Journal of Crop Production and Processing

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In order to study the genetic and environmental variability of morphological and phenological characteristics and also to gain a better understanding of the morphological basis of yield variation in soybean, an experiment was conducted at Research Farm, College of Agric., Isfahan University of Technology, in 1996. The experiment was arranged in three augmented designs with 285 lines and 5 control varieties. There were highly significant differences among genotypes for all the characteristics studied. The phenotypic coefficients of variability were greater than the genotypic ones for all the traits although the differences for most of them were small. The highest phenotypic and genotypic coefficients of variation, in order of magnitude, were obtained for number of pods per plant, days to flowering, plant height, height of the lowest pod, and number of lateral branches. Heritability estimates and the percent of genetic improvement for these traits and seed weight were high but for seed yield per plant were low. The lowest coefficients of variability were related to number of seeds per pod and days to germination. The results of stepwise regression analysis indicated that the maximum variation in seed yield could be attributed to the number of pods per plant, number of seeds per pod, and 100-seed weight. Factor analysis in addition to emphasizing the importance of yield components, resulted in four factors which determined 97.34% of yield variation. These factors which were indicators of physiological sink and source, with respect to the traits contained, were named as photosynthetic sink, plant architecture, fixed capital, and weight, respectively. In general, it was concluded that in order to improve soybean cultivars, selection should be in favor of plants with stronger structure, higher number of leaves, nods and pods per plant, and higher seed weights.

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Data of 1200 male and female chicks from 90 sires were used to estimate the heritabilities as well as genetic and phenotypic correlations of body measurements and carcass characteristics in three genetic groups, namely, crosses of native chickens with an exotic breed (group A), native chickens which were selected for two generations on the basis of 8th week body weight (group B) and a native control group (group C).

The effects of genetic group, sex and system (litter vs. cage) on body measurements (shank and breast traits) and carcass characteristics were studied. Data of body measurements were collected at 6th week of age, and carcass traits were recorded at slaughter time at 10th week of age (except breast angle which was recorded at 8th week).

All carcass traits and body measurements except shank were significantly affected by genetic groups (P<0.05). Sex and system of rearing did not have any significant effect on body measurements and carcass traits. Estimated heritabilities for body measurements and carcass traits showed a wide range. Breast and shank measurements had the lowest and those related to abdominal fat had the highest heritabilities. Phenotypic correlations for all of the body measurements were lower than genetic correlations among these traits. Genetic correlations between body measurements and carcass characteristics were mostly significant

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In order to estimate the heritability of morphological characters of worker honey bee and honey yield, 30 queen-mothers were selected randomly from the apiary of Research Center of Animal Science and Natural Resources in Isfahan Province. From each queen-mother, five queen-daughters were reared and introduced to equalize colonies after natural mating of queens. Summer honey yield was measured, while fall honey production was calculated from area of sealed honey combs. The total honey was calculated by adding summer honey production to fall honey production. Morphological characters were measured under a stereo-dissecting microscope fitted with a calibrated micrometer reticle according to Ruttners method (1985).

 Heritabilities were estimated by intraclass correlation method. Heritabilities of summer, fall and total yearly honey yields were estimated to be 0.64, 0.51 and 0.30, respectively. Estimates of heritability of morphological characters for probscis length, tibia length, femur length, metatarsus length, metatarsus width, forewing length, forewing width, cubital index, hindwing length and number of hamuli were 0.64±0.08, 0.45±0.07, 0.50±0.07, 0.47±0.07, 0.33±0.06, 0.42±0.06, 0.89±0.10, 0.5±0.07, 0.94±0.10 and 0.45±0.07, respectively. It could be concluded that in order to increase honey yield in either season (summer or fall), selection must be based on the amount of honey yield in the corresponding season. Thus, heritabilities of forewing and hindwing lengths were high selection according to these morphological characters would, therefore, change the size of these characters.

