Forage Needs and Grazing Management for Meat Goats in the Humid South East
Goats offer an opportunity to more effectively convert pasture nutrients to animal products such as milk, meat, and fiber which are currently marketable and in demand by a growing segment of the US population. In addition, goats selectively graze unwanted vegetation in pastures and forests, thus providing biological control which will reduce dependence on certain chemicals.
Goats consume only the most nutritious parts of a wide range of grasses, legumes, and browse plants. Browse plants include brambles, shrubs, trees, and vines with woody stems. The quality of feed on offer will depend on many things, but is usually most directly related to the age or stage of growth at the time of grazing. The nutrient composition for several common feed types is shown in Table One.
Goats are very active foragers, able to cover a wide area in search of scarce plant materials. Their small mouths and split upper lips enable them to pick small leaves, flowers, fruits, and other plant parts, thus choosing only the most nutritious available feed.
The ability to utilize browse species, which often have thorns and an upright growth habit with small leaves tucked among woody stems, is a unique characteristic of the goat compared to heavier, less agile ruminants. Goats have been observed to stand on their hind legs and stretch up to browse tree leaves or throw their bodies against saplings to bring the tops within reach.
The feeding strategy of goats appears to be to select grasses when the protein content and digestibility are high, but to switch to browse when the latter overall nutritive value may be higher. This ability is best utilized under conditions where there is a broad range in the digestibility of the available feeds, giving an advantage to an animal which is able to select highly digestible parts and reject materials which are low in quality.
Grazing goats have been observed to:
Because of their inquisitive nature and tolerance of “bitter” or high tannin material, goats may eat unpalatable weeds and wild shrubs that may be poisonous, such as cherry and milkweed. The absence of the severity of poisoning is related to the quantity of the material consumed, the portion and age of the plant eaten, the season of the year, the age and size of the animal, and other factors. In addition, several ornamental plants that are grown outdoors or indoors are highly toxic. For example, goats should not have access to, or be fed clippings from yew, azaleas, delphinium, lily-of-the-valley, and larkspur.
In a pasture situation, goats are “top down” grazers. This behavior results in uniform grazing and favors a first-grazer-last grazer system. This might consist of using a goat herd as the first group and cattle as the last group. This management is most appropriate with lactating does or growing kids. Goats naturally seek shelter when it is available. Goats seem less tolerant of wet cold conditions than seep and cattle because of a thinner subcutaneous fat layer. A wet goat can easily become sick. Therefore, it is advisable to provide artificial shelters, such as open sheds.
The goat is not able to digest the cell walls of plants as well as the cow because feed stays in their gastrointestinal tract for a shorter time period. A distinction as to what is meant by “poor quality roughage” is necessary in order to make decisions concerning which animal can best utilize a particular forage. Trees and shrubs, which represent poor quality roughage sources for cattle, because of their highly lignified stems and bitter taste, may be adequate in quality for goats. Goats will avoid eating the stems, but don't mind the taste and will benefit from the relatively high levels of protein and cell solubles in the leaves of these plants. On the other hand, straw, which is of poor quality due to high cell wall and low protein, can be used by cattle but will not provide maintenance needs for goats because goats utilize the cell wall even less than cattle.
Goats must consume a more concentrated diet than cattle because their digestive tract is smaller relative to their maintenance energy needs. When the density of high quality forage is low and the stocking rate is low, goats will still perform well because of their grazing behavior, even though their nutrient requirements exceed those of most domesticated ruminant species. Total digestible nutrients (TDN) and protein requirements are given in Table Two. Comparing the nutrient requirements to the chemical composition of feeds shown in Table One should give producers an idea of how to match needs to appropriate forages. For comparison, low quality forages have 40 to 55 percent TDN, good quality forages have from 55 to 70 percent TDN, and concentrates have from 70 to 90 percent TDN.
High quality forage and/or browse should be available to does during the last month of gestation and to lactating does, to developing/breeding bucks, and to weanlings and yearlings. Female kids needed for reproduction should be grazed with their mothers during as much of the milk feeding period as possible and not weaned early. When the quality of available forage and/or browse is limited or of low quality, a concentrate supplement may be considered to maintained desired body condition, depending on the cost benefit. Whole cottonseed makes an excellent supplement for goats when fed at no more than 0.5 lb/head/day. Dry does and non-breeding mature bucks will meet their nutritional requirements of low to medium quality forage (10 - 12 percent protein and 50 - 60 percent TDN).
Providing free choice a complete goat mineral or a 50:50 mix of trace mineralized salt and dicalcium phosphate is advisable under most situations. Selenium is marginal to deficient in all areas of North Carolina. Therefore, a trace mineral mix containing selenium should always be provided to the goat herd year round. It is sometimes advisable to provide a mineral mix that contains 20 - 25 percent magnesium oxide to reduce the risk of grass tetany when heavy milking goats are grazing lush small grain or grass/legume pastures early in lactation. Cooper requirements for goats have not been definitively established. Growing and adult goats are less susceptible to copper toxicity than sheep, however, but their tolerance level is not well known. Young nursing kids are generally more sensitive to copper toxicity than mature goats, and cattle milk replacers should not be feed to nursing kids. Mineral mixes and sweet feed should contain copper carbonate or copper sulfate because these forms of copper are better utilized by the goat than copper oxide.