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Afghanistan Beef Introduction. Jeff Lehmkuhler, PhD Extension Beef Specialist University of Kentucky. Function of Rumen. Provide an environment for symbiotic growth of microflora to ferment feedstuffs Storage allowing a large quantity of fibrous feed to be consumed in short period of time
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Afghanistan Beef Introduction Jeff Lehmkuhler, PhD Extension Beef Specialist University of Kentucky
Function of Rumen • Provide an environment for symbiotic growth of microflora to ferment feedstuffs • Storage allowing a large quantity of fibrous feed to be consumed in short period of time • Absorption of fermentation endproducts
Microorganisms in rumen Bacteria, protozoa, fungi, yeast Microbes may provide ~85% of the energy and protein In ruminants Carbohydrates VFA Acetate Propionate Butyrate In monogastrics Carbohydrates Glucose
Functional Classes of Microbes Fiber Digesters Starch Digesters Protein Digesters * Population shifts as the diet changes. Can affect overall digestion, founder, etc. * Transition cattle from forage to grain slowly
Functions of the Rumen Microflora • Convert cellulose (large amounts) into useable energy products • Mammals do not produce cellulase enzyme • Utilize Non-Protein Nitrogen (NPN) to form amino acids • Synthesize B Vitamins and Vitamin K
Essential Nutrients • Water • Energy • Protein • Minerals • Vitamins
Water • Water Intake Drives Feed Intake
Water • Factors affecting water intake • Temperature • Feed moisture • Body size • Production status
Macro Salt (NaCl) Calcium (Ca) Phosphorous (P) Magnesium (Mg) Potassium (K) Sulfur (S) Micro Copper (Cu) Selenium (Se) Zinc (Zn) Manganese (Mn) Cobalt (Co) Iron (Fe) Chromium (Cr) Molybdenum (Mo) Iodine (I) Nickel (Ni) Macro & Micro Minerals
General Functions of Minerals • Nutrient Metabolism • Nerve function • Reproduction • Immune Function
Parameter Evaluated Affects Animals Mineral Requirement Immunity > Fertility > Growth > Maintenance
Phosphorus • Deficiency impacts reproduction • Diet contains less than 0.15% Phos • Pica – chewing of bones, botulism • Bone meal, steamed bones • Not allowed in US for fear of BSE
Magnesium • For cows pre- and early lactation • When conditions for grass tetany exist • Winter tetany can occur • Poor quality feeds w/ grain or Greenchop / Haylage • High K+ and Low Ca++ & Mg++ • > 22 grams per head daily lactating cows
Energy • Result of CHO and Lipid metabolism (eg. Converting hay to VFA) • Requires the majority of feed intake • Most commonly deficient nutrient for the brood cow • Often expressed as TDN = Total Digestible Nutrient
Net Energy Scheme 1 kg TDN = 4.4 Mcal DE
Estimated Net Energy Requirementsfor 2-, 3-, and 5-year old Cows Breeding Season Calving Wean Mcal/d Months Since Calving 1996 Beef NRC
Factors Affecting Efficiency of Energy Utilization • Breed • Genetic ability to milk • Actual level of milk production • Body composition
Protein • Cattle have 2 protein requirements • N needs of rumen bacteria • Amino acids of the animal • Degradable Intake Protein (DIP) • Breakdown in rumen and supply N to bacteria • Undegradable Intake Protein (UIP) • Escape rumen, digested in gut, supply AA
Protein Needs for Cows 30 lb peak milk production
Vitamins • Fat Soluble • A, D, E and K • Water Soluble • B complex and C • For the cow, A is the only vitamin deficient under normal circumstances
Vitamins • Vitamins of B-complex and K are made in rumen. • D is made in skin from sunlight. • C is synthesized in tissue • E is contained in most feeds
Vitamin A • Plants contain beta carotene, not vitamin A • Cattle convert beta carotene to vitamin A • Factors reducing the conversion to A • Stress • Forage Maturity, Storage Time and Weathering
Vitamin A • Cattle store A in the liver for later use, thus a mega-dose can be fed or injected • When fed, 50 to 70% of vitamin is destroyed in the rumen. Must be considered when determining daily dose to provide
Vitamin E • Generally adequate in pastures and hay • May become deficient in extreme drought or long feeding of very mature forage • Necessary for good immune function
B-complex Vitamins • Weaning stress or fescue toxicosis feed intake and rumen function which may cause insufficient B vitamin production • Niacin may feed intake in receiving calves • Thiamin may fescue toxicosis symptoms • Responses to Vit B supplements VARIABLE
Body Condition Score (BCS)in Beef Cows • Highly related to reproductive efficiency • Calving time BCS very important • Thin cows at calving have days return to heat and pregnancy rate • BCS 1-9
BCS Maintenance After Calving and Days Return to Heat Cows calving in adequate BCS but rapidly losing condition after calving take longer to return to heat than cows maintaining BCS after calving.