published in


June 2017

Research Update

For questions or comments regarding this publication contact: The Range Cattle REC, University of Florida, IFAS

The UF/IFAS Range Cattle Research and Education Center, has enjoyed a long history of service to the Florida Cattlemen. Since 1941, our research efforts have focused on relevant problems impacting beef production throughout Florida. Unique among the UF IFAS RECs, our focus is on a single clientele group, the owners and managers of Florida’s grazinglands. At our Center, we address important issues spanning a broad scope of overlapping topics relevant to Florida’s grazinglands, such as forage management, fertilization, soil and water, beef cattle management, invasive animal and plant management, wildlife, and the economics of livestock and forage production.

Presently, the Center houses 7 faculty programs with 20 support staff including biological scientists, technicians, program coordinators, and administrative support personnel. In addition to research and extension projects, the Center’s faculty mentor numerous MS and PhD graduate students and international exchange scholars. This article provides a highlight from each of the Center’s faculty regarding work they are presently involved with in response to the research priorities of the Florida Cattlemen’s Association.

John Arthington
Professor and Center Director, Beef Cattle Nutrition and Management

The influence of dietary pH on taste or “mouth feel” is linked.  Anionic salt supplements impact the taste of a diet. This is likely due to the highly acidic result of the anionic-salt formulated supplement.  Additionally, soluble sources of trace metals may also create a taste or “mouth feel” effect.  In our studies, we have experienced this impact in models involving young beef calves, who are reported to have 2.5X the number of taste buds compared to humans.  This allows for a larger range in flavors and thus potential taste aversions (unpublished data; Yale University, College of Nursing).

Related to this phenomena, our research team has attempted to devise management technologies to improve the trace mineral nutrition of pre-weaned calves with the central aim of improving post-weaning health and performance.  As an alternative to traditional creep feeding systems, we have illustrated that limited creep, in amounts < 0.5 kg/d, result in a behavioral association of humans and feed, acclimation to concentrated feedstuffs, and improved trace mineral status.  In our initial studies, we discovered that calves provided creep-feed without trace mineral fortification had greater voluntary supplement intake compared to calves provided the same creep supplement but fortified with trace minerals (Moriel and Arthington. Journal of Animal Science. 2013). Visually, calves consuming these mineral-fortified supplements appeared to exhibit ‘taste-aversion’ to the feed. We questioned the possibility that the highly-soluble trace mineral sources used in the formulation (primarily sulfate sources) were creating a “metallic taste” in the calves’ mouth, thus reducing voluntary intake.  Following these initial experiences, we sought to examine various sources of trace minerals that might improve voluntary supplement consumption with a central focus on mineral solubility. One trace mineral source, called hydroxychlorides, is purported to be less soluble at neutral pH compared to most sulfate and organic alternatives. We hypothesized that the low solubility of these ingredients would improve preferential intake of mineral concentrated supplements.

To test this hypothesis, two experiments were conducted to evaluate the preferential intake of supplements fortified with three different sources of copper, zinc, and manganese (sulfate, hydroxychloride, or organic; Caramalac et al. Journal of Animal Science. 2017). In each experiment, calves had free-choice access to each of the 3 different formulations and preferential intake (selection for intake) was measured. In Experiment 1, the formulations were created as mineral-concentrated feed supplements, such as the limit-fed creep feeds from our earlier studies. In Experiment 2, the formulations were created as salt-based mineral supplements, such as those commonly used for grazing cattle in Florida.  In both experiments, calves preferentially consumed the supplements formulated with the hydroxychloride forms of copper, zinc, and manganese compared to the sulfate and organic alternative. These results suggest that the source of copper, zinc, and manganese will impact supplement intake behavior among beef calves. This new information will increase supplement formulation strategies aimed at improving the mineral nutrition of Florida beef calves.

For more information contact John Arthington at jarth@ufl.edu.

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Brent Sellers, Associate Professor and Associate Center Director
Jose Dias, Graduate Research Assistant
Pasture and Rangeland Weed Management

In recent years there has been a lot of variability across the state with regards to smutgrass control with hexazinone (Velpar/Tide Hexar/Velossa), and we believe it may be due to insufficient or excessive rainfall following hexazinone application.  However, we do not fully understand how much rainfall is needed to incorporate the herbicide into the soil, nor how much rainfall results in reduced control or failure.

