Routine postpartum treatment of dairy cattle with intrauterine neomycin sulfate boluses

Within location, 119 dairy cattle from two experiment station herds, which had no problems associated with parturition, were randomly either treated by insertion of two intrauterine boluses containing a total of 1000 mg neomycin sulfate 24 h postpartum or maintained as a control. Uteri and ovaries of all cows were palpated 17 to 24 days postpartum and at 14 day intervals thereafter until inovulation of the uterus was judged complete and an estrus had been observed. All cows were inseminated at the first estrus after 60 days postpartum and at each estrus thereafter until conception. Cows treated with neomycin sulfate required more services per conception (1.7 to 1.4) and were open more days before conception (100.5 to 88.5) than the controls. The probable cause of the lowered reproductive efficiency is discussed. Treatment did not later significantly days to ovulation, estrus, involution, or first service. Three treated and five control animals needed additional uterine treatment. Routine intrauterine treatment of all cows with neomycin sulfate boluses should not be recommended.