VTechWorks Repository :: Browsing by Author "Pent, Gabriel J."

Browsing by Author "Pent, Gabriel J."

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Animal Performance on Toxic Tall Fescue During The Summer
Pent, Gabriel J.; Fike, John H. (Virginia Cooperative Extension, 2018-09-19)
Discusses toxic ergot alkaloids that are sometimes produced by bacteria living within many tall fescue varieties, and the effects these toxins have on livestock, particularly cattle.
Behavior and Physiological Responses of Livestock Under Different Grazing Systems
Poudel, Sanjok (Virginia Tech, 2022-04-14)
Animal welfare is a major concern among livestock producers in the U.S. Heat stress, particularly, compromises animal welfare and productivity, causing >$2B annual economic loss to producers. The presence of toxic alkaloids within tall fescue (Schedonorus phoenix syn Lolium arundinaceum, syn Festuca arundinacea) plants induces a complex of disorders collectively known as fescue toxicosis. Summer slump, a reduction in animal performance due to heat stress, is common and evident of the symptoms. Various techniques for assessing animal physiological and behavioral responses to heat stress were explored in this dissertation, with particular emphasis on fescue toxicosis and its mitigation strategies. In the first study, the physiological and behavioral responses of heifers was evaluated when grazing either toxic tall fescue with wildtype endophyte (WE) or tall fescue with a novel endophyte (NE). Heifers (n = 24) were assigned to either WE or NE pastures for a 56-d grazing study during the summers of 2020 and 2021. Heifer average daily gain (ADG), intravaginal temperature, and degree of hair shedding were recorded during the grazing period. Blood samples were collected through coccygeal venipuncture and hair was collected from the left rump for cortisol analysis. Ear, tail, and hoof temperatures were collected for each heifer using an infrared thermal imaging camera. In 2020, heifers that grazed NE tall fescue had greater (P = 0.0160) ADG over the season (0.22 vs. 0.12 kg day-1). Hair retention score was greater (P = 0.0029) for heifers that grazed WE tall fescue compared to heifers that grazed NE tall fescue across both years. Heifers that grazed WE tall fescue had decreased ear skin temperature (P = 0.0001), tail skin temperature (P = 0.0058), and hoof surface temperature (P = 0.0075) compared to heifers that grazed NE. Heifers that grazed WE had 0.3-0.9 ºC hotter intravaginal temperatures than heifers that grazed NE, especially during daytime. Hair cortisol levels of heifers that grazed WE tall fescue were greater (P < 0.0001) compared to hair cortisol levels of heifers that grazed NE tall fescue. From 1200h-1700h each day, heifers that grazed WE tall fescue spent 1.5 more (P = 0.0003) hours standing and 0.9 fewer (P = 0.0402) hours lying down compared to heifers that grazed NE tall fescue. These results suggest that heat stress and other physiological changes in heifers grazing WE tall fescue could be mitigated by renovating pastures with NE tall fescue that does not impose any negative effects on grazing animals. The second study explored the potential benefits of consuming condensed tannins as a means of negating the effects of toxic alkaloids in tall fescue. Twelve fall-born steers were assigned to one of the two diet supplement treatments - sericea lespedeza pellets (LES) or sericea lespedeza pellets mixed with polyethylene glycol (LES+PEG) for 12 weeks during the summers of 2020 and 2021. The LES+PEG treatment served as a positive control since polyethylene glycol binds tannins, rendering them inactive in the gastrointestinal system. Animal body weight (BW), hair retention score (HRS), rectal temperature, and thermographic images were collected every 4 weeks. Hair and blood samples were also collected for cortisol analysis. Fecal and urine samples were collected and analyzed for total ergot alkaloid (TEA) concentration. Steers on LES had greater (P = 0.0033) ADG compared to steers on LES+PEG in 2021, but not in 2020 (P = 0.8707). In 2021, HRS was greater (P < 0.05) for steers fed LES+PEG compared to steers fed LES. In 2020, ear skin temperature (P < 0.0001) and hoof surface temperature (P = 0.0382) was greater in steers on LES compared to steers on LES+PEG. Rectal temperatures were lower (P = 0.02905) for steers fed LES compared to steers fed LES+PEG in 2021. Plasma cortisol levels did not differ (P ≥ 0.1566) between