The Book of Alfalfa: History, Cultivation and Merits / Its Uses as a Forage and Fertilizer

by F. D. Coburn

RELATIVE VALUES OF DIFFERENT CUTTINGS

The most interesting experiments comprehending tests of the comparative yield, composition and digestibility of early, medium and late cuttings of alfalfa, of the first, second and third crops; the relative feeding value of the various cuttings, and of the different crops, have been made at the Utah station, details of which are recorded in the station’s bulletins Nos. 31, 44 and 61. These tests and investigations extended continuously through a period of five years, and following are the more important facts developed and the conclusions that may be legitimately drawn from them, as summarized (Bul. No. 61) by Profs. Luther Foster and L. A. Merrill who supervised the work:

1. The largest annual yield of hay per acre is obtained by the method of early cutting and the lowest by the late, the average result standing as follows: early cutting, 100; medium, 92; and late, 85.

2. The early cut alfalfa contains the highest per cent of protein and fat, the most valuable food constituents, and the lowest per cent of crude fiber, the most indigestible portion. The former decrease constantly while the latter increases rapidly from early bloom to the full maturity of the plant.

3. The proportionate amount of leaves to stems is greater at early bloom that at any subsequent time, and both leaves and stems contain a greater per cent of protein and a less per cent of crude fiber at this time than at any later period in the growth of the plant. The relative proportion of leaves to stems in the different cuttings is as follows: early, 42 to 58; medium, 40 to 60; and late, 33 to 67.

4. Alfalfa leaves as compared with stems are very much richer in protein, fat and nitrogen-free extract, and they contain a much smaller proportion of crude fiber. The per cent of the protein and fat grows constantly less, and that of the crude fiber greater, from the time of early bloom to maturity. The average composition of all cuttings and crops shows the leaves to contain 150 per cent more protein than the stems, 300 per cent more fat, 35 per cent more nitrogen-free extract, and 256 per cent less crude fiber.

5. The more important nutrients, protein and fat, have the highest per cent of digestibility in the early cuttings and it grows less and less with the age of the plant.

6. In the feeding tests, the highest gains were made from the early cuttings and the lowest from the late, the results standing proportionately as follows: early cutting, 100; medium, 85; and late, 75.

7. The variation in the amount of the different cuttings eaten per day was very slight, being the highest for the early cutting and the lowest for the late, but the quantity of dry matter and also of digestible matter required for a pound of gain was decidedly lowest for the early cutting and highest for the late, the relative amounts of dry matter standing as follows: early cutting, 100; medium, 131; and late, 166.

8. The annual beef product per acre was largest from the early cuttings, not only in the general average but in each separate season’s test, and that from the late cuttings was smallest, the proportional products standing as follows: early cutting, 100; medium, 79¹⁄₂; and late, 69¹⁄₂.

9. Taking all points of comparison into consideration, both separately and collectively, including everything that pertains to the largest yield and the highest feeding value, the tests favor cutting alfalfa for cattle feeding when the first blooms appear.