Keeping Poultry Healthy

by THEODORE C. BYERLY

BECAUSE average death losses among growing chickens and laying hens add about 2 cents a dozen to the cost of producing eggs, poultry owners make money by keeping their flocks in good health. It is not easy to do, for more than 50 different diseases and parasites constantly threaten poultry. The first step in dealing with an unfamiliar ailment is to determine the cause as a basis for applying appropriate cures.

Pullorum disease, one of the most insidious and devastating of all poultry maladies, no longer takes the heavy toll it once did. The National Poultry Improvement Plan, established in 1935 and now operating in 47 States, contains specific provisions for its control. Similar provisions are contained in the National Turkey Improvement Plan, now active in 42 States. The plans have four progressive pullorum-control classes, which represent different stages in the suppression of the infection in breeding stock and deal with related steps to protect hatcheries, eggs, and chicks against infection by pullorum organisms. The key to most of the work is the simple stained-antigen rapid whole-blood test, developed by Department scientists for diagnosing the disease in breeding stock. On the basis of the current volume of testing and relative survival rates of chicks in tested and untested flocks, it saves poultrymen millions of dollars.

The chief precaution in dealing with this highly infectious malady, which breeding flocks transmit through the eggs, is to be sure that new stock—either mature birds or newly hatched chicks—are from properly pullorum-tested sources. One of the newer research contributions to pullorum disease control, announced in 1943, was the use of an improved medium for producing the stained antigen used in the test. The new medium consists of colloidal sulfur suspended in glycerol, and gives a greatly increased yield of the bacteria needed for preparing the antigen.

The practice of culling all hens at the end of their first laying year and thus keeping only pullets in laying flocks helps prevent transmission of several diseases, especially respiratory diseases and avian tuberculosis, from old birds to young ones. All-pullet laying flocks lay more winter eggs than hen flocks, and are generally more profitable. The plan is being adopted widely, especially among owners of flocks of the heavy breeds.

For coccidiosis, a parasitic disease, medication with sulfaguanidine, one of the sulfa drugs, is effective. It prevents, to a large degree, severe coccidiosis in chickens. It also permits a sufficient number of the infective organisms to develop to immunize the birds against the highly fatal form of cecal coccidiosis. Indications are that sulfaguanidine will help prevent severe outbreaks of intestinal as well as cecal coccidiosis.

Continued heavy losses from fowl paralysis and other forms of the avian leukosis complex have stimulated both State and Federal research, which is actively in progress. Paralysis and other nerve involvements, although frequent expressions of the disease, represent only one type. The inclusive term "avian leukosis complex" is appropriate because of the varied manifestations of this disease. Practically all tissues, organs, and other parts of the body have been found to be involved. Thus far no drug, vaccine, feed, or other product has been found that can cure it.

Recommended preventives are sanitation and quarantine measures. The use of breeding stock from families of high viability offers promise of reducing losses from this group of diseases. Research at the Regional Poultry Laboratory at East Lansing, Mich., and at Cornell University has indicated that brooding chicks in clean quarters separated by several hundred feet from any adult poultry is another way to cut losses. Apparently chicks are most susceptible when hatched and grow increasingly resistant to the disease with age.

Many other details affect the earning power and general well-being of poultry, among them housing, equipment, and exercise. Research and practical experience have worked together to give us several improved and profitable practices. Some of these differ from those advised and followed even as recently as 1940. I list several of the recommendations that are typical or that research workers believe have value :

Move portable brooder houses to clean ground before the chicks arrive, as a defense against coccidiosis, roundworms, and tapeworms. The term "clean ground" refers to land that has not been used by chickens or turkeys or been fertilized by poultry droppings within 2 years. As an added precaution against the same dangers, do not permit chicks or poults to mix with older birds, and do not permit visitors to enter brooder houses or yards.

For litter in the brooder house, use deep, absorbent material. Begin with at least 2 inches and add new litter each week until the total depth is about 4 inches. Crushed corncobs, shavings, dry sawdust, or a good commercial litter is suitable, but not straw alone unless cut into lengths of 2 inches or less. For the first 5 days, while the chicks are learning what and where to eat, keep the litter covered with sacks or building paper. Stir the litter at least three times a week. Unless an infectious disease occurs, the litter need not be changed during the brooding season.

A good litter is advised also in laying houses; begin with a depth of 3 inches and increase to about 6. Besides reducing disease hazards, litter helps insure against lowered egg production. House pullets in buildings or laying shelters by themselves—never add pullets to a flock of old hens even though the hens have been carefully examined and appear to be in perfect health. The reason is that adult birds, even though showing no visible symptoms, may transmit several infectious diseases.