scholarly journals Histomorphometric Bone Properties of Sexually Immature and Mature White Leghorn Hens with Evaluation of Fluorochrome Injection on Egg Production Traits

1993 ◽  
Vol 72 (8) ◽  
pp. 1537-1547 ◽  
Author(s):  
H.A. HUDSON ◽  
W.M. BRITTON ◽  
G.N. ROWLAND ◽  
R.J. BUHR
Keyword(s):  
Egg Production ◽  
Production Traits ◽  
White Leghorn ◽  
Bone Properties

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

Genetic studies on egg production traits in IWN and IWP strains of White Leghorn chicken

2018 ◽  
Vol 53 (3) ◽  
pp. 247
Author(s):  
Snehal D. Patil ◽  
F.P. Savaliya ◽  
A.B. Patel ◽  
H.I. Paleja ◽  
R.S. Joshi ◽  
...  
Keyword(s):  
Egg Production ◽  
Production Traits ◽  
White Leghorn ◽  
Genetic Studies ◽  
White Leghorn Chicken

scholarly journals Estimates of genetic parameters, and cluster and principal components analyses of breeding values related to egg production traits in a White Leghorn population

2011 ◽  
Vol 90 (10) ◽  
pp. 2174-2188 ◽  
Author(s):  
R.P. Savegnago ◽  
S.L. Caetano ◽  
S.B. Ramos ◽  
G.B. Nascimento ◽  
G.S. Schmidt ◽  
...  
Keyword(s):  
Principal Components ◽  
Egg Production ◽  
Genetic Parameters ◽  
Production Traits ◽  
White Leghorn ◽  
Breeding Values

scholarly journals Genetic effects of aging on egg production traits in the first laying cycle of White Leghorn strains and strain crosses

2000 ◽  
Vol 79 (3) ◽  
pp. 296-304 ◽  
Author(s):  
M.C. Ledur ◽  
R.W. Fairfull ◽  
I. McMillan ◽  
L. Asseltine
Keyword(s):  
Egg Production ◽  
Genetic Effects ◽  
Production Traits ◽  
White Leghorn ◽  
Effects Of Aging

Sire × hatching season interaction in egg production traits within flocks of domestic fowl

1979 ◽  
Vol 30 (5) ◽  
pp. 991
Author(s):  
BH Yoo ◽  
BL Sheldon
Keyword(s):  
Domestic Fowl ◽  
Variance Component ◽  
Egg Production ◽  
Production Traits ◽  
White Leghorn ◽  
Egg Weight ◽  
Sib Families ◽  
Selection For ◽  
Efficiency Of Selection ◽  
Season Interaction

The extent of sire x hatching season interaction in egg production characters has been studied in White Leghorn, Australorp and Synthetic flocks in which half-sib families bred from the same sires were mated largely to the same dams for spring and autumn hatchings. Interaction appeared to be more important in White Leghorn and Synthetic than in Australorp. The estimate of variance component for interaction was not consistent among the three flocks, and it was important only in certain flocks for different characters: age at first egg, part-annual hen-housed production (PHP), and egg weight at 34 and 62 (EWL) weeks of age in Synthetic; and annual survivors' production and egg specific gravity at 62 weeks of age (SGL) in White Leghorn. Comparison of within-season and across-seasons heritabilities showed that the former could be on average more than 45% higher than the latter in PHP, EWL, SGL and annual hen-housed production. As the estimates of the genetic correlation coefficient between seasons tend to be below 1.0 for many characters in White Leghorn and Synthetic, the sire x hatching season interaction may need to be taken into account and investigated further to improve the efficiency of selection for egg production.

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