Yr Of Grazing Research Articles

Rotational grazing increases purple prairie clover frequency in the rangeland plant communities under semi-arid environment

Purple prairie clover (PPC, Dalea purpurea Vent.) is a grazing tolerant perennial legume with good nutritional quality and is widely distributed across North America. Deferred rotational grazing (DR) and continuous grazing (CG) are the most widespread grazing systems on North American grasslands. We conducted a 10 yr grazing study to assess the effects of environmental factors and grazing on the frequency of PPC in plant communities. The results showed that the frequency of PPC decreased and then increased with increasing precipitation under CG (P < 0.05), while there was no significant change under DR (P > 0.05). Meanwhile, PPC frequency increased with temperature under DR (P < 0.05), but did not change under CG (P > 0.05). Both grazing systems and the number of grazing years had a significant effect on PPC frequency (P < 0.05), and there is no interaction between those two factors (P > 0.05). We found that from 2011 to 2020, the growth rate of PPC population is 18.24% and 11.69% per year under DR and CG grazing, respectively. Moreover, after 10 yr of grazing, the PPC increase in DR was 22.86% higher than that of CG. Thus, selecting the DR grazing system can increase PPC and is an effective practice for coping with environmental changes.

Phenotypic Plasticity and Other Forage Responses to Grazing Management of Ecoturf Rhizoma Peanut

Forage–livestock systems in the southeastern United States are based on N‐fertilized perennial grass pastures, with minimal legume contribution. The legume rhizoma peanut (RP, Arachis glabrata Benth.) can persist and spread in grazed mixtures with C4 grasses, and Ecoturf RP is of particular interest because it is relatively decumbent and may vary its growth habit in response to defoliation management. The objective was to quantify effects of grazing frequency and intensity of Ecoturf on herbage accumulation (HA), canopy characteristics, storage organ mass, and total nonstructural carbohydrate (TNC) concentration. Treatments were the factorial combinations of three levels of regrowth interval (RI; 1, 4, and 7 wk) between grazing events and two levels of post‐grazing stubble height (SH; 4 and 8 cm). For the 4‐cm SH, HA increased from 8.4 to 10.5 Mg ha−1 in 2015 and from 9.8 to 13.6 Mg ha−1 in 2016 as RI decreased from 7 to 1 wk. The effect of RI was less pronounced for the 8‐cm SH. When grazed to a 4‐cm SH, herbage bulk density and post‐grazing leaflet mass increased linearly as RI decreased from 7 to 1 wk in both years. Changes in root‐rhizome mass and TNC pool during 2 yr of grazing were not affected by SH or RI. Ecoturf adapted to frequent, close grazing by increasing herbage bulk density and positioning leaves close to the soil surface, allowing rapid regrowth after defoliation without depleting reserves. Ecoturf is tolerant of a range of grazing strategies, showing promise for use in pastures.

Mixed Stocking by Cattle and Goats for Blackberry Control in Rhizoma Peanut–Grass Pastures

ABSTRACTBlackberry (Rubus fruticosas L.) can be a weed in rhizoma peanut (Arachis glabrata Benth.)–grass pastures. Goats (Capra hircus) have provided effective control of Rubus spp. in other environments, but their efficacy has not been tested in legume‐grass swards in this context. The objective was to evaluate rotational stocking by goats alone or with cattle (Bos spp.) for blackberry control. Treatments stocked at 2.6 animal units (AU) ha−1 included a cattle‐alone control, goats alone, concurrent stocking of cattle and goats, sequential stocking of cattle followed by goats, and sequential stocking of goats followed by cattle. The final treatment was concurrent stocking at a stocking rate of 3.5 AU ha−1. Goats grazed blackberry readily, but cattle avoided it. Blackberry selection was greatest when goats followed cattle sequentially. The blackberry proportion of total biomass increased 10% when cattle grazed alone but was reduced 11% with goats alone and 13% with mixed concurrent grazing at a high stocking rate. Treatments including goats resulted in reductions or smaller increases in blackberry mass than for cattle alone. Goats alone or with cattle resulted in greater removal of blackberry leaf and in reduced height and stem density than cattle alone. Goats reduced the blackberry contribution more than cattle, but it was not eliminated from initially heavily infested pastures across 2 yr of grazing. A greater goat stocking rate or a combination of grazing and mowing may be needed for complete eradication.

