group was longer than that of the control group. The results of ruminal microbial community showed that antibiotic residues had minor effects on bacteria phyla and bacteria diversity. At the genus level, calves in the ANT group showed lower richness of Prevotella and higher richness of Acetitomaculum. In conclusion, antibiotic residues stimulated the development of ruminal papillae and increased the production of acetic acid in rumen, which might be caused by the influence of antibiotics on the ruminal microbial community.
本研究旨在评估牛奶中抗生素残留对出生后 35 天内犊牛生长、瘤胃发酵和微生物群落的影响。将 20 头新生荷斯坦公牛犊随机分为 2 组，每组 10 头：无抗生素的代乳料（对照组）和代乳料加 4 种抗生素：青霉素 0.024mg/L、链霉素 0.025mg/L、四环素 0.1mg/L 和头孢噻呋 0.33mg/L（ANT 组）。每天记录每头犊牛的开食料摄入量和粪便稠度评分。在每天早上喂料前，于第 1、7、14、21、28 和 35 天测量犊牛体重、肩高、体长和胸围。于第 15、25 和 35 天采集瘤胃液，测定瘤胃 pH 值、挥发性脂肪酸（VFA）和 NH3-N 浓度。于第 35 天采集 10 份（每组 5 份）瘤胃液进行微生物群落分析。于第 35 天从每组 8 头犊牛的瘤胃前腹囊和背囊采集瘤胃组织，用于形态学分析。结果表明，两组犊牛的开食料摄入量、体重、肩高、体长、胸围和平均日增重相似。ANT 组犊牛在第 4 周腹泻频率较低，而其他周无差异。ANT 组犊牛瘤胃中乙酸浓度较高，其他 VFA、总 VFA、瘤胃 pH 值和 NH3-N 无差异。就瘤胃形态而言，ANT 组犊牛前腹囊的乳头长度长于对照组。瘤胃微生物群落的结果表明，抗生素残留对细菌门和细菌多样性的影响较小。在属水平上，ANT 组犊牛的普雷沃氏菌属丰度较低，而醋杆菌属丰度较高。总之，抗生素残留刺激了瘤胃乳头的发育，增加了瘤胃中乙酸的产生，这可能是抗生素对瘤胃微生物群落的影响所致。
