Preventative programs for respiratory disease in cow/calf operations

Cost of bovine respiratory disease in preweaned calves on US beef cow-calf operations (2011-2015)

OBJECTIVE To develop a partial budget analysis of direct costs associated with bovine respiratory disease (BRD) in preweaned calves on US beef cow-calf operations and identify factors that strongly influence those costs. DESIGN Risk analysis model. ANIMALS US preweaned beef calf inventory from 2011 through 2015. PROCEDURES A stochastic simulation model was developed by use of a computer spreadsheet and add-in software. Input data were obtained from the USDA, peer-reviewed literature, and a survey of beef cow-calf producers. A simulation consisting of 10,000 iterations was used to account for either uncertainty or variability in model inputs. The median (90% confidence interval) was reported for each output variable. Global and local sensitivity analyses were performed to identify the most influential factors and quantitatively evaluate the effects of inputs on the estimated costs. RESULTS From 2011 through 2015, BRD in preweaned calves cost the US beef cow-calf industry approximately $165 million annually, of which costs associated with the death, treatment, and decreased weaning weight of BRD-affected calves were approximately $126, $25, and $15 million, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Although BRD in preweaned calves may have a fairly small effect on the total gross income for the US beef cow-calf industry as a whole, it can have a substantial adverse effect on the net profit of BRD-affected herds. The model developed provided important information regarding the cost of BRD in preweaned calves on US beef cow-calf operations and identified factors that had an import effect on those costs.

Management- and housing-related risk factors of respiratory disorders in non-weaned French Charolais calves

Our aim was to determine at calf-batch level the management- and housing-related risk factors of respiratory disorders in non-weaned Charolais calves. Farmers recorded cases according to the definition provided i.e. the association of at least one respiratory sign and, in the same calf or another calf of the same batch, at least one general sign on the same day or the day before. During farm visits, quality of farmers' records was checked and questionnaires were applied to gather farm and herd characteristics and to describe farming practices and housing facilities. Data were suitable for analysis for 172 batches where no metaphylactic treatment was implemented. Batches had great disparity in incidence of respiratory disorders. In the 120 batches with at least one case, the quartiles of incidence rate were, respectively, 0.95, 2.15 and 3.59 cases per 1000 calf-days at-risk. For risk-factor analysis, the statistical unit was the calf-batch located in a given batch. We used a ZINB model because (i) there was significant overdispersion of incidence rates of respiratory disorders (overdispersion test statistic of O=1049 (P<0.001)), (ii) probability was high that a two-group modelling process existed (Vuong statistic of V=2.44 (P=0.0073)) and (iii) the ZINB model fit significantly better than the ZIP model (likelihood-ratio statistic of 340.14 (P<0.001)). The risk was higher in open-fronted barns or in open barns compared to closed ones (incidence-rate ratios (IRRs): 1.9 and 1.8), in barns where no annual disinfection was implemented (IRR: 1.5) and in part slope with straw/part scraped and in part straw-bedded/part scraped barns compared to completely straw-bedded barns (IRRs: 1.9 and 1.6). Larger calf-batches were more at-risk than smaller batches (OR for the effect of an increase of 10 calves on the probability of a 0 count: 0.5).

The development of beef breeding bulls

Management of the bull battery will have a dramatic impact on profitability of the cow/calf enterprise. It is critical that young bulls be selected and developed to maximize longevity and productivity for the eventual buyer. Bulls must be structurally sound, healthy, and have adequate libido in order to service the required number of females. Once bulls complete their first breeding season, special care must be taken in order to ensure that they recover and regain needed body condition and pass a bull breeding soundness examination (BBSE). Mature bulls that have reached their genetic potential for growth require less intensive management, but the health program and annual BBSE cannot be overlooked. Mature bulls are also more likely to carry venereal disease and should be screened according to local disease incidence and state regulations. All bulls, regardless of age, should be observed early during the breeding season to ensure that they are physically capable of mounting and servicing females. The establishment of a complete management program, especially for young bulls, is essential to ensure that ranch resources are used efficiently, including maintenance of a high level of reproductive performance of the cow herd.

