MINERALS REQUIRED IN LIVESTOCK DIETS Major minerals (Required in large quantities) Beef Dairy Swine Chicken Finishing Cow Dry Lactating Finishing Sow Broiler Layer Ca, % P, % Mg, % Na, % Cl, % K, % S, % Minor minerals (Required in very small quantities Fe, ppm Cu, ppm Zn, ppm Mn, ppm I, ppm Co, ppm Se, ppm Mo Cr

Minerals are often overfed –Levels of minerals commonly fed in industry to swine Mineral Level fed, % of requirement Ca P Mg Na K Fe Cu Zn Mn –Reasons for overfeeding of minerals High levels in feeds Supplementation to provide safety margin No consideration of mineral bioavailability Free choice feeding of trace mineral salt Use of Cu and Zn salts as growth promotants for swine and poultry Dose, ppm Cu Zn

Utilization rates of most minerals are low Utilization rate Excretion rate (% of intake) Ca P Mg Na K Fe Cu Zn Mn –Factors mineral utilization rates Mineral sources –Organic mineral (Chelates) > SO 4 or CO 3 salts > oxides Level fed –Low levels > high levels Interactions with other minerals –High K reduces Mg absorption –High Zn reduces Cu absorption –Low Cu reduces Fe absorption Processing –Grinding increases mineral absorption Age and nutritional status of animals –Young animals absorb minerals better than adults

All minerals are toxic to animals if fed in excess –Maximum tolerable concentrations Beef Dairy Swine Poultry Sheep Ca, % P, % Mg, % NaCl, % K, % S, % Fe, ppm Cu, ppm Zn, ppm Mn, ppm Mo, ppm I, ppm Co, ppm Se, ppm Cr, ppm –Causes of toxicities Oversupplementation Poor formulation and/or mixing –Wrong feeds fed to wrong species High concentrations in feedstuffs

–Examples High K forages (associated with overfertilization) –Health effects »Milk fever A calcium deficiency occurring to dairy cows in early lactation. Results in tetany and death, if untreated. Caused by overfeeding cations, particularly K, during the dry period. Prevents resorption of Ca from bone. »Grass tetany A Magnesium deficiency occurring to animals grazing lush, heavily fertilized grass pastures in the spring. Results in tetany and death, if untreated. Caused by low Mg content of lush forage and inhibition of Mg absorption by high levels of K and N. High Se forages –Causes »High Se soils in western U.S. »Plant species that accumulate Se –Health effects »Se toxicity Lameness Blind staggers (Labored breathing and ataxia (loss of coordination) –Not yet associated with manure application

In soils, most minerals act like P –Minerals bind to soils high in clay or organic matter Particularly occurs at pH>6 Occurs particularly near soil surface Minerals move to water sources with soil erosion –Minerals do not bind to soils that are high in sand or have a low pH Travel with infiltrating water into ground water sources –Most minerals have limited bioavailability to plants < 40% Results in accumulation of trace minerals in soils –Example: »In areas where swine manure has been heavily applied in North Carolina: soil Zn increased 4 times soil K increased 2 times soil Cu increased 3 times Concern –Once trace minerals have accumulated in the soil, they’re difficult to remove. CONCERNS WITH EXCESS MINERALS IN SOILS

Environmental effects of excessive application of manure minerals Minerals of most concern –P, NaCl, K, Cu, Zn Effects –Toxic to plants NaCl, Cu, Zn, Mn –Detrimental or toxic to animal health –May enter water resources with soil erosion or water infiltration

METHODS TO LIMIT MINERAL EXCRETION IN MANURE Use of precision nutrition of minerals –Limit safety margins when feeding minerals –Utilize mineral sources with high bioavailability Must balance for available minerals rather than total minerals –Balance for individual minerals rather than using complete trace mineral premixes Requires rapid feed analysis –Limit use of free choice trace mineral salt Utilize phase feeding Utilize separate sex feeding Limit feed waste