عبدالاحد شادپرور

This study aimed to investigate the interaction effects between marker effect estimation methods, population structure, and genetic architecture of the trait on the accuracy of genomic evaluations. A reference population with two different effective population sizes (100 and 500) was simulated using the QMSim software. 500 markers and two different numbers of quantitative trait loci or QTLs (50 and 200) were distributed randomly through the genome including a 100 cM chromosome. In this study, three traits with different heritabilities (0.1, 0.3, and 0.5) were simulated. The genomic breeding values were predicted using Bayesian ridge regression, Bayes A, Bayes B, Bayes C, Bayesian LASSO, Reproducing kernel Hilbert space, and neural networks methods. Through the three heritabilities, as the effective population size increased, the accuracy of genomic evaluation decreased with different trends. As the number of QTLs increased, the accuracy of low heritability trait increased, but the accuracy of medium and high heritability traits decreased. Similarly, as the number of QTLs increased, the accuracy of the trait with normal distributed QTLs increased, but the accuracy of traits with gamma and univariate distributed QTLs decreased. For all types of QTL distributions, the increment of effective population size decreased the accuracy of genomic evaluations. The results of this study clearly showed the interaction effects between markers effect estimation methods, population structure, and genetic architecture of the trait on the accuracy of genomic evaluations.

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.

Genomic information offers new possibilities to control the level of progeny inbreeding. Traditionally, mating plans constrain the inbreeding of predicted progeny by using a matrix of relationships among individuals. In this study aims to improve genetic gain and restrict the inbreeding level of progeny, a founder population, with effective population size 1000 and 1000 generations, was simulated using the QMSim program to generate linkage disequilibrium. Thereafter, 500 males and 500 females were used to generate a secondary 10-generation population, with 1000 individuals per generation and its corresponding phenotype and genotype in SNP terms. Five hundred sires and 500 dams from generation 1010 were randomly selected to create generation G0 and a trait with heritability of 0.3 was simulated. The eight strategies consisting of two mating designs: minimum_inbreeding (minf) and random (rnd) and four relationship matrices as matrices of A, GRM, IBS and Weighted were used to estimate breeding value for ten generations. Comparison of strategies showed that type of mating designs and different relationship matrices had significant effect on amount of genetic gain, homozygosity and inbreeding (p < 0.05). The type of relationship matrix affected the accuracy of predictions. In strategies with weighted matrix (Gweighted), average of genetic gain during 10 generations was less than strategies using A, GRM and IBS matrices. In strategies with random mating, inbreeding rate had increasing trend. Accuracy of selection (0.63) in strategies with A matrix was lower than other strategies. In general,

The present study was aimed to assess the role of genotype× environment interaction (G×E) and generation interval on the genetic gain caused by importing the genetic materials of dairy cattle in a country without advanced breeding program. Changing allele substitution effects of quantitative trait loci (QTLs) underlying the trait was used to simulate G×E. To this end, three levels of 100 (control), 75 and 50% overlapping of QTL effects in imported sires at the heritability levels of 0.1, 0.3, and 0.5, as well as three scenarios of continuous replacing and discontinuous replacing with one and two generations of foreign genetic materials were considered. Moreover, the effect of decreasing the accuracy of genomic prediction in traits with the low level of heritability was investigated. Based on the performance of daughters of sires in the local population of control scenario, import-based strategies were better than on the strategies of local population. The genetic correlation created in 75% and 50% overlapping of QTL effects were as 0.7 and 0.5, respectively. Although the trend of genetic response increased by decreasing genetic correlation over the time, it was not equal to origin population. Maximum genetic gain (2.56) was observed with a heritability of 0.5 in continuous replacing and absence of G×E. A decrease in the accuracy of prediction resulted in exacerbation of G×E. In general, more genetic improvement is transmitted from origin population to local population only by importing the genetic materials related to populations with higher genetic mean and also by considering G×E in different traits.

