Cool-season Perennial Forage Research Articles

Evaluation of cool-season perennial forage varieties as monocultures and legume–grass binary mixtures under intensive grazing

In Canada, new forage varieties need not undergo grazing trials before registration and sale. To evaluate the effect of grazing, six cool-season species including meadow bromegrass ( Bromus riparius Rehmann), orchardgrass ( Dactylis glomerata L.), sainfoin ( Onobrychis viciifoila Scop.), and three alfalfa varieties ( Medicago sativa L.) were established in monocultures and grass–legume binary mixtures in Saskatchewan, Canada. Forage treatments were randomly established within each of three 3.5 ha paddock replicates. In Year 1, 69 Bos taurus crossbred steers, and in Year 2, 149 steers were homogenously allocated to the three paddocks for the grazing trials. Alfalfa monocultures had the greatest ( p < 0.05) pre-graze forage yields and crude protein content. Leaf area index was greater in alfalfa monocultures than in all other treatments ( p < 0.01). Etiolated growth differed ( p < 0.05) among binary mixtures but not monocultures. Alfalfa monoculture stands were preferred over grass monocultures and most grass–legume mixtures, and sainfoin was avoided relative to alfalfa. Killarney orchardgrass was the least productive and least preferred among forages evaluated. In summary, alfalfa monocultures had greater ( p < 0.05) forage yields and quality than sainfoin monocultures, grass–legume binary mixtures, or grass monocultures.

Response to Waterlogging Stress in Wild and Domesticated Accessions of Timothy (Phleum pratense) and Its Relatives P. alpinum and P. nodosum

Timothy (Phleum pratense) is a cool-season perennial forage grass widely grown for silage and hay production in northern regions. Climate change scenarios predict an increase in extreme weather events with fluctuating periods of high rainfall, requiring new varieties adapted to waterlogging (WL). Wild accessions could serve as germplasm for breeding, and we evaluated the responses of 11 wild and 8 domesticated accessions of timothy, P. nodosum and P. alpinum from different locations in northern Europe. Young plants at tillering stage were exposed to WL for 21 days in a greenhouse, and responses in growth allocation and root anatomy were studied. All accessions produced adventitious roots and changed allocation of growth between shoot and root as a response to WL, but the magnitude of these responses varied among species and among accessions. P. pratense responded less in these traits in response to WL than the other two species. The ability to form aerenchyma in the root cortex in response to WL was found for all species and also varied among species and among accessions, with the highest induction in P. pratense. Interestingly, some accessions were able to maintain and even increase root growth, producing more leaves and tillers, while others showed a reduction in the root system. Shoot dry weight (SDW) was not significantly affected by WL, but some accessions showed different and significant responses in the rate of production of leaves and tillers. Overall correlations between SDW and aerenchyma and between SDW and adventitious root formation were found. This study identified two wild timothy accessions and one wild P. nodosum accession based on shoot and root system growth, aerenchyma formation and having a root anatomy considered to be favorable for WL tolerance. These accessions are interesting genetic resources and candidates for development of climate-resilient timothy varieties.

14 Mitigation Strategies for Heifer Development on ‘KY-31’ Tall Fescue

Abstract Tall fescue (Schedonorus arundinaceus) is the predominant cool-season perennial forage in the Eastern U.S. However, a symbiotic endophyte reduces performance of animals grazing tall fescue. This results in losses of around $2 billion annually. Due to the vasoconstriction caused by the endophyte, a decrease in conception rates among cows and heifers consuming tall fescue has been observed. With rising input costs, it is necessary to explore alternative mitigation strategies these production losses. The objective of this study was to mitigate the toxic effects of ‘KY 31’ tall fescue by limit-grazing cool-season annuals as an alternative to feed supplementation. In January 2022, 48 heifers [14 months of age; 365.9 ± 11.89 kg body weight (BW)] were randomly assigned to tall fescue only, tall fescue with supplemental feed at 1% of BW, tall fescue with limit grazing of cool-season annuals for 24 h per week, and cool-season annuals only. Four animals grazed in each of three replicated paddocks per treatment. Cool-season annual pasture was a mixture of crimson clover (Trifolium incarnatum), annual ryegrass (Lolium multiflorum), and oat (Avena sativa). Body condition scores (BCS), hair coat scores (HCS), and BW were recorded every 30 d. Forage samples were taken for biomass, nutritive value, and ergovaline concentration every 30 d. On April 1, 2022, heifers were artificially inseminated (AI), and conception rates were determined 45 d after AI. Data were analyzed using the Glimmix procedure of SAS 9.4 (SAS Inst, Cary, NC) with α = 0.05. There were no differences among treatments in HCS at any weigh date (P > 0.05). The BCS for all treatments was less in February than January or March (5.6, 6.1, 6.1, respectively; P < 0.0001), but there were no differences among treatments at any sampling date (P > 0.05). Conception rates were not different among treatments (P > 0.10) but averaged 75, 67, 42, and 50% for the continuous-cool season, limit graze, supplemental feed, and tall fescue treatments, respectively. Crude protein (CP) concentrations for the control and limit grazing fescue treatments were greater than the limit grazing cool-season annual treatment, continuous grazing cool-season annual treatment, and the supplemental feed treatment (13.5, 10.7, 10.4, and 8.9%, respectively, (P < 0.012). Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were different among the supplemental treatment when compared with the limit grazing fescue, limit grazing cool-season annual, control, and continuous cool-season annual (48.2 vs 64.7% NDF and 25.8 vs. 37.0% ADF; P < 0.0361). At this time, the results indicate that limit grazing cool-season annual forages may be an advantageous option to mitigate fescue toxicosis in replacement heifers grazing tall fescue pastures in the spring.

