# Dairy Cattle Infection with Bovine Rotavirus at Different Growth Stages and Its Impact on Health and Productivity

## TL;DR

This study examines bovine rotavirus infection in dairy cattle, showing it significantly impacts calf health and productivity, especially in milk-fed calves.

## Contribution

The study identifies BRV prevalence in dairy farms in Hebei, China, and quantifies its impact on calf health and productivity metrics.

## Key findings

- Milk-fed calves had the highest BRV infection rate at 14.58%.
- BRV positivity was positively linked to calf morbidity and mortality but negatively linked to weight gain.
- Older farms and autumn season showed higher BRV positivity rates.

## Abstract

As an important infectious disease, bovine rotavirus (BRV) poses a serious threat to cows, especially milk-fed calves. BRV can cause severe diarrhea, dehydration, and even death in calves. Hebei, a large dairy farming province in China, has a considerable number of dairy cows, but the population positive rate of BRV in farms of different ages during large-scale farming in this region is not known, and its effect on the production indicators of morbidity, mortality, average daily weight gain (ADG), and average daily weight gain pass rate (ADGPR) of milk-fed calves is not clear. The results showed that milk-fed calves were the most susceptible group to BRV infection, and the positive rate was positively correlated with morbidity and mortality and negatively correlated with ADG and ADGPR. Therefore, strengthening the control of BRV is very important to reduce the loss of large-scale farming.

This study evaluated the prevalence of BRV infection and its impact on the health of dairy cows at different growth stages, with a particular focus on milk-fed calves. BRV was detected in rectal swabs via RT–qPCR. In the total sample of 2400 dairy cows examined at three farms, 103 (4.29%) were found to be positive for BRV. Similarly, of the 480 milk-fed calves, 70 (14.58%) were also found to be positive for BRV. Negative binomial regression analysis revealed that older farms had higher average BRV positivity rates than new farms did and that the BRV positivity rate was higher in autumn than in the other three seasons. Additionally, BRV positivity rates gradually decreased as calf age increased. In milk-fed calves, BRV positivity was positively correlated with morbidity and mortality and negatively correlated with ADG and ADGPR. These findings provide valuable insights for farm management, particularly for older farms, highlighting the detrimental effects of BRV infection on milk-fed calves and underscoring the importance of targeted control strategies to reduce BRV prevalence and optimize dairy production efficiency.