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Articles by M.T. Beigi Nassiri
Total Records ( 3 ) for M.T. Beigi Nassiri
  M. Nazari , M.T. Beigi Nassiri , J. Fayazi and S. Tabatabaei
  In order to estimate variance components 8843 test day milk and fat yields records from first lactation Najdi cattle were used. Data obtained between years of 1989-2005 by animal breeding station of Najdi cattle located in Shooshtar city. Random regression models were studied in respect of different orders of fitting for fixed and random regression. Also, different methods of residual variance in the statistical model assume that included assumption of constant residual variance and different assumption about variable residual variance during lactation. According to the obtained results, the assumption of heterogeneous residual variance during lactation improved characteristics of statistical model. A suitable model with (3, 3) orders of fit for additive genetic and permanent environmental covariance functions to analyze TD fat and milk yield records were recognized. Minimum of heritability for fat and milk yield was estimated at the beginning of lactation (0.1, 0.15), respectively. The amount of this parameter increased to mid lactation and almost in the 5th month of lactation reached to maximum level (0.34 for milk yield and 0.44 for fat yield), then decreased to the end of lactation.

Key words: Random regression, milk and fat yields, Najdi cattle, residual variance, Iran

  M.T. Beigi Nassiri , Z. Biranvand , T. Hartatik , J. Fayazil and S. Tavakoli
  The part of the bovine genome which shows a superior action and explains the major part of variation of the economical production traits were known as QTL. PIT1 gene which is also termed hormone factor-1 is a pituitary-specific transcription factor which has responsible for pituitary development and hormone expression in mammals. The main function of PIT1 is for binding and trans-activity promoters of both Growth Hormone (GH) and Prolactin (PRL) gene. It was subjected to different molecular studies as a key role for understanding genetic variation in dairy cattle. This study was aimed to detect the polymorphism in a part of PIT1 gene, exon 6 in Najdi cattle. DNA was extracted from blood sample collected from 84 Najdi Cattle and submitted for Polymerase Chain Reaction (PCR) followed by digestion with HinfI restriction enzyme. Base on PCR-RFLP method, it found that the frequency of the A and B alleles of this gene for Najdi Cattle were 18.45 and 81.55%, respectively. The genotypic frequencies of AA, AB and BB were 3.57, 29.76 and 66.66%, respectively. χ2-test indicated that these two populations were at Hardy-Weinberg equilibrium. Thus, the selection base on these loci in the population is possible to be done.
  K. Mohammadi , M.T. Beigi Nassiri , H. Roshanfekr , K. Mirzadeh and A. Aghaei
  Data from body weights at post-weaning were used to genetic trend for Zandi sheep reared in Khojir breeding station of Tehran-Iran over a 16 years period (1993-2008) using animal model for lambs, rams and ewes. Genetic trends were estimated for 6 Months Weight (6MW), 9 Months Weight (9MW) and Yearling Weight (YW) traits. For investigation of each trait appropriate models using 3-trait analysis were applied. Breeding values of animals were predicted by Best Linear Unbiased Prediction (BLUP) methodology under three-trait animal models. Genetic trends of studied traits were estimated by regressing mean of breeding values on birth year. The genetic trends were positive and significant for 6MW, 9MW and YW and were 21, 72 and 65 g year-1, respectively.
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