THE VITAL 10 PERCENT FOR POULTRY

H. R. Bird

OF THE COMMON species of domestic poultry, only geese do well on a diet that is largely grass. Chickens, turkeys, and ducks require grains and other concentrates, and the proportion of grass that they can utilize effectively is small. But the economic importance of the grass in such diets is not small. In the nutrition of chickens, turkeys, and ducks, grass may be looked upon as home-grown vitamins, particularly vitamin A and riboflavin. If grass is not available, other sources of the vitamins must be bought.

Investigators disagree as to the amount of grain and mash feed that can be saved by providing pasture for chickens. Some have found no saving at all; others reported that growing birds or laying hens that had good pasture ate 5 to 20 percent less grain and mash than did birds confined on bare ground or on wire. The results were obtained without limiting the quantity of concentrate feed that was available to the chickens.

It is probably safe to estimate that under favorable conditions 10 percent of the dry matter of the diet of chickens on good pasture is furnished by the pasture.

So much for quantity, but what about the quality of this 10 percent? It furnishes one-eighth of the protein needed by growing chickens (more than 8 weeks old) and by laying hens. It furnishes about one-tenth of the calcium required by growing chickens and about one-twentieth of that required by laying hens, and about one-eighth of the manganese needed by laying hens if their eggs are to be used for hatching. These figures would justify some interest in pasture grass as a feed for chickens, but, as I said, its chief importance lies in its vitamin content.

The vitamins most likely to be lacking in poultry diets are vitamins A and D and riboflavin. Ten percent of grass in the diet would furnish several times the quantity of vitamin A needed by growing chickens and laying hens. It would furnish all the riboflavin needed by growing chickens or by hens whose eggs were not to be hatched and three-fourths of the riboflavin required by breeding birds. It would not supply vitamin D, but the sunshine to which birds on pasture are exposed would furnish 9 enough of this vitamin for growing or laying chickens.

Turkeys are better grazers than chickens, but if they are given free choice of mash,grain, and good pasture, grass makes up about the same proportion of the diet as it does in the case of chickens. Savings of mash and grain feed ranging from 3 to 19 percent have been reported as a result of providing good pasture. As in the case of chickens, the dry matter of pasture grass as 10 percent of the diet would Provide all the vitamin A and riboflavin needed by growing turkeys; sunshine would supply enough vitamin D. The diet of growing ducks frequently contains 10 percent of cut green feed, and the diet of mature birds may contain as much as 25 percent. The dry matter supplied by these quantities would amount to 2 or 3 percent and 5 or 6 percent of the diet, respectively.

For geese, grass is a complete diet during most of the life cycle. Young goslings require some grain during the first 3 weeks of life, and some grain is required by breeders during the period of egg production, but otherwise good pasture is all that is needed.

The best crop or combination of crops for poultry pasture is the one that provides the greatest quantity of succulent, actively growing material during the greatest part of the year. It has been reported that chickens, when given free choice, prefer oats to other grasses, and that they prefer cereal grasses to alfalfa. Such differences in palatability may be kept in mind in selecting a pasture crop, but only as a secondary factor.

Among the commonly used pasture crops, palatability depends less on species than on stage of growth. As plants approach maturity their fiber content increases, and they become less palatable to chickens and less digestible. So it is recommended that the crops that continue to grow after cutting be cut often lest they go beyond the stage of early succulent growth.

Chickens are not proficient as grazing animals. When they are placed on pasture they are likely to destroy the vegetation completely in a small area around the house and neglect the more distant parts of their range. For that reason, and also from the standpoint of disease control, it is well to use movable houses or range shelters.

When birds are reared on sod range, the danger from disease will be reduced if the range is divided into two parts, one part of which is used one year and the other the next year. If movable houses or shelters are used, as many as 800 to 1,000 chickens or 200 turkeys per acre can be reared on annual pastures. Good permanent pasture should support 300 growing chickens or 200 laying hens or 100 growing turkeys to the acre.

Shade is important to birds on range. If natural shade is not available, it is well to provide some other shelter from the sun at locations where the chickens are fed and watered. It has been suggested that a crop like Sudangrass may be drilled in rows 24 to 30 inches apart and that alternate rows may be cut occasionally to provide a continuous source of succulent green feed, while the remaining rows are permitted to grow tall to provide shade.

Chickens can be induced to graze more extensively by limiting the quantity of mash and grain. A saving of as much as 22 percent of the concentrate feed by this method has been reported. The practice is not recommended for laying hens because any limitation of their intake of concentrate feed is likely to reduce the rate and efficiency of egg production. There are several methods of restricting the quantity of mash and grain supplied to growing birds on pasture, and if the restriction is not too severe, growth and maturity will not be affected. For example, at the New York (Cornell) Agricultural Experiment Station, allowing pullets to have access to grain and mash only in the afternoon stimulated their consumption of grass without interfering with their development. Experiments at the Delaware Agricultural Experiment Station indicated that limitation of the mash and grain intake of pullets on range to 75 percent of the quantity that would be eaten if the birds were permitted free choice was too severe a restriction and retarded growth.