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1
Kuhn, William Robert. "Pest management of billbugs in orchardgrass grown in Virginia". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/76916.
Testo completoAbstract (sommario):
The bluegrass billbug (Sphenophorus parvulus Gyllenhal) and hunting billbug (Sphenophorus venatus vestitus Chittenden) have become important pests of orchardgrass (Dactylis glomerata L.) grown in Virginia, causing 40 - 100% stand losses according to a 2005 survey of over 324 ha (800 ac) of orchardgrass. Their sheltered feeding habits combined with a lack of labeled insecticides for orchardgrass make billbug control extremely difficult for this crop.
Over two seasons, orchardgrass fields were surveyed for paired feeding holes caused by feeding of the billbug spring adult. Simultaneously, barrier pitfall traps, a standard method for determining the presence of billbugs in orchardgrass, were used to trap billbug adults in the fields. A comparison of these methods using a Wilcoxon sign-ranked test found no significant differences in the time when paired feeding holes were first observed in fields and when billbug adults were first trapped, showing that the methods are equally satisfactory for determining the presence of billbugs in orchardgrass.
In addition, temperature data from SkyBit E-Weather® service, which are currently used to alert growers and other interested parties of pertinent billbug activity in orchardgrass, was compared to data from a field-based weather data logger over the two seasons. A comparison of these data showed high coefficients of correlation, indicating a close relationship between these two degree-day collection methods. Therefore, the SkyBit system can continue to be used for the alert system.
A field-border application of Metarhizium anisopliae (Metschnikoff) Sorokin strain F52 (Met-52), an entomopathogenic fungus, was evaluated against billbug adults as they enter orchardgrass fields in the spring. Randomized pairs of treated and untreated plots were placed along the edge of an orchardgrass field in studies over two seasons. Plots were monitored for billbug adults using barrier pitfall traps, and billbug adults were checked for Met-52 infection. The Met-52 proved unsatisfactory for controlling billbugs in this study.
A field efficacy trial was used to evaluate several insecticides and Met-52 against billbug adults in orchardgrass over two seasons. A randomized complete block design, four insecticide treatments and an untreated control were used in each of two trials. Samples from each treatment plot were dissected and checked for billbug life stages and for injury to orchardgrass plants. In one trial, plants in the Sevin XLR Plus® treatment were found to have a significantly higher percentage of injury to the crowns than all other treatments except Mustang Max. No other significant differences were seen in this study.Master of Science in Life Sciences
2
Jones, Gordon B. "Persistence and Productivity of Orchardgrass (Dactylis glomerata L.) in Hay Stands". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/74878.
Testo completoAbstract (sommario):
Persistence of perennial grass crops is essential to their profitable management. Recently, orchardgrass producers in the Mid-Atlantic have reported a reduction in the persistence and regrowth vigor of their swards. The overall objective was to evaluate which factors play a major role in controlling the persistence of orchardgrass harvested for hay in the Mid-Atlantic. A survey of orchardgrass fields, growth chamber experiment, and field experiment were conducted to that end. The objectives were to: (1) assess soil fertility, management practices, disease status, and climate in relation to producer perceived stand persistence rating, orchardgrass biomass, and soil test thresholds in orchardgrass hayfields in 4 states, (2) examine the interactions of high temperature and low cutting height on the physiology and regrowth of orchardgrass in controlled environments, and (3) evaluate yield, composition, and size/density compensation-corrected productivity of orchardgrass and orchardgrass/alfalfa mixtures harvested to four cutting heights over three years. The survey of hayfields indicated that the sward age, soil organic matter, grazing, manure application, and historical average high temperature were main determinants of stand persistence score. In the growth chamber experiment, regrowth was significantly reduced by the 35°C treatment as compared to 20°C. Low cutting height significantly reduced regrowth in the cool temperature treatment, but no effect of cutting height was detected under heat stress. In the field experiment, yields were highest from plots cut to 5 cm, but orchardgrass cover in these plots thinned through the experiment. Tiller size and density measurements indicated that cutting heights of 10 cm or greater were able to achieve and maintain optimal leaf area while productivity was reduced for the 5 cm treatment. Overall, it is apparent that excessively low cutting heights are a major cause of reduced persistence in orchardgrass swards and that high temperature stress will limit regrowth. These factors likely interact with fertility and disease status, and together cause the premature loss of orchardgrass stands. Efforts should be made to communicate the importance of increased cutting height to producers. Breeding of orchardgrass resistant to fungal pathogens and heat stress may be required to sustain an orchardgrass hay industry in the Mid-Atlantic.Ph. D.