Forage yield and profitability of grain‐type intermediate wheatgrass under different harvest schedules

AbstractIntermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & Dewey] (IWG) is a perennial forage grass being domesticated to function as a perennial grain crop. Grain yield of improved, grain‐type IWG cultivars decline by the third year of production and managing aging stands for forage production presents economic opportunities. Limited research is available on the response of second‐ and third‐year grain‐type IWG to different forage harvest schedules. We measured forage yield and nutritive value of grain‐type IWG in the second and third year of production under nine forage harvest schedules varying in the timing of the first harvest (at boot, anthesis, or soft dough stage) and the number of fall harvests (none, one [Sept.], or two [Sept. and Nov.]). As timing of the first harvest was delayed and IWG maturity increased from boot to soft dough, yield increased from 2.4 to 3.7 Mg ha–1 and relative feed value decreased from 113 to 82. Yield at subsequent September and November harvests averaged 30% and 12% of the initial harvest yield, respectively. Total annual forage yield was not affected by the timing of the first harvest but was predictably greater for two or three harvests compared with one harvest; however, additional harvests in September and November decreased net returns. Grain‐type IWG stands harvested in the third year after peak grain production have potential to provide forage similar to common perennial cool season forage grasses. Tradeoffs between forage yield and nutritive value should be considered when selecting the timing of the initial spring forage harvest.

Genome-wide identification, characterization, and expression analysis of the NAC transcription factor family in orchardgrass (Dactylis glomerata L.)

BackgroundOrchardgrass (Dactylis glomerata L.) is one of the most important cool-season perennial forage grasses that is widely cultivated in the world and is highly tolerant to stressful conditions. However, little is known about the mechanisms underlying this tolerance. The NAC (NAM, ATAF1/2, and CUC2) transcription factor family is a large plant-specific gene family that actively participates in plant growth, development, and response to abiotic stress. At present, owing to the absence of genomic information, NAC genes have not been systematically studied in orchardgrass. The recent release of the complete genome sequence of orchardgrass provided a basic platform for the investigation of DgNAC proteins.ResultsUsing the recently released orchardgrass genome database, a total of 108 NAC (DgNAC) genes were identified in the orchardgrass genome database and named based on their chromosomal location. Phylogenetic analysis showed that the DgNAC proteins were distributed in 14 subgroups based on homology with NAC proteins in Arabidopsis, including the orchardgrass-specific subgroup Dg_NAC. Gene structure analysis suggested that the number of exons varied from 1 to 15, and multitudinous DgNAC genes contained three exons. Chromosomal mapping analysis found that the DgNAC genes were unevenly distributed on seven orchardgrass chromosomes. For the gene expression analysis, the expression levels of DgNAC genes in different tissues and floral bud developmental stages were quite different. Quantitative real-time PCR analysis showed distinct expression patterns of 12 DgNAC genes in response to different abiotic stresses. The results from the RNA-seq data revealed that orchardgrass-specific NAC exhibited expression preference or specificity in diverse abiotic stress responses, and the results indicated that these genes may play an important role in the adaptation of orchardgrass under different environments.ConclusionsIn the current study, a comprehensive and systematic genome-wide analysis of the NAC gene family in orchardgrass was first performed. A total of 108 NAC genes were identified in orchardgrass, and the expression of NAC genes during plant growth and floral bud development and response to various abiotic stresses were investigated. These results will be helpful for further functional characteristic descriptions of DgNAC genes and the improvement of orchardgrass in breeding programs.

