Goats are considered small ruminants, a category that also includes sheep, South American camelids, and many cervids. Although goats and sheep are similar in many ways, they have substantially different nutritional requirements (see Nutrition: Sheep). Goats are intermediate browsers, meaning that they will select browse, forbs, and other readily digestible plant materials and also eat grass, whereas sheep tend to be purely grazers. Goats are adaptable to grazing on grasses but are more sensitive than sheep to plant fiber intake. Goats can consume up to 6.5% of their body weight as dry matter, resulting in a faster rate of passage through their digestive system. This fast passage limits their ability to digest lower-quality forage. Goats are more tolerant of copper intake than are sheep and may be predisposed to copper deficiency if fed mineral products formulated for sheep.
Metabolically, dairy goats are on par with high-producing dairy cows and require high-energy diets that may predispose them to ruminal acidosis. Inadequate intake results in loss of body weight and condition, which can lead to metabolic disease and impaired reproduction. Dairy goats can maintain an extended lactation of > 3 years with good milk production, in contrast to dairy cattle. As a litter-bearing species, goats require high nutrient intake to support late pregnancy; inadequate intake or dietary content can result in pregnancy toxemia.
Nutritional assessment in goats should be by routine body condition scoring, particularly as it applies to energy intake.
See also Preventative Health Care and Husbandry of Goats: Nutrition of Goats.
Water Requirements of Goats
Goats need unlimited access to fresh, clean, drinking water. Although they are among the most efficient domestic animals in their use of water, goats can die from a loss of body water of just 10%. Goats appear to be less subject to high-temperature stress than other domestic livestock species but should be kept in environments that provide shade. In addition to requiring less body-water evaporation to maintain comfort in hot climates, goats can conserve body water by decreasing losses through urine and feces.
Factors affecting water intake in goats include environmental temperature, water content of forage consumed, amount of exercise, stage of production (growth, maintenance, lactation, or pregnancy), and dietary salt and mineral intake. Goats grazing on lush pastures may require much less drinking water than those feeding on dry hay. Still, it is imperative to give all goats free access to water, regardless of their age, breed, purpose, life stage, or environment.
Daily water requirement is related to either body weight or dry matter intake. For goats at the maintenance stage, daily water intake should be 2–3 times dry matter intake—in general, 1.5–3.3 L of water per day (0.4–0.9 gallons per day). Lactation greatly increases the requirement to 4–5 times dry matter intake. Water requirements to support growth and pregnancy fall between the requirements for maintenance and those for lactation.
Water quality is also important. Dissolved minerals, which can alter water palatability, can be measured as either total dissolved solids (TDS) or "hardness" (calcium and magnesium content). A TDS concentration < 1,000 mg/L (< 1,000 ppm) is considered safe for all livestock, and concentrations of 1,000–5,000 mg/L are considered satisfactory. Water with a TDS concentration of 5,000–7,000 mg/L is only suitable for pregnant or lactating animals, and water with a TDS concentration > 10,000 mg/L should be avoided.
Of special concern for goats is soluble sulfate content, because rumen microbes can alter sulfates to form sulfides that bind to copper and other minerals, making them unavailable for use by the body. Total soluble sulfates in drinking water should be < 500 mg/L (500 ppm).
Energy Requirements of Goats
After water, energy is the most important dietary requirement for goats. Dietary energy can be measured in terms of digestible energy (DE), metabolizable energy (ME), or total digestible nutrients (TDN). ME is the preferred metric in goats, because it accounts for fermentation losses in the rumen. TDN requirements lie between DE and ME requirements, and TDN is the most commonly used metric, because it is provided on most feed analysis reports.
Insufficient energy provision is a common problem in highly productive goats (ie, those in the pregnancy, growth, and lactation stages of production) and may result from inadequate feed availability or poor diet quality. In contrast, goats in the maintenance stage and pet goats may be prone to excess energy intake, leading to obesity. Energy requirements are affected by body weight, body condition, sex, breed type (dairy vs meat), stage of production (growth, maintenance, pregnancy, and lactation), and environmental conditions. Ambient temperature, humidity, and wind velocity may increase energy requirements. Shearing mohair from Angora goats and pashmina from Cashmere goats decreases insulation and results in increased energy needs (at least in colder environments).
Grazing activity in goats ranges from light in goats under intensive management, to moderate in goats grazing on semiarid land, to heavy in goats on sparsely vegetated grassland or mountainous pastures that necessitate long-distance travel daily. Increased activity raises the maintenance energy requirement. Concurrent medical conditions (eg, parasitism, dental disease, arthritis) can increase energy needs, although these are not accounted for in requirement models.
