Influence of energy concentration and standardized ileal digestible lysine content of the diet on performance and egg quality of brown-egg laying hens from 19 to 59 weeks of age

An experiment was conducted to determine the effects of the AMEn concentration and standardized ileal digestible lysine (SID Lys) content of the diet on performance and egg quality of brown Classic Lohmann hens from 19 to 59 wk of age. There were 8 treatments organized as a 2 × 4 factorial with 2 AMEn concentrations (2,750 and 2,650 Kcal/Kg) and 4 levels of SID Lys (0.68, 0.72, 0.76, and 0.80%) in the diet. All other indispensable amino acids were formulated according to the ideal ileal protein concept. Each treatment was replicated 9 times and the experimental unit was a cage with 9 hens. The experiment lasted for 10 periods of 4 wk each. All birds had free access to feed and water throughout the trial. Production data (egg rate, feed intake, egg weight, egg mass, FCR, BW gain, and mortality) were collected by period. Egg quality traits (egg weight, Haugh units, and egg shell resistance to breakage) were measured in 8 eggs randomly select from each replicate the last 2d of each of the 10 experimental periods. Data were analyzed as a completely randomized design using the mixed procedure of SAS with energy concentration, level of SID Lys and the interaction as main effects. In addition, treatment sum of squares of the level of SID Lys, was partitioned into lineal (L) and quadratic (Q) effects. All differences were considered significant at P < 0 .05. No interactions between AMEn and SID Lys were found for any trait and therefore, only main effects are presented. An increase in the energy content of the diet, improved egg weight (P < 0.001) and FCR (P < 0.05) but did not affect any of the other variables studied. The diet with the higher energy content had more added fat than the diet with the lower energy content (3.5% vs. 1.3%). Consequently, the higher level of added fat might have resulted in the improvement in egg size observed. An increase in the level of SID Lys from 0.68% to 0.80% improved linearly egg weight (P < 0.05) and egg mass production (P < 0.05) but did not affect ADFI, FCR, BW gain, or hen mortality. The level of SID Lys of the diet did not affect egg shell resistance to breakage or albumen quality. In conclusion, an increase in the energy content of the diet from 2,650 to 2,750 Kcal AMEn did not affect the number of eggs produced but increased egg weight. Hens require no more of 0.68% digestible Lys in the diet (736 to 752 mg SID Lys per day for the low and high energy diet respectively) to optimize egg production. However, if the objective is to maximize egg weight or egg mass production, higher levels of SID Lys might be required