LES and LES+PEG treatments for both years. In 2020, hair cortisol levels did not differ (P = 0.8295) between treatments while in 2021, the hair cortisol level of steers on LES+PEG was greater (P = 0.0221) compared to hair cortisol levels of steers on LES. This study indicated some changes in animal physiology in response to dietary supplements containing condensed tannins, but results were inconsistent and further studies are needed to better understand the potential benefits of tannins in reducing the effects of toxic alkaloids consumption. In the third study, behavioral and physiological responses of ewes that grazed either mid-stage hardwood silvopastures or open pasture (OP) were compared. The study site consists of 0.27-ha of black walnut (Juglans nigra; BSP) and honeylocust (Gleditsia triacanthos; HSP) silvopastures and open pasture treatments, each replicated three times. During the summers of 2020 and 2021, thirty-six Katahdin ewes were assigned to one of the treatments for a 6-week summer grazing trial. Ewe weights were recorded for two consecutive days at the beginning and end of the study and intravaginal temperatures were recorded for two consecutive days at every 3-week intervals. Trail cameras captured animal behavior. Blood was collected via jugular venipuncture. Hair grown during the trial was collected from the loin region. Blood and hair cortisol concentrations were determined by ELISA. Ewe ADG was greater in HSP compared to OP (P = 0.0456) but did not differ with BSP (P = 0.4686) across both years. Ewes on OP had hotter (P ≤ 0.0343) intravaginal temperatures than ewes on both silvopasture treatments between 1100h-1700h. Plasma cortisol level was lower in ewes on BSP compared to ewes on OP (P = 0.0400) but did not differ with ewes on HSP (P = 0.6954) across both years. Ewes that grazed OP had greater hair cortisol levels compared to ewes on silvopasture treatments both in 2020 and 2021 (P < 0.0001). In 2020, ewes on BSP spent about 20% more time grazing than ewes on OP (P = 0.0054) while in 2021 ewes on BSP spent about 36% more time grazing than ewes on HSP (P = 0.0014). Ewes on OP spent 400% more time standing than ewes on BSP (P < 0.0001) and 750% more time standing than ewes on HSP (P < 0.0001). Ewe on OP spent 20% less time lying down compared to ewes on BSP (P < 0.0001) and 33% less time lying down compared to ewes on HSP (P < 0.0001). Hair cortisol measures and intravaginal temperature sensors can be utilized as reliable and relatively non-invasive techniques for measuring heat stress response in livestock managed in extensive grazing systems.
Can Beef Be Bee-Friendly? Using Native Warm-Season Grasses and Wildflowers in Pastures to Conserve Bees
Wagner, Jennie Faith (Virginia Tech, 2020-05-29)
Over the past several decades, native and managed bee populations have decreased in the United States and worldwide. Although bee decline is attributable to several factors, habitat loss is the primary driver. Simultaneously, cattle producers in the eastern U.S. rely primarily on cool-season forages that peak in biomass production in late spring, leading to a lack of forage in the summer months and increasing the costs of cattle production. Seeding pastures with a mix of native warm-season grasses and native wildflowers could increase forage availability while also increasing available resources for bees. In this study, a mix of three native warm-season grasses (NWSGs) and 15 wildflower species was planted at the Virginia Tech Shenandoah Valley Agricultural Research and Extension Center (SVAREC). The objectives of this project were to document the establishment and species composition of NWSG + wildflower pasture mixtures, compare the attractiveness of wildflowers and weedy species to bees, and compare the bee community between NWSG + wildflower pastures and more typical cool-season grass pastures. The wildflowers in the NWSG + wildflower pastures dominated over grasses. All wildflower species that established were attractive to bees, as were some weedy species. The NWSG + wildflower treatments had the highest abundance of bees collected, with an average of 14.8 bees collected per pasture per sampling date in 2018, and an average of 12.4 bees collected per pasture per sampling date in 2019. These results indicate that with modification of establishment methods so that more grasses are present, this pasture system could be beneficial from both a cattle production and bee conservation standpoint.
