|Lay, jr, Donald - Don|
Submitted to: International Society of Applied Ethology
Publication Type: Abstract only
Publication Acceptance Date: 6/4/2004
Publication Date: 6/18/2004
Citation: Koch, J.M., Lay, Jr., D.C., McMunn, K.A., Wilson, M.E. 2004. Alternative method to induce molt that addresses hen well-being [abstract]. International Society of Applied Ethology. Interpretive Summary:
Technical Abstract: Molting of hens increases egg quality and production, extending the productive life of hens. The method used to molt hens has received public criticism regarding hen well-being. Traditional molting is done by withdrawing feed and decreasing light, which leads to weight loss and increased mortality. Alternative methods (feeding low nutrient density feeds or diets low in calcium or zinc), have resulted in poor post-molt performance and increased tissue damage in the hen. An alternative that results in improved post molt performance, addresses hen well-being and is economical for producers is desired by the poultry industry. Feeding a progestin should increase hypothalamic negative feedback, decreasing support for the ovary and a subsequent loss of steroidogenic support for the oviduct and cessation of lay. We have demonstrated that incorporating melengestrol acetate (MGA), an orally active progestin, in a balanced layer diet induces molting. Hyline W-36 hens (n=48) were randomly assigned to one of three treatments for nine days. Hens were fed either a balanced layer diet containing 7.27% propylene glycol (control), the same diet containing 8 mg/day MGA in propylene glycol (MGA) or received no feed (restricted). Three weeks prior to starting the experiment hens were trained to peck a disk in order to receive a feed reward based on a progressive ratio reinforcement schedule. Hens that were not successfully trained were excluded from the experiment. Motivation of hens to acquire feed was tested for 15 minutes on days 0, 3, 6 and 9. The total number of pecks (pecks) and total number of feed rewards (rewards) per bird were recorded. There was no increase in pecks or rewards in either control or MGA hens from day 0 to 9 (47.2 ± 8.6 and 6.8 ± 0.9). However, by day 9 there was marked increase (p < 0.05) for restricted hens in pecks (d0 33.1 ± 6.4 vs. 141.5 ± 56.0) and rewards (6.5 ± 0.9 vs. 14.2 ± 3.5). Hens that are molted by feeding MGA are not more motivated to acquire feed than control hens, and less motivated than hens on a restricted diet. Therefore feeding MGA is an effective method to induce molt that also addresses the well-being of the hen.