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Diallel crosses of six breeding inbred lines of corn (Zea mays L.) were used to estimate combining abilities, heterosis and some other genetic parameters for yield and some of its components. Parents, 15 F1 crosses and 4 filler genotypes, were evaluated in a 5×5 simple lattice design. For all the traits studied, except seed length, the efficiency of lattice design was less than one. Therefore, data were analysed as a randomized complete block and after eliminating the filler genotypes, Grriffing’s method 2 with mixed B model was used in the genetic analyses.

General and specific combining ability (GCA and SCA) mean squares were statistically significant for all traits studied. The ratios of GCA to SCA mean squares were greater than one for all traits, except for the number of seed rows per ear, indicating the importance of non-additive gene effects in their genetic control. Low heritability estimates and degrees of dominance lower than one were further evidence of the presence of non additive gene effects for all the traits studied, except for the number of seed rows per ear. Therefore, production of single cross hybrids in order to take advantage of non-additive gene effects is of prime importance for grain yield, number of seeds per ear row, l00-seed weight, seed length, ear length, and comb percentage. For genetic improvement of number of seed rows per ear, selection methods for parental lines will be more efficient. In the hybrids studied, number of seed per ear row and l00-seed weight played a more important role in the observed variations in yield. In general, hybrids 4×5 and 5×6 with high SCA for number of seed per ear row, l00-seed weight and grain yield were considered favorable for the conditions of this study.

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The efficiency of cross-breeding programs mainly depends on the choice of the progenitors and the knowledge on the transmission of traits that breeder wants to improve. In the present study heritability rate of 65 traits related to different parts of vegetative, reproductive, nut and kernel in 12 populations (320 progenies) derived from controlled crosses of 13 local and foreign almond genotypes and cultivars were assessed. Results obtained from parents evaluation showed that ‘Shahrood-12’ was the latest blooming while ‘15/5’ and ‘A’genotypes were the earliest blooming than the other parents. Among the 12 studied populations, in total 46 superior progenies were chosen in terms of heritability of evaluated traits with emphasis on flowering time. Heritability of some important traits such as flowering time, leafing date and bearing habit were obtained as 0.70, 0.80 and 0.75 respectively. Also fitted regression line of these traits was significant at 1% probability level. Close relationship between flowering time and leafing date were obtained in evaluated progenies. Heritability of some nut traits such as weight, length, width, softness and hardness and shell thickness were obtained to be 0.77, 0.60, 0.69, 0.73 and 0.60 respectively and the fitted regression lines to these traits were significant at the 1% probability level. Heritability of traits related to almond kernel such as length, width, weight, shape, double kernel percentage and shriveling were estimated 0.75, 0.79, 0.76, 0.96, 0.55 and 0.54, respectively.

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To determine gene action and heritability of grain yield related traits in rice, six rice varieties including Hashemi, Vandana, Kadous, Hassani, Shahpasand and IR36 were crossed in a diallel design in 2010. The parents and seeds of F1 generation (36 genotypes) were grown in a completely randomized block design with three replications at the Research Field of the Rice Research Institute of Iran-Rasht in 2011. In this experiment, the yield related traits including grain yield, number of panicles per plant, number of spikelet’s per panicle, 1000-grain weight, plant height, panicle length and flag leaf area were measured in each experimental unit. Evaluation of the gene action based on the Hayman graphical method indicated that 1000-grain weight was controlled by partial dominance effect and the other attributes were controlled by complete dominance to over-dominance effects. Broad-sense heritability varied from 54.91% to 99.84% for flag leaf area and plant height, respectively and narrow-sense heritability ranged from 26.04% to 88.68% for panicle length and 1000-grain weight, respectively. Results of this research showed that the additive gene effect can be used to improve several traits including 1000-grain weight, but utilizing the heterosis phenomenon and hybrid production is recommended to improve the remaining traits in the studied population.

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Identification of easily measured physiological traits contributing to yield under specified environmental conditions would benefit genotypic selection for grain sorghum. A field experiment was conducted to determine broad-sense heritability and expected genetic advance, and to examine the relationships of grain yield with 11 physiological traits related to developmental periods, vegetative growth, growth rate, grain filling rate, and partitioning to the grain.

