Effect of split feeding on performance and egg quality of aged laying hens

Laying hens are kept in production on average until 80 wk of age. However, it is predicted that by 2020 genetic selection will make it possible to keep hens until 100 wk of age and produce 500 eggs per housed hen (Van Sambeek, 2010). One of the most important concerns however, is to maintain egg quality in longer production periods. In fact, not only genetic selection but also optimization of feeding systems is necessary to reach the goal of a 100 wk long production cycle. One of the possibilities is to apply an alternative feeding concept, the so called split feeding. This system is based on the varying nutrient requirements and calcium (Ca) utilization of hens during the day. In the first half of the day, after ovulation and during albumen formation hens need an energy- and protein rich diet, whereas during the afternoon and evening, when shell formation occurs, a diet with a higher Ca content is needed. However, not only the Ca content but also its form is important in the feed. Limestone (LS) is widely used as a Ca supplement in fine- (F) as well as coarse (C) form. It has been reported that C-LS particles (>0.8 mm) solubilize more slowly in the gizzard and intestine, allowing a more gradual Ca release to the plasma pool. In contrast, F-LS due to its powdery form is immediately available for absorption (Zhang & Coon, 1997).These properties make F-LS an ideal supplement during the first half of the day when medullary bone formation occurs and no eggshell is being formed. C-LS can be fed during the afternoon to supply Ca for the night when only the crop’s content and the medullary bone reserves can support shell formation. Therefore, the aim of this experiment is to investigate the effect of split feeding treatments on performance and egg quality of aged laying hens (75-90 wk of age).