The effect of rice pollard and manganese levels in the diet on egg weight, shell quality and performance of crossbred layers

In two 2×4 factorial experiments the laying performance of 768 White Leghorn×Australorp hens given diets based on either meat and bone meal (MBM) or soya bean meal (SBM) as the principal protein supplements, each supplemented with either four levels (0, 80, 160 and 240 g kg −1 ) of rice pollard or four levels (85–74; 93–105; 113–122 and 136–141 mg kg −1 ) of manganese, was measured. In both experiments, the hens given the SBM diets laid heavier eggs with lower yolk colour than those given the MBM diets. The inclusion of 80 g kg −1 or more of rice pollard in either MBM or SBM diets increased egg weight and the percentage of 65 g and 60 g grade eggs. The egg weight response to diets with 160 and 240 g kg −1 rice pollard was not greater than that for diets with 80 g kg −1 rice pollard. Rate of lay was reduced and body weight increased on diets with 80 and 160 g kg −1 rice pollard but not on the diet with 240 g kg −1 rice pollard. Feed conversion efficiency was higher on the diets with 160 and 240 g kg −1 rice pollard than on the other diets. Rice pollard reduced yolk colour on MBM diets. The specific gravity of eggs on the diets with rice pollard was higher than on the control diets. Increasing the dietary level of rice pollard increased the concentration of linoleic and arachidonic acids and reduced that of palmitic, palmitoleic and oleic acids in egg yolk lipids. Increasing levels (74 to 141 mg kg −1 ) of manganese in the diet had no significant effect on either egg production or egg shell quality characteristics.