Effect of Laying Hen's Age and Oviposition Time on Egg Cholesterol Content
Abdalla M. Abdalla 1*, Erneo B. Ochi 2
1 Department of Breeding and Reproduction Biotechnology, College of Animal Production, University of Bahri, Khartoum North, Sudan
2 Department of Animal Production, College of Natural Resources and Environmental Studies, University of Juba, Juba, South Sudan
The effect of the age and oviposition time on yolk cholesterol content and total yolk cholesterol was investigated in laying hens. Three hundred, twenty-two weeks old, ISA-Brown hens were raised in layer battery cages under the confined system for 16 weeks. Of which, oviposition time was recorded in the morning and afternoon egg collections. These egg samples were randomly collected nine times at a one-week interval based on hen's age. At each time, fifteen eggs laid in the morning and a similar number laid late in the afternoon were collected. Yolk samples were prepared followed by saponification and extraction of lipids. Yolk cholesterol content was determined using a spectrophotometer. Total yolk cholesterol was then calculated. The age of laying hens showed a significant effect; as the age progressed, yolk cholesterol content was decreased (14.44-14.32 mg/g yolk); whereas, total yolk cholesterol was increased (178.04-214.75 mg/egg). The oviposition time showed a significant effect as reflected by the lower yolk cholesterol content of morning eggs (12.53 mg/g yolk) compared to afternoon eggs (16.23 mg/g yolk). Furthermore, morning eggs had significantly lower total yolk cholesterol (176.63 mg/egg) than afternoon eggs (221.14 mg/egg). Hence, morning eggs are superior to meet the interest of table egg producers and consumer demand.