Greater Herbage Accumulation Research Articles

Herbage accumulation, nutritive value, and fatty acid profile of bermudagrass cultivars grown in different latitudes

AbstractThe geographical distribution of bermudagrass cultivars is limited by freezing events (<0°C), commonly associated with higher latitudes in the northern hemisphere. The lipid composition in the plant cell membranes is critical to promote persistence under freezing conditions. This study evaluated herbage accumulation (HA), nutritive value, and lipid biosynthesis of different bermudagrass cultivars in Ona, FL (27°26' N 82°55' W) and Marianna, FL (30o52' N 85o11' W), in 2 years. Treatments were five bermudagrass cultivars (Coastal, Tifton 44, Tifton 85, Jiggs, and Mislevy) distributed in a randomized complete block design with four replicates. HA was greater in Marianna than in Ona for all cultivars (p < 0.05). Mislevy and Jiggs had greater HA in Marianna than the others (p < 0.05), while all cultivars were similar in Ona (p > 0.05). There was no difference between locations or among the cultivars for crude protein and neutral detergent fibre, but bermudagrass cultivars had greater in vitro digestibility of organic matter (IVDOM) in Marianna than in Ona (p < 0.05). The concentration of unsaturated fatty acids increased in the northern latitude (Marianna; p < 0.05). Coastal had greater unsaturated fatty acid concentration than other cultivars (p < 0.05). Geographical location affects HA, IVDOM, and unsaturated fatty acid concentration of bermudagrass cultivars. The unsaturated fatty acid concentration plays a key role in acclimating bermudagrass to different thermal environments. Coastal showed great potential to tolerate chilling stress in Florida. Further studies may be developed to identify promising molecular markers for cold tolerance in bermudagrass.

Black oat as an alternative forage species for the US upper Midwest

AbstractBlack oat (Avena strigosa Schreb.) is a cool‐season annual grass with Mediterranean origin. In contrast to other cool‐season grasses, black oat is more heat tolerant and disease resistant, making it an attractive option for the US upper Midwest, since it can be utilized during summer, when there is decreased productivity of cool‐season forages due to photorespiration. Black oat is recommended for USDA Plant Hardiness Zones 8b–10a, far away from the upper Midwest (zones 2a‐5b). The objective was to evaluate 10 black oat breeding lines (referred to as ‘UF1’ through ‘UF10’) for herbage accumulation, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and in vitro digestible organic matter (IVDOM) concentrations. The experiment was carried out on May–July 2021 and 2022 in Stratford, WI. Triticale (x Triticosecale Wittmack cv. ‘TriCal 342′) and ‘Legend 567′ oat (Avena sativa L.) were included as controls, as well as ‘Ogle’ oat as a regionally recommended cultivar. Herbage accumulation differed by treatment (P = 0.002) and averaged 5900 lb acre−1 among black oat lines, with ‘UF3’ and ‘UF10’ having greater herbage accumulation than oat checks Ogle and Legend 567, and Trical 342 triticale. Crude protein concentration of UF7 and UF3 was 8.5 to 9.5%, respectively. The IVDOM concentrations were above 58% for all black oat. Results indicate certain black oat have the potential to provide forage resources during the early summer in the upper Midwest, but further studies are warranted to evaluate how to best manage this species into cropping or pasture systems in the region.

Release of ‘UF_AlfPers_2015’, a nondormant alfalfa cultivar for the southeastern United States

AbstractThe alfalfa (Medicago sativa L.) cultivar ‘UF_AlfPers_2015’ (Reg. no. CV‐208, PI 702791) was developed by the Agronomy Department, a unit of the Florida Agricultural Experiment Station, University of Florida Institute of Food and Agricultural Sciences (UF‐IFAS), and was released in 2021. The need for high‐yielding and persistent nondormant alfalfa cultivars adapted to the southeastern United States continues to be a factor limiting the adoption and use of alfalfa in the region. A group of 17 alfalfa plants selected from a pasture of ‘Florida 99’ were intercrossed in isolation to produce UF_AlfPers_2015. The experimental line was evaluated for herbage accumulation (HA), persistence, and nutritive value in Florida and other states. UF_AlfPers_2015 had superior HA (20% greater than Florida 99 and 30% than ‘Bulldog 805’ on average) and improved persistence and showed similar nutritive value compared with other cultivars in Florida. UF_AlfPers_2015 had greater HA than ‘Alfagraze 600 RR’ in Gene Autry, OK, and similar HA compared with Bulldog 505 and Bulldog 805 in Gene Autry, OK; Vashti, TX; and Brooksville, MS. UF_AlfPers_2015 is a nondormant (fall dormancy 9) alfalfa cultivar. A US Plant Variety Protection application has been filed, and breeder seed will be maintained by the Agronomy Department of UF‐IFAS.

