Showing 5 results for Shadparvar
Sahereh Joezy Shekalgorabi, Abdol Ahad Shadparvar,
Volume 3, Issue 6 (3-2013)
Abstract
Number of services per conception is a valuable reproductive characteristic due to its effects on different reproductive, genetic and economic parameters of herd. On the other hand, this parameter is affected by the use of reproductive technologies like sexed semen. At the current study, employing a deterministic simulation model, four different scenarios (including continuous use of conventional semen, continuous use of sex sorted semen, the use of sexed semen at the first service followed by conventional semen at remained services and the use of sexed semen at the first and the second services followed by conventional semen for the later services) were compared by their effect on number of services per conceptions in heifers. Results indicated that the average number of services was greater when continuous utilization of sexed semen comparing to the rest of scenarios (4.2±1.33). a quadratic trend was found as a result of change in number of services per conception at different conception rates. Compared to continuous utilization of sexed semen, concurrent use of conventional and sexed semen had a moderating effect on number of services per conception. Due to lower fertility of heifers from second insemination it seems that mixed use of conventional and sexed semen is a preferable scenario. However choosing the suitable scenario needs further economic consideration.
Maryam Zendedel Dalir Haghighat, Abdol Ahad Shadparvar, Mohammad Golshani, Mohammad Naserani,
Volume 6, Issue 11 (7-2015)
Abstract
Guilani sheep, with a population 900 thousand heads, produce 16% of meat and 5% of milk in this province. However, no estimation for genetic parameters of various traits in this breed has been provided up to now. The aim of this study was to estimate genetic parameters for body weight at birth (BW), three months of age (3MW), six months of age (6MW), average daily gain from birth to three months of age (ADG1) and average daily gain from three months to six months of age (ADG2). D ata were collected during 1994 to 2009 and animal model was used. The estimated heritability for BW, 3MW, 6MW, ADG1 and ADG2 were 0.20±0.045, 0.33±0.063, 0.38±0.075, 0.16±0.039 and 0.15±0.044, respectively. The estimated genetic and environmental correlations between traits ranged from 0.04 to 0.98 and 0.03 to 0.96, respectively.
Heshmatollah Askari Hemmat, Abdol Ahad Shadparvar, Seyyed Reza Miraei Ashtiani, Rasoul Vaez Torshizi,
Volume 7, Issue 13 (8-2016)
Abstract
The objectives of this research were to simulate and optimize three open nucleus breeding schemes for improvement of growth traits and carcass composition in Lori-Bakhtiari lambs with 500 ewes in nucleus using a deterministic approach. These schemes were: scheme 1 with natural mating and mating ratio (M) of 50 ewes per ram in nucleus and member flocks (base), scheme 2 with artificial insemination in nucleus (M=250) and natural mating in base (M=50) and scheme 3 with artificial insemination in nucleus (M=250) and base (M=500). An economic selection index with accuracy of 0.42 was envisaged for base and one with accuracy of 0.67 for nucleus. Advantage of open nucleus over closed nucleus for schemes 1, 2 and 3 was different but optimal relative sizes and monetary genetic lags were 7.5, 5.7 and 8 percent, respectively. With equalization of the monetary genetic lags )sub-optimal( for schemes 1 and 2 being equal to the lag of optimum scheme 1, their base population sizes were 1.035 and 3.1 times the base size of optimum scheme 1 and their monetary genetic gains were 18.9 and 21.1 percent greater than the gain of the latter scheme, respectively. In the above sub-optimal situation, the base population size of scheme 3 was 3 times that of scheme 2, its monetary genetic gain being 1.91% greater. Shifting from traditional system with selection based on body weight at 6 months of age to schemes 1, 2 and 3 with same monetary genetic lags, the monetary genetic gain increased 84.3, 119.12 and 123.3 percent, respectively. However, due to the similarity of the monetary genetic gains of schemes 2 and 3 at the same monetary genetic lags and the higher practicability of scheme 2, implementation of this scheme for ease of initiation and promotion of the open nucleus breeding system was recommended.
Jamshid Ehsani Niya, Navid Ghavi Hossein-Zadeh, Abdol Ahad Shadparvar,
Volume 8, Issue 17 (1-2018)
Abstract
This study was carried out to investigate different data transformation methods on homogeneity and heterogeneity of variance components. Data included 305-day lactation records for protein yield from the first three lactations of Iranian Holstein cows collected from 1983 to 2014 by the Animal Breeding Center and Promotion of Animal Products of Iran. Data included 141670 records for 1st lactation, 115395 records for 2nd lactation and 82529 records for 3rd lactation. Records were categorized to 3 classes according to the average of herd-year production. For testing the heterogeneity of variance components Bartlet test was used and it was significant among all three lactations. A pre-correction method and two different data transformation methods including Box-Cox and Square root were used to correct for heterogeneity of variance. Genetic parameter and heritability estimates were estimated by VCE program, under an animal model. Spearman correlations and proportion of animals selected before and after data transformation were also estimated. Application of the Visscher adjustment method resulted in slightly higher heritabilities, which may be due to the more accurate estimation of additive genetic effects when heterogeneity is considered. Heterogeneity of variance had a significant effect on re-ranking and selection of 5% top sires and 1% of top dams. Pre-correction, Box-Cox and Square root method caused a proportion of 4%, 19% and 10% of top sires and 10%, 21% and 7% of top dams, respectively, to be excluded from selection when compared to the homogenous variance scenario. The results of this research indicate that the variance between different levels of herd-year production is not homogeneous and may influence the ranking and genetic evaluation of top cows.
Dr Abbas Atefi, Dr Abdol Ahad Shadparvar, Dr Navid Ghavi Hossein-Zadeh,
Volume 11, Issue 30 (12-2020)
Abstract
This study aimed to investigate the effect of the method of estimating the effects of markers , QTLs distribution, number of QTLs, effective population size and trait heritability on the accuracy of genomic predictions. Two effective population sizes, 100 and 500 individuals, were simulated by QMSim software. A 100 cM genome including one chromosome was simulated where 500 SNPs and two different numbers of QTLs (50 and 200) were distributed on it randomly. In this study three levels of heritability (0.1, 0.3 and 0.5) were considered. Genomic breeding values were predicted using Bayesian ridge regression, BayesA, BayesB, BayesC, Bayesian LASSO, Reproducing kernel Hilbert space and neural networks. In this research, the accuracy of genomic breeding values were affected by trait heritability, effective population size, markers effect estimation methods, QTLs distribution and number of QTLs. The Bayes A and B had the highest accuracy while accuracy of neural networks method was the lowest. The accuracy of genomic breeding values were increased as the heritability of trait and number of QTLs increased while the accuracy was decreased as the effective population decreased. Considering the QTLs distribution, the highest accuracy was achieved when the QTLs distributed normally.
