BACKGROUND: Bovine respiratory disease (BRD) continues to be great challenge in calf rearing units. The urgent need to decrease the use of antibiotics and increase animal welfare in beef production has forced us to introduce new preventive methods. Vaccinations could contribute to the solution, but the high incidence of BRD already at an early age has made it difficult to introduce suitable vaccination programs. Challenge studies have shown promising results in 3-14 day old calves vaccinated with intranasal BRD vaccine, but very few field trials are available to assess the efficacy of the intranasal vaccines in field conditions. We evaluated the effect of one dose of commercial intranasal vaccination on calf mortality, daily gain, and treatment incidence for BRD in one calf rearing unit. In total, 497 calves (mean age 19 days) were included in our study, 247 of which were vaccinated at the time of arrival to the unit and 250 served as negative controls (unvaccinated). Vaccinated and unvaccinated calves were situated in separate compartments until weaning. Daily gain, treatment incidence, and mortality were recorded until the calves were transported to the finishing unit, which averaged 154.5 days from arrival.
RESULTS: Average daily gain over the complete study period was 1151.9 g/day (SD 137.9) for the vaccinated calves and 1139.5 g/day (SD 135.9) for the unvaccinated calves. Intranasal vaccination combined with older arrival age (17 days or older) resulted in a higher daily gain (47.8 g/day) compared with unvaccinated calves (coef. 0.0478, p = 0.003). This association was not recorded in calves that were younger than 17 days upon arrival. Intranasal vaccination was not significantly associated either with mortality (OR 0.976, p = 0.968) or treatment incidence for BRD (OR 1.341, p = 0.120). In total, six vaccinated calves (2.43%) and six unvaccinated calves (2.40%) died during the study period.
CONCLUSIONS: Vaccinating arriving calves with intranasal vaccine in the calf rearing unit did not decrease the mortality or treatment incidence for BRD, but it significantly improved the weight gain in calves transported to the unit at the age of 17 days or older.

Our objective was to determine the effect of vaccination and deworming at arrival (d 0) on bovine respiratory disease (BRD) incidence, mortality, and growth of stocker calves. Calves (n=80) were stratified by d -3 weight and fecal egg count (FEC) into 20 pens of 4 calves. Pens were randomly assigned to treatments in a 2×2 factorial design, testing d 0 vaccination (modified-live respiratory virus and clostridial vaccine, or not) and deworming (oral fenbendazole and levamisole, or not). Body weights were measured on days 0, 14, 28, 42, 56, 70, and 85, and FEC were measured on days -3, 28, 56, and 85. Incidence of BRD was greater for d 0 vaccination (RR=3.2), high fever (≥104°F, ≥40°C) at d 0 (RR=6), and higher d -3 FEC (RR=1.2 per 100 epg). Mortality was greater for d 0 vaccination (OR=8.3) and high fever (OR=41.6). Growth was 10.3 lb (4.7 kg) lower for d 0 vaccination, 24 lb (11 kg) and 16 lb (7.3 kg) lower for moderate (103°F to 103.9°F; 39.4°C to 39.9°C) and high fever, respectively, and 17.6 lb (8 kg) lower for each additional BRD treatment a calf received. Deworming was neither beneficial nor detrimental to any health or performance factors. Health and growth performance of stocker calves may be adversely affected by vaccination at arrival, higher arrival FEC, and fever at arrival.
Notre objectif était de déterminer l’effet de la vaccination et de la vermifugation à l’arrivée (j0) sur l’incidence du complexe respiratoire bovin (CRB), la mortalité et la croissance des veaux d’élevage. Les veaux (n=80) ont été stratifiés selon le poids et le compte d’œufs fécaux (COF) à j-3 et placés dans 20 enclos avec chacun quatre veaux. Les enclos étaient assignés aléatoirement aux traitements selon un plan factoriel 2×2 avec la vaccination à j0 (avec ou sans vaccin anti-clostridial avec virus respiratoires vivants modifiés) et la vermifugation (avec ou sans injection orale de fenbendazole et de lévamisole) comme facteurs. Le poids corporel a été mesuré aux jours 0, 14, 28, 42, 56, 70 et 85 et le COF a été fait aux jours −3, 28, 56 et 85. L’incidence du CRB était plus élevée suivant la vaccination à j0 (RR=3.2), lorsque la fièvre était élevée à j0 (≥104°F, ≥40°C) (RR=6) et lorsque le COF était plus élevé à j-3 (RR=1.2 par 100 oeufs par gramme). La mortalité était plus élevée suivant la vaccination à j0 (RC=8.3) et lorsque la fièvre était élevée (RC=41.6). Il y a eu une perte de croissance de 10.3 lb (4.6 kg) suivant la vaccination à j0, une perte de 24.1 lb (11 kg) lorsque la fièvre était modérée (103–103.9°F), une perte de 16 lb (7.3 kg) lorsque la fièvre était élevée et une perte de 17.5 lb (8 kg) pour chaque traitement additionnel contre le CRB reçu par un veau. La vermifugation n’a pas eu d’effet bénéfique ou néfaste sur tous les facteurs reliés à la santé ou à la performance. La santé et la croissance des veaux d’élevage peuvent être affectées négativement par la vaccination à l’arrivée, par un COF initialement élevé et par la fièvre à l’arrivée.

Nitric oxide, a molecule produced in most mammalian cells, has bactericidal and virucidal properties. Nasal instillation of a nitric oxide releasing solution (NORS) on arrival at the feedlot was recently reported as non-inferior to a parenteral injection of a macrolide antibiotic, tilmicosin, for control of bovine respiratory disease (BRD) in cattle at low-to-moderate risk of developing BRD. The objective of this study was to evaluate whether NORS was non-inferior to tilmicosin for control of BRD in cattle at high-risk of developing BRD (the target population for many BRD control programs). High-risk Angus-cross heifers (n=840) were randomly allocated to 2 treatment groups on arrival at a feedlot and received either NORS or tilmicosin for BRD control. Non-inferiority was assessed by calculating the difference in prevalence of heifers diagnosed with BRD during the first 40 d after arrival between NORS and tilmicosin treatment groups. The non-inferiority margin (δ) was set at 8.5%. Thirty-six and 19% of heifers were diagnosed with BRD in the NORS and tilmicosin groups, respectively. Because the lower bound of the 2-sided 95% confidence interval (CI) of the difference in BRD prevalence between the 2 treatment groups (17%; 95% CI=11-23%) was higher than δ, an inferiority of NORS was concluded. Although on-arrival nasal administration of NORS can be viewed as a more rational control strategy than parental injection of antibiotics, further research is needed to improve NORS efficacy before it can be recommended to prevent BRD in high-risk cattle.