By Garth Ruff
The grass is getting greener by the day and the grazing season is within sight. In previous editions of this column my colleagues have covered a variety of topics to consider before turning livestock out to pasture this spring. While checking fences, watering systems, pasture fertility, and forage establishment are often on our minds before spring turnout, another thing we need to consider is our mineral program.
Having a sound, balanced mineral program in place is important throughout the year as minerals are involved in most if not all metabolic functions of our livestock, including growth, reproduction, and lactation. However, it is often on pasture where we run into mineral imbalances and issues. While some issues are harder to detect such as reduced daily gain or lost milk production, others like Grass Tetany are more obvious, and they all can have severe impacts on herd/flock profitability.
Minerals are complex, yet important
There isn’t always a silver bullet for balancing mineral requirements for livestock in pasture. Soil type, pH, and fertility all have an influence are mineral availability to the forage, and thus the mineral intake of the livestock. Furthermore, due to their chemistry (and the periodic table) minerals interact with each other, and these interactions can cause deficiencies or toxicities within the animal.
Here in Ohio we know that many of our pasture soils are deficient in selenium and/or magnesium. Selenium is an important mineral for developing muscle, and often times can be supplemented via injection to young calves and lambs.
Magnesium is a bit more complicated. Grass Tetany is the clinical symptom of a magnesium deficiency. Lush, fast growing forages are often magnesium deficient, especially in fields with high soil test potassium levels. As we look to utilize the rapid forage growth this spring, this is a good time to order and feed a Hi-Magnesium mineral blend.
Copper is also important. Dr. Steve Boyles’ recommendation is to feed a mineral to beef cattle with at least 1000 ppm. Keep in mind copper is also toxic to sheep at high levels.
Not all mineral mixes are equal
In the long run “cheap” mineral mixes aren’t that cheap.
Have you ever blamed the bull for your cows not getting bred? Perhaps fertility was compromised by the lack of mineral bioavailability to the cow. Cheap minerals may contain adequate levels of required nutrients but if they are in a form that is not nutritionally available, what good are they?
If comparing bioavailability of mineral complexes: Organic > Sulfate = Chloride > Carbonate = Oxide. Magnesium oxide is the only mineral in the oxide form that is bioavailable. One might shy away from mineral mixes with other minerals in the oxide form.
As bioavailability increases so does the cost of the mineral mix in the bag. Cheap red trace mineral blocks are red because the predominate mineral in them is Iron Oxide, which is the scientific name for rust, which livestock have no requirement for.
A successful pasture mineral program is only good if managed. We need to know expected mineral intake. Calculate the number of head, counting youngstock, too. Often producers complain about over consumption of mineral and do not account for the calf/lamb getting its share too. We want to have adequate access and consumption.
Mineral requirements change with the animal’s stage of production and environmental situations that reduce feed intake. If mineral intake is too high move the mineral feeder farther away from the water source and loafing areas.
Some producers ‘cut’ their mineral when they think animals are eating too much. Adding salt makes adequate mineral intake tougher to achieve.Source : osu.edu
For example, if a mineral with a recommended feeding rate of 3.0 ounces per day is mixed in a 50:50 ratio with plain white salt, animals need to consume 6 ounces per day to supply the targeted amount of 3.0 ounces of mineral.
What are the costs?
Many free-choice mineral mixes are formulated for 2-4 ounce daily consumption rates. On the high end, if cow consumes 4 ounces of a supplement per day for 365 days, then she consumes 91.2 pounds of the supplement in a year ((4 oz x 365 days) ÷ 16 oz/lb).
Many mineral and vitamin supplements are packaged in 50-pound bags, so a cow mineral bag with a 4 oz/d intake contains 200 animal days worth of mineral ((50 lb x 16 oz/lb) ÷ 4 oz/d).
If your mineral is $35 per bag, that’s $0.175 per day. This is cheap compared to the lost productivity lost (fertility) of a poor mineral program! Happy Grazing.