Lecture49 - Lecture 49 Lecture 49 Minerals Minerals...

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Unformatted text preview: Lecture 49: Lecture 49: Minerals Minerals Minerals Important for soil, plants, and animals Type of soil pH of the soil Plant species and maturity Fertilization Typically supplement with ad libitum, loose mineral mix for grazing beef EMFS Classes of Minerals Classes of Minerals Macro minerals Calcium Phosphorus Potassium Sodium Sulfur Chlorine Magnesium Trace minerals Cobalt Copper Chromium Iron Iodine Manganese Molybdenum Selenium Zinc Plus some newer ones Macro Minerals Macro Minerals Mineral % of element in body Calcium 1.33 Phosphorus 0.74 Potassium 0.19 Sodium 0.16 Sulfur 0.15 Chlorine 0.11 Magnesium 0.04 Ca and P Ca and P Ca represents 46% of the body’s total mineral content while P represents 29% Bones are the obvious site of storage 99% of total Ca 80­85% of total P Typically a ratio of 2:1 (Ca:P) is thought to be healthy Less of a concern for ruminants Tolerate up to 6:1 But if < 1:1 urinary calculi Calcium Calcium Sources Requirements Absorption Circulation Deficiency Sources of Ca Sources of Ca Limestone Ca carbonate (CaCO3) 80% of Ca in earths’ crust so low $$ Dicalcium phosphate AKA­ DiCal or dolomite (CaHPO4*2H20) Higher bioavailability then limestone Requirements of Ca Requirements of Ca Breed Class Requirement Beef All Classes 0.16 – 1.53% Dairy Lactating 0.43 – 0.60% *Widely variable depending on breed, sex, age, and stage of production ** Taken from McDowell, 2003 Absorption of Ca Absorption of Ca Typically only 30­50% of ingested Ca is absorbed Small amount absorbed from the rumen Most absorbed from small intestine Active (Vit D dependent) and passive Favored by acid duodenum and jejunum Amount absorbed depends on needs Higher for lactating and/or growing animals High producing dairy cows can be in a neg. Ca balance for 1st 8 months of lactation Calcium Circulation Calcium Circulation Only 1% circulating in the body for: Ca circulation regulated by 3 things: Calcitonin ­ ↓ Parathyroid hormone ­ ↑ Coagulation of blood Stimulation of nerves and muscles Electrolytes acid base balance Active form of Vit D (1,25­(OH)2D) ­ ↑ Plasma [Ca] maintained closely 9.5 mg/dl Calcium deficiency Calcium deficiency Largely deficient in grain, adequate in forages Grains: 0.2­0.10% Mature grass forages: 0.31­0.36% Higher [Ca] in legumes then grasses 1.2­1.7% Greater issue for animals consuming all concentrate diets In young animals a deficiency in Ca results in rickets Osteomalacia in mature animals Milk fever in dairy­72 h postpartum Rickets Rickets Phosphorus Phosphorus Sources Requirements Absorption Circulation Deficiency Sources of P Sources of P P supplementation limited by fluorine Must have defluorinated sources Dicalcium phosphate In liquid feeds Ammonium polyphosphate Phosphoric acid Requirements of P Requirements of P Breed/Class Requirement (% of ration DM) Dairy Cattle Growing heifers & bulls Growing .26 Dry, pregnant cows Dry, .26 Lactating cows Lactating .31 to .40 Beef Cattle Beef Pregnant yearling heifers Pregnant .19 to .22 Dry, pregnant mature cows Dry, .20 to .22 First calf heifers, lactating First .23 to .25 Absorption of P Absorption of P Typically 70­80% of ingested P is absorbed Most absorbed from small intestine Active and passive Unlike CA, amount absorbed not related to the needs of the animal Influenced by: Source, intestinal pH, age, parasitism, and other minerals (Fe, Al, and Mg) Phytate P P in the body P in the body P not a closely regulated as Ca Some control of intestinal absorption by Vit D Ruminants have a high renal threshold for P not readily excreted in the urine Recycled through saliva main contributor of P to the gut Involved in nearly every aspect of feed metabolism! Deficiency of P Deficiency of P Described as early as 1785 Typically deficient in forages Soil­plant­animal interactions Acid soil condition Ca:P greater then 6:1 may confound P deficiencies Signs include: Anorexia Pica Bone chewing Leading to botulism ↓ feed efficiency disturbance in energy metabolism ...
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