Steer Performance, Intake, and Digesta Kinetics of Switchgrass at Three Forage Masses

Management strategies to accommodate switchgrass (Panicum virgatum L.) in production systems have been reported but impact of variation in forage mass (FM) on animal responses and pasture stands are lacking. This 4‐yr study assessed canopy and stand characteristic and steer (Bos taurus) responses when ‘Kanlow’ switchgrass was continuously and variably stocked to produce Short (S) (10–16 cm), Medium (M) (20–26 cm), and Tall (T) (35–41 cm) canopy heights. From April to mid‐July (Period 1) FM for S, M, and T average 818, 2164, and 3294 kg ha−1, respectively. Canopies had similar in vitro organic matter disappearance (IVOMD) (626 g kg−1), but increased in neutral detergent fiber (NDF) from S (645 g kg−1) to T (665 g kg−1). Diets decreased in IVOMD from S (744 g kg−1) to T (706 g kg−1). Digesta kinetics data were not altered and average daily gain was similar among FM (1.11 kg d−1). From mid‐July to late September (Period 2), FM averaged 465, 1282, and 2388 kg ha−1, respectively, for S, M, and T. Whole canopy IVOMD increased from S (484 g kg−1) to T (538 g kg−1), whereas NDF was not altered (696 g kg−1). Steers selected a diet similar in IVOMD (685 g kg−1) and NDF (667 g kg−1) among FM. Estimates of dry matter intake (kg 100−1 kg body weight) increased from S (1.75) to T (2.54). Tiller density decreased from T to S. Continuously stocked switchgrass at 20 to 40 cm remained vegetative with 1279 tillers m−2 after 3 yr of grazing.

Grazing Management Effects on Productivity, Nutritive Value, and Persistence of ‘Tifton 85’ Bermudagrass

‘Tifton 85’ bermudagrass (Cynodon spp.) is an important forage in the southern United States, but its responses to the interaction of grazing frequency and intensity have not been studied. Sward persistence, herbage accumulation, and nutritive value were measured during 3 yr. Treatments were all combinations of three postgraze stubble heights (SH; 8, 16, and 24 cm) and three regrowth intervals (RI; 14, 21, and 28 d). Short SH (8 cm) with long RI (28 d) or tall SH (24 cm) with short RI (14 d) produced greatest herbage accumulation (11–15 Mg ha−1 yr−1). Lowest or nearly lowest herbage accumulation occurred with 14‐d RI and 8‐cm SH or 28‐d RI with 24‐cm SH (7.4–12 Mg ha−1 yr−1). Intermediate levels of RI (21 d) or SH (16 cm) produced consistent herbage accumulation regardless of level of the other factor. Nutritive value was primarily affected by RI, and P (3.1 to 2.8 g kg−1), crude protein (CP; 150 to 108 g kg−1), and in vitro digestible organic matter (IVDOM; 602 to 582 g kg−1) concentrations decreased as RI increased. Organic matter and nutrient mass of storage organs increased with increasing SH, but the 24‐cm SH treatment exhibited greater reduction in percentage cover (∼43% units) than the other SH treatments (∼22% units) after 3 yr of grazing. These data indicate that intermediate levels of SH (16 cm) and RI (21 d) provided relatively high Tifton 85 herbage accumulation and nutritive value while minimizing negative impacts on persistence‐related responses.

