68 



l)er cent ; in the casein, n gaiu in three cases of 0.02 to O.OG per cent and 

 a loss in one case of 0.09 per cent; in milk sngar, a gain of 0.4 per cent 

 in two cases and a loss of 0.02 and 0.03 per cent in the other two cases. 

 Taking the average of the four lots of cows when the narrow ration was 

 changed to a wide one by substituting corn meal in the place of gluten, 

 ipound for pound, the yields of milk per cow per day were with gluten 

 22.07 pounds, with corn meal 20.2 pounds — loss 1.87 pounds. The per- 

 centages of total solids increased O.IG, of casein O.OG, and of sugar 0.19, 

 while the percentage of fat decreased 0.09. Taking into account both 

 amount and composition of the milk as affected by the change from the 

 wider to the narrower ration, the total amount of butter fat in the milk 

 per day increased ver^- slightly in one case and decreased in three cases. 

 The average amount in the milk per cow per day was with the more nitro- 

 genous ration 0,977 pounds and with the less nitrogenous 0.875 pounds, 

 making a loss of 0.102 ])onnds with the wider ration. '' The average cost 

 of the corn meal rations was $0.]61,of the gluten meal $0,171, per day. 

 And with the eight cows under consideration the cost of milk per cwt., 

 with the gluten, was $0,774; with the corn meal, $0,797; a difference 

 of $0,023 per cent in favor of gluten." To recapitulate briefly, in these 

 experiments when the nitrogen of the food was diminished and its non- 

 nitrogenous ingredients increased the total milk yield was decreased. 

 The ])ercentage of total solids in the milk increased in every case ; the 

 percentage of casein in the milk was increased in three trials out of four 

 and in the average of all four; the percentage of fat and the total amount 

 of fat in the milk decreased in the same three cases out of four and in 

 the average of all. It should be added, however, that the change in 

 composition of the milk was in some cases so small as to approach the 

 4imits of error of analysis. 



Effect of narrow and wide nutritive ratios on the ratio of casein to fat 

 ■in millc. — A number of further observations on the effect of food upon 

 the ratio of casein to fat in milk are given. A Jersey and two Short- 

 ihorn cows received rations with nutritive ratios varying from 1 : 5.5 to 

 1 : 12.3 during periods of fourteen days each. In the results' obtained 

 in 29 periods there was in general somewhat more casein in proportion 

 to the fat with the non-nitrogenous than with the nitrogenous food. In 

 brief, so far as these results are concerned, the effect of reducing the 

 proportion of protein and increasing the non-nitrogenous constituents 

 of the food was to increase rather than diminish the ratio of casein to 

 fat. It is to be noted, however, that the range in the rations fed was 

 from what is commoidy regarded as normal to a large excess of carbo- 

 hydrates. The (German) standard for milch cows, which is commonly 

 <]UOted, has a nutritive ratio of 1: 5,4, which is about that of good pas- 

 ture grass. The effects of excess of protein in the food were not tested. 



^^ Butter and cheese cows. " — Attention is called to the error in suppos- 

 ing that milk that is i)oor in fat is rich in casein or that " poor butter 

 cows are great cheese cows. " In general a high percentage of fat and 