How does the condition of the pasture in late winter influence the plant and animal responses in the subsequent seasons?

This study aimed to test the hypotheses: (i) the deferred pasture with lower height in late winter has greater herbage accumulation rate (HAR) and better structure, which facilitates the animal selective grazing during the subsequent spring and summer; (ii) the mowed of high pasture in late winter improves the sward structure but decreases its HAR from the spring. Four pasture condition in late winter of Urochloa brizantha cv. Marandu were evaluated: low (24.1 cm and 2,420 kg.ha-1 of DM); low/mowed (25.2 cm and 2,198 kg.ha-1 of DM, mowed at 8.0 cm); high (49.0 cm and 3,837 kg.ha-1 of DM); and high/mowed (50.0 cm and 4,211 kg.ha-1 DM, mowed at 8.0 cm). The highest live leaf blade percentage (LLBP) and the lowest dead stem percentage (DSP) occurred in the mowed pastures. The live stem (LSP) and dead leaf blade percentages of the grazing simulation sample were higher in the high pasture. This same pattern of response occurred for apparent selectivity indices (ASI) of the live leaf blade and live stem. The ASI of the dead leaf blade was greater in the high pasture, intermediate in the mowed pastures, and lower in the low pasture. The ASI of the dead stem was lower in the low pasture. The HAR was higher in low pasture. Our results support the first hypothesis. The mowing of high pasture in late winter improves the sward structure and the animal selective grazing but does not decrease the HAR during spring and summer.

Herbage accumulation and nutritive value of stockpiled limpograss and ‘Tifton 85' bermudagrass

AbstractStockpiling limpograss [Hemarthria altissima (Poir.) Stapf & C.E. Hubb.] may be an option to extend the grazing season and decrease the needs for conserved forage in Florida. This 2‐yr study evaluated herbage accumulation (HA), in vitro digestible organic matter (IVDOM), and crude protein (CP) concentrations of four limpograss entries (‘Floralta’, ‘Gibtuck’, ‘Kenhy’, and Entry 1) and ‘Tifton 85′ bermudagrass [Cynodon spp.] during the growth (May–August) and stockpiling (September–January) periods. During the growth period, treatments were the five grasses. During the stockpiling period, treatments were allocated in a split‐plot arrangement with five grasses (main plot) and four stockpiling periods (5, 10, 15, or 20 wk; subplot). Limpograss and Tifton 85 had similar total HA (mean = 8,150 lb dry matter [DM] acre–1) during the growth period, and Gibtuck had greater HA per harvest than Kenhy and Entry 1 (2,360 vs. 1,940 lb DM acre–1, respectively). Regardless of the stockpiling period, HA was similar among treatments. At 15 wk, HA was maximized in both years, despite being similar to 10 and 20 wk in the first year. In general, limpograss had greater IVDOM and lesser CP concentration than Tifton 85 during growth and stockpiling periods. The decline in IVDOM was slower for stockpiled limpograss than Tifton 85, with greater differences occurring at 15 and 20 wk. Stockpiling limpograss may be an alternative to extend the grazing season in livestock operations, however protein supplementation might be needed to maintain or improve animal performance.

