Goat Nutrition

Appropriate nutrition is essential for the health and productivity of all animals and is the foundation of any successful production system, therefore, a focus on goat nutrition will help establish a profitable enterprise regardless of whether it is focused on meat, fibre, or milk production. Meeting all nutrient requirements (water, carbohydrates, protein, fat, minerals, and vitamins) for the class of animal (growing, pregnant, lactating etc.) is essential for profitable goat production.

Like cattle and sheep, goats are cud-chewing, even-toed ungulate (hooved) ruminants, that possess a unique four-chambered stomach (reticulum, rumen, omasum, and abomasum), which supports fermentation before digesta reaches the small and large intestines. Although nutrient requirements differ in several ways, many of the principles for feeding sheep is still applicable to goats. However, the dietary preferences and grazing habits of goats differ from sheep as goats are predominantly browsing animals.

Goats like all ruminants have a symbiotic relationship with a diverse microbial population consisting of bacteria, methanogenic archaea, and eukaryotes (protozoa and fungi) residing in their gastrointestinal tract which undertake three crucial functions for the nutritional wellbeing of the animal (Qi, 2010), (NRC, 2007), (NRC, 2016), which are:

The primary means by which goats obtain nutrients from the feed they consume is from the end products of fermentation, with the most important being the production of volatile fatty acids (VFAs). The type of diet, whether it is high forage or high concentrate, is a major determiner of the type of microbes that reside in the gut and therefore which types of VFAs are produced. A diet that is grain-based and high in starch will produce an environment that is lower in pH which favours the more acid-tolerant starch digesting organisms resulting in an increase of propionate fermentation pathways. In contrast, a high forage diet produces a relatively high ruminal pH which favours fibre digesting microbes that result in a high proportion of acetate production (NRC, 2007), (Moran, 2022).

Water

Despite goats being among the most efficient domestic animals in their use of water, all animals should have unlimited access to fresh, clean, freely accessible water. Lactation, environmental temperature, the water content of forage consumed, amount of exercise, stage of production (growth, maintenance, pregnancy, lactation etc), and the salt and mineral content of diet will all affect water intake.

TABLE 1: ADAPTED FROM MLA (2022) IDENTIFIES THE RECOMMENDED WATER CONSUMPTION RATES FOR GOATS

Energy

Feedstuffs contain variable amounts of energy (derived from the breakdown of simple and complex carbohydrates, protein, and fat) that fuel the biochemical processes that are necessary to sustain life. The main role of dietary carbohydrates is to supply the goat with energy, firstly to the rumen microbes and secondly to the host animal.

Carbohydrates are the main source of dietary energy for goats, and these include a diverse group of compounds including monosaccharides (simple sugars such as aldopentoses and aldohexoses), oligosaccharides (containing 2-10 sugar units linked by glycosidic bonds) and polysaccharides (long chains of monosaccharides linked by glycosidic bonds). Polysaccharides such as cellulose, hemicellulose, starch, and pectin provide most of the goat’s energy (NRC, 2007).

The energy requirements of goats vary within animals and depend on many factors including sex, age, climate, physiological stage of production, body size, the amount of activity they undertake in a day and whether they are suffering any medical conditions (parasitism, dental disease, arthritis etc). If goats receive an energy-deficient diet it will cause weight loss, low productivity and ultimately death, and if energy is oversupplied this will usually result in excessive fatness that is also unhealthy.

Pugh (2022) suggests that the best way to assess whether energy intake is adequate is to regularly monitor the body condition of goats (the fat covering the loin, brisket, and ribs). A body condition score (BCS) of 1 is extremely thin and an animal with a score of 5 is extremely obese. In most cases, healthy goats will have a BCS between 2.5 to 4.

Another crucial role of carbohydrates is to help maintain a stable gastrointestinal tract (GIT) environment by the consumption of fibrous feedstuffs. The process of chewing fibrous material stimulates the production of saliva which contains natural buffering agents that help combat rising acidity levels in the rumen. Acidosis can result from diets that contain little fibre and excessive amounts of starch.

Protein

Proteins are comprised of amino acids, which are classified into essential (must be provided in adequate amounts by the diet) and non-essential (can be manufactured within the animal’s body). Most of the goat’s normal body functions require protein, including maintenance, growth, reproduction, lactation, hair production, and immune function. If protein is deficient in the diet, vital stores in the blood, liver, and muscles are depleted, predisposing animals to a variety of serious and possibly fatal ailments. If dietary crude protein falls below 6%, feed intake and digestibility are reduced, therefore, for the maintenance of mature, healthy animals a diet that consists of a minimum of 7% crude protein is needed, with requirements for growth, gestation and lactation being higher. Pugh (2022) also suggests that feeding adequate to slightly greater amounts of protein than required appears to aid in the control (both resistance and resilience) of internal nematode parasites.

