Tips on grazing for invasive plant control

Some tips on grazing for invasive plant control

Using livestock for controlling invasive plants has a lot of appeal; the animals seem like a natural, green method; they're cute; and at times they can be a very inexpensive way to do some weed control. But there are also various difficulties and issues with using livestock that should be understood before you jump into a grazing program, I've discussed some below. 

Livestock have different eating preferences and needs; Cattle (photo of cattle courtesy of Jack Kelly Clark, UCANR) like grass, sheep like grass and forbs, goats like browse (foliage on stems of woody shrubs, young stems and bark, like photo), and horses like grass.

They eat differently; cattle pull up plants with their tongues, sheep and horses clip off plants close to the ground, and goats pull foliage off of stems with their tongues.

The owner of the livestock (called the grazier) usually has a different goal for the animals then you do. The grazier wants the animals to fatten up for the market. You want them to eat weeds. If the weeds are what the animals want to eat and they are nutritious, then your goals are compatible. It is more often the case that the weeds are not desirable and the animals will try to eat everything else instead.

The grazier wants the animals to wander freely over a large area. You probably want the animals to be confined to a smaller area to maximize weed control. This requires fencing, which is a cost to the grazier. It also means the animals are being forced to eat plants they may not want to eat (Kind of like being forced to stay at the table and finish all of your lima beans when you were a kid).

 The grazier wants to turn the animals out to graze when she/he arrives at your site. You want the animals to stay in a penned area for 2-4 days eating hay and voiding all of the weed seed from their last site. You also want the pen in case of rain, rather than allowing the animals to wander around in the mud and trample small plants.

Livestock do not often eradicate weeds; they just remove above ground stems and foliage. The San Diego Weed Management Area tried goats for control of perennial pepperweed (Lepidium latifolium) a few years ago. The grazier promised that the goats would eradicate the weed if they were allowed to graze it twice in the summer for two weeks each time. They rented the goats to the WMA for $300/acre. The goats removed about ½ of the stems and foliage and a year later it looked like it had never been grazed.

Graziers are used to driving hard bargains, so make sure you know what you want and are ready to insist on it.

Don't get me wrong, livestock can be very effective and useful in large-scale weed management if they are suitable consumers of the target weed(s) and they are managed properly. I collaborated with several UC scientists to study sheep grazing as a weed control practice in newly planted alfalfa in the low desert. The sheep were very successful, as good as the herbicide alternative. Citations for three of our papers are on this website page (near the bottom). This short blog only presents some of the issues, especially those I have personal experience with. After spending eight years studying sheep grazing, I like to say that I know far more about sheep than I ever wanted to.