Get more calves by switching to inactivated vaccines

For years, live modified virus (MLV) vaccines have been the gold standard in disease prevention in beef cow herds. Research suggests, however, that old vaccine paradigms may need to change.

A study by a team led by Dr George Perry of South Dakota State University looked at the reproductive impact of using an MLV vaccine or inactivated vaccine before breeding. In the study, 1,304 head from nine herds that had all been on an MLV vaccination program before breeding for many years received either an inactivated vaccine (Vira Shield®) 60 and 30 days before breeding, or an MLV 30. days before breeding, or a control. All females were then mated using a synchronization program.

Cows and heifers treated with the inactivated Vira Shield vaccine had a 6.5% higher artificial insemination conception rate than MLV.1 These same cows and heifers had a 4.3% higher pregnancy rate on day 56 after breeding.1 This improvement in conception and gestation rates resulted in a greater percentage of animals calving and calving within the first 30 days of the calving season.1

The importance of these numbers has a big impact on producers. First, research shows that cows that calve in the first 21 days of the calving season produce more calves over the life of the herd.2 These cows also produce more pounds of weaned calves over their lifetimes – heifers that calve early in the first year produce an additional 350 pounds of weaning weight at their sixth calf.2

Producers can earn an additional $ 2,912 (per 100 cows) profit simply by switching to an inactivated vaccine from an MLV vaccine.1 That’s $ 2,550 more for three more gravid cows based on USDA data from July 2019, and $ 362 more for calves born earlier producing 315 pounds of extra weaning weight at $ 115 / cwt. The financial benefit covers three additional pregnant cows and more calves born at the start of the calving season.

Changing your vaccination schedule is not difficult and could result in better reproductive success in your herd. To begin with, continue to administer MLV to the heifers at tagging and weaning. But instead of continuing down the MLV path, switch those heifers to an inactivated vaccine, like Vira Shield, once they enter the breeding herd. This provides an optimal balance between increasing fertility and preventing infectious abortions caused by bovine viral diarrhea (BVD)3 and infectious bovine rhinotracheitis (IBR).4

Every now and then paradigms have to change. Switching to an inactivated vaccine once the cows and heifers enter the breeding herd is a simple change that can have a significant impact on the profitability of your herd.

1Perry GA, Larimore EL, Crosswhite MR et al. Safety of vaccination with inactivated or modified live viral reproductive vaccine versus sterile saline in beef cows. J Vet Sci Res 2016; 2: 35-41.

2Cushman RA, Kill LK, Funston RN, et al. The calving date of heifers positively influences the weight of calves at weaning through six parturitions. J Anim Sci 2013; 91 (9): 4486-91.

3Zimmerman AD, et al. Efficacy of inactivated bovine herpesvirus-1 vaccine against abortion and stillbirth in pregnant heifers. JAVMA 2007; 231: 1386-1389.

4Hunt the CCL. Protection with an inactivated vaccine against IBR, BRSV and BVDV. Paper presented at the annual meeting of the American Association of Bovine Practitioners. San Antonio, Texas. 1995. Vira Shield does not have an approved application for the duration of immunity for BVD type 2.

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