Potential of Urochloa grass hybrids as fodder in the Ethiopian highlands

AbstractUrochloa grasses have shownpromising results for smallholders to cope with feed shortages in tropical Africa. The objective of this study was to evaluate the performance of two Urochloa hybrids, Mulato‐I and Mulato‐II, in the Ethiopian highlands when managed under different plant spacing and harvesting stages. Treatments included three plant spacings for root splits (0.5 by 0.25 m, 0.5 by 0.5 m, and 0.75 by 0.75 m between rows and plants, respectively) and three harvesting stages: (a) 60 d of growth; (b) 90 d of growth corresponding to 50% bloom, and (c) 120 d of growth (corresponding to full bloom). Experimental plots were laid out in a randomized complete block design with three replications, and observations on the same established stands were made in two consecutive years. Varietal differences were observed in plant height (Mulato‐II: 42 cm; Mulato‐I: 72 cm), and herbage accumulation (Mulato‐II: 3.0 Mg dry matter [DM] ha–1; Mulato‐I: 10.6 Mg DM ha–1). Plant spacing also affected the above variables, but year of harvest influenced herbage accumulation. The rate of herbage accumulation tended to be constant, while that of crude protein (CP) declined and fiber concentration increased significantly with advancing maturity. Overall, the decline in quality at full bloom stage appears to be compensated by the greater herbage accumulation, suggesting that farmers can have enough time window to harvest the forages. While Mulato‐I was superior in herbage accumulation, Mulato‐II was found to be better in forage quality. The two grasses have potential to supply good quality forage provided proper management practices are applied.

Evaluation of five bermudagrass cultivars fertigated with swine lagoon effluent

AbstractBermudagrass [Cynodon dactylon (L.) Pers.] hay is an important output from land receiving swine (Sus scrofa) effluent application (also known as spray fields); however, there is limited information about cultivar differences in the upper Southeast United States. Herbage accumulation, nutritive value, tissue nitrate concentration, and stem maggot damage were evaluated for five bermudagrass cultivars (‘Coastal’, ‘Midland 99’, ‘Ozark’, ‘Tifton 44’, and ‘Tifton 85’) fertigated with swine effluent throughout three growing seasons (2016, 2017, and 2018). All cultivars achieved canopy height ≥35 cm by July and cover of 100% by August of year of planting. Based on 3‐yr averages, Tifton 85 (9.3 Mg ha–1) had greater herbage accumulation than cultivars Coastal, Ozark, and Tifton 44 (≈7.9 Mg ha–1), and Midland 99 was intermediate (8.5 Mg ha–1). Bermudagrass stem maggot (Atherigona reversura) damage was consistently lower for Tifton 85 and resulted in larger differences in herbage accumulation in 2017 (11.2 vs. 8.4 Mg ha–1 for Tifton 85 and the other cultivars, respectively). There were moderate differences in crude protein concentration (ranged from 179 to 212 g kg–1) and no difference in total digestible nutrients (622 g kg–1). Tissue nitrate concentrations ranged from 3,433 to 16,168 mg NO3– kg–1. Differences in productivity and nutritive value were moderate among cultivars; however, in areas with potentially high bermudagrass stem maggot damage, greater utilization of Tifton 85, if adapted, is warranted. Hay production from spray fields results in high yields and high nutritive value forage. Frequent nitrate testing, if possible by harvested hay lot, is advised.

Nitrogen's influence on stockpiling of ‘Jesup’ tall fescue cultivars with diverse fungal endophyte presence

AbstractTall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] is used in the southern United States to extend the cow–calf grazing season during autumn and winter by stockpiling. However, livestock producers are reluctant to graze tall fescue because of the toxicity associated with the presence of an endophyte within the grass plant. In this study, the effects of the amount of N fertilizer rate (0, 50, and 100 acre–1), the N source (ammonium nitrate and urea), and the date of N application (September and October) were evaluated for the herbage accumulation (HA) and nutritive value on stockpiled tall fescue. The study was conducted in the autumn of 2007–2009 with six experimental ‘Jesup’ tall fescue cultivars with different endophytic fungal strains: endophyte‐infected wild‐type, endophyte‐free, and infected with the novel endophytes (NE) AR502, AR514, AR542, and AR584. Greater HA was observed with the September N application. Ammonium nitrate was more efficient at increasing HA than urea at both N application rates. Herbage accumulation increased by 56 and 98% at 50 and 100 lb N acre–1 compared with the control. The nutritive value of the stockpiled tall fescue declined as the winter season advanced, despite the source, rate, and timing of fertilizer application. Although the study reported a reduction in nutritive value from November to January, the nutritive value concentrations and estimations are considered optimum for livestock production.

