Siyah alaca sığırlarda laktasyonun devamlılık düzeyine ait parametre tahminleri ve süt verimi ile ilgisi üzerinde araştırmalar /
Yazar: İBRAHİM KAYA
Danışman: Y.DOÇ.DR. ATTİLA KAYA
Ege Üniversitesi / Fen Bilimleri Enstitüsü / Zootekni Ana Bilim Dalı
Derece: Doktora, 1996
Konu: Ziraat = Agriculture
Dizin: Laktasyon = Lactation ; Parametre tahmini = Parameter estimation ; Siyah alaca sığırlar = Holstein friesian cattles ; Süt verimi = Milk yield ; Zootekni = Zootechnics

Özet:
IX KISA ÖZET Bu araştırmada, S. Alaca sığırlarda laktasyonun devamlılık: düzeyi ve süt verim ölçütlerini etkileyen faktörler incelenmiş, laktasyonun devamlılık düzeyi ve süt verim ölçütlerine ilişkin genetik parametre tahminleri yapılmıştır. Ayrıca, devamlılık düzeyi ölçütlerinin tercih edilebilirliği incelenmiştir. Çalışmada, Tahirova, Dalaman ve Türkgeldi Tanm İşletmesi ile Sarımsaklı Tohum Üretme ÇifUiğTnde yetiştirilen S. Alaca sığırlara ait veriler incelenmiş ve 1259 ineğe ait, süresi en az 270 gün olan toplam 2845 laktasyon değerlendirilmiştir. Laktasyonun devamlılık düzeyini hesaplamak amacı ile Pii, P3:i, P32 ve Pr

Abstract:
ABSTRACT Parameter Estimates for Persistency of Lactation and Relationship of Persistency with Milk Yield in Holstein Cattle In the present study, factors affecting persistency and milk yield in Holstein cattle were investigated. Genetic parameters were estimated for persistency and milk yield. Measures of persistency of lactation were also compared. In the study, data collected from cows raised in the Tahirova, Dalaman, Türkgeldi and Sarımsaklı state farms located in the western part of Turkey were analyzed. The data consisted of 2845 lactations with a length of least 270 days of 1259 Holstein cows. Persistency of lactation was calculated by P^i, P3:i, P^a and P-roma* (305-day lactation milk yield / milk yield in the first 50 days (initial milk yield)) measures. The effect of sire, herd, lactation number, calving season, service period and calving year on persistency of lactation were significant for all measures. First lactations were more persistent than later lactations for all measures of persistency. Genetic parameters were estimated for the each herd. Repeatability estimates for the measures of persistency of lactation ranged from 0.05 to 0.27. Most of the heritability estimates for the four measures of persistency of lactation were between 0. 10 and 0. 19. Heritability of P3.i was higher than those of Pxi, P32 and Ptomk in all herds, except Dalaman herd. Phenotypically, initial milk yield and 100-day milk yield were negatively correlated with the four measures of persistency in all herds. Genetic correlations of initial milk yield and 100-day milk yield with measures of persistency were also negative and mostly moderate in Tahirova, Dalaman and Türkgeldi herds. Whereas, most of the genetic correlations of initial milk yield and 100-day milk yield with measures of persistency were around zero and some estimates were positive in Sarmisakli herd in which herd milk yield was rather higher than those of the other three herds. Phenotypic correlations between the four measures of persistency and 305-day milk yield were positive in aH herds. Genetic correlations between measures of persistency and 305-day milk yield were also positive, except some negative estimates in Dalaman and Türkgeldi herds. Genetic correlations between measures of persistency and 305-day milk yield were highly positive in Sarmisakli herd in which the average 305-day milk yield was the highest. Phenotypic correlations between the four measures of persistency were positive and mostly high in all herds, except phenotypic correlations which were low and negative or around zero between P^i and P32 measures. Genetic correlations between the four measures of persistency were positive and mostly high. Pxi, P3.1, P32 and Ptotok measures were also compared. Pm measure was recommended because its heritability was higher and there were high and positive genetic and phenotypic correlations between P^i and the other three measures.