Persian sturgeon (Acipenser persicus) is one of the most valuable species of fish native to the Caspian Sea and Iran's waters. This study was designed to estimate heritability of Persian sturgeon eggs. In this study, 3 wild Persian sturgeons caught from the south coast of the Caspian Sea in Guilan and transferred to fish breeding programs in Shahid Beheshti rearing and propagation complex were used during 2016. Characteristics including the weight and diameter of eggs at blastula, gastrula and neurola embryological stages. To estimate heritability, 270 eggs were sampled at each stage of fetal development. Variance components was estimated using software R linear mixed model (LMM) closed Lme 4. Results showed that heritability of eggs weight and diameter  at blastula stage 0.218±0.422 and 0.375±0.145 ,at gastrula stage  0.033±0.062 and 0  and at stage neurola was  0.377±0.45 and 0.272±0.564 , respectively. Genetic value in female 3 and male 3 brood stocks was 0.787 and 0.287, respectively. Correlation between these two variables 0.106, 0.44 and 0.43, respectively. Overall, heritability of average egg weight and diameter showed that selection for these traits could be had a positive source of genetic origin.

One of the breeding programs for sheep is the nucleus breeding scheme (Kosgey and Okeyo 2007). The nucleus breeding system, including open or close nucleus, is a good start for genetic improvement in many populations. Unlike the close nucleus schemes, there is a reciprocal gene flow in open nucleus schemes, where the best animals from base layer could be transferred to the nucleus layer (Kosgey et al. 2006). In the original nucleus breeding scheme, a constant genetic variation was assumed for the trait of interest across different generations (Hopkins and James 1978). However, it is well realized that the additive genetic variance is decreased after several generations of intense selection. Thus, the actual genetic gain is likely less than the expected genetic gain. In other words, the outcomes of these breeding schemes are likely affected by the intensity of selection as well as the relative size of the nucleus population to the size of whole population. The aim of current study was to investigate the effect of relative nucleus size at three levels of 5, 10 and 15 percent and the effect of selection intensity in males and females at three levels of high (i.e. selection proportion in male and female candidates were 1 and 20 percent, respectively), moderate (i.e. selection proportion in male and female candidates were 5 and 50 percent, respectively) and weak (i.e. selection proportion in male and female candidates were 10 and 80 percent, respectively) on the amount of biasness of predicted genetic gain due to ignoring the effect of selection on genetic variance. An open nucleus breeding scheme was deterministically simulated using data from Lori Bakhtiari sheep breed, consisting a nucleus herd of 1005 ewes and a base herd of 4019 ewes (Vatankhah 2005). Birth weight was the breeding goal trait and selection was carried out using one individual performance record. The generation was assumed to be overlapped and three and six age groups were considered for males and females, respectively. The age of parents at first lambing was 2 years and 0.94 yearling lamb was produced per ewe. One ram was mated to 33 ewes. The additive genetic variance for breeding goal trait was 0.11 and its heritability was set to 0.30. For a given size of the nucleus and a constant rate of transferring ewes from base population to nucleus (x), there was an optimum rate of migration of nucleus rams into the base population (w), that maximized the expected genetic gain and minimized the genetic lag between nucleus and base populations, with or without accounting for the effect of selection on the genetic variance. By increasing the relative size of the nucleus, from 5 to 15 percent of whole population, the biasness of the predicted genetic gain was increased from 11.84 to 16.67 percent. At a given rate of x, the bias of genetic gain prediction which originated from ignoring the effect of selection, varied nonlinearly as the rate of w increased and had a minimum value at the optimal value of w. At a particular rate of w, increasing the rate of x, was associated with higher rate of bias. The rate of bias increased from 12.2 to 16.54 percent, as the intensity of selection increased. The reason could be the markedly reduction in the genetic variance of considered trait due to selection at high selection intensities. In open nucleus schemes, the amount of bias changed from 14.18 to 17.72, as a consequence of increasing the intensity of selection. Across all levels of selection intensity in open nucleus programs, the lowest bias was observed at the rate of 0.75 for w. Evaluation of joint effect of relative nucleus size and intensity of selection, showed that at high selection intensity and relative nucleus sizes higher than 10 percent, the amount of bias was not likely to be influenced by nucleus size. Ignoring the effect of selection on genetic variance could result in a biased prediction of genetic gain in the nucleus breeding schemes. However, the optimal ram transfer rate from nucleus to base population was independent from the effect of selection intensity. The lowest bias was observed for the scheme with optimum transfer rate. Results of the current study revealed that at weak selection intensity, the effect of selection could be ignored and the breeding program could be optimized for ram transfer rate from nucleus to the base populations. However, at high selection intensities, the ignorance of this effect might result in wrong conclusions.

