Weaning piglets: interaction of dietary protein with intestinal microbiota and gut health
The animal Article of the Month for July is entitled ‘Impact of dietary protein on microbiota composition and activity in the gastrointestinal tract of piglets in relation to gut health: a review’
The microbial ecosystem of the intestinal tract of pigs is influenced by various factors. Among these, dietary composition has been identified as one of the most important. Changes in diet composition, as they occur e.g. during the weaning period, when the young piglet is separated from the mother and has to adapt from mother’s milk to solid feed, have major effects on the microbial ecosystem. As a result, the intestinal microbiota may be disturbed, which in consequence alleviates access of pathogens, and leads to an increased risk of infectious diseases and diarrhoea.
Improving intestinal health through specific dietary ingredients or supplements which are suitable to benefit the microbial ecosystem has gained increasing interest, especially since in-feed antibiotics have been banned in Europe. For example, promotion of beneficial Lactobacillus species and bifidobacteria by prebiotic substances (e.g. inulin, oligosaccharides) has become one major option. Beneficial properties of lactobacilli and bifidobacteria include e.g. an increased resistance against colonization of the intestine with pathogens. A further beneficial effect is the increased production of short-chain fatty acids, which can be used as an energy source for intestinal epithelial cells.
On the other hand, fermentation of protein results in the production of various potentially toxic products, such as amines and ammonia. Furthermore, excessive protein intake has been shown to stimulate the growth of potentially pathogenic species such as Clostridium perfringens. Meanwhile, numbers of beneficial bifidobacteria seem to be reduced due to increased protein intake.
The present paper reviews several studies investigating the effect of changes in protein supply and protein quality on the microbial ecosystem of piglets. Although results are not always consistent, it appears that avoiding excessive amounts of protein may reduce post-weaning diarrhoea and inhibit the growth of pathogenic bacteria. This is of special importance for piglets reared under nutritional and environmental stress conditions.
According to several studies, feeding a reduced amount of dietary protein and, at the same time, supplementing the piglet’s diet with fermentable carbohydrates, has been proven to be a successful option to suppress protein fermentation. In addition, the source of dietary protein may also affect the composition and metabolic activity of the intestinal microbiota. There is evidence that the use of highly digestible protein sources may reduce growth of protein-fermenting and potentially pathogenic species. The practical relevance of these studies, however, can be questioned, as these protein sources such as casein are hardly used in diet formulation of pigs due to their low cost-efficiency. Thus, Rist and co-workers highly recommend for future studies to assess alternative protein sources such as protein isolates or concentrates of plant and animal origin.
In conclusion, developing feeding strategies suitable to influence microbial ecology of the intestine in a beneficial way seems to be a promising approach. However, further studies are warranted to address the interaction of dietary protein with the intestinal microbiota.
Authors: V. T. S. Rist, E. Weiss, M. Eklund and R. Mosenthin
The animal Article of the Month is selected by the Editor-in-Chief and is freely available for one month.