Clipping Heifer Hair Coats Can Briefly Reduce Fescue Toxicosis Symptoms
Beard, Christopher T.; Pent, Gabriel J.; Swecker, Terry; Abaye, Azenegashe Ozzie (Virginia Tech, 2022-11-10)
A substantial challenge for many beef cattle producers is developing beef heifers into mature, productive cows in a timely and profitable manner. At the Shenandoah Valley Agricultural Research and Extension Center (SVAREC), fall-born replacement heifer candidates are artificially inseminated (AI) in December at 14-15 months of age with a target weight of 350-380 kg. Achieving this level of weight gain through the summer months has been difficult due to heat stress and the utilization of toxic endophyte-infected tall fescue. Tall fescue is the predominant species of forage found at SVAREC. The purpose of this project was to determine if clipping the hair coats of beef heifers would reduce the heat stress that the heifers experience during the summer months. Heifer hair coats were scored in the spring when they were approximately 9 months old and had an average weight of 200 kg in year one and 256 kg in year two. Heifers were scored on a five-point ranked scale, with a score of 1 indicating complete shedding of hair and a score of 5 indicating that no shedding has occurred. Heifers with a hair coat score of 4 or 5 were utilized for this project. The selected group of heifers scoring a hair coat score of 4 or 5 (32 in year one and 23 in year two) were randomly assigned to a control cohort and a clipped cohort. The heifers in the clipped treatment group were sheared with variable speed clippers along the body of the heifer, but not from under the belly or along the legs. Heifer hair coats were scored again at the end of the study on day 113. Vaginal temperature loggers were used to record core body temperatures every ten minutes during several sampling periods. At the conclusion of these 16-week trials, most of the control heifers retained their hair coats while the heifers that had been clipped regrew their hair coats. There was significant period by treatment interaction for the response of heifer average daily gains to clipping (P=0.0002). Average daily gains of the clipped heifers (0.4 kg/day) exceeded the average daily gains of the control heifers (0.1 kg/day) only in the first four-week period of each year (P<0.0001), but there were no differences in total seasonal average daily gain (0.3 kg/day; P=0.1631). There was significant treatment by hour interaction in the analysis of heifer vaginal temperatures (P<0.0001), with clipped heifers cooler than control heifers through most of the night and morning hours, but not in the afternoon. In conclusion, clipping heifers resulted in only short-term benefits to weight gains for heifers stocked on toxic endophyte-infected tall fescue pastures, but clipping did result in reduced core body temperatures throughout the summer months. Additional work could explore the effects of clipping heifers at regular intervals during periods of high temperatures and humidity, such as at monthly intervals.
Condensed Tannins Attributes: Potential Solution to Fescue Toxicosis?
Poudel, Sanjok; Zeller, Wayne E.; Fike, John H.; Pent, Gabriel J. (MDPI, 2023-03-14)
Tall fescue (Schedonorus arundinaceous (Schreb.) Dumort. nom. cons. Lolium arundinaceum (Schreb.) Darbysh.) toxicosis results from the consumption of alkaloids released by wild-type endophytes (Epichloe coenophiala) that live in symbiosis with the plant. Alkaloid consumption causes significant production and reproductive losses which cost the U.S. beef industry approximately $2 billion every year. Incorporating species that contain condensed tannins (CTs) into forage systems may be an effective strategy to reduce the effects of fescue toxicosis in livestock. It has been hypothesized that stable complexes formed between CTs and toxic alkaloids could help reduce their absorption through the gastrointestinal epithelia, thus reducing their toxic effects. However, it is not yet clear whether CTs are effective in reducing the effects of fescue toxicosis in grazing systems. A comprehensive literature search was carried out using Google Scholar to identify studies relevant to the research question, from which the cited articles were selected. This review covers the value and issues of tall fescue employed as useful forage, summarizes the impact endophyte-infected tall fescue can have on cattle, and sets out the current management strategies implemented to minimize fescue toxicosis. The review continues with a brief summary of tannin structure and the well-documented benefits that CT-containing forages can contribute to the productivity and sustainability of ruminant agriculture. Finally, a summary of the potential forage sources, mechanisms, and benefits of CTs in reducing the negative post-ingestion effects of fescue alkaloids in livestock is provided.
Converting pastures to native warm season grasses: forage for drought in Bedford county
Pent, Gabriel J.; Daniel, J. B. (Virginia Cooperative Extension, 2020)
Warm season grasses are most productive during summer months and have the potential to fill a large forage production gap in the southeastern US, known as the "summer slump." Native warm season grasses are well adapted to theis region's climate and soils, maintaining high productivity even in the summer months and with minimal inputs. Their deep rooting potential also has value for carbon sequestration.
Converting pastures to native warm season grasses: Summer forage and wildlife habitat in Caroline County
Pent, Gabriel J.; Daniel, J. B. (Virginia Cooperative Extension, 2021-03-01)
Native grasses can provide forage for cattle and habitat for wildlife. This publication provides a farmer's perspective on converting a tall fescue pasture to native warm season grasses.
