THE FLORIDA CATTLEMAN AND LIVESTOCK JOURNAL
THE FLORIDA CATTLEMAN AND LIVESTOCK JOURNAL
For questions or comments regarding this publication contact: The Range Cattle REC, University of Florida, IFAS
Selenium (Se) is a trace element that is essential in small amount for humans and animals, but not plants. The lack of Se can lead several disorders in cattle with the most widely recognized being white muscle disease in calves. Other problems include muscular weakness, reduced weight gain, diarrhea, abortions, retained placenta and diminished fertility. Selenium toxicity can sometimes be a problem and is the only nutritionally essential trace mineral that is sometimes found in toxic concentrations in forages grown in the US. Nonethless, Se-deficient forage is much more common than cases of Se excess. In a survey of 253 cow/calf operations in 18 US states, over 18% were classified as marginally or severely Se deficient by blood Se parameters. Among the states analyzed, those located in the southeast region had the greatest percentage of operations classified as marginally or severely Se deficient (42.4%).
One potential method for addressing Se nutrition in grazing cattle is the implementation of pasture Se applications with the intent of increasing plant Se content and thus the Se status of cattle grazing these forages. This strategy is is called “biofortification”. By definition biofortification is a strategy to increase the nutrient content of food. In Florida, spraying bermudagrass with Na selenate at Se application ranges of 49 to 196 g Se/acre (via Na selenate) resulted in substantial increases in forage Se content by 2 wk after application, decreasing rapidly by 12 wk post-aplication. Feeding forages grown on Se-fertilized hay fields impacts both Se status and performance of grazing cattle. In a study conducted at Oregon State University, weaned calves were fed Se-fertilized alfalfa hay over a 7-week period. Calves consuming these hay treatments experienced a linear increase in whole blood Se concentrations as Se application rate (and Se content of hay) increased.
As part of a graduate reseawrch program, Julina Ranches produced a high-Se hay crop by spraying a Jiggs bermudagrass hayfield with Na selenate at a rate of 105 g Se/acre. Selenium content of hay, harvested 8 wk after Na selenate application, was greater for Se-treated vs. control pastures (7.73 ± 1.81 vs. 0.07 ± 0.04 ppm DM; P <0.001). Using a pair-feeding study design, Se status was evaluated in calves fed this this hay crop, the same amount of Se from Na selenite, or no Se. Liver Se concentrations remained unchanged for calves receiving no supplemental Se, but were increased (P < 0.001) in calves receiving both high-Se hay and Na selenite treatments. Calves receiving high-Se hay had greater (P < 0.05) liver Se concentrations on d 21 and 42 than calves receiving Na selenite. Of notable interest, this difference was attributed only to calves consuming < 3 mg Se daily. From these initial data, we hypothesize that there is a differential availability of Se in forage vs. inorganic sources dependent upon the total daily intake with a critical point of approximately 3 mg/d in beef calves. We are currently examining these data further in both periparturient cows and calves.
For more information contact John Arthington at firstname.lastname@example.org.
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Associate Professor and Associate Center Director, Weed Science
Limpograss is an important component to nearly every ranch in south central Florida. Like all other forages, weed management is necessary to obtain optimum yield for both grazing or hay production. While most of our forages are tolerant to many of the herbicides available to weed control, limpograss is often regarded as the most sensitive to herbicide damage. This stems from the early 1980s when limpograss was planted and severely impacted by 2,4-D at planting; the stand was lost and the general recommendation from that point forward was to not apply any product containing 2,4-D to limpograss pastures and hayfields. Recent evidence on the sensitivity to established limpograss has revealed the opposite; limpograss tolerated high rates of 2,4-D with little to no yield loss when applied in the early spring. This led to research that was conducted over the past two years where we examined the effect of various herbicides on limpograss at different times of the year (late fall, early spring, and mid-summer), in response to fertilizer timing (before, during, or after herbicide application), and in response to limpograss regrowth height (6, 12, 24, and 36 inch regrowth). The regrowth height and fertilizer timing studies were conducted during the summer. Our hypothesis was that limpograss would be more tolerant to herbicides during the fall and spring versus the summer, fertilizing before herbicide application would result in more injury, and that taller limpograss would be more tolerant to herbicide application. Herbicide treatments included Banvel at 24 oz/A, 2,4-D amine at 64 oz/A, WeedMaster at 48 oz/A, GrazonNext HL at 24 oz/A, Escort at 0.3 oz/A, Pasturegard HL at 24 oz/A, Chaparral at 3 oz/A, and Velpar at 32 and 64 oz/A. Limpograss biomass was collected from plots 90 days after treatment, except for the late fall application which was harvested during the following spring when normal haying operations typically occur. In general, we found that time of year of application had little influence on