| ||Minerals are feed ingredients essential for life. Sheep require minerals in order to grow and to raise lambs, produce milk and wool. Minerals serve many functions within an animal. They are important for bone development, enzyme activation, muscle contractions, regulating acid-base balances and are a component of hormones critical for maintaining the well-being of your sheep. There are seven major or macro minerals, which are required in relatively large amounts sheep. Sodium (Na) and chlorine (Cl) known as salt are two of the macro minerals. Others include calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K) and sulfur (S). Micro or trace minerals are required in very small or “trace” amounts and include manganese (Mn), copper (Cu), zinc (Zn), selenium (Se), iron (Fe), cobalt (Co), iodine (I) and fluorine (Fl).
Sheep require minerals, including salt, on a daily basis. Failure to supply adequate amounts of minerals in the diet results in poor fertility, weak lambs at birth, reduced milk production, depressed immunity and numerous metabolic disorders. The quantity of minerals required by sheep depends on their age, body weight, stage and level of production and factors like ill health or parasite load. The more productive your sheep i.e. dairy sheep and prolific breeds, the higher their requirements will be.
The level of other minerals in the diet also affects mineral requirements. Too little or too much of one mineral can render another one deficient or toxic. For example, forages grown on soils containing excess molybdenum (Mo) may be high in Mo and can induce Cu deficiencies in sheep consuming adequate levels of Cu. The recommended intake of Cu for sheep fed diets containing more than 3.0 ppm of Mo is 19-23 and 14-17 ppm for for gestating and lactating ewes respectively and 17-21 ppm for growing animals. Adding minerals is a critical part of providing a nutritionally balanced diet for your flock. However, determining which mineral mix to use can be difficult. For that reason it is recommended that feeds be tested and rations be balanced to meet the flock needs. SheepBytes ration balancer is a tool to manage flock nutrition and is available to sheep producers, nutritionists and veterinarians.
Expressing mineral levels
Mineral requirements are generally expressed in grams or as a percentage of the diet.
A gram is a very small amount of feed and is equal to 1/1000 of a kilogram or 1/28 of an ounce (28 grams = 1 ounce). Mineral concentrations on your feed tags or mineral bags are usually expressed in parts per million (ppm).
One ppm is equal to1 milligram per kilogram (mg/kg) or .0001%. Vitamins included in mineral mixes are expressed in international units (IU).
Referring to a mineral mix
Mineral mixes are referred to by their concentrations of Ca and P. For example, an 18:18 mineral contains 18% Ca and 18% P while an 18:9 mineral contains 18% Ca and 9% P.
Choosing a mineral mix
There are a variety of salt and mineral mixes commercially available that are specifically formulated for sheep. These mixes range from trace mineralized salt to salt-free minerals to mineral mixes that contain vitamins. When you feed a complete trace mineral mix containing salt, no other source of salt should be available to your sheep. The sheep will eat the complete mineral mix to get the salt. Some commercial mineral mixes also contain vitamins A, D and E. If you buy a mineral mix with added vitamins, choose the one containing the highest level of vitamin A (up to 500,000 IU). In some vitamin-mineral mixes the level of vitamins may not be high enough to meet the requirements of your sheep. Talk to a nutritionist to ensure you are supplying your sheep with adequate levels.
Adding specific minerals like Ca is also a way of incorporating minerals into the diet in some circumstances. For example, adding limestone or calcium carbonate is an inexpensive way to supply the Ca required by lambs fed high grain diets or ewes fed green feed or grass hay as roughage.
Minerals can also be supplied in a custom mineral mix that is specifically designed to meet the mineral requirements of your sheep based on an analysis of your homegrown feeds. When the nutrient content of your homegrown feeds changes, so must the minerals supplied in your custom mineral mix. A custom mix for one region may not supply adequate amounts of minerals in another region. Soil type, plant species and growing conditions affect mineral levels in plants.