Creating silvopastures – Some considerations when planting trees into pastures
Fike, John H.; Downing, Adam K.; Munsell, John F.; Frey, Gregory E.; Mercier, Kelly; Pent, Gabriel J.; Teutsch, Christopher D.; Daniel, J. B.; Fisher, K. Jason; Adams, Miller; Groh, Todd (Virginia Cooperative Extension, 2017)
Silvopastures — integrated tree-forage-livestock production systems — have the potential to boost farm resource use and income. These systems take advantage of the beneficial interactions among system components, add biodiversity, and increase animal comfort. The intentional and careful combining of trees and livestock in time and space can yield both short-and long-term returns and have positive environmental outcomes. In well-managed silvopasture systems, trees can reduce livestock stress by protecting them from inclement weather or by reducing ambient temperatures and radiation. They can provide marketable timber and nontimber products and improve environmental quality by reducing water runoff and capturing nutrients and by reducing animal use of surface waters.
Creating Silvopastures: Some Considerations When Thinning Existing Timber Stands
Fike, John H.; Downing, Adam K.; Munsell, John F.; Daniel, J. B.; Teutsch, Christopher D.; Mercier, Kelly; Pent, Gabriel J. (Virginia Cooperative Extension, 2016-09-30)
Discusses the concept of silvopastures, the inclusion of trees with forage and livestock production in a rotational grazing system. This system can improve forage production, animal comfort, increase farm resource use efficiency, increase farm income, and reduce environmental costs. This system is also more sustainable.
Effect of silvopasture system on fearfulness and leg health in fast-growing broiler chickens
Paneru, Bidur; Pent, Gabriel J.; Nastasi, Shawna; Downing, Adam K.; Munsell, John F.; Fike, John H.; Jacobs, Leonie (2023-02)
A silvopasture system intentionally integrates trees, forages, and livestock, allowing dual land use. These systems can provide high-quality habitat for broiler chickens; however, such systems have not been widely adopted by the broiler industry in the United States. The objective of this study was to examine the effect of silvopasture versus open pasture access on fearfulness and leg health in fast-growing broiler chickens. A total of 886 mixed-sex Ross 708 chicks in Experiment 1 (Exp 1) and 648 chicks in Experiment 2 (Exp 2) were housed in coops and had access to 16 (Exp 1) or 12 (Exp 2) 125m2 silvopasture plots (x̄ = 32% canopy cover) or open pasture plots (no canopy cover) from day 24 of age. Fearfulness was measured using a tonic immobility test (tonic immobility duration), and leg health was assessed by quantifying footpad dermatitis, hock burns, gait, and performing a latency-to-lie test on days 37-39 of age. Birds in the silvopasture treatment were less fearful than birds in the open pasture treatment. Overall, birds in both silvopasture and open pasture systems had excellent leg health. Silvopasture birds had lower footpad dermatitis scores than open pasture birds. Silvopasture birds tended to have worse gait than open pasture birds in Exp 1, but not in Exp 2. Hock burn scores and latency-to-lie did not differ between treatments in Exp 1 or Exp 2. Raising birds in silvopasture reduced fear and improved footpad health compared to birds raised in open pastures, which indicates that silvopasture systems provide some benefits for affective state and leg health in fast-growing broilers.
The effects of endophyte-infected tall fescue on production and reproductive performance parameters of beef cattle and calves
Anderson, Amber A. (Virginia Tech, 2019-12)
Beef cattle production records from two Virginia Department of Corrections herds from 2012- 2019 were analyzed to determine how the cultivar of tall fescue – toxic endophyte-infected or novel endophyte-infected – impacted cattle productivity metrics. Parameters compared were artificial insemination pregnancy rates, calving rates, body weights, and body condition scores of cows and birth weights and weaning weights of calves. The experimental design was a randomized completed block design with year as the replication. Samples of tall fescue were collected from the farm locations and tested for total ergot alkaloid concentrations. The samples from the farm with toxic endophyte-infected tall fescue all contained toxic levels of ergot alkaloids while the samples from the farm with novel endophyte-infected tall fescue indicated that half of the pastures at this location did not have toxic levels of total ergot alkaloids. Artificial insemination pregnancy rates were greater (P = 0.0011) for cows on novel endophyte-infected tall fescue (52 ± 1%) than for cows on toxic endophyte-infected tall fescue (43 ± 1%). Cows on novel endophyte-infected tall fescue had greater calving rates (94 ± 1%) than cows on toxic endophyte-infected tall fescue (89 ± 1%; P = 0.0243). Body condition scores and body weights at pre-breeding were greater for the cows on novel endophyte-infected tall fescue (P=0.0153 and P=0.0456, respectively). Birthweights were reduced for calves on toxic endophyte-infected tall fescue (34 ± 0.9 kg.) than for calves on novel endophyte-infected tall fescue (38 ± 1.4 kg.; P = 0.0257). Calves on novel endophyte-infected tall fescue had greater weaning weights (278 ± 5.9 kg.) than calves on the toxic endophyte-infected tall fescue (254 ± 5.9 kg.; P = 0.0217). Cattle production was improved on the farm with novel endophyte-infected tall fescue compared to cattle production on the farm with only toxic endophyte-infected tall fescue.