The best indicator of adequate energy intake in goats is proper body condition (ie, fat cover, particularly over the loin, sternum, inner thigh, and ribs). A standardized body condition score ranges from 1 (extremely thin) to 5 (extremely obese). The optimal range for goats is 2.5–3.0. Scores may be slightly lower for lactating goats; slightly higher scores are desirable for successful breeding and during early pregnancy. Scores < 2.0 and > 3.5 are undesirable and may reflect nutritional issues and disease risk. If goats are parasite- and disease-free, yet underconditioned, they are likely being fed an energy-deficient diet; the reverse is true for obese animals. Goats should be monitored regularly for body fat changes using the standard scoring system, and scores should be entered in herd and individual medical record systems to facilitate objective decision-making regarding long-term dietary energy adequacy.
Goats are more metabolically active than sheep and thus have a higher maintenance energy requirement per unit of metabolic body weight (BWkg0.75). Dairy breeds have a higher maintenance requirement compared to nondairy breeds. The amount of energy needed to support growth depends on rate of growth and composition of weight gain. Early weight gain is more energetically efficient, because it is mostly protein and associated water, whereas gain in older, weaned animals is mostly due to fat deposition, which requires greater energy per unit of accreted tissue. Energy requirements during pregnancy are a function of total birth weight of fetal kids and day of gestation. Lactational energy requirements are a function of milk production and composition (ie, protein and energy content).
The National Research Council's report Nutrient Requirements of Small Ruminants (2007) provides tabular energy requirements for goats at all production stages. Diets containing 1.91, 2.39, and 2.87 kcal ME/kg (0.87, 1.1, and 1.3 kcal ME per pound) meet the energy requirements for maintenance, moderate productivity, and high productivity, respectively.
Protein Requirements of Goats
Dietary protein provides the amino acids required for most body functions, including maintenance, growth, reproduction, lactation, hair production, and immune function. Protein nutrition in goats is complicated: a proper diet must both provide dietary nitrogen sources for rumen microbial populations and then meet any additional amino acid needs with dietary protein sources not degraded in the rumen (ie, bypass protein). The objective is to optimize rumen microbial growth through a dietary balance of fermentable carbohydrates and rumen degradable protein (RDP). Rumen microbes not only digest these carbohydrates (hay and grass) into usable proteins for the goat but also serve as an important source of protein themselves for the animal. Rumen microbes are approximately 50–60% crude protein that is of high quality in meeting goats' amino acid needs. A diet low in RDP also decreases plant fiber fermentation and dry matter intake because of its effect on the rumen microbial population.
"Crude protein" (defined as feed nitrogen content × 6.25) is the term used to describe dietary protein content; however, it does not adequately reflect the difference between RDP and bypass protein. In goats, because of their faster rate of digestion, more protein bypasses rumen degradation than in sheep and cattle consuming the same feeds. Metabolizable protein (MP) is the sum of microbial protein and dietary bypass protein available for digestion and absorption in the intestine. However, MP is not directly measurable; it is predicted, using sophisticated dynamic rumen models. To ensure adequate RDP to meet microbial needs, a minimum degradable protein requirement as provided by 5–7% of dry matter intake (50–70 g/kg dry matter) is generally recommended.
Protein cannot be stored in the body. If goats do not receive sufficient protein through diet, their bodies begin to catabolize proteins in blood, liver, and muscle in an effort to mobilize available amino acids for critical metabolic functions. Severe and long-term body protein degradation predisposes goats to serious and even fatal disease consequences. Protein deficiency can compromise immune function, as well as the integrity of the intestinal barrier, leading to enteric bacterial translocation and sepsis. Feeding does additional protein, but not energy, late in gestation can increase their immune response and lower parasite fecal egg counts that normally increase around the time of kidding (eg, periparturient rise).
The minimum dietary crude protein requirement for goats is 7% (70 g/kg) of dry matter intake. Requirements are increased to support growth, gestation, and lactation. In kids, more protein is needed to support greater protein tissue accretion; their dietary crude protein requirements range from 16% (160 g/kg) dry matter for very young kids to 10% (100 g/kg) dry matter for weaned, growing kids. Protein requirements during pregnancy depend on the number of fetuses and only increase substantially in the last trimester; a minimum crude protein requirement of 12% (120 g/kg) dry matter is recommended, although concentrations of up to 16% (160 g/kg) dry matter may be needed in does with multiple fetuses. Highly productive dairy does may have a crude protein requirement of up to 20% (200 g/kg) of dry matter intake during early lactation, and this can decline to 12% (120 g/kg) in later lactation.