As the resources are limited, improving efficiency of sheep farming is of high importance in Iran. In the present study, the technical efficiency of Moghani sheep flocks was investigated using the method of data envelopment analysis, considering constant (CRS) or variable (VRS) returns to scale. Data of year 2015 on inputs for the amount of concentrate, forage and labor as well as outputs including the amount of meat, milk, wool and fertilizer were collected from 214 Moghani sheep flocks through interviews and questionnaires. Data analysis was performed using Deap 2.1 software. The average technical efficiencies with CRS and VRS were 0.978 and 0.977, respectively, showing high efficiency in studied flocks. With CRS and VRS, there were 14 and 25 flocks being technically efficient, respectively, and could be introduced as reference flocks to inefficient ones. The results showed that with VRS, some reduction in flock size, labor, forage, concentrate, rangelands roughages and health costs as 2.99, 2.99, 2.63, 2.79, 2.73 and 6.41 percent, respectively, would let inefficient flocks to become efficient, while maintaining the same level of previous production. The estimates of return to scale showed that most of Moghani sheep flocks had an increasing return to scale, and are able to benefit from scale-based savings and lowered cost per output unit.

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.

The objective of the present study was to evaluate the effects of inbreeding on growth traits in Guilan province sheep. Traits included average daily gain from birth to 3 months (ADG1), average daily gain from birth to 6 months (ADG2), average daily gain from 3 months to 6 months (ADG3) and corresponding Kleiber ratios (KR1, KR2 and KR3, respectively). Data and pedigree information used in this study were collected during 1994 to 2011 by the Agriculture Organization of Guilan Province. The effects of inbreeding rate on the traits investigated (for a change of 1% in inbreeding) were analyzed using the Reg procedure of SAS for type of birth, lamb’s sex and all lambs. The effects of inbreeding on all traits except ADG1 were positive. The regression coefficients of ADG1, ADG2 and KR2 were estimated to be -0.138, 0.101 and 0.0053 g, respectively (P

An open nucleus breeding scheme consisting a nucleus herd of 500 ewes and a commercial herd of 4500 ewes was simulated deterministically using the information of the population of Lori Bakhtiari sheep to investigate the effect of heritability and nucleus size on the bias of estimates for genetic gain. The objective function was 9 months body weight and the selection was based on own record. Different values for heritability in nucleus and commercial herd and also different nucleus sizes were considered and the expected genetic gain was estimated by ignoring or accounting for the selection effect and from the ratio of these two estimates the amount of bias of estimates for genetic gain was obtained. The results showed that when the heritability of the nucleus and the commercial herd were equal, the highest bias (18%) occurred. Increasing the heritability in nucleus and commercial herd from 0.1 to 0.9 showed the amount of bias was directly related to heritability and ranged from 10 to 36 %. When the heritability in nucleus was fixed at a given value, and the heritability in commercial herd changed, the rate of bias altered, but only by 10 % indicating the amount of bias is not so sensitive to the heritability in the commercial herd. Results related to the changes in nucleus size indicated that the amount of bias changed between 10 to 20 %; therefore, effect of this factor on the bias is negligible. In general, the most important factor on the bias of genetic gain estimates, due to ignoring the effect of selection, is the heritability.