Runoff nutrient losses from tall fescue pastures varying in endophyte association, fertilization, and harvest management

Tall fescue (<i>Lolium arundinaceum</i> [Schreb.] S.J. Darbysh.) is a widely adopted cool-season perennial forage in the southeastern United States. Historically, tall fescue contained a symbiotic fungal endophyte, <i>Epichloë coenophiala</i>, that produced an ergot alkaloid toxic to livestock. New fescue biotypes have been developed that are endophyte free or include endophytes that produce low-toxicity alkaloids. Ecological implications of these biotypes are not fully understood. We evaluated nutrient runoff quality for three tall fescue biotypes (common, high alkaloid endophyte [wild]; low alkaloid endophyte [novel]; and endophyte free [free]) under two fertilizer sources (broiler litter [BL] and inorganic fertilizer) in grazed systems and a hayed system with inorganic fertilization of endophyte free fescue. The seven treatments were replicated twice on 1 ha paddocks near Watkinsville, Georgia. Grazed paddocks were stocked in September each year with weaned Angus (<i>Bos taurus</i>) heifers (2002 to 2007) and steers (2008 to 2009) at rates of ~3 to 6 head paddock^–1 adjusted every 28 days to maintain 1 to 3 Mg ha^–1 of available forage. Weather conditions varied from very dry to very wet and allowed 15 grazing periods (50 to 198 days). Tall fescue with novel-endophyte association had lower or equal runoff concentrations and loads for inorganic nitrogen (N), total N (TN), ortho-phosphorus (ortho-P), and total P (TP) than fescue with wild- or free-endophyte association (fescue treatment mean concentrations [mg L^–1]: &lt;0.8 inorganic N, &lt;4.0 TN, &lt;3.5 ortho-P and TP; mean loads [kg ha^–1]: &lt;0.08 inorganic N, &lt;0.40 TN, &lt;0.30 ortho-P and TP; all original untransformed data). This indicates increased adoption of novel-endophyte fescue, as previously recommended, presents no additional risk for nutrient losses regardless of fertilization source. Weather variability had impact on assessed variables. Mean total runoff across all paddocks during above average (27.2%) and average (20.6%) monthly rainfall periods were 15.2- and 1.9-fold greater than that from the below average (52.2%) monthly rainfall period. Nutrient loads also were greater: 3.4-fold (TP) to 14.6-fold (ammonium-N). Pollutant loads in the upper quartile were several fold greater than those from the rest of the data. The presence of cattle increased ortho-P load up to 3-fold compared with periods with no cattle.

Selection and Validation of Reference Genes for Quantitative Real-Time PCR in White Clover (Trifolium repens L.) Involved in Five Abiotic Stresses.

White clover (Trifolium repens L.) is a widely cultivated cool-season perennial forage legume in temperate grassland systems. Many studies have analyzed the gene expression in this grass species using quantitative real-time reverse transcription PCR (qRT-PCR). The selection of stable reference genes for qRT-PCR is crucial. However, there was no detailed study on reference genes in different tissues of white clover under various abiotic stress conditions. Herein, 14 candidate reference genes (ACT7, ACT101, TUA1109, TUB, CYP, 60SrRNA, UBQ, E3, GAPDH1, GAPDH2, PP2A, BAM3, SAMDC, and ABC) were selected and analyzed by four programs (GeNorm, NormFinder, BestKeeper, and RefFinder). Samples were taken from two tissues (leaves and roots) under five different abiotic stresses (drought, salt, heat, cold, and heavy metal stress). Our results showed that 60SrRNA and ACT101 were the two top-ranked genes for all samples. Under various experimental conditions, the most stable gene was different; however, SAMDC, UBQ, 60SrRNA, and ACT101 were always top ranked. The most suitable reference genes should be selected according to different plant tissues and growth conditions. Validation of these reference genes by expression analysis of Cyt-Cu/Zn SOD and CAT confirmed their reliability. Our study will benefit the subsequent research of gene function in this species.

