Breeding Better Poultry
by THEODORE C. BYERLYTHE AVERAGE hen on our fathers’ farms laid 86 eggs a year. Today the average is 118 eggs, and in some flocks it is about twice that. Changes in management, systematic trap-nesting, and selective breeding brought about the improvement. The amazing wartime yield of eggs and meat, far exceeding all peacetime records, shows what a well- organized industry, aided by research, can accomplish.
But we are not satisfied: Experimental flocks and progressive breeders of poultry demonstrate how we can get even more eggs and more profits. For, as egg production increases, the income over feed costs rises more rapidly, and higher production is had at a lower cost per dozen eggs. In the better flocks, also, more eggs are laid in the winter months, when prices normally go up. Hard economics like this underlie the experiments directed toward improved blood lines.
Many poultry breeders have developed strains of chickens of the more popular kinds that lay 200 to 250 eggs during the first laying year—provided, of course, feeding, management, health, and sanitation are of the best. A breeder develops these outstanding strains by mating selected birds—selected because of proved ability to lay, pedigree, handsome appearance, and, finally, family proof that they can pass on to their offspring the genetic factors necessary for high egg production.
We have found by analyzing many records that selection and mating in this way enable many poultrymen to maintain high production and that the method is effective also in flocks that are not so good. In other words, rigorous selective breeding will improve a flock in a few years to a peak that can be maintained, but not heightened, by further selection. But if selection stops, production drops. Improvement through selective breeding is directly proportional to the correlation between individual and family performance on the one hand and genetic make-up on the other. To find out whether by developing and crossing inbred families we could boost average egg production beyond the level reached by such family selection and line-breeding, we have made comparisons of the two methods at Beltsville each year since 1940. Inbreeding (that is, the mating of closely related stock), followed by matings between unrelated families, parallels the production of hybrid corn, which greatly outyields its parent stock. The results of thus crossing inbred stock of two different breeds, as well as of the same breed, promise much.
The offspring of inbred families of the Single-Comb Rhode Island Red variety that we mated to inbred Single-Comb White Leghorns have steadily exceeded the average of the family-selected purebred parental strains by about 25 eggs a pullet during the first laying year. These incrossbred pullets were relatively nonbroody; many crossbred pullets are excessively broody. Incrossbred pullets may be excellent layers, but their records do not exceed those of the best purebreds, and it remains to be, determined whether they are consistently superior to all family-selected strains of purebred chickens.
Hatcherymen and poultrymen who raise chickens for meat may improve the quality of their breeding stock by selecting birds for three main characteristics—fast feathering, rapid growth, and superior conformation. This plan of selection, which begins with young chicks, does not affect egg production and does not greatly increase management costs.
Fast feathering is desirable partly because it reduces the number of pinfeathers in market birds. Indications of fast feathering in day-old chicks are the length and number of the wing-feather sheaths. The best chicks for broiler stock have well-developed primary feathers—the large outer wing feathers—and well-developed secondaries, which number six or more and lie next to the primaries. Slow-feathering chicks have fewer secondaries and primaries that are not so well developed. You can easily find the feather sheaths in the down at the outer edge of the wings. If vou select chicks of the desired type for next year’s breeding flock, you should raise them by themselves or mark them in some way, by a wing band or leg band, for instance.
You can best judge the ability of chickens to grow rapidly by their body weight when they are 1 to 2 months old. Those that have made the most satisfactory gains should be kept for the breeding flock. You can make another check for growth at the age of 5 months, when you can remove from the special group any birds that are below expectations.
Superior conformation for meat production is indicated by good development of the breast when chickens are about a month and a half old, and not later than 3 months. Because the breast meat is the most valuable part of a broiler, only birds with well-meated breasts should be kept for use as breeders.
In producing broilers, the practice of crossing certain breeds or varieties has been popular and successful. Crossbreds commonly produce more meat for feed consumed than the purebred parents, they feather more satisfactorily, and fewer die during the growing period. Crossbred pullets and hens, however, tend to be broody oftener than the parent stock. Birds from Barred Rock roosters and New Hampshire or Single-Comb Rhode Island Red females are especially popular for meat production. Cross-breeding is less widely used for laying stock, although one advantage in crossing between certain breeds is that one can identify the sex of chicks at hatching time because of differences in the down color or feathering. For this purpose, nonbarred red, buff, or black roosters and barred hens may be used, or roosters with gold in their plumage may be bred to silver females.
