Performance of laying hens as affected by split time and split composition dietary regiments using ground and unground cereals.

A factorial experiment was conducted to study the effects on the performance of White Leghorn X Australorp laying hens of diets based on unground cereal grains, small morning and large afternoon meals, and morning and afternoon meals of different composition. From 10 to 21 weeks of age the pullets' food intake was restricted, using either a diet in which the wheat fraction (600 g/kg) was unground or a fully ground diet of similar composition. In the laying period the birds received either a diet (U) in which the limestone was granulated and most of the cereal fraction (wheat and oats or wheat and sorghum) was unground or a fully ground diet (G) of similar composition. Both laying diets were offered ad libitum (A), with 25% issued in the morning and 75% in the late afternoon (T) or as a protein concentrate (250 g/kg of total diet) in the morning and cereal/limestone fraction (750 g/kg) in the late afternoon (C). Rearing and laying performance were unaffected by rearing diet. Laying diet U resulted in a 5.2% increase in food intake and a 0.9 g increase in average egg weight compared with diet G. From 21 to 56 weeks of age, when the cereal/limestone fraction of the diet included oats (240 g/kg of total diet), diet U resulted in fewer (4.8/bird) eggs and a lower financial margin than diet G. From 56 to 80 weeks of age, when oats were replaced by sorghum, this trend was reversed (-3.5 eggs). Birds on diet C produced fewer (16.9) eggs of lower (1.5 g) average weight than birds on diet A, ate less (1.39 kg) food and had a lower financial margin.(ABSTRACT TRUNCATED AT 250 WORDS)