2 BULLETIN lit; U. S. DEPABTMENT OF AGEICULTUEE. 



by a single tick may be relatively small, but the total amount drawn 

 by thousands of ticks on one cow can not fail to be injurious. If 

 each tick represents but a dram, or a teaspoonful, of blood, a few 

 over 1,000 would represent 8 pounds of blood. It is possible that 

 each tick absorbs more than a dram of blood. 



But the greatest disturbance created by the tick seems to be, 

 not in the amount of blood abstracted, but in the fact that it is the 

 carrier of the germ of Texas fever which it transmits to cattle. 1 

 When cattle that have never become accustomed to ticks are infested 

 they become very sick and usually die. This may occur anywhere, 

 either within or without the tick-infested region. Cattle that survive 

 the ticks usually remain immune to their worst effects afterward. 

 However, as time passes the important fact that no cattle in the 

 quarantined area of the South are ever safe from the effects of 

 Texas fever, either in its acute or chronic form, becomes more and 

 more impressed on those who have to study the affected cattle. 



PLAN OF THE EXPERIMENTAL WORK. 



As the dairy industry is becoming an important branch of southern 

 agriculture it was thought desirable to ascertain the effect of the 

 tick on the milk production and body weights of dairy cows. Twenty 

 grade Jersey cows 2 of about average dairy quality were selected in 

 the early part of their lactation periods. They were in fair condition 

 of flesh at the beginning, and all had been tick infested at some time. 

 The animals being immune to ordinary attacks of tick fever, the 

 results should be applicable to the average dairy herd in the tick- 

 infested areas. These cows were divided into two groups of 10 ani- 

 mals each, the two groups being balanced as nearly as possible in 

 regard to milk and butter-fat production, condition of flesh, and 

 size. One group was freed from ticks by spraying with "tick dip B," 

 an arsenical solution used by the Bureau of Animal Industry hi the 

 tick-eradication work. Data were taken on only nine cows of this 

 group, as one cow received an injury to her udder which stopped 

 her milk flow early in the test. The other group was kept tick- 

 infested by applying seed ticks at regular intervals. The degree of 

 infestation varied with different animals and with the entire group 

 at different times during the course of the experiment. 



The experiment began May 21, 1913, and lasted during a period of 

 140 days. The milk of each cow was weighed and a sample taken 

 at every milking for a composite fat test at the end of each 10-day 



1 Further details concerning the life history of the cattle tick and the protozoan causing the fever can 

 be found in Farmers' Bulletin 258. 



2 The cows and the feed lots used in these experiments were provided by the Anthony Farms Co., 

 Anthony, Fla., of which Mr. E. C Beuchler is manager and vice president. 