Registration of ‘Mislevy’ bermudagrass

Abstract‘Mislevy’ (Reg. no. CV‐46, PI 693070) bermudagrass [Cynodon dactylon (L.) Pers.] was selected at the University of Florida, and a series of research projects was conducted to evaluate the merit of Mislevy to be released as a new bermudagrass cultivar in Florida. A grazing experiment was conducted in South Florida and clipping trials conducted in South Florida, north‐central Florida, and North Florida. In the grazing trial, Mislevy was compared with Jiggs, World Feeder, and ‘Tifton 85’ bermudagrass, and four stargrass (Cynodon nlemfuensis Vanderyst) cultivars/entries at four grazing frequencies. Mislevy, Jiggs, and Florona had the greatest overall herbage accumulation (HA), but Mislevy had greater HA at late maturity (7 wk). In the clipping trials, Mislevy was compared with Jiggs, Tifton 85, ‘Tifton 44’, ‘Coastal’, Alicia (North Florida only), and ‘Russell’ (North Florida only) bermudagrass. Mislevy and Jiggs had greater spring HA and total HA than the other cultivars/entries in South Florida and North Florida. In South Florida, all cultivars/entries had the presence of Bipolaris spp. in the aboveground forage at the 9‐wk regrowth interval; however, Mislevy and Tifton 44 had greater proportion of green tissue. In north‐central Florida, there was no difference in spring HA among cultivars, and Tifton 85 had greater total annual HA than Mislevy. Mislevy may be a viable option to increase bermudagrass genetic diversity and provide superior spring and annual HA in South Florida.

Herbage accumulation, nutritive value and beef cattle production on marandu palisadegrass pastures in integrated systems

Diversification of monoculture grass pastures may provide opportunity for increased productivity, efficiency, and sustainability of forage-livestock systems. Our objective was to compare herbage accumulation (HA), nutritive value, and animal performance on a grass monoculture control and two alternative systems, all based on ‘Marandu’ palisadegrass [Brachiaria (syn. Urochloa) brizantha (A. Rich.) Stapf] in the Amazon Biome. Alternatives were a crop-livestock system based on soybean [Glycine max (L.) Merr.] and palisadegrass, and a eucalyptus [Eucalyptus urograndis (hybrid of E. grandis W. Hill ex Maiden and E. urophylla S. T. Blake) clone H13]-palisadegrass silvopasture. From July 2017 to May 2018 all experimental units were stocked continuously with beef cattle using a variable stocking rate to maintain a palisadegrass canopy height of 30 cm. The grass monoculture and silvopasture systems had similar HA (13,200 kg dry matter [DM] ha−1) and herbage accumulation rate (HAR; 40 kg DM ha−1 day−1), whereas crop-livestock resulted in greater HA (127%) and HAR (158%) than the other systems. Animal weight gain ha−1 for crop-livestock was 860 kg, 15% greater than for grass monoculture and silvopasture systems (average of 750 kg). Greatest palisadegrass HA and animal performance following 2 years of soybean production support the crop-livestock as an alternative for sustainable intensification. The similar HA and gain ha−1 in the seventh year of the silvopasture and grass monoculture indicates tree-pastures systems need wider arrangements to warrant long-term productivity. The maintenance of soil fertility, appropriate grazing management, and animal nutritional supplementation can greatly improve forage-based systems in the Amazon Biome.

Establishment techniques affect productivity, nutritive value and atmospheric N2 fixation of two sunn hemp cultivars