Emergence of Puccinia graminis Causing Orchardgrass (Dactylis glomerata) Rust in China

Orchardgrass (Dactylis glomerata L.) is one of the most important cool-season perennial forage grasses around the world and has been widely cultivated in China. Since 2007, a rust was observed on orchardgrass in Chongqing municipality and Sichuan province, China. In May 2018, 85% incidence of the rust was observed in an orchardgrass genetic resources field (29.40 ° N; 105.58 ° E; 296.1 m elevation) in Rongchang district, Chongqing. The disease on orchardgrass is characterized by small, light yellow to yellowish-brown, nearly circular uredia (0.75 to 1.03 × 1.21 to 3.84 mm) surrounded by chlorotic spots, appearing on both sides of leaf, leaf sheath, stem, and inflorescence. Urediniospores were subglobose or ellipsoid monospores, yellow or yellow-brown, 17 to 19 × 22 to 28 μm, with echinulate spines on the surface and three or four germ tube pores distributed equatorially. Telia were rarely observed. Teliospores were smooth, yellowish-brown, club-shaped, twin cells, constricted at the septa, with an obvious stalk, 26 to 41 × 16 to 20 μm. Teliospore wall thicknesses were 1 to 2 μm at the side and 5 to 8 μm at the apex. To support the morphological identification, molecular phylogenetic procedures were applied. Genomic DNA was extracted from urediniospores on infected leaves of orchardgrass. PCR was used to amplify the ITS rDNA region, the 5′ end of the nuclear ribosomal large subunit (28S) and partial beta-tub1 gene sequence (Aime et al. 2018; van der Merwe et al. 2007). A comparison with the GenBank sequences revealed that the ITS, 28S, and beta-tub1 gene sequences were 99.84, 99.70, and 99.38% identical, respectively, to those of Puccinia graminis (GenBank DQ417384.1, HQ412648.1, and HQ317589.1). Homology was also confirmed by analysis of a phylogenetic tree constructed by MEGA7. Representative sequences were deposited in GenBank (accession nos. MH638997.1, MK952783, and MK952781). On the basis of morphology and sequence comparisons, the pathogen was identified as P. graminis (Wang and Zhuang 1998). Rust specimens have been kept in the Forage Specimen Room of Southwest University. Pathogenicity was demonstrated by brushing fresh urediniospores from rusted leaves directly onto the leaves of healthy orchardgrass grown in pots. Control plants were inoculated with sterile water. All pots were kept in a plant growth chamber (20°C, 100% relative humidity) for 24 h and left under glasshouse conditions. Initial symptoms of single chlorotic flecks appeared 4 to 5 days after inoculation. On the seventh day, the host epidermis began to bulge, and within 2 weeks, the epidermis ruptured and showed yellow to brown uredia. Control plants remained symptomless. The rust fungus P. graminis is an important pathogen of orchardgrass, which has been found in 30 countries in the world (Farr and Rossman 2019). However, this is the first report of this fungus causing rust disease on orchardgrass in China. It is anticipated that plants would eventually die under heavy infection, so this fungus potentially could pose a significant threat to local orchardgrass production.

Animal performance and environmental efficiency of cool- and warm-season annual grazing systems.

Annual forage crops can provide short-term grazing between crop rotations or can be interseeded into perennial pastures to increase forage quality and productivity. They also provide an opportunity to increase the economic and environmental sustainability of grazing systems. Cool-season annual forage crops provide high-quality, abundant forage biomass when forage availability from perennial forage species is lacking, reducing the need for stored feeds during the winter months. For example, ADG of 1.5 kg have been reported using small grains alone and in mixtures with annual ryegrass (Lolium multiflorum Lam.) while maintaining an average stocking rate of 3.5 animals/ha. No-till (NT) establishment has been shown to be as effective as conventional tillage for establishing small grain pastures. Stocker performance during the fall was not affected by tillage treatment, but during the spring grazeout, BW gain per hectare was 8% greater in NT pastures. An in vitro study showed that daily production of CH4 was 84% lower, respectively, in turnip (Brassica rapa L.) and rapeseed (B. napus L.) diets compared with annual ryegrass. Warm-season annuals are frequently used during the summer forage slump when perennial pasture growth and quality are reduced. Research has shown that brown mid-rib sorghum × sudangrass (BMR SSG; Sorghum bicolor L. × S. arundinaceous Desv.) and pearl millet (PM; Pennisteum glaucum L.R. Br.) with crabgrass (Digitaria sanguinalis (L.) Scop.) tended to have greater ADG (0.98 kg) than sorghum × sudangrass or peal millet alone (0.85 kg). However, non-BMR and BMR SSG tended to have greater gains per hectare than PM or PM + crabgrass (246, 226, 181, and 188 kg/ha, respectively). Feeding of brown mid-rib sorghum × sudangrass reduced daily production of CH4 and CH4 per gram of NDF fed by 66% and 50%, respectively, compared with a perennial cool-season forage in continuous culture. Cool- and warm-season annual pastures not only provide increased animal gains, but also increase soil cover and in vitro data suggest that annual forages (i.e., brassicas and warm-season annual grasses) decrease enteric CH4 emissions. Establishment method, grazing management, and weather conditions all play important roles in the productivity and environmental impact of these systems. A more complete life cycle analysis is needed to better characterize how management and climatic conditions impact the long-term economic and environmental sustainability of grazing annuals.

