Growthcharacteristics in lambs of estrus synchronized ewes in grower conditions

Abstract

The aim of this study was to determine the growth characteristics of lambs of estrus-synchronized ewes in an extensive production system during 2 different periods. The animal material of this study was composed of 325 head Chios × Ki{dotless}vi{dotless}rci{dotless}k cross breeds. These lambs were provided by mating 124 Ki{dotless}vi{dotless}rci{dotless}k sheep on 2 farms with8 Chios rams provided by the Adnan Menderes University, Faculty of Agriculture, Sheep Research Unit. The estrus cycles of the ewes were synchronized wiThintra-vaginal progestagen sponges impregnated with30 mg of cronolone. After 12-14 days the sponges were removed, the females received an intramuscular injection of 500 IU PMSG, and 5 or 6 ewes were mated with Chios rams. This research lasted for 3 years, and detailed flock records were kept. The average birth weight, average weight of 100-day-old lambs, and average marketing weight of Ki{dotless}vi{dotless}rci{dotless}k × Chios F 1 were 3.18 kg, 19.71 kg, and 29.10 kg, respectively. Lambing season, birth type, and the sex of the lambs were found to significantly affect birth weight, which is an important factor in lamb production (P < 0.01). In this study daily gains in the live-weight of 100-day-old lambs and daily gains in the live-weight during the marketing period were 163.07 g and 167.48 g, respectively. Year of birth, lamb sex, and growing methods were significant in determining the characteristics mentioned (P < 0.01). In addition, the 100th day performances indicated significant changes according to the farms, and the performances during the marketing period varied significantly according to the ages of the ewes. The survival rates of lambs up to 100 days of age and the marketing period were 66.81% and 63.57%, respectively. The effect of year was also significant (P < 0.01). The results of this study indicate that, with respect to lamb development and marketing, more advantageous results can be achieved by synchronizing estrus and having earlier births than traditional production methods allow. © TÜBİTAK.