Effects of the levels of methionine, linoleic Acid, and added fat in the diet on productive performance and egg quality of brown laying hens in the late phase of production.

Two trials were conducted to study the effect of reducing the methionine (MET, 0.36 vs. 0.31%), linoleic acid (LIN, 1.60 vs. 1.12%), and supplemental fat (SFAT, 3.0 vs. 1.1%) content of isoenergetic diets on the productive performance and egg quality of brown laying hens late in the production cycle. The 8 treatments were arranged factorially (2 x 2 x 2), with 6 replicates of 20 hens per treatment (Hy-Line, from 59 to 70 wk of age in trial 1, and Lohmann, from 56 to 75 wk of age in trial 2). Except for SFAT content, dietary treatment had little effect on laying hen performance and egg quality. The only effect of a reduction in MET content on hen performance was the decrease in the percentage of large and extra large eggs (79.8 vs. 85.9%; P < 0.05) from 60 to 67 wk of age in trial 2. A decrease in the level of SFAT reduced egg production (79.3 vs. 77.0%; P < 0.05), egg weight (66.3 vs. 64.9 g; P < 0.001), egg mass (52.5 vs. 49.8 g/d; P < 0.001), feed conversion ratio (2.26 vs. 2.36 kg of feed/kg of eggs; P < 0.001), and percentage of extra large eggs (13.1 vs. 8.2%; P < 0.05) in trial 1, but no significant differences were detected in trial 2. Reducing the LIN content of the diet from 1.60 to 1.12% did not affect any trait in either of the 2 trials. We conclude that reducing the level of SFAT from 3.0 to 1.1% might decrease productivity and the percentage of extra large eggs. However, a reduction in the MET level from 0.36 to 0.31% and in LIN from 1.60 to 1.12% did not affect any trait in hens late in the production cycle. Eggshell quality was not affected by any of the dietary treatments.