Bio-Mos: Opportunities for improving health and production?
Enteric diseases are the greatest cause of illness and death in calves (NAHMS, 1996). Producers often treat calves with antibiotics therapeutically even though most of the causative agents for diarrhoea are not responsive to antibiotics. Additionally, most commercial milk replacers contain sub-therapeutic levels of antibiotics in an attempt to prevent enteric diseases.
In pigs the greatest cause of mortality was respiratory disease accounting for 28.9 percent of nursery deaths and 39.1 percent of deaths in grower/finisher pigs.
The newborn animal is most susceptible to enteric pathogens due to development of neonatal gastrointestinal microflora. Ruminants, like other mammals, are born devoid of indigenous intestinal microorganisms. During transport through the vagina, some bacteria are acquired by the neonate. This route may provide the initial inoculum of the newborn gastrointestinal tract, since predominant bacteria in the vagina include lactic acid bacteria. After passage through the birth canal, the neonate may become contaminated and subsequently colonised by fecal organisms such as Escherichia coli.
A threat to the neonate stems from the fact that the initial gastrointestinal tract pH is near neutrality. Since the microbial population is in transition and extremely sensitive at this time, it is susceptible to colonisation from pathogenic bacteria.
For this reason, enteric diseases are the greatest cause of illness and death in calves (NAHMS, 1996). These problems occur despite the fact that most commercial milk replacers contain sub-therapeutic levels of antibiotics in an attempt to prevent enteric diseases.
Mannan oligosaccharide (MOS) is a complex carbohydrate consisting of polymers of mannose and mannose derivatives. Carbohydrates and oligosaccharides are now being utilised for their role in nutrition and immunity.
One way to prevent pathogens from causing disease is to prevent them from attaching to the epithelial cells in the gut. Mannan oligosaccharide has been successfully used to prevent this attachment by providing the bacteria a mannose-rich receptor that serves to occupy the binding sites on the bacteria and prevent colonisation.
Several studies have been conducted examining the role of mannans and their derivatives on binding of pathogens to epithelial cells in the GI tract. E. coli with mannose-specific lectins did not attach to mammalian cells when mannose was present (Salit and Gotschlich, 1977).
In several calf trials, calves receiving MOS in milk replacer formulations had lower fecal coliform and E. coli concentrations than calves receiving unsupplemented milk replacers (Table 1).
MOS also plays a role in animal immunity. Because carbohydrates project from cell surfaces, they often form the most important antigenic determinants of certain cell types such as bacteria, molds and viruses.
To summarise, MOS provides benefits to supplemented animals via two basic mechanisms: (1) Agglutination of bacteria which may cause enteric disease in the animal. (2) Modulation of immune function. Vaccination titers have also demonstrated improvements with MOS inclusion in the diet. In an era under the threat of withdrawal of antibiotic supplementation in livestock feeds, alternatives that provide cost-effective benefits similar to traditional growth promotants demand a closer examination from producers. MOS have been shown to reduce disease incidence and improve calf performance.
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Article made possible through the contribution of Venture Laboratories, Inc.