the response of limpograss to herbicide treatment. However, we did observe that biomass was higher when herbicides were applied during the summer months compared to spring and fall, except for 2,4-D amine and Pasturegard HL. Limpograss tolerance to herbicides was not dependent on fertilizer timing nor regrowth height. In the fertilizer timing experiment, limpograss yield loss did not exceed 18% with any herbicide treatment compared to Banvel, and yield from plots treated with Escort or Chaparral was greater than plots treated with Banvel. Regrowth height also had no influence on limpograss tolerance to herbicides, but 2,4-D resulted in 25% yield loss compared to Banvel. Limpograss biomass from all other herbicides, except Velpar, was similar to limpograss treated with Banvel. In all three experiments (time of year, fertilizer timing, and regrowth height), Velpar caused the most injury and resulted in 50 and 80% yield loss when applied at 32 and 64 oz/A, respectively. In essence, we determined that our hypothesis was incorrect, and that limpograss is much more tolerant to herbicides than previously thought, at least by 90 days after treatment. Although 2,4-D at 64 oz/A resulted in 25% yield loss in one of the studies, the resulting yield loss that could occur from weed competition would likely be much greater. Since Banvel can be weak on large dogfennel, the ability to use other herbicides is a great benefit to increase weed control and improve grazing and hay quality. Look for more details on this research in the August Ona Report.
For more information contact Brent Sellers at email@example.com.
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Assistant Professor, Range Science and Wildlife Ecology
Research on consumer trends shows that world consumers, including Americans, are increasingly interested and concerned about the social, economic, and environmental impacts of the beef industry. In response to these concerns an international group addressing sustainability of the beef value chain was formed, The Global Roundtable for Sustainable Beef (GRSB: www.grsbeef.org), and more recently, the United States Roundtable for Sustainable Beef (www.usrsb.org). The GRSB and USRSB are multi-stakeholder initiatives developed to advance continuous improvement in sustainability of the beef value chain. Producers, commerce, processing, retail, and civil society members make up the GRSB and USRSB, including Cargill, McDonalds, JBS, and NCBA. The GRSB has developed Principles and Criteria of sustainable beef that cover 5 broad topics: Natural Resources, People & the Community, Animal Health & Welfare, Food, and Efficiency & Innovation. The vice president of Cargill Value Added Meats and interim chair of USRSB, Nicole Johnson-Hoffman, states:
“For the first time, the entire U.S. beef value chain, including representatives who raise cattle and produce, market and sell beef, in addition to representatives from the NGO community and allied businesses, are coming together to establish metrics and criteria that will be used to benchmark the present and help measure improvements in the sustainability of American beef going forward.”
The big question is - How do we provide documentation for sustainable beef in an economical, feasible, and meaningful way? Because of the renown of Florida rancher’s environmental stewardship and cow-calf operations, Florida was identified as a location for one of the first pilot projects on indicator development.
I teamed up with MacArthur Agro-ecology Research Center (MAERC; Gene Lollis, Jane Cant, Dr. Betsey Boughton & Dr. Hilary Swain) and conducted a Florida Indicator Pilot Project to identify indicators and metrics relevant to documenting sustainability for Florida Cow-Calf operations. The pilot project was funded by World Wildlife Fund, a member of GRSB. The main purpose of the pilot project was to investigate a feasible way for ranchers to document and measure their activities that are relevant to the five broad GRSB sustainability principles. The team developed questions that a rancher would be able to answer and document relatively easily. The team also realized that some questions might be difficult for ranchers to answer due to privacy concerns, and one section was devoted to how willing would you be to undertake certain activities or divulge certain information. As the survey was being developed the team used important references such as the FDACS Water Quality BMP manual and NCBA sustainability analysis, and existing metrics a rancher may already employ, such as forage and soil tests, and general observations of wildlife. After much iteration the pilot project included a final survey that contained 75 locally relevant questions to Florida cow-calf operations covering the five principles of the GSRB and was tested on 3-5 ranchers.
On April 29th 2015, several staff of World Wildlife Fund, several Florida Cattlemen, and the Director of Sustainability at McDonalds joined the UF-IFAS/MAERC team at a meeting held at Buck Island Ranch to discuss the findings of the pilot project (Photo 1). Four ranchers completed the survey and provided excellent feedback that will be used to continue indicator development. In July 2015, the first General Assembly meeting of the US Roundtable for Sustainable Beef will be held in Denver, CO and I have been invited to attend and present the findings of the Florida Indicator Pilot Project, and be a member on the USRSB working group for indicators of sustainable beef.
