FEEDING STANDARDS— CALCULATING RATIONS 97 



Feed consumed Lbs. for 1 unit Feed units 



240 lbs. hay ^ 2.5 z= 96 



750 lbs. silage H- CO = 125 



120 lbs. corn and barley -f- 1.0 — 120 



90 lbs. oil meal -^ 0.9 — 100 



Total feed units = 441 



It is shown that the cow consumed 441 feed units during the month. 

 If in that time she yielded 850 lbs. of milk, containing 30.6 lbs. of fat, 

 each 100 feed units produced :^= 193 lbs. of milk, containing ^= 

 6.9 lbs. butter fat. If the fat brought 30 cents per pound, 100 feed 

 units would return 6.9 X $0.30 = $2.07. Similar comparisons pf the 

 economy of production of various cows and herds may be made on the 

 basis of the therms of net energy or the pounds of total digestible 

 nutrients consumed.^ 



V. American Standards for Dairy Cows 



The Haecker standard.— As the result of long years of study at the 

 Minnesota Station,* Haecker has made an important advance in the 

 computing of rations for the dairy cow. He has shown that the nutri- 

 ents required for her nourishment should vary not only with the quan- 

 tity of milk yielded, as is taught in the standards previously discussed, 

 but also with the quality of the product. The allowance of crude pro- 

 tein recommended is also considerably lower than that set forth in the 

 AVolff-Lehmann standard. In his standard Haecker first sets down the 

 total digestible nutrients daily required to maintain the 1,000-lb. cow, 

 independent of the milk she produces, as follows : Crude protein 0.7 lb., 

 carbohydrates 7.0 lbs., and fat 0.1 lb. For each 100 lbs. live weight the 

 cow may exceed or fall below the 1,000-lb. standard there is added or 

 subtracted one-tenth of the standard ration. 



To this maintenance provision the further allowance set forth in the 

 table is added. 



a Hansson has proposed the following feeding standard for dairy cows accord- 

 ing to the feed unit system. This is not of niucli interest to American dairymen, 

 however, for it is less accurate than the standards of Haecker, Savage, or Eckles, 

 which are described later, and which recognize the important fact tliat the feed 

 requirements of dairy cows depend not only on the quantity but also on the 

 richness of their milk. 



For maintenance, feed 0.65 lb. digestible protein and 0.6 feed units daily per 

 1,000 lbs. live weight. 



For each poimd of milk produced add to the maintenance requirement 0.045 

 to 0.05 lb. digestible protein and 0.33 feed unit. 



4 Minn. Buls. 71, 79, 130, 140. 



