By Dr. Gene P. Gengelbach, Ph.D., P.A.S.
Given the high cost of feed and ever-shrinking profit margins in the last few years, some producers are tempted to cut back on mineral and vitamin supplementation. Pound- for-pound these are among the most expensive ingredients in the diet, and sometimes producers can’t easily see their value. Even if you can’t easily see a difference in the bulk tank or on the scales, these nutrients are extremely important for proper health, growth, milk production and reproduction. This is the first in a series of articles covering the importance of vitamins and minerals in livestock diets. This article will cover the trace minerals copper and zinc.
Trace minerals are defined as those minerals that are required in small, or trace amounts, usually measured in parts per million (ppm). How much is 1 part per million? In metric measures, it is one milligram per kilogram of feed. That would be the equivalent of .032 ounces per one ton of feed or 1 kernel of white corn in 500 pounds of yellow corn. However, just because these nutrients are needed in extremely small amounts doesn’t mean that they are not important.
Copper (Cu) has been recognized as an essential nutrient for over eighty years. The main function of copper is as a co-factor which enables enzymes to function properly.
Some of the main functions of copper-dependent enzymes are:
Iron transport and red blood cell formation
- Nerve function
Connective tissue formation - (bone, ligaments, tendons, skin)
- Antioxidant
- Pigmentation of hair, fleece or feathers
Some of the results of copper deficiency are:
- Anemia
- Severe diarrhea
- Rupture of the aorta
- Joint disorders and osteoporosis
- Faded hair coat
- Reduced immune function
- Reduced fertility
- Reduced growth rate
The copper requirement for
a lactating dairy cow is generally regarded to be in the range of 15 to 20 ppm; for most classes of beef cattle the requirement is 10 ppm Cu in the diet. For most monogastrics the requirement is in the 4 to 8 ppm range. The animal’s requirement can vary depending upon the biological availability of the copper source; the chloride and sulfate forms are more available than copper oxide, and copper that is chelated with amino acids or complexed with protein or polysaccharides (“organic” minerals) are generally more available than “inorganic” copper sources. Tribasic copper chloride (TBCC) also appears to have greater availability than other inorganic sources. TBCC and the organic minerals are generally thought to be more available to the ruminant because these minerals do not react with other minerals in the rumen. The presence of antagonists such as molybdenum, iron and sulfur interfere with copper absorption by forming insoluble complexes with copper which makes it unavailable to the animal. High levels of other minerals, such as zinc, can also interfere with copper absorption.
Copper is one of the minerals most likely to become toxic for ruminants if over-supplemented. Sheep are extremely sensitive to copper and can show signs of toxicity at levels of 15 ppm in the diet. That is why Agri-King vitamin/trace mineral premixes (VTM, such as Dairy Premium, Dairy Max, and Beef Multifactors) should NEVER be fed to sheep. Pre-ruminant calves have shown signs of copper toxicity when fed milk replacer containing 115 ppm Cu. Older cattle have shown signs of copper toxicity (increased liver Cu, liver and kidney damage) after receiving rations supplemented with 37.5 ppm Cu for over 2 years. There are some reports that the Jersey breed is more sensitive to high copper levels in the diet, but there are no problems when copper is fed at normal levels of supplementation. Goats have a tolerance for copper similar to that of cattle. The maximum tolerable level of Cu is generally considered to be 40 ppm in cattle diets and 250 ppm for swine and poultry.
Agri-King dairy VTMs (Dairy Premium, Dairy Max, LDH) contain a variety of copper sources (sulfates, proteinates and polysaccharide complexes) to optimize both copper availability and value for our clients. Other products which contain supplemental copper are Hoof King®, Super Micro®, and Super Micro® Plus.
Zinc (Zn) is similar to copper in that it is involved in many enzymes and metabolic processes in the body.
Some of the main functions of zinc and zinc- dependent enzymes are:
- Energy metabolism
- Facilitate CO2 transport in the blood
- Protein digestive enzymes
- Antioxidant
- Vitamin A metabolism
- Stimulates appetite
- Gene expression
Some of the results of zinc deficiency are:
- Loss of appetite/reduced weight gain
Parakeratosis (severe dermatitis resulting in hardening and thickening of the skin) - Abnormal bone/skeletal development
- Lameness/hoof lesions
- Reduced protein digestion/absorption
- Decreased immune function, failure of wounds to heal
- Poor reproductive performance
The Zn requirement for both
ruminants and non-ruminants is generally recognized as being in therangeof30to40ppmofthe diet. In cattle the requirements for optimal growth is around 20 ppm, but reproduction and immune function may be optimized at slightly higher levels. High levels of calcium and phytate (from cereal grains) can interfere with Zn absorption and therefore increase the requirements for zinc in monogastrics. Excessive amounts of iron in the diet can also limit absorption of zinc. Bioavailability of the various inorganic zinc sources are similar, and organic Zn sources are generally considered to result in slightly higher retention of zinc in most cases, especially during periods of stress. There is some evidence that zinc, especially in the organic form, may help improve hoof health and also lower the somatic cell count in dairy cows.
Zinc is relatively nontoxic to most species of farm animals. Early signs of zinc toxicosis are reduced feed intake and growth rate, and creation of a secondary deficiency of copper (high zinc leads to reduced copper uptake and therefore copper deficiency). Dietary levels of 700 ppm Zn can cause toxicity symptoms in pre-ruminant calves. The reported maximum tolerable concentration of Zn in ruminant diets is 500 ppm. The maximum tolerable level for swine and poultry is 1,000 ppm, but recent research indicates that the level for poultry may be lowered to 500 ppm.
Agri-King VTM products also contain a variety of zinc sources (sulfate, polysaccharide complex and proteinates) to optimize bioavailability and value. Hoof King®, Key-Bac Paste®, Super Micro® and Super Micro® Plus also contain supplemental zinc to help maintain feed intake and hoof/tissue integrity, support the immune system and improve reproduction during times of stress. When fed at recommended levels, Agri-King VTM products more than meet the NRC recommendations for both copper and zinc, so you can rest assured that your animals are able to reach their peak performance on the Agri-King feeding program. AK