3
Moffitt, Deborah L. "Seasonal differences in apparent digestibilities of fescue and orchardgrass/clover pastures by horses". Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/52057.
Testo completoAbstract (sommario):
An experiment was conducted to determine intake and apparent digestibilities of Kentucky 31 tall fescue (Festuca arundinacea schreb.) and orchardgrass/clover (Dactylus glomerata L./Trifolium pratense L.) pastures in different seasons of the year. Three digestion trials were conducted in December, 1985 (winter), May, 1986 (spring) and August, 1986 (summer). Five horses grazed each pasture type. A double marker procedure was used with indigestible neutral detergent fiber (INDF) and Yb as internal and external markers, respectively. Apparent digestibility of dry matter (DM), crude protein (CP), acid detergent fiber (ADF) and neutral detergent fiber (NDF) were determined. Digestibility of orchardgrass/clover components were not different between winter and spring, but were higher (P<.05) in DM, ADF and NDF digestibilities in the summer. Fescue DM and ADF digestibilities were higher (P<.05) in the winter while apparent digestibility of CP was higher (P<.05) in the spring. In summer orchardgrass/clover DM, ADF and NDF digestibilities were higher (P<.05) than fescue. Dry matter intake was not significantly different between forages. Orchardgrass/clover intake was lowest (P<.05) in the winter. Fescue dry matter intake was highest (P<.05) in the summer.Master of Science
4
Shateryan, Djavad. "Evaluation of three cycles of recurrent phenotypic selection for forage yield in orchardgrass and timothy". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26140.
Testo completoAbstract (sommario):
Three cycles of recurrent restricted phenotypic selection (RRPS) were carried out on two cultivars each of timothy (Phleum pratense L.) and orchardgrass (Dactylis glomerata L.). The selections were conducted at the E. A. Lods Agronomy Research Center of Macdonald Campus of McGill University from 1984 to 1988. Individual plant selections were based on dry matter yields of 25 plants. Within each of 16 grids, the five highest yielding genotypes were selected (i.e. 80 genotypes overall) and allowed to interpollinate. Equal weights of seeds from each of the 80 selected plants were mixed in each cycle. Evaluation trials were carried out in both sward and spaced stand from 1989 to 1993 to assess the effectiveness of selection in improving dry matter yield. Several other morphological and physiological characteristics of cycles were recorded to find possible associated changes.Three cycles of RRPS were not effective in increasing forage dry matter yields. The lack of response may be due to a narrow genetic base in the source populations and/or the population size under selection may have been too small, resulting in inbreeding depression. Another explanation for the ineffective selection may be non-random pollination among selected plants. The selection for forage yield produced some minor changes in other characteristics. There was a tendency towards increased plant height and circumference in orchardgrass; however, for timothy, height and circumference were reduced by selection. Cycle 3 of Avon orchardgrass was one day later in maturity and there was also a tendency for later maturity for timothy.
5
Wood, Lauren N. "POST WEANING SUPPLEMENTATION OF APRIL-BORN POLYPAY AND WHITE DORPER LAMBS GRAZING ALFALFA/ORCHARDGRASS PASTURE". UKnowledge, 2016. http://uknowledge.uky.edu/animalsci_etds/60.
Testo completoAbstract (sommario):
The effect of post-weaning supplementation of April-born Polypay and White Dorper lambs grazing alfalfa/orchardgrass pasture during two grazing seasons from June to September was studied. One hundred seventy Polypay and 133 White Dorper lambs were randomly allotted to supplemented (2% BW daily) and unsupplemented groups. It was discovered that Polypay lambs weighed more than White Dorpers at wearning, when the grazing season began, and at the end of the 80 (Year 1) and 85 (Year 2) grazing season (P < 0.01). Polypay lambs gained faster (P < 0.01) than White Dorpers. Supplemented lambs gained faster (P < 0.01) than unsupplemented and Polypays had a greater response to supplementation (P < 0.01) than White Dorpers. Polypays had higher (P < 0.01) fecal egg counts, an indicator of Haemonchus contortus infestation. Supplementation did not have any consistent effect on reducing Haemonchus contortus infestation. Differences in forage characteristics of Polypay and White Dorper lambs did appear. Differences in alfalfa and orchardgrass dry matter, neutral detergent fiber, acid detergent fiber, and crude protein availability were measured by subtracting enter from exit availabilities. The largest decrease of alfalfa components from exit to enter was found with unsupplemented Polypays. No consistent effect was found for orchardgrass components.