Effects of fescue cultivar on performance of beef cows grazed on summer stockpiled tall fescue pastures
Langford, Taylor Andrew (Virginia Tech, 2020-06-09)
This 2-yr experiment evaluated productivity of wild-type, endophyte-infected tall fescue (E+) and novel endophyte-infected tall fescue (NE) summer stockpiled (SS) pastures and the performance of fall-calving beef cow/calf pairs stocked on each cultivar. Fescue cultivars used were KY-31 and MaxQ for E+ and NE treatments, respectively. Pregnant Simmental x Angus cows (128 total, 64 each yr) were stratified by BW, BCS, and expected calving date and then allotted to 1 of 10 pasture groups within each yr (20 groups total, 10 per treatment). Forage growth was stockpiled from April until the initiation of strip-grazing on August 31 of 2017 and 2018. Cows grazed treatment pastures for 52 d from 23 ± 14 d prepartum to 29 ± 14 d postpartum, and calved on treatment pastures. Forage quadrats were clipped from the grazed and ungrazed portions of each pasture to determine weekly forage mass. Total ergot alkaloid (TEA) concentrations were analyzed for all pastures at the beginning of the experiment and every subsequent 2 wk for E+ tall fescue. Cow BW was recorded on 2 consecutive d and BCS determined at the start and end of the experiment. In yr 2, ultrasound 12th rib fat thickness (FT) was measured at the beginning and end of the treatment period Milk production was estimated using the weigh-suckle-weigh technique at 29 ± 14 d postpartum. Initial TEA concentrations for NE (Yr. 1 = 112 µg/kg; Yr. 2 = 632 µg/kg) were decreased (P ≤ 0.01) compared to E+ (Yr. 1 = 1831 µg/kg; Yr. 2 = 2903 µg/kg). TEA concentrations for E+ pastures did not differ (P < 0.23) by sample date. However, average TEA concentrations were greater for yr 2 than yr 1(P ≤ 0.01). Fescue cultivars were not different (P ≥ 0.06) in forage CP, Ash, Ether Extract, and grazed or ungrazed forage mass. However, differences were observed (P ≤ 0.02) for ADF, NDF, and TDN by fescue cultivar. Cow BW, BCS, and FT at the beginning and end of grazing were not different (P ≥ 0.41) by treatment. Milk production was greater (P < 0.01) for cows grazed on E+. Calving date, calf BW, calf ADG were not different (P ≥ 0.65) by treatment. Neither AI nor overall conception rates differed (P ≥ 0.23) between cultivars. Performance of fall-calving cows pre-exposed to E+ was not hindered when grazed on E+ relative to NE in a SS system.
Establishing and protecting trees in pastures
Pent, Gabriel J.; Downing, Adam K.; Fike, John H. (The Virginia Forage and Grassland Council, 2019-03)
Also includes information about the 2019 Virginia Forage and Grassland Council Winter Forage Conferences, position announcement for an Applied Forage Systems Specialist, and Fescue Field Day 2018.
