Effect of Age of Laying Hens and Grade of Egg Shell Abnormality on Internal Egg Quality
2012
Kim, H.S., Korea Institute for Animal Products Quality Evaluation, Gunpo, Republic of Korea | Kim, S.M., Korea Institute for Animal Products Quality Evaluation, Gunpo, Republic of Korea | Noh, J.J., Korea Institute for Animal Products Quality Evaluation, Gunpo, Republic of Korea | Lee, J.I., Korea Institute for Animal Products Quality Evaluation, Gunpo, Republic of Korea | Lee, H.J., Chungnam National University, Daejeon, Republic of Korea | Jo, C.U., Chungnam National University, Daejeon, Republic of Korea
This study was carried out to investigate the effects of age of laying hens and grade of shell abnormality on internal egg quality. At each week, 1,000 eggs were randomly selected from 21,000 eggs laid by Hy-Line hens (100,000 birds) aged from 56 to 62 wk. The samples were divided into normal and externally abnormal eggs by an official egg grader. Then, egg quality including egg weight, egg white height, Haugh unit and yolk color was evaluated from each normal and abnormal eggs. The production rate of externally normal and abnormal eggs was 81.22 and 18.78%, respectively. No difference found in the production rate by the increase of hen's age, but Haugh unit of eggs from hens of 60-wk-old was higher (p less than 0.05) than that of 56-wk-old. When the same age groups were compared, egg white height and Haugh unit were lower in eggs which were externally abnormal. When the grade of abnormality increased, egg white height and Haugh unit were decreased further (p less than 0.05). Among the externally abnormal eggs, malformation showed the lowest Haugh unit. In conclusion, the shell abnormality of eggs laid by hens aged 56 to 62 wk was closely related with internal egg quality. Therefore, the grading external egg quality in the present egg grading system is directly related with the internal egg freshness.
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