6
Potdar, Madhukar Vishwanathrao. "Interference in monocultures and mixtures of orchardgrass (Dactylis glomerata L.) and timothy (Phleum pratense L.)". Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27510.
Testo completoAbstract (sommario):
Interference among plants involves responses of plants to their environment as modified by the presence and/or growth of neighbouring plants. An important theme of research on plant interference is the relationship between plant population density and measures of plant growth or agricultural yield. An experiment on plant interference was performed in which plots of two important forage species, orchardgrass (Dactylis glomerata L.) and timothy (Phleum pratense L.), were grown at different total population densities and mixture proportions. Measures of plant growth and yield were taken at five separate harvests during one growing season.
The analysis of variance indicated that primary and derived measures of growth and yield generally were strongly affected by the three main experimental factors: time, total population density and mixture proportions. Best subset multiple regression analysis, using Mallow's CP criterion, helped to define which experimental factors and interactions were related closely to plant responses. Both of these analytical methods indicated that the main effects of experimental factors were often significant, while interactions among factors were less prominent. The best subset models were different in structure for different response variates, however, indicating that plant responses varied when different measures of growth were considered.
Models were developed which provided an effective description of yield-density responses in monocultures and mixtures when interference was strong. Model parameters were used to compare the relative strengths of intraspecific and interspecific interference in each species. The higher-yielding species, timothy, exerted stronger interference, both within and between species than orchardgrass. Interference was significant early in growth and intensified with increasing population density. The parameters of the yield-density models were also used to assess differential yield responses in the mixtures. Net overyielding occurred in most mixtures because overyielding in timothy was not fully offset by underyielding in orchardgrass. The greatest yield advantage occurred in mixtures containing orchardgrass and timothy in proportions of 2:1.
The dynamics of plant growth were followed using methods of plant growth analysis. Absolute growth rate, relative growth rate, unit leaf rate and crop growth rate were among the growth indices showing strong responses to interference. Interference seemed to disturb the time course of growth in a complex way. Allometric relationships between dry weight per plant and either leaf area per plant or tiller number per plant were also affected by interference. The species differed in their allometric responses, and the relationships between allometry and different treatment factors also varied.Land and Food Systems, Faculty of
Graduate
7
Mundie, Benjamin Scott. "Nutritional Value of Warm- and Cool-Season Grasses for Ruminants". Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/42804.
Testo completoAbstract (sommario):
A metabolism trial was conducted to compare the nutritional value of: 1)â Quickstandâ bermudagrass [Cynodon dactylon (L.) Pers.], 2)caucasian bluestem [Bothriochloa caucasia (Trin.) C.E. Hubb], 3)tall fescue (Festuca arundinacea Schreb.), and 4)orchardgrass (Dactylis glomerata L.). The warm-season grasses (bermudagrass and bluestem) were higher (P < .01) in fiber components than the cool-season grasses (tall fescue and orchardgrass). Bluestem was lower (P < .001) in CP, hemicellulose, and ash, and higher in NDF (P < .001), ADF (P < .001), cellulose (P < .001), and lignin (P < .01) than bermudagrass. The warm-season grasses were lower in the apparent digestibility of DM (P < .001), NDF (P < .01), ADF (P < .05), cellulose (P < .05), and hemicellulose (P < .01) than cool-season grasses. Apparent digestibility of NDF (P < .001), ADF (P < .001), cellulose (P < .01), and hemicellulose (P < .01) was higher for bluestem than bermudagrass. Fescue was higher (P < .001) in apparent digestibility of DM and CP and lower (P < .01) in apparent digestibility of NDF, ADF, cellulose, and hemicellulose than orchardgrass. Lambs fed bluestem had lower (P < .05) N retention than those fed bermudagrass, when expressed as g/d. Lambs fed fescue had higher (P < .001) N retention, than those fed orchardgrass. When expressed as a percent of intake or absorption, N retention values were similar among treatments. The results of this study suggest that cool-season grasses are of higher nutritional value than warm-season grasses.Master of Science
8
Magee, Kelly Jean. "Nitrogen Metabolism of Beef Steers Fed Either Gamagrass or Orchardgrass Hay With or Without A Supplement". NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-04092004-175002/.
