DAIRY FARMING DAIRYING. 767 



Palatability was apparently an important factor in feeding prickly pears as 

 the sole roughage. One cow that ate prickly pear with relish did as well on the 

 ration when that plant was the sole roughage as when some dry roughage was 

 included. Another that ate prickly pear reluctantly lost in weight. In one case 

 feeding prickly pear alone caused the formation of an obstruction in the intes- 

 tine and the death of the animal. The feeding of prickly pear produced a highly 

 colored butter, but had no appreciable effect upon the flavor or keeping quality 

 of the milk. Prickly pear had a decidedly laxative effect on the cows, although 

 there seemed to be no permanent ill effects even after long-continued feeding. 

 The addition of 4 to 6 oz. a day to each cow of common salt had no appreciable 

 effect upon the laxative property of the plant. 



During an experimental period of 10 days cows receiving a heavy ration of 

 prickly pear drank no water, those receiving a medium ration drank an average 

 of 44.3 lbs. of water per day, while those on a roughage ration of sorghum hay 

 drank a daily average of 95 lbs. As measured by milk production, cows fed 

 prickly pear were more sensitive to sudden drops in temperature than those 

 which received a dry roughage. The greater the quantity of the plant consumed 

 the more sensitive the animal became. The prickly pear ration appeared to have 

 no great influence upon the size and vigor of the offspring or upon the condition 

 of the cow after parturition. 



The cost of harvesting prickly pear depends largely upon local conditions. 

 During these experiments it was found that the spines could be singed at a cost 

 of about 50 cts. per ton. 



There was no gi-eat difference between the spineless and the spiny varieties 

 of prickly pear in composition, palatability, or feeding value. While the cost 

 of harvesting the spineless was less than that of the spiny varieties, the latter 

 yielded a greater tonnage to the acre and were not so subject to injury from 

 insects. 



It is concluded that prickly pear is a good and palatable feed for dairy 

 cows. It is best to feed the plant in medium quantities, 60 to 75 lbs. a day 

 to each cow. When fed in large amounts, 120 to 150 lbs. a day, it causes 

 an excessive scouring and a very insanitary condition of the stable. On account 

 of the high content of mineral matter, it is thought that prickly pear may be 

 of special value as a supplementary feed for use with other roughages of a low 

 mineral-matter content, such as cotton-seed hulls. 



Standards for determining the purity of milk. — The limit of error in 

 bacteriological milk analyses, H. W. Gonn (Pub. Health Rpts. [U. fif.], 30 

 {1915), No. S3, pp. 2349-2395) .—The importance of a revision of the standard 

 methods of milk analysis as published by the American Public Health Asso- 

 ciation is ptointed out. This paper gives the results of tests conducted cooper- 

 atively by four of the large bacteriological laboratories in New York City, the 

 tests covering a period of seven months and involving nearly 20,000 separate 

 analyses by a variety of methods. 



It was found that individual analyses under the best conditions are sub- 

 ject to considerable variation, so that no single individual count can be prop- 

 erly relied upon. The question of the exact composition of the media to be 

 used is deemed of far less significance than that of the methods used in the 

 manipulation. 



The need of unifying laboratory methods was demonstrated. There were 

 found to be wide differences in the analyses of duplicate samples, due chiefly 

 to differences in laboratory technique, the more Important being the following: 

 (1) Shaking of the samples. Wide variations were found in the vigor and 

 the extent of the shaking to which the samples of milk and the dilutions are 

 subjected by the different laboratories. (2) Amount of dilution. The counts 



