Effect of pre-peak feeding strategy on performance, egg quality, and tibiae mineralization of brown-egg laying hens from 27 to 62 week of age

We studied the influence of the nutritive value (AMEn, SID Lys, and Ca) of diets fed to pullets from 15 to 26 wk of age, on productive per-formance, egg quality, and tibia mineral content of brown egg-laying hens from 27 to 62 wk of age. Five feeding strategies were used. Three of them differed in the nutrient content of the diet fed from 15 to 18 wk of age: A) a pullet diet (2,700 kcal AMEn/kg, 0.61% SID Lys, and 1.0% Ca), B) a pre-lay diet (2,750 kcal AMEn/kg, 0.78% SID Lys, and 2.5% Ca), and C) a layer diet (2,750 kcal AMEn/kg, 0.78% SID Lys, and 3.8% Ca), respectively. The other 2 feed strategies (D and E) consisted in feeding the hens from 15 to 26 wk of age a diet low in energy (2,615 kcal AMEn/kg) and high in SID Lys (0.82%) diet with a medium or a high level of Ca (2.5 vs. 3.8%, respectively). After 18 wk (diets A, B, and C) or 27 wk (diets D and E) of age all the hens received the C layer diet to 62 wk of age. Each treatment was replicated 18 times and the experimental unit was an enriched cage with 10 hens for all traits. The experiment lasted for 12 periods of 4 wk each. Hen performance (egg production, egg mass, FCR, BW gain, and mortality) was controlled by replicate by period and cumulatively. Percentage of shell-less, broken, and dirty eggs were determined in all eggs produced. Egg quality, including Haugh units, shell thickness, shell strength, and shell weights in absolute (g) and in relative (%) terms, were determined by replicate in 8 eggs chosen at random for the last 2 d of each of the 12 periods. At 62 wk of age, one hen from 8 of the replicates per treatment was selected at random and sacrificed. The ash, Ca, and P content of these tibiae were determined. Data were analyzed as a completely randomized design with feeding strategy as main effect using the MIXED proce-dure of SAS. The Tukey test was used to make pairwise comparisons to separate treatment means. Feeding strategy did not affect any of the productive performance traits studied, except egg weight that tended (P = 0.079) to be greater in hens that were fed the high energy diets during the pre-peak period. Cumulatively, all shell quality variables studied were better (P < 0.05) in hens fed the 3.8% Ca diets during the experimental period than in hens fed 2.5% Ca or less, but Haugh units were not affected. At 62 wk of age the pre-peak feeding strategy did not affect the ash, Ca, or P content of the tibia. In summary, the use of a layer diet with 3.8% Ca from 15 wk of age onward, might improve shell quality traits during the entire egg cycle, without showing any negative effect on egg production