Molting is used to increase productivity in the second laying cycle of commercial laying flocks. We report here the applicability of whole grain of bitter vetch as an alternative method for molt induction in laying hens. A total of 120 laying hens were molted by feed withdrawal (FW), a high-Zn diet (HZn), a moderate-Zn and Ca-P-deficient diet (MZn-CaP), or whole grain of bitter vetch (BV). Egg production ceased first in FW-treated hens and last in MZn-CaP-treated hens (P < 0.05). The rest period was longer (P < 0.05) in hens exposed to the BV diet, which proved to be comparable with the FW treatment for postmolt egg production. Egg mass for 4 to 16 wk after the molting was greater (P < 0.05) for hens molted by BV than hens molted by the MZn-CaP diet. Egg weight and yolk color were not (P > 0.05) significantly different among various molting induction methods. Albumen height and Haugh unit of eggs from hens molted by BV, for the most part of the experimental period, were significantly (P < 0.05) greater than for birds on the MZn-CaP diet and unmolted hens. In conclusion, use of BV grain as a single dietary ingredient proved to be effective in molt induction and improving postmolt egg production and internal egg quality when compared with unmolted hens.
