POULTRY PRODUCTION MANUAL
MALE REPRODUCTIVE SYSTEM
The avian male reproductive system (see Figure 3.16 and Figure 3.17 below) is all inside the bird – unlike mammals which have the testes outside of the body. The male chicken possesses two testes, along the back, near the anterior ends of the kidneys. They are elliptical shaped and light yellow in color. Each ductus deferens opens into a small bump, or papilla, which is on the dorsal wall of the cloaca. The papillae serve as the copulatory organ. The incorrectly named, "rudimentary copulatory organ" is located on the medial ventral portion of the cloaca and is used to classify the sex of baby chicks.
The main goal of broiler breeder management is to produce hatching eggs. However, the only good hatching egg is a fertilized egg. Fertility, the percentage of eggs laid that are fertilized, is very important in hatching egg production. If an egg is not fertilized, then, of course, it will not contain an embryo and will not hatch. Simply put, "Hatchability can never be better than fertility."
Fertility is affected by both the male and the female, and both tend to decline as the chickens age. Flock fertility is dependent on the reproductive status of the chickens (i.e., level of egg and semen production) combined with the chickens’ interest and capability of mating.
The fertility of a broiler breeder flock usually increases from a low of 65-75% at the start of lay (23-24 weeks of age) and peaks at 95-98% at 35-37 weeks of age. Between 40-45 weeks of age fertility declines and the older the birds get the faster the decline in fertility.
From the female side, the decline in fertility is believed to be due to faster release of sperm from the sperm storage tubules. As a result, after 40 weeks of age the breeder hen needs more frequent mating to sustain high fertility.
From the male side it is presumed that there is a decrease in sperm quality as the rooster ages, as well as a decrease in mating activity. There is also believed to be an increase in early embryo death in the second half of the reproduction cycle. These early deaths often appear as ‘clears’ and may be mistaken for infertiles.
Walking through the supermarket, it is often possible to find capons for sale. While it is obvious from the shape of the packaging that it is a bird of some kind, there is often no indication in the labeling of what exactly a capon is. An informal survey of 4-Hers with poultry projects and university students very few knew what a capon is.
In caponization, the surgical castration of male chickens, the testes of the male chicken are completely removed. As a result, the cockerel fails to develop certain male characteristics or tends to lose them if they are developed. Capons are usually quiet and docile, lacking a cockerel's disposition to fight. The comb and wattles cease growing after castration, so the head of a capon looks small. The hackle, tail and saddle feathers grow unusually long.
Removal of the testes, and thus elimination of the male sex hormones they produce, reduces the male sex instinct and changes their behavior. They will become more docile and less active. Energy that is normally expended in fighting, courting behavior, and territorial protection is greatly reduced, allowing more efficient conversion of feed into growth, fat deposition and improved meat quality.
Caponizing produces a unique type of poultry meat grown for a specialized market. The meat of uncastrated cockerels tends to become rather coarse, stringy, and tough as the chickens age. This is not the case with the capon. Caponized males grow more slowly than normal male chickens and accumulate more body fat. The concentration of fat in both the light and dark meat of capons is greater than that of intact males. It is claimed that the capon meat is more tender, juicier, and more flavorful than regular chicken.
Any breed of chicken can be caponized. Over the past 100 years breeds that were particularly favored for capon production included Jersey Giants, Brahmas, Orpingtons, Cornish, Plymouth Rocks, and Cochins. Today commercially grown capons are produced using the Cornish x Plymouth Rock cross typically used by the commercial broiler industry. Male birds are typically caponized at two to four weeks of age. The testes of a male chicken are located within the abdominal cavity. A good caponizer can operate on about 200 birds per hour. Commercially grown capons are marketed at 15 to 18 weeks of age. The goal is a capon weighing six to eight pounds at packaging (9 to 11 pounds live weight).
Today, relatively few capons are marketed commercially in the United States. It is estimated that around a million capons are produced annually. This is in contrast with the 8 billion broilers produced each year. Today commercial capon production in the United States is now limited to a single producer, Wapsie Produce Company in Iowa.