reaches a more advanced stage of maturity is the best for silage.' These last two quotations indicate an appreciation of the problem of the intensive dairyman, although it is only fair to also credit Hays (9) as early as 1894. It is interesting to note that Hunt (12) in his "Cereals in America," 1904, does not even discuss varieties or types of silage. Eckles (13) makes the following statement in the revised edition of his text: "In northern states, larger yields may be obtained from some of the special silage varieties, but these produce a lower amount of grain, and it is questionable if the total nutrients exceed those from varieties grown for grain." Here we see agreement with the position of the early workers in the East rather than with those of the Middle West. Montgomery (14) in the "Corn Crops" says, "In the southern states and in practically all the Corn Belt States, perhaps the best silage variety is also the standard variety grown for grain. In New England, and on higher elevation in all northeastern states, the most profitable silage variety will probably be too late to mature." Very recently Savage and Maynard (15) offer the following: "We believe that the variety which will reach the glazing stage before frost will give the best satisfaction." Even Henry and Morrison do not make clear the distinction between "general farming" and "intensive dairying." Their discussion of "Variety of Corn for Silage" (16) does not recognize this distinction, so clearly discussed by Williams and Welton (10). Thus we find disagreement among college and station workers, although the chief difficulty seems to be a lack of common ground or point of view in considering the problem. Even granting that the question is confined to that of silage on the intensive dairy farm, we find conflicting results obtained in the actual feeding trials reported. The best of these were the Maine and Minnesota experiments and the conclusions were opposite. In practice there is also wide variation, but in New England many farmers grow late varieties, in spite of years of advice to the contrary. Since the work here reported was begun, Hayden and Perkins (17) have reported a five year feeding trial at Ohio. Their VARIETIES OF SILAGE CORN FOR MILK PRODUCTION results slightly favor the late variety until corrections are made for gains in weight, when the early variety leads, producing 1.74 lbs. more milk per ton and 1,152 lbs. more per acre. However, the method of handling the crops and feeding were not typical, at least of northeastern practice, and the difference between the dry matter percentages was very small, 1.93 percent. The two varieties used were also less than two tons apart in yield. PRELIMINARY FIELD TRIALS. In 1914, field trials of varieties and strains of corn were begun by the Agronomy Department at Storrs. Early results indicated that late varieties did not yield as much. dry matter as those that would practically mature, but as data accumulated this has proven to be incorrect as shown by the table below. TABLE 1-YIELDS PER ACRE OF SILAGE Corn. (Average of 5 years at Storrs) (It should be borne in mind that these are distinct groups of several varieties each. All were planted and harvested at the same time each year, and they represent the varieties grown in actual practice in New England.) Considering yields only, it would seem logical, therefore, to grow a late variety. An attempt was made to compute the feeding value of the several silages on the basis of digestion coefficients available through the work of Lindsey and Armsby, and to use these results in an equation that would give the feeding value per acre. This proved fruitless because, first, the published coefficients are given simply as for "Mature" and "Immature" corn, and second, these coefficients do not throw sufficient light on the "milk producing value" of the several feeds. It was then decided to undertake a feeding investigation to answer these questions. GENERAL PLAN OF THE EXPERIMENT. The data here presented deals with results of three feeding experiments. The first two have been reported in preliminary papers. (24 and 25). In subsequent trials, now in progress, the silages are being compared on a "dry matter" basis. Three varieties of corn were chosen, one representing the very late group (called "late" hereafter), one the group that can be expected to mature (called "early"), and one lying midway between these (called "medium"). The feeding comparisons were based on the following facts and assumptions: 1. The chemical analyses of these types of green corn had shown a consistent spread in dry matter, about 20, 25 and 30 percent respectively. 2. Although no data was available, the analyses of the resulting silages should also show wide differences. (This assumption proved to be correct.) 3. By making silage, a large part of the ration (50 pounds per day) the possible differences in feeding value should be more marked. (To conform to practice in the intensive dairy regions, the silages were fed on an equal green weight basis). 4. By keeping the animals at constant weight through control of the grain ration, differences in nutritive value, if any exist, should show in the milk yield. 5. If constants could be established for milk production per unit of each silage, an acre value could be computed for each type of silage. EXPERIMENTAL PROCEDURE THE SILOS Three small silos, 36x6 feet, were purchased and erected during the summer of 1920. They are of spruce staves, set on a concrete base without drains and are covered with separate conical, metal roofs. The inside surface is treated with a wood preserver supplied by the manufacturer of the silos. VARIETIES OF SILAGE CORN FOR MILK PRODUCTION The diameter, 6 feet, is small, to allow feeding to a small group of cows without spoilage. Normal silage can be produced in very small containers as has been shown by Eckles et al. (18), Newton (19), and Westover and Garver (20). No difficulty was met in this respect. Silage, in the usual ration, is only one of the food components and comprises, in nutrients supplied, approximately one-third of the total amount consumed. Some investigators who were consulted, while the experiment was being planned, felt that the difference in feeding value of silages of different maturities would not be successfully indicated by a feeding trial. To have the silage contribute a considerable proportion of the total nutrients, therefore, seemed necessary. With this in view, the plan adopted called for the feeding of 50 pounds of each type daily to all animals that were found, in the preliminary trial, capable of eating this amount. It was assumed by limiting the hay, that all of the larger cows would consume 50 pounds with very little waste. Some were fed only 40 pounds daily as noted later. The feeding of 50 pounds daily, while high, is in line with the practice in a good many herds. In order to eliminate variables, these amounts were adhered to throughout the experiment. The silage was removed twice daily from the silos in burlap bags at feeding time, weighed to each animal, and recorded as was also the amount left by each cow. The refuse was small, however, as will be seen in the tables. THE HAY FEEDING The hay used in the first two years was from a uniform lot of baled hay purchased at the beginning of each feeding trial. It consisted chiefly of timothy with a small amount of redtop and clover. The quality was quite similar to a great deal of New England hay with respect to legume content, and more uniform, it is believed, than hay of a higher clover content would have been. The third year the herd hay was used, consisting of mixed grasses as cut from the College Farm. The hay was fed soon after noon each day. Four pounds was the amount fed to each animal the first year. It was found that they would consume more, without waste, even with the large amount of silage, and six pounds daily was supplied the second and third years. The cows were restricted to this amount of hay as it was desired to reduce the variables to the greatest possible extent by having all consume the same amount. THE GRAIN FEEDING A grain ration that has been widely used for experimental feeding of dairy cows consists of 4 parts cornmeal, 2 parts bran and 1 part oilmeal. This ration was recommended by a committee of the American Dairy Science Association a few years ago. However, it seems better adapted for feeding with alfalfa or clover hay than with mixed hay, neither does it contain cottonseed meal which is in common use as a dairy feed in the East. Consequently a ration consisting of 3 parts cornmeal, 3 parts wheat bran, and 2 parts cottonseed meal (36% protein) seemed best adapted. Such a ration supplies a good amount of protein, bulk, and palatability. |