Main chicken breeds

Below it is included a list where the main chicken breeds and varieties used in current breeding programs, or used for the development of synthetic breeds, is detailed in Animal Production.

Leghorn White

It is the only one that has managed to survive in the era of commercial white egg production. All Leghorns have yellow skin. Although only one variety is used, some of them can be sexed by plumage at the age of one day in other types.

Rhode Island Red

It has a long, cube-like body, a simple crest and lays brown eggs. Its skin is yellow and its plumage is red with some black feathers on its neck, back, tail and wings. During the last few years, the Red Rhode Island has been used almost exclusively for sexual intercourse with the offspring.

New Hampshire

It was generated from the Red Rhode Island; in a breeding process, whose purposes were high egg production and high hatchability. In the course of this process, the feathers became whiter, being light red in plumage. At first, this line was recognized as a high producer of eggs, although today is recognized for being a bird producer of excellent quality meat. For several years, it was a leading breed in the production of chicks for fattening. In spite of all this, few producers of fattening birds have commercialized this line; however, it is sold in many foreign countries mainly to exploit its meat.

The New Hampshire has been used as the basic breed for the development of many synthetic breeds of broiler chicken and is still used for this purpose today. In addition, its ability to produce large numbers of eggs that hatch well is a valuable characteristic for many genetic combinations.

Playmouth Rock White

It is a single-crested, yellow-skinned variety. Its white plumage is a feature that gives producers and processing plants an advantage, since these birds pluck better than those with other colored plumage.

However, this line, from the genetic point of view, is slow feathering, being a disadvantage for the production of quality broilers. However, most of the lines that come from these birds are now fast feathering.

Cornish

These chickens have a chickpea crest, lay brown eggs and have yellow skin. Their body type is very different from most other lines. Their legs are short, the body is wide and the breast is broad and muscular.

Their characteristics are acceptable to the meat producer, but their egg production is low, and they lay small eggs with low hatchability.

Plymouth Rock Barrada

It has feathers with black and white bars, which give the bird a greyish experience. It has a simple crest, yellow skin and lays brown eggs.

As the demand for commercial eggs increased, consumers in many countries showed a preference for white-shelled eggs over brown, so the popularity of this line declined. Nowadays this line is mainly used as the female part in the crossing with male Rhode Island Red specimens, to produce self-sexed in the progeny used as commercial brown egg-laying hens. The characteristic of self-sexed has driven the popularity of this cross.

Sussex Clear

It is a line of meat type, predominantly British with some varieties, the clear variety is one of the popular ones. It is a white-skinned bird, lays brown eggs and is a good meat producer. In England and other European countries, in order to produce white-skinned broilers, males of this line were crossed with females of some other yellow-skinned meat line.

Chicken breeds. Characteristics for breeding

Modern egg production lines

The egg producing strains are integrated with chickens for commercial egg production with any type of shell, white or brown. The birds are relatively small in size, laying a high number of eggs with strong shells. Their viability is good and their egg production economical.

White egg strains

Virtually all commercial white egg dick strains are now Leghorn White Single Ridge. In the beginning, the strains were pure, this means that no cross-breeding existed.

Today, the most common practice is to cross one or more strains to produce a commercial chicken.

Single Breed: The common producer uses an isolated flock, continually selecting the best birds from each generation to breed from each other using only a small percentage of the best birds for crossbreeding. Pullets are normally kept in production for one year, so that various determinants of egg production can be measured. The selection of the best birds is made at the end of the first year of egg production.

The selection includes characteristics such as:

Crossing of lines: more than selecting for superiority of good characteristics, within a single line, many breeders rely on the selection of some characteristics of a certain line and then cross two or more lines to generate a commercial chick that is related to their interests.

Crossing of 2 lines: this system increases the heterosis in the descendants, defined as an increase in the improvement in force or capacity to increase the productivity, to obtain the maximum improvement of that crossing, a line is generated to highlight certain characteristics, while the other one is improved in other aspects. The following is a simplified example of the crossing of two strains:

Male lineage: bred for viability, large body size and egg size

Female strain: bred for egg production, shell quality and internal egg quality.

The elements mentioned are the most outstanding, although there may be many others for each lineage.

When 2 strains are crossed, the resulting pullets are used for commercial egg production and their characteristics will be:

Crossing of three strains: three strains with different qualities each are developed. Two are crossed and the descendants of these are crossed with the descendants of the third lineage. Although the increase in the number of strains generally increases the costs of producing commercial pullets, the advantages usually outweigh the additional expense.

Crossing of four strains: Four strains are developed. Two of the four strains are crossed, as are the other two. The descendants of each cross are crossed with each other to produce the commercial pullets.

Brown egg strains

Although it is known that the color of the shell has no influence on the nutritional value of the egg, in certain places there is a consumer preference for a certain shell colour. While white eggs are preferred in the United States of America and Germany, brown eggs are preferred in France, the United Kingdom and the Far East.

Several breeders have used special strains or crossbreeds for the breeding of commercial brown-brown egg-producing birds.  In some cases, two breeds or varieties are used, thus achieving not only that the birds lay brown eggs, but also that the chicks can be selected according to their sex, at the day of age, by the difference in color.

When a Red Rhode Island male mates with a Plymouth Rock Barrada female, the male chicks’ offspring are black with a white spot on their head. Consequently, this crossing makes it possible to select the sex of the chicks at birth according to color, a procedure generally known as color sexing.

To make the crossing, special strains of egg-producing Rhode Island Red and Phymouth Rock Barrada are used which are coupled. In some cases, other varieties have been mated to generate offspring that put the sexing by color of the offspring through the use of silver and gold genes. Synthetic strains have also been developed that, when crossed, produce differences in chick color according to their sex at birth.

Brown-shelled egg-producing birds are 30 to 50% larger than white-shelled egg-producing birds. This relatively large size increases the cost of feed to produce the eggs, because a large bird consumes more feed than a small bird. It usually costs more to produce a dozen brown eggs than a dozen white eggs.

The production of brown eggs from bird lines is similar to that of white egg producers. In most cases, brown egg-producing strains lay larger eggs than white egg-laying strains.

During the last few years, several small chicken strains have developed on the market. These birds should not be confused with “Bantam” chickens. Dwarfism in small breeds is due to a recessive gene linked to sex. However, the gene manifests itself differently in meat and egg strains.

Dwarfism in modern small Leghorn females, when compared to normal chickens have the following differences:

• Birds are 5 to 10% lighter at 8 weeks of age and 25 to 30% between 25 and 30 weeks of age. The small size is due to the low activity of the thyroid gland and growth hormone.
• Stride length is approximately 20% shorter.
• The red blood cell count is higher.
• Bird’s food intake is 10 to 20% less
• Egg is about 10% lighter.
• The food needed to produce a dozen eggs is about 5 to 10% less.

Because of their small size, these birds require less floor space in the house or cage, allowing more birds to be kept in confinement within a given area, which translates into an economic advantage. However, because of the smaller size of these birds, the value of the carcass at the end of the one-year laying period is very low, sometimes the depleted birds are of no value.

After considering the advantages and disadvantages, we can consider that the small Leghorn has not been able to take the place of the conventional size Leghorn; the gains are not always satisfactory.

In addition, results are highly variable when measured in profit per dollar invested; small breeds commonly provide a lower profit than normal birds. However, improvements in breeding techniques are making these birds more popular, taking their place in commercial production.