Chickens have their own battle of the sexes, and scientists have discovered a secret strategy used by hens to control who fertilizes their eggs: After mating, hens can eject the sperm of less desirable, low-status roosters.
Sperm from a rooster is stored in the hen's oviduct for up to 10 days, so after just a single successful mating many fertilized eggs can be laid.
The ability to store sperm in the female reproductive tract is frequently found in a variety of animals including insects, fish, amphibians, reptiles, birds, and mammals [1,2,3].
When a rooster mates a hen, his injected semen is stored in numerous sperm storage tubules (SSTs) located in the area where the hen's uterus joins the vagina. That is, provided the hen likes the rooster. If she doesn't, she can squirt out the semen to avoid hatching his offspring.
A hen to rooster transformation is most definitely possible no matter how impossible it may seem. This occurrence usually occurs due to a genetic condition where the chickens only functioning ovary is damaged. The non-functioning ovary can then start to develop into a structure known as an avo-testis.
If a sexually active rooster is placed into a flock of hens, fertile eggs can be produced by the second day after introducing the rooster. If mating occurs within a short period, the next egg yolk released by the hen's body can be fertilized.
A hen does not know if her eggs are fertilised or not. In fact (much like a human) a rooster can be infertile, so a hen's eggs might not be fertilised even if she is in a flock with a rooster. Many modern breeds and commercial hybrid hens will do nothing with their eggs other than lay them and walk away.
See how a hen makes an egg. A rooster is needed, however, if your goal is to produce chicks. Roosters needs to mate with a hen two or three times a week in order for the hen to lay fertile eggs. You can then incubate the eggs to hatch out chicks.
PARTS OF THE MALE CHICKEN REPRODUCTIVE SYSTEM
In the male chicken, as with other birds, the testes produce sperm, and then the sperm travels through a vas deferens to the cloaca. Figure 2 shows the main components of the reproductive tract of a male chicken. Figure 2.
When you crack open the egg, if it's fertile, you'll notice a small white spot on the top of the yolk about 4mm in width. This is called the germinal disc. This is what tells you if the egg has been fertilised.
Probably not. Ethical considerations preclude definitive research on the subject, but it's safe to say that human DNA has become so different from that of other animals that interbreeding would likely be impossible.
The transfer of sperm happens quickly without the penetration normal in mammal mating. The cloaca, or vent, of the male and female touch and sperm are exchanged. It's called a “cloacal kiss” and requires a bit of avian gymnastics for both birds to position themselves so their cloacas meet.
Does a rooster fertilize every egg? Not always. If a hen is frequently mating with only one rooster, he will fertilize most of her eggs. However, it is still possible that the occasional non-fertile egg will slip through.
How many hens per rooster for fertile eggs? To make fertile eggs a rooster should be kept with no more than 12 hens. Any more than this and he will struggle to fertilize the eggs. If you are having problems with fertility there are a couple of things to check on.
Fertility increased rapidly in young roosters to a peak of 96.2 +/- 3.9% at 37 weeks of age. Thereafter, fertility declined and by 72 weeks of age was significantly lower than at 37 weeks. Plasma LH reached 16.8 +/- 2.5 ng/ml at 27 weeks and remained high until 60 weeks of age, when it decreased significantly.
A rooster in his prime can 'cover' 1-16 hens. As he ages, he can successfully cover fewer hens, at age 3 years he is considered 'beyond prime'. A rooster's job is to ensure the success of his kind so mating with the hens looms large in his mind for many of his waking hours.
The earliest documented instance of a “rooster” laying an egg occurred in Basel, Switzerland, in 1474. The “rooster” was sentenced to death for the “unnatural crime of laying an egg.” A similar event took place, again in Switzerland, in 1730.
A rooster with an injured foot or leg may have difficulty breeding, resulting in reduced egg fertility. Low fertility may also result from an infestation of internal and external parasites, a disease, or a reaction to a medication, a pesticide, or a toxin (such as might occur in moldy feed).
A rooster may mate from 10 to 30 or more times per day, depending on the availability of hens and competition from other roosters. However, the number of sperm per ejaculate is seldom less than 100 million which is the minimum required to maintain high fertility.
The hen inverts her cloaca to meet the rooster's presentation of his and accept the semen into her reproductive tract. So..how DO they do the deed? The rooster gets into position, which resembles a piggy-back ride, standing on her back, holding her neck feathers with his beak and steadying himself with his feet.
If the egg has a pointed tip, it's a rooster. Hold them upside down by their feet and the rooster will spring back up quickly. A threaded needle held over the bird's head will swing back and forth over a rooster and in a circular motion over a hen.
A broody hen may sit on unfertilized eggs for six or seven weeks before she gives up. Between the minimal diet and the increased body temperature, that's not good for her health. A broody won't lay eggs. She'll just sit on the eggs that are already in her nest (or the eggs that the other hens lay)
Just because a hen is broody does not mean that she is going to be a successful or dedicated hatching hen. Some abandon the eggs after a number of days or weeks, or worse- they kill the chicks that hatch. Unfortunately, the only way to know whether a hen will be a good mother is by being a good mother.