AbstractNitrogen fertilization is a common practice for sustaining forage production in forage systems in southeastern United States. Warm‐season annual legumes may be an alternative forage to warm‐season perennial grasses that do not require N fertilization. Sunn hemp (Crotalaria juncea L.) is a fast‐growing, warm‐season annual legume native to India and Pakistan. The objective of this 2‐year study was to assess the herbage accumulation (HA), atmospheric N2 fixation (ANF) and nutritive value of sunn hemp. Treatments were the factorial arrangement of two sunn hemp cultivars (“Crescent Sun” and “Blue Leaf”), three seeding rates (17, 28 and 39 kg seed/ha) and seed inoculation (inoculated or non‐inoculated seeds), distributed in a randomized complete block design with four replicates. Crescent sun had greater HA (3,218 vs. 1764 kg DM/ha) and ANF (41 vs. 25 kg N/ha). Blue leaf had greater crude protein (CP) (188 vs. 176 g/kg) and in vitro digestible organic matter (IVDOM) concentrations (564 vs. 531 g/kg) than crescent sun. Non‐inoculated seed had greater CP than inoculated seed, 188 and 177 g/kg, respectively, and inoculation did not affect HA. Intermediate seeding rate (28 kg/ha) decreased HA (2002 kg DM/ha), while HA from high and low seeding rates (17 and 39 kg/ha, respectively) did not differ (2,863 and 2,615 kg DM/ha respectively). Planting non‐inoculated crescent sun at 17 kg/ha seeding rate is a feasible management practice to produce sunn hemp in subtropical regions; however, inoculation should always be recommended for proper establishment.

Grass–Legume Forage Systems Effect on Phosphorus Removal from a Grassland Historically Irrigated with Reclaimed Wastewater

The utilization of reclaimed wastewater is a suitable and sustainable approach to agriculture production in water-scarce regions. However, even though the wastewater is treated to reduce nutrient concentration such as phosphorus, the 10,600 to 14,006 m3 of water applied ha−1 year−1 on grass and alfalfa hay crops in Nevada can lead to soil phosphorus buildup over an extended period. This study evaluated the effectiveness of forage systems (FS) of monoculture grass, monoculture legume, and their mixtures on herbage accumulation, tissue phosphorus concentration, and quantity of phosphorus removed from a grassland under wastewater irrigation. The study was carried out at the Main Station Field laboratory in Reno, Nevada, USA. A total of 23 FS using tall fescue (Schedonorus arundinaceus (Schreb.) Dumort), alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) in monocultures or grass–legume mixtures (25:75, 50:50, and 75:25) based on seeding rate were used. The response variables were herbage accumulation (HA), tissue phosphorus concentration, and phosphorus removal. Forage systems means were considered different P ≤ 0.05. Herbage accumulation, tissue phosphorus concentration, and phosphorus removal differed among FS and year. Herbage accumulation was similar for the grass monocultures (10.5 Mg ha−1; SE = 1.1) and the majority of the grass–legume mixtures (9.0 Mg ha−1; SE = 1.1) but both systems had greater HA than legumes monoculture (4.3 Mg ha−1; SE = 1.1). The legume monocultures of alfalfa and white clover had the greatest phosphorus concentrations (10.9 g kg−1 dry matter; SE = 0.44) among all FS. Total phosphorus removed was least among legume monocultures (34.0 kg P ha−1; SE = 6.2) in this study and generally similar for grass monocultures (67.4 kg P ha−1; SE = 6.2) and grass–legume mixtures of 75:25 (61.7 kg P ha−1; SE = 6.2). Based on the response variables, agronomic, and environmental considerations a grass–legume mixture that includes 75:25 or even a 50:50 seeding rate ratio will be suitable options for phosphorus removal from phosphorus enriched grasslands in semiarid ecosystems that utilized wastewater for irrigation.

Overseeding cool‐season forages on rhizoma peanut fields

AbstractRhizoma peanut (Arachis glabrata Benth.) is an important hay crop in the southern United States. Since rhizoma peanut is a warm‐season perennial legume, it remains dormant during the cool season. Overseeding rhizoma peanut during the cool season could optimize land productivity per unit area throughout the year. However, the effect of overseeding on rhizoma peanut performance in the following growing season is unknown. This study evaluated different combinations of rye (Secale cereale L. ‘FL401’) and/or ryegrass (Lolium multiflorum Lam. ‘Prine’) mixed or not with clovers (Trifolium spp.) overseeded on dormant ‘Florigraze’ rhizoma peanut. Rye–clover mixtures resulted in greater herbage accumulation (6,040 lb ac−1 yr−1) than grass monocultures, clovers, and rye–ryegrass mixtures. However, rye–clover mixtures had similar herbage accumulation to rye–ryegrass–clovers (5,640 lb ac−1 yr−1) and ryegrass–clovers (4,560 lb ac−1 yr−1). Crude protein (CP) concentration in grass was greater for rye and rye–ryegrass (9.8%, for both) than in ryegrass monoculture (8.2%), nonetheless, it was similar to other treatments (9.1%, on average). Ryegrass and ryegrass–clovers resulted in the greater in vitro digestible organic matter (IVDOM) for the grasses (81%, on average) than all other treatments (70%, on average). Overseeding rhizoma peanut did not affect its herbage responses. On average, herbage accumulation, CP, and IVDOM for Florigraze rhizoma peanut in the first harvest following the overseeding treatments were 3,845 lb ac−1, 14.2%, and 75.7%, respectively. Results indicate that overseeding cool‐season grass–legume mixtures would optimize forage production per unit area and improve forage nutritive value without compromising rhizoma peanut herbage responses in the growing season.

