GENERAL PROBLEMS IN DAIRY HUSBANDRY 355 



cleansed and the rubber tubing kept in an antiseptic solution, the sani- 

 tary condition of the milk is improved over that ordinarily obtained by 

 hand milking. Owing to the first cost of the machines and the labor 

 involved in their operation and cleansing, various authorities consider 

 machine milking economical under usual conditions only where at least 

 15 to 30 cows are milked thruout the year. 



566. Minor points. Dehorning cows causes a small temporary decrease 

 in milk flow but is repaid a hundred fold in the greater comfort of the 

 herd thereafter. Subjecting cows to the tuberculin test has practically 

 no effect on the yield of milk or fat. Milking three or four times a 

 day may cause a slightly larger flow of milk, but it is not profitable ex- 

 cept with very heavy milkers and cows on official test. 



Contrary to considerable popular opinion, the period of oestrum, or 

 heat, does not generally have any very marked effect on the yield of milk 

 or butterfat. Hooper and Bacon found at the Kentucky Station 45 * that 

 on the average cows gave 0.1 Ib. less fat and 1.5 Ibs. less milk on the day 

 of most evident heat. Several cows were not thus influenced, but on the 

 other hand, a few nervous cows were greatly affected. 



From a study of 1,497 Register of Merit tests on Jersey cows, they 

 report that cows not carrying calves tend to produce slightly more milk 

 in a year than those which are pregnant. 



"Woodward, Turner, and Curtice of the United States Department of 

 Agriculture 46 found that when cows which were immune to tick fever 

 were infested with ticks the milk yield was reduced 34.2 per ct. on ac- 

 count of the depletion of the blood. In tick infested districts they advise 

 spraying or dipping with an arsenical solution, at least when animals are 

 heavily infested. 



567. Flavor, odor, and color. The flavor and odor of milk and its 

 products are highly important. Due to minute quantities of volatile 

 oils they contain, which are the source of the trouble, onions, leeks, 

 turnips, rape, etc., give an objectionable flavor to milk, unless fed im- 

 mediately after milking so that the volatile oils may escape from the 

 body before the next milking. When cows are first turned to pasture, we 

 at once note a grass flavor in the milk and butter, which soon disappears 

 or which we fail to notice later. 



Wild onions and leeks are often troublesome pests in pastures in early 

 spring, causing off-flavor milk. Hooper of the Kentucky Station 47 re- 

 ports that to avoid this cows may be grazed on pasture infested with 

 wild onions for only 2 or 3 hours after milking and kept in a clean pas- 

 ture or paddock 5 or 6 hours before the next milking. Quick cooling of 

 the milk to 41 F. tends to drive off some of the volatile flavor. 



Sometimes when a cow is far along in lactation her milk becomes 

 bitter and distasteful. Eckles 48 states that so far as he has observed, 

 this occurs only when the animal is far advanced in pregnancy and 



"aKy. Bui. 234. "Information to the authors. 



*U. S. Dept. Agr. Bui. 147. ""Dairy Cattle and Milk Production, p. 227. 



