In many organisms, large offspring have improved fitness over small offspring, and thus their size is under strong selection. However, due to a trade-off between offspring size and number, females producing larger offspring necessarily must produce fewer unless the total amount of reproductive effort is unlimited. Because differential gene expression among environments may affect genetic covari...

If the poultry industry hopes to continue to flourish, the identification of potential quantitative trait loci (QTL) for production-related traits must be pursued This remains true despite the sequencing of the chicken genome. In view of this need, a scan of the chicken genome using 72 microsatellite markers was carried out on a meat-type x egg-type resource population measured for production a...

A study was undertaken to evaluate the reproductive performance in two plumage colour variant strains of quail, viz; Brown, White Breasted and a dark Cinnamon Brown (commercial) strain. A total of 694 straight run active chicks were obtained in three hatches at weekly intervals from the three strains. Sex was determined at six weeks of age and female progenies were separated and data on reprodu...

Invasive alien species might benefit from phenotypic plasticity by being able to (i) maintain fitness in stressful environments ('robust'), (ii) increase fitness in favourable environments ('opportunistic'), or (iii) combine both abilities ('robust and opportunistic'). Here, we applied this framework, for the first time, to an animal, the invasive slug, Arion lusitanicus, and tested (i) whether...

BACKGROUND Chicks of virulent brood parasitic birds eliminate their nestmates and avoid costly competition for foster parental care. Yet, efforts to evict nest contents by the blind and naked common cuckoo Cuculus canorus hatchling are counterintuitive as both adult parasites and large older cuckoo chicks appear to be better suited to tossing the eggs and young of the foster parents. METHODOL...

in the present study the allelic polymorphisms of gh, ghr and tgfβ3 genes and its association with egg production traits were investigated. blood samples randomly were collected from breeder hens of mazandaran native fowls breeding station and transported to the laboratory in cold chain condition. dna was extracted using modified salting out method and the desired loci were amplified by specifi...

The first objective of this study on broiler breeders was to investigate the genetic basis of variability in hatchability over age using a longitudinal model. Weekly percentage hatch of fertile and hatch of set eggs were available for 23,250 dams mated to 3,106 sires of the same age between the 28th and 54th week of life. Hatch of set was very highly correlated with fertility and showed a simil...

With the Weihenstephan funnel nest box, 12 laying hen flocks were tested for their individual laying performance, egg quality, and nesting behavior in a noncage environment. During the whole observation period of 8 yr, a transponder-based data recording system was continuously improved and resulted in a recording accuracy of 97%. At peak production, heritabilities for the number of eggs laid ar...

The aim of this study was to investigate the genetic and phenotypic correlations of egg quality traits in Khazak chicken. Albumen height (AH), albumen weight (AW), eggshell color (ESC), yolk color (YC), eggshell index, long length of egg (ELL), short length of egg (ESL), eggshell weight (ESW), egg weight (EW), Haugh units, and yolk weight (YW) were measured in 201 eggs collected 6 d sequentiall...