Effect of Molting Method and Dietary Energy on Postmolt Performance of Two Strains of Single Comb White Leghorn Hens

Abstract

SUMMARY This experiment was a 4 × 2 × 2 factorial arrangement of 4 dietary energy levels (2,767, 2,806, 2,846, and 2,886 kcal of ME/kg), 2 molting methods (feed withdrawal and the low-salt diet), and 2 strains (Bovans White and Dekalb White). The objective of this study was to determine the effect of dietary energy and molting method on postmolt performance of 2 strains of commercial White Leghorns. Before the molt, Bovans and Dekalb hens were randomly divided into 2 groups. Feed was withdrawn from half of the hens (66 wk of age) for 9 d. A molt feed was fed from d 10 to 28. The other half of the hens was fed a low-salt diet for 28 d. After the molt, Bovans White hens (n = 720) and Dekalb White hens (n = 720) at 70 wk of age were randomly divided into 16 treatments (6 replicates of 15 birds per treatment). Bovans hens had significantly lower egg weight, percent of eggshell, egg specific gravity, and Haugh units than Dekalb hens, whereas Bovans hens had significantly higher egg production than Dekalb hens. Increasing dietary energy had no significant effect on any parameter other than yolk color. As dietary energy increased, feed conversion improved numerically from 2.13 to 2.05, resulting in a 3.8% improvement of feed conversion. With increasing dietary energy, hens adjusted feed intake, according to egg mass, to achieve the quantities of dietary energy (5.8 to 5.9 kcal) intake per gram of egg. An ideal dietary energy level for optimal postmolt performance and profits could not be determined for hens during phase 1 of the second cycle. Other than slightly reduced egg production and egg specific gravity during phase 1, feeding the low-salt diet to induce molt could be used as an alternative for the conventional feed withdrawal method.