Part One

by Robert Spencer

By the time you read this article, summer will be half past and you will probably have had your share of parasite problems. However, I felt this set of information is very important for goat and sheep producers to understand parasites are comprehensive management issue and there is no one single answer regarding their control and related complications. The second part of this article will be in next month’s issue.

The discussion in this article offers a brief overview of the parasite management strategies utilized over the years. It is written with the intent to encourage assessment of what might work best for your situation, respecting the fact each farm situation is different. As the heat, humidity and rains of summer set in, so do problems with gastrointestinal worms (stomach worms)! Over the years there have been all kinds of claims being made regarding parasite control, everything from products to strategies for controlling infestation of stomach worms. Their control requires a comprehensive approach.

In extreme situations parasite overload can result in mortality among goats and sheep. Internal parasites affect young and old animals, and can impair animal vigor, potential growth, health and lead to anemia which can lead to mortality. Bottom line, these parasites have an economic impact on farm revenue; whether it is in the form of additional health care costs, lost productivity or animal mortality. Minimizing problems with gastrointestinal worms requires an understanding of methods and mechanisms! A strong knowledge base and appropriate strategies have potential to work, but require frequent evaluation and adjustments as needed. However, the implementation of such a comprehensive set of strategies should be considered as a "total management system." In other words, just one or two strategies will have limited long-term effect and, at the first onset of "bottle jaw" or mortality, leave a producer wondering what went wrong. Over the years, sheep and goat producers have utilized an array of broad spectrum anthelminitics (dewormers); some labeled for small ruminants and some not (off-label), except with the recommendation of a veterinarian. These chemical wormers were used to combat all types of gastrointestinal worms, some more commonly known as brown stomach worm, tapeworm, barber pole worm, etc. Producers were expecting with proper dosage, strategic usage, aggressive treatment and rotational application they could eliminate problems with these prolific parasites. The most troublesome being the barber pole worm (Hamonchus contortus), a highly pathogenic blood-sucking parasite. Over a decade later, it became obvious complete elimination of these parasites was not possible, they were too resilient and were building up tolerances/immunities to various dewormers. Some producers/experts became more aggressive with use of off-label wormers, but to no avail. For more information on the barber pole worm, see Extension publication UNP OO78 Haemonchus contortus (Barber Pole Worm) Infestation in Goats by Dr. Maria Leite-Browning.

Eventually, it was recognized switching dewormers for no justifiable reason was actually accelerating parasites tolerance to chemical wormers. The new recommendation has been to utilize a dewormer until it stops working, then switch to another class of dewormer. But this utilizes another approach that will be mentioned later. Historically, more experienced livestock producers were familiar with two concepts to help control problems with stomach worms: (1) Allow animals to only graze on pastures where forages are taller than six inches. When forage height nears six inches then move animals to another paddock. (2) Utilize a practice known as rotational grazing, putting lactating and young animals in paddocks ahead of the rest of the herd. When properly done, this strategy was known for insuring two things. (1) Lactating and young animals are first to benefit from ungrazed paddocks by allowing them initial access to quality forages. (2) Fresh ungrazed pastures should have minimal presence of gastrointestinal worms; therefore, the most vulnerable animals (lactating and young) would have quality nutrition and minimal exposure to stomach worms. While there are more details to this concept, it works to some extent. (1) It provides quality, high-nutrient forages for those who need it. (2) Paddocks must remain fallow at least 60 days prior to being grazed again, and then parasite presence should be reduced. But that does not mean these paddocks are clean of parasites. Utilized properly this system works and works fairly well, but is not a cure to problems with stomach worms.

Robert Spencer is a contributing writer from Florence.