Investigation the crossbreeding of Zandi ewes with Romanov rams and comparison the performance of crossbred with pure Zandi lambs up to weaning age

This study was carried out to investigate the crossbreeding of Zandi ewes with Romanov rams, and to compare the production performance of crossbred lambs up to weaning, in Qom province.
In October 2013, a total of 297 Zandi ewes, which at least two months have been passed from their lambing date, were selected and were treated using estrus synchronization. 13 days later, as cider withdrawal, each ewe was given 500 IU of PMSG using intramuscularly injection. Afterwards, ewes were divided into 2 groups of 147 and 150. Ewes of first group were inseminated using the Romanov frozen sperm through laparoscopic procedure. Ewes of second group were mated with same flock rams for two estrous cycles (34 days). In the breeding season, all ewes lambing was recorded and birth weight, weaning weight and lamb mortality rate up to weaning were recorded in each group. Experimental groups were compared using GLM procedure of SPSS (16) for parametric data and using Mann-Whitney test for nonparametric data.
Results indicated that pre-weaning mortality rate of Romanov-Zandi lambs and Zandi lambs were 3.8 and 9.5 percent, respectively, and there were not any significant differences between the two groups. The weaning weight of Romanov-Zandi lambs and Zandi lambs were 26.45 and 21.2 (P Crossbreeding of Zandi ewes with Romanov rams produced crossbred lambs with acceptable vitality and higher weaning weight and pre weaning average daily gain. Therefore, this process could help for increasing of production efficiency of sheep farms considering native breed conservation. Results indicated that laparoscopic insemination to breed Zandi ewes with Romanov rams was not very efficient, and it is necessary to use more effective way for mating Romanov rams with Zandi ewes for future crossbreeding programs.