Hulya Atil

A Comparison of Different Selection Indices for Genetic Improvement of Some Dairy Milk Traits in Holstein Friesian Cows in Turkey

Abstract Atil, H., Khattab, A.S. and Gevrekci, Y. 2005. A comparison of different selection indices for genetic improvement of some dairy milk traits in Holstein Friesian cows in Turkey. J. Appl. Anim. Res., 27: 117–120. A total of 1680 first lactation records of Holstein Friesian cows sired by 206 bulls maintained at five herds in Turkey were used to estimate phenotypic and genetic parameters for 305 day milk yield (305 dMY), lactation period (LP) and age at first calving (AFC). Data were analysed using Multiple Trait Derivative Free Restricted Maximum Likelihood (MTDFREML). The model included the fixed effects of herd, season and year of calving and parity, AFC as a covariate and individual and residual as random effects. Genetic correlations between 305 dMY and AFC; and LP and AFC were 0.90 and −0.95, respectively. Phenotypic correlations among all traits studied were generally similar to the corresponding genetic correlations. Index I1 incorporating 305 dMY, LP and AFC was the best (RIH=0.75). It is recommended that selection should be exercised at the end of the first lactation.

Yumurta Verimi Üzerine Bazı Özelliklerin Etkisinin Regresyon Ağacı Analizi ile Belirlenmesi

Karar agaclari veri madenciliginde siniflandirma ve tahminleme yapmak amaciyla yaygin olarak kullanilan bir yontemdir. Regresyon agaci teknigi ise bagimsiz degiskenlerin birbirleri ve bagimli degiskenle aralarindaki iliskileri inceleyen ve sonuclari agac seklinde bir diyagram ile ozetleyen bir karar agaci algoritmasidir. Bu arastirmada yumurta verimi (adet) uzerine kafes, kulucka donemi, sira, eseysel olgunluk yasi ve eseysel olgunluk agirligi ozelliklerinin etkisi siniflandirma ve regresyon agaci analizi ile incelenmistir. Turkiye’de yetistirilen bir yumurtaci suruden toplam 1980 adet yumurtacinin verimleri ve soz konusu ozelliklere iliskin katsayilar calismada kullanilmistir. Regresyon agaci analizi sonucunda yumurta verimi uzerine eseysel olgunluk yasinin en etkili oldugu, bunu kulucka donemi etkisinin izledigi gozlenmistir. Yumurta verimi ortalamasi eseysel olgunluk yasi 172.5 gunden kucuk veya esit olan yumurtacilarda 105.805 ± 0.29 iken, 172.5 gunden buyuk olanlarda bu deger 73.848 ± 2.47 olarak belirlenmistir.1. ve 2. kulucka donemindeki yumurtacilarin yumurta verimi ortalamasi 107.33 ± 0.28iken, 3. ve 4. kulucka donemindeki yumurtacilar icin bu deger 93.83 ± 1.04 olarak bulunmustur.