3. GOAT NUTRITION AND METHANE EMISSION
3.1. NUTRIENT REQUIREMENT FOR GOAT
Meat goats require nutrients for body maintenance, growth, reproduction, pregnancy, and production of products such as meat, milk and hair. The groups of nutrients that are essential in goat nutrition are water, energy, protein, minerals and vitamins. Goats should be grouped according to their nutritional needs to more effectively match feed quality and supply to animal need. Weanlings goats, does during the last month of gestation, high lactating does and yearlings should be grouped and fed separately from dry does, bucks, etc. which have lower nutritional needs.
When pasture is available, animals having the highest nutritional requirements should have access to lush, leafy forage or high quality browse. In a barn feeding situation such as during the winter months, these same animals should be offered the highest quality hay available. Whether grazed or barn fed, goats should be supplemented with a concentrate feed when either the forage that they are grazing or the hay that they are fed do not contain the necessary nutrients to cover their nutritional requirements. Total digestible nutrients (TDN) and protein requirements are shown in Table 4.
Table 3. Daily Nutrient Requirements for Meat Producing Goats
Nutrient Weanling (30 lb)
Yearling (60 lb)
Pregnant (Early)
Pregnant (Late)
Lactating (Avg Milk)
Lactating (High Milk)
Dry matter, lb 2.0 3.0 4.5 4.5 4.5 5.0
TDN, % 68 65 55 60 60 65
Protein, % 14 12 10 11 11 14
Calcium, % 0.6 0.4 0.4 0.4 0.4 0.6
Phosphorus,
% 0.3 0.2 0.2 0.2 0.2 0.3
1 Nutrient Requirements of Goats in Temperate and Tropical Countries. 1981.
National Research Council.
2 Pinkerton, F. 1989. Feeding Programs for Angora Goats. Bulletin 605.
Langston University.
3 Expected weight gain > .44 lb/day.
3.1.1. Water
There are many factors affecting the water requirement of goats including level of dry matter intake, physical form of the diet, physiological state of the animal (gestation, lactation, finishing, etc.), temperature of the water, ambient temperature, frequency of drinking, activity of the animal and the time of day, water is the cheapest feed ingredient. However, production, growth and the general performance of the animal will be affected if insufficient water is available. Water needs vary with the stage of production, being highest for early lactating does, and during times when the weather is warm and forages are dry. In some instances, when consuming lush and leafy forages, or when grazing forages soaked with rain water or a heavy dew, goats can get all the water they need out of the feed. However, water is almost always needed by some members of the herd such as lactating does. Because it is difficult to predict water needs, goats should always have access to sufficient high quality water.
Clear, flowing water from a stream is preferable to stagnant water; the latter may contain excessive levels of blue-green algae, which may be toxic. Nitrate in drinking water should also be of concern because it is becoming the predominant water problem for livestock. Safe levels in drinking water are as follows (in parts per million): less than 100 for nitrate nitrogen, or less than 443 for nitrate ion, or less than 607 for sodium nitrate.
3.1.2. Carbohydrate
Energy comes primarily from carbohydrates (sugars, starch and fiber) and fats in the diet. Lush leafy forage and browse, and tree leaves contain sufficient energy to cover the nutrient requirements of every goat on the farm. Feed grains that are high in energy are whole cottonseed, corn, wheat middlings, soybean hulls, soybean meal, molasses and corn gluten feed. Bacteria those are present in the rumen of goats ferment sugars, starches, fats and fibrous carbohydrates into volatile fatty acids. These acids are absorbed and used for energy. Fat is efficiently used for energy, but the amount that can be included in the diet is limited. Usually added fat should not represent more than 5% of a diet because it depresses ruminal fermentation. For example, if whole cottonseed (25% fat) is used as a supplement, it should not be more than 20% of the diet. Whole cottonseed also contains a good level of protein and phosphorous, and fed at 0.5 to 1.0 lb per day makes an excellent supplement to low quality forage. If the diet consumed by goats contains an excess of energy, that extra energy can be stored in the body as fat, mainly around certain internal organs. Energy
requirements for different physiological stages - maintenance, pregnancy, lactation and growth -vary. The maintenance requirement for energy remains the same for most goats except dairy kids; they require 21% energy higher than the average. It is important to feed high-energy rations at the time of breeding, late gestation and lactation. Lactating does have the highest energy demand
3.1.3. Protein
Protein is usually the most expensive component of the goat diet. As for energy, lush leafy forage and browse, and tree leaves contain sufficient protein to cover the nutrient requirements. Feed grains that are high in protein are whole cottonseed, soybean meal, wheat middlings and corn gluten feed. Protein is required both as a source of nitrogen for the ruminal bacteria and to supply amino acids for protein synthesis in the animal’s body. When the level of protein is low in the diet, digestion of carbohydrates in the rumen will slow and intake of feed will decrease. Inadequate levels of protein in the diet can negatively affect growth rate, milk production, reproduction and disease resistance because insufficient amino acids are getting to the intestines to be absorbed by the body. Unlike energy, excess of protein is not stored in the body of the goat; it is excreted in the urine as urea. Therefore, it is important for animals to have access to enough protein to cover their nutritional requirements.
