warrants it. The surface area of the silo should be such that the silage will be fed rapidly enough to prevent decay. It should never be more than ten square feet per cow, five is better; while seven and a half gives good results.

The riper the silage, the less weight the silo will hold. The higher the silo and the greater the diameter, the more weight the silo will hold. The weight and keeping quality will depend also upon the manner of filling. The material should be evenly distributed and the silage next the sides of the silo thoroughly packed by tramping in order to overcome resistance offered by the sides. The more slowly the silo is filled, the more it will hold. A silo sixteen feet in diameter and thirty feet high will hold, when continuously filled with suitably ripened maize, about thirty-three and a third pounds of silage per cubic foot, or about Ico tons of silage. A cubic foot of such silage is a standard daily ration for a cow in milk. The capacity of the silo required may be calculated in cubic feet by multiplying the number of animals to be fed by the days of feeding desired. Twelve tons of suitably ripened maize per acre is a good yield; eight to ten tons per acre is a safer estimate when calculating the land to be planted in order to fill the silo.

347. Losses in the Silo.-Babcock and Russell1 have shown that the changes which take place in the silage are not wholly due to bacteria, but partly, at least, to the respiratory activity of the yet living protoplasm of the plant tissue. The loss due to respiratory activity was shown to amount to about one per cent of the total weight of the silage, and was due to the carbonic acid (CO) gas evolved. King has shown that the unavoidable losses may amount to from two to four per cent. These are the losses in feeding value which cannot be prevented with a silo of the very best construction, filled in the best possible manner. The losses not due to respiratory activity are due to 1 Wis. Rpt. 1901, pp. 177-184.

Wis. Bul. 83 (1900), p. 64.

fermentative processes. tice cannot be accurately stated. Different stations have frequently reported losses of twenty per cent. It is probable that, with the proper construction and filling of the silo, and beginning to feed as soon as filled, the loss will not exceed ten to twelve per cent.

What the losses are in general prac

2

348. Loss of Maize Fodder by Curing.-Experiments at the Wisconsin, Vermont1 and Pennsylvania Stations show a loss of nineteen to twenty-one per cent of the dry matter of maize fodder from field curing. Maize fodder cut when nearly ripe lost about five per cent more than fodder cut when maize was in the roasting-ear stage, evidently due to the large amount of soluble carbohydrates in the former. (351) The loss, when stored in the barn October 29th, was one per cent greater than when allowed to stand in the field until December 18th. Ears cured upon the stalk with as little loss of dry matter (eight to ten per cent) as if picked and dried, but when put in the silo the loss of dry matter in grain was considerably greater. While not economical on account of labor involved, the loss of dry matter could apparently be reduced somewhat by husking ears and placing only the remaining portion in the silo. The losses. of the maize plant, both in field curing and ensiling, are largely in the carbohydrates other than fiber.

349. Time of Harvesting will depend upon whether the maize is grown for ears alone; for both ears and stover or fodder; or whether for silage. When grown for the ears alone, the plant is not only allowed to ripen, but the ears allowed to remain on the standing stalks until they have become dry enough to be placed in storage, which usually requires about a month after maize is ripe, or after the first killing frost. When stover is to be harvested, it is customary and desirable to allow

1 Vt. Rpt. 1894, p. 171. Penn. Rpt. 1892, p. 43.

the plant to become as ripe as is possible without the leaves falling off before or during the operation of shocking. The ears should be all, or nearly all, dented or glazed, the husks dry, and the leaves from one-third to one-half green. When cut for silage, it is necessary to cut a little greener in order that the mass may pack and sufficiently exclude the air. This condition is reached when many, but not all, the ears have become dented, a portion of the husks dry, and the bottom three or four leaves dry, with the rest still green. On the other hand, up to this stage of maturity, the greener the maize the greater the loss in the silo.

There are six advantages in allowing the plant when intended for silage to arrive at the stage of maturity indicated: (1) greater yield of water-free substance; (2) less weight to handle; (3) less loss in silo; (4) superior composition; (5) greater digestibility; (6) greater palatability; resulting in a greater feeding value per acre at less cost. The following table shows the influence of maturity upon weight of fresh and dry substance and loss in the silo:

350. Influence of Maturity Upon Yield.—There is no relation between the apparent size of the maize plant, as, for example, height, and the weight of dry matter. When the plant is in full

tassel it has reached from one-third to one-half its development, measured in weight of water-free substance. When the plant has reached the roasting-ear stage, three-fourths to four-fifths of the dry matter has developed, and when in condition to be put into the silo, from three-fourths to nine-tenths of its dry matter has developed.1

Neither is there any relation between rate of growth in height and the development of water-free substance. The greatest rate of growth in height precedes that of the development of dry matter. The total yield of grain increases up to full maturity. The yield of the whole plant has in some instances been found to decrease slightly in weight of water-free substance during the last one or two weeks, doubtless due to loss of leaves. The plant, exclusive of the ear, may decrease materially from translocation of material to the grain. The Iowa Station 2 found a decrease of dry matter in the plant exclusive of the ear to be seventeen per cent of dry matter from the time ears were mostly dented, but leaves and husks all green, until the plant was entirely ripe, requiring a period of three weeks. The circumstances surrounding the experiment lead to the inference that this loss represents a translocation of material to grain, although it may have been due in part to loss of material through dropping of leaves or otherwise.

351. Influence of Maturity Upon Composition.-In those grasses and other fodder plants in which the proportion of seed to whole plant is small and the seeds are of low digestibility a deterioration in the plant as a food for domestic animals begins before the plant reaches full maturity, both from a translocation of the material to the seeds and the loss of leaves and other finer parts. Analyses under these circumstances usually show an increased percentage of crude fiber and a decreased percentage of protein. When fed to domestic animals, the riper the product is, the less

1 Ill. Bul. 31, p. 361; Mich. Bul. 154, p. 283; Cornell Bul. 4, p. 52. Iowa Bul. 21, p. 778.

palatable and the less digestible it is. In the case of the maize plant, however, it has been found that not only does the total amount of dry matter increase, but the quality of the product increases up to or nearly up to the stage of complete maturity. There is an opportunity for the maize plant to lose its leaves if entire maturity is allowed, the extent of which depends upon weather conditions. On the other hand, the increase in the percentage of starch and of soluble carbohydrates is rapid during the latter stages of maturity coincident with the development of the ear, which constitutes so large a part of the whole plant and which is so completely digested by domestic animals. The result is that there is a decrease in the per cent of crude fiber as the maize plant ripens. The following analyses made at the Maine Station illustrate what in a general way has been verified by many stations:

1 2

Composition of Maize at Different Stages of Maturity.

IN ONE HUNDRED PARTS WATER-FREE SUBSTANCE.

352. Influence of Maturity Upon Digestibility.-A summary of American digestion experiments shows that both in the case

1 Me. Rpt. 1893, pt. 2, p. 25.

2 W. H. Jordan: The Feeding of Animals, p. 211.