Document Type : Research Paper
Authors
1
Ph.D. Candidate, Department of Animal Science, Faculty of Agriculture, Univeristy of Zanjan, Zanjan, Iran
2
Professor, Department of Animal Science, Faculty of Agriculture, Univeristy of Zanjan, Zanjan, Iran
3
Professor, University College of Agriculture & Natrual Resources, University of Tehran, Karaj, Iran
4
University Distinguished Professor of Microbiology, Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS, United States
Abstract
To investigate the effects of tylosin injection in dairy cows at dry period on performance, milk composition and some blood parameters in subsequent lactation, 120 Holstein cows with a mean weight of 720±20Kg were used. Treatments were no tylosin (treatment 1; control group), injected 0.025 (treatment 2 low tylosin; LT) and 0.05 (treatment 3 high tylosin; HT) ml tylosin 20% per kg of body weight per day for 3 days after drying days. To determine biochemical parameters blood samples were collected at the drying day and 0, 7, 14, and 21 of lactation. Data of milk production and composition were collected for 4 months after calving. The difference between serum total protein concentration between treatments tended to be significant (P=0.051). Aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities were lower in the control group (P<0.05). The activity of creatine kinase (CK) tended to be significant (P=0.053) with tylosin injection. Milk production, milk protein and fat contents, calving parameters and periparturition disorders did not affect by tylosin injection (P>0.05). The incidence of mastitis in the groups receiving tylosin was significantly lower than the control group (P <0.05). Results suggest that tylosin do not cause dramatic changes in serum clinical chemistry profiles, but it was effective in reducing the occurrence of mastitis and had no negative effect on parturition, disorders around it and calf losses until 2 month of age.
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