314 A TICK-RESISTANT CONDITION IN CATTLE. 



Many cattle become habituated to tick infestation 

 and this, in individiial cases at least, leads to some degree 

 of resistance. Such resistance is probabl}^ due to the for- 

 mation of anti-tick poison bodies by the blood of the animal. 



Tick resistant cattle arc known from a number of 

 Queensland localities. Asiatic breeds are tick resistant. 

 Of the various breeds commonly met "with in this State, 

 Jerseys appear to be less affected than others by ticks. 



Tick resistance seems to be influenced by food only in 

 so far as the latter affects the general health of the animal. 



The effect of the application of arsenical solutions 

 to resistant cattle has not been satisfactorily determined. 

 Perhaps the use of arsenical solutions prevents the realis- 

 ation of such resistance. 



Tick resistance persists, provided the resistant animal's 

 health be maintained. 



The temperature of resistant animals appears to be 

 normal. 



There is good reason to conclude that the resistant 

 tendency is hereditarily transmissible. 



Although there is considerable positive evidence of 

 the transmissibility of resistance by vaccination, we have not 

 succeeded in proving it. 



In many cases the condition has been acquired naturally. 

 We think that habituation is a step towards resistance 

 which seems to us to be a physiological reaction to the 

 introduction of a tick toxin. 



The comparatively few ticks which mature on resistant 

 cattle appear to have their fertility, as a rule, somewhat 

 impaired. 



Associated with tick resistance in many animals is an 

 exudation of a lymph-like substance on the skin. This 

 condition is quite distinct from the typical tick sore, though 

 it is apparently a response to tick attack. 



In conchision, we desire to express our appreciation 

 of the assistance we have received from many individuals 

 whose experiences have been quoted in our paper ; the 

 Under Secretary, Department of Agriculture, Queensland, 



