Grazing areas in the northern beef industry consist of the high rainfall coastal regions and the progressively drier inland areas, both of which periodically experience marginal deficiencies of some microminerals.
Whilst the incidence of clinical symptoms is very low it is recognised that adequate levels of microminerals are necessary for optimal production and animal welfare.
Cattle grazing pastures in the northern beef industry are most likely to have nutritional shortfalls when the pastures are mature, dormant or experiencing drought conditions.
“Stock at most risk are lactating cows and weaners due to their higher nutritional requirements.”
The rate of animal production (liveweight gain and milk production) depends on the nutritional value of the feed and the quantity of food eaten. Studies show that tropical pastures are 13-20 percent lower in digestibility than temperate pastures. Higher levels of indigestible fibre leads to lower total dry matter intake (TDMI) and reduced intakes of total digestible nutrients (TDN) including micro and macro minerals.
Studies have shown that animals grazing pastures and forages with marginal levels of microminerals can experience subclinical signs of deficiencies, that is, reduced reproduction rates, lower levels of production (eg growth and liveweight gains) and greater risk of infectious diseases.
While major nutrient deficiencies (energy and protein) are well defined for cattle, micromineral deficiencies are less well documented for cattle grazing pastures in the northern beef industry.
The intention of this article is to provide an introduction to the function of microminerals, discuss the impact of micromineral deficiencies on animal performance and examine factors that affect the microminerals requirements of beef cattle.
MICROMINERAL REQUIREMENTS
The micromineral requirements of beef cattle are based on the ability of the animal to maintain a desired level of performance. Table 1 shows the micromineral requirements for several categories of stock.
Essential microminerals are necessary for the well-being and the production and reproductive performance of cattle. Microminerals are only required in very small amounts (ppm) to promote normal tissue growth, homeostasis, energy functions, cell regulation and immune function.
“Micromineral deficiencies can be classified as primary and secondary.”
A primary deficiency is caused by inadequate dietary intake of one or more essential minerals, while secondary deficiencies are caused by interference in absorption, distribution and retention of a mineral. Deficiencies can occur simultaneously making the evaluation of mineral status and the calculation of micromineral supplementary programs complex.
Marginal micromineral deficiencies in the tropics and subtropics occurs more frequently than realised which can pose a larger problem than clinical deficiencies because losses to production and performance can go undetected and not rectified.
As with macrominerals, caution is required when providing microminerals since all elements are toxic when fed incorrectly and actual requirements are affected by many interactive factors.
“If not supplied in the correct amounts and ratios, specific metabolic diseases and/or toxicities can occur.”
COBALT (CO)
Cobalt functions are a component of B12 (vitamin) which is synthesised by microbes in the rumen.
Cattle can tolerate approximately 100 times their dietary requirements and Co toxicity is extremely unlikely unless there are major errors in the formulation of the ration. Toxicity signs include decreased feed intake, reduced weight gain, anaemia and weakness.
Young cattle are more sensitive to Co deficiencies than older cattle. Deficiency symptoms are depressed appetite, reduced growth, immune system problems and reduced rumen microorganism production.
Whilst not common in Queensland and Northern NSW, Co deficiencies are generally seasonal and deficiencies can be accentuated when pastures receive high levels of liming and superphosphate fertiliser.
Treatment for animals showing clinical signs of Co deficiency is a vitamin B12 injection which lasts up to 3 months subject to the severity of the deficiency.
Cobalt sulphate and cobalt carbonate are examples of cobalt supplements for beef cattle. For a mineral supplement with an expected 125gms/head/day intake the supplement should contain 10ppm cobalt.
Copper (Cu)
Copper is an essential element required for enzyme systems, iron metabolism, connective tissue, metabolism and mobilisation plus the integrity of the central nervous system and immune systems.
Copper functions in the immune system through energy production, neutrophil activity and antioxidant enzyme production. It also aids the development of antibodies and lymphocyte replication. If the immune system is compromised the stock are more prone to infectious diseases and diarrhoea.
Copper is necessary in the postpartum cow for proper involution of the uterus, displaying oestrus ovulation, conception and maintenance of the new foetus (Table 2).
“Copper deficiency causes reduced reproduction and embryo deaths”
Clinical signs of Cu deficiency include illthrift and poor calf growth and loss of weight in adult animals. The hair coat will be more yellow but some Cu deficient cattle show little change in hair coat colour.
