Effect of aerosolized bacterial lysate on development of naturally occurring respiratory disease in beef calves

Abstract

Background: Bovine respiratory disease (BRD) is a major problem affecting beef cattle after arrival to feedlots. Alternatives to antibiotics are needed for prevention. Hypothesis: Stimulation of pulmonary innate immune responses at the time of arrival to a feedlot reduces the occurrence and severity of BRD. Animals: Sixty beef steers at high risk of BRD. Methods: Randomized, double-blinded, placebo-controlled study. Calves received saline or a lysate of Staphylococcus aureus and Escherichia coli by aerosol, at 16 hours after feedlot arrival. Calves were monitored for 28 days for disease outcomes and levels of Mycoplasma bovis and Mannheimia haemolytica in nasal swabs. Results: Death from M bovis pneumonia was significantly greater in lysate-treated animals (6/29, 24%) compared to controls (1/29, 3%; odds ratio = 10.2; 95% confidence interval [CI] = 1.1-96.0; P = .04). By 28 days after arrival, 29/29 lysate-treated calves had ultrasonographic pulmonary consolidation compared to 24/29 control calves (P = .05). Lysate-treated calves had lower weight gain compared to control calves

The Prevalence, Coexistence, and Correlations between Seven Pathogens Detected by a PCR Method from South-Western Poland Dairy Cattle Suffering from Bovine Respiratory Disease

“…Taking into consideration the shown bacterial agents, prevalence, and scientific reports about opportunistic pathogens, it is important to bear in mind that despite the very high prevalence of P. multocida and the high frequency of coinfection with P. multocida and M. haemolytica in some of the calves we examined, these agents were not necessarily responsible for the presence of disease symptoms [ 8 , 17 , 28 , 51 , 52 ]. Nevertheless, being components of the respiratory tract flora, when the clinical form of the disease occurs (regardless of whether they are the cause) due to the use of antimicrobials in the treatment and control of BRD, they acquire resistance to the antibiotics used, becoming a reservoir of resistance genes [ 2 , 14 , 36 , 38 , 52 , 53 , 54 ].…”