One of the challenges facing many smallholder dairy farmers is the failure to satisfy the mineral requirement of their animals. Some producers have relied on natural licks known by local names as mwonyo in Eastern Kenya or kuoyo in Nyanza as sources of minerals for their animals. Natural lick is cheap being sold at about Ksh 40 a gorogoro (2 kg container) in many parts of the country. Farmers believe that the natural licks improve digestion, provide essential minerals to animals, increases milk production and have medicinal value to animals.
Usually, these reasons may or may not be valid but there are far more efficient ways of improving animal health and performance than by providing natural licks. More importantly, the question the farmer should ordinarily ask is which are the correct minerals that should be given to livestock under certain conditions?
Minerals form a tiny percentage of dry matter intake in livestock and this may be the reason farmers often ignore it in their herd’s nutritional program. As a farmer, you should know that livestock require about 15 important mineral elements. Seven of these are regarded as major essential elements (macro-minerals) because they are required in relatively larger amounts. These are calcium, phosphorus, potassium, sodium, chlorine, sulfur and magnesium. Minor elements (micro-minerals) are required in trace amounts and include iron, iodine, copper, manganese, zinc, cobalt, selenium and chromium. Although these minerals are essential, they are only required in very small quantities. Normally pastures and feeds contain minerals in sufficient amounts to supply the needs of most ruminants. However, specific mineral requirement depend on the age, weight, stage of production, stress and lactation status of the animal among other factors. Also, pasture conditions determine mineral quantities and availability. For example, during drought, calcium and sodium deficiencies are very common. Also calcium and sodium deficiencies occur in diets based on cereal grains.
Potassium amounts in Kenyan forages are quite high and are adequate in meeting the requirements of grazing livestock. Iron concentrations are likewise high because of large quantities in the soil and animals, through direct ingestion of soil or from soil-contaminated herbage supplement their iron supplies thereby averting deficiency. Except for some parts in Central and Rift Valley regions which are deficient, calcium levels in Kenyan pastures are mostly adequate. Major minerals elements that are likely to limit livestock production in Kenya are phosphorous, sodium, copper, cobalt and minor minerals include selenium and zinc.
Deficiencies in phosphorus are common on red soils. Pasture levels of phosphorous are sufficient to maintain slow maturing and low producing indigenous animals but is inadequate for high producing improved breeds. Low levels of phosphorous in pastures and fodder has causes loss of appetite hence reduced feed intake, retarded growth, interference with regularity of heat hence reproductive rates, lowered milk production and, in extreme cases, depraved appetite or pica.
The concentrations of sodium in pastures throughout Kenya are very low particularly in the dry season. Wet season grass may, however, also contain sodium levels that are insufficient in meeting animal requirements. This is because rapid gain in weight by animals during the wet season induces high mineral requirements. Severe symptoms of sodium deficiency have not been reported in Kenya mainly because most farmers feed salt to their animals.
Copper concentrations in Kenyan pastures are low and a deficiency has been recorded in Rift Valley and parts of Central Kenya. This is especially in soils in which the underlying rock is ash and pumice where copper is usually deficient. Disorders such as stiff gait, rusty coat colour and, in severe cases, fragility of bones in calves have been identified as due to copper deficiency. Copper deficiency is widespread in Kenya and is more pronounced in the dry seasons.
Cobalt is a serious mineral limitation to livestock. It is rare for grasses to contain cobalt in sufficient quantities that meet the demands of grazing animals. Even when grazing is abundant deficiency will lead to chronic starvation or wasting which is often indistinguishable from energy and protein malnutrition. In Kenya, the condition is known as "Nakuruitis" or "Narurasha"i. Cobalt deficiency is common along the Rift Valley and is seasonal in character with symptoms usually appearing after the rains when grazing is plentiful and green. Animals suffering from cobalt deficiency lose appetite and condition, may abort if in calf or may have difficulty to conceive again. The condition affects lactating cows more than any other type of livestock.
Other mineral deficiencies are specific to certain environments and seasonal conditions. They include those of magnesium and selenium. Magnesium deficiency leads to grass tetany, and selenium deficiency leads to white muscle disease. Both conditions require specific treatments.
What is the best method of presentation of minerals to livestock? This is important because some farmers have mixed mineral supplements with feeds or water. Although in some circumstances mixing with feeds is allowed, never mix salt or mineral supplements with water. When you mix with feed or water you will be forcing the animal to take more minerals than it requires and limiting feed or water intake. This is even more serious when you mix salt with water for calves. The calf will tend to drink more water causing haemolysis where it develops respiratory problems, urinates blood and might die eventually.
Salt and mineral supplements are presented in various forms depending on the needs of the animal. The most common are mineral blocks and powders. Mineral blocks and powders however do not provide all the minerals that the animals might need. The mineral profile of natural licks is even lower and their composition varies significantly. You should know from the start that cattle hardly ever get enough minerals if you just give them natural licks.
The most practical solution to phosphorus deficiencies is to provide dry lick or block lick formulated from safe phosphorous sources. In some cases it is far more efficient supplement calcium and sodium by adding lime and salt to the feed ration than to allow free access to licks. When added to the ration, animals will consume the additional minerals they need in proportion to the feed they eat. Selenium deficiency is often treated with ‘bullets’ placed in the rumen, or by specially formulated selenium drenches. However, where mineral supplementation is a routine practice in the farm, the best is to present minerals in form of powder.
Overdosing with minerals such as selenium, zinc, manganese, iodine, copper, molybdenum and cobalt can have toxic effects. This problem is usually avoided by having lower levels of these elements in dry licks or blocks. In this case it is always better to treat animals for the specific deficiency.
Farmers have a wide range of mineral licks to select for their livestock. Majority of farmers however do not know what the particular premix contain and how suitable they are for their livestock. In many of the brands listed below it is not possible to determine the availability of mineral elements available to the animals. Some of these brands cannot support high milk yield hence the farmer should not risk giving to dairy cows.
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