Goats have protein requirements at two levels, with one being the nitrogen (N) requirements of rumen microbes and the other being the requirements of the host animal. Rumen microbes can synthesise protein using nitrogen from plant ingredients (true protein) as well as having the ability to synthesise protein from non-protein nitrogen sources like urea. The microbes themselves are also a source of protein that the goat can utilise as they use ammonia to build their own bodies (synthesising microbial crude protein or MCP), and as McDonald (2011) explains, “microbial protein passes from the rumen and is digested in the small intestine, making a contribution to satisfy the amino acid requirements of the host animal.” Most goats can receive their protein requirements from MCP, however, young growing animals and females in late pregnancy or lactation have much greater protein requirements that cannot be met by MCP alone and these animals usually require undegradable dietary protein (UDP) which escapes or “bypasses’ the rumen fermentation where it is digested in the small intestine to supply amino acids directly to the animal.

Successful feeding of protein supplements can increase the digestion and performance of goats eating low protein and high fibre diets. Supplements that contain both NPN (non-protein nitrogen) such as urea and protein meals such as copra or cottonseed, are preferable as the urea provides a quick boost to rumen microbes, while the protein from the meal is slowly degraded in the rumen and additionally supplies the animal with bypass protein (see Table 2 for ingredients with high bypass protein %). This combination enhances the rate of digestion, stimulates appetite, and allows the animal to effectively graze and digest low quality forages for longer.

TABLE 2: ADAPTED FROM FUTURE BEEF (2022) IDENTIFIES THE NUTRIENT COMPOSITION OF FEEDS USED IN PROTEIN SUPPLEMENTS ON AN AS FED BASIS

Fats

Fats provide three basic functions in the goat body being:

If a doe must rely on fat reserves to meet energy requirements during gestation this can result in an excess production of ketone bodies, which can lead to a condition called ketosis. In goats, this is known as pregnancy toxaemia, occurring in late pregnancy, and is associated with multiple births or a large foetus and can result in abortion or the birth of weak kids.

Minerals

Minerals are required for an array of important functions in the animal body including (NRC, 2007), (McDonald, 2011), (Underwood, 1999):

Mineral nutrition should be a priority to goat producers because animal production, reproduction, immunity, and survival may be compromised when a mineral is outside the adequate range for individual animal requirements (see Table 3 for mineral requirements). Essential minerals are divided into macro minerals (required in gram quantities per day) and micro minerals or trace minerals (required in small quantities, parts per million or less). Mineral requirements vary between different classes of animals, with rapidly growing, pregnant, and lactating animals having greater mineral requirements compared to goats at maintenance or lower levels of production.

Plants and plant products form the main supply of minerals to goats, with plant mineral content being influenced by the stage of maturity of the plant, the type of soil (soil conditions and mineral content affect the uptake of minerals by plants and this can be further influenced by fertiliser application), climate, and seasonal conditions. Generally, legumes tend to be richer in mineral content, especially macro minerals, and this is the case with the seeds of legumes compared with the seeds of grasses and cereals (McDonald, 2011).

Providing goats with access to an ad-lib supplement that contains broad-spectrum minerals is useful in helping to avoid mineral deficiencies that can negatively impact production by resulting in ill-thrift, bone breakages, poor growth, and fertility.

TABLE 3: ADAPTED FROM MLA (2022) SHOWS THE DIETARY REQUIREMENTS OF GOATS FOR MACRO AND TRACE MINERALS

Thirteen other minerals are considered essential for certain types of animals under some conditions although there are no established daily requirements and these comprise boron, chromium, silicon, molybdenum, aluminium, arsenic, fluorine, lead, lithium, nickel rubidium, tin, and vanadium (Underwood, 1999), (NRC, 2007).

Vitamins

Vitamins are measured in international units (IU) and are organic compounds that are required in small amounts compared to other nutrients for normal growth and maintenance of animal life (McDonald, 2011). Vitamins are divided into two categories:

Vitamins A and E need to be provided in the diet and are readily available in high-quality forages. Vitamin D is synthesised in the body by exposure to sunlight, rumen microorganisms synthesise vitamin K, and the B vitamins and vitamin C is synthesised from L-gulonic acid within the cells of the goat’s body (Bender, 2003). Because neonatal (newborn) goats don’t have a functioning rumen they rely on dietary intake of vitamins to fulfil their requirements. The NRC (2007) indicates that ruminal flora may contribute significant amounts of B vitamins as early as 8 days with self-sufficiency occurring once the rumen becomes fully functional, however, (Cummins, 1991) suggests that vitamin C may not be synthesised in sufficient amounts until about 3 weeks of age.

Deficiencies in vitamins A and E have occurred under extreme drought conditions due to prolonged periods without green feed, therefore, you will often find these vitamins included in protein supplements designed for dry feed supplementation.