Along with increase in genetic progress, maintaining genetic diversity in any population is very important to adapt with the economic and environmental changes in the future and ensure long-term response to selection for traits that are very important. Intensive use of a few breeding animals, where the selection intensity is high, could result in greater rates of inbreeding in the population. Therefore, a small number of seedstock, with a strong family relationship, is responsible for the maintenance of almost the whole genetic pool in the population. This is an aspect of great influence in the genealogical analysis of a population structure, because of its effect on the probability of genes lost between generations and the consequent reduction in genetic variability. The unavoidable mating of related animals in closed populations leads to accumulation of inbreeding and decreased genetic diversity. Measurement of the effect of inbreeding on these traits is important in order to estimate the magnitude of changes associated with increases in inbreeding although direct selection for lower maintenance requirements is difficult. Some populations may show a very pronounced effect of increased inbreeding for a trait, whereas others may not display much of an effect. The rate of inbreeding needs to be limited to maintain diversity at an acceptable level, so that genetic variation will ensure that future animals can respond to changes in the environment and to selection. Without genetic variation, animals cannot adapt to these changes. Commonly, negative inbreeding effects, or inbreeding depression, are thought to most frequently occur because of an increase in frequencies of recessive alleles that adversely affect the traits of interest. The increased frequency of recessive alleles leads to a larger number of individuals that are homozygous for the recessive alleles, whereas in non-inbred populations, the recessive allele would more frequently be masked by an advantageous dominant allele. Kleiber ratio (KR) allows us to identify efficient animals. This ratio, defined as growth rate/ metabolic weight (body weight0.75), was suggested for measuring growth efficiency. One of the most important breeds of Iranian sheep is Mehraban sheep which is reared in Hamedan province. This breed is adapted to harsh climate and rocky environments in the western regions of Iran. The Mehraban is a fat-tailed carpet wool sheep with light brown, cream or grey color, dark face and neck and primarily used for meat production. The objective of this study was to evaluate the inbreeding effects on daily weight gain and Kleiber ratio in Mehraban sheep.
Data and pedigree information used in this research were collected from 1994 to 2011 in Jihad Agriculture Organization of Hamedan province. Studied traits were average daily gains from birth to weaning (ADGa), average daily gain from weaning to 6 months (ADGb), average daily gain from weaning to 9 months (ADGc), average daily gain from weaning to yearling (ADGd) and corresponding Kleiber ratios (KRa, KRb, KRc and KRd). All animals were grouped into three classes according to their inbreeding coefficients: the first class included non-inbred animals (F=0) and the second and third classes included inbred animals (0 Significant regression coefficients ADGa, KRa, ADGb, KRb, ADGd and KRd on inbreeding of all lambs were observed for 1% increase of inbreeding. According to the birth type, the regression coefficient of all traits except KRc on inbreeding of single-born lambs and ADGa and KRa on inbreeding of twin-born lambs was significant for a 1%. increase in inbreeding. According to lamb sex, the regression coefficient of all traits except ADGd and ADGc on inbreeding of male lambs and ADGc and KRd on inbreeding inbreeding of female lambs was significant for a 1% increase in inbreeding.
The results showed both significant and non-significant effects of inbreeding on daily weight gain and kleiber ratio traits. The results of this study showed that inbreeding level of over 90% of animals was between 0 and 50%. These results indicate multiple use of a small number of sires in the herd, also the lack of use of mating programs designed for prevent high levels of inbreeding in Mehraban sheep.
The results showed positive and significant effects of inbreeding on average daily gains and Kleiber ratios in Mehraban sheep.

The objective of this research was to study the heterogeneity of variance components for protein yield from the first three lactations of Iranian Holstein cows which collected from 1983 to 2014 by the Animal Breeding Center and Promotion of Animal Products of Iran. Data set were 141670, 115395 and 82529 records in the first, second and third lactations. Data were classified into three categories of Mediteranean, Dry desert and Humid using Domarten method. The heterogeneity of variances was studied using the Bartlett’s test. The results of Bartlett’s test before data transformation in the first three lactations were significant (P

In this research data of Iranian native buffaloes which were collected by the animal breeding center of Iran in 20 years from 1993 to 2013 were used. Data for first, second and third parities included 4339, 4439 and 4445 test-day records, respectively, which were distributed in 298 herds. The GLM procedure of SAS was used for determining the environmental effects affecting on milk protein percentage. The fixed effects of herd-test day, year-season and days in milk and age at calving as covariate were fitted in the model of analysis. Genetic parameters were estimated for milk protein percentage on different days in milk using single trait random regression model of the Wombat software. Heritability estimates for this trait in the first, second and third parities ranged from 0.005 to 0.14, 0.03 to 0.7 and 0.005 to 0.24, respectively. The highest heritability for milk protein percentage in the first, second and third parities were estimated in 300th, 300th and 5th days in milk as 0.14, 0.7 and 0.24, respectively. The means of genetic correlation in the first, second and third parities were estimated to be 0.09, 0.98 and 0.95, respectively. The heritability estimates of milk protein percentage were relatively high in this study. Therefore, optimal milk protein percentage can be obtained by selection in Iranian buffaloes.