Protein nutritional requirements vary with developmental and physiological stages and level of production.
Proteins are digested and broken down into amino acids and are eventually absorbed in the small intestine. Those amino acids are building blocks for body proteins (muscles). The rumen plays a major role in breaking down consumed protein into bacterial protein through bacterial fermentation. Feeds like forages, hays, pellets (alfalfa), barley, peas (screenings, whole, split), corn, oats, distilled grains and meals (soybean, canola, cottonseed meals) are common sources of protein for goat rationing.
According to Porsavathdy et al., 2017 reported when increased the CP % DM intake from 17.9, 19.7 and 21% were increased growth rate of goat (20 g/day, 31.8 g/day and 51.3 g/day) and better of DM feed conversion was increasing percentage of CP in diets. And founding from Sina et al., 2017: when goat fed cassava foliage as basal diet and supplemented with Brewer’s grain 5% of diet DM the total CP in DM intake of 26.6% was increased of growth rate of 161 g/day.
Table 4. Nutrient Requirements of Mature Does
Production Stage DMI, % of BW Nutrient Requirements, dry matter basis
% CP % TDN
Maintenance 1.8-2.4 7 53
Early gestation 2.4-3.0 9 - 10 53
Late gestation 2.4-3.0 13 - 14 53
Lactation 2.8 - 4.6 12 - 17 53 - 66
Source: Nutrient Requirements of Small Ruminants. National Research Council, 2007. Actual requirements will vary depending on breed, productivity and environment. DMI–dry matter intake, BW-body weight, CP-crude protein, TDN-total digestible nutrients.
3.1.4. Fat
Fats produce approximately 2.25 more time the energy than carbohydrates. In this respect, fats contain more energy per unit of weight. Within the animal body, fats surround internal organs, and appears in milk and meat. Fats can also be a source of energy for goats. Goats do consume some amount of fats while browsing. Excess energy produced by carbohydrates is stored in the form of fat especially around internal organs. The stored fat in the body is used during high energy needs, especially the lactation period. Supplying fats may not be a cost-effective idea for goat production.
3.1.5. Mineral and vitamin
Goats need certain minerals and vitamins for their maintenance as well as proper functioning of their physiological systems. Feeding of fat soluble vitamins (A, D, E, K) must be insured in a goat’s diet due to its inability to make these vitamins.
Rumen flora can make vitamin B in enough quantities needed for goat metabolism.
Vitamin C is essential for the immune system to work efficiently.
Minerals can be classified as macro and micro minerals. Calcium, phosphorus, magnesium, sodium, potassium, sulfur and chlorides are a few of the macro-minerals needed in a goat’s diet. Micro-minerals usually supplemented in goat rations are iron, copper, cobalt, manganese, zinc, iodine, selenium, molybdenum, and others. Feed tags report micro-minerals as parts per million (ppm) and macro-minerals on a percentage basis.
Feeding of calcium and phosphorus (2:1 ratio) is recommended for better structural and bone strength, while other minerals are necessary for other systems like nervous and reproductive. Minerals should be added into the feed keeping in mind the quality of forages as some forages can be high in some of the minerals and low in others. Free choice supply of loose minerals and salts always works well. If the
supplied minerals include enough salts then the producer should be careful in providing separate free choice salt.
It is important to feed enough copper (10-80 ppm) to goats as they have a tendency to be copper deficient. High levels of molybdenum in a goat’s diet can easily offset the copper levels in the body. Goats are not sensitive to copper, whereas in sheep even 20 ppm of copper can be very toxic. Selenium (0.1-3 ppm) is another mineral required for goats. Most of the soils in Manitoba are deficient in selenium, and forages from those soils may need selenium supplementation in the form of mineral supplements.