Another sign of Cu deficiency is lameness and incoordination of movement and spontaneous, fractures of bones. Tissue in the heart degenerates and is replaced with fibrous tissue leading to heart failure.
In certain geographical and topography locations (eg coastal areas and low lying poorly drained country) grazing animals are more likely to develop copper deficiency due to the low content and low availability of copper in water-saturated pastures. Copper release from plants depends on the type of forage and stage of vegetative growth. Cattle grazing low quality forages, particularly in late summer and wet winters, are more likely to be copper deficient.
“Molybdenum, sulphur, iron and zinc reduce copper status and can impact on copper deficiency.”
Forage plants may have high molybdenum (Mo) levels from high Mo soils, especially soils that are highly alkaline. Mo can limit the animal’s use of copper, especially if the diet is high in iron and sulphur. High levels of Zn and Fe depress Cu absorption and tend to increase requirements.
If the Mo content of the diet is less than 1ppm of the total dry matter, 8-15ppm (TDMI) of copper in the diet should be adequate. If the Mo content in the diet is greater than 2.5ppm copper may need to be increased by 5ppm if copper levels are marginal.
Copper is more available in concentrates than forages. Forages vary greatly in copper content and may contain variable levels of Mo, S and Fe which reduce Cu levels. Legumes generally have higher levels of copper than grasses. Oilseed meals have higher Cu levels than cereal grains.
Supplementation with selenium (Se) increases copper availability to the anima, but additional care needs to be taken when supplementing Se deficient cattle.
Copper supplements include copper sulphate, copper carbonate and copper oxide. In a mineral supplement fed at 125gms/head/day, 1200ppm copper is recommended.
Copper in excess is extremely toxic particularly with young stock.
ZINC (ZN)
Zinc is a component of many enzymes and is important for immunity systems, reproduction, skin health and plays an important role in protein production. Table 2 summarises the potential effects of Zn deficiency in cattle.
Reports of Zn deficiency are rare and difficult to diagnose since cattle have a limited capacity to store zinc. Signs of deficiency include reduced feed intake and weight gain, excessive salivation, swelling of the feet and legs and lesions around the nose and mouth.
Similar to several other minerals, zinc concentration in forages depends on many factors. Zinc is higher in legumes than grasses and generally high in cereal grains.
Supplemental sources of zinc include Zn oxide, Zn sulphur, Zn methionine and protonate forms. The oxide and sulphate forms have similar bio availabilities.
In a mineral supplement designed to provide under 125g of intake /head/day, 3000ppm of zinc is recommended
Zinc is toxic at very high levels and far higher than the animal’s requirements.
MANGANESE (MN)
Manganese plays an important role in growth and reproduction. Table 3 summarises the main deficiency symptoms which relate closely to reproduction and fertility and Mn is linked to enzyme functions and skeletal growth.
Ironically, Ca and P which are closely linked to bone growth can inhibit Mn absorption when fed in high levels.
Mn requirements (Table 1) vary depending on the stage of production (eg growing cattle need 20ppm whilst pregnant lactating cows need 40ppm).
As with Co, Mn has a fairly safe feeding range with tolerance levels as high as 1000ppm. Mn, however, interacts with many different minerals which can alter the animals tolerance level for Mn and the minerals with which it interacts.
Forage Mn levels vary with plant species, soil pH, soil drainage and forages generally have sufficient Mn.
Supplements include manganese sulphate, manganese oxide, manganese methionine and manganese proteinate with different levels of bioavailability. Manganese methionine and proteinate have the highest levels of bioavailability.
SELENIUM (SE)
Selenium in conjunction with vitamin E boosts the function of immune systems and is important in the development of the antioxidant enzyme system. The symptoms of Se deficiency are shown in Table 3.
“Selenium is very toxic and should only be used carefully in a premixed form”
Signs of chronic selenium toxicity include lameness, anorexia, sore feet, cracked and deformed hooves, liver and kidney inflammation. In severe toxicity cases, difficult breathing, diarrhoea, muscle incoordination, abnormal posture and death from respiratory failure are observed.
Because of the low tolerance range, Se has been a difficult element to supplement although research suggests that Se tolerance is marginally greater than the literature indicates.
Selenium supplements include sodium selenite, sodium selevate, selenomethionine or selenium injections.
A mineral mix fed at 125gms/head/day should not exceed 25ppm selenium.
IODINE (I)
Iodine is an essential mineral for the function of the thyroid hormones. Deficiency symptoms are shown in Table 3 although deficiencies are very rarely seen in the northern beef industry.
