Modern experiments (principally German) have resulted in formulating standard rations for different animals at different ages and under different conditions. These feeding standards are only approximate guides, but they are sufficient for practical purposes.

Computing by Energy Values

A method is proposed of calculating feeding requirements, reckoned on the protein and the energy values or therms of chemical energy. A therm is the heat required to raise the temperature of 1,000 kilograms of water 1° C. The chemical energy contained in anthracite is 3.583 therms per pound. (A pound of anthracite produces heat enough to raise the temperature of 3.583 kilograms of water 1° C.) In the same way the amount of chemical energy contained in many feeding stuffs has been measured. Following are determinations of chemical energy in 100 pounds (with 15 per cent moisture): —

 Therms Therms Timothy hay..... . 175.1 Corn-meal.......... 170.9 Clover Hay...... 173.2 Oats............... 180.6 Oat Straw 171.0 Wheat bran............ 175.5 Wheat straw................ 171.4 Linseed-meal......... 196.7

Maintenance requirements of cattle and horses, per day and head (Armsby)

(Production requirements are also determined, and must be used in calculating rations.)

 Live Weight Cattle Horses Digestible protein Energy value Digestible protein Energy value Pounds Pounds Therms Pounds Therms 150 0.15 1.70 0.30 2.00 250 0.20 2.40 0.40 2.80 500 0.30 3.80 0.60 4.40 750 1000 0.40 0.50 4.95 6.00 0.80 1.00 5.80 7.00 1250 0.60 7.00 1.20 8.15 1500 0.65 7.90 1.30 9.20

Computing on Basis of Quality and Quantity of Milk

"The quality of milk is quite as important a factor in formulating a feeding standard or guide to feeding practice, as quantity of milk yielded," according to Haecker (Minn. Bull. 79). "It would seem quite as consistent to feed an animal food regardless of its composition as to feed an assumed ration regardless of the composition of the product which is to be elaborated from the nutrients of the food."

It is probably not possible to ' feed fat into milk," provided the animal is otherwise well nourished, but the Haecker standards are not founded on that idea, but on the assumption that the greater the yield of butter-fat the greater should be the feed of maintenance. This method is sometimes used instead of the German method (p. 413), in figuring rations for dairy cows.

Net nutrients used by mature cows for the production of one pound of milk testing a given per cent butter-fat (Haecker)

 Protein Carbohydrates Ether Extract Milk testing.......... 2.5 .0362 .164 .0124 " 2.6 .0369 .167 .0126 " .......... 2.7 .0376 .171 .0128 " 2.8 .0383 .174 .0131 " 2.9 .0390 .177 .0133 " 3.0 .0397 .181 .0136 " .......... 3.1 .0404 .184 .0138 " 3.2 .0411 .187 .0140 " 3.3 .0418 .190 .0142 " 3.4 .0425 .194 .0145 " .......... 3.5 .0432 .197 .0147 " 3.6 .0439 .200 .0149 " 3.7 .0446 .204 .0152 " .......... 3.8 .0453 .207 .0154 " .......... 3.9 .0460 .210 .0156 " 4.0 .0467 .214 .0159 " .......... 4.1 .0474 .217 .0161 " 4.2 .0481 .220 .0163 " 4.3 .0488 .223 .0165 " 4.4 .0495 .227 .0168 " 4.5 .0502 .230 .0170 " 4.6 .0509 .233 .0172 " 4.7 .0516 .237 .0175 " 4.8 .0523 .240 .0177 ".......... 4.9 .0530 .243 .0179

Net nutrients used by mature cows — Continued

 Protein Carbohydrates Ether Extract Milk testing.......... 5.0 .0537 .247 .0182 " 5.1 .0544 .250 .0185 " 5.2 .0551 .253 .0187 " 5.3 .0558 .256 .0189 " 5.4 .0565 .260 .0192 " 5.5 .0572 .263 .0194 " 5.6 .0579 .266 .0196 " 5.7 .0586 .270 .0199 " 5.8 .0593 .273 .0201 " 5.9 .0600 .276 .0203 " 6.0 .0607 .280 .0206 " 6.1 .0614 .283 .0208 " 6.2 .0621 .286 .0210 " 6.3 .0628 .289 .0212 " 6.4 .0635 .293 .0215 " 6.5 .0642 .296 .0217 " 6.6 .0649 .300 .0219 " 6.7 .0656 .303 .0222 " 6.8 .0663 .306 .0224 " 6.9 .0670 .309 .0226 " 7.0 .0677 .313 .0229 Coefficients for food of maintenance1 per cwt. .07 7.7 .01

" Given the daily yield of milk in pounds, its percentage of butter-fat, and the weight of the cow expressed decimally, it is an easy matter to determine the required ration. As an illustration, suppose a mature cow weighs 825 pounds, gives 20 pounds of milk daily testing 4 per cent butter-fat. One pound of 4 per cent milk requires of protein .0467, carbohydrates .214, and of ether extract .0159; multiplying these factors by 20 it is found that for the production of milk the cow needs .934 of protein, 4.28 of carbohydrates, and .318 of ether extract. For food of maintenance, multiply .07 protein, .7 carbohydrates and .01 of ether extract (maintenance* formula) by 8.25, which gives protein .578, carbohydrates 5.78, and ether extract .082; adding to this the nutrients required for milk production, we have 1.51 of protein, 10.06 carbohydrates, and .40 ether extract, the nutrients required in the ration. They should be supplied in such manner with reference to bulk that the ration will satisfy the appetite. A ration like this should be largely made up of roughage." (Haecker.)

For a cow weighing 850 pounds and yielding 40 pounds of 4 per 1 Maintenance standards not detailed here.

Computing The Ration For Farm Animals cent milk daily, the required ration would be (P = protein; C. H. = carbohydrates): —

A ration like this should be largely composed of grain so that it will not contain so much bulk that the cow will go off her feed, and yet furnish the nutrients required. Cows do not require a uniform nutritive ratio, but the ratio varies according to the quantity of milk and weight of cow. To illustrate, let us suppose a cow weighing 1200 pounds and yielding 20 pounds of milk daily, and one weighing 850 pounds yielding 40 pounds of milk, both testing 4 per cent fat: