Effects of milk fermented products : a scientific basis to study microbial probiotics in the pig

Abstract

One of the main functions of gastrointestinal microflora is to protect the host against pathogenic exogenous bacteria. Although it appears stable, the microflora balance can be disturbed by several husbandry practices such as weaning, a change in feed, a housing change or a regrouping of animals.

Microbial probiotics are feed additives constituted by viable micro-organisms (Lactobacillus Sreptococcus andBacillus) which should improve the microbial balance and contribute to normal digestive functions. However, their modes of action have not been clearly demonstrated. It has also been demonstrated that the lactic flora of yogurt or fermented milk exerts beneficial effects on the intestinal microbial balance. These products could be considered as probiotics for humans. For example, yogurt micro-organisms improve lactose digestion in lactase deficient subjects. It has also been demonstrated that continuous feeding of fermented milk products improves gut microbial balance and has beneficial effects against diarrhoea. Furthermore, Lactobacilli ingestion stimulates the antigenic recognition through interferon production and increases IgG synthesis.

Microbial probiotics have been mainly tested on rearing performances of weaned piglets. However, no beneficial effects have been reported after many performance trials. If the effects of microbial probiotics on growth performance of young animals are questionable, it appears essential to plan physiological, microbiological or immunological experiments to gain a better understanding of microbial probiotic mechanisms and to provide a scientific background to these newly developed feed additives. Some authors have already initiated research on their mechanisms and have noticed a positive effect of several Lactobacillus strains on lactic and coliform population balances. They have also studied the effects of a probiotic based on "Lactobacillus acidophilus", "Lactobacillus plantarum" and "Streptococcus faecium" or a probiotic constituted by the "Sporolactobacillus" P44 strain on nutritive functions of the digestive tract and the effect of a probiotic based onLactobacillus casei and Lactobacillus bulgaricus on some immunological functions.