Metabolism and Nutrition: General Posters

The recommendations of energy levels for laying hens vary greatly between the strain manuals and also between strains manuals and tables of research institutions. The use of inadequate levels of energy can lead to productivity losses and low efficiency of energy use. To establish mathematical models for yield response of young laying hens to different levels of AMEn and evaluate the influence of energy levels on energy use by these birds, an experiment was conducted with 1200 Dekalb White hens, 23 to 40 weeks of age, housed in conventional cages. These birds were divided into 5 groups according to the level of dietary AMEn: A 2700 kcal/kg, B 2775 kcal/kg, C 2850 kcal/kg, D 2925 kcal/kg, and E 3000 kcal/kg, with 6 replicates per group. The experimental design was randomized and data were submitted to polynomial regression. There was a linear decrease effect in egg production with increased levels of AMEn, being found the equation y = −0.0183376x + 141.805 (R2 = 0.85). No significant effects of AMEn levels on egg weight, live weight of poultry and livability were found. The egg mass was influenced by levels of AMEn: y = −0.012928x + 90.124850 (R2 = 0.88). The regression equation that best explains the effect on the levels of AMEn on feed intake is: y = −0.033564x + 188.35559 (R2 = 0.96), there is no effect of AMEn levels on consumption of AMEn. The feed conversion was influenced by the levels of AMEn: y = −0.000208x + 2.333480 (R2 = 0.90). The feed conversion per egg dozen was also influenced by levels of AMEn being the equation y = −0.000196x + 1.801573 (R2 = 0.87) indicating a linear improvement in feed conversion per egg dozen with the increase of the levels of AMEn . With increasing levels of AMEn there is worsening in the efficiency of energy conversion: y = 0.001141x 1.703423 (R2 = 0.96). There is a linear decrease in egg production and feed intake by young hens with the increase of AMEn levels from 2700 to 3000 kcal/ kg, while the other productive parameters remain unaffected regardless of the level used. Therefore the level of 2700 kcal/kg diet can be recommended for young hens.