Showing 4 results for Crosses
Mohammad Ali Edriss, Javad Pourreza, Saeid Ansari,
Volume 3, Issue 1 (4-1999)
Abstract
This experiment was conducted to study egg production traits in a flock of native fowl from Isfahan region and their crosses with three improved exotic breeds. Sexual maturity (SM), weight of the first egg (WFE), number of eggs (EP), egg weight (EW), feed intake (FI), and feed conversion ratio (FCR) were recorded individually during laying period up to 52 weeks of age. There were no significant differences (P < 0.05) in WFE between the four groups, but the difference between the four genetic groups was highly significant (P < 0.01) for SM, EP, EW, FI and FCR. During laying period, pooled coefficients of heritability (sire component) for SM, WFE, EP, EW, FI and FCR were estimated to be 0.24 ± 0.10, 0.03 ± 0.08, 0.41 ± 0.12, 0.48 ± 0.12, 0.13 ± 0.09 and 0.18 ± 0.09, respectively. In combined analysis, part record egg production (SM to 34 weeks of age) was positively correlated (genetically and phenotypically) with EP up to 52 weeks of age (rg = 0.74 ± 0.11, rp = 0.71). The values suggested that there is a relatively appropriate relationship in the combined groups analysis. In addition, EP up to 34 weeks of age was negatively correlated with FCR during the same period (rg = -0.92 ± 0.53, rp = -0.81).The estimated genetic and phenotypic correlation in this study suggested that selection based on part record egg production can not only be used successfully to improve EP during full record, but may also cause a better laying performance during laying period.
Heshmatollah Khosravinia, Mohammad Ali Edriss, Javad Pourreza, Saeid Ansari,
Volume 3, Issue 1 (4-1999)
Abstract
To estimate heritability, and genetic and phenotypic relationships and also to study the effect of sex and rearing environment on body weight, weight gain, feed consumption and feed conversion coefficient, the data from 1200 pedigreed male and female chickens from three genetic groups including 90 sires were used. The included genetic groups were crosses of native chickens and 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 control group of native chickens (group C). All the chicks were reared up to four weeks of age on the ground in separated pens according to their sire groups. In order to calculate feed conversion coefficient, 498 chicks were placed in individual cages during four to ten weeks of age. The results showed that the cross group (A) compared to the other two groups had a higher body weight at 2, 3, 6, 8 and 10 weeks of age. Weight gain, feed conversion coefficient and consumption at periods of 4-6, 6-8, 8-10 and 4-10 weeks were also higher in the cross group. Genetic groups B and C, in spite of better performance of group B for most of the traits, did not have any significant differences for the compared traits. Estimated heritabilities on the basis of sire variance component showed that these traits were medium to highly heritable. Estimated heritabilities for feed consumption at different ages ranged from 0.15 to 0.44 which at any age was lower than that estimated for feed conversion coefficient. Genetic and phenotypic correlations between growth traits were positive and, in most of the cases, high. Correlations between nutritional traits at different ages were variable.
M.a. Edriss, H. Khosravinia, J. Pourreza,
Volume 4, Issue 1 (4-2000)
Abstract
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
H. Mohammadi, M.khodambashi Emami, A. Rezai,
Volume 11, Issue 40 (7-2007)
Abstract
Half diallel crosses of nine Iranian wheat cultivars were used to estimate the general and specific combining ability effects and other genetic parameters related to yield and its components. Parents with F2 generations were evaluated at Research Farm, College of Agriculture, University of Shahrekord, in a randomized complete block design with 3 replications. Partitioning of genotypes mean squares to GCA and SCA mean squares based on Griffing’s method 2 and mixed model indicated high significant differences among cultivars in their GCA values for all traits. There were significant differences among crosses in their SCA values for all traits except for flag leaf length, main spike length, plant height and grain yield per plant. The high ratio of GCA to SCA mean squares implied the importance of additive gene effects in the appearance of flag leaf length , main spike length, plant height and grain yield per plant. For flag leaf width, grain number per main spike and peduncle length , the contributions of additive gene effects and for peduncle weight, the contributions of non- additive gene effects were higher. According to the estimates of average degree of dominance, the gene actions for flag leaf length, flag leaf width, plant height, grain yield per plant, main spike length, peduncle length and peduncle weight were partial dominance. The GCA effects indicated that Sefid – Aliabad cultivar was the suitable general combiner for flag leaf length , flag leaf width, plant height , grain yield per plant , main spike length and peduncle length.