Herbage Accumulation, Nutritive Value, and Organic Reserves of Continuously Stocked ‘Ipyporã’ and ‘Mulato II’ Brachiariagrasses

ABSTRACTAlthough Brachiaria spp. grasses are important components of sustainable forage–livestock systems in the Amazon biome, cultivar diversification is needed to reduce risk from pests and diseases. Brachiaria hybrid ‘BRS RB331 Ipyporã’ [B. ruziziensis Germ. & Evrard × B. brizantha (Hochst. ex A. Rich.) Stapf] was released in 2017 as an alternative for intensively managed forage–livestock systems. Our objective was to compare herbage accumulation (HA), nutritive value, and organic reserves of Ipyporã and standard hybrid ‘Mulato II’ (B. ruziziensis × B. brizantha × B. decumbens Stapf) under continuous stocking during 2 yr in the Amazon biome. Treatments were the two cultivars replicated four times in a randomized complete block design, and each experimental unit was 1.5 ha. Pastures of Mulato II presented ∼15% greater HA than Ipyporã (17,360 vs. 14,930 kg dry matter ha−1 yr−1) across the 2 yr, and Mulato II leaf mass was greater than Ipyporã (1440 vs. 1900 kg dry matter ha−1) in the dry season. Both cultivars had greater herbage mass, HA, and herbage bulk density during the rainy season of 2016–2017 compared with 2017–2018 due to a shorter period of water deficit (30 d) and greater rainfall (2147 vs. 1762 mm) in the first than second year. Mulato II herbage crude protein was 10 g kg−1 greater than Ipyporã. In this severe risk region for spittlebug, Mulato II required spittlebug monitoring and control due to occurrence of foliar damage. Although Ipyporã had lesser HA, no spittlebug damage was evident. Thus, Ipyporã is an attractive alternative for diversification of forage‐based livestock systems in the Amazon biome.

Forage and animal production on palisadegrass pastures growing in monoculture or as a component of integrated crop–livestock–forestry systems

AbstractTo meet the global demand for animal protein, sustainable intensification of existing livestock systems may be possible, especially through integration of livestock with crops or forestry. Thus, our objective was to compare forage production and animal performance in grass monoculture and integrated systems in the Brazilian Amazon biome. The four systems were (a) livestock (L) with Marandu palisadegrass {Brachiaria brizantha (Hochst. ex A. Rich.) R. D. Webster} as monoculture, (b) palisadegrass pastures integrated with eucalyptus trees (Eucalyptus urograndis; hybrid of Eucalyptus grandis W. Hill ex Maiden and Eucalyptus urophylla S. T. Blake) arranged in three‐row groves with groves spaced 30 m apart (livestock–forestry; LF), (c) palisadegrass after two years of crops (crop–livestock; CL) and (d) palisadegrass after two years of crops with single rows of eucalyptus trees spaced 37 m apart (crop–livestock–forestry; CLF). From July 2016 to July 2017, all experimental units were continuously stocked using a variable stocking rate. Greater herbage accumulation (HA) occurred in CL and CLF in comparison with L and LF (21,310, 24,050, 19,500 and 18,890 kg DM/ha respectively). The gain per hectare of L, LF and CL (average of 932 kg ha–1) was less than CLF (1,190 kg ha–1). Average daily gain was similar among systems (0.69 kg/day). We conclude that integrated systems can support similar (LF or CL) or greater (CLF) levels of animal production than palisadegrass monocultures while increasing diversity of outputs, thereby providing a greater range of viable systems for livestock production in the Brazilian Amazon biome.

