Development of a chick in the Egg

Very good information about development of a chick in the Egg.

SIR THANKS

Incubator temperature affects the percentage of male-to-female chicks.more females at lower temperature; more males at higher temperature. The adjustment is just a half a degree Fahrenheit up or down.

Dear sirs,

I have gone through all comments and answers. I also had seen such comments from a scientist who have been involved in crocodile breeding where they take up some hatching program for production of crocodiles for which there was some funding by forest dept of the state through central assistance. It was projected also by regulating temperature in the incubator the sex ratio changes. 15 years back I wrote to the scientist of a academic university who try to say this from her findings in the project. I could not agree to such conception or results . It is because we are in poultry science and such views do not hold scientifically a good message. Sex of any living animal and birds are decided through sex-chromosomes not by temp or humidity or turning options available in incubators. Performances are decided by the poly genes of autosomes and sex-chromosomes give the attributes of sex-linked genes. So let us have productive discussion as per science not by physical incubation environments. There are reports and studies on the shape of Hatching eggs leading to sex determination but it had never supported truth till date. There is always a feeling with human brain to select a sex in all species to his or her advantage but sorry not possible unless embryos grow to some extent. So let us conclude the temp, humidity, turning ,ventilation of incubators will assist hatching of egg and always safe with good technicians.

Quality of hatch and chick quality depend on incubator handling . Layer and broiler hatchery if hatch is 90% then probability in terms of population size it would be close to 1:1 sex ratio. Vent method of sexing is very popular at day old sexing and sex-linked genes are also used to separate sex through sex-linked phenotype traits.

Let us read more on this area and it will remove confusions. Dr M Rath, consultant in poultry science.

An individual's genotype at one or more loci can control whether it develops testes or ovaries. Species that display this mechanism are said to have genotypic sex determination, or GSD. Species with GSD may or may not have distinct sex chromosomes (ZZ males and ZW females or XY males and XX females). A frequent alternative to GSD is environmentally triggered polyphenism (i.e., a single individual can develop testes or ovaries depending upon environmental conditions). Such species are said to have environmental sex determination, or ESD. Various environmental factors, including photoperiod, social environment, and temperature, influence sex determination across the animal kingdom. The effect of incubation temperature on sex is only described in some Reptiles (snakes have GSD mechanism, turtles exhibite TSD, but both the mechanisms are documented in lizards). I have found no evidence about TSD pathway in avian species, however, according to some valid scientific findings, birds have evolutionary deriven from certain reptile ancestors. Considering these evolutionary affinities between birds and reptiles, TSD pathway may be active in birds. It is worth noting that inovo injection of some antiaromatases induces higher phenotypic male: female ratios in both avian and reptile species. Finally, TSD pathway needs more detailed studies to be confirmed in birds.

What I liked most in this article were the photographs which were very clear and difficult to capture from actual embryos. Good job.. Frankly, as a suggestion, the schedule of development of the embryo narrated in the article could have been presented differently rather than just mention cold facts.which will be interesting to a layman rather than someone who works in a hatchery because every hatchery will have displayed a chart showing the day to day development of the embryo. What i would have liked the respected author to do is, along with the details to include some fresh insights on the critical factors which the hatchery man needs to remember in his incubation management.at different stages of development.
Regarding the question of sex determination of chicks, over the years I have done some trials on the influence of temperature on the sex of chicks and have not found any convincing results. I wish someone finds a way to determine the sex of chicks because this will be a great break through especially in the layer production. Imagine the savings by getting all the layer chicks which hatch to be females and all the broilers coming out as males.
.

Let us wait and see when we can produce the desired sex through environmental manipulation or biotechnology technique . Now it has no scope.If any hatch would show wide variation in sex ratio then there must be droop in hatching percentage possible. Thanks for initiating such topic. Author has given data through review of literature -embryological information through this forum for chicken eggs. HEgg starts with germinal disc(blastoderm) and end as chick through the gestation period specific to chicken. Late hatch and early hatch are common reports due to incubator operation impact and other factors but not sex of chick.

I agree that sex determination is not at all affected by temperature variations in the incubation process but rather the sex chromosomes. the resulting sex ratios derived from the manipulation of the incubator temperature is more the effect of preferential embryonic mortalitiy on either male or female embryos. At any rate, the article and pictures are very well presented and very informative. However, with regards the incubation process, it is better to take embryonic development in hourly timeframes rather than lump 24 hour segments, hence we discuss incubator and hatching performances based on the number of hours it takes for an egg to become a chick and how wide the hatch "window' is.

This article is very useful to me because now I am working in poultry industry in technical department.
This article is easy to understand.

Beautifully explained. Thanks farhan. I was planing for a long time to start a broiler shed but so farI have seen one must hire a specialist to stary this business as its too risky .If u have any frnd who wants a job and is willing to work with me in my new business do let me know . I'm leaving my number if u have any frnd who is in lahore or any person who is specialist in poultry and want to do job at my farm plz let me know 03454222226.and if u r willing thts fine too.

Mr Muzafar Hayat Tarar,
Brazil is highly advanced in poultry production and consult a commercial poultry organization at your country who can support you 100% for production of chick at your hatchery- proposed by you for construction. But before start you need to finalize what is your objective - it is commercial production of chicks for sale to other farmer, or you have your own broiler farm for meat production. You will get good number of specialists or poultry persons who know production program.
Survey the market first if you do like to egg production farm or broiler production farm accordingly you may proceed. Production is ok but marketing of produce egg, meet, spent hen, manure etc with your own retail out lets are points to be considered.
Good luck to have such business and it is excellent project and once you are exposed you can get good confidence for good earning. dr m rath

Sir kindly give ans to this question...
Why is there more double yolk eggs in early production stage???......plz elaborate it in such  way so I could understand easily..........thnx.

This is my answer to Dr. Anjum's question about double yolk eggs in the early stages of lay.
First of all this happens both in the layer as well as the broiler strains, but the incidence in Broiler strains which genetecially have higher body weights is higher.
As to the reasons, there are two factors which I am aware of and have actually seen happening:
1. Some of the individuals in a flock which are hyper sensitive to light stimulation tend to poly ovulate and the result is two yolks within the egg. This happens even if the lighting programme is normal. It's just that some birds happen to be reacting to light stimulation rather abnormally. This is the reason why I do not believe that the solution to cut down the incidence of double yolk eggs is to cut down lighting.The incidence will gradually come down as the stimulation pattern within the bird settles down to normal within a few weeks.
2. Birds which have abnormally high body weights have a trendency to lay eggs with two yolks.

Is there any Hormonal role in bird in laying Double yolk egg ?

Tell me the mechanism of regression of POF....Thnx