ROLE OF MINERALS IN LIVESTOCK PRODUCTION
Minerals are inorganic substances that develop the mineral component of the body. Minerals are essential for the correct growth and the functioning of the body and are split into two different groups that are established on the amounts required by the animals body (Sandie. Agar, 2001). Usually the natural occurring mineral elements are located in the animal’s tissues and many are believed to be part of the animal’s food and might not have an essential function in the animal’s metabolism. If the mineral is not essential it is because it is only needed in the diet by a minute amount although it is still very important to prevent deficiencies (P. Wilson, et al, 2005). If there is too much of one micronutrient this excess amount will be passed to the kidneys by the blood for removal as urine and a small amount in sweat.
The different categories of minerals are:–
Macro (Major) minerals are required in greater amounts as they usually include; calcium, phosphorus, electrolytes, magnesium and is involved in nerve functions. For example; horses sweat and lose a lot of body salts therefore, after uncontrolled work they are given electrolytes typically in water (e.g. sodium, potassium, sulphur and chloride). Macro minerals maintain structural integrity, acid-base balance, transmembrane activity- the typical cellular function, muscle contraction and nerve conduction (Sandie Agar, 2001).
Micro (Trace) minerals are only needed in small quantities- per million, some of these are; chromium, fluoride (toothpaste), iodine, magnesium, selenium, zinc, cobalt, and copper which could be the route of all evil because if ingested in excessive amounts it could lead to copper poisoning and pigs commonly suffer from this if they have too much in their diets (BSAVA, 2011).
Minerals are required in small amounts but are important components of the ration. They are essential for cows to remain healthy and for the body to function properly, for the development and maintenance of strong bones and for successful reproduction and production of milk and eggs.
Minerals are chemical elements which form important component of animal feed ingredients. They are essential in ensuring normal and proper functions of the body as well as in maintenance of good health. When an element classified as essential lacks in the diet, animals will in shorter or longer time show deficiency symptoms, which are eradicated or prevented by inclusion of this particular element in the diet. Some elements are required in relatively large amounts compared to others. For this reasons the minerals have been classified as ‘macro-minerals’ (required in larger amounts: grams per kg feed) and ‘micro-minerals’ or ‘trace-minerals’ (required in minute amounts; milligrams or micrograms per kg of feed).
Of the 20 elements that function in animal nutrition, carbon, hydrogen, oxygen and nitrogen are regarded as the non-mineral elements. The other 16 are referred to as the mineral elements which function in animal nutrition. Of these 7 are macro-minerals (required in fairly large amounts) and 9 are micro-minerals (required in very small or trace amounts). Micro-minerals are also sometimes called trace-minerals.
Different livestock types have different mineral requirements, which as far as possible will be described under each livestock type.
Some minerals can be stored in the animal body (liver: copper, bones: calcium) and sign of deficiencies are shown after a longer period of deficient feeding. Minerals that are not stored in the body show signs of deficiency more rapid.
The macro-minerals are: are: Calcium (Ca), Phosphorus (P), Potassium (K), Sodium (Na), Sulphur (S), Chlorine (Cl), Magnesium (Mg).
The micro- or trace minerals are: Iron (Fe), Iodine (I), Copper (Cu), Cobalt (Co), Fluorine (F), Manganese (Mn), Zinc (Zn), Molybdenum (Mo), Selenium (Se).
Macro-minerals
Animals require more of the macro-minerals (Calcium, Phosphorus, Magnesium, Sodium, Potassium, Chlorine, Sulphur) than the micro-minerals (Iodine, Iron, Cobalt, Copper, Manganese, Molybdenum, Zinc, Selenium). If animals do not consume enough of the macro-minerals, this will cause reduced production, infertility problems, weakness of the bone and increased incidences of non-infectious diseases. In cows insufficient Calcium supply causes milk fever. Deficiencies in micro-minerals (trace elements) can cause a variety of diseases and conditions depending on which mineral is deficient.
Calcium and Phosphorus are of particular importance when formulating rations. Legumes tend to have more Calcium and Phosphorus than grasses. Grains are low in Calcium. Young dark green forage tends to have more minerals than old, dry and yellow forages. Most tropical forages are low in Phosphorus.
Extra Calcium and Phosphorus usually need to be provided in the ration over and above that naturally present in the feed and mineral mix, especially for high yielding animals. Tables 2 and 3 show examples of sources of mineral salts (Forages and fodders, agricultural by-products, concentrates and minerals).
• Salt: (Sodium chloride) deficiency develops slow (weeks) but causes unthrifty appearance and low performance. Provision of ad lib salt licks are recommended. Plants tend to be low in both sodium and chlorine. It is therefore an important practice to give common salt to herbivores such as dairy cattle in order to prevent deficiency symptoms. Feeding diets deficient in salt may not show immediate symptoms, but chronic deficiency dairy cattle diets has been shown to lead to low appetite, low milk production and loss of weight. The addition of salt in the diet usually provide immediate cure. Fish meal, Guinea grass, Rhodes grass, Sweet potato vines, Rice and Oat straw and Sugarcane molasses are good sources for sodium.