Thyiocynate in white clover and glucosinolates in brassicas impair the uptake of iodine. Soyabean and cottonseed meal have also been reported to have goitrogenic effects but with no reported deficiencies when fed to cattle.
Iodine toxicity reduces weight gain, lower feed intake and causes coughing and nasal discharge.
Dietary iodine supplements include calcium iodate, ethylenediamine dehydroidide (EDDI), potassium iodide and sodium iodide. Calcium iodate and EDDI forms are very stable and have high bioavailability in cattle.
Recommended supplementation rate in a mineral mix designed to provide 125gms of intake /head/day is 80ppm of iodine.
IRON (FE)
Iron is primarily required for the formation of hemoglobin and myoglobin, two proteins used in oxygen transport throughout the body. Deficiency symptoms are shown in Table 3, however deficiencies due to low intake are very rarely seen with grazing animals. Conditions that cause blood loss (eg parasite infections and injuries) can lead to iron deficiency.
Iron deficiency causes anemia, lethargy, lowered feed intake, reduced weight gain and pale mucous membranes. Young cattle have higher iron requirements than mature cattle.
Iron toxicity includes diarrhoea, acidosis, hypothermia, reduced feed intake and reduced weight gain.
Excess iron depletes copper levels in cattle and can contribute to copper deficiency if copper supplementation does not compensate for copper losses.
Iron sources include forages, cereal grains, protein meals, water and soil ingestion. Pastures provide variable amounts of Fe and the bioavailability is also variable.
Common Fe supplements include iron sulphate, iron carbonate and iron oxide with varying bioavailability from most to least respectively.
BOTTOM LINE
Microminerals are needed for vitamin syntheses, hormone production, enzyme activity, tissue syntheses, oxygen transport, energy production and other physiological processes related to growth, reproduction and health.
“The requirements for microminerals are based on the levels required for optimal performance”
The main microminerals are copper (Cu), zinc (Zn), manganese (Mn), cobalt (Co), iodine (I), iron (Fe) and selenium (Se).
There are many factors that affect an animals response to microminerals supplementation such as the duration and concentration of mineral supplementation, physiological status, the absence or presence of dietary antagonists, environmental factors and the influence of stress on micromineral metabolism.
Microminerals (trace elements) whilst required in relatively small amounts (less than 100ppm) compared to macrominerals (greater than 100ppm) are equally, if not more important.
It is essential that microminerals are supplied within narrow concentrations in the diet. Acute deficiencies and clinical symptoms are not common but subclinical deficiencies reduce growth, lower reproductive rates, use feed less efficiently and may cause the animal to be more susceptible to infectious diseases due to depressed immunity functions.
“Since many factors can affect responses to microminerals supplementation, feeding programs can be challenging”
Given the complexity of establishing micromineral deficiencies and the need for correct balances, proper ratios and amounts of microminerals it is important to consult with a nutritionist when assessing, designing and implementing micromineral supplementation programs.
FURTHER READING
Health – Immune Systems and Micronutrients for Beef Cattle – Brahman News, March 2017, issue 194
Nutrition – Macrominerals for Beef Cattle – Brahman News, September 2016, issue 192
TABLE 1: GENERALLY ACCEPTED BEEF COW MINERAL REQUIREMENTS AND POTENTIAL MINERAL FORMULATIONS.
| BEEF NRC REQUIREMENTS | SUGGESTED MINERAL COMPOSITION | |||
| MINERAL | PREGNANT DRY COW | LACTATING COW | GENERAL FORMULATION | HIGH MAGNESIUM |
| Macrominerals (%) | ||||
| Calcium | 0.25 | 0.25-0.36 | 10-12 | 12-16 |
| Phosphorus | 0.16 | 0.17-to 0.23 | 6-12 | 2-4 |
| Potassium | 0.60 | 0.70 | – | – |
| Magnesium | 0.12 | 0.20 | 4-5 | 10 |
| Salt | 0.07 | 1.10-0.15 | <15 | 15-25 |
| Sulphur | 0.15 | 0.15 | 2-3 | 0-3 |
| Microminerals (ppm) | 50 | 50 | – | – |
| Iron | 40 | 40 | 4,000 | 4,000 |
| Manganese | 30 | 30 | 3,000 | 3,000 |
| Zinc | 10 | 10 | 1,200-2,000 | 2,000 |
| Copper | 0.5 | 0.5 | 100 | 100 |
| Iodine | 0.1 | 0.1 | 60 | 60 |
| Selenium | 0.1 | 0.1 | 30 | |
| Cobalt | 30 | |||
Note:
(1) Recent research suggests that chromium (Cr) and molybdenum (Mo) are also important microminerals.
