Effects of Age of Laying Hens on Internal and External Quality of Eggs
2018
Kim, D.J., Korea Institute for Animal Products Quality Evaluation, Sejong, Republic of Korea | Kim, D.H., Konkuk University, Seoul, Republic of Korea | Kang, S.J., Korea Institute for Animal Products Quality Evaluation, Sejong, Republic of Korea | Kwon, K.M., Korea Institute for Animal Products Quality Evaluation, Sejong, Republic of Korea | Lee, J.C., Korea Institute for Animal Products Quality Evaluation, Sejong, Republic of Korea | Lee, K.W., Konkuk University, Seoul, Republic of Korea
This study was conducted to evaluate the effect of age of laying hens on egg internal and external qualities. A total of 8,300 eggs were randomly collected from 15 grading & packaging (GP) centers, and 50 eggs per farm during April to May in 2015. Age of laying hens ranged from 18 to 65 weeks of age and they were classified into 5 age groups (18~25, 26~35, 36~45, 46~55, and 56~65 weeks). Egg weight increased, but the Haugh unit decreased as the age of laying hens increased. Yolk color was higher in eggs laid from 25∼35 weeks of laying hens compared with that of 18∼25-weeks-old chickens. The incidence of dirty eggs was highest (P less than 0.05) in 18∼25 week group and remained constant after 26 weeks. Among eggshell defects, speckled and pimpled eggs increased as the age of laying hens increased. The incidence of calcium deposits and misshapen eggs was highest during 18∼25 weeks of age and remained constant after 26 weeks. The percentage of total eggshell cracks increased as the age of laying hens increased. Among eggshell cracks, star- and hair-like cracks were frequently noted. The percentage of meat spot was higher than that of blood spot and their incidence was highest among the 56~65 week group. Age of laying hens significantly increased egg weight, incidence of pimpled or speckled eggs, star- or hair-like cracks, and meat spot. On the other hand, a significant negative interaction between age of laying hens and the Haugh unit was noted. In conclusion, our study revealed that the age of laying hens affected internal and external egg qualities.
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