The effect of fat type, carbohydrase, and lipase addition on growth performance and nutrient utilization of young broilers fed wheat-based diets

Department of Animal Science, University of Manitoba, Winnipeg, Manitoba, Canada.

A 2 x 2 x 2 factorial experiment was conducted to evaluate the effects of fat type (beef tallow [50 g/kg diet] or canola oil [50 g/kg of diet]), carbohydrase addition (none or carbohydrases [0.4 g/kg diet]), and lipase addition (none or lipase [0.2 g/kg of diet]) on growth performance and nutrient utilization of male broilers fed a wheat-based diet from 5 to 18 d. The carbohydrase supplement contained xylanase, glucanase, cellulase, and other enzyme activities. The experimental diets were formulated to be suboptimal in major nutrients and each was fed in a mash form to 10 replicate pens of 5 broilers per pen. Body weight gain was not affected by fat type but a poorer feed/gain ratio (P < 0.001) was noted for tallow-containing diets. Regardless of fat type, carbohydrase enzyme supplementation improved (P < 0.001) BW gain and feed/gain ratio. There was no effect of lipase addition on chicken performance and nutrient utilization. When compared with canola oil, tallow-containing diets had a lower (P < 0.001) apparent fat digestibility and consequently a lower dietary AMEn content. Carbohydrase enzyme addition improved (P < 0.001) fat, starch, nitrogen, and nonstarch polysaccharide (NSP) digestibilities in the small intestine, improved AMEn, and reduced (P < 0.001) jejunal digesta viscosity in both fat types. Carbohydrase supplementation increased water-soluble (P < 0.001) and decreased water-insoluble (P < 0.001) NSP concentrations in the small intestine. The interaction between fat type and carbohydrase addition was only significant for fat digestibilities, with greater improvements seen for diets containing tallow. Significant interactions between carbohydrase addition and intestinal segment were noted for fat, starch, nitrogen, and NSP digestibilities, with the enzyme effects being greater in the jejunum than the ileum. It is evident from the present study that an appropriate carbohydrase preparation could eliminate the negative effects of soluble NSP on animal fat utilization in a wheat-based broiler diet.

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