Preliminary greenhouse and field studies were conducted in 2016 to evaluate the effects of rainfall after hexazinone application on smutgrass control. Smutgrass plants were established in gallon-sized pots in the greenhouse for at least four months prior to hexazinone application at 1 lb/acre. After the hexazinone was allowed to dry to four hours, rainfall was simulated at 0, 0.25, 0.5, 1, 2, 4, and 8 inches. To evaluate the effects of rainfall under field conditions, a smutgrass infested bahiagrass pasture was treated weekly with hexazinone at 1 lb/acre beginning the last week of April and ending the last week in August. Rainfall was collected weekly to evaluate the effects of rainfall on smutgrass control.

Data from the greenhouse study indicated that the amount of rainfall after hexazinone application significantly impacts the control of giant smutgrass. Rainfall amounts equal to 0.25, 0.50 and 1.0 inches provided good to excellent control of smutgrass, however, rainfall greater than 1 inch provided insufficient control or complete failure. While this greenhouse data provides some beneficial information for the effects of rainfall on smutgrass control with hexazinone, we expect that soil micro- and macro-pores will be substantially different under field conditions, resulting in different levels of rainfall required for optimum control of smutgrass.

Rainfall occurred throughout the spring in 2016, resulting in early season growth of smutgrass. Nearly 1 inch of rainfall fell after our initial application of hexazinone on April 22, which resulted in approximately 65% control 30 days after treatment. However, when no rainfall was recorded the week following the April 29 application, only 20% smutgrass control was observed.  Only 50% control was observed following application on June 3 when over 5 inches of rainfall were recorded the week following application, and after July 1 when no rainfall was recorded the week following application. In general, we observed acceptable levels of smutgrass control when rainfall was above 0.25 inches and below 3.0 inches under field conditions.

From these data, it appears that a minimum of 0.25 inches of rainfall is necessary to incorporate the herbicide within the root zone and rainfall in excess of 3.0 inches typically resulted in reduced control. We also observed that smutgrass control is reduced even when rainfall is recorded the second week after application, indicating that we may have a short window for rainfall to occur following hexazinone application for optimum smutgrass control. 

For more information contact Brent Sellers at sellersb@ufl.edu.

Effect of simulated rainfall on smutgrass control under greenhouse conditions following application of hexazinone at 1.0 lb/acre.

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Raoul Boughton
Assistant Professor, Range Science and Wildlife Ecology

There are two major periods of reproductive concern in cow-calf operations that are responsible for the largest loss in return for producers. The first being inability of a cow to become pregnant and/or early embryonic death, and the second, calf loss that occurs from confirmed pregnancy to weaning.  Calf loss from pregnancy diagnosis to weaning can range from a 3% up to 24% across Florida herds, with an average of 8%.  In most cases losses are unexplained and unquantified. The causes possibly include mineral deficiencies, reduced immunocompetence, diseases, genetic disorders, poor maternal behaviors, and predation, to name a few.  But what are the really important calf loss causes?  The fact is we don’t know! You ask why not?  Because it is really hard to study the on ranch effects, difficult to efficiently and effectively monitor calving, and most calf loss occurs within hours or days of birth. Calf loss is a serious and reoccurring economic loss to beef cattle production in Florida, and severely understudied.

The average reported loss of 8% to the Florida industry equates to 64,000 calves a year (based on 800,000 calves) and the number could be much higher some years.  A reduction in calf loss of just 1% on average is millions of dollars recovery to the industry. Quantifying causes of calf loss is essential for Florida cattlemen to make improvements and position the industry to make highly informed production decisions and implement measures to improve overall production and economic return.

Excitingly, we now have the technology (birthing transmitters) to remotely signal when parturition is occurring, help easily find the calf, and increase our understanding of calf loss, but has previously been very limited to study in a ranch setting.  These sensors send signals to a base station that can monitor several hundred acres of ranch for sensor expulsion events immediately prior to birth. The sensor continually records temperature and uses a decreasing temperature profile as a trigger a signal that the sensor has been pushed out of the birthing canal. The base station is connected to the internet and informs the user via a website and text messages that an event has occurred. Then the location of the sensor can be tracked. In this way the Rangeland Wildlife and Ecosystem Program  and collaborative partners can monitor calving events, check on the calf and cow, immediately tag calf with mortality tracking devices and overtime document all causes of calf loss from late gestation all the way through to weaning.  With funding from the Cattle Enhancement Board Inc. over the next three years we will be monitoring calf-loss directly on Florida ranches. The first herds will be monitored starting in 2017.

