Noninferiority trial on the efficacy of premilking teat disinfectant against naturally occurring new intramammary infections using a novel 2-step diagnostic process

Abstract

The objective of the study was to evaluate premilking teat disinfectant efficacy with the use of a novel diagnostic protocol against a positive control. The evaluation of efficacy was based on establishing noninferiority of a new premilking teat disinfectant compared with an existing premilking teat disinfectant. Approximately 200 cows were randomly allocated to 1 of 2 groups. Study personnel were blinded as to cow allocation and identification of the premilking disinfectants. Quarters were disinfected using a dip cup before milking with either the control or experimental product. The disinfectant was left on the teat for approximately 30s before being wiped off in preparation for milking. Quarter-level bacteriological infection status was established at the beginning of the study and quarter milk samples were collected biweekly thereafter. Bacteriological analyses were performed only when somatic cell counts in milk samples crossed a parity-specific threshold. Poisson regression models were used to analyze data. The difference in the rate of new intramammary infections was small and the upper bound of the 95% confidence interval of the rate difference was smaller than a predefined noninferiority limit. Based on the observed difference in new intramammary infections rate between the experimental and control product, it was concluded that the experimental disinfectant was not inferior compared with the positive control. The protocol used in this study proposes a valid and economically attractive methodology to evaluate the efficacy of teat disinfectants relative to a positive control.

A review of test protocols for the evaluation of teat disinfectants

“…(), Ceballos‐Marquez et al . () and Godden et al . () showed that the bacteriological status of their herds was determined by collecting milk samples before the commencement of the study.…”

“…() collecting a monthly sample, whereas Ceballos‐Marquez et al . () collected milk samples biweekly but only cultured them depending on SCC analysis.…”

“…() and Ceballos‐Marquez et al . () considered an IMI as a new infection based on the presence of a microorganism that was not identified in that quarter previously. Ceballos‐Marquez et al .…”

Iodide Residues in Milk Vary between Iodine‐Based Teat Disinfectants

“…Iodine is crucial to human health both as an essential dietary element necessary for proper thyroid function (WHO ) and as a germicide important in the reduction of bacterial populations, particularly as pre‐ or post‐milking teat disinfectant (Galton ; Ceballos‐Marquez and others ). Although iodine deficiency poses health risks and remains problematic in many parts of the world, over‐dosage of iodine is also associated with health risks, such as toxic goiter, hyper‐thyroidism, and hypo‐thyroidism (Delange and others ; WHO ; Medici and others ; Sun and others ; Shi and others ).…”

Short communication: Efficacy of glycolic acid-based and iodine-based postmilking barrier teat disinfectants for prevention of new intramammary infections in dairy cattle

“…Adjustments to existing protocols have been proposed to test the noninferiority of an experimental product compared with a control product, based on adequate statistical approaches and reasonable logistical modifications (Ceballos-Marquez et al, 2013).…”