FUNCTIONS OF NUTRIENTS

Transcription

1 FUNCTIONS OF NUTRIENTS

2 All animal use a portion of their absorbed nutrients to carry on essential functions, such as body metabolism and maintaining body temperature and the replacement and repair of body cells and tissues. These uses of nutrients are referred to as maintenance. That portion of digested feed used for growth, fattening, or the production of milk, eggs, wool, and work is known as production requirement. Another portion of nutrient is for the development of the fetus and is referred to as reproduction requirement.

3 Maintenance requirement Defined as the combination of nutrients which without any gain or loss in body weight or any productive activity. Energy is the primary nutritive need for maintenance. (1) heat to maintain body temperature, (2) keep vital body processes functional, (3) energy minimal movement, (4) to repair damaged cells and tissues and to replace those which have become nonfunctional.

4 Nutrient needs are minimal during maintenance, it is noteworthy that ⅓ to ½ of the feed consumed by animal as a whole is used to meet the maintenance requirement. The higher the production, the smaller the production of nutrients needed for maintenance.

5 Factors affect the amount of the necessary for maintenance (1) exercise, (2) weather, (3) stress, (4) health, (5) body size, (6) temperament, (7) individual, (8) level of production, (9) lactation. The first four are external factors are subject to control to some degree through management and facilities. The others are internal factors are part of the animal itself.

6 1.Exercise: The additional movement of animal increases the energy requirement for maintenance. 2. Stress: Stress of any kind increases maintenance requirement.

7 3.Weather: Maintenance requirement of animal increase as temperament, humidity, and movements depart from the comfort zone. Critical temperament is that temperament at which the heat created by digestion and, body metabolism just equals that which the animal dissipates by convection, evaporation, radiation, and conduction. The critical temperament, comfort zone, and optimum temperament vary with different species, ages, breeds, and the physiological and productive status of animals. For example, the comfort zone of newborn lambs is 75 to 80, mature sheep is 45 to75. Animals that consume large quantities of roughage produce more heat during digestion; a different critical temperament than the same animals on a highconcentrate ration.

8 4.Body size: Body size was once used as a basis for determining the maintenance requirement of animals. Body surface was found to be a better reference point for metabolism than body weight. The most accurate measure of metabolic size of an animal is W.75, this means that the smaller animal has a higher rate of metabolism per pound of body weight than a larger animal.

9 5.Lactation: The maintenance requirements of lactating females of all species are higher than those of dry, nonpregnant females. The maintenance requirement is approximately 10 percent higher than those of dry, nonpregnant females. This is attributed to (1) the increased secretion of thyroxin in lactating cow in a faster heartbeat-increased basal metabolism rate; (2) the approximately 400 lb of blood which must be pumped through the udder to supply the raw material for 1 lb of milk.

10 6.Growth Growth may be defined as the increase in size of bones, muscles, internal organs, and the other parts of the body. Factors affecting nutritive needs for growth The nutritive needs for the growth vary with age, breed, sex, rate of growth, and health.

11 (1) Age In comparison with older animal, young animals generally (1) consume more feed per unit of body weight; (2) utilize feed more efficiently, in pounds of feed eaten per pound of body gain; (3) have a higher requirement for protein, energy, vitamins, and minerals per unit of body weight; (4) require a more concentrated and more easily digested diet; and (5) are more subject to nutritional deficiencies. (2) Breed Larger breeds of all species grow more rapidly than smaller breeds and have a higher nutrient requirement.

12 (3) Sex (1) Male gain more rapidly than female and have a higher feed requirement; (2) uncastrated males use feed more efficiently for body weight gains than female, because of the higher water and protein content and the lower fat content of the increased body weight; (3) mature average size is larger in male than in female; (4) females reach maturity faster than males.

13 (4) Rate of growth Rapid gains call for more nutrients. In turn, this necessitates high-energy, palatable, well-balanced rations. Fast gains are efficient gains; when animals grow at maximum rates, they require fewer nutrients and pounds of feed per pound of gain.

14 7. Egg production The nutritive needs for commercial egg production include those for maintenance of birds, growth of pullet layers, and the formation of egg. The standard-weight egg contains about 95 calories of gross energy, 7.5 grams of crude protein, and 2 grams of calcium. For high hatchability and good development of young, breeders require greater amounts of vitamin A, D, E, B12, riboflavin, pantothenic acid, niacin, and of the mineral manganese.

15 8. Lactation The nutrient needs for lactation depend on the amount and composition of milk secreted.