Late-Season Targeted Grazing of Yellow Starthistle (Centaurea solstitialis) with Goats in Idaho

AbstractYellow starthistle (Centaurea solstitialis) is an exotic winter annual forb that is aggressively invasive and problematic in much of California, Idaho, Oregon, and Washington. Yellow starthistle control is particularly challenging in canyon rangelands where accessibility limits control options. Our objective was to evaluate the effects of late-season targeted goat grazing on yellow starthistle and nontarget grasses and forbs. A 3-yr grazing study was initiated in 2006 on a 380-ha (939 acres) canyon grassland site infested with yellow starthistle near White Bird, ID. Twenty-four paired plots were established, with each pair including a fenced subplot to exclude grazing and a similar-sized adjacent subplot that was grazed. Density of yellow starthistle plants and seedheads was assessed after grazing of each plot in all 3 yr and before grazing in the second and third years. Canopy cover of yellow starthistle, grasses, and forbs also was measured. Grazed subplots had 58% fewer yellow starthistle plants than the ungrazed controls after grazing was applied and 94% fewer seedheads after 3 yr of grazing. Cover of yellow starthistle did not differ between grazed and ungrazed subplots after grazing in 2006, whereas grazing decreased yellow starthistle cover in 2007 and 2008 by about 75%. Goat grazing had little impact on canopy cover of grasses and resident forbs, with the exception of after grazing in 2007 when there was less forb cover in grazed areas compared with ungrazed areas. Late-season (i.e., July to November) targeted goat grazing appears to be an effective way to reduce yellow starthistle plant densities at landscape scales, which creates a large window of opportunity for grazing treatment and flexibility for land and livestock managers.

Upland Switchgrass Yield, Nutritive Value, and Soil Carbon Changes Under Grazing and Clipping

There have been few evaluations of switchgrass (Panicum virgatum L.) cultivars under multiple harvest managements in the northeastern United States. The objective of this study was to determine the yield, nutritive value, and soil C changes of switchgrass cultivars under grazing and clipping. In 1999, ‘Cave‐in‐Rock’, ‘Trailblazer’, and ‘Shawnee’ switchgrass were established in field plots at Rock Springs, PA, and in pastures in southeastern Pennsylvania. In 2000 and 2001, two‐ and three‐cut treatments were imposed at Rock Springs. At the southeastern Pennsylvania site, pastures were grazed three or four times per year during 2000 to 2004. Forage yield, crude protein (CP), neutral detergent fiber (NDF), and neutral detergent fiber digestibility (NDFD) were determined at each harvest. Soil was analyzed for C and stable C isotopes before planting in 1999 and at the end of the experiments. Cultivars differed slightly in yield and nutritive value. Variation in forage yield was greater among years and management treatments (3300 to 8200 kg ha−1) than among cultivars (5900 to 9400 kg ha−1). Trailblazer suffered from leaf diseases and lodging during wet years. There were no differences among cultivars in soil C. Soil C accumulated in the surface 5 cm of soil after 7 yr at Rock Springs, but soil C did not change after 5 yr of grazing. By the end of the experiments, about 20% of soil C in the surface 5 cm was derived from switchgrass. Cave‐in‐Rock and Shawnee are equally suited and superior to Trailblazer for hay and grazing in Pennsylvania and similar areas in the northeast.

‘Florigraze’ and ‘Arbrook’ Rhizoma Peanut as Pasture for Growing Holstein Heifers

‘Florigraze’ and ‘Arbrook’ are the most widely used cultivars of rhizoma peanut (Arachis glabrata Benth.), but performance of ruminants grazing these cultivars has not been compared. The objective of this study was to determine sward characteristics and performance of Holstein replacement heifers (Bos taurus) on continuously stocked pastures of Florigraze and Arbrook growing on a loamy, siliceous, hyperthermic Grossarenic Paleudult soil. Herbage mass and allowance did not differ between cultivars during 3 yr of grazing and averaged 2840 kg DM ha−1 and 2.25 kg of forage kg−1 of animal live weight, respectively. Percentage of Arbrook in pasture herbage mass decreased from Year 1 (89%) to Year 3 (66%), while percentage of Florigraze remained relatively constant (90 to 87%). Average herbage crude protein (CP) concentration and in vitro organic matter digestibility (IVOMD) were greater in Florigraze than in Arbrook (177 vs. 161 g kg−1 and 705 vs. 661 g kg−1, respectively). Average stocking rate varied little between cultivars, and animal performance was generally similar until Year 3. With a much lower percentage of rhizoma peanut in herbage mass for Arbrook than Florigraze pastures in Year 3, average daily gain (ADG; 701 vs. 516 g) and gain ha−1 (575 vs. 418 kg) were greater for heifers grazing Florigraze than for those grazing Arbrook. Florigraze appears better suited for pasture programs with continuous stocking, primarily because of superior persistence, leading to greater animal performance with time.