(2) Source – NRC 2000. Adapted from NRC Requirements for Beef Cattle.
(3) One part per million (ppm) = 1mg/kg
(4) Microminerals are maintained within a narrow concentration and where elements can be toxic, recommended levels of requirements are justifiabibly low (eg Se).
(5) Disease, stress and illthrift can reduce the function of microminerals.
(6) Macromineral intake is expressed as a percentage of TDMI and micromineral intake as ppm of TDMI.
TABLE 2: SYMPTOMS OF COPPER AND ZINC DEFICIENCIES IN BEEF CATTLE
| MINERAL | COW | BULL |
| Copper (Cu) | Illthrift & liveweight lossDelayed oestrusEmbryonic deathDecreased conceptionDelayed pubertyDecreased ovulationReduced immunity and increased infection | Illthrift & reduced liveweightDecreased libidoDecreased sperm productionDelayed pubertyReduced immunity and increased infection |
| Zinc (Zn) | Increased dystociaAbnormal oestrusReduced immunity and increased diseaseReduced locomotion due to lameness and reduced foot healthAbnormal oestrus | Impaired growthDelayed pubertyDecreased testicle sizeDecreased libidoReduced movement due to lameness and reduced foot healthReduced immunity and increased infection |
TABLE 3: SYMPTOMS OF MN, I, SE AND FE DEFICIENCY IN BEEF CATTLE
| MINERAL | DEFICIENCY SYMPTOM |
| Manganese (Mn) | Impaired reproductive performance (silent heats)Skeletal DeformitiesReduced birth weight |
| Iodine (I) | Weak or stillborn calvesImpaired fertilityRetained placentaIncreased susceptibility to soft tissue infectionFoot problems |
| Selenium (Se) | Reduced disease resistanceRetained placentaWeak or dead calvesChronic diarrhoea |
| Iron (Fe) | Generally affects young animalsPoor feed intake and weight gainDepressed immune system and increased sickness and mortalities |
APPENDIX 1
TABLE 1: SOURCE, EMPIRICAL FORMULAS, MICROMINERAL CONCENTRATIONS AND RELATIVE BIOAVAILABILITIES OF COMMON
INORGANIC MINERAL SOURCES
| SUPPLEMENT | EMPIRICAL FORMULA | MINERAL CONCENTRATION (%) | RELATIVE BIOAVAILABILITY (RV) | MINERAL AVAILABILITY (% OF DM) |
| Cobalt | ||||
| Cobaltous sulphate | CoSO4(H20) | 21 | 100 | 21.00 |
| Cobaltic oxide | Co3O4 | 73 | 20 | 14.60 |
| Cobaltous cargonate | CoCO3 | 47 | 110 | 51.70 |
| Copper | ||||
| Cupric sulphate | CuSO4(H2O)5 | 25 | 100 | 25.00 |
| Copper EDTA | Variable | Variable | 95 | Variable |
| Cupric chloride (tribasic) | Cu2(OH)3Cl | 58 | 115 | 66.70 |
| Cupric oxide | CuO | 75 | 15 | 11.25 |
| Cupric sulphide | CuS | 66 | 25 | 16.50 |
| Cuprous acetate | CuC2O2H3 | 51 | 100 | 51.00 |
| Iron | ||||
| Ferrous sulphate heptahydrate | FeSO4(H2O)7 | 20 | 100 | 20 |
| Ferric citrate | Variable | Variable | 110 | Variable |
| Ferric EDTA | Variable | Variable | 95 | Variable |
| Ferric phytate | Variable | Variable | 45 | Variable |
| Ferrous cargonate | FeCO3 | 38 | 10 | 3.80 |
| Selenium | ||||
| Sodium Selenite | NaSeO3 | 45 | 100 | 45.00 |
| Cobalt selenite | Variable | Variable | 105 | Variable |
| Zinc | ||||
| Zince sulphate | ZnSO4(H2O) | 36 | 100 | 36.00 |
| Zinc carbonate | ZnCO3 | 56 | 60 | 33.60 |
| Zinc oxide | ZnO | 72 | 100 | 72.00 |
APPENDIX 2
TABLE 1: EXAMPLE OF MINERAL MIX FOR LACTATING BEEF COWS
Note
i) Magnesium should be increased to 10% if grass tetany is a concern
ii) Sulphur supplementation if necessary can be provided using sulphate found in other minerals (eg sodium sulphate, calcium sulphate, potassium sulphate, magnesium sulphate).
