Mineral Nutrition of the Goat

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Mineral Nutrition of the Goat

• Joseph Tritschler
• Small Ruminant Specialist
• Virginia State University

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Nutrients necessary for ruminant animals

• Water
• Energy (carbohydrate, protein, fat)
• Protein (amino acids)
• Minerals (salt, macrominerals and trace)
• Vitamins (A, D, E, K but not Bs or C)
• (Fiber for GI function)
• (Essential Fatty Acids)

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Essential Minerals of Animals

• Macrominerals
• Salt (NaCl)
• Calcium (Ca)
• Phosphorous (P)
• Magnesium (Mg)
• Potassium (K)
• Sulfur (S)

• Microminerals
• Iron (Fe)
• Iodine (I)
• Copper (Cu)
• Molybdenum (Mo)
• Cobalt (Co)
• Manganese (Mn)
• Selenium (Se)
• Fluorine (F)

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Macromineral Requirements(percent diet DM)
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Sodium and Salt Deficiency

• Salt (sodium) always inadequate in forages
• Sodium requirement higher than chlorine
• Low salt decreases growth
• Inappetence
• Salt intake data (sheep)
• 0.5 salt in total mixed rations (0.2 Na)
• 1.0 or more in concentrate supplements
• Free choice lambs eat 5 10 g/d ewes eat 15
  30 g/d
• Range ewes eat less in salt licks

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Calcium and Phosphorous

• Critical for milk production bone growth
• Calcium deficient in concentrate feeds
• Rapid need for Ca in lactation
• Inability to mobilize Ca leads to milk fever
• Legumes lined pastures good Ca sources
• Phosphorous deficient in forages
• Very widespread mineral shortage
• Poor growth, lower reproductive performance

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Calcium Phosphorous Ratio

• Calcium to phosphorous best in a ratio
• Absorbed and mobilized together
• Ideal ration 1.51 to 21 (CaP) (can be higher)
• Urinary calculi in breeding male goats
• Observed with high phosphorous
• Observed with low CaP ratios
• Usually breeding males in confinement
• Related to low potassium and magnesium levels
• Ration additives are available (KCl, NH3Cl)

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Magnesium and Grass Tetany

• Physiologically a Mg deficiency
• Occurs under periods of stress
• Lactating cows starting spring grazing
• Does (and ewes) not as problematic as cows?
• Associated with excess N K fertilization
• Form insoluble Mg complex in rumen
• Forage analysis may indicate adequate Mg
• Use ratio of K / (Ca Mg) (below 2.3
  milliequivalents)
• Mg generally lower in cool-season grasses at
  lower temp.
• Best prevented through management
• Stress reduction (overworking animals)
• Mg fortified supplements in the critical period
  (spring)
• Dolomitic limestone contains both Ca Mg

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Potassium and Sulfur

• Not commonly deficient
• Potassium possible low in concentrates
• Sulfur possibly low in highly leached soils
• High K ( N) fertilization
• Increased grass tetany problems

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Lime, Fertilizer, Cost and Environmental Health

• Limestone (Ca and Mg (dolomite))
• Reduces soil acidity (needed for legumes)
• Usually more limiting than fertilizer
• Fertilizer (N, P and K manure also)
• Essential for plant growth
• N and P excess are environmental problems
• N and P are relatively expensive
• Fertilizer, Manure Minerals
• Regulations to control environmental (water)
  quality

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Micromineral Requirements(ppm or mg/kg diet DM)
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Copper, Cobalt, Selenium

• Trace minerals most commonly deficient
• Often deficient in same location
• Areas include eastern U.S.
• Molybdenum increases copper requirement
• One negative aspect of liming
• Copper and selenium potential toxicities
• Deficiencies are more common

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Micromineral Tolerances (ppm or mg/kg diet DM)
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Copper Sheep and Goats

• Copper requirements are the same
• Cattle, sheep and goats
• Requirement about 10 ppm
• Copper tolerance lower is sheep
• All ruminants have relatively low tolerance
• Sheep tolerate 25 ppm
• Cattle tolerate 100 ppm
• Goats tolerate at least 40 ppm

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Mineral Summary

• Goat requirements
• Relatively little research
• Requirements extrapolated for cattle sheep
• Relative susceptibility to nutritional disorders
• Milk Fever dairy cattle than dairy goats
• Grass Tetany beef cattle than sheep
• Pregnancy Toxemia sheep and goats
• Copper Toxicity sheep than goats and cattle
• Overeating Disease lambs and kids
• Toxicities seem to be less in goats (metabolism)

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Mineral Summary

• Cattle sheep supplements work for goats
• Salt (free choice) is necessary
• Phosphorous low in forages
• Calcium low in concentrates
• CaP ratio ideally 1.51 to 21
• High Mg supplement in early lactation
• Cu, Se, Co in trace minerals