Pasture mineral programs for Beef Cattle

Does your pasture mineral program consist of only blue salt blocks? If so, you could be setting yourself up for a wreck. While cattle do have a need for sodium, iodine and cobalt which are found in blue salt blocks, they contain no other trace minerals. The trace minerals that are of particular concern in Saskatchewan that are not in blue salt blocks are copper, zinc, manganese, and selenium. These trace minerals are essential to maintain animal health, production and reproduction. When not present in sufficient quantities, these trace minerals can cause severe biological problems for the animal and economic losses for the producer.

Copper deficiency in livestock can result from low dietary copper levels, high levels of the mineral molybdenum, high levels of iron and/or high levels of sulphates in drinking water or in the feed. The majority of forages grown in Saskatchewan are deficient in copper. Deficiency symptoms include anemia, loss of color in the hair coat, digestive upset and poor animal performance (growth, lactation and/or reproduction). Young animals and high performance animals are particularly susceptible to copper deficiency. Young calves may express copper deficiency as lameness and/or display bone swellings above the joints. Other symptoms may include an apparent loss or reduction in immunity to parasites (i.e. lice and coccidiosis).

Zinc deficiency in livestock is manifested by reduced growth rate, reduced fertility, para keratosis (thickening and scaling of skin cells), loss of hair, dermatitis (inflammation of the skin), and an increased susceptibility to foot rot and other foot infections.

Manganese deficiency in livestock impairs reproductive performance (delayed cycling, silent heats and reduced conception rates), skeletal deformities and contracted (shortened) tendons in new born calves, enlarged joints and reduced birth weight. Selenium deficiency is most commonly expressed as white muscle disease, but also results in reduced disease resistance, retained placenta and weak or dead calves. Deficiency symptoms are commonly expressed in calves that tend to “lie around”, may lack an aggressive suckling ability, and/or are chronically stiff.

Vitamin E metabolism is similar to selenium and deficiencies can be expressed as having the same symptoms as selenium deficiency.

Mineral supplements are formulated to provide adequate intakes of minerals when fed at the rate recommended by the mineral manufacturer. The feed rate varies depending on the supplement formulation, but is generally in the range of 45 - 70 gm (1.5 - 2.5 oz.) per head/day. Under Saskatchewan conditions, many trace mineral supplements are formulated within the following levels to provide an overall adequate intake of trace minerals.

Copper

2,500-4,000 mg/kg of mineral or fortified salt

Zinc

8,000-12,000 mg/kg of mineral or fortified salt

Manganese

7,500-10,000 mg/kg of min-

eral or fortified salt

Cobalt

40-60 mg/kg of mineral or fortified salt

Iodine

100-200 mg/kg of mineral or fortified salt

Selenium

25-120 mg/kg of mineral or fortified salt