نشریه اصلاح و به نژادی دام
پیاپی 2 (زمستان 1400)

Genetic variation among the individuals is considered as an important tool for conservation of livestock animals. Application of molecular markers to determine genetic variation between populations has been widely used in recent years. This study conducted to analyze genetic diversity using F statistics in populations of  Camelus dromedaries in north of Kerman using 8 autosomal microsatellite markers (YWLL08, VOLP03, VOLP08, YWLL38, CVR01, YWLL44, VOLP32 and VOLP67). Eighty-one blood samples were collected from Shahr-e Babak, Rafsanjan and Ravar. Total DNAs of the samples using salting out were extracted and applied for genotyping analysis. The result showed that the highest and the lowest allele number and effective alleles are shown in YWLL08 (21 and 14.9) and VOLP32 (4 and 3.11), respectively. Fixation index (FST) values for markers YWLL08, VOLP03, VOLP08, YWLL38, CVR01, YWLL44, VOLP32 and VOLP67 was obtained 0.036, 0.088, 0.080, 0.045, 0.054, 0.0698, 0.014 and 0.060, respectively. This result showed that differentiation is low between populations. The highest gene flow obtained between Shahr-e Babak population and Rafsanjan2 samples (15.83) and the lowest gene flow was observed between the two populations of Ravar (6.49). In general, it can be concluded that Camelus dromedarius in north of Kerman has approximately high genetic diversity and microsatellite markers have approximately high polymorphism and therefore can be used for genetic studies.

The objective of this study was investigation of growth performance, body and fat-tail measurements of Challmale lambs from outbreeding in Qazvin region. Two hundred 18 month old ewe lamb were divided randomly from a 1000-head flock in two groups. The first group (control) was mated with rams from same flock and the second group (treatment) mated with rams from other flock. After lambing, ten male lambs from each group were selected randomly for recording body dimensions and fat-tail measurements. Results indicated that average circumference of neck, fat-tail length at middle part and fat-tail circumference at upper part in the treatment group was significantly higher than control group (P<0.05). Birth weight, weight at two, four, six and eight months, final weight gain and body height, length body, circumference of heart girth, loin width, diagonal length, and fat-tail measurements including length at right, left and gap part; width at up, middle and down part; circumference at up, middle and down part; depth at up, middle and down part and fat-tail weight were not affected by the experimental groups (P>0.05). In total, using ram from other flocks had no effect on lamb performance.

In this research in order to identify the part of the gene polymorphism transforming growth factor beta-3 (TGFβ3) in broiler chickens Ross, polymerase chain reaction technique and single-strand conformation polymorphism (PCR-SSCP) were performed. For this purpose randomly selection was done between 200 chicks and selected chicks were bled, and genomic DNA was extracted. To determine the quality of the DNA extracted 1% agarose gel was used. Then, by using a pair of specific primers through polymerase chain reaction (PCR) gene fragment with the size of 294 bp from parts of fourth introns and entire fifth exons of the gene was amplified, and finally to determine the bands acrylamide gel and stained with silver nitrate were used. The analysis of band patterns lead to identify three band patterns AA, AB and BB, with 0.52, 0.42 and 0.06 frequency, respectively. Two alleles A and B, with a frequency of 0.73 and 0.27 in the study population was also identified. Shannon index and effective number of alleles for the TGFβ3 gene were 0.5833 and 1.6507, respectively. To confirm the results of PCR-SSCP some samples of each genotype were sequenced directly. Compare of least squares mean different genotypes showed that the gene polymorphism TGFβ3 has significant relation with leg weight and carcass traits.

In this study, genetic parameters and (co) variance components were estimated for weights at birth, 3, 6, 9 month, daily weight gain and Keliber ratio from birth to 3 month and also form 3 month to 9 month. Records of 2544 kids, the progeny of 149 sires and 851 dams were used to analysis data by MTGSAM program. Six different animal models were fitted for all traits. The most appropriate model for weight at 6, 9 and daily weight gain and Keliber ratio form 3 to 9 month was model 2. Estimated direct heritability varied from 0.01 to 0.36, which was minimum (0.01) for daily weight gain and Keliber ratio from birth to 3 month and maximum (0.36) for birth weight. The genetic and phenotypic trends for all traits were estimated near to zero and non-significant. Generally, differences between estimated genetic trends for these traits and estimated values of other studies, is due to difference in animal breeding standard followed by different program selection, difference between models and calculation method, effects of environment, interaction between genetic and environmental, nutrition and climate conditions.

The object of this study was to identify the novel nucleotide polymorphisms in the second exon of MHC-DRB1 gene that has association with genetic resistance to gastrointestinal nematodes in Iranian indigenous Ghezel sheep breed. In this investigation 100 indigenous Ghezel sheep breed male lambs in 4 to 6 months age were used that were randomly chosen from five different flocks in all over the East Azerbaijan province, In these lambs, the preliminarily nucleotide polymorphisms were identified using the PCR-RFLP technique and the relationship between these polymorphisms and fecal egg counts were investigated and also in present study four samples of PCR product randomly selected from each five flock's lambs (one sample from each flock) and were sequenced subsequently. The nucleotide sequencing results of the PCR products were aligned with other registered nucleotide sequence in NCBI (National Center for Biotechnology Information) gene bank for second exon of Ovar-DRB1 gene in various sheep breeds of world. In the results of alignments, nine novel polymorphisms (two deletions, five substitutions and two insertions) were identified in the second exon of MHC-DRB1 gene sequences of Ghezel sheep breeds. Existence of these nucleotide polymorphisms were caused to substitution of all the amino acid sequence and consequently lead to changes in the structure of foreign peptide binding cleft in the DR heterodimeric proteins in the membrane of antigen presenting cells. Existence of novel polymorphisms in the second exon of Ovar MHC-DRB1 gene has led to changes in protein structure and increased the validity of observed association between identified polymorphism and studied trait.

In order to compare the two methods of artificial neural networks (ANN) and multiple linear regression to predict yearling weight used records of 736 Raieni goat. Effects and variables influencing on yearling weight were; animal sex, type of birth, birth year, birth season, herd and characters related to birth weight, three months weight, six months weight and nine months weight. In order to process of data using a neural network model, applied the 3 MLP with a different number of input type. Data modeling were created by neural network software STATISTICA 10. In multiple regression data analyzed using software SAS 9.1.3 Protable with stepwise regression method and suitable model were selected according to R2, RMSE and bias. The results in this research showed a better accuracy of the ANN systems than regression methods (R-square value made by neural networks MLP1 to MLP3 equal to 0.998, 0.998 and 0.997 and RMSE value were estimated 0.96, 0.97 and 1.22, respectively) for predicting yearling weight of these animals.