成都地区饲养伊莎褐商品蛋鸡的开产日龄与早期生产性能的观察

The Observing Experiment of Commercial ISA Brown's Age of First Egg and Prducing Performance of Early period

对２３６００多只伊莎褐商品蛋鸡在成都地区饲养条件下，开产日龄的分布和早期生产性能的观察中，以及在本群鸡只在根据不同的开产日龄设置四个试验组的小群观察试验中发现，该品种鸡只的开产日龄和产蛋率达５％、５０％和９０％以上的产蛋日龄，均比该品种计划目标提前１～２周，开产期长达３８天左右，欠整齐统一；四个试验组的开产日龄均与开产体重相关，其体重均要达到该品种２０周龄的体重标准（１５５０～１６５０ｇ）上下限±５％时鸡只才开产，晚开产鸡只是固体重过重或过轻，这是群体开产日龄不整齐规格的主要原因；开产早的１、２组的产蛋至多，平均产蛋率高于３、４组，差异极显著（Ｐ＜０．０１），３和４组平均蛋重大于１、２组，差异极显著，（Ｐ＜０．０１），但在同期水平上，各组间平均蛋重差异不显著，随日龄的增长，各组间蛋重差异越来越小；在前期产蛋中各组所创总产值和只平产值，仍是１组＞２组＞３组＞４组，说明了达到该品种开产体重标准的鸡只，提前开产能获得较好的产蛋效益。

In the feeding conditions of chengdu area,the ranae of first -egg age and producingperformance of over 2 3,600 commercial LSA Brown layers were observed. Four small groups werebuilt according to different first-egg age in this flock.It was found that the time of first egg and 5%,50%and above 90%laying rates was 1～2weeks earlier than the plan objective. The period ofbeginning-laying lasted about 3 8 days which lacked concurrence. The first- egg age and theyweightwere correlated in the four groups. All hens began to lay only when their bodyweight reached the 2 0～week standard(1550～1650g)of the breed.The todyweight of the delaying group was too heavy ortwo light and it is the main reason of the long lastation of first-egg ages. Egg production of group l and2 were more and the laying rates were significantly higher than those of group 3 and 4(P<0. 01).Theaverage egg weight of group 3 and 4 was significantly higher than group 1 and 2(P<0.01).But thedifference among different groups was not significant at the same period,The difference of egg weightamong different groups decreased with the age increasing.The whole and average incomes of differentgroups in early peried were still 1>2>3>4.The results suggested that better economic incomes couldbe preduced by the early-beginning laying hens when the layers reached the bodyweight standard of the breed.