Evaluating Different Methods to Establish Biodiverse Swards of Native Grasses and Wildflowers for Pasturelands
Kubesch, Jonathan O. C.; Greiner, Scott P.; Pent, Gabriel J.; Reid, J. Leighton; Tracy, Benjamin F. (MDPI, 2024-05-14)
Many cool-season pastures in the southeastern U.S. are dominated by a competitive cool-season grass, tall fescue (Schedonorus arundinaceus), and lack substantial plant diversity. Planting native warm-season grasses (NWSGs) and wildflowers (WFs) into these pastures could provide summer forage for cattle and more floral resources for pollinators. This paper summarizes field experiments designed to evaluate different spatiotemporal planting arrangements of NWSGs and WFs to improve their establishment success. The study was conducted from April 2021 to October 2023 in central Virginia (USA). Planting treatments included NWSG and WF mixtures planted: (1) together in the same space, (2) spatially separated in space (i.e., side by side), or (3) temporally separated where NWSGs and WFs were planted in difference sequences. Results showed few differences in forage mass, floral production, and botanical composition as well as stand density in 2021 and 2022. In 2023, NWSG abundance was greater where grasses were planted first or mixed with WFs. Similarly, the WF component was favored when they were planted before NWSGs. Overall, planting NWSG and WF mixes separately, either spatially or temporally, favors successful establishment and could offer more flexibility for using selective herbicides to suppress the heavy weed pressure that often accompanies these plantings.
Evaluating native warm-season grass and wildflower mixtures for beef cattle production in the Mid-Atlantic
Kubesch, Jonathan Omar Cole (Virginia Tech, 2023-12-20)
Tall fescue grasslands are the dominant form of grasslands in the North American transition zone, however, warm-season forages provide necessary forage for livestock in the summer. Pollinators require steady forage availability in the same fashion as cattle. Native warm-season grasses (NWSG) and wildflowers (WF) could be incorporated into tall fescue (TF) grasslands to improve pollinator resources within agricultural landscapes without sacrificing livestock production. This balance of ecosystem services can be considered bee-friendly beef. Previous establishment experiments suggests that bee-friendly beef is a possibility, although establishment and persistence of NWSG-WF stands warrants additional research. Three small plot experiments were conducted to evaluate different planting methods designed to optimize establishment of NWSG-WF stands. Additionally, a grazing study examined whether NWSG-WF pasture enhancement could improve animal performance in TF grazing systems. The small plot experiments experienced extreme weed competition in the establishment year, although plots with higher NWSG content had fewer weeds over time. Floral production was comparable across treatment, which suggests lower WF seeding rates can generate comparable pollinator resources. Major findings from these experiments suggested that spatial or temporal separation of NWSGWF was unnecessary to generate successful establishment, varying the ratio of NWSG-WF in seed mixtures produced similar establishment outcomes, and that adding companion crops to NWSG-WF mixtures did not improve establishment success appreciably. In the grazing experiment, animal performance was improved in the biodiverse grazing systems when heifers 3 had access to the NWSG. Biodiverse and shaded grazing systems modified animal behavior and reduced body temperature relative to control grazing systems, although only biodiverse grazing systems improved animal performance. Native WF species failed to establish within the biodiverse grazing system, but white clover provided all subsequent floral production. Establishing WF in pastures is challenging and warrants additional study on more effective weed control strategies and systems to ensure establishment success. Selecting WF for agronomic performance or breeding such plant material will be necessary to improve emergence and establishment dynamics. Ideally trait data can identify the optimal WF species for specific grazing systems. Biodiverse NWSG-WF can be highly effective at improving summer weight gain in beef cattle. Future studies should focus on finding a more optimal balance of NWSG, WF, and TF that can benefit beef cattle production, pollinator services, and ecosystem services regarding soil and water quality, as well as pasture resiliency to dynamic conditions.