Sorghum genotypes exhibited significant differences for all traits, except for grain yield. Broad-sense heritability estimates ranged from a low of 49.6 (for grain filling rate per unit area) to a high of 99.4 (for days to maturity). Expected genetic advance ranged between 9.2% (for days to transition of vegetative to reproductive phase, days to maturity and number of leaves) and 39.8% (for grain filling rate per grain unit). Generally, grain yield gave a significant negative correlation with physiological traits related to development and vegetative growth. But, this correlation was positive and significant for growth rate, grain filling rate, and harvest index. Grain yield was low in its coefficient of genetic variation and expected genetic advance. It is, therefore, concluded that indirect selection for grain yield via growth rate, grain filling rate per unit area and harvest index is efficient. Results suggest that use of easily measured physiological traits in sorghum breeding is possible.

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This experiment was conducted to estimate genetic parameters of some of the important traits of silkworm in two populations, namely, Japanese and Chinese lines in Iranian Silkworm Rearing Co-Natanz. Based on single pair mating method, 9 male moths mated with 9 female moths and then raised under standard environmental conditions. Performance of 30 progenies of each pair was recorded.

Heritability coefficients (parental full-sib method) of single cocoon weight (CW), shell weight (SW), pupal weight (PW) and shell ratio (SR) were estimated to be 0.209±0.123, 0.228±0.129, 0.174±0.109 and 0.044±0.042 in the Japanese race and 0.196±0.1l8, 0.234±0.132, 0.159±0.103 and 0.00, in the Chinese race, respectively. Genetic and phenotypic correlation between CW & SW were 0.645 & 0.957, CW & PW, 0.962 & 0.982, CW & SR -0.351 & 0.123, SW & PW, 0.496 & 0.871, SW & SR, 0.265 & 0.457, PW & SR, -0.446 & 0.169, respectively. Selection, based on heritability coefficients of single cocoon weight and shell weight, can be applied successfully to genetic-gain in this trait. Based on correlation coefficients between traits, selection for shell weight can be applied successfully to improve other traits such as single cocoon weight and shell ratio.

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The current research was carried out to investigate grain yield and components and their genetic diversity and heritability of some important agronomic traits, in 19 chickpea genotypes, based on a randomized complete block design with 3 replications in Research Field of Bu-Ali Sina University, Hamadan, Iran in 2011-2012 growing seasons. The ANOVA results showed that, there were highly significant differences (p < 0.01) among genotypes for the SPAD number, number of sub-branch per plant, pod number per plant, 100-kernel weight, grain yield, biological yield, and harvest index. The mean comparisons results indicated that the genotypes 14, 12, 4 and 19 (with 234.7, 240, 250.3 and 259.4 kilogram of grain yield per ha, respectively) and the genotypes 18, 8, 15, and 6 (with 151.01, 167.6, 167.8 and 189 kilogram of grain yield per ha, respectively) had the maximum and minimum economic yield, respectively. According to phonotypical correlation results, there were positive and significant (p < 0.01) correlations between grain yield and pod number per plant (0.623**), plant height (0.432**), harvest index (0.425**) and biomass (0.349**). Step-wise regression indicated that the pod number per plant, harvest index, biomass, number of sub-branch per plant, and plant height were the most effective traits on economic yield and they explained 84.68 percent of the variation in economic yield. Furthermore, harvest index and seed number per plant had the maximum and minimum heritability, respectively, indicating that they could be hired as sources of variation for improving the grain yield and selecting superior genotypes.

