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Effect of treatment at dry-off with intramammary antibiotics, internal teat sealants, or both on the health of dairy cows.

W. R. ElAshmawy




Effect of treatment at dry-off with intramammary antibiotics, internal teat sealants, or both on the health of dairy cows.
W. R. ElAshmawy*1,2, E. Okello1,3, D. R. Williams1, R. J. Anderson4, P. Rossitto1, J. D. Champagne1, K. Tonooka1, K. Glenn1, B. Karle5, T. W. Lehenbauer1,3, S. S. Aly1,3. 1Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California-Davis Tulare, CA, 2Department of Internal Medicine and Infectious Diseases, Faculty of Veterinary Medicine, Cairo University Giza, Egypt, 3Department of Population Health & Reproduction, School of Veterinary Medicine, University of California-Davis Davis, CA, 4Animal Health Branch, California Department of Food Agriculture Sacramento, CA, 5Cooperative Extension, Division of Agriculture and Natural Resources, University of California Orland, CA.

Prevention and control of mastitis continues to be one of the major challenges facing the dairy industry. Intramammary antibiotic (AB) infusion at dry-off is used to treat subclinical mastitis at dry-off and prevent clinical mastitis during the dry period. In addition, internal teat sealants (ITS) are used to prevent exposure to new infections during the dry period. A block randomized trial was completed between December 2016 and August 2018 on 8 California dairy herds. A total of 1,273 cows were block randomized to 1 of 4 treatments (None, AB, ITS, or both) over 2 seasons, summer and winter. Composite milk samples were collected at enrollment (dry-off) and within 14 d after calving for bacteriological culture. The objectives of this clinical trial were to compare the health outcomes between the treatment groups, specifically: 1) clinical mastitis and culling during the dry period and the first 150 d in milk (DIM) in the subsequent lactation, and 2) bacteriological cure and new infections in the first 150 DIM in the subsequent lactation. Logistic regression models showed no significant differences in the odds of clinical mastitis or culling between cows treated at dry-off with AB, ITS, or both compared with the controls (None). Cows treated with both AB and ITS had the highest odds of bacteriological cure (OR 3.05; P < 0.01), followed by cows treated with AB (OR 2.38, P < 0.01), followed by ITS (OR 2.0; P < 0.01) in comparison to controls. Cows treated with AB and ITS at dry off had the lowest odds (OR = 0.45; P < 0.01) of developing new infections after calving followed by cows that received internal teat sealants (OR = 0.51; P < 0.01); however, cows that received only AB had numerically lower odds (OR = 0.70; P = 0.09) in comparison to untreated cows. The most common bacteria isolated by culture at dry off, post-calving and at the first mastitis were Coagulase negative staphylococci, Streptococcus spp., Corynebacterium spp., Aerococcus spp., Coliforms and Lactococcus spp. Dry cow treatment with AB and/or ITS increased the bacteriological cure and reduce the new infections.

Keywords: dry cow therapy, mastitis, clinical trial.

Biography: Wagdy ElAshmawy is specialized in veterinary epidemiology and infectious diseases. ElAshmawy graduated from Cairo University with a Bachelor of Veterinary Sciences (BVSc) in 2004. Between 2005 and 2016 he joined the faculty as a graduate student, instructor and with completion of his graduate degrees (MVSc and PhD) ascended to the rank of assistant professor of Infectious Diseases at the Department of Internal Medicine and Infectious Diseases, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt. ElAshmawy in 2019 finished the Dairy Production Medicine residency from UC Davis at the Veterinary Medicine Teaching and Research Center in the heart of the dairy's industry, Tulare, CA. ElAshmawy's strong interests in epidemiology and infectious diseases were enriched with his Master in Preventive Veterinary Medicine degree (MPVM) in epidemiology with special interest on the diagnosis and prevention of diseases in 2018. In addition, ElAshmawy pursuing his research interests at Dairy Epi Lab at VMTRC, UC Davis working with a large trial on building the algorithm for the selective dry cow therapy on dairy herds. In addition, he is researching the risk factors associated with different health and production parameters of dairy cows in different treatment scenarios. He is working on mathematical modelling of the effect of cow bunching and stable flies on the milk production and estimating the economic losses to provide a guideline for the dairy industry on their budget to spend on control of stable flies.