Effects of endophyte-infected and non-infected tall fescue residues on aggregate stability in four texturally different soils

Fungal endophyte (Epichloë coenophiala) usually infects cool-season perennial forage grasses and enhances host plant resistance to biotic and abiotic stresses and, by potentially altering the litter quality and decomposition rate, can affect soil properties. Aggregate stability, as an important determinant of plant root growth and soil quality, may be affected by the endophyte status of plant residues. In this study, the effects of endophyte-infected (E+) and endophyte-free (E−) tall fescue residues (0%, 1% and 2%) on soil organic carbon (SOC), basal soil respiration (BSR) and aggregate stability were investigated in four texturally different soils in the laboratory. The aggregate stability indices were determined by the high energy moisture characteristic (HEMC) method. Moist soil samples were thoroughly mixed with either E+ or E− tall fescue residues before being incubated at 25°C. During the 2-month incubation period, the amended soil samples were subjected to ten wetting and drying cycles, after which soil properties were measured. The results indicated that SOC and aggregate stability were higher and that BSR was lower in the finer-textured soils. Furthermore, an increase in the application rate of plant residues significantly increased SOC, BSR and aggregate stability. Treating the soils with E+ tall fescue residues increased SOC and aggregate stability (i.e., stability ratio, SR, a dimensionless index defined as the ratio of the structural index for the fast wetting to the structural index for the slow wetting), and significantly decreased BSR due to the toxic effects of phenolic compounds on soil microbial communities and changes in the litter chemical quality. The interactive effect of soil type and endophyte status on the SOC and BSR values was significant but no clear trend was observed. Our findings indicated that tall fescue residues (especially E+ ones) can improve soil physical quality due to increased SOC storage and greater aggregate stability. Therefore, these plants have great potential for use in grassland reclamation and soil conservation plans in semi-arid pasture and agricultural lands.

Plant drought survival under climate change and strategies to improve perennial grasses. A review

The three cool-season perennial forage grasses cocksfoot/orchardgrass, Dactylis glomerata L., tall fescue, Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh., and phalaris/harding grass, Phalaris aquatica L., are of major economic and ecological importance in regions with summer-dry environments. This review considers the constraints that these species are likely to experience under current and predicted increase of droughts due to climate change scenarios in south-eastern Australia, the southern Great Plains of USA and the Western Mediterranean Basin. The review identifies research required to maximise the development and use of C3 cool-season grasses with enhanced resilience to drought while considering the concern of some regulators that these grasses may be potential weeds. The state of knowledge of factors influencing plant drought survival and therefore recovery after stress and long-term persistence is discussed in the light of adaptive strategies. The major research needs identified to enhance traits conferring drought survival include (1) increasing the depth and density of grass root systems to strengthen dehydration avoidance; (2) exploring the biochemical, molecular and hydraulic bases of dehydration tolerance and improving techniques to measure this trait; (3) breaking the trade-off between summer dormancy and forage yield potential and improving understanding of environmental, biochemical and genetic controls over summer dormancy; (4) identifying non-toxic endophyte strains compatible with summer-dormant cultivars of tall fescue to enhance drought survival; and (5) enhancing seed production capability of new cultivars as well as the development of agronomic management packages for promoting stable mixtures combining perennial grasses and legumes. The weed potential of newly introduced summer-dormant cultivars is concluded to be minor. The research directions proposed here should improve pasture grass resilience and forage crop sustainability in Mediterranean and temperate summer-dry environments under the future drier and warmer conditions associated with climate change.

Orchardgrass die‐off: How harvest management and heat stress may be reducing the persistence of orchardgrass hay stands

Orchardgrass die‐off: How harvest management and heat stress may be reducing the persistence of orchardgrass hay stands

Competition and Survival of Perennial Cool-Season Grass Forages Seeded with Winter Wheat in the Southern Great Plains

