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Articles by Hend A. Radwan
Total Records ( 4 ) for Hend A. Radwan
  Hend A. Radwan and Eman A. ABO Elfadl
  Objective: Test day milk average somatic cell count is a frequently used indirect indicator of infectious status of mammary glands. Therefore, the aim of this study was to compare the efficiency of using cumulative milk yield or test day milk yield as a criterion to improve milk production based on measures of somatic cells in milk. Methodology: This study was carried out during the period extended from year 2008-2010 on 1739 dairy records for 858 cows by 86 sires US Holstein from Dina farms situated about 80 km in Cairo-Alexandria desert road. Variance components, heritability estimates, genetic, phenotypic and Spearman’s rank correlations between breeding value for somatic cell score and both cumulative milk yield and test day milk yield in first six months of lactation period were analyzed by using a multi-trait animal model analysis. Results: According to the results of the study, there is a direct relationship between somatic cell count score and somatic cell count, the highest score (9th) was observed when somatic cells being 8517.36 cells mL–1. Conversely, test day milk yield was inversely affected by somatic cell count score, the highest test day milk yield (50.63 kg) was obtained with the lowest score of somatic cells. Additive genetic variances based on somatic cells were low compare to permanent environmental variances. Thus, the possibility of improving these traits is small and takes a long period of time. Conclusion: Finally, it could be concluded that test day milk yield has the possibility of selection for milk yield based on somatic cell measures before the end of lactation mainly at the first two thirds of lactation season enabling inclusion of cows with incomplete lactations in the genetic evaluation which may resulted in improving generation interval, intensity of selection and enhance the genetic progress.
  Hend A. Radwan , Eman A. ABO Elfadl and Khairy M. El-Bayoumi
  Objective: This study aimed to detect the effect of inclusion of maternal genetic effect on variance, covariance components and genetic parameters of some productive traits in Holstein cows. Methodology: First milk production data set and pedigree information were collected from 991 Holstein dairy cows during the period from 1994-2011. Records were pre-adjusted to mature equivalent yields (ME-2X-305d). Three different animal models were fitted, which were differentiated by including or excluding maternal genetic effect. Results: Direct and maternal genetic variances and heritabilities were high in model 2 which account for maternal effect with cov (a,m) = Aσam. The highest direct and maternal genetic variances were 39846.9 and 4583.2 kg for LMY and 305 ME, respectively. In the same line, the highest direct and maternal heritability estimates were ranged from 0.233 for DO to 0.438 for DIM, however, the maternal heritability ranged from 0.021 for DO to 0.104 for 305 ME. Additive genetic values were estimated and used to characterize genetic trend across the time period investigated. Ranges of breeding values were high in model 3 which account for maternal component with cov (a,m) = 0. Conclusion: In summary, the first lactation milk yield traits can be used as selection criteria for development an efficient selecting and breeding programs and maternal genetic effect should include during constructing breeding plans in order to select future generation improved genetically.
  Hend A. Radwan and Nazem A. Shalaby
  Background and Objective: Average daily gain trait of lambs at different ages has a very important effect on the profitability of sheep production systems. Developments of effective selecting and breeding programs for genetic optimization the growth rate of the lambs require accurate covariance components and genetic parameters estimates. The aim of this study was to estimate variance, covariance components and genetic parameters for average daily gain traits from birth to weaning (ADG0,3), from weaning to 6 months (ADG3,6) and from birth to 6 months age (ADG0,6) in Rahmani sheep flock maintained at El-Serw Experimental Station, over a period of 10 years (1991-2001), show the effect of the including or excluding maternal components during the genetic evaluation of the traits under study, clarify the most appropriate animal model and rank them according to Akaike Information Criterion (AIC). Materials and Methods: Records of growth traits of 5879 lambs, offspring of 1766 ewes and 299 rams were used in the study. Analysis were carried out by 6 single and multi-trait animal models based on including or excluding to maternal components and locating the most appropriate model for the analysis average pre and post-weaning weight gain traits by determining the akiake information criterion and testing the log likelihood values. Results: Since, the log likelihood of the first and second models were non-significant, which indicates the amount of maternal permanent environmental effect was negligible. Conclusion: It could be concluded that the simple model is the best model in designing of breeding programs for average daily gain traits in Rahmani lambs. A modest rate of genetic improvement could be achieved in the flock through selection. Maternal permanent environmental effects contributed 7 and 29% of the total phenotypic variation in ADG0,3 in single and multi-trait analysis, respectively.
  Eman A. ABO Elfadl and Hend A. Radwan
  Objective: The study aimed at selecting the accurate model helps in improving productive traits in dairy population through compare between inclusion and exclusion of maternal genetic effect in estimating variance components and genetic parameters of those traits. Methodology: Data set and pedigree information were collected from 3464 Holstein-Friesian dairy records for 991 cows descended from 99 bulls and 691 dams calved over a period of 17 years (1994-2011) for three consecutive lactations. Three multi-trait animal models were fitted to estimate covariance components and corresponding genetic parameters. Results: The highest direct and maternal genetic variances were in model 2 which account for covariance between direct and maternal genetic effect. Mostly, phenotypic variances were high in full animal model for first and second lactations but in third lactation the highest being in model 3. Direct and maternal heritability were high in model 2 in three lactations except direct heritability for days in milk in second lactation and days in milk, 305-day milk yeild mature equivalent, fat yield and protein yield in third lactation. Ranges and standard deviations of breeding value varied between different models but often they were high in model 1 and 3. Conclusion: Results highlight the importance of inclusion of maternal genetic effect in designing an appropriate selective and breeding program to obtain accurate estimates of genetic parameters especially if the variation between animals is high.
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