Greg Moore knows what it's like to manage on the edge. He runs 500 mother cows near Wagon Mound, NM — country generously described as “semi-arid.” Calving is April and May; he maintains a 94% calving rate and works to produce a 500-lb. weaned calf.
Getting that kind of production from pastures that are often dying for a drink is no small feat. It starts with an aggressive mineral program tuned to seasons, rainfall and forage.
“We start our mineral program in November, about the time grass starts getting brown,” he says, adding that he tries to leave half his land ungrazed to promote forage growth. “It's a free-choice mineral, and we control the consumption with a little salt.”
He feeds a high-phosphorus mineral, “about 8% phosphorus,” and a supplement that includes the other macro and microminerals recommended for his area. “We need to be reminded every now and then as to what minerals are required,” Moore says.
Beyond mineral supplementation, a protein supplement is provided “on a visual basis,” he says, based on drought and other weather conditions. Due to a mild winter heading into February, he hasn't needed protein supplement for the season. “The goal is to get a calf produced without any form of protein supplement,” he says, “but if you have a tough winter, you can't do it without adding a supplement.
“If that happens, you keep the supplement going until April or May when the grass greens up. We try to not have to sell any cows because of a drought or dry spells. So we must be flexible.”
Ted McCollum, Texas AgriLife Extension beef cattle specialist in Amarillo, defines macrominerals as those required in grams per day or head. They are required for bone formation and integrity, muscle functions, neural function, protein synthesis and energy metabolism. Macrominerals are calcium, magnesium, phosphorus, potassium, sodium and sulfur.
Microminerals are usually measured in parts per million. They include cobalt, copper, iodine, iron, manganese, selenium and zinc. They're required for vitamin synthesis, hormone production, enzyme activity, tissue synthesis, oxygen transport and other physiological processes.
“A mineral supplement is a management tool just like supplement feed. Failure to provide adequate mineral supplement may not result in clinical deficiency symptoms, but instead, unseen production losses,” McCollum says. These unseen losses may include calf growth at a reduced rate, reproductive losses and increased susceptibility to parasite and disease problems.
Of course, naturally occurring mineral concentrations are greatest when pastures are green. They shrink when grass is dormant. “And contrary to some beliefs, cattle are not able to determine which minerals are lacking,” McCollum says.
“Following periods of deprived mineral consumption, cattle may consume several times the recommended level of supplement. But research shows that phosphorus- and calcium-deficient cattle did not consume enough free-choice dicalcium phosphate to correct the deficiency.”
He advises producers to “let the mineral content of forage and feed and daily requirements determine what and how much mineral to feed — rather than basing the decision on whether the cattle will or won't consume a supplement.”
Like just about everything in cattle production, mineral prices are higher, especially phosphorus and potassium. “The 200-300% price increases of supplements grabbed the attention of producers and feed companies,” McCollum says. But cutting mineral supplementation can hurt cattle performance.
“Don't just put something out based on purchase price only,” he stresses. “Items such as trace-mineral salt aren't the same as complete mineral mixes and are many times inadequate. A complete mineral mix contains salt and concentrated macro and microminerals.”
Also, McCollum says, don't be fooled by low-cost mineral mixes that may include higher levels of salt and less expensive macro and microminerals that are inferior sources and not as effective. “Know what you're paying for,” he says.
A scaled-down program can be used when forage is good. This may involve simply putting out white salt. “During the fall and winter, as forage quality wanes and cattle requirements change due to physiological stage and possible winter stress, move into a ‘full-service’ mineral supplement,” McCollum advises.
“And additional savings may be possible by custom-formulating a range cube that incorporates the mineral package into the protein/energy supplement.”
Seasonal adjustment of mineral supplement, based on mineral concentrations in forage, water and supplemental feed, may be another way to economize. It can be easy to overfeed mineral if all aren't considered, McCollum says.
“Offering protein/energy supplements fortified with mineral in addition to a mineral mix can easily provide some minerals in excess of a cow's requirements,” he says. “Overfeeding is not necessarily detrimental to production, but is a potentially unnecessary cost.”
In gauging methods of reducing the cost of supplemental minerals, the amounts available in range cubes as well as mineral mixes should be considered. Be sure to account for cattle types and characteristics.
“To make these adjustments, one needs to know the nutrient requirements of the particular class of cattle and nutrient content of the feeds and forages,” McCollum says. “Also, the mineral content of water, particularly if it's high in iron or sulfur, should be determined.”
For commercial producers, the year-round use of organic trace-mineral sources generally isn't economically warranted, he adds. “Consider therapeutic use as opposed to routine use,” he adds.
Even in semi-tropical regions, mineral recommendations are similar, says John Arthington, University of Florida beef cattle specialist in Ona.
For example, copper is often deficient in Florida beef cows, which may result in failure to respond to vaccinations and rough, dull hair coats. “Dietary sulfur is an important component in the copper/molybdenum interaction,” he says. “Researchers suspect that dietary sulfur levels greater than 0.35% are highly likely to interfere with both copper and selenium utilization in cattle.”
He adds that blood copper concentrations may be elevated in stressed cattle, suggesting a higher copper requirement. “Consider using copper sulfate, tri-basic copper chloride or an organic source when supplementing copper,” he says. “Copper oxide is poorly utilized in cattle and should not be used in the formulation of their supplements.”
Arthington says signs of zinc deficiency may include compromised hoof integrity, bull reproductive failure and anorexia and weight loss, notably in calves.
Signs of iron deficiency may include anemia, immune suppression and decreased calf weight gain. An iodine deficiency may produce reduced fertility, enlarged thyroid or stillborn, weak and/or hairless calves. Signs of cobalt deficiency include loss of appetite leading to weight loss, listlessness, diarrhea and anemia.
Arthington notes that selenium can be difficult to supplement because it has a narrow range between deficiency and toxicity. “Many regions are concerned with selenium toxicity in pasture forages,” he says. “Selenium is essential for the maintenance of tissue integrity. One widely recognized deficiency symptom is the degeneration of tissue, resulting in a condition referred to as ‘white-muscle disease.’”
Sodium selenite is a commonly used source of supplemental selenium. Because of the selenium-rich pasture forage problem in other regions, selenium inclusion in supplemental feeds is federally regulated at a maximum inclusion level not to exceed 3 mg/d.
Larry Stalcup is a freelance writer based in Amarillo, TX.