The Effects of Strain and Cage Shape and Density on Performance and Fearfulness of White Leghorn Layers

Abstract

Two strains of White Leghorn pullets were tested for production performance and fearfulness for population sizes of 4 and 5 birds in deep and shallow design cages. The deep cage measured 38.1 cm across the front and 50.8 cm in depth while the shallow cage measured 60.9 cm across the front and 31.8 cm from front to back. Significant strain differences were observed for egg production, feed usage, feed conversion, egg size, and egg grades. Birds in shallow cages had higher egg production rates, greater body weight gains, used more total feed, and produced greater egg mass and more large-plus size eggs than birds in the deep cages. Increasing bird density resulted in reduced egg production, increased mortality, reduced body weight gains, and reduced feed usage and feed conversion figures. Egg mass and percentage large-plus eggs were also reduced with increased density while percentage undergrade eggs increased. Egg incomes over pullet and feed cost were not statistically significant. However, strain effects for egg income were greater than cage shape or density effects. Average net incomes favored the shallow cage and the higher bird density. Significant strain by density interactions were present for feed usage and net egg income while cage by density interactions occurred for feed usage and feed conversion figures. No differences for “fearfulness” were observed.