Canopy Height Effects on Vaseygrass and Bermudagrass Spread in Limpograss Pastures

Potential grass weeds in limpograss [Hemarthria altissima (Poir.) Stapf & Hubb.] pastures include vaseygrass (Paspalum urvillei Steud) and common bermudagrass [Cynodon dactylon (L.) Pers.]. Grazing management is critical to controlling spread of these grasses and maintaining productive limpograss swards, but competition dynamics among these species have not been evaluated under grazing. The objective of this experiment was to determine the effect of grazed canopy height (20, 40, and 60 cm) of continuously stocked limpograss pastures on changes in frequency of occurrence and ground cover of limpograss, vaseygrass, and common bermudagrass and plant density of vaseygrass. Experimental units were 0.5‐ha pastures replicated four times in a completely randomized design. During the 2 yr of grazing, vaseygrass density decreased in all pastures, changing most for the 20‐cm canopy height and least for the 60‐cm canopy height (4.4 vs. 0.4 plants m−2). Changes in vaseygrass cover followed the same trend as density. In contrast, bermudagrass cover increased by seven percentage units if pastures were grazed to a 20‐cm height, but the increase was less for 40‐ and 60‐cm swards. These data show that continuous stocking of limpograss pastures decreased vaseygrass plant density, especially when canopy height was low; however, common bermudagrass invasion was favored by grazing to 20 cm, potentially compromising limpograss persistence. It is concluded that grazing continuously stocked limpograss pastures to approximately 40 cm is effective in decreasing existing populations of vaseygrass while minimizing invasion by common bermudagrass.

Plant Persistence and Animal Performance for Continuously Stocked Alfalfa Pastures at Three Forage Allowances

Alfalfa (Medicago sativa L.) has not been well suited for pasture because of its intolerance to grazing. 'Alfagraze', a cultivar bred for grazing tolerance, offers potential to use alfalfa as pasture. A 3-yr grazing study was initiated in central Georgia to investigate persistence and animal performance of 'Apollo' and Alfagraze alfalfa at low, medium, and high forage allowance (FA). The FA for this study were targeted at 1000, 2000, and 3000 lb dry matter (DM)/1100 lb animal unit for low, medium, and high FA, respectively. Low FA reduced stand of both cultivars (P < 0.05) after only 1 yr (low = 6.8, medium = 8.2, high = 8.8 plants/sq ft). After 2 yr, high FA paddocks averaged 8.6 plants/sq ft, while medium and low FA had decreased to 5.4 and 4.4 plants/sq ft, respectively. The difference in grazing tolerance between cultivars became evident after 2 yr of grazing, when, averaged across FA, Alfagraze had 7.3 plants/sq ft and Apollo had 5.0 plants/sq ft. After an additional year of continuous stocking, Alfagraze had approximately 150% more plants than Apollo. Persistence differences between cultivars were most evident at low FA. After 2 yr of low FA, Alfagraze had 5.5 and Apollo had 3.3 plants/sq ft. After 3 yr, Alfagraze maintained stands of 5.5 plants/sq ft, while Apollo stands decreased to 1.5 plants/sq ft. Lower FA resulted in greater bermudagrass [Cynodon dactylon (L.) Pers.] encroachment. Lower FA decreased average daily gain (ADG) in yr 1. At low FA, improved persistence of Alfagraze resulted in 0.45 Ib/d higher ADG than Apollo in yr 2. The better grazing-tolerance of Alfagraze alfalfa resulted in longer stand persistence and better animal performance.

