Effect of Molting White Leghorn Hens on Egg Shell Pimpling and Shell Quality
Two experiments were conducted to evaluate the effect on eggshell pimpling of molting 85-wk-old White Leghorn hens. Experiment 1 used 120 hens. In Experiment 2, 25 hens consistently laying pimpled shell eggs (PS group) and 25 laying smooth shelled eggs (SS group) were selected. Both groups of hens were molted and observed for seven periods of 28 days and egg production and feed consumption determined pre and postmolt. Shell quality was evaluated for degree of shell pimpling [by scoring eggs from 1 (smooth) to 5 (very pimpled)] and for specific gravity, shell deformation, percentage shell, percentage shell membrane, and eggweight. In Experiment 1, pimple score declined from 3.7 premolt to 2.3 postmolt period one. By period seven, pimple score increased to 3.3. No clear trend was found for specific gravity, shell deformation, percentage shell, or percentage shell membrane. In Experiment 2, pimple scores for the PS group remained significantly higher than SS group scores and were at an unacceptable level (4.8 premolt and 3.6 postmolt).
Samples of eggshell membranes from Experiment 2 were obtained either pre or postmolt and lyophilized for analysis of nitrogen and amino acids. Average percentage protein values were 82.8 and 84.1% for premolt and postmolt samples and 81.3 and 85.7% for PS and SS groups, respectively. No significant differences were found in protein percentages. No large differences were shown between amino acid compositions of shell membranes from pre and postmolt or PS and SS groups. The PS group membranes had significantly higher phenylalanine values than those of the SS group. Lysine values were higher postmolt than premolt.