The trade-off

Our first frost date typically arrives in early October, and by this point in November, it’s usual for grazing to have shut down and for hay to be the major part of the flock’s diet. This year, however, our ewes were still on pasture until last Friday’s big snowstorm. But because there wasn’t a lot left, I’d opened all of the pasture gates, giving them full access to whatever was out there. The fact that they could still find enough nutrition on our pastures was a boon to our budget, allowing me to hold on to our hay in case the growing season starts late next spring — and if it doesn’t, we can carry over any extra hay to next fall. Extra hay is a great thing; it saves us money (per bale) and time (in buying and stacking).

Yet there is a trade-off in having this extra hay. Good grazing this late in the year means that we’ve had good weather for grass growth: mild temperatures to keep the grass alive and enough rain to sustain continued growth. However, such weather is also ideal for the life cycle of internal parasites that might be in our fields. As I tell all new shepherds, when you raise sheep, you also raise grass/forage and the parasites that eventually invade the sheep. The ultimate goal is to breed for strong, healthy sheep; good, prolific grass; and sickly, weak parasites.

We have found through the years that parasites don’t usually seem to be much of an issue for the adults of our flock. Over time, we have selected for flock members who seem to be able to handle the parasites of our fields. The experts tell us that this type of selection — the culling of sheep who need frequent deworming — results in flock members who are either resilient or resistant. The sheep can either carry a heavy parasite load without any obvious health impact (resilient), or they become resistant to the parasites, eliminating them from their systems without human interference via chemical deworming. I don’t care whether they have the load or not, as long as they are healthy!

Because this year’s weather conditions have been so good for late grazing, a couple of things have happened: the sheep have been exposed to more parasites in the fields, and the sheep have been exposed to those very many parasites for much longer. Whereas they would normally be done grazing and onto parasite-free hay in mid October, here they were last week in mid November, still being assaulted almost daily as they ate grass from our fields. This has been a tough year for sheep — at least in this region — when it comes to internal parasites!

This has been reflected in both our adult sheep and our lambs. First, we’ve noticed that some of our adults who haven’t been dewormed in five to seven years have needed a dose of dewormer in the past few months. I have no problem giving them a bit of dewormer this year, recognizing what they have been up against. After all, one dose of dewormer every half-dozen years is not a lot, particularly considering that many flocks are hit with a chemical dewormer every six weeks or so, like clockwork! If our sheep need it, they can certainly have a dose here or there during a year like this one.

Deworming with chemical dewormers is something that must be carefully considered. The problem is that there are only three different families of dewormers and, like antibiotics, they must be used carefully to avoid the development of resistance. The more one uses a dewormer on the flock, the less that particular dewormer will work when it is really needed. This is the reason why we no longer routinely deworm the entire flock. We deworm only those sheep who are symptomatic, and we keep close track of which sheep have gotten a dose. In that way, we discern those individuals that need frequent deworming.

The other thing we’ve noticed with these weather conditions is that even our lamb flock was having some issues with parasite symptoms. We don’t usually see this in most years, and it requires immediate deworming. Our usual practice is to deworm the entire lamb flock when they are weaned and then again when they come in for hay in the fall. Doing this allows the youngsters to maximize the nutrition they get over the winter, strengthening them to fight against parasites they may come across again in the spring. Healthy, strong sheep are much more efficient at fighting off internal parasites — again, either because of resilience or resistance.

The only other group we routinely deworm are the yearling ewes (nearly two years old when they give birth), who get a dose of dewormer in the lambing jugs after delivery. This helps them go into the upcoming grazing season with a greatly reduced internal parasite load. By deworming these two groups (lambs in fall and nearly two-year-olds in the jugs), we’ve found that we can keep the worst of the parasite attacks at bay with minimal intervention.

Grazing late in the season has been a boon to our bottom line, but it doesn’t come free. The benefits of good grazing tend to be countered with an overabundance of internal parasites in the flock. Although I am thankful for the reduced hay costs, I’m happy now that our flock has moved out of the fields and we can get their internal parasites under control. It’s too easy to lose sheep to the effects of those nasty parasites if the shepherd is not vigilant!

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