Livestock Studies 2007, Vol 47, Num, 2     (Pages: 007-013)

Comparision of various models for lactation curves of Akkaraman and its crossbreds (Chios x Akkaraman F1 and Kıvırcık x Akkaraman F1 ) ewes

Necmettin ÜNAL 1 ,Mehmet Nurullah ORMAN 2 ,Cemil ÇOLAK 3 ,Fatih ATASOY 1 ,Durhasan MUNDAN 4 ,Melik AYTAÇ 5

1 Ankara Üniversitesi Veteriner Fakültesi Zootekni Anabilim Dalı, Dıskapı – Ankara
2 Ege Üniversitesi Tıp Fakültesi Biyoistatistik Anabilim Dalı, İzmir
3 Türk Standartları Enstitüsü, Ankara
4 Harran Üniversitesi Veteriner Fakültesi Zootekni Anabilim Dalı, Şanlıurfa
5 Lalahan Hayvancılık Merkez Arastırma Enstitüsü, Lalahan – Ankara
Viewed : 129 - Downloaded : 85 The various models to represent the lactation curves of Akkaraman (A) and Kıvırcık x Akkaraman F1 (KAF1) and Chios x Akkaraman F1 (CAF1) ewes were examined. Fort this purpose, the models of Wood, Dhanoa, Wilmink, Cobby & Le Du, Dave and Nelder were compared. Animals used in the study were consisted of 10 A and 10 KAF1 and 16 CAF1 ewes, and all ewes were on the first lactation number. The models were evaluated according to determination coeefficient, mean square errors and iteration number. Because of very low determination coefficients, the lactation curves of Cobby & Le Du, Dave and Nelder in all genotypes were not fitted. Wilmink model was determined as the best fitting model in all genotypes according to fitting criterions. The determination coefficients of Wilmink model in A, KAF1 and CAF1 genotypes were calculated as 79.0, 86.0 and 83.0 %, respectively. As a result, the best fitting model for lactation curve in A, KAF1 and SAF1 was Wilmink model and this one was followed by Wood and Dhanoa models, respectively. Keywords : Sheep, Akkaraman breed, Crossbreeding, Non-linear regression analysis, lactation curves