914 EXPERIMENT STATION RECORD. 



It should also be borne ill mind in experiments with ruminants that 

 the nitrogenous extractives serve as protectors of protein, and hence 

 have a value greater thau that indicated by their heat of combust ion. 

 Weiske, Meier under the writer's direction, and later Kellner have 

 shown that with ruminants asparagin serves as a protector of protein. 

 The most reasonable explanation is that the bacteria which cause fer- 

 mentation in the intestinal tract use amid bodies as a nutrient in place 

 of protein. If there is an abundance of amids present the bacteria 

 use little protein, and when the supply of amids is limited protein 

 which would have served for the needs of the body is utilized. The 

 micro-organisms form protein from amid nitrogen by using it, together 

 with carbohydrates, as a source of energy for the formation of cell 

 plasma. They die and are eventually digested, and thus the body 

 gains protein formed from amids. 



Closely connected with the foregoing is the so called depression of 

 digestion. If a large quantity of starch or feeding stuffs rich in 

 starch is added to the food of ruminants it has been observed that 

 the digestibility of the nutrients, especially of protein and crude 

 fiber, is diminished. If sufficient protein is added to the normal ration 

 plus starch, the digestibility of the nutrients again becomes normal. 

 This is undoubtedly explained by the fact that the bacteria in the 

 stomach of ruminants serve to render the crude fiber soluble. When 

 an abundance of starch is present they attack this, breaking down the 

 starch molecules and leaving an equivalent quantity of crude fiber 

 unchanged. In other words, many cell walls are not acted upon, and 

 the digestive juices can not reach the cell contents. It is clear, 

 therefore, that diminishing the digestibility of crude fiber must also 

 diminish the digestibility of protein and fat. However, when protein 

 is added to such a ration, or, as Kellner has recently pointed out, 

 asparagin or ammonium acetate, the bacterial action is greatly 

 increased and the digestibility of the crude fiber becomes normal. 



CALCULATION OF RATION FOR A COW WITH CALF. 



In calculating a ration for a pregnant milch cow, a number of sup- 

 positious are necessary. The ration for such a cow 4 months with 

 calf, weighing 600 kg. and producing 12 kg. of milk daily, containing 

 4 per cent of x>rotein, 5 per cent of milk sugar, and 3.5 per cent of fat, 

 must be so adjusted that the general condition of the animal remains 

 unchanged ; that is, the ratio of fat to lean in the body, etc. The cow 

 requires the nutrients for the formation of milk and for the unborn 

 calf. On the supposition that, as the fetus increases in weight the 

 milk yield diminishes, the amount of nutrients required by the fetus 

 at any time — when 3 months old, for instance — can be calculated. A 

 new-born calf weighs about 40 kg. The body contains about 20 kg. of 

 water, 2.5 kg. of mineral matter, 1.5 kg. of fat, and 10 kg. of protein, 

 including the proteid bodies in horn, hoofs, etc. This quantity of pro- 



