Animal nutrition on the rangeland By Dr A. Riasi PhD in Animal Nutrition and Physiology

1. Animal nutrition on the rangeland By Dr A. Riasi PhD in Animal Nutrition and Physiology (Isfahan University of Technology)

2. What is the role of energy in animal nutrition? • Energy is the single most important dietary component for an animal after water. • Energy is derived from carbohydrates, fats, proteins, and from the animal’s body reserves. • Energy intake maintains body functions and facilitates growth and development, including: • Reproduction • Lactation

3. What is the role of energy in animal nutrition? • Energy is supplied to ruminants by highly digestible plant cell contents and a portion of the less digestible plant cell wall fraction. • The hierarchy of energy digestion begins with gross energy.

4. GROSS ENERGY Feces DIGESTIBLE ENERGY Urine & Gas METABOLIZABLE ENERGY Heat increment NET ENERGY Maintenance Gain Reproduction Milk Production

5. Determining Caloric Energy

6. Steps in determining calories • Prepare sample (grind, pellet, place in bomb) • Wire bomb and charge with Oxygen • Place in calorimeter in known amount of H2O • Measure initial temperature • Ignite • Measure final temperature

7. Calculations • 1 calorie = energy to raise 1 g H2O 1° C • 1000 cal = 1 Kcal • (In humans 1 Calorie = 1 Kcal, animal nutritionists don’t use Calorie vs calorie) • Temp rise X g H2O = calories in sample • Cal in sample X amount of feed = Cal in feed • same for feces

8. Calculations • Calculate the total calories (or Kcal) (per day) eaten and excreted (in feces, urine). • Calculate DE, ME, Net E (must know the endogenous contribution in Kcal/Kg and % • For Kcal/Kg divide the Kcal of interest by Kg consumed • For %, divide the Kcal of interest by Kcal of feed consumed (times 100).

9. TDN • Total Digestible Nutrients • Forget that, I consider it a misnomer • It is really: • An ENERGY INDEX on a carbohydrate equivalent basis • Calculated from proximate analysis

10. Calculating TDN • % CP X Digestibility = x • % EE X 2.25 X Digestibility = x • % CF X Digestibility = x • % NFE X Digestibility = x • ------ • SUM = TDN TDN

11. Example • Water 12 • Crude protein 12.5 • Ether Extract 4 • Crude Fiber 10 • Ash 2 • NFE 59.5

12. Example • Water 12 • Nitrogen 2 (2*6.25) 12.5 .80 • Ether Extract 4 .75 • Crude Fiber 10 .40 • Ash 2 • NFE 59.5 .80 digestibility

13. Example • Water 12 • Nitrogen 2 (2*6.25) 12.5 .80 = 10 • Ether Extract 4 * 2.25 * .75 =6.75 • Crude Fiber 10 .40 = 4 • Ash 2 • NFE 59.5 .80 = 47.6 • ----------------- • TOTAL (TDN) 68.35 digestibility

14. What is the role of protein in animal nutrition? • Crude Protein is calculated from the nitrogen content of the forage. • The CP value is important since protein contributes energy, and provides essential amino acids for rumen microbes as well as the animal itself. • Protein in forages is most correlated with forage maturity, as more mature forages have a lower percentage of crude protein.

15. Kejeldahal method

16. Kejeldahal method Digestion step Digestion is accomplished by boiling a homogeneous sample in concentrated sulfuric acid. The end result is an ammonium sulfate solution. The general equation for the digestion of an organic sample is shown below:

17. Kejeldahal method Distillation step Excess base is added to the digestion product to convert NH4 to NH3 as indicated in the following equation. The NH3 is recovered by distilling the reaction product.

18. Kejeldahal method Titrationstep Titration quantifies the amount of ammonia in the receiving solution. The amount of nitrogen in a sample can be calculated from the quantified amount of ammonia ion in the receiving solution. There are two types of titration—back titration and direct titration. Both methods indicate the ammonia present in the distillate with a color change.

19. Kejeldahal method In back titration (commonly used in macro Kjeldahl), the ammonia is captured by a carefully measured excess of a standardized acid solution in the receiving flask. The excess of acid in the receiving solution keeps the pH low, and the indicator does not change until the solution is "back titrated" with base.

20. Kejeldahal method

21. What is the role of protein in animal nutrition? • Cattle require two types of protein in their diet: • One type is degraded in the rumen (RDP) • Some of the protein in the diet does not undergo degradation in the rumen, but passes straight to the abomasum or stomach for digestion (RUP)

22. What is the role of protein in animal nutrition? • Bypass protein is important because a large percentage of the rumen degraded protein is absorbed as ammonia and, if in high concentrations, can be lost through the urine as urea. • In forages, roughly 20 to 30 percent of the protein taken in by the animal is bypassed to the intestines.

23. What is the role of protein in animal nutrition? • Lactating or growing cattle generally require 32 to 38 percent of their total protein intake to be in the undegradable form (Muller, 1996). • High-quality pastures can meet almost all the needs of high-producing livestock.

24. What is the role of protein in animal nutrition? • Some concentrate are high in bypass protein: • corn, • cottonseed meal • linseed meals, • brewers dried grains, • corn gluten meal, • distillers dried grains, and • fish meal

25. What is the role of protein in animal nutrition? • The microbial degradation of protein is an energy-dependant process. • Carbohydrates are the energy-yielding nutrients in animal nutrition and are supplied by the production of volatile fatty acids in the rumen. • Generally more microbial protein is synthesized from green forage diets than from hay or mature forage diets.

26. What is the role of protein in animal nutrition? • Ruminant animals need approximately 65 to 68 percent of the protein to be rumen degradable for adequate rumen function and the development of microbial protein. • Much of the rumen degraded protein is absorbed as ammonia and excreted out of the body via the urine, and is therefore a waste of protein.

27. What is the role of protein in animal nutrition? • Some animal nutritionists suggest that bypass protein has been overemphasized. • We must remember that ruminant animals evolved in symbiosis with rumen microorganisms in a grassland environment, and they are inherently adapted to this function.