Grass forages contain adequate amounts of dietary protein for maintenance; however, lactating, growing, sick, or debilitated goats may need diets fortified with legumes or protein supplements (eg, soybean meal, cottonseed meal, distillers or brewers grains, canola meal, corn gluten meal). Nutrient content of browse and forbs is not well-documented; available data suggest they have a good nutrient composition, similar to that of legume forages. Given the opportunity, goats are capable of selecting high-quality feed resources when browsing.
Mineral Requirements of Goats
Mineral requirements for body maintenance and productive functions in goats can be described with factorial models. Maintenance needs account for the largest proportion of each mineral’s daily requirement and are a function of body weight and dry matter intake. Minerals needed for growth are those deposited in developing tissue or bone. Minerals required during pregnancy are those lost to the developing conceptus (ie, uterus, placenta, and fetuses). Lactational mineral requirements are a function of the minerals lost in milk.
Detailed, factorial models have been described for mineral requirements in sheep but not in goats. Studies of mineral metabolism in goats have primarily addressed requirements for macrominerals, especially calcium and phosphorus. Requirement models for most microminerals have not been definitively established for goats at either maintenance or production levels. If no model has been developed, the recommended dietary mineral concentration provided by the National Research Council can be used.
Feeding goats to meet their mineral needs maximizes production, reproduction, and immune system function. Mineral nutrition in goats, as in other ruminants, is complicated by mineral-to-mineral interactions, as well as by the rumen environment's impact on dietary mineral bioavailability.
Macromineral Requirements of Goats
Macrominerals are dietary elements required in grams or ounces per day. They serve as components of skeletal structure, electrolytes involved in acid-base balance, and elements in membrane ion gradients, nerve conduction, muscle contraction, and high-energy bonds, among other functions. Key macrominerals for goat nutrition include the following:
calcium
phosphorus
magnesium
sodium
chloride
potassium
sulfur
Calcium requirements in Angora or meat goats are generally met under grazing conditions; however, in high-producing dairy goats, concentrations should be checked, because calcium deficiency can lead to decreased milk production. Goats in late pregnancy need more calcium to support fetal bone development and prevent gestational hypocalcemia. Some high-producing dairy does may also develop postparturient hypocalcemia if not fed adequate calcium. In browsing or grain-fed goats, adding a calcium supplement (eg, dicalcium phosphate, limestone) to feed or to a salt or trace mineral–salt mixture is usually sufficient. Forage legumes (eg, clover, alfalfa, kudzu, bird's-foot trefoil) are also good sources of calcium. The dietary calcium requirements for goats are 0.18% (1.8 g/kg) dry matter for maintenance and 0.65% (6.5 g/kg) dry matter for lactation.
Phosphorus is often the most limited mineral in grazing animals, as grasses are low in phosphorus. Soil fertilization can increase the phosphorus content of plants, and excess fertilization can cause phosphorus content to potentially exceed the requirements of animals. Soil pH is an important determinant of plants' calcium and phosphorus content, and neutral soils take up these minerals more efficiently. If acidic soils are not treated with limestone to neutralize soil pH, forages may become deficient in calcium and high in phosphorus, potentially leading to nutritional diseases in goats that consume them.
Phosphorus deficiency results in slowed growth, unthriftiness, and occasionally a depraved appetite (eg, pica). Goats can maintain milk production on phosphorus-deficient diets for several weeks by using phosphorus from body reserves; however, with prolonged phosphorus deficiency, milk production will decline dramatically. A dietary calcium:phosphorus ratio between 1.5:1 and 2:1 is recommended, because goats are predisposed to urinary calculi. Excess phosphorus intake, even with an appropriate calcium:phosphorus ratio, can predispose goats to urinary calculi formation due to excessive renal phosphorus excretion; therefore, monitoring of total dietary phosphorus is recommended. The dietary phosphorus requirements for goats are 0.14% (1.4 g/kg) dry matter for maintenance and 0.35% (3.5 g/kg) dry matter for lactation.
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Magnesium deficiency is associated with hypomagnesemic tetany (grass tetany); however, ordinarily this condition is less common in grazing goats than it is in cattle. High dietary potassium can impede ruminal absorption of magnesium. Goats have marginal ability to compensate for low magnesium by decreasing the amount of magnesium they excrete. Both urinary excretion and milk production are decreased with magnesium deficiency. The dietary magnesium requirement for goats is 0.12–0.22% (1.2–2.2 g/kg) dry matter.