Please visit our program’s website at www.rangelandwildlife.com for a complete report on the Florida Indicator Pilot Project. I anticipate that this effort will continue to expand to meet the consumer demand for documentation for sustainable beef, and UF IFAS RCREC will continue to work together with ranchers and allow engagement in the process.
Photo 1. Attendees of the Florida Cow-Calf Sustainability Indicator Discussion held at Buck Island Ranch on April 29, 2015. Back row left to right: Robert Gukich (LWLA), Alex Johns (Seminole Pride Beef), Jimmy Wohl (Rafter T Ranch), Gene Lollis (MAERC), Tim Hardman (WWF), Jim Strickland, Ben Weinheimer (Texas Feeders Association), Flint Johns (Lykes Bros Inc), Arnie Sarlo (S & C Ranch), and Jim Handley (FCA). Front row left to right: Betsey Boughton (MAERC), Nancy Labbe (WWF), Michele Banik-Rake (McDonalds), Hilary Swain (MAERC), Carey Lightsey (Lightsey Cattle Co.), Carlos Saviani (WWF), and Raoul Boughton (UF IFAS RCREC).
For more information contact Raoul Boughton at firstname.lastname@example.org.
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Assistant Professor, Beef Cattle Nutrition and Management
Feed costs account for 70% of variable costs of beef production. In the cow-calf sector, 90% of feed consumed by the cow is used for maintenance, a non-productive function. Thus, winter feed costs account for 40 to 50% of variable costs of the cow-calf enterprise. Improvements in feed efficiency by identifying and selecting animals with superior ability to convert feed into meat will have a large impact on profitability of beef cattle operations.
Recently, a lot of attention has been given to residual feed intake (RFI) as a trait to use in selection programs to improve feed efficiency. Cattle with low RFI are the favorable phenotype because they eat less than their contemporaries for the same body weight and growth rate. An advantage of RFI over other traits such as feed:gain ratio is that RFI is not related to growth rate and mature size, which will not result in larger cows requiring more feed for maintenance. Several seedstock breeders and bull test stations across the United States are utilizing RFI to identify cattle with superior feed efficiency.
However, there is conflicting research as to whether low RFI cattle actually use nutrients more efficiently. Previous studies have reported that more efficient low RFI cattle have improved feed digestion and less feed energy lost as methane than less efficient high RFI cattle. But, low RFI cattle retain less energy as fat and muscle than high RFI cattle. These differences in feed digestion, methane production, and retained energy could be caused by the difference in feed intake between low and high RFI cattle, as low RFI cattle consume 20% less feed than high RFI cattle. This suggests that RFI may not be identifying cattle with biological differences in their ability to convert feed to meat. Therefore, a study was conducted to determine the ability of low and high RFI cattle to convert feed energy into energy deposited as fat and muscle when feed intake was the same. The results of this study will clarify whether RFI identifies cattle with biological differences in their ability to convert feed to meat.
Feed intake and growth rate were measured on 45 Angus heifers to calculate RFI. Eight low RFI heifers and 8 high RFI heifers were selected from the group of 45 heifers to measure energy conversion at similar levels of feed intake. Both low and high RFI heifers were fed at 2X, 1X, and 0.5X expected maintenance energy requirements to measure feed digestion, energy lost as methane, and energy lost as heat. From these measurements efficiency of feed energy use and actual maintenance energy requirement was calculated. There was no difference in efficiency of feed energy use or actual maintenance energy requirement between the low and high RFI heifers. The results of this research indicate that RFI identifies cattle that eat less but do not use nutrients more efficiently. Thus, caution should be taken when using RFI as selection trait to improve feed efficiency.
For more information contact Phillip Lancaster at email@example.com.
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Regional Specialized Agent, Livestock and Forage Economics
The livestock and forage economics program at the Range Cattle REC has been working toward developing cattle and forage budgets that may be used to help cattle producers better analyze their operations to be more profitable.
Many different outcomes, both profitable and unprofitable, can arise from the unlimited combinations of animal and forage production practices, production costs, and market prices received by cow-calf producers. Thus, an understanding of which combinations are profitable will help guide cow-calf producers to make plans and decisions that will improve their cow-calf business.
Cow-calf producers can make more profitable management and marketing decisions by using enterprise budgets and marketing information. Forage and cow-calf budgets have been developed that can be modified for an individual cattle producer. These budgets allow an individual to evaluate potential outcomes for their operation. Also, a decision aid that projects cow-calf profitability based on projected animal performance, production costs, and market prices was developed. This decision aid allows cow-calf producers to analyze the different variables that affect cow-calf profitability to determine what combination of levels of animal performance, production costs, and market prices are profitable. The tables which include a sensitivity analysis provide a visual for producers to identify the profitable outcomes using their base projections. Producers then have the opportunity to use their individualized projections to formulate plans for their cow-calf operation to be profitable for the coming year.
