288 A TICK -RESISTANT CONDITION IN CATTLE. 



The iiiajoi'ity of cattk' owners who have interested them- 

 selves in any way in this subject, are of the opinion that 

 dipping makes no difference ; but several persons in the 

 South Coast district. hoAvever, hold with Mr. Hull, that the 

 effect of dipping is to induce an animal to carry ticks. 



Information obtained by us from Mr. Henderson 

 (R.S.C., 1915, p. 41) was to the effect that a coav which had 

 become resistant after vaccination relapsed to a tick}' con- 

 dition three years later. This animal had been dipped but 

 Mr. Henderson was not prepared to saj* whether loss of 

 resistance Avas. or AAas not, due to dipping. 



Actual facts observed by us seem to be overwhelmingly 

 in favour of the view that dipping has no appreciable effect 

 on resistance. In February, 1918, Mr. Fred Hull undertook 

 to dip regularly one of his clean cows — Daphne ; in June 

 last she Avas still free from ticks. In almost every herd 

 examined a few (1-8) tick-resistant animals Avere noticed. 

 These are usually put through the dip with the rest of the 

 cattle, cutting out individual animals giAing too much 

 trouble, while in cases where a dip is not used and spraying 

 or washing is resorted to, resistant aniiAals are treated 

 if ticks are noticed on them, Avithout apparent diminution 

 of their tick resisting property. 



The experience of Messrs. Jones and Jenner, of Croham- 

 hurst district, both of Avhom have a large number of 

 resistant animals Avhich are occasionally treated Avith an 

 arsenical solution, supports this A'iew. 



Persistence of Resist.ince. 



Tick resistance may be lessened by (1) low condition 

 brought about by drought or prolonged milking and poor 

 feed, (2) by subjection to unnatural conditions, e.g., stalling 

 and rugging. In animals liAing under faA^ourable con- 

 ditions, i.e., as regards food and Avater, resistance raa.y 

 persist from birth, or from Avhatever time the animal acquired 

 such resistance. Strongly resistant animals may, if able 

 to maintain their condition, withstand tick infestation 

 €A^en during unfavourable circumstances. 



On February- 11th, 1910, Mr. Hull reported that tAvo 

 days preA'iously he had brought in 28 head of cattle from 

 relief country, where they had been running for three months 



