BeefTalk: Parasites, the unwanted guest
Beef Specialist, NDSU Extension Service
I was watching a video of what appeared to be a wiggling thing inside a very small sack. The wiggling thing was actually a small parasite larva inside the egg sac attached to a small blade of grass. The larva was about to hatch.
Some time has passed since I watched the video, but the concept of parasites has not changed. Parasites are something that make a living off others. Parasites are not a problem of just one type of animal, but all living things. Sometimes parasites can exist without even affecting the host, but other times they can be fatal to the host.
I was reminded of this video because the Dickinson Research Extension Center utilizes sheep for small-pasture grazing on the center’s replicated agronomy plots. The sheep were starting to show signs of parasitism; their feces where quite loose, with some even starting to show evidence of diarrhea.
With my background of raising sheep, I was reminded of how sheep producers can get caught in a parasite trap when raising sheep. Sheep are more sensitive to parasite infestation than some of our other domesticated species and are quick to manifest the symptoms of parasite infestation.
Sheep producers always need to be monitoring their flock and implementing an aggressive parasite control program. More times than not, when a sheep producer experiences general un-thriftiness in the flock, parasite control should be the first response.
Although the sheep sensitivity to a parasite infection served as a reminder to me to implement a parasite control program for the center’s sheep, the sheep actually reminded me of the need for producers to keep a constant vigil of all that is going on around the ranch. The question producers often find themselves asking is, “Why now?”
The answer probably was evident in the subtle workings of the ranch at some time prior to the actual problematic outbreak. If we use parasites as an example, all parasites have a rather defined life cycle, a life cycle that often includes an external and internal component. Regardless of what parasite, timely managerial intervention that is based on the life cycle of each parasite and seasonal cycles of the host is critical.
Although I am using the sheep as an example, cattle also are hosts to parasites, and the general principles are no different. Each parasite/host relationship is different, requiring a broad understanding of the relationship, as well as a professional relationship with a herd health consultant.
In simplistic terms, the issue, and the reason for this article, was a sheep’s response to the season this year. This year, bountiful moisture, moderate temperatures and ample forage set in play many life cycles. If you watch the numerous documentaries on interesting animals and insects or other life forms, you will see that many come to life with rain after months, if not years, of inactivity. When Mother Nature provides moisture, many life forms engage.
That is true of parasites as well. As noted earlier, many parasites require a period of time outside of the host. Eggs are passed out of the host via the feces. These eggs may very well do nothing if the weather is not appropriate for development.
A side note: Growing up on a farm or ranch that involved many types of plants and animals certainly taught many young minds the diversity of life and how each week, in different seasons, brought different challenges. The bad always came with the good. The managerial question was sorting the difference and ending the season with more good than bad.
Anyway, many parasites are no different. When all is good for the grass to grow and calves to gain, the armies of weeds, parasites and other very small life forms also will take advantage and grow as well. Unfortunately, with parasites, when the external environment is ideal for their eggs to hatch, they can and will overwhelm the host.
Young calves and lambs are more susceptible because they have not developed immunity to the many biological pathogenic invaders that constantly challenge all living things. A good point to keep in mind, just as the ewe or cow seeks out good pasture for the summer, is that parasites always are seeking out a good host for the summer.
Yes, natural immunity is required for long-term survival, but as producers, you have managerial interventions that will handicap the parasite population and keep parasite impacts on health at bay.
As producers, when times are good and forage seems ample, always keep in mind the need to monitor parasites. One egg and a nice damp blade of grass can make for a troublesome meal for a young calf or lamb.
May you find all your ear tags.
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