Manual dipping vat agitation is 

 strenous work. Air agitation 

 assists in mixing the dip, but no 

 device replaces the bottom scraping 

 of the vat to resuspend the sediment. 

 Sufficient time must be spent 

 agitating the vat; a minimum of 30 to 

 45 minutes of hard work is necessary 

 to agitate a large dipping vat. Once 

 agitation is completed, dipping the 

 livestock must proceed rapidly or the 

 vat contents will begin to settle. 



The pesticide's effectiveness is 

 impaired by pollution of the dip by 

 clay, dirt, manure, urine, hair, 

 etc., carried in by the animals being 

 dipped. The relationship between 

 pollutants and the pesticide will 

 vary with the chemical and the type 

 of formulation. "The settling rate 

 for a suspension is directly related 

 to the type of formulation, age of- 

 the dip, and degree of pollution." 

 "Wettable powder formulations, like 

 all dips are eventually reduced in 

 efficiency by pollutants which, as 

 they increase in quantity, virtually 

 smother the insecticide's 

 effectiveness" . 



Density, temperature and chemical 

 reaction between pollutants and the 

 pesticide are factors causing 

 layering to take place in the dipping 

 vat. Agitation is more difficult if 

 layering has occured. 



The dipping vat design may be such 

 that agitation is necessary while the 

 cattle are being dipped. "In the use 



of wettable powder with poor 

 suspendability, often 10 to 15 

 percent of the active ingredient is 

 lost at the very beginning of a 

 dipping operation. The pesticide is 

 deposited at the "jump-off" end of 

 the dipping vat where the dipping vat 

 is deepest and where an eddy is , 

 created in the dipping process." 

 Adequate agitation in the area of 

 the eddy will alter the 

 eddy currents and reduce or prevent 

 pesticide deposits. The eddy 

 phenomenon is one reason vat samples 

 are reported from the laboratory 

 with low concentrations even after 

 large numbers of cattle have been 

 dipped. It is not possible to 

 satisfactorily agitate a dipping vat 

 by swimming cattle through it, nor 

 is adequate agitation always 

 maintained during the dipping 

 process. 



Federal standards have been 

 established for pesticide dipping 

 concentrations, dip sedimentation 

 rates, the number of cattle that can 

 be dipped per gallon of vat content, 

 and the length of time the vat 

 contents may be used. These 

 standards, formulated to function on 

 a program basis, are practical, 

 since they are based on field 

 program studies and controlled 

 laboratory research. It is 

 generally accepted that in the 

 United States , the high standards 

 established have prevented the 

 development of tick resistance to 

 pesticides. 



, The 



Asuntol Story, Bayer, Leverkusen, 

 Germany, Veterinary Department, 

 p. 15. 



3 

 Ibid, p. 14, 



Carson, Nathan, B. , unpublished 

 presentation given to Tick Technical 

 Meeting, Kerrville , Texas, March 6, 

 1980, "Phenomena Which Adversely 

 Impact the Objective of Optimum 

 Pesticidal Activity in Dipping 

 Vats." 