The use of the enterprise budgets and decision aides enables producers to examine their expected levels of performance and develop projections for the next year. The prior planning using these budgets provides cow-calf producers with the necessary economic information and time to make management adjustments that will result in a more profitable outcome.
For more information contact Chris Prevatt at firstname.lastname@example.org.
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Associate Professor, Soil and Water Science
The research emphasis of the Soil and Water Science Program at the RCREC includes soil fertility, nutrient management, and environmental services associated with cultivated and native grazinglands. To address FCA Research Priority 6 (Ranching Activities – Impacts on the Environment), in 2014 significant effort was placed on understanding soil carbon (C) dynamics in grazingland ecosystems and the impacts of pasture management on soil C sequestration and greenhouse gas emissions. Because of their large extent and diversity, grazinglands have significant impacts on the earth’s C and can potentially sequester large amounts of atmospheric CO2 and play an important role on climate change mitigation. However, estimates of the contribution of pasture management on potential soil C sequestration remain unclear, particularly in subtropical regions. Our current projects are focused on better understanding the potential short- and long-term impacts of grazingland intensification (e.g. fertilization, grazing management, and introduction of highly productive forage grass and legume species) on soil C stocks and characteristics. Specifically, we are looking at pasture management strategies that can be manipulated to enhance soil C sequestration potentials, without negatively affecting productivity or ecosystem function. The extent soil C changes in response to improved pasture management varies depending upon the region or management practice. Adoption of proper fertilization and grazing management regimens, for instance, represent viable alternatives by which C sequestration rates can be enhanced in grazing lands; however, overgrazing and poor soil fertility management may result in soil C depletion. Our efforts in this area have resulted in 2 PhD thesis and 3 peer-reviewed publications last year. These publications demonstrated that well-managed pastures promote soil C sequestration. In addition, because pasture management practices aimed at enhancing soil C stocks are generally beneficial to forage production, they can also improve soil quality and fertility and, consequently increase productivity.
Photo 1: In-situ soil CO2 flux measurement in pastures.
For more information contact Maria Silveira at email@example.com.
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Joao Vendramini, Associate Professor
The use of warm-season legumes has been suggested as an effective alternative to fertilizer for supplying nitrogen to warm-season grass pastures via biological N2 fixation. However, there are few warm-season perennial legumes that are persistent under grazing and adapted to South Florida. Pinto peanutis a warm-season perennial legume, propagated by seed, with documented persistence on acidic soils with low fertility, and it may be feasible to incorporate it into extensively grazed pastures based on warm-season perennial grasses in Florida. In 2013, two experiments were established at the Range Cattle Research and Education Center, Ona, FL to evaluate production, nutritive value, and persistence of pinto peanut in South Florida. The objective of Experiment 1 is to evaluate the relationship of grazing intensity with forage and soil characteristics when pinto peanut is intercropped with Jiggs bermudagrass. Established pastures of Jiggs were overseeded with pinto peanut at 12 lb seed/acre in 2013. Treatments are Jiggs bermudagrass alone or Jiggs bermudagrass overseeded with pinto peanutand grazed to a 7 or 10-inch stubble height. Preliminary data have shown that pinto peanut maintained or slightly increased plant population when grazed at 7 inches from May to November. In addition, pastures grazed at a 7-inch stubble height had greater herbage accumulation and fewer weeds. The contribution of pinto peanut to the total forage production of the pasture was small (4-5%); however, it was noted that pinto peanut may increase overtime due to significant seed production and appearance of new plants. The cold tolerance of pinto peanut was unknown and it was observed that the growth was greatly reduced in the winter and the plants were damaged by frost; however, the plants regrew vigorously in the subsequent spring. In Experiment 2, the objective has been to evaluate planting strategies for establishing bahiagrass and pinto peanut. Treatments were bahiagrass seeded alone, bahiagrass + pinto peanut, orpinto peanut seeded alone, with or without 50 lb N/ac at planting. Argentine bahiagrass and pinto peanut seeding rates were 25 and 10 lb/acre, respectively. Preliminary data indicate that establishing pinto together with bahiagrass is a feasible management practice to have faster soil cover and fewer weeds at establishment. Pinto peanut germinated in approximately 7 days and bahiagrass occupied the open spaces in the subsequent 3 months. Collectively, the preliminary information on pinto peanut research indicates that it is a perennial and persistent warm-season legume to be intercropped in warm-season grass pastures in South Florida.
For more information contact Joao Vendramini at firstname.lastname@example.org.