Sessions

BRDC (bovine respiratory disease complex) causes significant economic losses and responsible for a significant number of antibiotic treatments used on dairy farms. Colostrum intake is crucial for newborn calves as it is a key factor in determining their immunity during the first months of life. Clinical BRDC most often manifests itself as a result of weaning stress and its diagnosis in the early stages is quite difficult under farm conditions; currently the most effective method is lung ultrasound (TUS).

The aim of our research was to find a correlation between colostrum quality and the efficiency of passive transfer in calves and then to consider the combined role of these factors in the development of BRDC before and after weaning.

We involved 30 heifers in our study from a hungarian dairy farm, they were monitored until 6 months of age. We performed bacteriological tests on the colostrum, measured the BRIX % and weighed the animals at birth and detailed clinical examinations on each calf nine times, evaluated them using Wisconsin scoring, and performed regular TUS examinations with a linear rectal probe from four weeks of age.

Based on our results, we concluded that contaminated colostrum with a high total germ count had the greatest influence on the success of passive transfer at the studied farm. All of these animals (n=5) suffered from clinical BRDC until and after weaning. There was a statistically significant difference in the TUS score before weaning between calves fed colostrum containing the pathogen (n=15) and calves fed olostrum with a high total germ count (n=5) and colostrum without the pathogen (n=5) had a statistically significant difference in TUS scores before selection (p=0.041), but this could not be confirmed after selection.

The animals were divided into two groups: those with a TUS score higher than 3 at the time of selection (n=12) and those without (n=17). The daily weight gain of the control group until selection was 0.72 kg/day on average, while the daily weight gain of the group showing severe lesions was 0.62 kg/day on average. The difference between the two groups was significant (p=0.039). However, there was no difference in TUS scores between the two groups after weaning, The average total score of the control group in the 3 TUS tests was 8.2, while for those showing severe lesions, this number was 10.1.

Our research has proven that feeding poor-quality colostrum has a significant effect on the development of BRDC before weaning, but we were unable to confirm its effect after weaning. This is probably due to poor ventilation conditions during post-weaning group housing on the farm and the small number of animals receiving pathogen free colostrum.

Overall, it can be said that colostrum feeding hygiene needs to be improved at the farm, as the high total bacterial count and the presence of pathogens in colostrum have a significant impact on the health and weight gain of the animals.