Testo completoAbstract (sommario):
This experiment evaluated rumen protein:energy synchronization in steers fed either gamagrass (Tripsacum dactyloides) or orchardgrass (Dactylis glomerata) hays with or without a soybean hull/corn supplement. A N balance trial was conducted to compare the effects of the supplement and hay on N intake, N digestion, and N metabolism. The supplement consisted of 50:50 corn: soybean hulls mix with 50 g molasses per kg of corn: soybean hulls mixture. The supplement contained 11.3% CP, 34.2% NDF, 22.9% ADF, and 0.87 kg was fed at 0830 and 1600 followed by hay offered in two equal portions. Steers had ad libitum access to water and a trace mineralized salt block throughout the study. Hay compositions were 8.3% CP, 71.8% NDF, and 37.8% ADF for gamagrass and were 11.9% CP, 70.5% NDF, and 36.6% ADF for orchardgrass. Steers were individually fed, blocked into two weight groups, and randomly assigned to either gamagrass or orchardgrass hay (4 steers per hay). Within hays, steers were assigned to receive supplement or no supplement in a crossover design. Ad libitum DM intake for each steer was equal to their intake during the last 8d of the 21-d ad libitum period. Steers were then placed in metabolism crates for an 8-d adjustment followed by a 5-d balance trial. During the balance trial, steers were fed 90% of ad libitum intake. Compared with gamagrass, orchardgrass had similar true IVDMD (64.2 vs 62.2%), similar leaf true IVDMD (58.2 vs 63.2%), and similar stem true IVDMD (46.7 vs 51.7%). Effects were significant at P < 0.10. Compared with gamagrass, orchardgrass had a lower ad libitum DM intake (4.62 vs 5.37 kg/d), higher N intake (96.6 vs 81.1 g/d), similar fecal N (36.1 vs 34.5 g/d), higher N digestibility (62.4 vs 57.4 %), similar N retained (27.2 vs 27.7 g/d), and lower digestible DMI (3.20 vs 3.53 kg/d). Compared with no supplement, supplement increased digestible DM intake (3.70 vs 3.03 kg/d), total DM intake (5.87 vs 5.07 kg/d), N intake (96.9 vs 80.8 g/d), fecal N (39.4 vs 31.1 g/d) and N retained (31.7 vs 23.2 g/d). Supplement (1.74 kg/d) decreased hay ad libitum intake by 0.73 kg/d. Supplement decreased, blood urea N, urine urea N and urine urea N as a percentage of urine N more for orchardgrass than for gamagrass. Supplement tended (P < 0.11) to improve N retained as a percentage of N intake or percentage of N digested more for orchardgrass than for gamagrass hay. Blood urea N was reduced (2.21 vs 0.14 mM)more for steers fed orchardgrass hay than for steers fed gamagrass. We believe that the increase in digestible OM intake is due in part to the presence of soybean hulls in the supplement.
9
Canty, Amanda. "Comparison of Nutrient Concentration in Four Fertility Treatments After Poultry Litter Application to Orchardgrass and Sorghum-Sundangrass Hayfield Soils". TopSCHOLAR®, 2002. http://digitalcommons.wku.edu/theses/623.
Testo completoAbstract (sommario):
Field experiments were established in 2001 at the Agricultural Research and Education Complex in Bowling Green, Kentucky to evaluate soil fertility values before and after poultry litter application to orchardgrass and sorghum-sudangrass hayfields. A randomized complete block design was utilized with each treatment being replicated four times. Orchardgrass plots consisted of sixteen 7.6 m rows, 91 m in length and separated by alleys 4.6 m in width. Sorghum-sudangrass plots consisted of sixteen 7.6 m rows, 60.96 m in length and separated by alleys 4.6 m in width. Four separate fertility treatments were utilized: inorganic fertilizer (I), poultry litter applied to meet nitrogen requirements (N), poultry litter applied to meet phosphorous requirements (P), and poultry litter applied to meet phosphorous requirements with a supplemental inorganic fertilizer (NP). In the poultry litter applications, plant available P was estimated to be 80% while N availability was estimated at 50% the first year. Fifteen soil samples were taken in a random, representative manner from each plot of orchardgrass and sorghum-sudangrass prior to litter application and after each harvest. Soil samples were analyzed for pH, N, P, K, Mg, Ca, Fe, Cu, and Zn levels, which were evaluated based upon fertilizer treatment differences Water pH has statistically remained the same thus far, indicating that it is currently not determining nutrient availability among treatments in orchardgrass and sorghum-sudangrass soils. Nitrate concentrations exhibited increases in treatments N and P for orchardgrass soils, while sorghum-sudangrass soils indicated all three treatments N, I, and P were different from each other. There were no differences among treatments for ammonium in orchardgrass soils; however, sorghum-sudangrass soils exhibited a higher concentration in treatments P and I. In both orchardgrass and sorghum-sudangrass soils, treatment N exhibited an increase in phosphate, copper, and zinc concentrations over all other treatments; magnesium and potassium concentrations were highest in treatment N in sorghum-sudangrass hayfield soils. Potassium concentrations were higher in treatments P and N in sorghum-sudangrass soils and the NP and I in orchardgrass soils. Sorghum-sudangrass soils indicated a higher K concentration in treatment N from all other treatments. While orchardgrass soils exhibited no differences in Mg, sorghumsudangrass soils indicated a higher amount in treatment N from all other treatments. Copper and zinc both exhibit a higher concentration in treatment N in comparison to all other treatments in both orchard and sorghum-sudangrass soils.
