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Response to Varying Dietary Energy and Protein With or Without Enzyme Supplementation on Leghorn Performance and Economics. 2. Laying Period

C. L. Novak^*,1,2, H. M. Yakout and J. Remus

^* Department of Animal and Poultry Science, Virginia Tech, Blacksburg 24061; Poultry Production Department, Alexandria University, El-Shatby 21545, Alexandria, Egypt; and Danisco Animal Nutrition 411 East Gano, St. Louis, MO 63147

Correspondence: ¹ Corresponding author: CLNovak{at}landolakes.com

Commercial laying hens were used to evaluate the use of an enzyme cocktail during their first cycle of lay. Hens were fed 1 of 8 dietary treatments that varied in ME and dietary protein, with or without exogenous enzymes, at an inclusion rate of 0.0375%, from 18 to 60 wk of age. Reducing dietary protein lowered BW gain, egg weight, and egg mass and impaired FCR. In addition, the albumen percentage decreased, whereas the yolk percentage and color increased when feeding lower protein diets. Percentage of energy and protein retention was generally increased by reducing dietary protein. Feeding hens less protein reduced protein digestibility at 60 wk. Dietary ME had little effect on most hen performance parameters. Although reducing ME increased redness of the egg yolk, absolute energy retention was lower when reducing ME overall. Energy digestibility at 60 wk was lower when ME was reduced. Enzyme supplementation reduced egg weight and increased yolk redness during phase A, and reduced egg mass and impaired FCR during phase B. Enzyme supplementation had little effect on energy and protein retention, whereas the response on excreta nitrogen was inconsistent. Excreta nitrogen was lower when feeding hens less protein, thus having a positive impact on the environment. Feeding diets lower in dietary protein or ME reduced the cost of feed, whereas enzyme supplementation increased the overall cost to produce a pound of egg.

Key Words: metabolizable energy • dietary protein • enzyme supplementation • laying hen

² Current address: Commercial Poultry Nutrition, Land O’Lakes Purina Feed, LLC, 12200 N Ambassador Dr., Suite 225, Kansas City, MO 64163.