Annual and Perennial Peanut Mixed with ‘Pensacola’ Bahiagrass in North Florida

Fertilization of perennial grass pastures is a major expense in beef cattle operations, and grass pastures may degrade in the absence of N fertilization. Grass–legume mixtures can reduce the demand for N fertilizer use while increasing productivity of the system. Arachis spp. have shown potential for use in association with grasses in the southeastern United States. During 2014, 2015, and 2016, we evaluated one annual peanut species (Arachis hypogaea L. TUFRunner ‘727’) and two perennial peanut species, pintoi peanut (A. pintoi Krap. & W.C. Greg ‘Amarillo’) and rhizoma peanut (A. glabrata Benth. ‘Florigraze’ and germplasm Ecoturf), when planted into previously established ‘Pensacola’ bahiagrass (Paspalum notatum Flügge) sod. Responses measured included herbage accumulation (HA), botanical composition, nutritive value, biological N2 fixation, and belowground root‐rhizome responses. TUFRunner 727 showed reseeding ability, illustrating potential for use as a short‐term forage, but by 2016, its contribution was negligible. In 2016, Ecoturf–bahiagrass had greater HA than unfertilized bahiagrass (4160 and 2710 kg ha−1, respectively), and the Ecoturf contribution to HA was ∼30% in 2016. Average N concentrations for Ecoturf and Florigraze were 25 and 22 g kg−1, respectively, and in vitro digestible organic matter concentration was 700 g kg−1 for both. Pintoi peanut contributed little to mixture HA in the first 2 yr, but it persisted and increased in proportion with time. Over the course of 3 yr, Ecoturf rhizoma peanut performed better than all other entries, exhibiting increasing participation in mixtures each year and the greatest total HA in 2016.

High perennial ryegrass seeding rates do not negatively impact pasture sward persistence

AbstractPoor persistence of perennial ryegrass swards is a common problem; however, there is a lack of long‐term studies to understand the mechanisms associated with poor persistence. This study describes an experiment to test the hypothesis that high ryegrass seeding rates (>18 kg seed per ha) reduce long‐term population persistence because of smaller plant size and poorer survival during the first year after sowing. Four cultivars, representing four functional types of perennial ryegrass, were sown at five seeding rates (equivalent to 6, 12, 18, 24 and 30 kg seed per ha) with white clover in three regions of New Zealand. Swards were monitored for 5 years. No evidence was found to indicate a lack of persistence of ryegrass‐based swards sown at higher seeding rates. During the first year, swards sown at higher seeding rates had greater herbage accumulation (except at the Waikato site), greater ryegrass tiller density and greater ryegrass content. This initial impact of high seeding rates had largely dissipated by the fourth year, resulting in swards with similar annual herbage accumulation, tiller density and botanical composition. Similarly, there were relatively few differences among cultivars for these variables. Although high seeding rates did not negatively impact sward persistence, geographical location did, with strong evidence of ryegrass population decline at the Waikato site for all treatment combinations, some decline in Northland, and stable populations in Canterbury. It is possible that productive perennial ryegrass pastures can only be sustained for 4–5 years in some situations, even when the best ryegrass technology and management practices are used.

Yearling Cattle Performance on Continuously Stocked ‘Tifton 85’ and ‘Florakirk’ Bermudagrass Pastures

