Phase Feeding for Laying Hens: Effect of Protein and Essential Amino Acids on Egg Quality and Production

The effect on egg quality of reducing the dietary protein and methionine+cystine (experiment 1) and methionine+cystine, lysine and protein (experiment 2) for laying hens with increasing age was studied. In experiment 1, four groups of laying hens were fed different diets in one to three feeding-phases as follows, with protein and methionine+cystine, respectively, in g/10 MJ ME. Group A: 146 and 6.6 at 20-35 weeks (LP1), 136 and 6.0 at 36-74 weeks (LP2). Group B: 156 and 6.6 at 20-35 weeks (K1), 148 and 6.0 at 36-45 weeks (K2), 121 and 4.8 at 46-74 weeks (LP3). Group C: K1 at 20-35 weeks, K2 at 36-74 weeks. Group D: LP1 at 20-74 weeks. In experiment 2, two hen lines (Lohmann Brown and ISA Brown) were fed diets with the following contents of methionine+cystine, lysine and protein, respectively, in g/10 MJ ME. Group A: 4.5, 5.3 and 120 at 21-71 weeks (N). Group B: 5.0, 5.8 and 132 at 21-35 weeks (N10), N at 36-71 weeks. Group C: 5.4, 6.4 and 144 at 21-35 weeks (N20), N10 at 36-45 weeks, N at 46-71 weeks. Group D: 5.9, 6.9 and 156 at 21-35 weeks (N30), N20 at 36-45 weeks, N10 at 46-71 weeks. Egg production and feed intake were registered, and the diets were analysed for nutritional composition. Eggs were collected in each phase for each group for quality analysis, including egg weight, shell weight, shell percentage, albumen height, Haugh unit and shell colour. In experiment 1, no differences in production traits between the groups were observed. In phase 3, group B had an overall lower egg weight, but increased albumen height. In experiment 2, group D had the highest egg output. The egg weight increased and shell percentage and albumen quality decreased with increasing dietary amino acid and protein content, a situation which was especially evident in the first phase at 21-35 weeks of age.