Seeking Solutions in the Sub-Tropics
With about 47 inches of annual rainfall and temperatures that average around 73 degrees annually and rarely drop below 40, much of southern Florida is well suited to cattle ranching. In fact, Florida boasts eight of the top 25-largest cow-calf operations in the country, with most of the largest operations located in the southern 1/3 of the state. One of those operations, routinely among the top-10 largest cow-calf producers in the United States, is the Seminole Tribe of Florida.
The Seminole Tribe governs six reservations in South Florida, with two – Brighton and Big Cypress – suited to agriculture and particularly beef production. The Brighton reservation includes 40 ranches with 14,000 acres of improved pasture and 36,000 acres overall. The Big Cypress reservation, with 27 ranches, includes a total of 55,000 acres dedicated to beef-cattle production. Cattle on the reservations are primarily Brangus, but their lineage dates back to the first cattle Spanish explorers brought to Florida in 1521.
The sub-tropical environment offers advantages for cattle ranching, but also presents unique challenges. Forage generally grows vigorously for example, but the nutritional value of forage adapted to the area tends to be relatively low, and ranchers need well-designed supplement programs.
At the recent Academy of Veterinary Consultants (AVC) summer conference, Aaron Stam, a Federally Recognized Tribal Extension Agent for the Seminole Tribe in South Florida, discussed how he and Seminole ranchers work to improve production efficiency in their unique environment. Stam grew up in Iowa and studied agriculture at Truman State University in Missouri. He worked in the ag industry around the Midwest and spent time teaching agriculture at a technical center in Maine, before landing in South Florida as an Extension agent working with the Seminole reservations. His responsibilities include agriculture – primarily beef cattle – and 4-H Youth Development. He currently coordinates several field trials with the University and the Seminole tribe.
In his capacity, Stam works closely with Alex Johns, who serves as the Seminole Tribe’s natural resource director and CEO of the cattle operation. As a University of Florida employee, he also has ready access to agricultural research expertise and resources.
Stam says that following a mild winter in 2014, forage was abundant but cows showed signs of declining health. In addition to poor reproduction rates and a spike in abortions, the ranchers saw cows declining in body condition, lack of appetite and anemia, and ultrasound exams showed excess uterus fluid at the time of pregnancy checking. The team tested soils and forage samples and conducted liver biopsies on affected cows, and ruled out poisonous plants and mineral deficiencies as causes for the problems. The problem remained a mystery until a visiting veterinarian from Kentucky suggested the signs resembled fescue toxicosis.
There is no fescue grown in the area, and most of the improved pasture on Seminole ranches features Bermuda or Bahia grass. With help from the University of Florida and Biomin, the team began testing and found high levels of mycotoxins in the local forages, especially in Bermuda grass, in low, wet areas during the cooler seasons.
Initial mycotoxin testing detected zearalenone, a mycotoxin associated with infertility, embryonic death and abortion in cattle. Over two years of testing, the toxin was most prevalent in common Bermuda grass, with prevalence as high as 87% of pastures during the winter and spring, particularly in lower, wetter pastures. Further testing also found zearalenone in Bahia grass pastures, but at a lower prevalence of around 27%.
Stam and Johns, utilizing Seminole Board owned cattle, ran a two-year controlled trial using Biomin’s Biofix Plus supplement to mitigate effects of mycotoxins and saw significant improvements in pregnancy rates, and calf weaning weights on low-wet pastures improved by an average of 53 pounds.
Stam points out that Bermuda grass is present in many improved pastures across much of the Southeast, so the problem could be more widespread than realized.
In addition to studying mycotoxins in the area forages, Stam works with Seminole ranchers on systems for managing smut grass, an invasive Asian species that has become a persistent problem in South Florida pastures. Most ranchers focus on controlling the grass with herbicides, at considerable expense.
Stam’s project explores an approach that lets cattle do the work while also capturing nutritional value from the smut grass. With assistance from the Seminole Tribe, he’s conducting a competitive rotational grazing field trial on the Brighton reservation. The two-year trial, which began in the summer of 2017, involves intensive grazing, rotating a group of 36 heifers between five-acre paddocks every seven days.
Smut grass, once mature, is unpalatable and has little to no forage value for cattle. Research has shown though, that young smut grass shoots, at three to four weeks of age, has palatability and nutritional value similar to bahia grass. The research team designed the rotational grazing system to exploit that opportunity by increasing stocking rates and grazing pressure in paddocks as the smut grass reaches its peak forage value, then moving to the next paddock.
Though this trial, the group hopes to determine whether intensive grazing can improve utilization of forage nutrients and potentially allow ranchers to increase stocking rates. Over time, grazing programs targeting smut grass in its early growth stages could help control or at least limit the spread of the invasive weed, for the benefit of Seminole ranchers and ranchers across the region.
I’m a Drover
Federally Recognized Tribal Extension Agent, University of Florida and Florida Seminole Tribe