884 EXPERIMENT STATIOK RECORD. 



a small part of the ration for dairy cows. Potatoes are ot to be recommended. 

 Carrots are superior to beets, but the increased yield of butter due to carrots is not 

 sufhcient to pay for the cost. Oats and wheat l)ran are satisfactory feeds. Horse 

 beans are not suitable for butter production. Malt sprouts and 1 )rewery residue may 

 enter into the dairy ration, the latter to be fed with concentrated feeds. Sugar-beet 

 pulp, well ensiled, may be fed without inconvenience to the animals and without 

 bad effects on the quality of milk and butter. Of the oil cakes, cotton seed, cocoa- 

 nut, linsee<l, sesame, colza, and poppy rank in the order named. 



Danisli experiments on the feeding of dairy cows, A. Mallevre (.4m?. Inst. 

 Nat. Agron., 24 {1897-1900), No. 16, jrp. 217-240). — This is a review of investigations 

 in Denmark on the feeding of dairy cows based largely on reports of the la])oratory 

 of agricultural experiments of the Royal Veterinary and Agricultural High School of 

 Copenhagen. Methods employed in feeding experiments with dairy cows are 

 described in detail, and resmnes are given of experiments on the addition of root 

 crops to ordina. y rations for dairy cows, the substitution of root crops for concen- 

 trated feeding stuffs, and the effect of root crops on the quality of butter. 



The physiolog'y of milk secretion, A. W. Bitting {Indiana Sta. Rpt. 1901, 

 pp. 51-88). — The author discusses this subject in detail under the following headings: 

 The characteristics of milk, quantity and quality of milk secreted, influences affecting 

 milk production, influence of food upon milk secretion, and comjiarisons of grains 

 and by-products. The article includes compiled data relating to the composition 

 and properties of milk and a review of considerable experiment-station work. 



Different theories of milk formation are given. "The latest theory is to regard 

 milk as a product of metabolism of the cells of the mammary gland. It is in all 

 essential characters a secretory product, and not an excretory product. In reviewing 

 the physiology of the formation of milk in such a light, it is only regarding it in the 

 sam(! way as saliva, gastric and pancreatic juices. It may be argued that these glands 

 secrete a special product to be used in the animal economy, while milk is not so used. 

 All excretory glands, as the kidneys, liver, and sweat glands, find their material 

 already prepared in the blood, the result of activity in other parts of the body, and 

 they serve as a means of eliminating it. Secretory glands, as the pancreas, salivary 

 glands, etc., do not find their active principles in the blood, but construct them within 

 their own especial cells. The mammary gland does not find fat, casein, and lactose 

 in the blood, but con.structs them within its own tissues. The recognition of the 

 mammary gland as an organ having a special function will explain fully all the diffi- 

 culties met in trying to reconcile all other theories with the facts as they are 

 observed." 



Under the influences affecting milk pro<luction are considered breed, heredity, 

 age, pregnancy, and food. In this connection are given brief summaries of the 

 results of experiments at a number of stations considered typical of the work done 

 to determine the effect of food upon the (juantity and quality of milk. "In all cases 

 the influence is within narrow limits, and can all probably be accounted for by the 

 general effect upon the Vjody, or by one food l)eing more palatable than another and 

 therefore more agreeable to the animal. The effect upon milk is probably no greater 

 than it is upon the body as a whole The discrepancy between the results obtained 

 by different experimenters may often be accounted for by the difference in the 

 method of conducting the experiments. The usual length of time given to each 

 period in a feeding experiment is 10 days or 2 weeks. Many foods have a temporary 

 stimulating effect, which food naturally shows in such short period experiments, and 

 which would disappear if the period were continued for a longer time." 



The author also di.scusses milk secretion as affected by drugs, certain foods con- 

 taining volatile substances, watering, weather conditions, methods of milking, exer- 

 cise, excitement, abortion, sickness, tuberculin, dehorning, and spaying. 



