Decisions regarding parasites

Regular readers will recall that last year was what I called “the perfect storm for parasites” when our mild winter in 2015/2016 turned into a warm and wet spring and summer in 2016, allowing the internal parasites that all sheep normally carry to bloom in our fields, infecting our sheep at never-seen-before levels. Our ewes bred last fall with fewer lambs as a result. We were thrilled when the grazing season finally ended, and we could deworm the entire group and look forward to several months of relief, not having to worry about the symptoms of parasites in our flock.

The problem has not gone away, however. Although our sheep are now carrying very small numbers of these internal parasites – and the lambs are still clean, since none of our sheep have been allowed out to graze – the problem has not gone away. As our sheep wandered our pastures last summer, the heavy loads of parasites within them dropped millions of eggs onto our fields via the manure that our sheep produced. Those eggs were not easily killed over the winter, so they have laid dormant for months, waiting for seasonal warmth to hatch them out and produce the infective larvae that await our sheep this spring. Oh, some of the eggs and larvae that were present last fall were killed by the cold these past months, but I expect that 2017 will be among the worst we have seen – and that says something coming from a shepherdess whose sheep came in from the fields last fall carrying fecal egg counts between 20,000-30,000 eggs per gram of manure!

So, I’ve been trying to come up with a plan for our sheep. The basic parameters are these: parasite larvae are much more dangerous to lambs than to yearlings, and more dangerous to yearlings than to adult sheep, since adults tend to develop some level of resistance or resilience to the presence of parasites in their grazing fields. The yearlings have begun to develop this resistance, so they are better off than the lambs, who are wide open to infestation. High parasite levels can produce poor gains or weight loss, scouring (diarrhea), anemia, and eventually death. Using dewormers regularly can dramatically reduce the internal parasites present, but this regular use creates parasites that are resistant to the dewormers used, creating an even more difficult long-term issue. We are starting the year off with sheep who are strong and healthy, having been essentially cleared of these parasites over this past winter – but not for long, if they go out onto our fields.

There are a variety of ways to clear a field of these infective parasites. If one makes hay off of a field, it is essentially “clean” of parasites. Once the vegetation regrows, it can be grazed without issues for a time – until reinfected by the species that grazes it. Also, since parasites are fairly species specific, grazing another species on a particular piece of land can help clean things up, too – so if our sheep grazed cattle pasture and allowed the cattle to come here to our fields, our land would no longer harbor so many sheep parasites – and my neighbor’s cattle land would have less cattle parasites. I’ve also been toying with burning the forage cover of our fields, thinking that the fire would likely kill the eggs as well or better than a drought, which would also clean up a pasture. Finally, one can leave land dormant – without any sheep on it – for half a year, from January 1 to July 1 or from July 1 to January 1. Since the parasites hatch out of their eggs in warm weather and then travel up the grass blades daily in hopes of being ingested to complete their life cycle, the lack of grazing stock to eat them would eventually kill the larvae. They basically die of old age. The pasture isn’t totally clean, but it would be close enough – but that’s a lot of grazing time lost!

With so many choices, I’ve been debating our best move for this year. I initially hoped that we could burn our pastures, but because I don’t leave a lot of cover on our fields in fall because I want the cold to get all the way to the parasites, there isn’t enough to burn in spring. Great idea, but not workable here this year.

My next thought was to only graze our lambs and their mothers – essentially half of our flock – and leave the adult ewes and adult rams on hay until July 1. The advantage to this is that our lambs and their mothers – those sheep who need the nutrition the most – would be on pastures where the best nutrition is found. The lambs would learn how to graze from their mothers, so that when sold or maintained in our flock, we wouldn’t have to worry that they would end up eating poisonous plants because of lack of experience in grazing. With less pressure on our fields, we could leave half of the acreage unused until July 1, allowing the parasites there to die off. The disadvantage is that the most susceptible part of our flock – the lambs – would be the most at-risk for infection this spring. But they need to learn to graze.

This plan means that I would have to buy enough hay to get our rams and the ewes without lambs through the summer on hay. I originally thought that I might get a friend to make hay on those unused fields – and then feed that to our adults. Yet, that thought won’t work – for a really dumb reason. Our fields are accessed through twelve foot gates, and the hay cutter needs at least a fourteen foot access. Unable to get the equipment in, I am left to keeping those fields unused for the months necessary to clear them out. That means that I would be buying hay for half the flock over the summer – an expensive premise.

Yet, losing sheep is expensive, too. When I think back to the sheep I lost last year to these parasites last year, I could easily feed the adult group until July 1 on the money lost with those deaths! More about this topic on Wednesday, as I try to gel a plan for the next few months.

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  • Elaine Chicago says:

    Wow!! There’s really not a good choice, is there? Can you switch out the cows for the sheep?

  • Jane M says:

    That looks like an interesting choice as well. Surely other animals are living with the “perfect storm” parasites?

    Did the cold kill any parasites or is that a really unanswerable question?

    • Dee says:

      Although there was likely some winter kill, my guess is that based on the winter ee had, it won’t be enough considering the levels we had in the fall. I know others are dealing with similar issues, but every situation is different based on the number of animals grazed per acre, the farm’s deworming regimen, how much the shepherd knows or understands about parasite resistance, etc. I like to plan ahead and be prepared – obviously! 😊

  • Erika says:

    Can you get a steer to graze the summer, then sell at least some of the meat (using the steer as a haying machine) to offset the cost of some of the hay you will have to buy?

    • Dee says:

      Yes, but… When we first bought our acreage, it was being grazed by cattle, with countless cattle manure “plops” everywhere. It took many years before the flies died or went elsewhere! Our kids used to play fly killing games like using a fly swatter and comparing who could kill more fliws with one smack – and they would easily get 30 flies ir more at one time. Honestly, I’m not sure Im ready to go back to the swarms on the house siding and windows, but it would help offset the cost of hay. Right now, nothing is off the table…

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