Pasture Management for Parasite Control

 

In the early spring, we literally sit and stare at the grass on our farm. Here on our Vermont hillside farm, we only graze 5-6 months out of the year. After months of eating hay, the sheep can not wait to get out on grass. With grazing comes the joys of pasture management for parasite control. On our farm, we conduct our own fecal egg counts to help monitor parasites in the flock. I begin testing fecal samples after they have been on grass for about 3 to 4 weeks. I first test sheep that seem to be showing symptoms of having an over load of parasites, and then will work through the entire flock, testing each one.

Symptoms of Parasite Infestation-

diarrhea, thin and poor condition, poor wool quality, low FAMACHA score (pale membranes indicating anemia), not gaining weight

 

Not every sheep showing one or more of these symptoms will have a high parasite egg count, as other things may cause the same symptoms. For instance, eating lush grass can cause diarrhea and may not necessarily be due to parasites. That is why it is so important to test those with symptoms rather than simply administering deworming medications to all of them. In order to prevent a resistance to the deworming medications, we only treat those that need treating. If a sheep scores low for parasite eggs, but is doing well otherwise, I will let that sheep’s immune system fight before I will treat them. I often find that the sheep on my farm that have the most difficulties are the ones whose immune systems are compromised either due to being young (lambs), lactating, or being in poor condition.

There are several pasture management techniques that we do to try to minimize the impact of parasites on our flock.

Pasture Managment for Parasite Control

• Rotational Grazing-Though the fields look so beautiful with the sheep dotted all across them, we subdivide our pastures into small sections that the sheep can graze fairly quickly. This way, the sheep move to a new section of pasture before the parasite larvae has had an opportunity to hatch.
• Avoid Over Grazing-We move the sheep to a new section of pasture when they have grazed to about a 3-5 inch height. This can become challenging in the late summer/early fall when the grass is not growing as quickly and forage is waning. Parasite larvae lives on the lower 1 1/2 inches of the grass blade. By moving the sheep before they graze too closely, you are preventing them from picking up additional parasite.
• Cycle Through-On our farm, we have to cycle through all of our pastures more than once within a season. The longer you can stay off of a field inbetween grazing, the better. We try to keep the sheep off for at least 5 weeks, but sometimes can hold them back 6 or 7 weeks.
• Hay then Graze-We have one farmer who has a hay field next to our fenceline. He allows us to graze lightly after he has gotten his hay cut. Usually, we graze his field in the early spring or the late fall. Haying a field will burn off any parasites and provide a clean pasture for grazing.
• Companion Graze-Cows and sheep or horses and sheep, make great companions in a pasture as they do not share the same parasites. Unfortunately, we do not have cows or horses on our farm so this is not an option for us, but I wanted to include it in my lists for those so blessed to be able to companion graze.
• Provide Forage High in Tannin-Studies show that forage high in tannin can help reduce parasite loads in ruminants. This year, we have planted a new field with a mix of pasture grasses, chicory, and birds foot trefoil. Next year, we will be able to graze this area in hopes of helping sheep who need an extra boost. We also allow our sheep to do some browsing at the edges of their fields, eating leaves which will provide higher levels of tannin.

  

Needless to say, I have spent the better part of the past couple of weeks setting up fencing and moving sheep. Once the fencing is set up, it can usually stay in place all summer as we rotate our sheep through the fields.

Shepherd’s Note:
The messy bum in the photograph at the top of the page belongs to our ram Evret. When I saw his dirty bum yesterday morning, I thought for sure he had a high parasite load. I tested his fecal sample and there was not a single parasite egg visible. His diarrhea is due to being recently introduced to lush pasture. I will check him again in a couple of weeks just to be sure.

The following posts may be of interest to those wanting to read more about parasites and fecal egg counts.

Managing Summer Parasites
Boosting Your Pasture Nutrition Through Frost Seeding