Growth Performance of Crossbred Lambs and Productivity of Kurdi Ewes as Affected by the Sire Breed under Extensive Production System

A crossbreeding experiment involving four Iranian fat-tailed sheep breeds, namely Kurdi (K), Chaal (C), Afshari (A) and Sanjabi (S) was carried out to determine the ram breed effects on productivity of Kurdi fat-tailed ewes (K) under extensive production system. A total of ۴۷۵ Kurdi ewes were mated to ۲۴ rams from four breeds producing ۴۵۴ lambs including pure Kurdi, KK, (۱۱۶ lambs), Afshari × Kurdi, AK, (۱۱۳ lambs), Chaal × Kurdi, CK, (۱۱۵ lambs) and Sanjabi × Kurdi crossbreds, SK, (۱۱۰ lambs). Ram breed had a significant influence on early growth traits of the lambs (P < ۰.۰۱). The lambs sired by C rams were significantly heavier at birth and weaning than the other lambs (P < ۰.۰۵). Weight at ۱۸۰ days of age (W۱۸۰) in crossbred lambs was significantly higher than that of the purebred lambs (P < ۰.۰۵) while there was no significant difference among crossbred lambs for W۱۸۰. Greasy fleece weight of lambs at first shearing (GFW) was significantly affected by ram breed (P < ۰.۰۵). Ram breed significantly influenced the fat-tail measurements of the lambs (P < ۰.۰۱). Number of lambs born and number of lambs weaned per ewe lambed or per ewe joined were not significantly influenced by ram breed effect, but the effect of ram breed on litter weight at birth and weaning per ewe lambed or per ewe joined was significant (P < ۰.۰۵). In general, ewes mated to Chaal ram had higher productivity than those mated to other ram genetic groups.

Keywords:

Crossbreeding , Early growth traits , Fat-tail measurements , Productivity of ewe