ABSTRACT Domestic wheat is the standard winter and spring forage of the Southern Great Plains forage-livestock production system; however, cool-season perennial forage grasses can also become an integral component of this grazing system for livestock producers. Typically, following a mid-September sowing date, only 30–40 growing days are available for cool-season grass establishment. As a consequence, a one year growing season, without livestock grazing pressures, is necessary to provide good stand establishment of the perennial cool-season species. The opposite is true for the case where cool-season annuals like winter wheat or rye can be grazed fairly heavily following a period of stand establishment. The inability of a livestock producer to heavily graze a newly sown perennial cool-season grass forage pasture provides not only a loss of land resources for grazing, but limits the sites where a cattleman can sow pasture to cool-season species and continue to graze his livestock. This study was conducted to determine if perennial cool-season grass forages could compete and become established when inter-seeded with winter wheat as a companion species. Stand counts were performed on each three replicate plots of eighty-two perennial cool-season cultivars and experimental germplasms to determine stand establishment and seedling survival rates. Depending on the species, stand counts of plants per m2 obtained in the fall of 2001 ranged from 0, with no survival, to a value of 40, which indicates a 100%, fully established stand. Results from this study indicate that crested wheatgrass, tall wheatgrass, intermediate wheatgrass, smooth bromegrass and western wheatgrass, when inter-seeded and under competition with winter wheat, can be successfully established and provide grazing resources for livestock producers in the Southern Plains during the first year of sowing.

Bermudagrass–White Clover–Bluegrass Sward Production and Botanical Dynamics

Cool-season forages dominate pastures in the Appalachian region where midsummer weather conditions often depress productivity. Warm-season forages can buffer variation in available herbage, but land resources may limit the area dedicated to special-use crops. A replicated field plot experiment was conducted for 3 yr (1995–1997) in a bermudagrass (Cynodon dactylon L.) stand oversown with Kentucky bluegrass (Poa pratensis L.) and white clover (Trifolium repens L.) to determine the influence of defoliation on productivity, nutritive value, and botanical dynamics of the mixture. Botanical composition changed with defoliation and varied among years. Bermudagrass comprised as much as 55% of the sward in mid- and late-season 1995. By 1997, the proportion was similar to other grasses and rarely exceeded 20%. Maximum instantaneous growth rates occurred later in the growing season in 1995 when bermudagrass was a dominant sward component compared with subsequent years when bermudagrass was <10% of the sward. Rates in 1995 were greatest for swards clipped at 6-wk intervals (70 kg ha−1 d−1) or when 20-cm tall and least when clipped at 2-wk intervals (33 kg ha−1 d−1) and at 10-cm height (45 kg ha−1 d−1). The trend was reversed by 1997 when sward composition shifted away from bermudagrass to cool-season grasses and white clover. Yields were greatest when cool-season species dominated the sward. Creating a self-regulating mixture of warm- and cool-season perennial forages may be a means of achieving some stability in sward productivity and might be useful where wide fluctuations in growing conditions occur among years.

Repeated measures vs. repeated plantings in perennial forage grass trials : an empirical analysis of precision and accuracy

Cultivar evaluations of perennial cool-season forage grasses are an integral part of both breeding and extension programs. There is some doubt that a single trial will result in an accurate representation of cultivar means or rankings, even for a single location. The objective of this study was to quantify the additional precision and accuracy accrued in perennial cool-season forage grass cultivar evaluations resulting from collecting data on additional years of a single planting vs. repeated plantings. The study used data on forage yield, maturity, crown rust reaction (caused by Puccinia coronata Corda), and ground cover of 20 trials of orchardgrass (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.), timothy (Phleum pratense L.), and ryegrass [perennial (Lolium perenne L.) and intermediate (L. hybridum Hausskn.) ryegrasses and festulolium (Festulolium braunii K.A.)]. The study was conducted at Arlington, WI between 1981 and 1991. Common cultivars in pairs of trials, planted in adjacent fields in consecutive years, were analyzed by analysis of variance. Seven hypothetical cultivar evaluation schemes were created, involving various numbers of harvest years of one or two plantings made in consecutive years. Precision of each scheme was measured by the predicted standard error of a cultivar mean (SECM); accuracy was measured by the correlation between cultivar ranks of a scheme with cultivar ranks from means over all 3 years of both plantings. In most cases, there were dramatic reductions in SECM associated with use of a second planting, regardless of the number of harvest years per planting. Forage yield was the only variable for which there was almost no decrease in SECM due to additional harvest years per planting. Rank correlation coefficients for forage yield were high (r ≥ 0.86) for timothy regardless of the evaluation scheme, but increased linearly with additional harvest years for the other three species. For maturity, rust reaction, and ground cover, most rank correlations were greater than 0.9, suggesting a reasonably accurate ranking for all schemes. Because of this and the importance of forage yield per se, the accuracy and precision of forage yield is the primary consideration. An evaluation scheme of two plantings and 3 harvest years for the first planting plus 2 harvest years for the second planting was recommended for this location.