Determining the best buy
Phosphorus is an expensive mineral to buy so you should always compare different mineral mixes based on the cost of P. For example, if you have the choice between an 18:18 mineral that costs $20.00/25 kg bag or an 18:9 mineral that costs $16.00/25 kg bag you need to determine which mineral is the more economical choice. The calculations below will show you how to do this.
|1.|| Determine the amount of P in each bag of mineral by multiplying the percent P in the mineral by the number of kg in the bag. The 25 kg bag of 18:18 mineral has 4.5 kg P (18/100 x 25 = 4.5) and the 25 kg bag of 18:9 mineral has 2.25 kg P (9/100 x 25 = 2.25).|
To calculate the cost of each kg of P you divide the cost of the bag of mineral by the number of kg of P in the bag. The cost of the 18:18 mineral is $20/ 25 kg bag. Therefore the cost per kg of P is $4.44 ($20.00 ÷ 4.5 kg = $4.44). The cost of the 18:9 Mineral is $16/25 kg bag. The cost per kg of P is $7.11 ($16.00 ÷ 2.25 = $7.11)
From the calculations, you can see that the more expensive bag of 18:18 mineral is a much cheaper source of P and would be the better buy. Sheepbytes ration balancer can also be used to determine the cost of different minerals in flock rations.
Copper and sheep
Mineral mixes or trace mineral salt formulated for cattle or horses should not be fed to your sheep because they are too high in Cu. Sheep minerals contain 300 to 500 mg/kg of Cu. Sheep accumulate Cu in the liver more easily than other livestock species. The accumulation of Cu in the body can take several months and may be caused by feed mixing errors, or by feeding forages, processed feeds or trace mineralized salt high in Cu. If your sheep mineral contains Cu don’t feed a trace-mineralized salt containing Cu. Excessive intakes of Cu can also be caused by feeding by-product feeds consisting of wastes from other livestock species, such as poultry litter. Copper poisoning also may result from low intakes of Mo, S, Zn and Ca. Stressful situations such as handling, strenuous exercise, transporting, a declining nutritional state and weather can cause a sudden release of the stored Cu into the blood, and cause toxicity. Symptoms of Cu toxicity occur quickly and include poor appetite, excessive thirst, pale yellow membranes (jaundice), anemia and death. There appears to be some breed differences in susceptibility to Cu toxicity, with Texels being more susceptible than other breeds.
Once you have determined which minerals you are going to use you need to determine how you are going to feed them to your sheep. Although minerals can be fed free-choice it is recommended that they be mixed with the ration to ensure that all of your sheep consume adequate minerals. However, if you are feeding your minerals free-choice then mix the salt-free mineral with loose salt on a 3 parts salt-free mineral to 1 part loose salt. Most animals, including sheep, have a definite appetite for salt so that minerals that contain salt, particularly loose salt, are usually consumed to a greater extent than salt-free minerals.
Placing your mineral feeders in areas where they are easily accessible to your sheep and are protected from the weather, and winds also encourages intake. Check your mineral feeders regularly to ensure the mineral is fresh, clean and not contaminated with manure. A mature ewe will eat 150 to 225 gm (1/3 to ½ lb.) of a salt-vitamin-mineral mix each week. Regardless of the mineral mix that you use, put out fresh mineral on a weekly basis and monitor your flock’s intake.
- Feed only salt and mineral mixes specifically made for sheep. Sheep minerals contain between 300 to 500 mg/kg of copper.
- Feed a salt mineral mix that contains selenium on a year round basis.
- Feed salt in the loose form to allow for better intake.
- Place mineral feeders where they are easily cleaned and accessible to all of your sheep.
- Protect salt and minerals from the elements.
- Mix salt-free minerals with loose salt on a ratio of 1 part salt to 3 parts mineral to increase intake when feeding free choice.
- Provide no other sources of salt to your sheep when you feed a complete trace mineral mix containing salt.
For more information:
"Sheep & Goat Management in Alberta - Nutrition Module"
"SheepBytes ration balancer" http://www.sheepbytes.ca
Sheep Nutrition Questions? Contact Alberta Ag-Info Centre at 310-FARM (3276)