Effect of Age on the Performance of Laying Hens During the First Year of Production

Abstract Two hundred and seventy White Leghorn hens were used in this study. The experimental period commenced at 23 weeks of age and continued for 48 weeks. A daily light period of 14 hours was consistent for the whole experimental period. The individual hens were fed ad libitum with one of two isocaloric diets, containing 15 or 17% protein. Each feeding space provided the same level of environmental complexity and the feeder outline intentionally did not prevent visual contact across adjacent cages or cage rows and therefore, did not prevent the social facilitation of feeding responses. The effect of age during the laying season significantly influenced feed conversion, feed consumption and the weights of fresh and freeze dried egg components. Moisture contents of fresh yolk and fresh albumen did not exhibit parallel changes with age. Diets significantly affected egg production (73.2% vs. 71.9%), average daily egg mass production (46.65 g. vs. 46.30 g.), and the weight of freeze dried albumen (4.30 g. vs. 4.37 g.) for the 15 and 17% protein diets, respectively. The only significant interaction between diets and age were detected for egg mass. The distribution of individual feed conversion ratios and egg shell deformation deviated from normality both being positively skewed and kurtotic.