10
Riley, AnnMarie Christine. "FORAGE QUALITY OF COOL SEASON PERENNIAL GRASS HORSE PASTURES IN THE TRANSITION ZONE". UKnowledge, 2019. https://uknowledge.uky.edu/pss_etds/112.
Testo completoAbstract (sommario):
Cool season perennial grasses are the foundation of equine nutrition in the transition zone. The objective of this study was to evaluate forage quality using ADF, NDF, IVTDMD, CP, WSC, and ESC and changes in vegetative swards seasonally, diurnally, across species (Kentucky bluegrass, tall fescue, orchardgrass, and perennial ryegrass) and cultivar. This study was conducted in 2015 and 2017 and plots were maintained vegetatively with two to four week mowing. Morning and afternoon sample collection occurred monthly during the growing season. Samples were flash frozen; freeze dried, ground, and scanned using Near Infrared Reflectance Spectroscopy (NIRS) to predict forage quality. There was a significant year effect; therefore year was analyzed separately. Generally, ADF and NDF were highest for Kentucky bluegrass (30 and 52%), lowest for perennial ryegrass (25 and 46%), and tall fescue and orchardgrass were inconsistent. Crude protein was variable across species and season, ranging 10 to 25%. ADF and NDF concentrations were higher in the morning; IVTDMD, WSC, and ESC were higher in the afternoon; and CP was similar diurnally. In conclusion, forage quality in vegetative cool season grass pastures was sufficient to meet the nutritional needs of most equines, but varied seasonally, diurnally, across species, and cultivar.
11
Barlow, Rebecca Louise. "Yield, Quality, and Botanical Composition of AUtumn-Accumulated Grass-Legume Mixtures and Digestibility of Ensiled Autumn-Accumulated Orchardgrass and Alfalfa". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9841.
Testo completoAbstract (sommario):
Beef cattle producers in the southeastern US often stockpile forage in late summer to extend the grazing season and reduce feeding costs. Three stockpiled grass-legume mixtures were evaluated for winter grazing. In addition, stockpiled forages were ensiled and evaluated as livestock feed. Four accumulation dates and seven harvest dates were randomized to small plots of tall fescue (Festuca arundinacea Schreb.) -red clover (Trifolium pratense L.), orchardgrass (Dactylis glomerata L.) -red clover, and orchardgrass-alfalfa (Medicago sativa L.). The amount of grass and legume in the fescue-red clover mixture shifted from less than 30% grass and more than 60% legume in October to over 60% grass and less than 10% legume in April. All forage mixtures contained at least 15% CP from November to March. Fescue-red clover was higher in TNC and lower in NDF, ADF and cellulose in January and March than the orchardgrass-legume mixtures. Fescue-red clover was higher in yield than the orchardgrass-legume mixtures from November to February. Delaying stockpiling until September 1 or 15 increased (P <.05) legume content and decreased dead grass content in orchardgrass-clover and orchardgrass-alfalfa. Accumulating growth from September 15 increased percent CP in fescue-red clover and orchardgrass-clover, compared to August 15, and decreased percent NDF in all forage mixtures. Percent IVDMD increased in orchardgrass-clover when stockpiling was delayed until September 15. May yields decreased only in orchardgrass-alfalfa when stockpiling was delayed until September. Orchardgrass stockpiled on August 3 and September 3, and alfalfa stockpiled on September 3 were ensiled alone. Chemical composition of silages was determined after 90 d of fermentation. Silages averaged 16.0% CP and 44.7% NDF. Digestibility of the ensiled stockpiled forages was estimated using acid insoluble ash as a marker with 18 wether lambs. No differences were observed in DM or CP digestibility, but NDF digestibility was lower for alfalfa silage than for orchardgrass silages. All stockpiled grass-legume mixtures provided high quality winter grazing, and all silages were of good quality and digestibility. Fescue-red clover maintained both good quality and higher yield than the other mixtures. Ensiling stockpiled alfalfa and orchard grass provided a method of maintaining CP and digestibility for subsequent feeding.Master of Science
12
Cox, Steven R. "Forage Yield and Quality of Binary Grass-Legume Mixtures of Tall Fescue, Orchardgrass, Meadow Brome, Alfalfa, Birdsfoot Trefoil, and Cicer Milkvetch". DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/4998.
