Beneficial characteristics

Goat browsingSeveral characteristics of goats make them the animal of choice for vegetation management. Goats are a low-input animal, require a minimum investment for start-up, have low expenditures for maintenance, and require only a moderate level of labor for animal management. However, goats do require a high level of management knowledge. Goats have a diverse dietary preference and consume a wide variety of plants. They have very nimble lips allowing for selection and consumption of the most nutritious components of the available biomass. Goats have a preference for browse and can consume significant amounts of forbs. They can stand on their hind legs reaching over 6 feet into browse plants. Goats tolerate higher levels of tannins than cattle or sheep and rarely bloat. In addition, they have few problems from plant toxicity as the large number of plant species consumed daily generally prevents consumption of a toxic dose of any particular one. The diet diversity of goats probably minimizes their likelihood of mineral deficiencies.

Through their grazing habits, goats reduce the production of seeds by consuming seeding stems; the immature seeds consumed do not survive passage through the digestive tract. Goats may reduce woody vegetation through debarking, resulting in plant death. Through digestion and the passing of feces and urine, goats release plant nutrients tied up in unwanted vegetation making those nutrients available for other plant growth. Further, as goats make progress in controlling vegetation, ticks and snakes can be reduced due to reductions in their habitat. A final benefit of using goats to control vegetation is that while these animals consume undesirable plants they are producing a saleable product. Instead of spending between $10.00 and $25.00 per acre for chemical control, goats may provide a return of $10.00 to $25.00 per acre while controlling vegetation.

Dietary preferences

It is necessary for goats to consume a plant in order to control it. Therefore, the question is, “Will goats eat the target species?” This is not a simple question to answer because many factors affect what plant species a goat will consume. The greatest factor in determining what plant species a goat consumes is what they learned to eat from their mothers. Goats can also learn from their peers, although to a much lesser extent. The second biggest factor relates to year of birth in that animals born in a year in which there was a greater availability of a particular weed species, usually due to climatic conditions, will have learned to eat more of that species. These two factors account for different groups of goats having different dietary preferences.

Dietary preferences also change with time of year and location. In central Oklahoma goats eat significant amounts of red cedar only during the winter, but in Kansas and Missouri goats will consume red cedar in the summer. In many cases, goats will walk past a certain plant species for weeks and then one day decide that it is time to eat that species. Also, at some locations goats will eat a given species, but the same goats at another location will not consume that species, presumably due to differences in soil/climate factors affecting plant palatability. Thus, it is difficult to predict whether goats will consume a specific weed at a specific location.

There are many plant species that are preferred by goats regardless of location. Highly preferred plant species include blackberry, green briar, sumac, winged sumac, winged elm, poison ivy, ironweed, sericea lespedeza, and kudzu. Moderately preferred plant species include post oak, blackjack oak, multiflora rose, sunflower, buckbrush, and some thistles. Most grasses fall into this moderately preferred category. Lesser preferred plant species include Osage orange, Illinois bundleflower, hackberry, ragweed, and giant ragweed.

Goats will not provide the rapid control or eradication of undesirable vegetation seen with herbicides. However, one should see evidence of the target plant species being consumed by the end of the grazing season. Often, highly preferred vegetation may be grazed “into the ground” by summer’s end. Do not fret if the target plant species has not been grazed by the middle of summer. It is likely that the goats will graze it later in the season. If goats are not consuming the target plant species, there are two possible remedies. The first is to find some goats that consume that plant species and add them to the herd to teach the current animals to consume it. The second is to train some animals to eat that plant species. One researcher has been somewhat successful in training animals to eat weedy species and her techniques are located at www.livestockforlandscapes.com. Trained animals also taught peers to eat the targeted plant. Further, goats will not penetrate tall vegetation readily and mowing strips through dense vegetation will help goats to penetrate it.

Vegetation control

Sumac sprouting from rootsTime is needed for goats to sustainably control brush and weeds. Brush and weeds are not as well adapted to repeated defoliation as are grasses and repeated defoliation stresses these plants and reduces carbohydrate reserves. This stress makes the plant more subject to damage or death through insect and disease attack. Finally, when the root carbohydrates are depleted, the plant will die. Stripping of bark by goats, such as seen in honey and black locust and red cedar, will kill woody trees. Some annual plants are controlled through the consumption of seed stems as mentioned previously. However, for most plants there is an accumulation of seeds in the soil (seed bank) that will sprout back for several years. If control continues, the number of sprouts will decrease yearly as the seeds lose their viability. Some plants that have “hard seed” such as vetch and lespedeza will remain in the ground and continue to sprout for more than 10 years. One study with sericea lespedeza showed that grazing by goats caused more seeds in the seed bank to sprout, depleting the seed bank faster.

As expected, goats are much more effective at controlling unwanted vegetation if they are utilized early in an infestation, providing quicker control. Usually, however, vegetation problems progress to the extreme before control is attempted. Woody species can be more readily controlled at heights of less than 10 feet than at heights of 20 feet or more. At the latter heights, control may require an extended period of time and/or pretreatment such as burning or chaining.

Some producers may choose to maintain brush as a renewable feed resource for their goats. To achieve this, don’t allow goats to defoliate brush during the first month of spring growth, do not allow goats to defoliate it severely at any time, and allow 8 weeks recovery between defoliations. To fully recover and develop carbohydrate reserves for future regrowth, do not defoliate the month prior to expected frost. Conversely, if the goal is to kill brush, it should be defoliated early in the spring, repeatedly defoliated throughout the growing season not allowing it to recover, and grazed late in the fall. This is typically what happens under continuous grazing management.

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