In most animal models applied for genetic evaluation of animals, it is assumed that residual and genetic variances are homogeneous in different environments and genotypes, but in situations where data are obtained from different environments or at different times, this assumption may be unrealistic and inaccurate. However, numerous studies have reported heterogeneous genetic, residual, and phenotypic variances for production traits based on different factors such as geographical region, production level and herd. Since the selection decisions in animal breeding rely on estimated breeding values, ignoring the fact that variances are heterogeneous has consequences, including inappropriate selection, loss of expected genetic progress and decreased efficiency of breeding programs. The aim of this study was to investigate the homogeneity or heterogeneity of variances for milk and fat yield in different climatic regions of Iran as well as the impact of various methods of data transformation on reducing or possible elimination of variance heterogeneity and its effects on changing the rank of the top animals in the population of Holstein cows in Iran.
In this study milk and fat yield records which were collected from 1983 to 2014 by the Animal Breeding Center and Promotion of Animal Products of Iran were used. Records of milk and fat yield were adjusted for 305-d lactation and two times milking. Data were grouped based on the Domarten method and Bartlett’s test was used for studying the heterogeneity of variances. The transformation methods of Logarithmic, Square root and Box-Cox were applied for removing heterogeneity. Estimated breeding values (EBVs) for animals were estimated with adjusted and unadjusted data and the Spearman's rank correlations between EBVs were computed to assess the re-ranking of best sires and cows under different percentages of selection.
Results of Bartlett’s test were significant for milk and fat yields in the first three lactations which indicated the heterogeneity of variances. Applying Box-Cox data transformation resulted in homogenous variances milk and fat yields in the first and third lactations, respectively, and square root and logarithmic methods did not remove completely the heterogeneity, but they reduced partly non uniformity. Heritability of milk yield and fat yield after data transformation varied from 0.114 to 0.223 and 0.161 to 0.193, respectively, which were slightly higher than that raw data. Re-ranking of common animals in the top 1% of dams was more than 5% of top sires. Box-Cox transformation method resulted in homogenous variances and excluded top 5% and 2% of sires and dams for milk yield and fat yield from the routine list, respectively.
Based on the current results, it can be concluded that variance components for milk and fat yields according to different geographic areas in Holstein cow population is heterogeneous and heterogeneity of variance affects on genetic evaluation and re-ranking of top sires and dams. Box-Cox transformation method is more appropriate than other methods because of removing heterogeneity of variances as well as having the highest rank correlation and minimal changes in the rank of animals.

In this study genetic gain from a progeny testing program corresponding to the characteristics of Holstein population in Iran and an equivalent genomic selection program in terms of number of needed male and female parents were compared and the effect of number young bull on the genetic gain in these two programs was evaluated. Selection objective included the milk production. Genetic gain for milk production from four path selection was estimated using gene flow method over a 150-year horizon. The results showed that the progeny testing and genomic selection differed, in addition to selection accuracy, by selection intensity and generation interval. The annual genetic gain from progeny testing was 114.7 and from genomic selection was 173.7kg. The results of the change the number of young bulls from 50 to 300 showed genetic gains varied between 106.11 to 117.53 kg by progeny testing and between 160.95 to 185.38 kg in genomic selection. In both programs the genetic gain was more sensitive to the change in the number of young bull when it was less than 100.In general this study showed that the genetic gain obtained from genomic selection could be higher than that of progeny testing by more than 50% because of shorter generation interval. But this superiority was affected by the number of young bull and would reach to minimum level at 75 young bulls.

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.

