جستجوی مقالات مرتبط با کلیدواژه « romanov‎ » در نشریات گروه « علوم دام »

 Iranian sheep breeds, due to the climate diversity of country, show high diversity and have acquired high adaptability. Compromise with poor quality feed, tolerance of adverse weather and manageable body size are among the factors that probably caused sheep to adapt to different climates. Heretofore, several studies have been carried out in the field of identification of selection signatures in the different native breeds based on SNP-chip data. However, the use of whole genome data can provide researchers with more information about the differences between breeds and their genetic capacities. Identifying and evaluating the effects of climate on the genome of native breeds of Iranian sheep can be effective in designing breeding and conservation strategies. The aim of the present study was to identify the signs of selection related to Iranian sheep compared to the Romanov breed at the genomic level.

 For present study, we used the whole-genome sequencing data related to 43 Iranian and non-Iranian sheep available in the NCBI database. These reads, after performing quality control, were aligned to the sheep reference genome by BWA program. Here, RealignerTargetCreator and IndelRealigner commands available in the GATK program were used to realign around insertions and deletions. Then, the HaplotypeCaller algorithm was used to identify the variants of all samples in ERC GVCF mode. Further, using GenotypeGVCFs module, the variants of all samples were simultaneously identified and finally a VCF file containing raw variants was created. Using the SelectVariants command of the GATK program, all SNPs were separated from other variants. After applying multiple quality filters, high-quality SNPs were extracted and only bi-allelic SNPs present in autosomal chromosomes were used for downstream analysis. Putative selection signatures were identified by using two methods including Fst and XP-EHH. Genes located in positively selected genomic regions were extracted using BEDtools program and the GTF file related to the sheep genome. Gene ontology (GO) analysis was performed on selected genes by "g:Profiler" web-based tool.

Here, Fst and XP-EHH methods were used to identify the signatures of selection related to Iranian sheep in comparison with Romanov sheep. After converting Fst values ​​to ZFst, 958 genomic windows containing 907 protein-coding genes were detected that had scores above the threshold (ZFst > 3.35). GO analysis on 907 genes identified by the ZFst method led to the identification of 157 significant GO terms in the field of biological processes. In addition, 26 significant terms related to molecular functions and 5 significant terms related to cellular components were also identified. The number of genomic windows identified by the XP-EHH method was 953, which contained a total of 311 protein-coding genes. Among identified genes for each method, 29 genes were detected by both methods as signatures of selection for Iranian sheep. From the GO analysis of 29 common genes, no significant term was obtained. However, these genes were involved on traits related to improving milk fat quality (PCCB), fertility (SPATA5, RAB35 and DICER1), muscle growth and development (NF1, AKAP6 and HDAC9), body weight (FBXL3, GRID2 and ADAMTS17), adaptability to harsh desert and mountain condition (BMPR2 and NF1) and also, milk related traits (EXOC6B).

The results showed that Iranian sheep were probably selected to adapt to dry desert areas and improve the quality of meat and milk. The gradual accumulation of such information in different populations will improve the understanding and knowledge of researchers and breeders and will help them to implement efficient breeding programs.

The objective of this study was to compare growth performance, birth and weaning body weights, and survivability between purebred Balouchi (n=53) and crossbred Balouchi×Romanov (n=114) lambs. In addition, carcass characteristics (n=24) were determined. Balouchi ewes were inseminated with Romanov semen to produce crossbred lambs. All experimental lambs were weaned at 77 d of age and slaughtered at 10 months of age. Birth body weight of the purebred Balouchi lambs was significantly greater than for the crossbred lambs (3.75 vs. 3.56 kg, P<0.01). However, weaning body weight and average daily gain from birth until weaning and slaughter were greater (P<0.05) for the crossbred lambs than for the purebred lambs. Slaughter body weight at 10-month age were not different brtween the tow groups  (P=0.08). Litter size was also increased by crossbreeding and using hormone (1.13 vs. 1.00), but lamb survivability was not different between the two groups. The fat yield decreased with crossbreeding. Crossbreeding increased (P<0.05) the weights of testis, liver, heart, and lung. It is concluded that crossbreeding Balouchi ewes with Romanov semen resulted in improved litter size, weaning and slaughter body weights, average daily gains from birth until weaning and slaughter, and carcass characteristics without affecting lamb survivability. Therefore, crossbreeding can be a profitable strategy to increase lamb (meat) production in Balouchi sheep.

Reproduction is directly affected by various management related factors. Manipulation of these factors can cause changes in reproductive performance. The reproductive performance is considered as the most important factor in determining the profitability of ruminant breeding. Estrous synchronization and supper ovulation are considered as the two valuable management tools used to increase the efficiency of reproduction in small ruminants and seasonal breeder animals, thanks to the use of hormonal therapies The control and manipulation of the sheep reproduction has been the objective of scientists around the world for many years. Identifying the appropriate foreign and indigenous breeds to improve reproductive performance is an essential requirement for self-sufficiency of sheep products. Intensive lamb production systems involve the obtention of more than one lambing per ewe per year. Accelerated lambing systems require the implementation of two, three or even five breeding periods at different times of the year. The purpose of this study was to investigate the effects of using CIDR and PMSG as an appropriate method of concomitant with artificial insemination of imported ewes and comparing them with native Iranian ewes on reproductive performance. 

