Abstract：
The aim of this study was to perform a positive-controlled field study under natural exposure conditions to test the efficacy of a newly developed chlorine dioxide-based postmilking teat disinfectant (experimental product, EX) for noninferiority compared with an already established chlorine dioxide-based teat disinfectant (positive control product, PC). After blocking by parity, approximately 200 Holstein cows in early to mid-lactation stages from a dairy farm near Padua, Italy, were randomly assigned to one of 2 groups. Over a 13-wk period between September and December 2021, the teats of cows were dipped with the EX or the PC after each milking. Milk samples were collected from individual quarters of enrolled cows for 13 wk to determine infection status. Teat condition was assessed at wk 1, 5, and 9. Mixed logistic regression was used to analyze the effect of treatment on the incidence of new intramammary infections. For the noninferiority analysis, the upper limit of the 95% confidence interval for the difference in new intramammary infection (NIMI) rate between the 2 treatments (EX - PC) had to be to the left of the critical value d (0.035) to conclude that EX was noninferior to PC in terms of the risk of NIMI. The results showed that the incidence of new infections in the quarters treated with EX (3.1%) was not different from that in the udder quarters treated with PC (2.6%). No overall difference was found between the treatments in terms of teat condition. As the upper limit of the 95% confidence interval of the NIMI rate difference was smaller than the predefined noninferiority limit, we concluded that the EX was noninferior compared with the PC.
摘要：
本研究的目的是在自然暴露条件下进行阳性对照的现场研究，以测试新开发的基于二氧化氯的挤奶后乳头消毒剂的功效（实验产品，EX）与已经建立的二氧化氯制乳头消毒剂（阳性对照产品，PC）。在被奇偶校验阻塞后，从帕多瓦附近的一个奶牛场，大约200头处于泌乳早期到中期的荷斯坦奶牛，意大利,随机分为两组。在2021年9月至12月的13周期间，每次挤奶后用EX或PC浸渍奶牛的乳头。从注册母牛的各个季度收集牛奶样品，持续13周，以确定感染状况。在第1、5和9周评估乳头状况。采用混合logistic回归分析治疗对新发乳腺感染发生率的影响。对于非劣效性分析，两种治疗方法(EX-PC)间新的乳房内感染(NIMI)率差异的95%置信区间的上限必须位于临界值d(0.035)的左侧,才能得出EX在NIMI风险方面不劣于PC的结论.结果表明，用EX治疗的病房（3.1％）的新感染发生率与用PC治疗的乳房病房（2.6％）的新感染发生率没有差异。在乳头状况方面,在处理之间没有发现总体差异。由于NIMI比率差异的95%置信区间的上限小于预定义的非劣效性极限,我们得出的结论是，与PC相比，EX并不逊色。
