Primary Goat Feed Nutrition
Generally, goat feed nutrients are divided into six groups. Following is a brief discussion of these nutrients:
Protein is the only nutrient that contains nitrogen. Protein quality - a term referring to the amino acid content - has no significance in ruminant nutrition, except at exceptionally high levels of milk production. Rumen microorganisms manufacture their own body protein, consisting of all the necessary amino acids, which are later digested by the host animal.
Protein makes up the basic animal tissue of the body and is vital for growth, milk production, disease resistance, reproduction, and general maintenance. The body has very little if any excess protein. Mostly, the nitrogen is eliminated by the kidneys and the rest is burned as energy. Since protein is generally the most expensive part of the ration, it is costly to feed more than what is needed. Protein requirements vary between 12 and 16 percent of the ration dry matter with the latter needed for high milk production.
Urea and other non-protein nitrogen products can be utilized by the microorganisms of the rumen for the production of protein. They are not generally recommended for goats because they are very selective in their diets.
All discussions of nutrition seem to begin with energy, probably because this is the best defined requirement of farm animals and is expensive. Most of the goat's energy comes from the breakdown of the fiber of forages, while the remainder comes from the burning up of concentrate starches and fats. Over a longer period of time effects such as retarded growth, delayed puberty, and decreased fertility will become apparent.
Energy is measured in two different ways by the feed industry. The first and more established method is by Total Digestible Nutrients (TDN). As the name suggests, the TDN consists of the sum of the digestible carbohydrates, digestible protein, and digestible fats (multiplied by 2.25 since fats contain that much more energy than protein or carbohydrates). The TDN system takes into consideration only one nutrient loss - feces. For this reason, the net energy system is gaining in popularity. This system considers energy that is lost in the feces, urine, gases, and the work of digestion. In recent years this system has been even more refined to account for varying energy utilization needs for body maintenance, weight gain, or milk production.
Many minerals are required by the goat. Most can be obtained from good forage and a regular concentrate mixture. The major minerals of concern are calcium, phosphorus, and salt, which are usually added to the ration either in the grain mix or by free-choice feeding. Goats do not consume minerals free choice according to their needs. It is, therefore, recommended that minerals be force-fed through the grain mixture or mixed with a succulent feed like silage or greenchop, if possible. The ratio of calcium to phosphorus is important and should be kept around 2:1. If these minerals must be fed free-choice, such as to dry goats and yearlings, a good mixture is one containing equal parts of salt and dicalcium phosphate, or a similar commercial mix.
Vitamins are needed by the body in small amounts. Since all the B vitamins and vitamin K are produced in the rumen and vitamin C is manufactured in the body tissues, the only vitamins of concern in ruminant nutrition are vitamins A, D, and E. During the late spring, summer, and early fall the animals can get all they need from green pastures and plenty of sunshine. In addition, they can store a good supply of these vitamins to carry them into the winter months.
Nevertheless, it is a good idea to add these vitamins at the rate of 6 million units of vitamin A and 3 million units of vitamin D to each ton of grain mix during the winter months as an added precaution since they are not very expensive.
Fats are of little importance in the ruminant ration. Practically all feeds contain small amounts of fat, and added levels are not practical. A level of 1.5 - 2.5 percent in the grain mixture is normal.
This is the least expensive feed ingredient, yet a deficiency will affect milk production more quickly than the lack of any other nutrient. Water is not only the largest single constituent of nearly all living plant and animal tissue, but it also performs exceedingly important functions during digestion, assimilation of nutrients, excretion of waste products, control of body temperature, and the production of milk. Ready access to water is important. Goats with water constantly available have been shown to produce more milk than those watered twice daily and over 10 percent more than those watered only once per day.