Milk Composition Minerals & Vitamins Leo Timms Iowa State University

Composition of Milk Water, CHO (lactose), fat, protein, MINERALS –Milk contains most minerals found and needed in the body! VITAMINS –Milk contains all vitamins found and needed in the body! It really is the most perfect food!

Minerals Role in the body: –Metabolism –Bone formation and growth –Oxygen transport –Water balance and maintenance –Immune system –Antioxidants Mineral interactions Toxicity vs. Deficiency

Minerals Functions in the mammary gland: –Maintain pH Ionic strength Osmotic pressure –Contribute to buffering capacity

MINERALS 20 MINERALS ESSENTIAL TO HUMANS? MACRO MICRO

Constituentmg/100ml milk Calcium (Ca)123 Phosphorous (P)95 Magnesium (Mg)12 Potassium (K)141 Sodium (Na)58 Chlorine (Cl)119 Sulfur (S)30 Citric acid160

Cow (Paul & Southgate 1978) Human (DHSS, 1977) Sow (Elliot et al. 1971: Bowland, 1966) Sodium Potassium Calcium Magnesium12330 Chloride Phosphorus Calcium/ Phosphorus

Milk MACROminerals Sodium Potassium Chloride Calcium Magnesium Phosphorus Independent of dietary intake!!! Colostrum: higher in everything but K 3 days in milk: normal but K high Little variation across lactation

Sodium, Potassium, Chloride Normal milk: –higher in [K] –lower in [Na] compared to blood plasma Membrane Na-K pump eliminates Na and concentrates K –Na, K, Cl follow the concentration gradient into the vacuole or alveolar lumen –Cl is actively pumped by a membrane pump into the cell against a gradient –Na: primary regulator of extracellular fluids Na / K / Cl: free ions in milk- totally absorbed –concern for human neonate – renal

Calcium and Phosphorus Required in large quantities for the growing neonate Calcium is found as: –Free calcium –Casein-bound calcium (majority; up to 90%) –Calcium--inorganic anions Ca / P / Mg : 40-90% assoc. w/ casein micelle –highly absorbed due to casein / lactose inter.

Calcium transport Little movement from milk to blood –Cannot pass through tight junctions Golgi –Bulk of uptake Calcium pumps –Up and down regulated depending on stage of lactation Can you change Ca content of milk through diet? (Extra credit #3!!!!!)

Milk MICROminerals Trace minerals enter the milk by –Diet –Contamination Metal containers Environment Many are co-factors for enzymes

Iron Low in milk Bound to: –Lactoferrin (humans – better absorption) Protein Anti-microbial –Some caseins *** no correlation with intake!!!!!!!!!

Copper Bound to: –Caseins –β-lactoglobulin –Lactoferrin –Milk fat membrane proteins

Zinc Bound to: –Casein –Lactoferrin –Formation and maintenance of keratin in teat canal Sulfur Transported into cell as part of AA Met, Cys Milk protein

Molybdenum Bound to: –Xanthine oxidase Cell membrane Inner surface of milk fat globule membrane

Manganese – 67% casein bound –Milk fat membrane proteins Cobalt –Vitamin B-12 –Incorporated into protein in RER –High in colostrum –Propionate  Glucose

Iodine Organic Iodine –Chelated –EDDI Iodine dips/foot rot treatment Mammary tissue sequesters iodine –Iodine totally available Legal limits –Toxicity Decreases immune function Cause of acne??

Vitamins Vita – Latin word for “life” Amine – compound containing nitrogen Roles in the body include: –Metabolism –Oxygen transport –Antioxidants –Immune system –Help the body use CHOs Protein Fat Milk contains all vitamins required by mammals

Mastitis Infection of mammary gland Clinical mastitis: visible signs Subclinical mastitis: elevated SCC What do vitamins have to do with it? 53,000 IU/d vitamin A; 173,000 IU/d, 53,000 IU/d mg beta-carotene Less new mammary gland infections (clinical mastitis)

Fat-soluble Vitamins Includes Vitamins: –A –D –E –K Associated with the milk fat globule

Vitamin A Yellow color of milk fat is from ß-carotene Lower efficiency of conversion Some countries fortify with vitamin A Species differences –Cows, humans, and mares contain both Vit. A. & b-carotene –Goat, ewe, buffalo, and sows milk contains Vit. A only

Vitamin D Antirachitic activity Levels related to ergosterol in feed/sunlight –Feeds drop in ½ during winter –Summer milk higher Higher in Guernseys, Jerseys, colostrum Ca absorption from the intestine Milk is often vitamin D fortified in US

Vitamin E and Vitamin K Vitamin E : tocopherol –Antioxidant, protects lipids in milk fat –Related to diet (summer pasture > winter feed) –Highest in colostrum –Low levels in milk –Associated with selenium Vitamin K : –Very low levels in milk

HOW MANY B VITAMINS ARE THERE?

Water-soluble Vitamins - found in the aqueous phase B-Vitamins –Thiamin, riboflavin, folate, B 12, etc. All are found in milk Influenced by diet & breed and species –Change to pasture –Guernsey/Jersey higher than Holstein –Colostrum higher than normal milk Synthesized by rumen microflora and large intestine Many are enzymatic co-factors Extremely important in nutrient metabolism!

Vitamin C Synthesized by ruminants Two forms – Ascorbic acid – Dehydroascorbic acid Colostrum higher than normal milk Much is destroyed during milk processing

Other normal constituents in milk: Hormones –Levels follow trends of blood levels –Changes with estrous cycle, pregnancy, etc. –Usually lower than blood Oligosaccharides –Breakdown products of glycosylated proteins Cell Metabolites –Gases, alcohols, aldehydes, ketones, carboxylic acids, nonprotein nitrogen, sulfur-containing compounds, phosphate esters, nucleotides and nucleic acids Epithelial cells –Sloughed off from duct linings

Abnormal constituents in milk: Toxins –Plants, metals (lead, arsenic, etc.) Viruses Pesticides and Herbicides Radionuclides Bacterial Organisms –Johnnes, Mycoplasma, Salmonella Drugs –Antibiotics Off-flavors –Weeds, poor barn ventilation, ketosis, etc. Oxidized flavors –Exposure to Cu and Fe Exposure to light –Causes lipid oxidation, rancid flavors