Supplementation

Production goals can be negatively impacted due to an inadequate supply of one or more nutrients, e.g. energy, protein and minerals, and supplementation should be focused on the primary limiting nutrients (the nutrients whose inadequate supply is limiting production). For example, goats that are grazing phosphorus-deficient country will have a better response to phosphorus supplementation when pasture quality and quantity is high (wet season) than they would in the dry season because when it is dry, protein and energy are the primary limiting nutrients.

In addition to essential nutrients, some supplements include metabolic modifiers like ionophores, which improve digestion through influences on the gut microbiota and are designed to improve feed efficiency, improve growth rates on high roughage diets due to increased digestibility of dry matter, increase production of propionate, increase utilisation of dietary nitrogen, as well as decrease acetate and methane production, decrease bloat, decrease acidosis, and aid in the control of coccidiosis (NRC, 2007), (McGuffey, 2001), (Tedeschi, 2003). Of the two main ionophores used in Australia, lasalocid is approved for use in sheep, while monensin is approved for use in goats.

Dry Feed Supplements

Protein supplements are designed to improve the intake of dry, fibrous fodder (by up to 25-30%) by providing rumen microbes with a source of ammonia that is efficiently used by rumen microbes allowing their populations to multiply, increasing the rate of digestion, and therefore increasing dry matter intake. Supplements that include both urea and protected protein meals are preferable as the urea provides a quick boost to microbes and the protected protein will be directly available over a longer period (refer to Figure 1). This combination enhances the rate of digestion, stimulates appetite, and allows the animal to effectively graze and digest poor quality fodder for longer.

MegaMin Graze & Grow 3% Urea is a balanced protein supplement with 3% urea, protected protein meals, broad spectrum macro and trace minerals, vitamins and RumensinÒ.

Key Attributes:

MegaMin Dry Feed Block is a urea and protein meal block with macro and trace minerals.

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Green Feed and Production Supplements

Goats should be carefully transitioned onto lush green fodder and should never be introduced for the first time when hungry. Prior to introducing to lush green feed, ensure that goats have been provided with fibre in the form of hay, straw, whole cottonseed, or any available roughage. Fresh, green grass is significantly high in sugars and has the potential to cause an ‘acidosis’-type situation that results in a decrease in rumen pH, like what can occur when ruminants consume grain without adequate fibre.

After goats have been safely transitioned onto sufficient green forage, protein and energy will no longer be the most limiting nutrients and supplementation should focus on rectifying any mineral deficiencies. With country that is deficient in phosphorus (P), it is best treated by concentrating on supplementing with P during green feed times. If goats are going to be grazing forage sorghum, or ticks and fly are a constant issue, then supplementing with extra sulphur (S) may be of benefit. Magnesium (M) is also a key mineral for areas where goats are run on improved pastures, ryegrass, and other cereals to help avoid the development of grass tetany.

MegaMin Phosphorus Supplements are formulated to promote production with extra phosphorus, calcium and broad spectrum minerals.

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MegaMin Sulphur Supplements contain high sulphur with phosphorus, magnesium, and trace minerals.

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MegaMin Magnesium Supplements contain high magnesium for livestock grazing lush geen feed.

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Pre-Kidding and Lactation

The nutrient requirements of does for energy, protein and minerals are highly elevated during the final 6 weeks of pregnancy because approximately 70% of foetal growth occurs at this time, in addition to the doe needing to prepare for lactation. The NRC (2007) identify some consequences of undernutrition during late gestation as being metabolic issues like pregnancy toxaemia, reduced milk production, and low birth weights resulting in poor kid survival.

Doe nutritional requirements are at their highest during the first month of lactation, especially if the doe is nursing multiple offspring. According to the NRC (2007) high-producing does have trouble consuming enough feed to supply the required nutrients during this period, and several nutrition-related crises may occur, such as ketosis, and hypocalcaemia. Providing early attention to doe nutritional requirements and avoiding sudden changes in diet and movement (stress) helps prevent the common nutritional maladies associated with lactation.

Grains, lupins, whole cottonseed, cottonseed meal or a balanced concentrate feed can help meet protein and energy requirements during late gestation and lactation. These ingredients can be mixed with a quality mineral supplement such as MegaMin Pre/Post Kidding to help meet the elevated mineral requirements at this stage of production.

MegaMin Pre/Post Kidding is a macro and trace mineral supplement to support health, fertility, and productivity.

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MegaMIn Pre/Post Kidding + Rumensin is a medicated mineral supplement to help support health, fertility, and productivity.

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The AgSolutions’ nutrition team are available to assist producers with goat supplementation enquiries in addition to offering feed testing and a ration formulation service for clients who wish to feed grain to ensure the supply of nutrients is sufficient relative to animal performance criteria. For more information, please contact us on 1800 81 57 57.

By Shannon Godwin (BAppSc GDTL)