BVD Impact on Morbidity, Mortality and Performance of Feedlot Cattle
The negative impact that BVDv-PI animals can have on their pen-mates
The January edition of the Journal of American Veterinary Medical Association included the article, “Effect of constant exposure to cattle persistently infected with bovine viral diarrhea virus on morbidity and mortality rates and performance of feedlot cattle,” JAVMA, Vol. 244, No. 2, January 15, 2014.
The summary of three companion trials provides additional insight into the negative impact that BVDv-PI animals can have on their pen-mates.
Trial 1 evaluated the effect of constant PI exposure or PI non-exposure to BVD naive calves in the feed lot. Naïve calves were either vaccinated with a multivalent modified live respiratory vaccine within 24 hours of arrival or not vaccinated at arrival. Recorded values represent the percentage of the calves that were diagnosed with bovine respiratory disease and treated at least once.
1a Vaccinated on arrival / No BVDv-PI exposure 19.57% (no PI in feedlot pen)
1b Not Vaccinated / No BVDv-PI exposure 30.43% (no PI in feedlot pen)
1c Vaccinated on arrival / BVDv-PI exposure 39.13% (PI in feedlot pen)
1d Not Vaccinated / BVDv-PI exposure 63.04% (PI in feedlot pen)
Since almost all calves are vaccinated on arrival at the feedlot the two treatments of practical interest are 1a and 1c.
Trials 2 and 3 compared the effects of pre-weaning vaccination or pre-weaning exposure to BVDv-PI in calves that were subsequently exposed to BVDv-PI cattle throughout the feeding period.
2a Vaccinated w/ BVDv-PI exposure pre-weaning 43.24% (PI in feedlot pen)
2b Not Vaccinated w/ BVDv-PI exposure pre-weaning 42.31% (PI in feedlot pen)
2c Vaccinated w/ no BVDv-PI exposure pre-weaning 56.76% (PI in feedlot pen)
2d Not Vaccinated w/ no BVDv-PI exposure pre-weaning 63.16% (PI in feedlot pen)
3a Vaccinated pre-weaning 32.83% (PI in feedlot pen)
3b Not Vaccinated pre-weaning 42.25% (PI in feedlot pen)
Conclusions:
- Both Vaccination and natural exposure to BVDV can reduce the negative impact of constant exposure to a BVD-PI animal in the feedlot.
- Constant exposure to a BVD-PI animal in the feedlot can increase BRD Morbidity by a factor of 2 in vaccinated animal and a factor of 3 in non-vaccinate or non-exposed animals.