Persistence of cool-season grasses under grazing using the mob-grazing technique

Evaluation of grass germplasms for pasture is usually done in trials which are harvested mechanically. This study evaluated the persistence of 13 cool-season grass species and germplasms under 4 yr of grazing in northeast Saskatchewan, using the mob-grazing technique. Thirteen grass germplasms were contained within each paddock, and the paddocks were grazed by large groups of cattle so that all the herbage was consumed evenly in 1–2 d. Three grazing intensities (light, moderate and intense) were established by varying the rest period between grazings. Ground cover declined more rapidly under intense than under light grazing, but no interaction was found between grazing intensity and grass germplasm. The ground cover of the seeded grasses generally declined but at different rates during the trial, giving a significant grass × year interaction. Parkway crested wheatgrass [Agropyron cristatum (L.) Beauv. ssp. pectination (Bieb.) Tzvel.] declined less than Carlton smooth bromegrass (Bromus inermis Leyss.) and the meadow bromegrass (Bromus biebersteinii Roem &amp; Schult.) cultivars. The most rapid stand decline was observed in intermediate wheatgrass [Elytrigia intermedia (Host) Nevski], northern wheatgrass (Elymus lanceoiatus Scribn. &amp; Smith), and hybrid wheatgrass [Elytrigia repens (L.) Nevski × E. spicata (Pursh) D. R. Dewey]. Seeded grasses were replaced mainly by bluegrass (Poa spp.). The results suggest that mob grazing is a useful technique for evaluating new species and germplasms intended for long-term pastures. Key words: Grazing tolerance, temperate grasses, pasture, ground cover, bromegrass, wheatgrass, wildrye, bluegrass

Responses of Kura Clover to Sheep Grazing and Clipping: II. Below‐Ground Morphology, Persistence, and Total Nonstructural Carbohydrates

AbstractBelow‐ground morphology and total nonstructural carbohydrate (TNC) reserve patterns may explain the excellent persistence of kura clover (Trifolium ambiguum M. Bieb.). Our objective was to determine the effects of frequent clipping and sheep (Ovis spp.) grazing on the below‐ground morphology, TNC reserves, and persistence of kura clover. Clipping and sheep grazing experiments were initiated on a 5‐yr‐old stand of ‘Rhizo’ kura clover on a Waukegan silt loam (fine‐silty over sandy, mixed, mesic Typic Hapludoll) and conducted for 3 yr. Crowns, rhizomes, and roots comprised about 25, 45, and 30%, respectively, of the total below‐ground mass sampled to a 15‐cm depth, which averaged 6600 kg ha−1. Primary crowns decreased from 95 to 55 m−2 during 2 yr of grazing, whereas secondary crowns produced by rhizomes averaged 1340 m −2 and dominated aerial shoot production. Crown, rhizome, and root TNC concentrations ranged from 87 to 212, 85 to 248, and 114 to 239 g kg −1 DM, respectively, and followed a common pattern of TNC being lowest in June and increasing linearly to a maximum in the fall. Clipping treatments ranging from three to six cuttings per year had little impact on below‐ground morphology and TNC concentrations, probably because of residual leaf area remaining after clipping. Persistence was excellent under all defoliation treatments. We conclude that established kura clover has an extensive crown‐rhizome‐root system which confers the ability to maintain adequate TNC concentrations for persistence under a range of potential defoliation regimes.

Soil Sampling Procedures for Monitoring Potassium Distribution in Grazed Pastures

AbstractNutrient redistribution in grazed pastures occurs primarily via deposition of excreta by animals. Because this redistribution is generally not uniform, a composite sample of randomly collected soil cores may not reflect the nutrient status of much of the pasture. To address this limitation, zonal soil sampling, with zones determined by distance from shade, water, and supplemental feeders (lounging areas), has been proposed as an alternative sampling strategy. This experiment was conducted to evaluate the potential of zonal soil sampling for monitoring extractable K distribution in grazed pastures. Utility of the zonal approach was evaluated by comparing it with a more rigorous, but less practical transect sampling procedure. Rotationally and continuously stocked bermudagrass [Cynodon dactylon (L.) Pers. ‘Callie’] pastures were used in the study. Ranges of extractable K within a pasture were as great as 13‐fold (14‐181 mg kg−1) after 2 yr of grazing. Extractable K concentration was greatest in the one‐third of the pastures closest to lounging areas regardless of grazing method. Data from zonal soil sampling described this distribution of soil K. Kriged contour maps constructed using data from transect soil sampling supported the conclusions made using zonal sampling. We conclude that zonal soil sampling is a useful and practical tool for describing K redistribution in pastures and for improving the utility of soil test results and fertilizer recommendations for grazed swards.