Effect of a quadrivalent vaccine against respiratory virus on the incidence of respiratory disease in weaned beef calves

We investigated the effect of vaccination of male beef calves (mean age ± S.D.: 158 ± 31days) against bovine herpes virus (BHV-1 or IBR virus), bovine respiratory syncitial virus (BRSV), bovine viral diarrhea (BVD) virus and para-influenza (PI₃) virus on the incidence of respiratory disease during the first forty days after weaning and entering a feed-lot in Portugal.

In May 2003, Mertolenga, Preta and mixed-breed calves from 10 different beef herds, were systematically assigned (by order of entrance in a chute) to two treatment groups, before moving to a common feed-lot. One hundred and twenty five male calves were vaccinated with a quadrivalent vaccine (Rispoval 4^®) and revaccinated after 21–27 days while 148 herdmates were injected with saline (0.9% NaCl) on the same occasions. The incidence and severity of clinical cases of “bovine respiratory disease” (BRD) were evaluated every day during the first 40 days after entering the feed-lot. Morbidity (3% vs. 14%) and mortality (0% vs. 4%) due to BRD were significantly lower in the vaccinated group. Ten days after revaccination, the calves were treated with an antimicrobial – ending the study – after an outbreak of BRD caused a high incidence of disease in the non-vaccinated group.

In conclusion, our results showed that Rispoval 4^®, a quadrivalent vaccine against respiratory viruses, under field conditions, reduces morbidity and mortality due to BRD in beef calves after weaning.

Efficacy of a quadrivalent vaccine against respiratory diseases caused by BHV-1, PI3V, BVDV and BRSV in experimentally infected calves

The efficacy of a quadrivalent vaccine against viral bovine respiratory diseases (BRD) was assessed in four experimental studies. Calves between 2 and 9 months of age were allocated to one of two treatment groups (n=9-15) and then received either the vaccine or sterile saline in two doses approximately 3 weeks apart. Three to 5 weeks after the second injection, animals were challenged experimentally with one of the viruses, bovine herpes-virus-1 (BHV-1), parainfluenza type-3 virus (PI(3)V), bovine viral-diarrhoea virus type 1 (BVDV), or bovine respiratory syncytial virus (BRSV) and were then monitored for at least 2 weeks. The administration of the vaccine was associated with enhanced antibody response to all four viruses post-challenge, with the reduction of the amount or duration (or both) of virus shedding in the BHV-1, PI(3)V, BVDV and BRSV studies and with an improvement of some clinical signs in the BHV-1 (nasal discharge, and rectal temperature) and the PI(3)V studies (abnormal respiration, and depression).

Health performance of feeder calves sold at conventional auctions versus special auctions of vaccinated or conditioned calves in Ontario

OBJECTIVE

To compare health performance during the first 28 days in the feedlot for vaccinated or conditioned feeder calves sold through special auctions in Ontario with health performance for calves sold through conventional auctions in the province.

DESIGN

Cohort study.

ANIMALS

12,313 calves sold through conventional and special auctions at the Keady Livestock Market during the fall of 1999 and 2000.

PROCEDURE

Buyers of calf groups were approached at the auction market or contacted by telephone and asked to record the number of calves requiring treatment for bovine respiratory tract disease (BRD) during the first 28 days after purchase.

RESULTS

211 calf groups (> or = 20 calves/group) were followed up for 28 days after purchase. Multivariate logistic analysis indicated that vaccinated calves purchased through special auctions were 0.68 (95% confidence interval, 0.50 to 0.93) times as likely to receive treatment for BRD as were calves purchased at conventional auctions and that conditioned calves were 0.22 (95% confidence interval, 0.12 to 0.38) times as likely to receive treatment. Groups that received antimicrobials by injection on arrival at the feedlot were 0.64 (95% confidence interval, 0.43 to 0.96) times as likely to be treated as were groups that did not.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that vaccinated and conditioned calves were less likely to receive treatment for BRD during the first 28 days in the feedlot; however, there was no difference in mortality rate.