Plant Vigor and Yield of Perennial Cool-Season Forage Crops When Summer Planting Is Delayed

The Cooperative Extension Service in most states recommends dates, in the late-summer or early-fall, when perennial coolseason forage crops should be planted. Planting after the recommended date generally results in less than optimum stand vigor and yield. For many reasons, farmers may wish to plant perennial forages after the recommended date. The objective of this research was to evaluate the performance of forages planted after the recommended latest date. Three perennial cool-season forage legume and grass species were planted on various dates during August, September, and October in 1991 and 1992 at two locations in Pennsylvania. Development and yield of plants was monitored for 1 year after planting. Plant height in lateNovember and percentage ground cover in the spring decreased as planting was delayed after 1 August. Each day planting was delayed after 1 August, total DM yield the following year declined by an average of 158 and 116 lb/acre for alfalfa (Medicago sativa L.), 105 and 71 lb/acre for red clover (Trifolium pratense L.), 76 and 28 lb/acre for birdsfoot trefoil (Lotus corniculatus L.), and 120 and 63 lb/acre for reed canarygrass (Phalaris arundinacea L.) in central and southern Pennsylvania, respectively. Orchardgrass (Dactylis glomerata L.) yields did not decrease at either location when planting was delayed from early- to mid-August. After mid-August, however, orchardgrass yield declined by an average of 92 lb/acre for each day planting was delayed. Perennial ryegrass (Lolium perenne L.) yields increased by over 1.0 ton/acre when planting was delayed from early-August to late-August. Daily delays in planting perennial ryegrass after late-August resulted in average yield reductions of 134 lb/acre. In general, planting perennial cool-season forage crops after 5 September in central and 10 October in southern regions of Pennsylvania resulted in ground cover judged too low for conservation purposes and produced yields that were too low for practical forage harvesting. Accumulated growing degree days (GDD, base 32°F) from 5 September and 10 October until the first killing frost (temperature ≤ 27°F) were approximately 1000 and 230, respectively

Metabolizable Protein of Summer Annuals for Growing Calves

Two trials were conducted to determine and evaluate the rumen degradable and escape protein (EP) value of two summer annuals for yearling cattle. In Trial 1,120 heifers (Bos taurus) (530 lb), arranged in a completely randomized design, were supplemented with 0, 0.25, 0.40, or 0.55 lb crude protein (CP)/d supplied by corn gluten meal:blood meal (CGM:BM) replacing a corn starch:molasses control, keeping the supplements equivalent in energy. Heifers grazing ‘Piper’ sudangrass [Sorghum bicolor (L.) Moench] (70 d) showed a negative linear (P < 0.02) response to supplemental protein and quadratic (P < 0.10) response (1.41,1.54,1.32, and 1.14 lb/d gain, respectively). Heifers grazing Northrup King ‘Millex’ pearl millet [Pennisetum americanum (L.) Leeke] (55 d) showed a cubic (P < 0.05) response (1.01, 1.23, 1.08, 1.25 lb/d gain, respectively) which tended to be linear (P = 0.13). Cattle on pearl millet responded to supplemental protein while cattle on sudangrass did not, which is supported by high EP values of sudangrass extrusa. In Trial 2, 60 Angus heifers and 60 Angus steers (600 lb) grazing sudangrass (56 d) were allotted to (i) molasses (ii) corn starch (iii) CGM:BM at 0.25 lb CP/d (iv) corn starch and CGM:BM at 0.25 lb CP/d, or (v) CGM:BM at 0.50 lb CP/d. All five treatments contained the same amount of molasses, and corn starch provided energy equal to CGM:BM. Supplemental protein improved gains (P = 0.10) (1.10,0.99,1.14 lb/d, respectively) over the molasses control (0.84 lb/d) but did not increase gains over the corn starch (1.17 lb/d). The lack of response to supplemental EP above the corn starch is again supported by high EP values of the sudangrass extrusa. Research QuestionSummer annuals can provide alternate pastures for grazing yearling cattle during summer slump periods of cool season perennial forages. They are also an alternative crop for cultivated land less suitable (or less profitable) for other cropping systems. Summer annuals can be grazed more intensely than perennial forages because perennial stands must be maintained for subsequent years. For the summer annuals to be a viable alternative, however, they should provide high gains per acre. This can be achieved if digestibility and protein levels are adequate. The objective of Trial 1 (1989) was to determine the escape protein value of sudangrass and pearl millet for growing calves. The objective of Trial 2 (1990) was to further evaluate the metabolizable protein value of sudangrass. Literature SummaryMetabolizable protein is the combination of microbial protein synthesized from rumen degradable protein and escape protein (not degraded in the rumen and used directly by the animal). Metabolizable protein should be adequate for optimum cattle growth before the forage is a viable option. The protein requirement of rapidly growing ruminants is not met by microbial protein synthesis alone. Dietary escape protein has increased performance in growing cattle when energy and ammonia were not limiting microbial protein synthesis. The metabolizable protein value of sudangrass and pearl millet for growing calves has not been evaluated. Study DescriptionIn Trial 1, 60 heifers grazed ‘Piper’ sudangrass (70 d) and 60 heifers grazed Northrup King ‘Millex’ pearl millet (55 d). Treatments: Corn starch:molasses control at 0 lb crude protein (CP)/d Corn gluten meal:blood meal (CGM:BM) at 0.25 lb CP/d CGM:BM at 0.40 lb CP/d CGM:BM at 0.55 lb CP/d In Trial 2, 60 heifers and 60 steers grazed Piper sudangrass (56 d). Treatments: Molasses Corn starch CGM:BM at 0.25 lb CP/d Corn starch and CGM:BM at 0.25 lb CP/d CGM:BM at 0.50 lb CP/d All five treatments contained the same amount of molasses; and corn starch provided energy equivalent to that of CGM:BM. Applied QuestionDid supplemental escape protein increase gains of cattle grazing sudangrass or pearl millet? Supplemental escape protein did not increase gains of cattle grazing sudangrass. The cattle primarily ate leaves which were highly digested. The sudangrass leaves appeared to supply enough escape protein. Supplemental escape protein slightly increased gains of cattle grazing pearl millet. The pearl millet leaves were also highly digested but did not supply adequate escape protein; however, supplementation might not improve gains enough to be economical. Is metabolizable protein limiting in sudangrass? The lack of response to supplemental protein above the corn starch control and the adequate levels of rumen ammonia measured, suggests metabolizable protein is not limiting for growing calves.