In experiments covering 3 years, we made two- and three-way crosses of Rhode Island Red, White Wyandotte, and Light Sussex. We found that the crossbred progeny generally outgrew standardbred Rhode Island Red pullets up to 10 and 20 weeks of age, and matured somewhat earlier. Those of the two-way cross were 6 to 10 percent more viable, and the progeny of the three-way cross were even better in this respect. The crossbreds were no better than standardbred stock, however, in annual egg production, egg weight, hatchability, and weight of mature birds.
We bred by genetic selection a strain of rapid-feathering and fast-growing silver chickens with Columbian pattern from the offspring of these crosses. This strain now breeds true in major characteristics. After a few more years of improvement in egg production and meat type, it will be useful for broiler production. Its advantage over good rapid-feathering Barred Plymouth Rocks is that the progeny of Columbian males in both pure matings and crossbred matings with New Hampshire or Single-Comb Rhode Island Reds have light colored pinfeathers. Housewives accept the barred feathers of the purebred or crossbred progeny of Barred Plymouth Rock males as a mark of quality. Now that more broilers are marketed dressed, and often drawn and cut up ready to cook, the dark pinfeathers are a serious disadvantage.
We have also been successful in breeding operations designed to get a small turkey of good conformation that is more suitable for family use than the larger kinds. The type of such a bird has been reasonably well fixed. The new turkey is named Beltsville Small White, so called from its place of origin, small size, and white color. Several thousand such birds of acceptable quality have already been produced. Hatching eggs have been distributed through State experiment stations to commercial breeders and considerable commercial production has resulted.
Beltsville Small White young toms weigh 12 to 17 pounds alive at market age. Young hens weigh 7 to 10 pounds—roughly about two- thirds the weight of mature standard-size birds. The body is compact, with much breast meat. The legs and neck are relatively short.
Artificial insemination has scientific and commercial possibilities in breeding chickens and turkeys. Department workers developed a simple way to obtain semen from chickens and turkeys and to inseminate the females. Fertility has proved high, and many breeders have shown interest in the method; but, except in turkeys, its commercial use has been limited. Research workers, however, use the technique to effect fertilization when birds cannot or will not mate naturally—to make crosses between bantams and larger varieties of chickens, for example.
Some researchers in nutrition employ the practice to fertilize the eggs of hens kept in batteries, so they can get information on experimental diets, fertility, and hatchability. A few poultrymen also use it for hens kept in batteries. Breeding hens are not usually kept in batteries, however, and many poultrymen prefer to mate a proved sire naturally with an unusually large number of hens, risking some infertility, rather than to undertake the additional effort.
Turkeys, particularly the Broad-Breasted Bronze, have shown considerable infertility, and some turkey raisers breed them artificially to overcome the fault. Other growers, encouraged by experiments at the Texas Agricultural and Mechanical College, have improved the reproductiveness of Broad-Breasted Bronze turkeys through genetic selection for well-balanced body conformation.
Broodiness in turkeys, as in chickens, cuts egg production, causes extra labor, and increases costs of producing poults. We believe we can develop relatively nonbroody strains, and have started working toward that goal at Beltsville.
Persons who prefer not to breed poultry but rather to purchase stock, cither as day-old or larger birds, can do so now with prospects of obtaining much better stock than was available several years ago. Coordinated Federal, State, and commercial activities have been directed toward a wider use and better supervision of improved breeding methods. Examples of this trend are the National Poultry Improvement Plan for chickens and a similar plan for turkeys.
Use of males from bred-to-lay strains has been one of the principal factors responsible for the increase of 25 eggs a hen in course of the 10 years the National Poultry Improvement Plan has operated. A further increase is probable, because only about 30 percent of hens in hatchery-supply flocks are mated to males one or both of whose parents were officially pedigreed. Besides, as farmers get better stock they feed and manage their flocks better so as to get the most from their improved birds.
Bred-to-lay stock of chickens, representing any one of four progressive breeding stages, can be had from hatcheries and breeders. The stages, each with successively higher requirements, are: U. S. Approved, U. S. Certified, U. S. Record of Performance, and U. S. Register of Merit. The turkey plan stresses efficiency in meat production. For both species of birds, official flock and hatchery inspections and other forms of supervision provide reasonable assurance of obtaining the degree of quality desired.
