Position

The Canadian Veterinary Medical Association (CVMA) is opposed to moult induction by methods involving deprivation of food or water, or by other methods that subject birds to undue or added stress.

Background

In commercial production, forced moulting typically involves some combination of restricting daily energy intake and modification of light exposure that causes regression and regeneration of the reproductive tract in late-cycle egg laying chickens, and in poultry breeding flocks.  This is accompanied by marked feather loss and replacement.  An average 30% weight loss per hen and 1.2% mortality follows the above-noted feed withdrawal (1,2).  On completion of forced moulting, subsequent egg production levels approach, but do not equal, that of young hens.  During renewed laying post-moult, eggs are larger in size and shell quality if improved compared to the flocks production pre-moult.

Although forced moulting provides some animal welfare benefits in terms of decreased overall numbers of animals utilized, techniques that involve feed or water deprivation adversely affects the well-being of laying hens (3) and increase the shedding of some Salmonella spp (4).  Methods to decrease the associated stress while retaining the desired reproductive tract involution is an area of active research (5-8).

The use of forced moulting is rare in Canada.  Poultry producers in Canada do not support forced moulting by feed or water withdrawal (9).

References:

1. BELL, D.D. «Historical and current molting practices in the U.S. table egg industry», Poultry Sci, 2003, vol. 82, p. 965-970.

2. BERRY, W.D. «The physiology of induced molting», Poultry Sci, 2003, vol. 82, p. 971-980.

3. MCCOWAN, B., J. SCHRADER, A.M. DILORENZO, C. CARDONA et D. KLINGBORG. «Effects of induced molting on the well-being of egg-laying hens», J Appl Anim Wel Sci, 2006, vol. 9, n^o 1, p. 9-23.

4. GOLDEN, N.J., H.H. MARKS, M.E. COLEMAN, C.M. SCHROEDER, N.E. BAUER et W.D. SCHLOSSER. «Review of induced molting by feed removal and contamination of eggs with Salmonella enterica serovar Enteritidis», Vet Micro, 2008, vol. 131, p. 215-228.

5. KOELKEBECK, K.W. et K.E. ANDERSON. «Molting Layers - alternative methods and their effectiveness», Poult Sci, 2007, vol. 86, p. 1260-1264.

6. KOCH, J.M., D.C. LAY JR., K.A. MCMUNN, J.S. MORITZ et M.E. WILSON. «Motivation of hens to obtain feed during a molt induced by either feed withdrawal, wheat middlings or melegestrol acetate», Poult. Sci, 2007, vol. 86, p. 614-620

7.  KOCH, J.M., J.S. MORTIZ, D.C. LAY JR. et M.E. WILSON. «Effects of melengestrol acetate as an alternative to induce molting in hens and on the expression of yolk proteins and turnover of oviductal epithelium», Anim Repro Sci, vol. 102, 2007, p. 14-23.

8. GULDE, V.A.L., R. RENEMA et G.Y. BÉDÉCARRATS. «Use of dietary thyroxin as an alternate molting procedure in turkey breeder hens», 2008, Poultry Science Association Annual Meeting, p.37-38 (résumé).

9. AGRICULTURE ET AGROALIMENTAIRE CANADA. Code de pratiques recommandées pour le soin et la manipulation des animaux de ferme : Poulets, dindons et reproducteurs du couvoir à l’abattage, 2003. Disponible auprès des Producteurs de poulet du Canada. 1007-350, rue Sparks, Ottawa (Ontario) K1R 7S8.

(Revised June 2009 )