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Alternatives to Antibiotics
Increased regulation of feed grade antibiotics has resulted in a vast array of products to be introduced and has compelled researchers to explore strategies that improve performance without the use of antibiotics. There are a number of techniques and strategies available to help cattle producers replace antibiotics, including non-antibiotic feed additives. Feed additives are defined as dietary ingredients that produce a desirable response in animals in a non-nutritive role. Several feed additives contain nutrients, however, they are not fed to meet an animal requirement, rather, they are fed to alter ruminal or post-ruminal metabolism to enhance nutrient utilization and animal productivity. Feed additives act in many different ways – some affect the ruminal environment, others impact post-ruminal digestion and metabolism; and still others act to depress subclinical problems (acidosis, liver abcesses, heat stress) in which there are no visible disease symptoms or to improve immune response. A reduction in human pathogenic bacteria and benefits to health, safety, and quality of meat products may also result from use of feed additives. Because of the benefits for the host ruminant in terms of health and energy utilization, improvements in the microbial ecosystem and ruminal function have been a goal for ruminant nutritionists and microbiologists for decades and will be the primary focus for this presentation. The mode of action and effectiveness of several antibiotic alternatives will be discussed, including methane inhibitors, essential oils, and yeast and bacterial probiotics and direct-fed microbials. Several of these feed additives are effective; however, their practical implementation has been hindered by the variability in animal responses under experimental conditions and increased cost. In addition, while some of these strategies may be used to replace antibiotics, many of them may be effective in conventional systems in conjunction with antibiotics to enhance animal health and productivity. Thus, producers should evaluate potential strategies for use of feed additives under specific feeding and economic conditions.
Keywords: antibiotic alternative, feed additive, ruminal function