The deposition of carotenoids and α-tocopherol in hen eggs produced under a combination of sequential feeding and grazing

Abstract

This experiment was conducted to determine how layer performance and the concentrations of lutein, zeaxanthin, α-tocopherol and β-carotene in the egg yolks of grazing hens would be influenced by sequential feeding of whole wheat and balancer mixed feed. One hundred twenty free-range hens, divided into two groups, were used in the experiment. The experimental treatment group of 60 hens had access to permanent grassland, whereas the control group only had access to a range without grass. The feed dosages were determined according to the metabolisable energy (ME) requirements, calculated based on body weight, the performance of the hens and the air temperature. Compared with the control group, the grazing hens received a 9% lower dose of ME, which included wheat and balancer diet, to ensure pasture intake. Lyophilised permanent pasture contained 128mg/kg dry matter (DM) of lutein, 115mg/kg DM of zeaxanthin, 75mg/kg DM of α-tocopherol and 79mg/kg DM of β-carotene. Grazing by hens, together with sequential feeding of whole wheat and a balancer mixed diet, significantly increased (P<0.001) the egg concentrations of lutein (by 260μg), zeaxanthin (by 174μg), α-tocopherol (by 270μg) and β-carotene (by 2μg) relative to the control group. The colour of the egg yolks of the grazing hens was assigned a Roche Yolk Colour Fan score of 10.3. Grazing, together with sequential feeding, resulted in the production of eggs with increased oxidative stability measured after storage at 18°C for 28 days. This feeding system permitted the production of eggs as functional foods with significantly increased concentrations of carotenoids without compromising the performance of the hens.