Effects of Different Forced Molting Methods on Egg Production and Egg Quality Traits

Abstract

This study was conducted to compare fasting and high dietary zinc as procedures to induce a forced rest of laying lens. Roos Brown laying hens in sixty-eight weeks of age were used for the experiment. Daily light was used in the molting period. The hens in the first three programs were fasted (for feed and water) and in the fourth and fifth groups consisted of feeing 10.000 ppm and 15.000 ppm dietary zinc for 9 days, respectively. Body weight lost of hens at 10 day after initiation of the treatment were found 14.72 %, 15.64 %, 15.39 % and 16.37 respectively. Each treatment resulted in a sharp drop in egg production, but egg production of the first group declined at slightly slower rate. Hen day egg production of the treatment groups were found 7.19, 3.22, 2.61, 4.73 and 5.65 eggs of the resting period and 108.30, 109,21, 114.86, 108.63 and 113.06 eggs for the second laying period (in 161 days). There were no significant differences egg production among the treatments. Very low mortality was noted in all proups with no apparent differences. For all proups, viabilities were 94.99 %, 96.69 %, 96.23 %, 98.23 % an 96.38 % at the resting period; and 94.88 %, 96.87 %, 95.52 %, 96.92 and 92.77 % at the second laying period. In all groups, egg weight and shell thickness were found 68.83, 68.10, 68.25, 69.07 and 69.12 g; 335.27, 320.72, 337.67, 320.63 and 336.45 µ, respectively. Egg quality variables, breaking strenght, shell thickness and yolk indexes were significantly different (P