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Nutrient Modelling for Laying Hens

Department of Animal Science, University of Minnesota, St. Paul, MN 55108; Phone: (612) 624-6263; FAX: (612) 625-5789

Correspondence: Craig N. Coon

Modelling for laying hens is more complex than for meat-producing poultry. Layers need to partition daily nutrients into maintenance, weight gain, and egg mass production. Partitioning models such as the Reading and Israeli models are presently used to determine amino acid requirements for layers, but the development of mechanistic models should be the future direction of modelling. Based on the premise that layers attempt to consume their daily dietary energy needs, the ability to predict daily ME intake accurately is limited because there is a lack of good research about utilization of dietary ME for maintenance, tissue, and egg synthesis. Model users should be aware of the restricted range of conditions for which a model is applicable. Substantial differences about the predicted requirements of dietary ME and amino acids for laying hens occur in the literature. Quantitative studies on the factors that influence egg production (hence profitability of an enterprise) such as genotypes, diet composition, availability of nutrients for metabolism, environmental conditions, animal disease status, as well as the interactions among the factors are needed for future development and application of models.

Key Words: Amino acids • laying hens • metabolizable energy • modelling • prediction