As a further guide to persons seeking superior chickens, the Department of Agriculture now issues an annual directory of birds that have qualified for U. S. Register of Merit, the highest breeding stage.
Recognition is given to sires and dams on the basis of the productivity of their daughters, of which at least a third of those entered in the third-highest stage of the plan must have annual records of 200 eggs or more. Other requirements cover acceptable size of eggs and physical characteristics of the birds. More than 14,644 birds have thus far met the specified high standards. As evidence of the egg production to be reasonably expected from daughters of U. S. Register of Merit dams, officials in charge of the National Poultry Improvement Plan report that the average production of 28,248 such daughters was 208 eggs in 1944.
The use of airplanes for transporting hatching eggs long distances has prompted experiments to find out if high altitudes affect hatchability. They apparently do not. In our investigations we used reduced air pressures to simulate altitudes of 7,000 feet, 12,000 feet, and more, and discovered that the eggs under test, when incubated in the usual way, hatched after 3 days’ exposure to a rarefied atmosphere equal to that at 15 miles above the earth.
Consumers prefer eggs with better shells, substance, and keeping quality; poultrymen like them because they cut marketing costs and losses.
We did some research on the thickness, porosity, and related characteristics of eggshells, as shown by shrinkage of their contents during storage; and found indications that the characteristics are inherited. Our studies, made with two different lines of chickens, also point to the improvement of shell quality by selecting families of breeding birds on the basis of blood lines that produce eggs that shrink little in storage.
Studies on the interior quality of eggs have shown that blood spots in eggs come from inherited faults. Poultrymen, therefore, are wise to cull their breeding flocks of hens that lay eggs containing blood spots, which cause great loss to producers, market agencies, and consumers. Our studies showed us the falsity of the common belief that handling birds, moving them about, or frightening them cause their eggs to contain blood spots. We found also that because many blood spots are very small (less than a thirty-second of an inch in diameter) candling is only about 50 percent efficient in detecting them—another reason for culling birds that are known to produce eggs with blood spots.
We also selected families of chickens on the basis of the rate at which the albumen in eggs deteriorates. One line developed in this way produces eggs which, when infertile, remain fit for table use after being held 2 weeks at 99° F. The albumen remains fairly thick in these eggs after such mistreatment, but another line of hens lays eggs that have no visible thick white after similar treatment. Poultrymen can use this method of selection in order to supply housewives with eggs of outstanding quality even if refrigerated transportation and holding facilities are lacking.
THE AUTHOR
Theodore C. Byerly is in charge of poultry investigations in the Bureau of Animal
Industry. He is a graduate of the University of Iowa and for several years taught
poultry husbandry at the University of Maryland. In 1943 Dr. Byerly received the
Borden award for outstanding work in poultry research.
FOR FURTHER READING
Barott, H. G.: Effect of Temperature, Humidity, and Other Factors on Hatch of Hens’ Eggs and on Energy Metabolism of Chick Embryos, U. S. D. A. Technical Bulletin 553, 1937.
Burrows, William H., and Quinn, Joseph P.: Artificial Insemination of Chickens and Turkeys, U. S. D. A. Circular 525, 1939.
Godfrey, Albert B.: Poultry-Breeding-Stock Selection for Desired Characters, U. S.D. A. Circular 715, 1944.
Quinn, J. P.: Selecting Hens for Egg Production, U. S. D. A. Farmers’ Bulletin 1727, 1934.
ALSO, IN THIS BOOK
Artificial Breeding, by Ralph W. Phillips, page 113.
Keeping Poultry Healthy, by Theodore C. Byerly, page 231.
Feeding Poultry, by H. R. Bird, page 235.
HIGHER QUALITY MEAT AND EGGS from poultry, and greater efficiency in feeding and taking care of domestic fowl, are some of the objectives of research by the Department in cooperation with several State experiment stations. On page 225 T. C. Byerly discusses the breeding of better poultry [above], and on page 231 he reports results of work on how to keep poultry healthy. The next few pages show how the work is done and some of the results.
Fast-feathering chicks are better for table use because they have fewer pinfeathers when ready for market. Of the two same-aged chicks (left), a strain of the new Columbian chicken, the upper one has well-developed tail and wing feathers. This is done by selective breeding.