Testo completoAbstract (sommario):
Rising fertilizer prices have led a return to the use of grass-legume mixtures to reduce N costs and improve pasture productivity. The objective of this study was to determine optimal species combinations of binary grass-legume mixtures to improve forage production and pasture nutritive value in irrigated pastures of the Intermountain West. The study was conducted at the Utah State University Intermountain Pature Research Facility near Lewiston, UT. Tall Fescue (TF), Orchardgrass (OG), and meadow brome (MB) were grown with alfalfa (ALF), birdsfoot trefoil (BFTF), and cicer milkvetch (CMV) in legume-grass mixes and monocultures at planting ratios of 25:75, 50:50, 75:25. Grass monocultures were fertilized with 0 (0 N), 67 (67 N), or 134 kg N ha-1 (134 N). Forage was harvested four times each season during 2011-2012. Forage of the mixtures and monocultures from the first and third harvests was analyzed for crude protein (CP) and neutral-detergent fiber (NDF). Average forage production of the unfertilized TF, MB, and OG monocultures was 11.03, 9.76, and 8.10 Mg ha-1, respectively. TF-ALF, OG-ALF, and MB-ALF grass-legume mixes averaged 24.0, 35.0, and 41.0% higher forage production than their respective unfertilized grass monocultures. The grass-legume mixtures with the highest CP were MB-ALF 159, TF-ALF 159, and TF-OG-159 g kg-1 and average 59, 43 and 51% higher than their respective unfertilized grass monocultures. Likewise, the mixtures with the lowest NDF were OG-ALF 453 g kg-1, OG-BFTF 469 g kg-1, and MB-ALF 480 g kg-1. These mixtures had 10, 7, and 18% lower NDF than their respective unfertilized grass monocultures. Individual harvests had similarly higher yields and CP, with lower NDF for the mixtures than the unfertilized grass monocultures. The grass-legume mixture with the 50:50 planting ratio were most productive and had high forage quality. The grass-legume mixtures had similar forage production as the grass monocultures at 134 kg N ha-1. The grass-legume mixtures also had higher CP and lower NDF than the grass monocultures. Cicer milkvetch did not perform well in irrigated pastures. Grass-legume mixtures with ALF and BFTF can be used to replace commercial N while increasing forage nutritive value.
13
Soriano, Felix Diego. "Grazing and Feeding Management of Lactating Dairy Cows". Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36896.
Testo completoAbstract (sommario):
Two studies were conducted during the grazing season of 1997. Study 1 consisted of three Experiments, and the objectives were to compare milk production and composition, body weight change and body condition score, and to determine time patterns of grazing between cows supplemented with different forms and amounts of corn. Also rumen fermentation parameters were measured in cows supplemented with two different types of corn. In study 2, milk yield was measured when grazing pasture was supplemented to lactating Holstein cows fed a typical TMR diet. Predominantly orchardgrass pastures with lesser amounts of white clover and Kentucky bluegrass were grazed during both studies. In Experiment 1, 36 Holstein cows were supplemented either with 6, 6, 6, or 4 kg/d DM of high moisture corn, coarsely ground corn, finely ground corn, or high moisture corn in two equal feedings, respectively. Milk yield was similar (30.3 kg/d) among treatments. Milk protein (2.97%) and MUN (14.7 mg/dl) did not differ among treatments. Body weight change and body condition score change were similar among treatments (23.1 kg and -0.24). During Experiment 2, four rumen-cannulated cows in mid-lactation were supplemented 6 kg/d DM of either coarsely ground corn or high moisture corn in two equal feedings. After the p.m. milking, ruminal pH was measured and rumen fluid samples were collected to determine ammonia N and VFA. While grazing, this was repeated at 0.5, 1, 2, 3,...8 h post-corn feeding (0 h). Ruminal pH was similar for both corn supplements and was lowest (5.9 and 5.8) at 5 and 8 h, respectively. Rumen ammonia N concentrations started to increase approximately 2 h after cows began grazing, reaching maximum levels 5 h later. In Experiment 3, the number of cows grazing, lying, or standing were recorded every half