A comparative study on pause and clutch size traits in relation to egg production traits in three local breeds of chickens [electronic resouce].

Includes references.

The records of 305 Dandarawi (Dand), 303 Fayoumi (Fay) and 452 Golden Montazah (GM) hens from Fayoum Poultry Research Station were used in this study. Four measurements for clutch and pausing traits were calculated for each hen within the studied breeds. These traits were: the average clutch size (number of eggs per clutch of each hen, CS90), the number of clutches (CN90), the average length of pause duration (PD90) and the occurrence number of pauses (PN90). GM had significantly (P≤0.01) higher CS90 mean and standard error (3.69 and 0.22) than other breeds whereas Fay showed significantly (P≤0.01) higher CN90, PD90 and PN90 (22.63, 2.24 and 22.9, respectively). Egg number, egg mass in the first 90 days of production and PD90 for all breeds showed considerable maternal effects. However, higher estimates for h2 S than those calculated from the dam components indicated existence of sex-linked effects on CS90 for the three breeds studied and CN90 and PN90 for Dandarawi and Golden Montazah breeds. Phenotypic and genetic correlations between pause and clutch size traits and with some egg production traits for the breeds studied were also calculated. Individual selection for improving CS90, CN90, PN90 and PD90 traits would be more useful for Golden Montazah. It can be concluded that, GM had a good merit of the egg production performance than other breeds. Expected genetic response for GM to individual selection was estimated to be 3.76, 9.65, 10.27 and –1.21 for the four traits, respectively. For selecting both Dand and Fay females for either CS90 or CN90, family selection based on full sib showed better efficiency compared to individual selection when family size was six hens. Family selection based on full sib showed better efficiency than on half sib. However, for selecting males, sib selection based on full sib showed better efficiency when family size was at least eight hens. It can be seen that the bigger the family size, the better the efficiency was. The expected reduction in PD90 after one generation of individual selection for either GM or Dand had a considerable reduction in pause length. Moreover, the lower value for CS90 recorded for Fay (1.84 egg) and a relative longer PD90 (2.24 days) and a lower h2 than both GM and Dand suggested the need for selection to increase its CS90. Family selection reduced PD90 and increased clutch traits for Fay and it would be useful for improving egg production in the first 90 days. However, individual selection for improving these traits would be more useful for GM and Dand. A selection index including clutch, pausing traits and a full record of egg production is suggested.

Summary in Arabic.

1