Animal Nutrition

1. Chapter 6 of the National Range and Pasture Handbook Animal Nutrition

2. The Art of Grazing

3. Animals delight most to feed on fresh plants.

4. Cattle supplied with this kind of food would be quickly fatted

5. If a farmer divided his land into 15 to 20 equal divisions,

6. Stopped his beasts from roaming indiscriminately,

7. Put the whole number of his beasts into one of these divisions,

8. Have the numbers of beasts so great as to consume the best part of the grass in one day,

9. Give them a fresh park every morning to repeat the same repast,

10. Have so many parks as days required to advance the grass to the proper length after being eaten fare down,

11. So the first field would be ready to receive them after going over all the others,

12. So they might be carried round in a constant rotation.

13. James Anderson Scottish Agriculturalist, 1777

14. Animal Nutrition National Range & Pasture Handbook Chapter 6

15. Wait a minute….this is grass…… ….we’re eating grass??

16. General • “They should not provide technical advice or assistance to livestock producers on matters relating primarily to animal breeding, genetics, or animal health problems (except when animal health is related to forage resources)” page 6-1

17. Nutrient needs of animals • Protein • Required by rumen micro-organisms to digest forages and for muscling. If protein is lacking, intake will be reduced. • Carbohydrates (energy, DOM, TDN) • Serve as a source of energy for normal life processes (growth, maintenance & production) • Vitamins and minor elements

18. Nutrient needs of animals (cont.) • Minerals • Water • Quantity • Dairy cows 15-50 gallons/day • Beef cattle 6 - 18 gallons/day • Sheep and goats 1 - 4 gallons/day • Quality • Low quality water normally results in reduced water and feed intake

19. Energy • “The most important item in an animal’s diet and overall feeding standard is based on energy needs.” • Digestible energy (DE) • Metabolizable energy (ME) • Net energy (NE) page 6-2

20. High Energy Paddocks Perennial Ryegrass White Clover Timothy Meadow Fescue Chicory Fine-leafed Tall Fescue Milk Cows – 6-8 lb more milk/day Steers – 3 +lbsADG Young Heifers

24. Basal Metabolism Rate (BMR) • “...condition in which a minimal amount of energy is expended to maintain the body” • Factors affecting BMR & voluntary intake • Genetic factors • Physiological state • Environmental factors • Forage quality and quantity pages 6-3 to 7

25. Energy adjustments for cattle (table 6-2) • Breed Energy adjustment • Brahman - 0.20 • British + 0.00 • Dual purpose + 0.15 • Dual purpose cross with beef + 0.10 • Dairy + 0.20 page 6-3

26. Other Genetic Factors • Age of animal • as animal gets older, BMR declines • Sex of animal • Body composition of the animal • Body condition score • climatic conditions, stage of production, cow age, genetics, calving date, weaning date and forage management

27. Reference points for body condition score

28. Body Condition Score • Scale of 1-9 • 3 – Thin: Ribs & spine highly visible. • 4 – Borderline: 12th & 13th ribs visible. • 5 – Moderate: 12th & 13th ribs barely visible. • 6 – Good: Ribs fully covered. • 7 – Very good: Abundant fat cover on tail head.

29. 3

30. 4

31. 5

32. 6

33. 7

34. 5

35. 3

36. 6

37. 4

38. 7

39. Physiological state • Pregnancy • energy needs greatest during last third of term • Physical activity • energy cost higher for larger animals • slopes >15% requires 12 to 20 more energy • Lactation • high nutritional stress • peak lactation occurs in mature cows 30 to 45 days after calving then tapers off

40. Environmental factors • Thermoneutral zone • Cattle 41 - 68 *F • Calves 50 - 68 *F • Sheep 70 - 88 *F • Low temperatures • Wet and cold decreases intake due to less grazing time, dry and cold can stimulate intake • page 6-6

41. Environmental factors (cont.) • High temperatures • animals with low heat tolerance can have intake reduced as much as 35% at temps above 95degrees without night time cooling.

42. Forage quality and quantity • Forage intake is affected by: • Body weight • Forage quality • Forage quantity • Stage of production • Supplemental feeding strategy • Environmental conditions

43. Forage quality • As forage quality declines, intake is reduced • Digestibility normally controls intake (and selection) when forage quantity is not limited • If nutritional level of vegetation is low, more pounds of forage are needed per day to support the animal

44. Forage quality (cont.) • The stomach of the domestic cow reaches full size by the time the animal is 4 - 5 yr.. • The size of the stomach is dependent upon the forage quality the animal grazes during this growth and development period. • low forage quality = 40 - 50 lbs./day air dry • high forage quality = 20 - 30 lbs./day air dry • Gut expansion may take as much as 1 year

45. 1954

46. Same Field 50 Years Later - 2004

47. Forage quantity • Intake declines as forage availability decreases. • Animals increase grazing time to adjust for low forage quantity. • What is the forage quantity threshold? • When < 1000 lbs./ac intake declines by 15%. However, studies vary greatly with reports ranging from 120 lbs./ac to 5,000 lbs./ac

50. Balancing animal numbers and available forage • One animal unit (AU) • A 1000 LB cow with a calf < 6 months old • One animal unit month (AUM) • Amount of forage required to support one AU for one month • NRCS will use 30 lbs. of air dry forage/day (3.0% of body weight)