Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS

1 st WorkshopXIII International Feed Technology SymposiumThe absorbed manganese is readily transported by blood to the liver and bones.Manganese is not concentrated in any particular organ or tissue. The concentrations inthe bones, liver, kidneys and pancreas (1-3 mg/kg fresh tissue) are higher than those inthe skeletal muscles (0.1-0.2 mg/kg).The manganese concentration in livestock feed is variable, depending on the fodderplants used, soil pH and soil drainage [17]. Therefore, complete feeds for beef cattlemust be supplemented with adequate forms of manganese, most commonly manganeseoxide and manganese sulfate. If the relative biological availability of manganese frommanganese sulfate is 100%, the availability from manganese oxide and manganesecarbonate is 60-80 % and 25-40%, respectively [16]. As compared to manganese sulfate,the relative availability of manganese from manganese methionine is approximately 120% [12].The manganese requirements of animals depend on the animal species and dietary levelsof calcium and phosphorus –high levels of calcium and phosphorus have been proved toincrease the need for manganese [11, 7, 15]. The evaluation of manganese requirementsis hampered by inadequate research data on manganese availability (manganeseavailability in poultry nutrition is estimated at 5%). The manganese requirement for beefcattle is 20 mg Mn /kg diet.Manganese deficiency in young animals leads to skeletal abnormalities (includingstiffness, twisted legs, swollen joints and reduced bone strength). In older cattle, itcauses poor or irregular oestrus response, low conception rate, abortion, stillbirths andlow birth weight of offspring.No limits are prescribed by the Codex Alimentorum, for iron and manganese.The highest amounts of potassium and sodium in animal tissues are stored in muscles,and those of calcium in the bones. Potassium is the major cation in the intracellular fluidinvolved in the acid-base balance, regulation of osmotic pressure, water balance, smooth,skeletal and heart muscle contractility, nerve impulse transmission and certain enzymaticreactions. The potassium requirement of beef cattle is around 0.6%. Potassium isabsorbed from the rumen, omasum and the intestines and its absorption is very high.Feedstuffs are excellent sources of potassium, containing between 1 and 4% potassium.Cattle diets can be supplemented with potassium as potassium chloride, potassiumbicarbonate, potassium sulfate or potassium carbonate (all forms are readily available).Sodium is the major cation in the extracellular fluid, the function thereof being tomaintain osmotic pressure, control water balance and regulate the acid-base balance.Another important function of sodium is its involvement in muscle contractions, nerveimpulse transmission, and glucose and amino acid transport.The sodium content of feedstuffs shows high variations. Animal-derived productsgenerally contain higher sodium and chlorine amounts than plant-derived products[19].Calcium is the most abundant mineral in the body. As much as 98 % of calciumfunctions as a structural component of bones and teeth and the remaining 2% isdistributed in extracellular fluids and soft tissues where it is involved in vital functions(blood coagulation, membrane permeability, muscle contraction, nerve impulsetransmission, cardiac regulation, secretion of certain hormones and activation andstabilization of some enzymes).The calcium requirements have been calculated by adding the available calcium requiredfor maintenance, growth, pregnancy and lactation and correcting for the percentage of308