February 7, 2010
Fasting—Stress induced by fasting during molting programs leads to elevated concentrations of circulatory adrenal corticoids, which may cause an impaired immune response.3 In addition, feed withdrawal during an induced molt is detrimental to the skeletal integrity of hens.4 Research has shown that fasting is not necessary to induce a molt in laying hens.
There are many effective non-fast methods that can be used to induce a molt including, but not limited to, feeding of low-sodium5, high-zinc5, high-corn5, high-wheat5, oral thyroxine6, ad libitum alfalfa7 and low-calorie1 diets. Also, molting induced by feeding a non-fasting diet of wheat middlings and corn has been shown to be less deleterious to bone mineralization as compared to a fast-induced molt.8
Behavioral patterns of hens in various molting programs have been examined by Dunkley et al. Nonnutritive pecking behavior is characteristically associated with hens undergoing feed withdrawal.9 The researchers found that hens subjected to feed withdrawal displayed nearly twice as much nonnutritive pecking when compared to hens fed a diet of alfalfa combined with a layer ration or fully fed hens.9 Another study revealed that hens subjected to a fast-induced molt exhibited more cage pecking during the molting stage than prior to molting and that hens undergoing both fast- and non-fast induced molts were more aggressive with other cage mates during the molting stage than during the premolt stage.1 Results of vocalization studies further support that frustration is associated more with food deprivation than with low-calorie diets.1 A higher gakel-calling rate and changes in vocal acoustic structure were observed in hens subjected to a fast-induced molt, but not in hens subjected to a nonfast-induced molt or that were not molted.1
Water deprivation—Water deprivation results in higher mortality and morbidity during the early stages of the molt cycle.5 Water deprivation is not necessary to achieve a molt in poultry and is inhumane. Light conditioning prior to induction of a molt has been shown to eliminate the need to restrict water to effect cessation of lay.5
Special attention should be paid to flock health, mortality, and bird weight when molts are induced. The welfare of birds should be a major consideration in this and any management practice. The AVMA encourages ongoing research into the effect of various methods of inducing a molt on the well being and performance of laying chickens.
REFERENCES1 McCowan B, Schrader J, DiLorenzo AM, Cordona C and Klingborg D. Effects of Induced molting on the well-being of egg-laying hens. J App Anim Welfare Sci. 2006;9(1):9-23.2 Berry WD. The physiology of induced molting. Poult Sci. 2003;82:971-980.3 Sandhu MA, Rahman ZU, Rahman SU and Hassan IJ. Dynamics of innate immune response in Gallus doesticus using two methods of induced molting. Vet Immuno Immpath. 2007;120:106-114.4 Mazzuco H and Hester PY. The effect of an induced molt and a second cycle of lay on skeletal integrity of white leghorns. Poult Sci. 2005;84:771-781.5 Biggs PE, Persia ME, Koelkebeck KW and Parsons CM. Further evaluation of nonfeed removal methods for molting programs. Poult Sci. 2004;83:745-752.6 Bass PD, Hooge DM, and Koutsos EA. Dietary thyroxine induces molt in chickens (Gallus gallus domesticus). Comp Biochem Phys. 2007;146:335-441.7 Landers KL, Woodward CL, Li X, Kubena LF, Nisbet DJ and Ricke SC. Alfalfa as a single dietary source for molt induction in laying hens. Bio Tech. 2005;96:565-570.8 Mazzuco H and Hester PY. The effect of an induced molt using a nonfasting program on bone mineralization of white leghorns. Poult Sci. 2005;84:1483-1490.9 Dunkley CS, Friend TH, McReynolds JL, Woodward CL, Kim WK, Dunkley KD, Kubena LF, Nisbet DJ and Ricke SC. Behavioral responses of laying hens to different alfalfa-layer ration combinations fed during molting. Poult Sci. 2008;87:1005-1011.