بررسی عملکرد تولیدمثلی گله‌های گوسفندان قزل در استان‌های آذربایجان شرقی و غربی

Introduction: Ghezel is an Iranian medium-sized and fat-tailed sheep breed and is native in the East and West Azarbaijan provinces. Ghezel sheep plays an important role in supplying meat and milk in the region of Azerbaijan (Ghasemi-Panahi et al. 2016). Also, an important source of farmer's income is lambs production (Nabavi et al. 2015). Therefore, one of the prospects for improving the region's production is improving reproductive performance of sheep flocks. In order to suggest a proper approach to improve reproductive performance, there should be a comprehensive information from the livestock farms of these two provinces. Therefore, the present study was conducted with the aim of evaluating reproductive performance of Ghezel ewes in a couple of sheep farms in the East and West Azarbaijan provinces.
Materials and method: After designing questionnaire in this study, 30 Ghezel sheep flocks were randomly selected from different regions of East and West Azarbaijan provinces (15 flocks in each province). Then, livestock farmers of the region were interviewed using questionnaire and information on reproductive performance of flocks were collected including: pregnancy rate, multiparty, lambs' birth weight, age at the first parturition, weaning age, lambs weaning weight, number of unfertile and fertile ewes, flock surface area, farmers' education, and etc. The flocks were divided into four flock sizes. The breeding systems were also studied based on the three groups of nomadic, rural, and industrial breeding systems. The results of the questionnaires were reported as percentages (for classified data) and mean ± SD (for other data). Also, correlation coefficients between important traits were calculated using Spearman’s rank-order correlation of SAS 9.2 (2008) software.
Results and discussion: Based on the results of this experiment, 87% of the breeding systems of two provinces were rural. Other reproductive indexes of two provinces included 65% lambing rate, 79% pregnancy rate, 24% ewes' fecundity rate, 20% estrus synchronization usage, 5% flock mortality rate, 9% ewe's infertility rate, 0.1 ram to ewe ratio, and 17 months of age for ewes at the first mating. Seifi et al. (2014), with evaluating Ghezel and Afshari sheep breeds, reported low reproductive performance in these two breeds. Khodayi-Motlagh et al. (2014) reported low knowledge of farmers about the methods of estrus synchronization. However, a number of studies reported an extraordinary improvement in the reproductive performance of Ghezel ewes using different methods of estrus synchronization or using flushing rations (Najafi et al. 2014; Ghasemi-Panahi et al. 2016; Hasani Dash Tapeh et al. 2017; Ahmadzadeh et al. 2018). Therefore, it seems that improving knowledge and skill of farmers about estrus synchronization methods and/or proper rationing can improve reproductive performance of Ghezel sheep in the region. According to the correlation results, there was a negative correlation between the breeding system and the flock size (correlation coefficient: -0.6) and between the flock size and estrus synchronization usage (correlation coefficient: -0.51), (p < 0.05). These results indicated that the breeding system has been changed into the nomadic system in the larger breeding flocks and there is a less interest in the use of new methods of estrus synchronization in this kind of breeding system. Also, results indicated a significantly negative correlation (correlation coefficient: -0.42) between ram to ewe ratio and lambing rate (P <0.05). So, regardless of the role of rams on flock fertility, asymmetrical increase in ram to ewe ratio causes a negative impact on lambing rate by reducing the ewe population (which are the animals whom produce lambs). The results showed a significant positive correlation (P <0.05) between lambing rate and the age of ewes at the first mating (correlation coefficient: 0.54) and also the age of ewes at the first delivery (correlation coefficient: 0.66). These positive correlations indicate poor rearing condition of young ewes and are consistent with the general believe of farmers, which they breed ewes at the second year (age 16-18 months) to obtain optimum fertility rate. Results showed a negative correlation between the age of ewes at the first mating and birth weight of lamb (correlation coefficient: -0.60), while indicating a positive correlation between the age of ewes at the first mating and age of weaned lambs (correlation coefficient was 0.49), (P <0.05). These results can be explained by higher fecundity rate in older ewes, which reduces lamb birth weight, while it increases weaning age of lambs. The negative correlation (correlation coefficient: -0.41) between weaning age of lambs and estrus synchronization use (P <0.05) can be due to the fact that lambs from the synchronized ewes born and weaned at the same time and then, reared under better nutritional and management conditions.
Conclusion: The overall results of the present study showed low reproductive performance in the Ghezel sheep flocks of East and West Azarbaijan provinces due to the low use of estrus synchronization methods and poor management. Therefore, it seems that by informing the farmers about the new methods of estrus synchronization, raising their level of knowledge in this field, ration training, and management of synchronized animals can improve reproductive performance and increase profitability in the region.