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The objective of the present research was to investigate the effect of salinity stress on sodium, potassium and calcium concentrations, and Na⁺/K⁺ and Na⁺/Ca²⁺ ratios at seedling stage in an advanced back cross (BC₂F₆) rice population. The population was derived from crossing between Hashemi, an Iranian cultivar, and IR67418-110-32222 (IR-22) from IRRI. The ANOVA indicated that the effects of genotypes, salinity stress and interaction between stress and genotype were significant for all the traits, which is suggestive of high level of genetic variation, salinity effect on traits and different response of the genotypes to salinity levels. The salinity stress markedly decreased the K⁺ concentration in the shoot. However the shoot Na⁺ and Ca²⁺ concentration and Na⁺/K⁺ and Na⁺/Ca²⁺ ratios were significantly increased in saline environment. The population characteristics mean value were found to be between of parents values and it often shifted to recurrent parent (Hashemi) value in both stress and non stress conditions. It shows that Hashemi variety gene’s leave more influences on the expression of the traits in the population. Transgressive segregation was observed for all the studied traits in the population lines. Genetic and phenotypic correlations among the studied traits showed the same trend. The highest correlation coefficients were related to Na⁺ concentration and Na⁺/K⁺ (r_g= 0.89**) in non stress condition. The high heritability levels of the traits provide selection possibility for salinity tolerance in the population based on these traits. According to the present findings, it is possible to candidate some lines (such as line number 139) as salt tolerant at the seedling stage.

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This research was conducted to evaluate genetic variation and estimate genetic parameters of forage yield and related traits in Dactylis glomerata. Twenty five half sib families derived from poly cross of 25 parental genotypes were evaluated under two moisture environments (normal and drought conditions) according to a randomized complete block design in Research Farm of Isfahan University of Technology. Results indicated that there are significant statistical differences and high genetic variation among the families for most of the studied traits. Drought stress significantly affected all forage related traits (except for leaf to stem ratio), leading to decreases in a majority of them. Mean of forage yield was decreased by 53.48 percent due to drought stress. Genotypic coefficient of variation under non-stress condition ranged from 1.78 to 45.1 and under drought condition ranged from 1.7 to 30.4, indicating a high genetic variation in this germplasm. The highest narrow sense heritability was related to crown diameter in both moisture environments. Narrow sense heritability for dry forage yield was 52% at non-stress and 45% at stress conditions. Based on dry forage yield, genotypes 2, 5, 8, 13 and 15 showed a higher general combining ability in both moisture conditions and, therefore, are potent to be used for developing synthetic varieties.

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In order to study seed yield components and agronomic traits in some F₃ families of flax (Linum usitatissimum L.), this experiment was conducted in 2014 at the Research Farm of Isfahan University of Technology, Isfahan, Iran. In this experiment, 50 families of F₃ generation derived from different crosses were evaluated in a randomized complete block design with two replications. The results showed that there were significant differences among the families for all yield components, seed yield per plant and seed yield per plot.  The means of seed yield per plot for the families ranged from 622 (family of 32) to 2212 kg/ha (family of 37).The range of days to maturity, plant height and seed yield per plant in families was 82 to 97 days, 38 to 71.3 cm and 1.27 to 3.71 g, respectively.  The coefficient of genetic variation for most of the studied traits were slightly smaller or very close to those of phenotypic ones, indicating that most of the observed variation for these traits were due to genetic factors, and thus a moderate to relatively high broad-sense heritability (45.7 to 86.83%) was observed for those traits. The highest and lowest genetic variations were observed for seed yield per plot and days to flowering, respectively. Cluster analysis based on the agronomic traits separated the families into 4 distinct groups, in which the 2^nd and 4^th groups had the highest mean of seed yield components and, thus seed yield per plot. Generally, the results showed that there was high genetic variation for the studied traits including seed yield and its components and selection can be effective to improve these traits. 

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Yield is a quantitative trait and improving grain yield through direct selection is time-consuming. Indirect selection consisting of selection indices is more promising. A field experiment was conducted during 1999-2000 growing season in two experimental locations (Kooshkak and Badjgah) of College of Agriculture, Shiraz University, Shiraz. Thirteen corn hybrids were used in a randomized complete block design with three replications in each location. Thirty-five traits were measured in five developmental stages (stem elongation, tasseling, blister, hard dough and physiological maturity) and combined analysis of variance and covariance were conducted. Finally, 12 traits were selected for constructing selection indices via path analysis. Two optimum selection indices were used in this experiment. In both selection indices, different combinations of traits applied as linear function (multivariate linear model) and coefficients of traits in combinations were calculated. The coefficient of indices were obtained from: b=P^-1Ga, where b is the vector of index coefficients, P^-1 is the inverse of phenotypical variance and covariance matrix, G is the matrix of genotypical variance and covariance and a is the column vector of traits heritability. In the first index, heritability of traits with the same sign was used as economic values. Selection index including grain yield and net assimilation rate in the second stage (NAR₂) was the best. In the second index, the sign of genotypic correlation with yield was given to economic values. Finally, selection index including grain yield and NAR₂ was the best, too. In both selection indices, correlation of selection indices with genotypic value was equal to 1. This was 14% higher than the first index including yield alone. In both selection indices, physiological indices including net assimilation, crop growth, and relative growth rates were the most important traits comprising the best selection indices.