• Calcium: Calcium is the most abundant mineral in the animal body. It is the most important constituent of the skeleton (bones) and teeth. Calcium also plays important roles in the activities of enzymes and hormones, which catalyse and/or balance the body metabolic processes. Agricultural lime, fish meal, milk, crushed shells, marble dust, some seaweed and green leafy forages, especially legumes, are good sources of calcium. Calcium tend to be low in old, dry and yellowing forages.
In older (multiparous) dairy cows, a condition known as ‘milk fever’ (parturient paresis) commonly occurs shortly after calving caused by lack of available calcium. It is characterized by a lowering of the blood calcium level (hypocalcaemia), muscular spasms, and in extreme cases paralysis and unconsciousness.
Deficiency symptoms: a) rickets in young stock. Joints become enlarged. Bones become soft and deformed. Condition may be corrected in early stages with calcium feeding. b) Osteomalacia or osteoporosis in older animals. Bones become porous and weak. Condition may be corrected by feeding calcium if bones do not break.Examples are known of cows fed too little calcium breaking their backs during mating
• Phosphorus: is needed for bone and teeth formation, building body tissue (growth of animals), milk and egg production. Signs of phosphorous deficiency include animals eating soil, chewing on non feed objects, slow or poor appetite, slow gain of bodyweight, low milk or egg production.Low dietary intakes of phosphorus have also been associated with poor fertility, apparent dysfunction of the ovaries causing inhibition, depression or irregular oestrus.
Sources of Phosphorous: Bone meal, Rock phosphate, Superphosphates such as TSP etc. Also many improved salt licks contain phosphorus. African locust bean, pod pulp, Cotton seed meal, Wheat, bran, Rice bran and Sunflower cake are a good source of Phosphorous, but hays and straws have very low phosphorous content.
• Magnesium: is needed in proper functioning of the nervous system, carbohydrate metabolism and enzyme systems.
Deficiencies: a) Hypermagnesaemia also called grass tetany, grass staggers and wheat poisoning can occur when animals are grazing on young fresh grass or wheat with high protein and potassium content and with very little content of magnesium.
Symptoms are hyper excitability, paralyse and frequent death. Prevention: use animal salts containing magnesium especially when animals are grazing on new young grass or grains such as oats. Banana, stalks, Cassava, foliage, Pawpaw, leaves, Sweet potato vines, Cotton seed meal, soybean and Cocoa pods are good courses of magnesium..
• Sulphur: Sulphur requirements of cattle and sheep are around 0.1-0.2% of ration dry matter. For non-ruminants sulphur should be in the form of sulfur-containing proteins. A deficiency of sulphur will express itself as a protein deficiency, general unthriftiness and poor performance. Good sources of sulphur are Lucerne, Wheat- and Rice bran and Sunflower cake.
Micro-minerals
• Iron: Necessary for blood and some enzyme formation. The precise minimum requirements have not been determined for various classes of livestock, but 80mg of iron per kg of diet is more than adequate for most animals. Deficiencies are most often found in young pigs (other animals much less sensitive): Laboured breathing, flappy wrinkled skin, oedema of head and shoulders, pale eyelids, ears and nose. Prevention/cure: A few drops of ferrous sulphate or similar daily during the first 3-4 weeks. Salt licks containing iron. Cattle fed with roughages iron will be sufficient in general.
• Iodine: Needed for the production of Thyroxin in the thyroid gland. A level of 0.25 mg/kg air dried diet is considered adequate for most classes of livestock. Dairy cows should be provided with 0.5 mg iodine/kg dry matter feed.
Deficiency symptoms: Goiter at birth or soon after, Hairlessness at birth, infected navels, dead or weak at birth. Prevention: mix normal iodized salt (table salt) into the salt licks of the livestock.
• Cobalt: Needed in vitamin synthesis. For cattle and sheep, feed containing from 0.05-0.10 mg of cobalt/kg feed prevents any cobalt deficiency. For pigs cobalt is only needed as part of Vit B12.
• Deficiency symptoms are simply those of malnutrition: poor appetite, unthriftiness, weakness, anaemia, decreased fertility, slow growth and decreased milk and wool production. There are number of disorders due to cobalt deficiency characterized by emaciation (wasting disease or Nakuritis), pining, anaemia and listlessness. Although excess cobalt can be toxic to animals, there is a wide margin of safety level. Thus cobalt toxicity is generally unlikely. Prevention and cure: Where cobalt deficiency is diagnosed, 12.5g of any cobalt salt, such as cobalt chloride, cobalt sulphate or cobalt carbonate can be mixed with 100 kg of normal cattle salt. Barley, grain, Lucerne and Sorghum are relatively high in cobalt.
