Effects of some factors on milk yield and components of Holstein-Friesian cattle in England.

ABSTRACT This study was conducted to determine the duration of lactation, lactation and 305 days milk yield, milk fat and protein percentage and somatic cell counts of Holstein-Friesian cattle selected randomly in five private farms in England and to investigate the effects of some environmental factors on these traits. Material of the study was 2514 yield records collected from Holstein-Friesian cattle between the years 1994 and 2003. In the statistical analysis of the yields, contrast-test of the GLM procedure in SAS programme package was used. General average of the duration of lactation, lactation and 305 days milk yield, milk fat and protein percentage and milk somatic cell counts were 324.32 days, 7715.23 kg, 7218.62 kg, 4.028%, 3.333% and 137,948 cell/ml respectively. During the study, the farm where the animals were kept and the year in which lactation started made significant effects at P<0.001 level on all traits, also the turn of lactation has made a P<0.05 level effect on these traits except the P<0.05 level effect on the duration of lactation. Season had no important effect on lactation milk yield and somatic cell count in milk. However, season, like other factors made significant effects on the duration of lactation, milk fat and protein rates at a level of P<0.001 and on 305 days milk yield at a level P<0.01. The results of this study showed that the farms achieved high levels of milk yield by providing optimal conditions. Management conditions and the use of high yielding breeders accomplished the improvement in yields in different years. Two principle factors came forward in the study and highest determining factors were observed to be the farm and turn of lactation. Key Words: Holstein-Friesian, milk yield and components, somatic cell count. OZET Bu calisma, Ingiltere'deki rastgele secilmis bes ayri ozel isletmede yetistirilen Siyah-Alaca sigirlarin laktasyon sureleri, gercek ve 305 gunluk sut verimleri, sutteki yag ve protein oranlari ile somatik hucre sayilarinin belirlenmesi, bu verimler uzerinde bazi cevre faktorlerinin etkilerinin incelenmesi amaciyla yapilmistir. Arastirmanin materyalini 1994-2003 yillari arasinda yetistirilen Siyah-Alaca sigirlardan elde edilen 2514 verim degeri olusturmustur. Siyah-Alaca sigirlarin verim degerlerinin istatistik analizlerinde GLM prosedurunden contrast-testi kullanilmistir. Incelenen sut verimi ozelliklerinden laktasyon sureleri, gercek ve 305 gunluk sut verimleri, sutteki yag ve protein oranlari ile somatik hucre sayisina ait genel ortalamalar 324,32 gun, 7715,23 kg, 7218,62 kg, %4,028, %3,333 ve 137.998 hucre/ml olarak belirlenmistir. Calismada, etkileri arastirilan faktorlerden hayvanlarin yetistirildikleri ciftligin ve laktasyona baslanan yilin tum ozellikler uzerinde P<0,001 duzeylerinde, yine laktasyon sirasinin da bu ozellikler uzerinde, laktasyon suresi uzerinde P<0,05 duzeyindeki etkisi disinda, ayni duzeyde onemli bir faktor oldugu belirlenmistir. Mevsimin ise, gercek sut verimi ve sutteki somatik hucre sayilari uzerindeki etkisi onemsiz olarak bulunmustur. Ancak, mevsim faktorunun diger faktorler gibi laktasyon suresi, sutteki yag ve protein oranlari uzerinde P<0,001 ve 305 gunluk sut verimi uzerinde P<0,01 duzeylerinde onemli etkisinin oldugu bulunmustur. Bu arastirmada elde edilen sonuclar, isletmelerin sigir yetistiriciligi icin gerekli optimum kosullari saglayarak yuksek duzeyde verim elde ettiklerini gostermektedir. Hayvanlara uygulanan management ve kullanilan daha yuksek verimli damizlik materyal yillar arasinda daha yuksek verime ulasilmasini saglamistir. Calismada temel olarak iki faktor on plana cikmis ve en yuksek duzeyde belirleyici faktorlerin ciftlik ve laktasyon sirasi oldugu belirlenmistir. Anahtar Kelimeler: Siyah-Alaca, sut verimi ve sut komponentleri, somatik hucre sayisi.