Evaluation of Rotational Bale Grazing as an Alternative Winter-Hay Feeding System for Beef Cows
Thomas, Summer Payge (Virginia Tech, 2024-05-28)
Traditional methods of winter hay feeding for beef cattle often entail numerous challenges, including high labor demands, high fuel consumption, soil compaction, limited nutrient dispersion, heightened nutrient runoff risks, low forage yields, and nitrogen loss from manure. Rotational bale grazing (RBG) offers an innovative approach to winter hay feeding by strategically positioning hay bales on pasture prior to the onset of winter feeding, then allowing controlled access to the bales. However, its feasibility in the temperate climate of the Southeastern U.S. remains uncertain. Therefore, this dissertation, conducted over two years at the Shenandoah Valley Agricultural Research and Extension Center in Raphine, VA, aimed to assess the feasibility of implementing RBG in Virginia. Three pre-established sacrifice paddocks (SP) and three five- paddock rotations for RBG treatments were utilized, with cattle being winter hay-fed for approximately 60 days. The study commenced with soil grid sampling across Novel Endophyte Tall Fescue (Schendonorous arundinaceous) pastures, strategically placing hay bales in areas with the lowest Mehlich 1- phosphorus (P). Changes in Mehlich 1-P, Mehlich 1-potassium (K), water-soluble P (WSP), nitrate (NO3-N), and pH were monitored over a two-year RBG implementation period. The results indicated that bale placement did not significantly alter the spatial distribution of Mehlich 1-P concentrations, but consistently influenced Mehlich 1-K distribution. The WSP concentrations remained consistent with bale placement but decreased without. Bale placement had no significant effect on NO3-N or pH. Furthermore, this study investigated the effects of RBG on nutrient and sediment runoff in comparison to traditional SP. Artificial rainfall simulations were conducted on a SP, RBG first paddock grazed in the rotation (RBG first), and RBG last paddock grazed in the rotation (RBG last). The most significant differences were observed between the RBG first and last treatments, with forage presence in the RBG first paddock contributing to diminished runoff volume and nutrient load. Notably, the SP treatment showed no significant difference from the RBG treatment, likely due to many years of manure deposition increasing soil organic matter and water infiltration. The findings suggested that an RBG paddock grazed last in the rotation may lead to increased runoff volumes, sedimentation, and nutrient concentrations compared to an RBG paddock grazed first in the rotation. To understand the impact of RBG on forage biomass recovery, spring forage biomass was measured using ground manual samples and drone imagery. Manual samples and drone flights were conducted three times post-winter hay feeding. While the SP system exhibited the highest biomass recovery in high animal impact areas, RBG showed numerically higher biomass by the third sampling date in low animal impact areas. Drone imagery showcased potential for biomass estimation, but processing of drone images took excessive time and rendered it less feasible compared to manual samples.
Hair Cortisol as a Measure of Chronic Stress in Ewes Grazing Either Hardwood Silvopastures or Open Pastures
Poudel, Sanjok; Fike, John H.; Pent, Gabriel J. (MDPI, 2022-06-29)
Hair cortisol is a relatively non-invasive and reliable measure of chronic stress, but it has received limited use, especially in pasture systems. A two-year study was carried out to compare behavioral and physiological (intravaginal temperature, hair, and blood cortisol) responses of ewes (Ovis aries) that grazed black walnut (Juglans nigra) silvopasture (BSP), honeylocust (Gleditsia triacanthos) silvopasture (HSP), or open pastures (OP) treatments. Ewe weights and intravaginal temperatures were recorded once for every 4-week interval. Plasma and hair cortisol concentrations were determined by ELISA. Trail cameras detected animal behavior. Ewe average daily gain was greater in HSP compared with OP (p = 0.0456) but did not differ with BSP (p = 0.4686) across both years. Ewes on OP had higher (p < 0.0001) hair cortisol concentrations than ewes on silvopasture treatments both summers. Ewes on OP had ≥ 0.4 °C higher (p ≤ 0.03) intravaginal temperatures during portions of the afternoon than ewes managed in silvopasture treatments. Ewes on OP spent 500–700% more (p < 0.0001) time standing and 125–150% less (p < 0.0001) time lying down compared with ewes on silvopasture treatments. Hair cortisol measures could be an effective and relatively non-invasive technique for determining long-term chronic stress in grazing animals.
Is livestock producers' interest in silvopasture related to their operational perspectives or characteristics?
Wilkens, Philadelphia; Munsell, John F.; Fike, John H.; Pent, Gabriel J.; Frey, Gregory E. (2021-08-24)
Livestock producers' operational perspectives and characteristics are known to be associated with silvopasture adoption, but findings in the literature are mixed and contradictory. To study whether characteristics or perspectives more closely relate to silvopasture interest, 307 livestock producers enrolled in cost-share programs in Virginia, United States of America were surveyed. One hundred and thirty-nine producers responded (rate = 45%). Interest in silvopasture was measured using a Likert-type ordinal scale. Respondents reported the following operational characteristics: size in hectares, type and number of livestock, and primary or secondary occupation. Twelve Likert-type ordinal scales were used to measure the following operational perspectives: financial emphasis, cultural importance, and attitudes pertaining to operational diversification using trees. Multivariate cluster methods were used to group respondents into two classification sets, one based on operational characteristics and the other operational perspectives. Tests for significant differences in silvopasture interest between classifications in each set were conducted using non-parametric Kruskal-Wallis rank sums (alpha = 0.05). Silvopasture interest differed significantly among classifications based on operational perspectives, but not operational characteristics. Cross-tabulations of the two sets and Cramer's V test indicated that the two classification sets are unrelated. Findings suggest silvopasture interest cuts across operation type and is more closely tied to producers' perspectives, particularly views related to diversification. Technical transfer programs and stakeholder engagement should focus on matching perspectives to practice regardless of operational scale and scope.
