Nutrient Requirements for Body Functions

1. Nutrient Requirements for Body Functions Topic 3041 Nutrients and Nutrient Requirements Developed by Amanda R. Moore

2. Definitions Requirements for: Body Maintenance Growth Fattening Reproduction Lactation Egg Laying Wool Production Work Overview

3. Definitions • Metabolism • All the chemical and physical properties that take place in the body • Anabolism • Metabolism that builds tissue • Catabolism • Metabolism that breaks down materials

4. Nutrient Requirements for Body Maintenance • Body Maintenance: A condition in which the body is maintained without an increase or decrease in body weight, and with no production or work being done. • Examples: • Body tissue repair • Control of body temperature • Energy to keep vital organs functioning • Water balance maintenance

5. Body Maintenance • Approximately 50% of feed is used to fill the maintenance requirement • This must be met before supplying nutrients for other functions • Maintenance needs are related to body size

6. Body Maintenance • Maintenance requirement in relation to weight can be expressed as Wt.75 • Ie:If a 500-lb animal needs 15 lb of feed per day for maintenance, a 1,000-lb animal of the same type would not require twice as much feed as the first. Instead: 1000.75 shows that this animal requires 1.7 times as much as the smaller animal = (15lb x 1.7 = 25lb)

7. Nutrient Requirements for Growth • Growth is the increase in protein over its loss in the animal body. It occurs by increases in cell numbers, cell size or both • Growth requires energy, protein, minerals, vitamins and energy • Young animals require more protein in order to build muscle and grow • Mongastric animals also need certain amino acids for proper growth

8. Growth • Young animals also need calcium and phosphorus, salt or a normal sodium level, any mineral that may be deficient in the area the animal lives • Iodine and Selenium require special consideration • Iodine deficiency in the fetus prevents thyroxine from being produced, causing goiters and eventual death in newborns • Selenium deficiency may cause white muscle disease in newborns

9. Growth • Vitamins are also required by growing animals • Must be supplied to pigs and poultry through feeds (usually vitamin D) • Vitamin A is usually the only vitamin commonly fed to ruminants • Energy is required to sustain growth, metabolic rate and activities • Can be supplied by feeding corn, barley or wheat

10. Nutrient Requirements for Fattening • Fattening: Storing of surplus feed energy as fat • Results from excess energy from carbohydrates, fats or protein beyond the the maintenance requirements

11. Nutrient Requirements for Reproduction • Two categories of requirements: • Gamete production • Fetal growth in the uterus • Fetus requirements are much greater in the last trimester of pregnancy • Nutrition of the female must not be inadequate during pregnancy

12. Nutrient Requirements for Lactation • Milk production requires considerable protein, minerals, vitamins and energy • The need for protein is greater because milk contains more than 3% protein • Calcium and phosphorus are the two most important minerals needed for lactation. If absent, may result in decreased lactation, disease or even death

13. Lactation • Energy is the most vital requirement for the production of a large quantity of milk • High producing dairy cows may need up to four times the energy of a nonlactating cow of the same size.

14. Nutrient Requirements for Egg Laying • Egg layers are usually fed free choice (as much as they can eat) • It is important that rations have adequate concentrations of energy, protein, vitamins and minerals

15. Nutrient Requirements for Wool Production • These are in addition to nutrients needed for maintenance, growth and reproduction • Wool fibers are primarily protein, the ration should be adequate in protein • Shearing may cause an increase in energy requirements

16. Nutrient Requirements for Work • Large amounts of energy beyond the maintenance needs • If energy is not sufficient in the ration, the animal will begin to use body fat stores to provide the additional energy needs

17. Resources • Taylor, Robert E. and Field, Thomas G. 1998. Scientific Farm Animal Production, Sixth Edition. New Jersey:Prentice Hall Publishing. • Desert Roses[online]: www.ag.arizona.edu/desert_roses, 3/14/01