Sodium, chloride, and potassium are critical electrolytes for acid-base balance, membrane electrical potentials, and osmotic pressure in the vasculature. Salt (NaCl) is usually recognized as a necessary dietary component but is often forgotten. Goats may consume more salt than needed when it is offered ad libitum; overconsumption does not present a nutritional problem but may depress feed and water intakes, especially in some arid areas, where salt content of drinking water is quite high. Salt is used as a carrier for trace minerals, because goats have a strong drive for sodium intake. (Contrary to popular misconception, goats do not have an appetite for individual minerals and are not capable of selectively consuming minerals to meet specific needs.) Adding salt to the diet can promote increased water consumption, which dilutes urine and decreases the potential for mineral saturation that can result in urinary calculi. The dietary sodium requirement for goats is 0.05–0.15% (0.5–1.5 g/kg) dry matter.
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Potassium plays an important role in metabolism. Forages are generally rich in potassium, so potassium deficiency in grazing goats is extremely rare. Marginal potassium intake occurs only in heavily lactating does that are fed diets consisting mainly of cereal grains. The dietary potassium requirement for goats is 0.5–1.2% (5–12 g/kg) dry matter. Higher dietary potassium intake may be beneficial in lactating dairy goats.
Sulfur is not directly required by goats but is provided in the diet as a sulfur source for rumen microbes to synthesize sulfur amino acids. A dietary nitrogen:sulfur ratio between 10:1 and 12:1 is recommended. Excess dietary sulfur can impede copper bioavailability, leading to copper deficiency. The dietary sulfur requirement for goats is 0.12–0.25% (1.2–2.5 g/kg) dry matter.
Micromineral Requirements of Goats
Microminerals, also known as trace minerals, are dietary metals required in nanogram or microgram amounts to meet nutritional requirements. These essential elements play important biological roles as antioxidants, immune regulators, and enzyme activators, and they perform many mineral-specific functions. Key microminerals for goat nutrition include the following:
cobalt
copper
iodine
iron
manganese
selenium
zinc
Micromineral requirements are not as well-defined for goats as they are for sheep. Instead of being predicted using a factorial model, most microminerals have a dietary concentration requirement.
Cobalt is required in the diet only to provide this mineral to the rumen microbes so they can synthesize cyanocobalamin, or vitamin B12. Vitamin B12 is an essential enzyme for one-carbon transfer, especially for the pathway that generates glucose from the volatile fatty acid propionate, which is generated in the rumen. The recommended dietary concentration of cobalt for goats is 0.1 mg/kg of dry matter intake.
Copper performs many functions in the body, and copper deficiency can result in microcytic anemia, poor production, lighter or faded hair color, poor fiber quality, infertility, poor health, slowed growth, some forms of metabolic bone disease, diarrhea, and possibly a greater susceptibility to internal parasites. Goats are prone to copper deficiency because of the many dietary mineral interactions that decrease dietary copper bioavailability. Goats can also develop copper toxicosis but are more resistant than sheep to this condition. Excessive administration of copper oxide wire particle (COWP) boluses as part of a parasite control program in goats can result in copper toxicosis, as can excessive feeding of dietary copper.
Copper in forage is highly dependent on geographical region. In the US, copper content of forage is typically higher in states east of the Mississippi River than in western states. Iron, zinc, sulfur, and molybdenum can impede copper bioavailability and may be present in the diet or drinking water. The dietary copper requirement for goats is 15–25 mg/kg dry matter, which is much greater than that for sheep (5–8 mg/kg dry matter).
Iodine-deficient soil, and crops produced thereon, occurs in some areas of the US. Therefore, goats should receive iodine through salt in a stabilized form such as calcium iodate. Sodium or potassium iodide is readily leached from mineral mixes with exposure to moisture. Conditional iodine deficiency can develop with normal to marginal iodine intake in goats eating goitrogenic plants (eg, brassicas). Marked iodine deficiency in goats results in goiter, poor growth, poor reproductive ability, and small, weak kids at birth. At delivery, kids may have clinical goiter, even when the dam does not, as a result of limited iodine transfer to the fetus. Recommended dietary iodine content for goats is 0.5 mg/kg dry matter.
Iron deficiency is rare in mature, grazing goats but can occur in kids, due to their minimal iron stores at birth and because dam’s milk is low in iron. Iron deficiency can cause anemia in goats. Iron deficiency is more common in kids fed in complete confinement and in heavily parasitized goats. Prevention measures include giving goats access to pasture and providing a good-quality trace mineral salt containing iron. Both copper and iron deficiencies can present as anemia, as indicated by a low PCV and white coloration to the mucous membranes. If a goat with anemia is nonresponsive to iron supplementation, copper status should also be evaluated. The dietary iron requirement for kids is 95 mg/kg dry matter and for all other goats is 35 mg/kg dry matter.