• Copper: needed for blood and hair production as well as in the enzyme system. Where diets are not high in Molybdenum and/or sulphate the following levels of copper per kilo of diet dry matter have been found adequate:
o Dairy cattle: 10 mg/kg
o Beef cattle and sheep: 4-5 mg/kg
o Pigs: 6 mg/kg
o Horses: 5-8 mg/kg
• High levels of Molybdenum and/or sulphate create unusable salts and may increase the copper requirements 2-3 times. Many areas in Kenya have copper deficiency in the soils and produce feed deficient in copper. Deficiency symptoms are not specific and may include any of the following: Bleaching of hair in cattle especially around the eyes, abnormal wool growth in sheep, muscular incoordination, weakness at birth, anaemia, severe diarrhoea. Prevention and cure: Supplementation of livestock with copper in copper deficient areas is essential. This can be done by using trace mineralized salt containing from 0.25-0.50% copper sulphate. Pigs may be fed up to maximum 250 g copper/kg dry feed. More than 100 mg copper per kilo dry matter may be toxic to cattle and over 50 mg/kg will be toxic for sheep. It is also possible to repair your grazing areas for especially ruminants by upgrading the soil content of copper according to soil analysis recommendations. Generally grass and fodder deficient in copper have yellow or burnt leaf tips and low rates of production. Soybean, aerial parts, Cocoa pods and hulls, Cassava, foliage silage, Cowpea, aerial parts, Sunflower, cake, Maize Stover, Coffee hulls Cotton seed meal, Barley straw and Wheat bran can be sources of copper.
• Fluorine: necessary for healthy teeth, but excess may weaken and stain the teeth. In India fluorine deficiencies are not common, but drinking water especially from boreholes often contain very high levels of fluorine. If the levels of fluorine are too high water can be filtered through a filter containing burnt bones, which will absorb most of the fluorine. This is more practical for human water consumption than for livestock.
• Manganese: influences oestrus, ovulation, foetal development, udder development, milk production, growth and skeletal development. Requirements:
o Dairy cattle: 40 mg/kg of dry matter feed
o Beef cattle and sheep: 5-20 mg per kg dry matter feed
o Pigs: 10-20 mg/kg dry matter feed.
• Deficiency symptoms noted from areas deficient in soil manganese include: delayed oestrus, reduced ovulation, abortions, resorptions, deformed young, “knuckle over” in calves, poor growth. Supplementation is easily done with trace mineralized salts containing 0.25% manganese. Rice products, Guinea grass, , Sweet potato vines, Sorghum straw, Wheat bran, Rhodes grass, Napier grass van be rich in manganese.
• Molybdenum: Important in poultry as it stimulates uric acid formation, and in ruminants stimulates action of rumen organisms. Molybdenum deficiencies have only been observed in poultry in special cases. Molybdenum supplementation is normally not recommended in livestock production. High amounts limit copper availability. Soybean cake, Rice bran, Lucerne, Wheat bran and Sunflower cake can be high in molybdenum.
• Selenium: works in vitamin E absorption and utilization.
Requirements: about 0.1 mg or less per kg dry feed. Deficiency symptoms include: Nutritional muscular dystrophy in lambs and calves, retained placenta in cows, heart failure, paralysis, poor growth, low fertility, liver necrosis, pancreatic fibrosis in chicks. Many areas in India are known to have selenium deficiency of the soils. If selenium deficiency is expected, a soil or feed sample can be sent to any of the major laboratories for analysis. Supplementation must be done very carefully as selenium in too large quantities is poisonous and causes the same problems as selenium deficiency. 1 gram Selenium in the form of sodium selenite can be added to 10 kg dry feed in deficient areas (=10g or 2 teaspoons per 100 kg feed- really not much). Fish meal, Wheat bran, Sorghum grain, Sunflower cake, Lucerne, Wheat grain, Soybean hulls and Rice bran are good sources of selenium.
• Zinc: promotes growth and thriftiness. Promotes wound healing, related to hair and hoofs/claws and wool growth. Deficiencies mostly found in pigs fed on concrete floors. Deficiency symptoms include: general unthriftiness, poor growth, unhealthy looking hair, skin and wool, slow wound healing. Pigs can be supplemented with 50 mg of zinc per kg of dry feed or as trace mineralized salt. Good sources of zinc can be: Soybean, aerial parts, Sugarcane forage, Sunflower heads, Banana, stalks, Neem tree, leaves, Mango leaves, Jackfruit leaves, Maize bran and Fish meal.
A well balanced mineral salt mixture adjusted to local conditions is the easiest way to ensure good mineral balance in animal feeds. It is not common to have feeds analysed for minerals and trace-elements because of the high price of analysing. Free ranging livestock do get reasonable adequate quantities from nature or from sites with natural minerals licks. Commercial mineral mixtures are available and are highly recommended for high yielding cows and intensively raised chickens and pigs
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
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