Lamb performance in hardwood silvopastures, I: animal gains and forage measures in summer
Pent, Gabriel J.; Greiner, Scott P.; Munsell, John F.; Tracy, Benjamin F.; Fike, John H. (Oxford University Press, 2019-09-13)
The integration of trees into pasture systems can have variable effects on forage and animal growth. Some reports of these systems have indicated that animal gains are similar or better even when tree presence lowers forage yield. Forage production and animal performance were compared in black walnut (Juglans nigra L.)-based and honeylocust (Gleditisia triacanthose L.)-based silvopasture systems and open pastures in a randomized complete block design with three blocks over three summers. Cool season-based, mixed grass pastures were rotationally stocked with four to seven lambs depending on available forage. A rising plate meter was used to estimate pre- and post-graze forage mass. Forage samples of the mixed sward were collected and analyzed for nitrogen (N) and neutral detergent fiber (NDF) concentrations. Species percent cover was estimated using a modified Daubenmire approach at the same 12 points within each experimental unit every 4 wk during the study. Pre-graze herbage mass was similar (P = 0.0717) in honeylocust silvopastures (5020 ± 30 kg·ha⁻¹) and open pastures (4930 ± 30 kg·ha⁻¹) and lowest (P < 0.0001) in the black walnut silvopastures (3560 ± 30 kg·ha⁻¹). Forages in the black walnut and honeylocust silvopastures had similar (P = 0.4867) N concentrations (23.3 ± 0.4 and 23.9 ± 0.4 g·kg⁻¹, respectively), which was greater (P ≤ 0.0003) than that of the forages in the open pastures (21.0 ± 0.4 g·kg⁻¹). Forages in the honeylocust silvopasture had lower (P ≤ 0.0042) NDF concentrations (507 ± 3 g·kg⁻¹) than forages in the black walnut silvopasture and open pastures (mean = 525 ± 3 g·kg⁻¹). Forage species present in the black walnut silvopastures differed from those present in the open and honeylocust systems, which had similar composition. Despite differences in stocking rates, total lamb weight gains per system did not differ (P ≥ 0.7592) among black walnut, honeylocust, and open pasture systems (10 ± 2, 12 ± 2, and 10 ± 2 kg·d⁻¹, respectively). Silvopasture practices can improve land productivity when incorporated into cool season forage pastures.
Lamb performance in hardwood silvopastures, II: animal behavior in summer
Pent, Gabriel J.; Greiner, Scott P.; Munsell, John F.; Tracy, Benjamin F.; Fike, John H. (Oxford University Press, 2019-11-25)
Integrating trees into pastures, a practice known as silvopasture, may benefit livestock in the summertime through the provision of shade. The purpose of this project was to compare the behavioral patterns of sheep grazing in silvopastures and open pastures. Black walnut (Juglans nigra L.) and honeylocust (Gleditisia triacanothose L.) based silvopasture systems were compared with open pastures in a randomized complete block design with three blocks over two summers. Behavior measures were recorded within a replicate within a week, and these measures were taken sequentially within three experimental periods. Ewe lambs (n = 3) within each experimental unit were equipped with a wideband audio-recording device to detect prehension events. Time-lapse cameras documented sheep behavior every 60 s. In the silvopastures, the lambs spent over 90% of daylight hours within shade from trees. Lambs in silvopastures spent more time lying down than animals in the open pastures (P ≤ 0.01), while lambs in the open pastures spent more than 2 h longer each day standing (P < 0.0001). Lambs in the black walnut silvopastures spent more time grazing (488 ± 14 min · d⁻¹) than lambs in the honeylocust silvopastures (438 ± 14 min · d⁻¹; P = 0.0493) and lambs in the open pastures (417 ± 14 min · d⁻¹; P = 0.0026). There was no difference in grazing time for lambs in the latter two systems (P = 0.5597). Spectral analysis of the imagery revealed that the lambs in the black walnut silvopastures grazed more frequently than the lambs in the other systems for both years. The acoustic analysis, though limited by recorder durability to 47 complete recordings, revealed no difference in total bites taken per day (P ≥ 0.7222) or in the morning (P ≥ 0.2069), afternoon (P ≥ 0.5816), and evening periods (P ≥ 0.9337). Silvopastures provide an opportunity to improve lamb comfort in the summer.

Browsing by Author "Pent, Gabriel J."

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