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This study was done to investigate and compare fruit yield, yield components, morphological traits and fruit quality of greenhouse tomato genotypes in order to use them as selection criteria. Progenies of 49 crosses of greenhouse tomato together with their 13 parents were evaluated using Randomized Complete Block Design with three replications. The highest amount of fruit yield was observed in the  progenies of the crosses 20, 25 and 46. On the other hand, the progenies of the  crosses 17 and 18, which showed the highest amount of fruit quality, also had a suitable fruit yield. The highest number of fruits was observed in the progenies of the crosses 18, 16 and 19. In order to selecte the most effective traits as the selection criteria, broad and narrow sense heritabilities were estimated under two growing seasons by uniparental-perogeny, biparental-perogeny regression, and parental-perogeny correlation. The amount of broad sense heritability ranged from 45 to 92% in the  first season and from 43 to 80% in the second one. Therefore, the traits including the total fruit yield, fruit weight, pericarp thickness, Brix, and PH were suggested for selecting the best genotypes, because of the higher level of heritability in these traits. Higher amounts of narrow-sense heritability in number of fruit per cluster and internode length suggested that these traits are appropriate as selection criteria. But the results showed that selection criteria varied in different environmental conditions.
 
 

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To evaluate heritability, phenotypic and genotypic correlation coefficients, phenotypic and genotypic variances as well as relationships between some of the grain quality traits, an investigation was conducted in a randomized complete block design replicated three times in 2001, using four durum wheat genotypes PI40100, Dipper-6, Oste/Gata, Shova and their F₂ and F₃ progenies derived from their crosses. Grain quality characteristics including seed hardiness, protein content, SDS sedimentation volume and gluten content were evaluated. The results indicated that wet gluten content and dry gluten content had the highest coefficient of variation. Statistical analysis showed a significant difference between genotypes for all traits with the exception of SDS sedimentation volume. Dry gluten content had the highest heritability (90.4%) while SDS sedimentation volume had the lowest heritability (48.6%). Results of correlation analysis indicated that seed hardiness correlated significantly with protein content, SDS sedimentation and dry gluten content. Protein content had a positive correlation with wet and dry gluten content. Since dry gluten content showed a high correlation with protein content (quantity) and seed hardiness had a high correlation with SDS sedimentation volume, hence these two traits can be used as the selection criteria for improving quality of protein in durum wheat.

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The Genetic basis of grain yield and related characteristics were studied by a generation mean analysis in five crosses of winter wheat (Triticum aestivum L.). “Roshan”, “Mahdavi”, “Inia”, “Atila” and “Goscoyin” cultivars along with their F₁, F₂, BC₁ and BC₂ populations were evaluated by a split-plot design with crosses as the whole plot in a randomized complete block design with two replications and generations were applied as the subplots. Analysis of variance revealed significant differences among generations for studied characteristics including the grain yield per plant, the number of spikelet per plant, the number of spikelet per spike and grain weight per spike. For the majority of traits and crosses, F/DH^1/2 was less than one, indicating that the sign and magnitude of gene actions were different. Estimates of broadsense and narrow sense heritabilities were low for the grain yield per plant compared with other traits, rating from 28.5% to 58.6% and 24% to 48,5% for the five crosses, respectively. Genetic components of generation means were calculated by fitting different models and choosing the best model indicated that the impact of additive, dominance and epistasis genetic components in controlling the traits depend on the cross and the trait under study.

