Cattle have a small tolerance range for Se, with 0.10 ppm being the requirement and 5 ppm being toxic. Soil composition drives Se content of forages and the arid regions with more Ca in the soil are more likely to have higher selenium levels. In general, west of the Missouri River has adequate Se and some areas have toxic levels, while east of the Missiour River can be deficient. Selenium can be a challenging mineral in South Dakota. Other indicators are poor growth rates, low birth weights and increased abortions. If Mn requirements are not met, the primary indicator will be reduced conception rates. However, Mn interacts with other minerals so deficiency effects could be noticed at lower Mn levels. Cattle have a high tolerance level for Mn, up to 1,000 ppm. The requirement for Mn in growing and finishing cattle is 20 ppm, while the requirement in pregnant and lactating cows is 40 ppm. Manganese plays an important role in growth and reproduction. Another symptom of deficiency is goiter, an enlargement of the thyroid gland. Cows that are deficient in I while they are pregnant can have calves that are born blind, weak, hairless or stillborn. If I levels are low, thyroxin production is reduced and results in lower metabolic rates, that has a snowball effect on decreasing milk production, weaning weights and overall herd health. Iodine plays a key role in maintaining metabolic rate by producing the hormone thyroxin from the thyroid gland. The requirement for I is very low (0.5 ppm), however deficiencies are more prevalent than toxicities in the northern United States. Cattle with a Cu deficiency are characterized as having a lighter colored hair or faded hair coat, reduced conception rates, severe diarrhea, brittle bones and reduced immune response.

In addition, soil type can play a role in Cu availability, with alkaline soils reducing that availability. When this deficiency is coupled with increased levels of the minerals listed above, supplementing adequate levels of Cu becomes more challenging. The forage mineral samples collected over the last three years in the western Dakotas have all been deficient. These include zinc (Zn), iron (Fe), selenium (Se) and phosphorus (P). Multiple minerals besides Mo and S can also interact and decrease Cu availability. There are some areas in western South Dakota that this ratio is reversed and modifications to the mineral supplement program need to be made. The cow’s requirement for Mo is very small and frequently met by forages in grazing cattle. This ratio needs to be between 2:1 and 4:1. The challenge is ensuring that the Cu:Mo ratio is correct and will not cause a negative interaction. Not only does Cu play important roles by itself, but the combination of Cu, S, and Mo creates several important enzymes involved in nucleotide and vitamin metabolism. Copper and MolydenumĬopper plays many important roles in the cow’s system, including red-blood cell health, collagen development, reproduction, and immunity. Vitamin B12 is then used by rumen microbes in metabolic processes to produce propionate, which is a volatile fatty acid that provides energy to the cow. The cow does not readily absorb Co, but the rumen microbes use it for vitamin B12 synthesis. Cobalt deficiency is characterized by depressed appetite, listlessness, decreased growth, reduced milk production and a rough hair coat. The requirement for Co is 0.10 ppm and is typically adequate in summer range and many silages, but can be deficient in low-quality forage (e.g., winter range, crop residue). They each play important roles in the body and can have negative impacts if they are deficient or in excess. These are cobalt (Co), copper (Cu), iodine (I), manganese (Mn), selenium (Se) and zinc (Zn). There are six trace minerals of significant importance in a cow’s diet. This article will discuss trace minerals while a previous article discussed macro minerals. The macro minerals are required as a percent of the diet dry matter, while micro minerals or trace minerals are required in ppm (parts per million). Minerals are divided into two groups based on the quantity of the mineral required by the cow: macro minerals and micro minerals (trace minerals). There is value in analyzing your mineral program to determine if modifications need to be made to improve cattle health and performance. Without appropriate balance of minerals, cows may not perform as desired or could exhibit detrimental effects. Mineral nutrition is vital to overall cow performance. Originally written by Adele Harty, former SDSU Extension Cow/Calf Field Specialist.

Macro minerals and micro minerals