The effect of spectacles, a whole grain diet and dietary level of citranaxanthin on egg yolk colour, nesting behaviour and laying performance of crossbred hens

Abstract

In a 2 x 2 x 2 factorial experiment, the laying performance of 800 crossbred hens with or without spectacles and fed either whole wheat plus concentrate or a conventional mash diet supplemented with one of two levels of citranaxanthin was measured. Hens fitted with spectacles ate 9 per cent less feed, converted feed more efficiently, were better feathered and had lower daily intakes of protein, metabolizable energy, calcium and phosphorus than those without spectacles. Their rate of egg production was similar to that of hens without spectacles but egg weight was reduced and consequently these eggs had higher Haugh unit scores. They also tended to lay more eggs on the floor but the height of nests did not seem to influence their choice of nests. The dry weight of their skin plus feathers was 10.5 per cent lighter than that of the hens without spectacles. Hens fed whole wheat plus concentrate on a free choice basis ate 13.5 per cent less feed with no reduction in rate of lay or egg size, converted feed more efficiently, gained more liveweight, consumed less protein, energy, calcium and phosphorus per day than those given the mash diet. These hens showed a marked preference for nests at the lower level and tended to lay eggs with lower yolk colour scores. A 21 per cent reduction in feed intake was achieved when the two techniques of fitting spectacles and feeding whole wheat plus concentrate were combined. In diets containing natural xanthophylls, citranaxanthin at inclusion levels of 1.5 and 6.0 p.p.m. in mash and concentrate diets respectively, produced eggs with acceptable yolk colours.