The information we will gain from this extensive study will focus our future resources to provide the greatest economic return to producers through increasing calf survival. Without new technology to help gather important information we would be unable to conduct this type of work. Stay tuned for future updates and visit www.rangelandwildlife.com for more information.

For more information contact Raoul Boughton at rboughton@ufl.edu.

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Philipe Moriel
Assistant Professor, Beef Cattle Nutrition and Management

In this edition, our nutrition program would like to highlight:

(1)          Decreasing the frequency of supplementation consists of providing the same weekly supplement offer in less feeding events to reduce costs associated with labor, equipment, and fuel. Unfortunately, we demonstrated in 2015 that steers supplemented 3 times weekly were more stressed at the time of vaccination, had a 0.60 lb/day lower average daily gain, and reduced response to vaccination compared to steers supplemented daily. To address this issue, we designed a study that investigated if a gradual reduction on frequency of energy supplementation following vaccination could prevent these detrimental effects on growth and immunity of beef steers. We observed that feeding calves daily until the last round of vaccinations (approximately 14 days after weaning), and then decreasing the frequency of concentrate supplementation to 3 times weekly until the end of preconditioning (42 days after weaning) reduced feeding costs and alleviated the stress response leading to better growth and immunity compared to calves supplemented 3 times weekly during the entire study. This strategy allows producers to reduce feeding costs while maintaining optimal growth performance of calves.

(2)          Nutrient deficiency often occurs in animals provided forage-based diets due to seasonal variation in forage quality and quantity, which not only reduces reproductive success of cows, but also calf performance after birth. Unfortunately, all published studies were conducted with bos taurus cows grazing cool-season forages, and not with cows having bos indicus genetic influence and consuming low-quality, warm-season forages that represent most pastures in FL. It is unknown if similar results will be observed in our environmental conditions. Thus, through the support of FCA, we will evaluate the impact of different nutritional management of pregnant cows on future performance of their calves.

Experiment 1 begins in May 2017, and will evaluate if year-round supplementation of molasses or range cubes will increase body condition score at calving and trace mineral status of cows throughout the year, which will increase their pregnancy rates compared to cows supplemented with molasses during Fall/Winter season only. Also, year-round supplementation will improve calf development during pregnancy, and then, calf health and growth following birth. Experiment 2 begins in September 2017, and will evaluate if energy and protein supplementation of cows during the entire late-gestation (1 lb/day of supplement for 90 days before calving) will increase reproductive success of cows, calf development during gestation and performance after birth to levels higher than the cost of this supplementation strategy. We will also investigate if concentrating cow supplementation during their period of lowest nutrient demand (first 30 days after weaning) will be more cost-effective than cows supplemented during the entire late-gestation period.

For more information contact Philipe Moriel at pmoriel@ufl.edu.

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Chris Prevatt
Regional Specialized Agent II, Livestock and Forage Economics

The expansion of the U.S. cattle herd has begun increasing the supply of beef which has created shrinking revenues for cattle producers across Florida. In order to weather the storm of herd expansion many producers will have to begin monitoring their production costs more closely as profitability will be challenged in the years ahead. The livestock and forage economics program at the Range Cattle REC has begun working with ranchers on ways they can reduce their cost of production and monitor profitable outcomes.

Some of the ways we are doing this is by developing more extensive cattle and forage budgets that can be used to help cattle and forage producers better analyze their operations. Due to the the unlimited combinations of animal and forage production practices, production costs, and market prices received by cow-calf producers many different profitable and unprofitable outcomes can occur. Thus, an understanding of which combinations are profitable will help guide cow-calf producers to make plans and decisions that will improve their operation.

Cattle and forage producers can make more informed management and marketing decisions when they use enterprise budgets and other economic decision aids for their operation. Cow-calf, forage, replacement heifer, stocker cattle, and bull 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 enterprise budgets and decision aides enable producers to examine their expected levels of performance and cost. This prior planning provides cow-calf producers with the necessary economic information and time to make management adjustments that will result in more profitable outcomes.

For more information contact Chris Prevatt at prevacg@ufl.edu.

