Yolk colour carotenoid and retinol level in the eggs of rural, urban range reared and cage reared chicken in two seasons

A factorial experiment of three rearing systems into two seasons was conducted using eggs from range birds of rural and urban areas and commercial chicken eggs from cage layers. The eggs from rural poultry were collected from villages spread throughout Tamilnadu and urban eggs from ten places around Chennai city, the commercial eggs were taken from ten wholesale outlets located in the city of Chennai. 300 eggs each for rural, urban and commercial eggs respectively were collected each season monsoon and summer, comprising of a sum of 900 eggs during each season. 90 eggs were randomly selected from these 900 eggs each season (30 eggs for each rearing system) and yolk colour, carotenoid and retinol levels were estimated in these eggs. There was a highly significant (P<0.01) difference in the total carotenoid content between the different rearing systems and seasons. Eggs collected from the rural birds gave significantly (P<0.01) higher total carotenoids when compared to the urban range reared or the commercial layer eggs. Eggs laid during monsoon season had significantly (P<0.01) higher total carotenoids. Retinol levels also showed a highly significant (P<0.01) difference between rearing systems and seasons. Eggs from the commercial layer and eggs collected during the monsoon season had significantly (P<0.01) higher retinol levels.