scholarly journals DOMINANCE AND EPISTASIS IN HETEROSIS OF WHITE LEGHORN STRAIN CROSSES

1987 ◽  
Vol 67 (3) ◽  
pp. 663-680 ◽  
Author(s):  
R. W. FAIRFULL ◽  
R. S. GOWE ◽  
J. NAGAI
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Egg Production ◽  
Significant Contribution ◽  
Production Traits ◽  
White Leghorn ◽  
Cross Combination ◽  
Commercial Strain ◽  
Better Than

Four unrelated pure strains of White Leghorns including a grandparent strain from industry and 12 two-strain, 24 three-strain, 24 four-strain and 12 F2 strain crosses produced contemporaneously were used to examine the role of dominance and epistasis in heterosis. A control strain and a commercial strain were also included. For egg weight, the heterosis observed closely approximated that expected due to dominance alone. For sexual maturity and body weight, dominance was the major component of heterosis, but epistasis made a significant contribution — additive by additive (A × A) genetic effects for sexual maturity and 140-d body weight, and parental epistasis for mature body weight. Both dominance and epistasis played a significant role in heterosis for egg production traits. A × A, dominance by dominance (D × D) and additive by dominance (A × D) epistasis were all important for hen-housed egg production and hen-housed egg yield. For hen-day rate of egg production, A × A epistasis was significant only early in the laying year (to 273 d), A × D and D × D were significant to 385 d and in the full year (to 497 d); however, none (A × A, A × D and D × D) was significant near the end of lay (386–497 d). Overall heterosis estimates for full year egg production measured as hen-housed egg production to 497 d or hen-day rate from housing to 497 d clearly showed that on average two-strain crosses were superior to three-strain crosses which were superior to four-strain crosses which in turn exceeded the F2 crosses. Nevertheless, several three-strain crosses had performance for egg production that was equal to or better than the two-strain cross with the highest egg production. Thus, in commerce, where the level of egg production is of great economic importance, the testing and use of a specific three-way cross combination will usually result in a better commercial product. Key words: Heterosis, egg production genetics, epistasis, stocking rate, strain cross, White Leghorn

scholarly journals Crossing effect for improving egg production traits in chickens involving local and commercial strains

2020 ◽  
Vol 13 (3) ◽  
pp. 407-412
Author(s):  
Mostafa Ahmed Soliman ◽  
Mohamed Hassan Khalil ◽  
Karim El-Sabrout ◽  
Mostafa Kamel Shebl
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Egg Production ◽  
Local Strain ◽  
Egg Mass ◽  
Reciprocal Effects ◽  
Production Traits ◽  
Egg Weight ◽  
Commercial Strain ◽  
Egg Traits

Aim: This study aimed to contribute to the productivity improvement of the local chickens by enhancing their egg production traits using a crossbreeding program between Alexandria (local strain) and Lohmann White (commercial strain). Materials and Methods: One thousand two-hundred and eighty-five 4-week-old chicks from two strains: Alexandria local strain (AA) and Lohmann White commercial strain (LL) and their reciprocal crosses obtained from 16 males and 160 females, were used to produce four genetic groups (AA, LL, AL, and LA). Differences among genotypes, direct additive, heterosis, and reciprocal effects were investigated regarding the following traits: Body weight at 4 and 8 weeks and at the age of sexual maturity, age at sexual maturity, egg production, average egg weight, and egg mass during the first 90 days of laying. Results: Statistically significant effects of the genotypes were observed on traits studied. Analysis of direct additive effects showed that AA was superior as a sire strain for improving body weight at early age. For egg traits (age at sexual maturity, egg production, average egg weight, and egg mass), LL was better as a sire strain to improve these traits. Significant positive heterosis percentages were observed for body weight. The crosses (AL and reciprocal) were significantly superior in egg traits (egg production, average egg weight, and egg mass) compared to the local strain. The cross (LA) laid significantly earlier than the local strain. Analysis of reciprocal effects cleared that the local strain could be used as a strain of dam to improve body weight and egg traits. Conclusion: Crossing improved egg production, egg weight, and egg mass in hybrids compared to the local strain.

scholarly journals GENETIC AND PHENOTYPIC ASSOCIATIONS OF JUVENILE BODY WEIGHTS AND EGG PRODUCTION TRAITS IN TWO STRAINS OF RHODE ISLAND CHICKENS

2021 ◽  
Vol 18 ◽  
pp. 66-70
Author(s):  
O. O. ONI ◽  
B. Y. ABUBAKAR ◽  
S. O. OGUNDIPE
Keyword(s):  
Body Weight ◽  
Rhode Island ◽  
Sexual Maturity ◽  
Egg Production ◽  
Genetic Parameters ◽  
Laying Hens ◽  
Genetic Correlations ◽  
Selection Criterion ◽  
Production Traits ◽  
Body Weights