Soil Potassium Distribution in Grazed K‐31 Tall Fescue Pastures as Affected by Fertilization and Endophytic Fungus Infection Level

AbstractFertilizer requirements of grazed pastures may be influenced by the spatial distribution of nutrients in animal excreta. This experiment was conducted to determine the effect of two levels of fertilization and endophytic fungus (Acremonium coenophialum Morgan‐Jones et Gams) infection of Kentucky‐31 tall fescue (Festucu arundinacea Shreb) on the lateral and vertical distribution of soil K after 3 yr of grazing. Each pasture consisted of 0.7 ha of a Cecil sandy clay loam (clayey, kaolinitic, thermic Typic Hapludult,) and was grazed using the put‐and‐take method. Forage was removed only by grazing. Endophytic fungus levels were 20% (Low endophytic fungus, LE) and 52% (high endophytic fungus HE), and fertilizer rates were 134‐15‐56 kg N‐P‐K (Low fertilizer LF), and 336‐37‐139 kg N‐P‐K ha−1 yr (high fertilizer HF) in a 2 ✕ 2 factorial replicated twice in a randomized block design. Each pasture was divided into 12 zones with each zone sampled separately to a depth of 122 cm before the grazing experiment began and then annually for 3 yr. Potassium did not accumulate in the majority of the pasture area at either fertility level except near the waterer, mineral feeder, and shade. Potassium accumulation rates in this area, determined by linear regression, were 7, 23, 23, and 46 kg K yr‐1 for LELF, LEHF, HELF, and HEHF treatments, respectively. These amounts were equivalent to 18, 24, 59, and 47% of the fertilizer K applied to the 0.7 ha pastures for the LELF, LEHF, HELF, and HEHF treatments, respectively. This accumulation was a result of animal grazing and resting behavior. Much of the K accumulated below 15 cm. Transfer of K by grazing steers to camping zones and subsequent leaching increased with fertility level and endophyte infection level. This redistribution reduces effectiveness of K recycling under grazing, and increases fertilizer K requirements in non‐camping zones.

Spatial Variability of Soil Chemical Properties in Grazed Pastures

AbstractExcretal deposition concentrates nutrients in animal watering and resting areas of pastures, and including these areas in soil sampling may bias fertilizer recommendations. Our objective was to determine the magnitude and extent of nutrient enhancement near a water source in each of two experimental tall fescue (Festuca arundinacea Schreb.) pastures. The rectangular 0.44‐ha pastures were in southcentral Iowa and included three soils: a fine, montmorillonitic, mesic Typic Argiaquoll, a fine‐loamy, mixed, mesic Typic Argiudoll, and a fine, montmorillonitic, mesic Aquic Argiudoll; pH 6.8 to 7.0. Before grazing began in 1976, extractable P (Bray and Kurtz P‐1) and exchangeable K ranged from 3 to 9 and 87 to 156 mg kg−1, respectively, at 0 to 75 mm. After 5 yr of grazing by cattle, soil was sampled at 0 to 75 and 75 to 150 mm on a grid pattern starting at the water source and analyzed for extractable P and exchangeable K, total N, and organic C. Chemical values between the grid points were interpolated by kriging, and contour plots were constructed for each variable. Extractable P and exchangeable K exhibited large accumulations near the water source, with many P and K measurements exceeding 100 and 1000 mg kg−1, respectively. The zone of enhanced P and K levels extended to approximately 10 to 20 m from the water source. Total N declined from 4.2 to 2.1 g kg−1 with progressive distances from the water; however, the range of values was proportionately less than for P and K. Organic C concentrations showed less distinct trends in relation to distance from the water source. The results showed a distinct zone of nutrient enhancement within 20 m of the water source that should be either avoided or sampled separately when sampling pastures for fertilizer recommendations.

