Mojdeh Mahmoudi Zarandi; Mohammad Rokouei; Mehdi Vafaei Valleh; Ali Maghsoudi
Volume 22, Issue 1 , Winter 2020, , Pages 9-22
Abstract
This study was done in order to estimate genetic parameters of growth and feed efficiency traits in Japanese quail. The data set consisted of 7762 records for feed efficiency traits and 12113 records for body weight gain traits were collected at Research Center of Special Domestic Animals, University ...
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This study was done in order to estimate genetic parameters of growth and feed efficiency traits in Japanese quail. The data set consisted of 7762 records for feed efficiency traits and 12113 records for body weight gain traits were collected at Research Center of Special Domestic Animals, University of Zabol. The following traits including body weight gain from 20 to 25, 25-30, 30-35, 35-40, 40-45 and from 0 to 45 days of age, feed intake, feed conversion ratio and residual feed intake from 20 to 45 days of age were evaluated. The genetic parameters were estimated through single and bivariate animal models via Gibbs sampling method. Heritability estimates for body weight gain varied from 0.02 to 0.23 and for feed intake, feed conversion ratio, residual feed intake was in ranges of 0.04 to 0.11. Genetic correlations estimates between body weight gain and feed conversion ratio 20-25, body weight gain and feed conversion ratio 25-30, body weight gain and feed conversion ratio 30-35, body weight gain and feed conversion ratio 35-40, body weight gain and feed conversion ratio 40-45 were -0.56, -0.49, -0.57, -0.70 and 0.25 respectively. Considering estimated genetic correlations of this study, we recommend that selection for body weight gain and decrease feed efficiency have potential to improve feed efficiency traits in Japanese quail. It is expected that by selecting for these traits the costs of breeding programs such as feeding and phenotyping would be reduced.
Ali Vojdan Hassan Kiyadeh; Mohammad Rokouei; Gholam Reza Dashab; Ahmad Reza Seyedalian; Hadi Faraji- Arough
Volume 21, Issue 2 , Summer 2019, , Pages 181-192
Abstract
This research was conducted with the aim of estimation of environmental factors affecting survival and estimate the genetic parameters survival from 1 to the last recording date in Zandi sheep. The survival records of 9558 Zandi sheep from 273 rams and 2328 ewes collected by Animal Breeding Center of ...
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This research was conducted with the aim of estimation of environmental factors affecting survival and estimate the genetic parameters survival from 1 to the last recording date in Zandi sheep. The survival records of 9558 Zandi sheep from 273 rams and 2328 ewes collected by Animal Breeding Center of Iran during the 25 years (1987 to 2011) were used in the analysis. The effective factors on survival and culling risk were estimated by Survival and cmprsk package. Estimation of variance components was performed by using of exponential distribution for censored dates by the fitting of model with additive genetic effect (model 1) and joint additive genetic and maternal permanent environmental of effects (model 2) under Bayesian approach and Gibbs sampling. A total of 1000000 samples with a burn-in of 100000 and a sampling interval of 75 were generated to estimate the posterior distribution of variance components. The results showed that year, month, birth weight, type birth, sex (P<0.001) and dam age (p<0.01) had significant effect on survival trait. the direct heritability of survival trait using models 1 and 2 was 0.184( 0.136-0.264) and 0.162( 0.120-0.202), respectively. the proportion of permanent variance to phenotypic variance was 0.046( 0.063- 0.031). According to the results of this study, genetic improvement of survival trait in zandi lamb is possible by genetic selection and the culling risk reduction is effective via management of environmental factors.
Mohadeseh Namvar; Gholam Reza Dashab; Mohammad Rokouei; Hadi Faraji Arogh; Davoud Ali Saghi
Volume 19, Issue 2 , Summer 2017, , Pages 281-298
Abstract
This study was performed to compare different models for estimation of direct and maternal heritability and also for obtaining of genetic trend for body weight traits in Kurdi sheep of North Khorasan. The records of body weight in birth (BW, 7345 records), 3-month (3W, 5905 records), 6-month (6W ,5294 ...
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This study was performed to compare different models for estimation of direct and maternal heritability and also for obtaining of genetic trend for body weight traits in Kurdi sheep of North Khorasan. The records of body weight in birth (BW, 7345 records), 3-month (3W, 5905 records), 6-month (6W ,5294 records), 9-month (9W, 3800 records) and 12-month (12W, 3863 records) weight that collected during 1990 to 2013 by Sheep Breeding Station of Shirvan were used. Estimation of genetic parameters for different traits by using of six animal models was carried out by ThrGibbsf90 software. The most suitable model for each trait was determined based on Deviance Information Criterion (DIC). The estimates of direct heritability for BW, 3W, 6W, 9W and 12W traits were 0.172± 0.0007, .0.257± 0.0007, 0.351± 0.0006, 0.120± 0.0007 and 0.131± 0.0009, respectively. In this study, the material genetic effect was significant for BW, 3W and 6W traits (P<0.01) and proportion of maternal permanent environmental variance to phenotypic variance was varied from 0.055 (12W) to 0.186 (BW). Although estimated heritability of maternal effects for body weight was lower in older ages, the result of this study showed that including maternal effects (maternal genetic and permanent environmental effect) in the statistical model could lead to more accurate estimation of genetic parameters for growth traits in all ages. The phenotypic trend for BW, 3W, 6W, 9W and 12W were 8.4, 74.6, 8.3, 54.3, 78.3 gr/year, respectively and direct additive genetic trend for mentioned traits were -0.07, 14.2, -21.9, 13.7, 24.9 gr/year, respectively. Therefore, the results of bayesian analysis are more reliable than convientioal statistical methods.