Shrubs for Livestock Forage for Mixed Species Grazing
I’ve been flipping through this book online as I’ve been researching drought-tolerant plants suitable for creating a silvipasture system for goats and chickens. My plan is to design a management-intensive multicell pasture for dairy goats and a dual-purpose chicken flock that will increase soil fertility while providing excellent milk, meat, and egg production, support good animal health and happiness, and do so in a small space.
The rationale for this mixed-species management-intensive grazing plan is as follows: Goats and chickens are each vulnerable to different sets of parasites. Parasite load on pasture is a big problem for goats. Chickens, however, can consume goat parasites with impunity, and in fact actually benefit from being grazed on a pasture with mammal manure and the insects that feed on it, which in turn make good food for the chickens. For their part, the goats benefit from decreased parasite load and fewer flies. Both goats and chickens benefit from mixed pasture and browse although in different ways—goats prefer to eat shrub and tree leaves and bark, while chickens prefer the growing tips of new grass. But goats also eat some grass and forbs and chickens can benefit from the fruit and seeds of many shrubs. An ecosystem consisting of mixed grasses, forbs, and woody shrubs and trees tends to be more resilient and productive when impacted by animals than an ecosystem of grass alone. This is especially true when plants are selected with care for their mutually beneficial interactions. Animal grazing in such ecosystems benefits plants, animals, and soils most when animals are moved through the pasture, allowing enough time for the plants to rest and recover before they face grazing and browsing again. The benefits of management-intensive grazing are widely accepted and include more robust animal health as well as decreased carbon emissions and even carbon sequestration in soils. Factors to consider in developing a schedule for goat/chicken pasture rotation include grass and forb regrowth periods as well as fly larva and other parasite hatch cycles, factors that will vary depending on climate, plant selection, and season of the year. In some regions a combination of rotation and mixture of plant species may reduce the need for supplemental feed to virtually none.
Limiting factors to management intensive pasture systems include the expense of fencing and the variability of pasture regrowth, which creates the need for close supervision of livestock rotation by a skilled manager. While the former may be mitigated by the use of inexpensive portable electric fencing, there is no substitute for the latter. Limitations of mixing shrubs with grasses include possibly a greater expense to establish, the relative slow growth of some shrubs, and the potential to shade out desired grass and forbs. These limitations can be overcome by carefully selecting complementary shrubs and pasture species, using those that are affordable and suited to your site, and choosing shrubs that grow rapidly.
These are some shrub species I’ve been considering for our site and the benefits and challenges they offer:
Siberian peashrub is a nitrogen-fixing leguminous shrub or small tree that grows rapidly and produces a protein-rich goat browse, edible seed pods and edible seeds. The seeds and pods should be cooked for human consumption, but chickens seem to eat them eagerly as they grow. The shrubs are thorny but this does not usually deter goats. It is both drought tolerant and extremely cold hardy, so much so that it is invasive in Alaska, while it does not grow as vigorously in areas of North America south of Nebraska. It is generally a fast-growing shrub. In places where it has the potential to escape cultivation, treating it to heavy browsing may help control its spread. In addition it is a superior bee forage and nectary plant. Cowpea-soybean-lupine rhizobia may be used as an inoculant for nitrogen fixation.
Amorpha fruticosa or californica
Amorpha fruticosa is also an excellent nectary and insectary, with attractive purple flower spikes. It is likewise a legume, fixing nitrogen in the soil, and as there is a closely-related California native species it may have symbiotic bacteria already present in the soil of my intended site. Of the shrubs proposed here it seems to have the lowest livestock food value, but I will consider using it anyway because of its other desirable characteristics and to add diversity to the planting. In my experience, goats tend to develop cravings—they pursue some plants to the exclusion of others for a time, then suddenly move on to a new favorite. For this reason I prefer to develop a diversified hedge, and would like to include Amorpha fruticosa or californica.
Honey locust, another leguminous shrub, is reported to be an excellent forage species with high protein foliage and edible and tasty seed pods. It is also good for firewood and could be managed as coppice to produce both forage and fuel. It does prefer deep moist soils, however, so although it is also reported to be drought tolerant it may not do well on a dry slope. There are many selections from the naturally occurring thornless variety inermis, including some selected for prolific production of pods, and other selected for no pods at all. “Millwood” is supposed to be the best forage variety.
Black locust has better feed value than Honey locust, and is more tolerant of dry soils. Its wood is also excellent firewood. There is not a commonly available thornless variety, and its bark has some toxic compounds, but these are said not to trouble goats. It is also a fast-growing legume.
Mimosa is reported to have a better feed value than Black locust, although lower productivity and perhaps less palatability. While it is listed as invasive in the Southeast, it does not appear to be invasive in Northern California. It is also an excellent bee forage and like all the aforementioned shrubs has the potential to fix nitrogen in the soil if associated with its symbiotic bacteria. It is likely to do well in the California oak woodland type environment.
The mulberry genus is widely distributed, in part because it has been used to feed the nutritionally-demanding silkworm. The same nutritional characteristics that make it indispensable food for silkworms make it an excellent food for ruminants and monogastric livestock. In addition it is highly palatable and sought after in preference to other forage. For this reason it would be important to allow livestock access to only well-established mulberry plantations, as goats are likely to climb into the lower branches to access more of the tasty leaves. The tasty and nutritious fruit is of benefit to chickens and likely to be enjoyed by wild birds as well as humans and other animals using the site. The leaves could also be used to supplement rabbit food, reducing the cost of raising these small monogastric livestock. Mulberry is not a legume, and its yields are increased by nitrogen supplementation, so its plantation in a mixed hedge with nitrogen-fixing legumes mentioned previously will benefit both—the mulberry by added nitrogen released into the soil when the leguminous shrubs are cut and browsed, and the legumes by the relief of excessively-preferential browse pressure.
The next topic in this series will be the grass and forb species I’m considering. After that I’ll discuss how I’m contemplating putting them together into a working system.