Animal Performance on Limpograss‐Aeschynomene and Nitrogen‐Fertilized Limpograss Pastures

AbstractIn vitro digestible organic matter (IVDOM) concentration of ‘Floralta’ limpograss [Hemarthria altissima (Poir.) Stapf et C. E. Hubb.] is high compared to many tropical grasses, but low crude protein (CP) concentration in Floralta may limit animal performance. Aeschynomene (Aeschynomene americana L.) grows well in association with limpograss and may improve animal performance on limpograss‐based pastures. This study compared steer (Bos spp.) average daily gain (ADG), carrying capacity (CC), and gain per hectare from midsummer to early fall on limpograss pastures that were overseeded with aeschynomene (LA) or fertilized with N (LN). Soils were primarily Pomona sands (sandy, siliceous, hyperthermic Ultic Haplaquods). Seasonal ADG (84 d in 1984, and 126 d in 1985 and 1986) was higher for LA than for LN pastures in 1984 (0.69 vs. 0.36 kg), 1985 (0.55 vs. 0.27 kg), and 1986 (0.85 vs. 0.54 kg). Handplucked herbage of aeschynomene had mean CP and IVDOM concentrations of approximately 250 g kg−1 dry matter (DM) and 720 g kg−1 organic matter (OM). Handplucked limpograss CP was marginal for growing steers, averaging 92 and 88 g kg−1 DM in 1985 and 1986, respectively. Mean seasonal CC over the 3 yr of grazing was higher for LN than for LA pastures (2210 vs. 1700 kg liveweight ha−1 d−1). In 1985 and 1986, however, mean seasonal CC did not differ between systems, but from early July to mid‐September LN pastures had higher CC (2240 vs 1540 (1985) and 2450 vs 1930 (1986) kg liveweight ha−1 d−1]. Mean gain per hectare per year was higher for LA than for LN pastures (377 vs. 264 kg) over the 3 yr of grazing. Although LN pastures are easier to manage and have a longer grazing season, these data indicate that gain per animal and gain per hectare can be increased during midsummer through early fall by growing aeschynomene with limpograss.

Animals for Biological Brush Control1

AbstractBiological control of undesirable brush species in rundown or abandoned pastures using animals, particularly goats (Capra hircus), is a viable alternative to chemical and mechanical methods. Vermont experiments on a brushy hill pasture (mesic Aeric Hapalaquepts soil) with cattle (Bos taurus typicus), sheep (Ovis aires), and goats showed that the goat was the best animal for the task. Goats reduced the brush in 1 yr and virtually eliminated it from a badly infested pasture in 2 yr. In contrast, 2 yr of grazing were required before cattle and sheep could decrease brush below the ungrazed control. Unlike cattle and sheep, the goats destroyed small trees and saplings by debarking, were not deterred by thorny vegetation, and browsed much higher by standing on their hind legs. As brush was destroyed, grass increased.

GRAZING SEED FIELD AFTERMATH OF RUSSIAN WILD RYEGRASS, ALTAI WILD RYEGRASS AND GREEN NEEDLEGRASS

The aftermath (residue) from seed fields of Russian wild ryegrass ((RWR) (Elymus junceus Fisch.)), Altai wild ryegrass ((AWR) (Elymus angustus Trin.)), and green needlegrass ((GNG) (Stipa viridula Trin.)) was grazed with cattle to determine the influence of grazing on the subsequent seed yield and to assess the relative value of the aftermath of the three grasses for fall pasture. Removal of the aftermath by grazing resulted in increased seed yields in subsequent years for all three grasses. However, the results were more pronounced for RWR than for either AWR or GNG. Comparative carrying capacities in animal unit days per hectare over the 6-yr period were 83, 156, and 78 for RWR, AWR, and GNG, respectively. Altai wild ryegrass was found to have a deep root system which could utilize a perched water table at 3–4 m deep. Animal weight gains averaged 44, 58, and 44 kg/ha for RWR, AWR, and GNG, respectively. GNG competed poorly with weeds and had largely disappeared after 6 yr of grazing. The nutritive value and digestibility of the forage available to the animals decreased as grazing progressed.