Cynodon grasses are a major feed source for livestock in the US Gulf Coast region. Although continuous stocking is widely used for regional perennial grass pastures, there has been limited evaluation of animal performance on continuously stocked bermudagrass [Cynodon dactylon (L.) Pers.]. This 3‐yr experiment compared forage and animal performance on continuously stocked ‘Tifton 85’ (Cynodon spp.) and ‘Florakirk’ bermudagrass pastures using a variable stocking rate during summer (average of 159 d yr−1). Tifton 85 had greater herbage accumulation than Florakirk (average of 13.6 vs. 7.5 Mg ha−1 yr−1, respectively), in part because Florakirk percentage cover declined from 89% at initiation of the experiment to 35% after 3 yr. Change in cover of Tifton 85 over the same period was 93 to 90%. The Tifton 85 forage concentrations of in vitro digestible organic matter was greater than for Florakirk (563 vs. 523 g kg−1, respectively), but yearling cattle average daily gain did not differ between grasses (0.61 kg d−1). Greater herbage accumulation for Tifton 85 resulted in a greater average stocking rate than for Florakirk (6.4 vs. 3.8 head ha−1, respectively) at a similar herbage allowance of approximately 1.0 kg forage dry matter kg−1 animal body weight. Gain ha−1 was greater for cattle grazing on Tifton 85 than on Florakirk (638 vs. 358 kg ha−1, respectively). Tifton 85 was superior to Florakirk bermudagrass under continuous stocking in northern Florida because of its greater herbage accumulation, herbage in vitro digestible organic matter, average stocking rate, animal gain ha−1, and persistence.

Performance of Limpograss Breeding Lines under Various Grazing Management Strategies

Limpograss [Hemarthria altissima (Poir.) Stapf et C.E. Hubb.] is a C4, perennial, stoloniferous grass that is well adapted to poorly drained soils and grows throughout frost‐free periods during winter in southern Florida. Its use has increased rapidly in recent decades, but nearly all area in cultivation is planted with one cultivar, ‘Floralta’. A breeding program was initiated to develop improved alternatives to Floralta, resulting in a group of breeding lines requiring evaluation under grazing. The objective of this research was to evaluate the performance of five limpograss breeding lines (1, 4F, 10, 32, and 34) under combinations of grazing frequency and intensity. During the 2012 and 2013 growing seasons, those lines, plus Floralta, were tested at two pre‐grazing canopy light interception levels (80 and 95%), that triggered the initiation of each grazing event, and two post‐grazing stubble heights (20 and 30 cm). Lines 4F and 10 had greater herbage accumulation, apparent herbage harvested, and persistence than Floralta. Initiation of grazing at 80% canopy light interception resulted in more frequent grazing events, a longer grazing season, shorter pre‐grazing canopy height, greater leaf percentage, less herbage bulk density, and greater herbage crude protein concentration compared with 95% canopy light interception. These data support cultivar release of breeding lines 4F and 10 and suggest that persistence and efficient utilization of limpograss under rotational stocking can likely be achieved by initiating grazing at a pre‐grazing canopy height of ∼60 cm, well before 95% canopy light interception, and by ending grazing at a post‐grazing canopy height of ∼30 cm.

White clover: the forgotten component of high-producing pastures?

The contribution of white clover (Trifolium repens L.) to nitrogen fixation and feed quality in mixed pastures is indisputable, but the benefits of clover inclusion to total herbage accumulation (HA) are less clear. Results from four experiments comparing mixed pastures of white clover–perennial ryegrass (Lolium perenne L.) with perennial ryegrass monocultures are presented. These experiments covered a range of environments (dryland northern New Zealand and irrigated southern New Zealand), management inputs (nitrogen (N) fertiliser rates and defoliation management), and genotypes of ryegrass and white clover. Mixtures resulted in a significantly greater HA than did monocultures in 7 of the 8 years for which data were available; the interaction between pasture type (monoculture or mixture) and N rate was significant in six of those years, with a greater advantage in HA for mixtures under low N rates (mean = 3.08 t DM/ha.year) than under high N rates (mean = 1.54 t DM/ha.year). Two-thirds to four-fifths of the yield advantage under grazing was due to the direct effect of clover contribution (which ranged between 10% and 30% of total annual yield) to HA, most of which accrued in summer. The remainder was due to the capture of additional clover-derived N by the grass component of the mixture, estimated to equate to 50–60 kg N/ha under low N-fertiliser rates and 15–35 kg N/ha under high N rates. The magnitude and consistency of the yield advantages observed here indicates that there are unrealised yield and other benefits not currently being captured in New Zealand dairy production systems, largely because they are negated by the use of high N-fertiliser rates. The agronomic practices required to support clover-rich mixed pastures receiving moderate rates of N fertiliser are well documented and can be applied to help deal with nutrient loss limits required by environmental regulations plus volatility in farm-gate milk prices.