Cattle grazing pastures with excessive soil-test phosphorus could also be getting sufficient of the nutrient from the grass to get rid of the necessity for a phosphorus feed additive, in keeping with Arkansas Agricultural Experiment Station analysis.
“Phosphorus is critical for growing heifers,” says Beth Kegley, professor of animal science for the Arkansas Agricultural Experiment Station, the analysis arm of the College of Arkansas System Division of Agriculture. “It is vital for all power wants, metabolism, bone development, fertility and different makes use of.”
In lots of areas of the state, particularly in northwest Arkansas, farms typically have each beef cattle and poultry operations, says Jeremy Powell, professor of animal science and Kegley’s co-investigator.
“There was a rise in phosphorus concentrations in soils the place livestock and poultry manure have been repeatedly utilized to grazing pastures or hay meadows,” Powell says. “Consequently, forages grown on soils excessive in phosphorus are inclined to include excessive quantities of the mineral itself.”
Powell says that phosphorus is an costly ingredient in the price of common mineral supplementation of beef cattle. He and Kegley investigated whether or not it was essential to complement phosphorus in areas the place these concentrations, sometimes called soil-test P, had been excessive.
“The target of this analysis was to look at the results of phosphorus consumption from grazing on beef heifer development efficiency and conception charges,” Kegley says.
The research used two units of 72 crossbred Angus heifers over two years, every distributed into eight teams in keeping with weight about 30 days after weaning. They fed a management group a supplemental mineral combine that had no phosphorus. The others received an an identical weight loss program besides with the addition of 4% supplemental phosphorus within the mineral combine.
All of the heifers grazed blended grass pastures with a historical past of livestock and poultry manure software that resulted in soil-test P ranges of greater than 130 elements per million. The analysis workforce additionally supplemented the animals’ forage weight loss program with 0.5% of their physique weight in soy hulls.
Kegley says they measured the animals’ physique weights all through the research. The researchers collected reproductive tract rating knowledge earlier than the breeding season and being pregnant knowledge following a two-month breeding season.
She says mineral consumption all through the research didn’t differ between the animals that obtained phosphorus dietary supplements and people who didn’t. Additionally, reproductive tract scores, measured by ultrasound twice in the course of the research, didn’t fluctuate considerably between the 2 teams. Being pregnant charges had been comparable for the management group that didn’t obtain supplemental phosphorus at 79% versus 80% for the group that obtained the supplemental phosphorus.
“The outcomes confirmed phosphorus supplementation of growing beef heifers for about 300 days following weaning and all through the breeding season didn’t enhance development or copy when the heifers had been grazing pastures with a historical past of livestock or poultry manure software,” Kegley says.
“For Arkansas, the meat cattle stock was about 800,000 head in 2020,” Powell says. “Theoretically, if substitute heifers had been roughly 20% of the whole cowherd within the state, that may be 160,000 growing heifers.
“The discount of value of the mineral supplementation for this era was about $8.10 per head, probably decreasing the annual value greater than $1.29 million for the event of the Arkansas beef heifer substitute herd.”
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