Using direct-fed microbials to protect calf health and promote immune function is addressed in a new publication by the Bovine Alliance on Management and Nutrition (BAMN).

According to the document, the terms “direct-fed microbials” and probiotics are used interchangeably. Probiotics are feed additives that contain microbial species that are considered to be non-pathogenic, normal flora. A probiotic is defined as “a live microbial feed supplement which beneficially affects the host by improving its intestinal microbial balance” (Heyman and Ménard, 2001). Probiotics are also referred to as “direct-fed microbials.” The U.S. Food and Drug Administration (FDA) defines direct-fed microbials as “…products that are purported to contain live (viable) microorganisms (bacteria and/or yeast).”

Direct fed microbials (or probiotics) refer to living organisms and should not be confused with prebiotics, compounds that promote the growth of gut bacteria (e.g., yeast culture, oligosaccharides) but are not living organisms. It is believed that gut bacteria have requirements for specific nutrients that may not be adequately provided by the animal’s diet. Therefore, feeding these nutrients may promote the growth of gut bacteria, thereby improving the microbial profile in the gut.

Synbiotics contain both a probiotic and prebiotic, which work together to promote healthy intestinal flora.

The goal of feeding probiotics is to support the growth of beneficial bacteria in the digestive tract to:

  • Inhibit the growth of infective bacteria
  • Improve digestion and nutrient absorption
  • Promote the structural and functional development of the immune system

The BAMN authors suggest that adding direct-fed microbials to milk or milk replacer may support calf intestinal integrity and overall health. They say most research has reported little effect of direct-fed microbials on animal growth or feed efficiency. Rather, improved intestinal bacterial flora may reduce the risk of diarrhea, particularly when animals are exposed to significant immunological, environmental or other stressors.

Read the full text of the BAMN Publication “Direct-fed Microbials (Probiotics) in Calf Diets."