Alternatives to conventional antibiotics for the prevention and treatment of commonly occurring diseases in feedlot cattle.

Antibiotic-resistant bacteria are a problem in human medicine. The development of antibiotic resistance in bacteria in feedlot cattle could have negative effects on their health and welfare and there is a theoretical possibility of transmission of antibiotic-resistant bacteria from food animals to humans. Alternatives to conventional antibiotics in feedlot health management could reduce the selective pressure for the development of antibiotic resistance. This review assesses the evidence supporting potential alternatives to conventional antibiotics in the prevention and treatment of diseases in feedlot cattle, including nitric oxide, plant extracts, supplemental yeast or yeast products, bacterial probiotics, organic acids, bacteriophages and non-specific immunostimulants. Further research is warranted with lactate utilising bacteria, the organic acid malate, bacteriophages and the non-specific immunostimulants ß-1,3 glucan and those based on pox viruses. However, none of the alternatives to conventional antibiotics investigated in this review have sufficient supporting evidence to date to justify their use with feedlot cattle. Frequently, statistically weak results and studies without negative controls are cited as support for similar studies. The health and welfare of feedlot cattle are dependent on the use of products that have robust supporting data to ensure efficacy and to avoid adverse outcomes.

Health and production of feedlot cattle following supplementation with urea-molasses in starter pens.

OBJECTIVE: To determine the effect of providing a urea-molasses supplement to cattle during feedlot introduction on average daily gain, carcase weight and bovine respiratory disease (BRD) morbidity and mortality. METHODS: Commercial mixed sex, mixed breed cattle (387.4 ± 0.2 kg) were systematically allocated to receive 2.1 L/animal of urea-molasses during feedlot introduction (n = 2307) or remain untreated (n = 2336). Cattle remained in the feedlot for an average of 40 days until reaching slaughter weight. Body weight data was collected prior to feedlot induction and all cases of BRD morbidity and mortality were determined during feeding. Hot standard carcase weight and P8 fat thickness were determined at slaughter. RESULTS: Average daily gain (1.94 ± 0.06 vs 1.93 ± 0.06, P = 0.650), BRD incidence (6.46% vs 5.53%, P = 0.183) and BRD mortality (0.17% vs 0.21%, P = 0.752) did not differ between supplemented and unsupplemented cattle. The BRD incidence was higher (P = 0.017) when cattle without permanent incisors were supplemented with urea-molasses (7.26%) compared with unsupplemented cattle (5.26%), and was also higher in steers compared with heifers (12.7% vs 7.8%, P < 0.001) and higher in cattle purchased from saleyards compared with cattle purchased off paddocks (12.4% vs 5.7%, P < 0.001). CONCLUSIONS: Health and production were not significantly improved following supplementation of cattle with urea-molasses during feedlot introduction. BRD incidence was, however, significantly related to cattle sex and source. Further research is required to understand the relationship between feeding high non-protein nitrogen sources and BRD morbidity in young cattle.