Data on body weight at 16 (WT16); 20 (WT20) weeks of age and at sexual maturity (WTSM) weight of first egg (WT1st), age at sexual maturity (ASM) and 120-d egg production (EN)  were used to estimate genetic parameters in 636 hens of two strains of Rhode Island chikens. There were significant (P.01) differences between  the two strains for all traits except for WTSM.The heritability estimates obtained ranged from 0.05 to 0.41 and 0.04 to 0.30 for strains 1 and 2 respectively. The genetic correlations obtained for the various traits were medium to high for the two strains. The phenotypic correlations were generally low but followed the same trend. The results indicate that selected stocks of the two strains would show improvements in egg production and age   at sexual maturity if juvenile body weight (WT20) is employed as a selection criterion at housing for laying hens.

scholarly journals Canonical correlation analysis for studying the relationship between egg production traits and body weight, egg weight and age at sexual maturity in layers

2011 ◽  
Vol 50 (No. 4) ◽  
pp. 163-168 ◽  
Author(s):  
Y. Akbaş ◽  
Ç. Takma
Keyword(s):  
Body Weight ◽  
Correlation Analysis ◽  
Canonical Correlation Analysis ◽  
Canonical Correlation ◽  
Sexual Maturity ◽  
Egg Production ◽  
Production Traits ◽  
Egg Weight ◽  
Canonical Correlations ◽  
The Relationship

In this study, canonical correlation analysis was applied to layer data to estimate the relationships of egg production with age at sexual maturity, body weight and egg weight. For this purpose, it was designed to evaluate the relationship between two sets of variables of laying hens: egg numbers at three different periods as the first set of variables (Y) and age at sexual maturity, body weight, egg weight as the second set of variables (X) by using canonical correlation analysis. Estimated canonical correlations between the first and the second pair of canonical variates were significant (P < 0.01). Canonical weights and loadings from canonical correlation analysis indicated that age at sexual maturity had the largest contribution as compared with body weight and egg weight to variation of the number of egg productions at three different periods.  

scholarly journals Synthesis of stocks and phenotypic effects of dwarf and bantam sex-linked major genes in egg-type chickens

1997 ◽  
Vol 20 (3) ◽  
pp. 371-376
Author(s):  
Randolfo William Silvestre Custódio
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Egg Production ◽  
Egg Laying ◽  
White Leghorn ◽  
Major Genes ◽  
Adult Body ◽  
Adult Body Weight ◽  
The Difference

The present study describes the production of stocks segregating dwarf (dw), bantam (dwB) and normal (dw+) alleles, as well as the characters, shank length, adult body weight, age at sexual maturity and egg production. Heterozygous K dw+/k dwB sires were mated to normal (dw+) dams to produce stock D6.a, and mated to dwB females to produce stock D6.b. Stock D4.a came from mating F1 heterozygous dwB dw sires to dwarf Leghorns. In a third series of matings, 7/8 Sebright and 1/8 dw-Leghorn dwB dw sires were crossed to three groups of dams of different genotypes. The progeny of the normal (dw+), dwarf (dw), and bantam (dwB) dams were designated as stocks D4.b, D4.c and D4.d, respectively. The dw+ dams were White Leghorn strain cross females. The difference between the rate of laying of normal (69.7%) and their bantam sisters (68.6%) was not statistically significant when the average 32-week body weight of the dw+ sisters was 1,897 g. However, when the 32-week body weight of the normal daughters from the same sires and smaller dams was around 1,646 g, the difference between the rate of laying of the normal (78.1%) and their bantam sisters (75.9%) was significant (P < 0.05). The dwB gene may have a similar but smaller effect on the rate of egg laying than its dwarf allele. The difference between sexual maturity of normal and bantam daughters of either the largest or the smallest dams was not statistically significant, even though the smallest dwB pullets were in average 2.9 days older at first egg. The use of shank length combined with adult body weight allowed a precise discrimination between bantams and dwarfs

scholarly journals Mathematical Modelling of Egg Production Curves of Shikabrown Parents

2020 ◽  
Vol 44 (1) ◽  
pp. 61-75
Author(s):  
A. Ahmadu ◽  
M. Kabir ◽  
A. O. Iyiola-Tunji ◽  
O. M. Akinsola ◽  
H. Igbadun
Keyword(s):  
Body Weight ◽  
Linear Model ◽  
Egg Production ◽  
Research Programme ◽  
Coefficient Of Determination ◽  
Production Traits ◽  
Egg Weight ◽  
Mean Values ◽  
Egg Number ◽  
Better Than

