1918] DAIRY FARMING DAIRYING. 779 



had no bad effect on the general condition of the cows, nor was there any 

 perceptible decrease in their live weight. 



Mineral metabolism of the milch cow, E. B. Forbes {Mo. Bui. Ohio Sta., 

 S {1918), No. 1, pp. S-10). — A brief report is made of results secured in the 

 third experiment of this series of studies (E. S. R., 37, p. 169), together with 

 suggestions to dairy farmers upon the importance of legumes in feeding for 

 heavy milk production. 



The rations used in this experiment consisted of alfalfa as a sole roughage, 

 with corn, cottonseed meal, linseed meal, and wheat bran. In certain periods 

 the rations were supplemented by large amounts of calcium lactate, calcium 

 chlorid, and precipitated bone Hour. The cows almost invariably gave off more 

 calcium, magnesium, and phosphorus in milk and excreta than was consumed 

 in the feed. It was impossible by any of the means employed to prevent 

 entirely this loss of minerals. 



Results of investigations upon the causes of the limited capacities of cows 

 to utilize mineral nutrients indicate that this was not due to lack of proper 

 proportion among these nutrients, nor to deficiency of common salt, from which 

 is formed the hydrochloric acid of the gastric juice, nor to difficult solubility 

 of the supplements used, since even the water-soluble calcium lactate and 

 calcium chlorid were poorly utilized. The limiting factor, it is thought, is in 

 the process of assimilation of the mineral nutrients by the bones. 



" It is true that most of the losses of minerals observed were small in com- 

 parison with the extent of the cow's mineral stores ; and that these overdrafts 

 would doubtless be repaid later in the period of lactation when the milk flow, 

 and therefore the draft upon the mineral reserves of the skeleton would have 

 become sufficiently reduced, provided the conditions of feeding were favorable. 

 Still the facts as demonstrated are considered to be practically significant in 

 relation to the frequent failure of heavy-milking cows to breed, to the shrink- 

 age of milk production coincident with advance in the period of lactation, and 

 to malnutrition of the bones. 



"Aiuong other facts of general significance which were observed was the lack 

 of a close relation between the nitrogen of the body and the minerals of the 

 bones in their metabolism. Bone starvation may proceed for some time before 

 it seriously affects the gToss body metabolism. In general it appears that 

 the character of the body metabolism is highly variable ; the organism does not 

 gain and lose in each of its constituents at proportional rates, but rather it 

 exhibits a remarkable degree of metabolic adaptability." 



Simple problems concerning- the fat secretion of milk glands, H. Isaach- 

 SEN {Nor.sk Vet. Tidsskr., 29 {1917), No. Q, pp. 165-178, figs. 7).— In experi- 

 ments here reported, involving four cows, one cow was slaughtered before 

 milking, another after milk had been abstracted by means of a catheter, the 

 third after having been partly milked, and the fourth after having been milked 

 dry. Samples of the milk glands were taken immediately after slaughtering 

 for microscopic examination. In the living cows part of the milk gland was 

 removed by harpooning. 



Microscopic examination showed that the milk glands from cows that were 

 not milked or vrhich had only been tapped for samples contained large, extended 

 alveoli and alveolar ducts. The epithelial cells were full of fat drops. In 

 samples of milk glands from cows that were milked dry, showing many smaller 

 alveoli, the alveolar ducts were much broader and there were no fat drops in 

 the epithelial cells. Milk glands from cows milked half dry showed smaller 

 alveoli, and the fat content of the epithelial cells was less than of those from 

 cows which had not been milked. 



