|Nisbet, David - Dave|
Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/17/2004
Publication Date: 2/3/2005
Citation: Donalson, L.M., Kim, W.K., Woodward, C.L., Herrera, P., Kubena, L.F., Nisbet, D.J., Ricke, S.C. 2005. Utilizing different ratios of alfalfa and layer ration for molt induction and performance in commercial laying hens. Poultry Science. 84:362-369. Interpretive Summary: Egg laying chickens, like egg layers of many other bird species, undergo a natural process called molting, where feathers are lost, the reproductive tract shrinks, and the hens quit laying eggs; basically, the hens have a period of rest. This is followed by the growth of a new set of feathers, an increase in the size of the reproductive tract, and the beginning of a second cycle of egg production. In commercial egg production, the hens do not experience molting until the end of a long laying period when the number of eggs and the quality of the eggs decreases as the hens get older. Since it is often economically advantageous to add a second productive egg-laying cycle, producers often induce a molt. Feed withdrawal and a reduction in the length of time the hens receive light is the primary method used in the layer industry. This method has come under scrutiny because of food safety issues and animal welfare issues, causing much interest in developing molting methods other than feed withdrawal to achieve the same benefits without the increased food safety issues and be more acceptable, with respect to animal welfare. This study involved feeding alfalfa mixed with layer ration in different ratios (100% alfalfa [A100], 90% alfalfa and 10% layer ration [A90], and 70% alfalfa and 30% layer ration [A70] and a full fed non-molted control [FF], and feed withdrawal [FW] treatment for 9 days. Egg production ceased within 8 days and ovary and oviduct weights were reduced in all groups except the FF. The non molted hens (FF) and A70 treatment hens had lower egg production than the other treatments during the 39 weeks after molting. This research is important because, based on the results of this study, alfalfa or alfalfa mixed with layer ration appear to be methods that can be used to get a successful molt and good performance after the molt and be much more acceptable from an animal welfare standpoint.
Technical Abstract: Molting is a common practice used by the commercial egg industry to rejuvenate flocks for a second or third laying cycle. During this time the hens rest from production and the reproductive organs are rejuvenated in order to increase production and quality in the next laying cycle. While feed withdrawal is the most popular and effective method of molt induction, it has come under scrutiny due to food safety issues and animal welfare issues. This study involved feeding alfalfa mixed with layer ration at different ratios to hens to determine their ability to induce molt. The treatment ratios were 100% alfalfa (A100), 90% alfalfa/10% layer ration (A90) and 70% alfalfa/30% layer ration (A70). In addition, a full fed (FF) non-molted control and a feed withdrawal (FW) negative control were used. Alfalfa is an insoluble, high fiber feedstuff with low metabolizable energy. Egg production for A90 and feed withdrawal (FW) treatments ceased completely by day 6 while birds fed A100 and A70 ceased by day 8. Ovary and oviduct weight of hens fed all molting diets decreased significantly (P< 0.05), by an average of 1.5-2.5 % (body weight basis), compared to FF control during the 9-day molt induction period. As % layer ration increased, feed intake also increased and % body weight loss decreased during the 9-day molt induction period. Hens molted by FW lost an average of 25.8% body weight whereas A70 hens lost 18.9% body weight. Non molted hens (FF) and A70 treatment hens had significantly lower (P<0.05) egg production when compared to all other treatments over the 39 week post molt period. FF treatment hens also had significantly lower (P<0.05) albumen heights when compared to all other treatments. From these results, alfalfa or alfalfa mixed with layer ration appear to be viable alternatives to conventional feed withdrawal methods for the successful induction of molt and retention of post-molt performance.