Abstract
The objective of this study was to evaluate the effect of the supplementation of xylanase in diets with reduced energy level on the apparent metabolizable energy corrected for nitrogen, determined with laying hens at 14, 36, 60 and 80 weeks of age. Four digestibility trials were conducted, using 80 Hy-line W36 laying hens aged 14, 36, 60 and 80 weeks of age. Birds were distributed in a completely randomized design in 2 × 2 factorial arrangement (energy level × inclusion of xylanase), totaling four treatments with 10 replicates of two birds each. Treatments were: positive control (balanced diet for their age); positive control + xylanase; negative control (diet with reduction of 100 kcal/kg in the level of metabolizable energy); and negative control + xylanase. Xylanase, produced by microorganism Trichoderma reesei, was added to the diets at 100 g/t (16,000 BXU/kg) for diets fed at 14 weeks and 75 g/t for diets of 36, 60 and 80 weeks (12,000 BXU/kg). The data obtained were subjected to analysis of variance at 5% probability. Supplementation of xylanase promoted higher values for AME (apparent metabolizable energy) and AMEn (apparent metabolizable energy corrected for nitrogen) determined with 80-week-old laying hens, subjected to diet with energy level according to the nutritional requirements for their age. Supplementation of xylanase increases the matabolizability coefficient of the dietary crude protein and improves the nitrogen retention of laying hens at 14 weeks. In addition, xylanase associated with adequate levels of dietary energy promotes higher values for AME and AMEn determined with laying hens at 80 weeks of age.
Highlights
It is known that, in laying hens, approximately 20% of energy is used for production; the decision of the amount to be provided is fundamental, since the bird will preferentially direct the energy for maintenance and decrease the production if the input is insufficient
There was interaction (P
Xylanase, associated with the reduction of dietary energy, reduced the metabolizability coefficient of dry matter at 36 weeks of age, but promoted better results (P
Summary
In laying hens, approximately 20% of energy is used for production; the decision of the amount to be provided is fundamental, since the bird will preferentially direct the energy for maintenance and decrease the production if the input is insufficient. A diet deficient in energy can cause a reduction in the growth of the bird, as well as decrease in the laying rate and weight loss (Leeson & Summers, 1997). Non-starch polysaccharides (NSP) stand out as one of the anti-nutritional factors. Maize is an -digested ingredient, there is evidence suggesting the presence of starch resistant to digestion, which may limit the value of corn energy and of the dietary energy (Slominski, 2001). It is known that enzymes can hydrolyze polysaccharides that prevent the digestion of starch grains and protein, making these compounds available for digestion by the action of endogenous enzymes (Bedford, 1996)
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