The authors summarize the magnitude and nature of the improvement of production traits in layers and broilers based on the results of international strain comparisons conducted in Hungary and other European countries. Layer hibrids showed an annual improvement exceeding 2 eggs/hen in the last two decades. Brown egg layers improved more rapidly in feed efficiency compared to leghorns (-0,6 kg feed/egg kg for the browns, -0,5 kg/egg kg for leghorns), mainly due to improved egg production and reduced body weight. Today layers start to lay 15-20 days earlier than 20 years ago. Weight gain of broilers improved by 30% for males, and 40% in females in the last 20 years comparing both the best individual and pen mean performances (49 day body weight). As a correlated response, broiler males reach 6 kg live weight 7 weeks earlier compared to broilers of the 1980s, in females the difference is even greater. In layer type hens selection for egg production traits did not lead to negatively correlated responses regarding vitality related characteristics. Selection for improved growth rate in broiler populations resulted in a decreased adaptiveness to various unfavourable environmental conditions.
|Translated title of the contribution||The magnitude and nature of changes in performance of the chicken|
|Number of pages||6|
|Journal||Magyar Allatorvosok Lapja|
|Publication status||Published - Dec 1 2000|
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