An Investigation of Different Molting Techniques with an Emphasis on Animal Welfare

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We experimented to evaluate the effect of a number of molting techniques that appeared to be less stressful than the conventional feed withdrawal (FW) method on postmolt performance. The molting techniques involved a continuous FW (T1, control group), 1 d FWfollowed by feeding a grape pomace (GP) diet containing 10 ppm thyroxine (T2) ad libitum, feeding a corn diet (T3) ad libitum, or the corn diet with an initial FW of 1 d (T4) or 2 d (T5), or regimens similar to T3, T4, and T5, respectively, in which the corn diet contained 10 ppm thyroxine (T6, T7, and T8). Induction of molting started at 66 wk of age and lasted until 30% body weight reduction (BWR) or 28 d—whichever came first. Postmolt performance information was collected up to 98 wk of age. The 30% BWR was obtained after 14 d FWwith T1 and after 16 d FWwith T2. Hens exposed to T6, T7, and T8 had a BWR of 26 to 29% after 28 d, and those exposed to T3, T4, and T5 had a BWR of 16 to 18% after 28 d from the start of induction of molt. Postmolt egg production (EP) was consistently greater for T1 and T2 than the other molting techniques. Other production traits, egg quality, and serum corticosterone, for the most part, were not different among various molting techniques. The results indicated that use of a GP diet plus thyroxine could support a similar postmolt performance as the conventional method of continuous FW. Unfortunately, the physiological response did not indicate that the use of a GP diet plus thyroxine was less stressful than the conventional method of continuous FW. Nevertheless, because use of the GP diet plus thyroxin supplies the hens continuously with some nutrients such as energy, protein, vitamins and minerals, etc., during induction of molt, this approach seems preferable due to ever-increasing public concern surrounding the hen welfare and the long duration of FW in a conventional FW technique.