Ascites syndrome is a metabolic disorder in fast growing broilers. Due to high mortality, the poultry industry carries economic detriment. Ascites related traits have high heritability which shows impressibility of genetic factors. Therefore, genetic selection against ascites susceptibility is possible. The aim of the current study was to evaluate consequences of alternative selection indices to reduce ascites susceptibility using deterministic simulation. The traits investigated were partial pressure of oxygen in venous blood, bicarbonate, oxygen saturation in venous blood and ratio of right to total ventricular weight. In addition, the consequences of having information on the underlying genes (MAS) were identified. Alternative selection strategies were compared based on the selection response for body weight and ascites susceptibility, accuracy of selection as well as the rate of inbreeding. The results showed that by including blood gas parameters as indicator traits to ascites, reduced genetic response for BW5 based on indices number 1, 2, 3, 4, 5, 6 were 20, 23, 69, 16.8, 18.8 and 15.7 percent of genetic response for BW5 based on single trait selection, respectively. The results of schemes comprising QTL information of ascites susceptibility showed that ascites susceptibility can be reduced appropriately with considering different values of genetic variance due to QTL. This reduction was lower by including QTL information and was about 2.8 percent for BW5 in which QTL explains 50% of the genetic variance of ascites syndrome. The profitability of MAS was depended on economic analysis of animal breeding programs.

This study was conducted to investigate the homogeneity of variance components for milk yield (MY) and to assess the effects of different data transformation methods on the ranking of elite animals in Iranian Holstein cows. Data sets included 245192 records for 1st lactation period, 202078 records for 2nd lactation and 147253 records for 3rd lactation collected from 1983 to 2014 by the Animal Breeding Center and promotion of Animal Products of Iran. Records were classified into three different groups based on herd-year size. Four different data transformation methods including Logarithmic, Arc sin, Square root and Box-Cox were applied and the data were tested for heterogeneity of variance before and after using Bartlett’s test. The results indicated the heterogeneity of variance in all three groups (P

Economic values for production, reproduction, growth and functional traits in crossbred and Holstein cow production systems in Guilan province were estimated using a total of 16 herds consisting in average 12 and 30 cow, respectively, and a bio-economic model. Economic values were calculated in two production systems for 12 traits, classifying into four categories of production, reproduction, growth and survival. Economic value of each trait was estimated as the amount of change in the annual profit of production system by one unit increase in mean of the considered trait while the means of other traits were hold unchanged. Economic values, relative to the economic value for productive lifetime, for milk yield, fat yield, protein yield, age at first calving, calving interval, pre-weaning daily gain, post-weaning daily gain, birth weight, mature live weight, pre-weaning survival rate and post-weaning survival rate were, respectively 3.7, 0.003, -0.01, -7.26, -32.6, -4.35, -23.4, -46.55, -0.78, 4.26 and 68.68 for crossbred production system, and were 0.92, 0.001, -0.002, -6.72, -20.64, -1.10, -6.10, -11.82, 0.21, 30.49 and 25.29, for Holstein production system. The results showed, although the importance of some traits in two production systems were different, which was a reflection of overall difference in two production systems, the breeding objective of two population should be very close together, considering high similarity of economic values of traits

Using a deterministic model,the changes in generation interval forpathway of dam of dams as a result of sex sorted semenutilization in heifersunder various reproduction conditions was investigated. Three sex sorted semen using strategies were considered.They included continuous usage of sex sorted semen over all inseminations (CS); the use of sex sorted semen atonly first and the second inseminations (S2), and the use of sexed sorted semen atonly the first insemination (S1). Various reproduction situations were described by conception probability associated to using sex sorted semen and conventional one. The results indicated that generation interval by various strategies and reproduction situations varied from 4.0506 to 4.2063 years. Utilization of sex sorted semen by S1 strategy led to shorter generation interval in all situations of reproduction. The shortest range of variation in generation interval under various conditions was due to using S1 strategy (0.08 years) and the highest one was attributed to CS strategy (0.15 years). In general, generation interval for the pathway of dam of dams resulting from using sex sorted semen was longer than that of conventional semen, but was negligible (up to 0.1 years). In the case of necessity for sex sorted semen, it would be recommendable to apply S1 strategy.

Body weight traits prior to weaning are of special importance in sheep breeding programs.

In this study genetic parameters for pre-weaning growth traits in Shall sheep were estimated using data on birth weight (BW), weaning weight (WW) and average daily gain (ADG) from birth to weaning, collected during 1994 to 2009 in Qazvin province. The data belonged to four herds and included 1,992 records for BW, 1,584 records for WW and 1,568 records for ADG.

