Effect of dietary energy levels in Hy-Line Brown laying Hens during the last production phase

Abstract

Diets with 2800 and 2900 kcal of ME/kg was evaluated to determine their effect on weight gain and egg quality parameters at the end of the production cycle in hy-Line Brown hens separated into two weight groups weights: <2200g and> 2200 g. A group of 960 hens with 75 weeks of age was employed distributed in a Random Complete Blocks Design with a bifactorial arrangement. Data were analyzed by analysis of variance and for the comparison of treatment means, the Duncan Significant Minimum Range test was used at a <0.05 and <0.01 probability both for the independent factors and for the bird weight interaction and diet energy level. Data about consumption, egg production, feed conversion and abdominal fat were collected. Egg quality was determined by weight records, albumen height, color, freshness, resistance, and thickness by using the digital method with laser irradiation in the digital Egg Tester DET-600. The results showed effects on hens weight upon consumption and weekly weights, lighter hens consumed less and resulted in lower weekly weights compared to heavier hens (P <0, 01), however, cumulative weight gain was not affected by the hen weight factor and energy level of diets (P> 0, 005). Heavier birds accumulated more abdominal fat at the end of the laying period than the less heavy birds (P <0.01). Egg production and feed conversion did not suffer variations due to the effect of both factors, although egg weight was affected only by bird weight (P <0.01). On the other hand, egg color shows variations depending on the energy level of the diet; while the freshness, resistance and thickness of the egg were not affected by any study factor (P> 0.05). it would be feasible to reduce the energy value of the diet without affecting the productive performance of the birds.