Manganese deficiency and toxicosis are generally not a concern in goats, as manganese occurs in adequate amounts in grasses. However, plants in some areas of the Pacific Northwest in the US have inadequate manganese content, and ruminants in these areas can develop manganese deficiency if they do not receive supplementation. Manganese deficiency can also occur in goats in various other regions, possibly because of soil factors that limit manganese uptake in plants. Because manganese plays a role in cartilage development, deficiency can result in abnormal bone growth. The recommended dietary concentration of manganese for goats is 20–30 mg/kg dry matter.
Selenium is an important antioxidant and immune function regulator. Dietary selenium deficiency in goats is associated with nutritional myodegeneration, retained placentas and metritis, poor growth, weak or premature kids, and mastitis. Soil properties, such as pH, moisture level, and presence of aluminum, influence plant uptake of selenium from soil. Crops in many regions of the US (east and west coastal states) and other parts of the world are selenium deficient. In contrast, the Great Plains region of the US has alkaline soils that promote plant selenium uptake, resulting in acute to chronic selenium toxicosis in goats foraging on those plants. Excess parenteral supplementation of selenium to correct deficiency in goats can also induce acute selenium toxicosis.
Because of the risk for toxicosis, dietary selenium supplementation is regulated by the FDA. The recommended dietary selenium concentration is 0.2–0.3 mg/kg dry matter. A free-choice, salt-based mineral supplement is permitted to contain up to 90 mg of selenium per kilogram of supplement, assuming a total selenium intake of 0.7 mg per day.
Zinc is associated with the functioning of more than 200 enzymes and influences tissue growth, reproduction, immunity, and general metabolism. Zinc deficiency results in parakeratosis, stiffness of joints, small testicles, and decreased libido. Excessive dietary calcium (eg, as can occur with alfalfa diets) may increase the likelihood of zinc deficiency in goats. Copper can also interfere with dietary zinc absorption. Models predicting goat zinc requirements indicate a low maintenance requirement of 10–15 mg/kg dry matter and a high requirement to support lactation of 40–50 mg/kg dry matter.
Vitamin Requirements of Goats
Vitamins are organic compounds that serve primarily as metabolic cofactors or hormones for regulating many body functions. Vitamins are either water-soluble or fat-soluble.
Water-soluble vitamins include all the B-complex compounds. It is generally believed that, in goats, adequate amounts of B-complex compounds are generated by rumen microbes. However, if the rumen environment is altered, as in acidosis, parenteral supplementation is indicated. Oral supplementation is not beneficial, because these compounds are readily consumed by rumen microbes.
The fat-soluble vitamins are A, D, E, and K. Of these, only vitamins A, D, and E have established dietary requirements for goats. Vitamin A plays important roles in vision, bone remodeling, epithelial differentiation, and immune function, and as an antioxidant. Vitamin D is essential for calcium homeostasis and bone development. Vitamin E functions as a membrane-bound antioxidant in concert with selenium. Requirements for these vitamins in goats are based on body weight, and needs increase during lactation.
Key Points
Goats have unique dietary requirements relative to feeding patterns and nutrient needs that preclude the use of feed products designed for sheep.
Goats are intermediate browsers, preferring to consume high-quality plant leaves, buds, and shoots, and they can reasonably meet their nutrition needs if allowed to browse.
High energy and protein requirements in late gestation and early lactation predispose goats to nutritional disease if their diets are improperly balanced or consist of poor-quality forage.
Compared to sheep and cattle, goats are less able to consume and digest low-quality forages, putting them at greater risk for body condition loss and increased disease susceptibility.
Supplemental calcium in late pregnancy supports fetal bone growth and minimizes hypocalcemia risk.
Goats are prone to copper deficiency but may also experience copper toxicosis, particularly when exposed to copper oxide wire particle boluses.
For More Information
Extension Foundation: Goat body condition score.
Body condition scoring. In: Code of Practice for the Care and Handling of Goats. National Farm Animal Care Council [Canada]; 2022:appendix F.
National Research Council. Nutrient Requirements of Small Ruminants: Sheep, Goats, Cervids, and New World Camelids. National Academies Press; 2007.
Cannas A, Pulina G, eds. Dairy Goats Feeding and Nutrition. CABI Digital Library; 2007.
American Consortium for Small Ruminant Parasite Control: Copper oxide wire particles (COWP).
