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Parasite control in Uruguay

Dr Sergio Fierro, Uruguayan Wool Secretariat
Dr Sergio Fierro, Uruguayan Wool Secretariat

by Sergio Fierro

August 2018

My name is Sergio Fierro, I am a Vet that works in the Uruguayan Wool Secretariat (SUL: www.sul.org.uy), a technical institution, founded, financed and directed by sheep farmers since 1966. My activities are related to technology transfer – extension, technical services and research, mainly in sheep health and reproduction. During the next two months I am going to be in Australia (NSW and Tasmania), sponsored by the University of New England, in subjects related to sheep health. These activities are funded partially by a Training Type Mobility Scholarship from the National Research and Innovation Agency in Uruguay (ANII), partially by SUL and by me.


Secretariado Uruguayo de la Lana (SUL)
Secretariado Uruguayo de la Lana (SUL)

Uruguay environment

Uruguay is a country located on the east coast of South America, between Brazil and Argentina and situated between the 30 and 35 degree lines of latitude, that approximates with the region between Armidale NSW and Canberra ACT. The average temperature range is between 12.9 to 22.6°C with a rainfall average about 1300 to 1500 mm per year, mainly during autumn and spring (with a high variability between years).


Major parasites of sheep

Nowadays the sheep population is around 6.5 million; sheep and cattle graze together, generally on native pastures. These weather conditions give a good environment to the development of sheep worms and the screwworm fly that are major parasites of sheep in Uruguay.

Barber´s pole worm (Haemonchus contortus) is the major worm problem, present all the time during the year, decreasing in winter, when Trichostrongylus colubriformis increases.

To avoid being reactive when outbreaks occur; the worm control system is based on an Integrated Parasite Management program.


Chemical  Control

Non-chemical Control

Strategic drenches: before mating and lambing, at marking and weaning

Grazing management: low worm-risk paddocks for lambing ewes and weaners

Tactical drenches: based on faecal worm egg counts (FWEC), clinical signs, postmortem examination and epidemiological data

Nutritional management: protein supplementation

 

Genetic selection against Haemonchus contortus: using rams with negative breeding values for FWEC


The screw worm fly. Not so different from Australian blow flies.
The screw worm fly. Not so different from Australian blow flies.

Due to the risk of anthelmintic-resistance, we recommend the use of high efficacy drenches (determined by drench resistance test) and non-chemical control is recommended to be used as much as possible.

The Screwworm (Cochliomyia hominivorax) is another issue that affects a range of livestock species. The fly lays its eggs on any fresh lesions and the development of the maggots cause different grades of lesions. Chemical control is used in response to the presence of a lesion or a strike.

It is important to be careful with the sheep flock to avoid causing injuries during handling and to treat affected animals as soon as possible. Due to that, some management (e.g. time of lambing, lamb marking, shearing, etc) is needed to be done only in the times when the fly is not present and this can sometimes result in a less than optimal timing of these operations. Currently, several trials are being carried out to start a national plan for eradication.


Dr Sergio Fierro instructing veterinarians in sheep foot health in Uruguay
Dr Sergio Fierro instructing veterinarians in sheep foot health in Uruguay
Uruguay is on the east coast of South America, between Brazil and Argentina.
Uruguay is on the east coast of South America, between Brazil and Argentina.