Nutrient Requirements of Beef Cattle

1. Nutrient Requirements of Beef Cattle Oklahoma Cooperative Extension Service Oklahoma State University

2. Dry Matter Intake is Influenced By: • Weight • Condition • Stage of Production • Forage Quality • Amount and Type of Supplement Provided • Environmental Conditions

3. Nutrition vs. “Fill” • Cattle have specific requirements for certain nutrients. • Protein, Energy, Minerals, Vitamins, Water • Intake on a forage-based diet is limited by capacity of the digestive tract. • Cattle can be “filled” to death on low quality roughages.

4. Forage Intake as a Function of Forage Quality

5. Dry Matter Intake Factors (cont.) Examples include: • Larger-framed cattle eat more forage than smaller-framed cattle. • Nursing cows eat more forage than “dry” cows. • “Fleshy” cattle eat 3-10% less forage than average to thin-fleshed cattle. • Cold stress increases intake, while heat stress decreases intake.

6. Protein: The First Limiting Nutrient • Composed of hundreds of amino acids. Provides for: Tissue growth and maintenance Immune system antibodies Blood proteins Enzyme system function Milk production Microbial synthesis • First nutrient limited by forage quality impact on microbial activity.

7. Feed the Rumen-Feed the Cow • Rumen microorganisms breakdown dietary protein for their own growth and development. • The microbes are digested in the small intestine of the ruminant. • Microorganisms need 7% crude protein for their maintenance and reproduction. • Limited CP for microbial synthesis, limits fiber digestion for the ruminant.

8. Metabolizable Protein • Characterizes protein degradability in the rumen, and utility in assuring optimal rumen function. • Degradable intake protein (DIP) is broken down in the rumen. • Undegradable intake protein (UIP) is not broken down in the rumen, but in the small intestine. • Metabolizable protein (MP) is the sum of microbial-derived protein plus UIP.

9. Protein Table Tips • Protein requirements expressed in pounds/day of crude protein, and percent of dry matter. • Replacement heifers need to gain 1-1.5 lbs./day to reach optimal breeding weight (60-65% mature weight) by 15 months of age. • Bred heifers need to gain 1 lbs./day from breeding to calving to reach 80-85% of their mature weight.

10. Table Tips (cont.) • The high protein requirement of heifers is due to their low dry matter intake capacity. • Growing heifers will generally need to be supplemented for adequate growth prior to their first breeding season. • Cow protein requirements increase during last 1/3 of gestation because the fetus obtains 2/3 of its growth at that time.

11. Table Tips (cont.) • Lactation is the most nutritionally stressful period for the cow, and therefore resquires neary twice the daily protein of dry cows. • Protein deficiency at calving can result in long intervals to rebreeding. • Larger-framed cattle require more protein for growth and maintenance than smaller-framed cattle.

12. Energy Requirements • Grazing • Movement • Fetal Development • Milk Production • Temperature Maintenance • Reproduction • Digestion • Voiding Body Wastes

13. Energy (cont.) • Heifers require additional energy for growth up to 4-5 years of age. • Thin cows require additional energy to restore body condition. • On forage-based diets, most of the energy comes from fiber digestion. • Inadequate protein in the diet for microbial synthesis means insufficient energy produced from decreased fiber digestion.

14. Energy Table Tips • Requirements expressed as: Total digestible nutrients (TDN) Net energy for maintenance (NEm) Net energy for gain (NEg) • TDN is the sum of the digestible starch, fiber, protein and fat in a feed with a correction factor of (2.25) for the high energy content of fat, and nitrogen-free extract.

15. Energy Table Tips (cont.) • TDN is expressed as percent of diet dry matter, as well as pounds/day required. • Net Energy requirements are expressed as mega calories/lb. of feed, and mega calories required/day. • Lactation represents the greatest need for energy beyond maintenance by as much as 50% more than when dry.

16. Energy Table Tips (cont.) • Due to the increased energy demand, lactating cows will consume more forage than dry cows. • First and second-calf heifers need additional energy compared to mature cows because they are still growing.

17. Energy Table Tips (cont.) • Inadequate energy for heifers during last 1/3 of gestation, and from calving to rebreeding can result in poor rebreeding performance. • Every 100 lb. increase in mature weight of cows over the 900 lb. cow will increase energy demand and the requirement for additional feed resources by 6-8%.

18. Summary • Beef cattle have specific requirements for protein, energy, vitamins, minerals, and water. • The nutrient requirements vary depending on such factors as: breed, gender, age, weight, stage of production, rate of growth, environmental conditions, etc. • The National Research Council has published information to enable beef cattle producers to determine the nutrient needs of their cattle, and design feeding regimes to meet those needs.

19. Questions?

20. Introduction • Define the subject matter • State what the audience will learn in this session • Find out any relevant background and interest of the audience

21. Agenda • List the topics to be covered • List the times allotted to each

22. Overview • Give the big picture of the subject • Explain how all the individual topics fit together

23. Vocabulary • Glossary of terms • Define the terms as used in this subject

24. Topic One • Explain details • Give an example • Exercise to reinforce learning

25. Topic Two • Explain details • Give an example • Exercise to reinforce learning

26. Summary • State what has been learned • Define ways to apply training • Request feedback of training session

27. Where to Get More Information • Other training sessions • List books, articles, electronic sources • Consulting services, other sources