EGG CHARACTERISTICS OF HIGH-PERFORMANCE HENS AT THE END OF LAY WHEN GIVEN CAFETERIA ACCESS TO ENERGY, PROTEIN, AND CALCIUM

Hens in excess of 90% egg production were selected from a flock at 67 weeks of age. All birds fed a complete mash (18% protein, 2800 kcal metabolizable energy (ME)/kg, 3.75% Ca) for a 4-week standardization period. Two groups of 15 birds each were formed on the basis of equivalent production, egg weights, and body weights. One group continued to receive the complete feed for a subsequent 4-week experimental period while the other group had free choice of a high energy mash (8% protein, 2800 kcal ME/kg 0.75% Ca), a 50% protein pellet (2500 kcal ME/kg, 0.20% Ca), and oyster shell flakes. During the last week of each period, consumptions were determined at 2-hr intervals and eggs evaluated for quality, yield of physical components, and albumen electrophoretic distribution. No differences in production or in egg and body weights occurred because of feeding regimen. Hens, receiving the complete mash feed, consumed more ME, protein, and calcium on egg-layering days, but they utilized proportionately less of each than if these nutrients were cafeteria fed. Cafeteria access led to the consumption of protein early in the day while calcium was consumed later. Resultant eggs had an improved shell strength and an increased inner thin albumen at the expense of thick albumen. Protein concentration of outer thin, thick and inner albumens remained constant, but constituent ovalbumin A1 increased while conalbumin, ovalbumins A2, and A3 decreased. Given the opportunity, hens consume nutrients parallel to their needs for egg formation, and in turn, improve shell and albumen.