hour, for two consecutive days, while grazing. Cows grazed an average of 6.4 h/d, 4.1 h in the afternoon and 2.3 h in the morning. Similarity in milk production, milk composition, BW change, and BCS between treatments indicates that the quality and availability of pasture permitted equal response regardless of the type or amount of corn supplemented. Fifty four Holstein cows in mid lactation were used in Study 2. Cows were fed either a TMR diet only, or were fed TMR during half of the day (after the a.m. or p.m. milking according to the treatment) and supplemented with grazing pasture during the other half of the day. Milk production was slightly but significantly higher for cows on the TMR treatment (29.1 vs. 28.2 and 27.6). No significant difference between treatments was observed in FCM (27.7 kg/d), and milk fat (3.47) and protein percentage (3.23). While BW change did not differ among treatments (25.7 kg), body condition score increased more in cows fed only a TMR diet (0.14 vs. -0.06 and 0.01). The TMR intake was significantly different between treatments, being highest for cows on the TMR treatment and lowest for cows grazing after the p.m. milking (26.6 vs. 20.3 vs. 17.5 kg/d DM). Income over feed cost differed between treatments, and was approximately 15.3% higher for cows supplemented with high quality pasture during the afternoon compared to cows on TMR. Dairy farmers may obtain economical benefits by practicing this type of management during the grazing season with little effect on milk yield.Master of Science
14
Taylor, Victoria A. "PHYSIOLOGICAL CHANGES ASSOCIATED WITH PREGNANT OR NONPREGNANT MARES GRAZING PASTURES OF ORCHARDGRASS-BLUEGRASS, KENTUCKY 31 TALL FESCUE INFECTED WITH EPICHLOË COENOPHIALA, OR KYFA9821 TALL FESCUE INFECTED WITH THE NOVEL ENDOPHYTE AR584". UKnowledge, 2017. https://uknowledge.uky.edu/gluck_etds/33.
Testo completoAbstract (sommario):
Kentucky 31 tall fescue (KY31) infected with the common toxic endophyte strains of Epichloё coenophiala produces toxic alkaloids that improve plant vigor, but cause numerous adverse effects in grazing animals. Researchers developed a variety of KY31 containing an alternative strain of E. coenophiala, termed novel endophyte (NE). Adverse health effects in mares have not been evaluated.
Experiments in this thesis tested the hypothesis that the NE pasture does not cause adverse effects typically associated with KY31. Specific aims were to: 1) compare forage ergovaline concentrations between KY31 vs NE pastures; 2) evaluate palmar artery diameters in mares grazing KY31, NE, or orchardgrass-bluegrass (OGBG) pastures; 3) determine mare serum prolactin, estradiol, and progesterone concentrations associated with ingesting each pasture type over time; and 4) measure foaling outcomes, including percentage of live foals, foal birth weights, and foal growth rates. In 2015, six nonpregnant mares grazed KY31, six pregnant mares grazed NE and six pregnant mares grazed OGBG pastures. In 2016, eighteen mares were used; six mares grazed each pasture type.
Study results showed that ergovaline did not appear to be produced by NE. Novel endophyte pasture did not have negative effects on palmar artery diameter, reproductive hormones, or foaling outcomes.
15
Mills, Annamaria. "Understanding constraints to cocksfoot (Dactylis glomerata L.) based pasture production". Phd thesis, Lincoln University. Agriculture and Life Sciences Division, 2007. http://theses.lincoln.ac.nz/public/adt-NZLIU20070717.161658/.
Testo completoAbstract (sommario):
This research examined the mechanisms by which temperature, water availability and nitrogen (N) affect the dry matter (DM) yield potential of cocksfoot (Dactylis glomerata L.) dominant pastures. The experiment was a split plot design with main plots of fully irrigated (I) or dryland (D), sub-plots of N fertiliser at 800 kg N/ha in 2003/04; and 1600 kg N/ha in 2004/05 (+N) or 0 kg N/ha (-N). The potential environmental yield of an established 8 year old cocksfoot dominant pasture was 21.9 t DM/ha/y from I+N pastures compared with 9.8 t DM/ha by I-N pastures and 15.1 t DM/ha/y by D+N pastures. The lowest yields were from dryland pastures with no N which produced 7.5 t DM/ha/y in 2003/03 and 5.0 t DM/ha/y in 2004/05.