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Diallel analysis was used to estimate the combining ability, gene action, gene number, heritabilties and other genetic parameters of a set of wheat genotypes. For this purpose, nine parents and their 36 crosses were evaluated for 9 traits in a randomized complete block design with three replications in 1996. The analysis of variance revealed significant differences among all genotypes for all traits. Estimates of general and specific combining ability mean squares based on Griffing’s Method 2 indicated the importance of additive and non additive effects in the expression of all traits. Alvand and Roshan cultivars for grain yield per plant, Alvand for grain number per main spike and main spike weight, and Alvand and Alamoot for 1000 grain weight were the best combiners, thus use of them is beneficial for these traits. Based on the estimates of average degree of dominance and results of graphical analysis, the gene action for grain number and spikeletes per main spike were partial dominance, while for grain yield per plant, biological yield, plant height, harvest index and 1000 grain weight, overdominance gene actions were observed. Moreover, genotypic correlation coefficients of grain yield per plant with grain number per main spike, 1000 grain weight, grain weight per main spike and main spike weight were positive and significant.

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The precision of evaluation for agronomic traits is very important in the field experiments to determine the genetic potential of genotypes or effect of treatments. The precision of the experiment mainly depends on the number of replications. The objective of this study was to investigate the effect of number of replications on the precision of genotype evaluation, estimation of variance components and on the heritability for agronomic traits in flax (Linum usitatissimum L.). In this study, nine genotypes of flax were evaluated for different traits, using a randomized complete block design with 8 replications. The results showed that the reduction of error variance due to increasing the number of replications mainly depended upon the type of the trait. For evaluation and estimation of heritability for number of seedlings /m² and plant height, 3 and 2 replications were suitable, respectively. The results also showed that using more than 2 replications had no considerable effect on the prescision of evaluation, nor on the increase of heritability for days to maturity. Based upon the results, for evaluation of the number of capsules per plant, 3 or 4, and for seeds per capsules, 4 replications can be suggested. For seed yield that is the most important economic trait in flax, a relatively constant estimated mean and broad-sense heritability were obtained with 4 to 8 replicationshowever, using 2 or 3 replications over-estimated the mean of the triat (approximately 11%) and under-estimated the broad-sense heritability about 27% and 10%, respectively. With 2 replications, the estimated mean and broad-sense heritability for seed yield were 2017.6 kg/ha and 72.1%, respectively. Gain from selection for seed yield based on evaluation of genotypes with 2, 3 and 8 replications was estimated as 787, 796 and 798 kg/ha, respectively. Therefore, it seems that 2 replications can also be used for seed yield evaluation of genotypes in breeding programs of flax.

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A total of 25,471 Iranian Holstein heifers distributed in 523 herds of 20 provinces were used to estimate heritability, genetic and phenotypic associations between a number of traits related to the production and reproduction performance. The Animal Breeding Centre of Iran collected the records studied in this research between 1991 and 2001. The traits associated with production were 305-day, 2x adjusted milk, fat yields and fat percentage and the traits associated with reproduction were age at first calving, number of services per conception, gestation period, calving interval as well as dry days as a separate trait. The heritability estimates were 0.31, 0.23, 0.31, 0.14, 0.03, 0.05, 0.10 and 0.01 for 305-day, 2x milk, fat yields, fat percentage, age at first calving, dry days, calving interval, gestation period and the number of services per conception, respectively. Milk yield was genetically correlated with age at the first calving (-0.14), dry days (-0.31), calving interval (0.54), gestation period (0.01) and the number of insemination per conception (0.38). Fat yield had negative genetic correlations with age at first calving (-0.16), dry days (-0.23) while it was positively correlated with calving interval (0.44), gestation period (0.11) and the number of insemination per conception (0.20). Age at the first calving, dry days and gestation period had a positive genetic correlation with fat percenateg (0.03, 0.15 and 0.09 respectively) while calving interval and the number of insemination per conception were negatively correlated with fat percentage (-0.21 and -0.25 respectively).