Good parasite control is critical in sheep and goats

It is not just the livestock and the grass that have been growing this spring in response to the un-Texas like rains.

Parasites have been a major cause of death and disease in our small ruminants (sheep and goats) this summer. The two most common parasites in our region are the barber pole worm (Haemonchus contortus) that sucks blood, and Trichostrongylus or Telodorsagia worms that cause diarrhea.

Both types of worms cause weight loss and poor production in a herd or flock. The adult worms live in the stomach and the larvae live on the grass. It takes 21 days for larvae eaten by a sheep or goat to develop into adults and start laying eggs that pass out in the feces. The time it takes for larvae to develop from the eggs and crawl up the grass to about 2 inches (the maximum height that they reach) depends on the weather. Warm wet weather is preferred by the larvae as they use a dew drop to retain moisture during the warm part of the day.

There are only three major groups of anthelmintics (or dewormers) available to kill the worms. Historically, it was recommended that frequent deworming (every month) and rotating dewormers would kill more worms, and prevent dewormer resistance. Unfortunately, this is not the case. Every time we use a dewormer, at most it only kills 95 percent of the worms. This means that 5 percent of the worms are resistant to that dewormer. If the same dewormer is used frequently it does not take very long for the worm population to have enough resistance that the dewormer no longer is effective. Rotating dewormers causes resistance to develop in all of the products used in the same amount of time.

So how do we prevent resistance from developing? The current recommendations are to practice sustainable parasite management. This takes the emphasis away from routine deworming and instead relies on monitoring for worms in the animals themselves. We can monitor for parasites by performing FAMACHA (FAffa MAlan CHArt) scoring, body condition scoring or weighing, fecal egg counts and monitoring fecal consistency.

The goal is to identify those individual animals that are mildly parasitized and treat them before there are major production losses or deaths, and not treat those animals that do not have a high parasitic load. By not treating all animals with dewormer, the sheep and goats that are not treated dilute out any resistant worms on the pasture with susceptible worms. FAMACHA scoring was developed to monitor the level of anemia of sheep with Haemonchus worms. It involves examining the inner eyelid color and comparing it to a standardized chart.

Taken from The Eagle

To read more, Good parasite control is critical in sheep and goats