Use of the synthetic oxycarotenoids, β-apo-8′-carotenoic acid ethyl ester and citranaxanthin, in diets low in natural pigments to enhance egg yolk colour

Abstract

The effects of synthetic yellow and red oxycarotenoids, G-apo-8'-carotenoic acid ethyl ester (CAEE) and citranaxanthin (CTX), respectively, on egg yolk colour were evaluated in three experiments. In experiment 1,192 hens of two breeds (White Leghorn x Australorp and White Leghorn hybrid) were given a basal diet supplemented with CAEE in six concentrations from 1.75 to 3.00 mg/kg in the periods 35-38,47-50 and 59-62 weeks of age. Yolk colour (averaged over both breeds and all periods) increased linearly from 4.4 to 5.3 Roche units with CAEE concentration. The hybrids and crossbreds averaged 4.1 and 5.6 respectively. Although yolk colour was related to feed consumption, a difference of 17.7 g/bird.day between breeds accounted for only 0.2 of the 1.5 difference in yolk colour. Experiment 2 utilized the same birds as experiment 1. The same concentrations of CAEE were combined with 1.50 or 1.75 mg/kg CTX in the periods 39-42, 51-54 and 63-66 weeks of age. Yolk colour (averaged over all other effects) increased linearly from 8.7 to 9.1 with CAEE concentration. Yolk colour averages were 8.5 and 9.3 for CTX at 1.50 and 1.75 mg/kg respectively. In the third experiment, 180 White Leghorn x Australorp hens were given CAEE (1.50, 1.75 or 2.00mg/kg) and CTX(1.50, 1.75 or2.00mg/kg) from 18 to 62 weeks of age. Average yolk colour increased linearly from 10.0 to 10.3 with CAEE and from 9.9 to 10.4 with CTX, as the respective concentrations were increased.