ARS | Publication request: Fiber utilization and enzymes in swine diets

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 22, 2012
Publication Date: October 22, 2012
Citation: Kerr, B.J., Shurson, G.C. 2012. Fiber utilization and enzymes in swine diets. Proceedings of GenTech Industries Group Conference. 95-112.

Technical Abstract: Plant carbohydrates can be classified into three categories: 1) simple sugars and their conjugates (glucose, fructose, etc.); 2) storage reserve compounds (starch); and 3) structural carbohydrates (cellulose, hemicellulose, etc.). Simple sugars and storage compounds are primarily digested in the upper gastrointestinal tract of pigs, although not completely, while structural carbohydrates are only partially degraded by the microflora in the cecum and large intestine. With pigs being able to utilize moderate, but not high levels of fiber, there is a need to increase the ability of the pig to utilize the energy associated with the structural carbohydrates contained in various ‘high-fiber’ co-products. Application of enzymes in an effort to improve nutrient digestibility of plant-based feed ingredients for swine and poultry has been studied for decades. However, with a large diversity and concentration of chemical characteristics existing among plant-based feed ingredients, as well as interactions among constituents within feed ingredients and diets, improvements in nutrient digestibility and pig performance from adding exogenous enzymes to growing pig diets depends on understanding these characteristics in relation to enzyme activity. Essentially, the enzyme must match the target substrate(s), there may need to be a ‘cocktail’ of enzymes to effectively breakdown the complex matrixes of fibrous carbohydrate structures, and there must be some negative role that these substrates have on nutrient digestibility or voluntary feed intake. With the inverse relationship between fiber content and energy digestibility being well described for several feed ingredients, it is only logical that development of enzymes that degrade fiber, and thereby improve energy digestibility or voluntary feed intake will have a greater likelihood to be beneficial, both metabolically and economically. The results of our study suggest that although some of the enzyme/additive products evaluated had variable, but small effects on nutrient digestibility, none of these products were effective in improving starter and finishing pig growth performance when fed nutritionally adequate corn-soy diets containing 30% dried distillers grains with solubles (DDGS).