Nutritional Requirement of Livestock

The essential nutrients required by grazing animals are water, energy, protein, minerals, and vitamins. These nutrients are needed to maintain body weight, growth, reproduction, lactation, and health.

Water Water is essential for all livestock, and producers should plan for an adequate supply of clean water when starting a livestock production. The amount of water required depends on the physiological stage of the animal and the climate. Lactating animals require more water, and the amount of water required increases as atmospheric temperature increases. Water availability should be closely monitored because a deficiency in water will result in death much faster than a deficiency of any other nutrient.

Protein Ruminants have the ability to convert low-quality protein sources to high-quality proteins through bacterial action. Microbial protein synthesis is sufficient to supply the protein needs as long as adequate precursors are supplied, except during lactation for high milk producing animals. Protein is required by all livestock animals for tissue growth and repair

Energy Insufficient energy probably limits the performance of livestock more than any other nutritional deficiency. Energy requirements vary greatly with the stage of production, and adequate amounts of energy are extremely important during late gestation and early lactation. Energy deficiencies can cause reduced growth rate, loss of weight, reduced fertility, lowered milk production, and reduced wool quantity and quality. Energy is obtained from carbohydrates in the plant material and can be stored in the form of body lipids. However, heavy demands against fat stores as an energy source to meet daily needs may delay estrus and reduce conception in breeding females. Live weight gain can only occur after the animal’s energy requirements for maintenance and lactation are met.

Vitamins and Minerals Ruminants require all the fat-soluble vitamins (A, D, E, and K), but they can synthesize the B vitamins in their rumen. Normally, the forage and feed supply contain all essential vitamins in adequate amounts, except vitamin A which is obtained as carotene from green plants and is often deficient in dormant forage. However, vitamin A can be stored in the liver in amounts sufficient to last considerable periods of time, such as winter dormancy or prolonged drought. Salt is essential for many body functions and important to maintain intake of feeds and water. Calcium and phosphorus are needed to maintain growth, feed consumption, normal bone development, and reproductive efficiency. Other nutrients and minerals such as vitamin E and selenium are important for the maintenance of healthy bodies and reproduction.