Noninferiority field trial for evaluation of efficacy of ciprofloxacin associated with internal teat sealant as dry-off protocol
The aim of this study was to compare the efficacy of two dry-off protocols: (a) dry cow therapy using ciprofloxacin hydrochloride 400 mg followed by the administration of an internal teat sealant composed of 4 g of bismuth subnitrate, and (b) a positive control using dry cow therapy with 250 mg cephalonium followed by the administration of 2.6 g bismuth subnitrate internal teat sealant. A total of 578 Holstein cows selected from 7 commercial herds were randomly allocated into two groups at drying off: (a) ciprofloxacin hydrochloride 400 mg (CH) associated with ITS, n = 1112 mammary quarters/296 cows, or (b) positive control (PC) = cephalonium (250 mg) associated with ITS, n = 1058 mammary quarters/282 cows). A total of 1787 out of 2170 mammary quarters (82%) had negative culture at drying off. The microorganisms most frequently isolated at drying off were CNS (5.62%), Strep. uberis (1.9%), Corynebacterium spp. (1.8%), and Staphylococcus aureus (1.01%). A total of 465 mammary quarters experienced new intramammary infections (NIMIs), and the main microorganisms causing NIMI were CNS (21.94%), Strep. uberis (17.2%), and Pseudomonas spp. (9.7%). The CH protocol was not inferior to PC, as the cure risk of mammary quarters CH-treated was at the noninferiority limit. However, the mammary quarters treated by CH protocol had 24% and 31% lower risk of overall NIMI and NIMI caused by major pathogens, respectively, than mammary quarters dried with the PC protocol. In addition, the mammary quarters treated with CH protocol had a lower risk of CM through the first 60 DIM than those treated with PC protocol. Both DCT protocols showed similar odds of microbiological cure, but the CH protocol had greater prevention against NIMI during dry-off period.
KeywordsCephalonium Dry-cow therapy Mastitis New IMI Noninferiority
Christie, Atkins, Munch-Petersen test
Dry cow therapy
Days in milk
Internal teat sealant
New intramammary infections
Somatic cell count
We acknowledge the dairy farms that participated in this study. We also thank the Quality Milk Research Laboratory (Qualileite) team, at University of São Paulo, for helping data and sample collection. The authors acknowledge Ourofino Animal Health (Cravinhos, SP, Brazil) for providing funding for the study.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Statement of animal rights
The present study was approved (protocol number CEUA 8542090218) by the Ethic Committee on Animal Use of the School of Veterinary Medicine and Animal Science (CEUA/FMVZ/USP), in accordance with the rules issued by the National Council for Control of Animal Experimentation (CONCEA) as well as Law 11.794 of October 8, 20008, Decree 6899 of July 15, 2009.
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