| MINERAL | 125GMS/HEAD/DAY |
| Macro Calcium (Ca) Phosphorus (P) Sodium (Na) Magnesium (Mg) Sulphur (S) | 10-15% 4-8% 15-20% 1% 0.5% |
| Micro Zinc (Zn) Cobalt (Co) Iodine (I) Selenium (Se) Copper (Cu) | 0.03% (3000ppm) 0.001% (10ppm) 0.008% (80ppm) 0.0025% (25ppm) 0.12% (1200ppm) |
APPENDIX 3
TABLE 2: – MICROMINERAL LEVELS IN VARIOUS FEEDS
| FEED NAME | K | FE | CO | CU | MN | ZN |
| Energy Supplement Wheat Barley Maize Oats Sorghum Molasses | 5.8 6.0 5.0 4.0 3.0 31.7 | 50 60 30 80 50 420 | 0.1 0.1 0.0 0.1 0.3 0.0 | 8.1 9.1 3.6 6.6 10.8 5.0 | 40 18 8 42 17 90 | 42 16 11 30 16 32 |
| Protein Supplement Canola meal Coconut meal Cottonseed meal Safflower meal Sunflower meal | 6.0 6.0 13.0 13.0 10.0 | 200 200 230 600 100 | 0.1 0.1 0.2 2.2 0.3 | 11.0 15.0 20.0 97.4 4.0 | 11.0 15.0 20.0 97.4 4.0 | 40 53 22 44 20 |
| Tropical Grasses Kikuyu early Kikuyu late Paspalum early Paspalum late Seteria early Seteria late Rhodes early Rhodes late | 31.0 12.8 13.8 16.4 27.6 37.6 10.0 13.0 | 48.6 280 54 70 48.6 70 270 280 | – – – – – – – – | 1.8 10.2 5.2 6.5 4.7 6.5 26 26 | 9.5 56 36 30 32.4 74 180 120 | 10.1 38 11.2 9.5 10.1 9.5 56 38 |
| Temperate Grasses Ryegrass early Ryegrass late Oats early Oats late | 20 18 20 16 | 280 200 200 200 | – – – – | 5.2 7.0 9.0 9.0 | 85 90 80 65 | 24 30 63 59 |
| Tropical Legumes Cowpeas early Cowpeas late Dolichos early Dolichos late | 4.5 4.7 1.9 1.9 | 90 90 180 180 | 0.7 0.7 – – | 14.0 14.0 12.0 12.0 | 15 15 20 20 | 35 35 30 30 |
| Temperate Legumes Lucerne early Lucerne late Clover early Clover late | 22 25 26 26 | 250 200 413 413 | 0.1 0.1 0.2 0.2 | 16.0 12.0 10.0 10.0 | 42 35 95 95 | 24 27 17 17 |
| Tropical Forages Sorghum Sudan grass | 14.7 18.7 | 200 190 | 0.3 0.1 | 30 37 | 50 90 | 30 38 |
| Hays Temperate Ryegrass High ME Clover High ME Clover Low ME Lucerne High MELucerne Low ME | 16.0 12.0 24.9 22.0 25.0 | 280 180 164 250 200. | 0.1 0.2 0.2 0.1 0.1 | 4.0 7.6 9.0 11.0 9.0 | 75 35 164 45 30 | 30 29 19 24 25 |
| Hays Tropical Seteria Sorghum Sudan grass | 17 19 15.4 | 210 190 200 | – 0.1 0.1 | 26 30.0 36.8 | 120 90 93 | 38 38 36 |
| Silage Maize Oasts Cl/Ryegrass | 9.8 32.8 24.0 | 260 110 180 | 0.1 – – | 4.0 10.9 7.0 | 48 128 90 | 93 65 28 |
Note: Total mineral intake depends on the digestibility and quality of the feedstuff. Subsequently, lower mineral intakes are experienced with tropical grasses, forages and legumes compared to temperate pastures and energy and protein supplements.
BRAHMAN NEWS MARCH 2018 ISSUE #198 PAGE 66
Contributed by Alex Ashwood
