M.A. Snyman, P.T. Letsoalo#, J.N. Snyman & M. van Heerden

Grootfontein Agricultural Development Institute, Private Bag X529, Middelburg (EC), 5900, South Africa

#Corresponding author: Thomas Letsoalo


Background: Lice infestation has a major impact on the production of mohair in South Africa. Up to 25% less mohair could be produced due to lice infestations. The common practice used by farmers to treat their goats for lice infestation is application of pesticides. When treating goats with pesticides, the problem arises with the residue in the hair after the goats have been shorn. Another cause of concern is the fact that the pesticide washed out of the hair during processing and becomes part of the effluent water that may be pumped back into the environment and cause damage to the environment. It was found that three months after dipping, the amount of residue in mohair still remained above the accepted levels set by the EU Ecolabel and OEKO-TEX® Standard 100.


Aim: The aim of this study was to observe if the effectiveness of two pour-on pesticides in killing lice will be affected when the pesticides are applied at only the ears and tail, compared to the backline of Angora goats with three months’ hair growth and Angora goats that were just shorn.


Methodologies: Twenty-four 4-year old Angora goats, which had not received any pesticide treatment for 8 months, were used in this study. The animals were divided into 8 groups in such a way that the pre-treatment lice count did not differ between the application sites (ears and tail or backline) within hair lengths (long and short hair) and pesticides (Pesticide T - insect growth regulator, and Pesticide W - contact, synthetic pyrethroid). This means that the Pesticide T-ears/tail application-short hair group and the Pesticide T-backline application-short hair group had the same start lice count. The same applied for the other groups. Pesticide T and Pesticide W were applied at the recommended rate of the manufacturers. Live lice were counted weekly at ten predetermined sites over the body for an 11 week period.


Results: With both Pesticide T and Pesticide W lice counts in all groups were reduced within the first seven days. There was no difference in effectiveness of either pesticide whether it was applied along the backline, or only at the ears and tail. Furthermore, lice counts at all the counting sites over the body decreased. For Pesticide T, the long hair animals had significantly more lice than the shorter hair animals, while there was no difference in lice counts between long and short hair animals in the Pesticide W groups.


Discussion: It was found that the effectiveness of both pesticides was not affected when the pesticide was applied at the alternative sites. The contact pesticide was equally effective in long and short hair animals, while it seems that the insect growth regulator was more effective when applied to short hair animals.


Conclusions: Using a contact pesticide, this alternative application method could be used in the mohair industry when farmers are faced with the problem of lice infestation in their goats less than three months prior to shearing. Taking into account a possible loss of 25% in mohair production, combined with a decreased quality, farmers cannot afford to leave lice infestations untreated.



Proc. 50th Congr. S. Afr. Soc. Anim. Sci. Port Elizabeth, September 2017