Writer: D'Lyn Ford
LAS CRUCES - When it comes to feeder design, it's an open and closed case. Cattle will chow down on about 30 percent more of a complete salt and mineral supplement when it's in a simple open feeder compared with a covered vane feeder, a New Mexico State University study found.
"It's simple," said Mark Petersen, a professor of range nutrition with NMSU's Agricultural Experiment Station. "They eat more out of an open feeder than a closed feeder."
Cattle in general don't like to stick their heads into an enclosed area, Petersen said, pointing to one of the closed feeders, which feature a top-mounted weather vane attached to an enclosed, rotating shelter to block the wind. Because they fear predators, cattle spend as little time as possible under the hood, taking a quick lick and pulling their heads out to keep a close eye on their surroundings. A cover also limits the number of cattle that can feed on the mineral supplement at the same time.
The feeder comparison is part of a series of long-range studies underway at NMSU's 29,000-acre Corona Range and Livestock Research Center, 180 miles northeast of Las Cruces.
Mineral supplements are an important part of modern livestock grazing strategy, since
they provide salt, phosphorus and other nutrients needed for most efficient growth, said Tom
Dean, a graduate student in NMSU's animal and range science department who led the study's two years of field work at Corona. Dean examined 150 cross-bred steers in a multifaceted review of mineral supplements and grazing systems using six pastures at the center. Forage in those pastures was deficient in several minerals, including phosphorus, sodium, copper, manganese and zinc. The mix was 46 percent salt and eight percent phosphorous with other minerals added to meet requirements.
Another interesting finding from the stocker cattle study was that relatively little of the mineral mix in the open or closed feeders is lost to weather or wildlife. "Basically, a producer ends up needing to buy one extra sack of supplement a year if he's going to use an open tub," Dean said. The feeders, typically made of black plastic, hold about 50 pounds.
Dean said covered vane feeders do have a place in some settings because they keep out water. One of the drawbacks with the open feeder is that if there's any moisture in the area, the mineral mix will solidify and cattle consumption dips.
"If a producer has a system where he doesn't check the mineral very often, then it may be more beneficial for him to use covered vane feeders to keep the mineral dry," said Dean, a Carlsbad native who previously served as a county agent with the Texas Agricultural Extension Service.
The NMSU study also examined the effects of a zinc sulfate supplement on the animals' average daily weight gain. Dean found that adding zinc to the supplement provided more than the recommended daily allowance, but failed to improve average daily gain.
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