This study was conducted to evaluate egg production curves of Shikabrown parents, using  mathematical models. A total of 200 birds: 100 from each of the two strains of Shikabrown®  parents (sire and dam) lines at the Breeding Unit of Poultry Research Programme, National Animal Production Research Institute (NAPRI) were used for the study. The birds were obtained from the selected lines (sire and dam) and were denoted as Strain A and Strain B, respectively. Body weight (BWT), age at sexual maturity (ASM), egg number (EGGNO), and egg weight (EWT) were examined. Four non-linear models (Logistic, Richard, Gompertz, and Exponential) and a linear model were used to predict the efficiency of weekly bodyweight and egg production traits. The adequacies of the models were fitted using R Package, version 3.0.3. High coefficients of determination for BWT (R2 = 0.84 - 0.93) were recorded in the models for both Strains. Strain A had higher R2 (0.93) for BWT in Richard, Gompertz and Exponential models while Strain B recorded (R2 = 0.89) in Logistic, Richard and Gomprtz models. High coefficient of determination was obtained in a reproductive trait; egg number; in which almost all the models gave (R2 = 0.70). Exponential model recorded a higher R2 (0.93) for EGGNO in strain A. EWT in strain A recorded higher R2 (0.96) coefficient of determination across the four nonlinear models except linear model with (R2 = 0.95) for egg weight. Significant differences (P<0.05) were observed in the birds' performance for BWT and EWT, with strain B having a higher BWT (1.59±0.01) and Strain A having a higher EWT (48.75±0.17). Similarly, age of birds in lay had a concomitant significant differences (P<0.05) in their BWT as well as their EWT. The birds performed better for BWT and EWT in week 26 and 27 for both Strains. It was concluded that Strain significantly (P<0.05) had effect on BWT and EWT of Shikabrown® parent with Stain B performing better than Strain A in the former trait and strain A better than strain B in the latter trait. R2 identified differences between Strains in predicting egg production traits. Strain B was adjudged good and profitable because the Strain had the highest mean values in body weight and egg number and it is being recommended as one of the lines for future improvement of Shikabrown® .

Single crossing between White Leghorn and Australorp

1958 ◽  
Vol 9 (6) ◽  
pp. 842 ◽  
Author(s):  
JA Morris ◽  
F Skaller
Keyword(s):  
Body Weight ◽  
Artificial Insemination ◽  
Sexual Maturity ◽  
Egg Production ◽  
The Body ◽  
White Leghorn ◽  
Reciprocal Crosses ◽  
Related Data ◽  
Single Crossing ◽  
White Leghorns

Egg production and related data are presented for 1520 pullets resulting from nine generations of single crossing between White Leghorns and Australorps. Both types of reciprocal crosses were consistently superior to the better of the parental breeds (White Leghorn) in hatchability, chick viability, and egg production. This superiority became still more apparent when pure and crossbred half-sisters were compared. Crossbreeding was not effective in improving the viability of adult birds or the body weight, the latter remaining intermediate between that of the two pure breeds. The number of days required to reach sexual maturity was decreased as a result of crossbreeding. The crossbreds showed less variation in egg production and included in their sample a much smaller percentage of extremely low-producing pullets. A comparison between the two types of crossbreds shoved differences in individual years, but when viewed over the whole period of the experiment the only consistent differences were the superior hatchability and higher fertility, under artificial insemination conditions, when the White Leghorn served as the dam. There were no significant differences in production characters between the two types of crossbreds when housed on deep litter.

PERFORMANCE OF LAYING HENS FED DIETS CONTAINING GUMS DERIVED FROM TOWER RAPESEED

1977 ◽  
Vol 57 (3) ◽  
pp. 479-483 ◽  
Author(s):  
S. LEESON ◽  
J. D. SUMMERS ◽  
S. J. SLINGER
Keyword(s):  
Body Weight ◽  
Soybean Meal ◽  
Egg Production ◽  
Detrimental Effect ◽  
Laying Hens ◽  
Dietary Treatment ◽  
Rapeseed Meal ◽  
White Leghorn ◽  
Commercial Strain ◽  
Eggshell Quality

An experiment was conducted to investigate whether rapeseed gums have any detrimental effect on the performance of laying hens. White leghorn pullets of a commercial strain were fed all-mash diets in which the major source of protein was provided by either soybean meal, rapeseed meal, rapeseed meal + 1.5% rapeseed gums, soybean meal + 1.5% rapeseed gums or soybean meal + 1.5% soybean gums. Each diet was offered to four replicate groups of 12 birds during ten 28-day experimental periods. Dietary treatment had no significant [Formula: see text] effect on feed intake or egg production. Birds fed diets containing rapeseed meal produced significantly [Formula: see text] smaller eggs than those birds receiving soybean meal with no added rapeseed gums. Eggshell quality as measured by shell deformation was significantly [Formula: see text] improved when birds were fed rapeseed meal + rapeseed gums or soybean meal + soybean gums, compared to those birds fed either rapeseed meal, or soybean meal with added rapeseed gums. Rapeseed gums had no significant [Formula: see text] effect on body weight or the incidence of liver hematoma. It is concluded that no deleterious effects accrue from feeding laying birds diets containing rapeseed meal to which has been added 1.5% gums, and that the addition of such gums provides rapeseed processors with a useful pollution-free method for their disposal.

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