The effects of preventive measures against neonatal diarrhea and bovine respiratory disease (BRD) on the reproductive and milk production performance of calves in later stages

Abstract This study aims to investigate the performance parameters of 81 calves raised on a dairy farm, to evaluate the impact of neonatal calf diarrhea and bovine respiratory disease (BRD) on these parameters, and to assess the effectiveness of a preventive nutritional strategy in mitigating the effects of these diseases. Holstein-Friesian crossbreed (HF × Montbéliarde) calves were divided into control (C, n=70) and experimental (E, n=11) groups. In the first phase of the study, the experimental group received a commercial feed additive for 10 days post-birth, while the control group received no additive. All calves were vaccinated against BRD at scheduled intervals. In the second phase, performance parameters were evaluated, including age at insemination resulting in pregnancy (AIRP), pre-pregnancy body weight (PPBW), number of inseminations per pregnancy (NIPP), initial calving body weight (ICBW), age at first calving (AFC), and daily milk yield (MY). The study was conducted over a period of 33 months. In the first part of the study, 36 out of 81 animals (44%) experienced illness. Among the affected animals, 28 had diarrhea (including those with both conditions), 23 had respiratory diseases (including those with both conditions), 13 had only diarrhea, 8 had only respiratory diseases, and 15 suffered from both diarrhea and respiratory diseases. Although BRD pathogens were not investigated, rotavirus was identified as the primary cause of diarrhea. Data from the second part of the study revealed statistically significant differences in ICBW, NIPP, and MY between sick (n=36) and healthy (n=45) animals (p