1. Nutrient Requirements of Beef Cattle - MP 391 Overview

2. Nutrient Classes Carbohydrates Fats Protein Minerals Vitamins Water ENERGY (calories)

3. Factors Affecting Nutrient Requirements Age Size Breed (Brahman influence, maternal) Stage of Production (growing, gestating, lactating) Level of Production (milk, growth rate) Environment Thermal stress (insulation)

4. Protein Requirements commonly expressed as Crude Protein (N x 6.25) Growing/finishing diets may be segragated into Rumen degradable and rumen undegradable protein.

5. Example Cow CP Requirement Page 6. MP 391

6. Example Cow CP Requirement

7. Energy Commonly expressed as TDN for beef cows TDN = digestible fat + digestible carbohydrate + digestible protein May also be expressed as Calories for growing cattle Net Energy for Maintenance (NEm) Net Energy for Gain (NEg)

8. Example Cow TDN Requirement Page 6. MP 391

9. Example Cow TDN Requirement

10. Example NE Requirement for Growing Calf

11. Dry Matter Intake Intake expressed on DM basis to account for differences in feedstuff moisture Affected by Size (Body weight) Stage of pregnancy Diet digestibility Environment Thermal stress Housing conditions Anti-quality factors Palatability Negative feedback mechanisms (toxins)

12. DMI As Affected By Cow Size and Diet Quality

13. Example Energy Supply for Cows Diet Digestibility50% TDN60% TDN70% TDN DMI (1100 lb cow)232527 TDN (lbs)11.51519 Late Gestation (11.7 lb) Early Lactation (14.5 lb) Mid Lactation (13 lbs)

14. Example Energy Supply for Growing Calves TDN67% NEm (Mcal/cwt)70 NEg (Mcal/cwt)43 DMI (lbs)12.5 NEm required (Mcal)4.5 Feed DM available for maintenance (lbs)(4.5 / 0.70) = 6.4 Feed DM available for gain (lbs)(12.5 – 6.4) = 6.1 NE available for gain (Mcal)(6.1 * 0.43) = 2.62 Expected ADG1.7 lb/d