Goats for Companion Grazing, Weed & Brush Control

At Giant Stride Farm, we use our cashmere goats to control Canadian thistles, willows, poplar shoots, wild roses, dandelions and stinging nettles. It has been our experience that willow and poplar shoots are their favorites - especially willow. When turned out on a new pasture with two foot high alphalfa, timothy & brome, their first priority was to devour the resurgence of willows. They are successfully controlling Canadian thistle in one pasture which was virtually overgrown with the weed.

A number of studies have been done using goats to control knapweed & leafy spurge. They also consurme wild iris. Live growing alphalfa and clover are two of their last food choices. These characteristics make them an excellent choice for companion grazing schemes with cattle and horses.

Bret E. Olson from the Dept. of Animal & Range Sciences, Montana State University stated that goats, when compared with cattle, have a relatively larger mouth opening for the size of their heads. This enables them to strip twigs, leaves, or flower heads from the fibrous stems often found in weeds. The mobile part of their tongues is longer than it is in cattle providing greater dexterity for removing certain plant parts. Their total salivary gland weight is higher - a possible counter adaptation to overcome the chemical defences of some plants.

One study conducted on the effect of goats on leafy spurge indicated that stem densities decreased by 85% in a four year period. Shrub densities decreased by 92% whereas herbage production from grasses increased 17% due to the removal of the leafy spurge canopy.

Another study indicated that when cattle were grazed alone, stem densities of leafy spurge increased slightly after two years. They decreased by 32% when goats were grazed alone. They decreased by a whopping 73% when the goats and cattle were grazed together. Sionce the cows consumed more of the grass cover, the goats in turn ate less of the grass and more leafy spurge. This supports the benefits of companion grazing.

When the grazing habits of goats and sheep were compared, it was found that goats took 64% of their bites from leafy spurge whereas sheep took only 20% of their bites from this noxious weed. Scientists generally agree that weed control depends on the repeated defoliation of plants during the growing season rather than a single defoliation. Since goats actrually prefer weeds over grasses, they will repeatedly seek them out. This makes them the best choice of domestic livestock for controlling weeds.

Mature grasses generally contain greater amounts of cellulose than browse or forbes. This cellulose must be stored while awaiting digestion by the ruemen flora. Since cattle are larger animals, having larger rumens - they are better adapted to the consumption of mature grasses. On the other hand, goats tend to select browse as their primary food choice - browse contains higher amounts of lignan - an almost completely indigestible portion of the cell wall that actually interferes with the digestion of cellulose. The indigestible lignan passes quickly through a goats system due to the relatively small rumen and high digestive turnover rate. The goats can then benefit from the available cellulose without wasting a lot of energy in the digestion process.

The presence of compounds like alkaloids, tannins & terpines in plants also influences an animals food choices. Cattle have been known to abort after consuming pine boughs which are high in terpines. They may also react to poisons such as digitalis, present in larkspur or poisonweed. Goats, for the most part, thrive on pine boughs and appear to be unaffected by larkspur. Other poisonous plants such as locoweed, lupins, choke cherry and water hemlock aren't likely to harm goats provided other sources of forage are also available. Goats tend to select a bite here and there from a variety of plants. This tendency is likely what prevents them from comsuming dangerous levels of toxic weeds.