Freeman, 2009 – Alternative methods for disposal of spent laying hens: Evaluation of the efficacy of grinding, mechanical deboning, and of keratinase in the rendering process

Like many industries today, the poultry industry faces the challenge of producing high quality products in a manner which meets consumer expectations, satisfies environmental regulations, and that maximizes profitability. In the process of meeting these demands, it is estimated that over 144 million live, spent layers must be removed annually from production (C.A.S.T., 1995; Lyons and Vandepopulier, 1996). The yield of white meat per spent hen is only 166 g, which yields a value to processors that barely covers the cost of handling the birds (Middleton, 2000). Because the cost of removing spent laying hens from the farm often exceeds their value for meat (Aho, 1999), euthanasia followed by burial, composting, or incineration are often used for depopulating hen houses. These methods raise environmental concerns. Finding methods of disposal that minimize nutrient and biohazard emissions into the environment while yielding residual value to the poultry producer is a great challenge. Converting proteinaceous animal wastes, such as spent hens, into feedstuffs is one of the most biologically efficient means for recycling nutrients. The objective of this project was to investigate the potential of adding value to spent fowl as a raw material for protein byproduct meals by using novel applications of available technologies. The efficiency and feasibility of grinding, mechanical picking, and mechanical separation of meat (mechanically deboned meat, MDM, consists primarily of meat, skin, and viscera) from hard tissue (feathers and bones) were measured and the nutritive value of the various end products determined. The impact of keratinase hydrolysis on the availability of protein in the hard tissues was also evaluated.