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Maria Silveira
Associate Professor, Soil and Water Science

Biosolids have clear agronomic benefits, but concerns over nutrient accumulation in soils and subsequent impacts on water quality can limit land application in Florida. The project described in this article addresses FCA Priorities # 9 “Land Application of Biosolids on Pastures” and # 1 “Fertilization (Alternative Fertilizer Sources). The specific objectives were (1) to select, evaluate, and thoroughly characterize biosolids materials that represent the most common sources applied to Florida pastures, (2) to establish a field trial designed to evaluate the agronomic benefits of biosolids application on forageproduction, and (3) to obtain and install equipment to monitor potential impacts of biosolids application on water quality. A field experimental area was established at the UF/IFAS Range Cattle REC on an established bahiagrass pasture. The specific location was chosen to represent a typical low-fertility soil condition that most cow-calf operations experience in South-Central Florida. Three biosolids materials were selected for the field study: class AA heat-dried pellets, class B St.Pete cake, and class B Bradenton 1 cake. Biosolids were applied either alone or in combination with biochar (a fine-grained carbon-rich residue produced through the pyrolysis of woodbiomass). Because biochar can act as a strong sorbent application of biosolids amended with biochar may provide multiple benefits including better nutrientutilization, which may translate into greater forage production and nutritive value, while minimizing nutrient losses. In addition, the inclusion of carbon rich materials such as biosolids and biochar are expected to improve soil biological and physical properties resulting in improved overall soil quality conditions. Control treatments included plots receiving inorganic commercial fertilizer (ammonium nitrate + triple superphosphate alone and in combinations with biochar) and pastures receiving no biosolids, fertilizer, or biochar. Preliminary forage, water, and gas quality samples were collected and analyzed during the 2016 growing season. Groundwater level and weather data have also been continuously monitored. During the first phase of this project, significant efforts and investment have been placed on two main priorities: 1. documenting soil, forage, water, and gas baseline data, and 2. instrumenting the experimental area. Treatments were re-applied in April 2017 and the study is expected to continue for at least 3 yr (2016-2018).

For more information contact Maria Silveira at mlas@ufl.edu.

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Joao Vendramini, Associate Professor
Forage Management

Fertilizer is one of the most costly inputs in cow-calf production in Florida, therefore, my research program has focused on increasing fertilizer use efficiency in forage production. Limpograss is one of the most important forage species for cow-calf production in South Florida, therefore, a research project, funded by the Florida Cattle Enhancement Grant, was established to evaluate nitrogen (N) use efficiency of four limpograss cultivars (Gibtuck, Kenhy, Floralta, and 1). In 2016, Gibtuck had the greatest forage production, followed by Kenhy and 1, and Floralta had the least forage production at Ona. In Gainesville, Gibtuck and Kenhy had the greatest forage production, followed by Floralta and 1. Gibtuck had the greatest forage production at high (80 lb N/acre) and low (40 lb N/acre) fertilization levels. In addition, this research project tested the gene expression of 3 genes, rubisco (rbcs), Dof 1, and glutamine synthetase (GS), which are related to N use efficiency. Gibtuck and Kenhy had similar rbcs and GS expression but differed from Floralta and 1. This preliminary information indicates that the use of molecular markers may be an effective tool to select limpograss plants with greater N use efficiency. Additional genes will be investigated and plants with greater gene expression may be selected and multiplied for future selection in 2017.

Concerns have been raised regarding the potential impacts of insufficient potassium (K) fertilization and bahiagrass pasture decline in Florida. Therefore, two studies were conducted in 2014 and 2015 to determine the effects of K and N fertilization on bahiagrass forage production, nutritive value, and persistence. A combination N fertilization levels [0 (control), 50 lb N/acre (applied in May), or 100 lb N/acre (split into one application of 50 lb N/acre in May and the remaining 50 lb N/acre in August)] and K fertilization levels (0 or 50 lb K2O/acre) were tested on bahiagrass plots. Potassium fertilization did not affect forage production, crude protein, or digestibility; however, tissue K concentration increased from 1.0 to 1.1%. In addition, root-rhizome mass increased with K fertilization at the control N fertilization level. Although K may not be the most limiting nutrient in bahiagrass pastures with relatively low N fertilization, it plays an important role in pasture below ground reserves and persistence. The second study was conducted to test the correlation between tissue K concentrations and forage production in bahiagrass. Forage production was increased with tissue K concentration up to 1.4%; however, the tissue K concentration was highly dependent on N fertilization. It was concluded that tissue K concentration is variable and affected by N fertilization, and should not be used as a single indicator of bahiagrass K status.

For more information contact Joao Vendramini at jv@ufl.edu.

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