Manipulation Of The Hindgut Fermentation

In order to maintain a healthy intestinal microflora for efficient animal growth, growth promotants, primarily in the form of antibiotics, have been therapeutically fed to livestock for several decades. This practice is suspected to be linked to development of antibiotic-resistant microorganisms. Thus, alternatives to antibiotics are being sought.[3] These include supplementary enzymes to diets, organic acids, prebiotics, and probiotics. However, many of these alternatives are viewed with skepticism because the results obtained are variable and few have been studied sufficiently to adequately explain a mode of action.

Other efforts to increase animal growth efficiency are the use of genetically modified grains and forages that contain appropriate hydrolytic enzymes in vacuoles or in the cytosol to be released after crop harvest and animal consumption. These enzymes will assist microbial enzymes in extracting nutrients for animal growth. Recent studies have also demonstrated that it is possible for transgenic mice to produce key microbial enzymes that degrade fiber or plant phosphorous more efficiently.1-8-1 Generation of transgenic animals that secrete xylanase from the pancreas suggests that this may prove to have a dual benefit. Intestinal secretion of xylanase by swine would enhance nutrient absorption and the xylooligosac-charide products from xylanase action would enrich Bifidobacterium spp. in the intestine, thus providing a more favorable intestinal environment.

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