Yield and Persistence of Tall Fescue in the Southeastern Coastal Plain after Removal of Its Endophyte

AbstractThe coastal plain of the southeastern USA lacks a dependable perennial cool season forage crop, but tall fescue (Festuca arundinacea Schreb.) germplasms have been developed which show greater persistence and yield than currently marketed cultivars in this region. Since these germplasms were found to be infected with the tall fescue endophyte (Acremonium coenophialum Morgan‐Jones and Gams), the contribution of the endophyte to their performance was unknown. The objective of this study was to compare yield and stand survival of endophyte‐infected (El) and endophyte‐free (EF) (achieved by removal of its endophyte) versions of four persistent germplasms (GA‐5, GA‐Jesup, GA‐Jesup Improved, and GA‐Ecotype KY31) in clipped small plots at three locations in Georgia (Americus and Tifton in the coastal plain and Watkinsville located in the fescue growing area of the southern piedmont region) for a 3‐yr period. The El version of each germplasm showed greater stand survival and yield than its EF version at Americus and Tifton, but no differences were recorded for infection status for the same parameters at Watkinsville. These findings indicate that endophyte removal greatly reduces the ecological fitness of tall fescue by possibly allowing less tolerance to summer drought. Presently, only El tall fescue can be dependably recommended for perennial pasture in the southeastern coastal plain.

Yield Testing Cool‐Season Forage Grasses in Pure Stands vs. Binary Mixtures with Alfalfa1

Cool season perennial forage grasses are grown in pure stands and in mixtures with other grasses or legumes. Differential environmental and competitive effects between pure and mixed stands may cause interactions with cultivars or breeding lines. Our objective was to compare the productivity of cultivars of four cool‐season perennial forage grasses in pure stands and binary mixtures with alfalfa (Medicago sativa L.). Cultivars of orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), tall fescue (Festuca arundinacea Schreb), and timothy (Phleum pratense L.) were grown in replicated trials in pure stands and binary mixtures with alfalfa at five Wisconsin locations for up to three seasons. Differences among cultivars were significant for 12 of 38 species‐environment combinations in pure stands and eight in mixed stands. Coefficients of variation were slightly higher for pure stands, while the square root of broad sense heritability showed no consistent differences between stand types. Rank correlations for cultivar yield between the two stand types were generally nonsignificant for all species, except timothy. Both stand types were about equally susceptible to cultivar ✕ environment interaction, except cultivar ✕ year interaction for timothy. We concluded that additional replication is necessary to obtain the desired level of precision in forage yield trials. With the possible exception of timothy, recommendations of superior grass cultivars in alfalfa mixtures should be based on mixed stand performance.