Six different models were used to estimate the genetic parameters. The most appropriate model was determined for each trait using likelihood ratio test.

The estimated direct heritability for BW, WW and ADG were 0.34, 0.48 and 0.21, respectively. Genetic correlations between traits were positive and medium to high. The phenotypic correlations were lower than the corresponding genetic correlations.

Due to high heritabilities estimated of birth and weaning weights and also high genetic correlation between these traits, direct selection for genetic improvement of these traits will be effective.

The genetic characterization of local breeds of sheep is of paramount importance, not only for conservation purposes but also for the definition of breeding objectives and breeding programmes. When records are nonexistent and breeds are not well defined in the field, information could be obtained from research station information where pedigree and performance records have been kept. Early growth of animals is mostly dependent on the animal’s genetic merit for growth and maternal genetic and permanent environmental effects. Hence, both the direct and maternal genetic effects should be taken into account in a selection program to achieve optimum genetic progress. Studies on different sheep breeds have indicated that both direct and maternal genetic effects are essential for lamb growth. The efficiency of any sheep production enterprises can be improved through considering economically important traits such as litter size, body weight of lamb and quantity and quality of wool in the breeding objective. Growth is an economically important trait of farm animals which can be interpreted mathematically. It is a time (age) dependent change expressed in the weight or size of organ, composition of tissue/organ, size or number of cells and in live weight. Growth rate is related to rate of maturing and mature weight and these traits have been suggested to have association with lifetime productivity parameters in animals. Slow growth rate causes low market weight and has been identified as one of the limiting factors affecting the profitability of any production system. Selection of animals based on their predicted breeding values and accurate estimation of genetic parameters for economically important traits are required for designing optimal breeding strategies for farm animals. The Kleiber ratio has been suggested to be a useful indicator of growth efficiency and an indirect selection criterion for feed conversion under field conditions. The Guilan sheep is a fat-tailed breed of domestic sheep in Iran, numbering some 400, 000 animals in the north of the country, and distributed in the northern and western parts of Guilan Province in the mountains between Assalem, Khalkhal, Oshkourat, and Deilaman. This breed can also be found in some areas of Guilan-Zanjan border. Mean adult live weight in this breed is 35 kg (77 lbs) for rams and 31 kg (67 lbs) for ewes. The coat color for this breed is yellowish-white to pure white, but brown patches are found on the head, face and at the bottom of the legs. This breed is valued mainly due to its small size, meat, and ability to live in mountainous areas with rain-fed foothills and foothill steppes with 1300 mm (51 inches) rain. The objective of the present study was to estimate genetic parameters for average daily gain from birth to 3 (ADGa), 6-month of age (ADGb), average daily gain from 3 to 6-month of age (ADGc) and corresponding Kleiber ratios (KRa، KRb و KRc) in Guilan province sheep. Data and pedigree information used in this study were collected during years 1994 to 2011 by the Agriculture Organization of Guilan Province, Iran. The GLM procedure of SAS was used for determining the fixed effects which had significant influence on the under study traits. Level of significance for the inclusion of effects into the model of analysis was declared at P.

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.

The objective of the present study was to estimate genetic parameters and genetic and phenotypic trends of body weight traits from birth to yearling ages Mehraban sheep. Traits included were birth weight, weaning weight, 6- month weight, 9-month weight and yearling weight. The data included 10278 lambing records and pedigree information used in this research were collected at the Breeding Station of Mehraban sheep (Hamedan provice, Iran) during 1994-2011. Genetic parameters were estimated using restricted maximum likelihood procedure of the Wombat program and the SAS program was used for editing and analysising data. Direct heritabilities for BW, WW, 6MW, 9MW and YW were estimated as 0.25±0.04, 0.46±0.05, 0.59±0.08, 0.57±0.08 and 0.11±0.08, respectively. The heritability estimates of these traits suggested the most suitable trait for conducting direct selection were WW for pre-weaning and 6MW for post-weaning period. Direct genetic correlations between birth weight with other body weights ranged from -0.02 between BW and 9MW to 0.95 between 9MW and YW. Direct genetic trend was significant only for birth weight (P<0.01). Phenotypic trends were significant for all traits (P<0.01).