 The experiment was conducted at the Research Unit Farm of the Light Livestock Breeding Center of the Water and Soil Conservation Company, located in the southern Khorasan province, Iran. 180 ewes with average weight of 50 ± 1.5 kg were divided into 6 groups of 30 rats based on internal and external breeds including: 1- Romanov group 2- Sharouleh group 3- Suffolk 4- Baluchi 5- Mogani group 6- Afshari were selected. Estral synchronization was performed in spring with CIDR. Ewes after CIDR (14 day) extraction and PMSG injection as soon as the signs of estrus were observed, the ewes were isolated from the others and artificially inseminated with fresh sperm using the transcortical method. Ultrasonography examination was performed by an ultrasound device (6 MHz linear probe, ECM model, France). The nutrition program with software (SRNS) version was adjusted based on the pregnancy diet. Investigation of the number of graafian follicles (follicles larger than 4 mm), was examined simultaneously with CIDR removal and estrus observation. Then, in each experiment parameters such as the time of estrus initiation (hour), rate of return to estrus, parturition rate, rate of multiple births, number of lambs and rate of lambing were evaluated.  

There were no difference between the experimental groups in terms of estrus symptoms. Results showed that Ovarian ultrasound at day 10 postoperatively showed that the number of lutein in foreign races was higher than other races and significant statistical differences were observed (p<0.05). The results of the present study showed that the mean daily body weight change of ewes was affected by experimental groups (p<0.05). Ovulation in most ewes, depending on the breed, occurs at a fixed time in relation to the onset of estrus. The breed of ewe could be one of the factors influencing the time of ovulation. Results Ovulation rate, Pregnancy rate, stillbirth rate, was significant difference in fertility rate and twinning rates between the groups (P <0.05). The highest ovulation rate (100%), pregnancy rate (100%), The fertility rate (160%) and Twinning rates (66%) belonged to the Romanov group and statistical differences were observed (p<0.05). Variability between results could be attributed to different protocols, management systems, nutritional status or physiological status resulting from diverse experimental conditions. Furthermore, these variable results may indicate that breed, timing of treatment or doses used in these treatments produce critical effects on fertility rate and embryo survival. 

In general, the use of some new technologies such as estrous cycle control and the use of hormones was effective in this study and increased the average production of lambs per ewe mixed in the herd. Significant differences between Romanov ewes in pregnancy rate, lambing rate and twinning with other breeds indicate the high genetic capacity of this breed of sheep in the success of reproductive performance. Due to low productivity of Iranian breeds compared to foreign breeds, it can be suggested that foreign sheep be used to improve breeding efficiency of Iranian sheep for breeding.

This study was conducted to investigate the performance of growth and carcass traits of Lori-Bakhtiari (L), Romanov×Lori-Bakhtiari (F1RL), Pakistani×Lori-Bakhtiari (F1PL), (Pakistani×Lori-Bakhtiari)×(Romanov×Lori-Bakhtiari) (¼P¼R½L) and (Romanov×Lori-Bakhtiari)×(Romanov×Lori-Bakhtiari) (F2RL) crossbred lambs. Carcass characteristics of Lori-Bakhtiari (n=50), F1RL (n=41) and F2RL (n=20) crossbred lambs. Lambs were weaned at the age of 90 ± 5 days. Lambs were slaughtered at six month of age. Birth weight in Lori-Bakhtiari (5.12 kg) was significantly (P<0.05) higher than in Romanov (4.81 kg) and Pakistani (4.57 kg) crossbred. Weaning weight and body weight in six months were significantly higher (P<0.05) in Romanov × Lori-Bakhtiari crossbred lambs (30.96 and 42.75, respectively) than in Lori-Bakhtiari (28.81 and 41.69, respectively) and others genetic compositions. F1RL and F2RL crossbred lambs for lean percentage were significantly (P<0.05) higher than in Lori-Bakhtiari lambs in constant age (59.57, 60.57 and 50.03, repectively) and in constant weight (60.99, 59.24 and 49.56, repectively). Weight and percentage of total fat of carcass in Lori-Bakhtiari lambs (7.56 kg, 31.57% in constant age 6.65 kg, 30.46% in constant weight, repectively) were significantly (P<0.05) higher than of F1RL (4.25 kg, 20.91% and 4.30 kg, 20.08%, repectively) and F2RL (2.95 kg, 17.97% and 5.12 kg, 22.46%, repectively) lambs. In conclusion, crossbreeding between Romanov and Lori-Bakhtiari (F1) improves body weight at weaning and at six months of age, and carcass composition.