The effect of seasonal temperatures on the DM production, when periods of water stress were excluded, was quantified using thermal time accumulated above a base temperature of 3°C as 7.0 kg DM/°Cd/ha for N fertilised pastures and 3.3 kg DM/°Cd/ha for pastures with no N.
The 2.5 t DM/ha difference in yields of D-N pastures in 2003/04 and 2004/05 was the result of the duration, extent and timing of the water stress period. In both years the critical limiting deficit (DL) was calculated as 78 mm from the soil moisture deficit in the 0-0.8 m soil layers. Beyond DL yield decreased at a rate of 1.45%/mm in +N and N pastures, relative to fully irrigated control pastures.
Yields of D+N and D-N pastures were similar during periods of water stress with 0.4±0.1 t/DM/ha produced during the rotation ending 30/12/2003. This was less than from either the I-N (1.2 t DM/ha) or I+N (3.5 t DM/ha) pastures due to the reduction in the amount of photosynthetically active radiation intercepted by the canopies of the dryland pastures. However, in the rotation ending 2/5/2004, after autumn rain alleviated drought conditions, yield of the D+N pasture was 2.1 t DM/ha compared with 1.7 t DM/ha by I+N pastures.
The effect of N on yield was described using a nutrition index which showed that as DM yield increased N% in the herbage declined. This is a function of the ratio between metabolic and structural N requirements rather than caused by ontogeny alone. Specific leaf N was determined at two harvests and appeared constant at a given point in time (1.0-1.6 g N/m² leaf). In contrast, specific pseudostem N increased from 0.8-1.0 g N/m² pseudostem at an NNI of 0.4 in N pastures to 2.6-3.0 g N/m² pseudostem at an NNI of 1.2 in the +N pastures.
Differences between the yields of +N and N pastures were caused by differences in radiation use efficiency (RUE) as determined by the linear relationship (R²=0.76) between RUE and the nitrogen nutrition index (NNI).
In this thesis, empirical relationships for the effects of temperature, water availability and N were derived and the physiological mechanisms which underlie these descriptions were identified. These relationships provide clear and simple explanations of the effects of environmental variables on the productivity of cocksfoot based pastures which will enhance understanding of the benefits and limitations of cocksfoot, particularly in dryland farming systems.
16
Fitzsimmons, James P. "Pasture renovation with herbicide suppression of weeds and no-till seeding of orchardgrass". Thesis, 1993. http://hdl.handle.net/1957/35662.
Testo completoAbstract (sommario):
No-till pasture renovation can increase the quality and forage yield of
underproductive pastures. Decreased erosion, lower costs, and less lost
grazing time are advantages of no-till renovation compared to conventional
renovation. Unwanted vegetation is first controlled with herbicides to decrease
competition for introduced orchardgrass. Two field trials were conducted using
a split-plot design to compare three seeding methods and two herbicides. An
Aerway no-till drill, a Tye double disk drill, and broadcast followed by harrowing
were the seeding methods. Paraquat and glyphosate were used to determine
herbicide effect on vegetation control.
Orchardgrass did not adequately survive at either trial site. However,
where some orchardgrass did survive, vegetation control was more important
than seeding method. Competition from annual grasses, many germinating
after herbicides were applied, was the reason for renovation failure. Herbicide
and initial growth for best control.
Yield was doubled in the first harvest by the addition of fertilizer. Early
spring forage production from poor pastures is usually more than adequate, so
the increase from fertilizer is of marginal value unless it is stored for later use.
Yield increase did not carry over to the second harvest when it could be better
utilized. Later application dates would extend yield increases from certain
species if water is available.Graduation date: 1994
17
Fernandez, Jesus Perez. "Rhynchosporium orthosporum in orchardgrass, isolation frequency, colonization, variability, and an evaluation of cultivar resistance". Thesis, 1990. http://hdl.handle.net/1957/38234.
Testo completo
18
Groenenboom, Pierre Sebastiaan. "Investigating reduced rate of nitrogen application and delayed harvest of orchardgrass as a means of reducing the amount and altering the form of nitrogen ingested by lactating dairy cattle". Thesis, 2004. http://hdl.handle.net/2429/15244.
Testo completoAbstract (sommario):
Rations for lactating dairy cattle should supply adequate amounts of rumen undegradable protein without oversupplying rumen degradable protein. As forage grasses can supply too much rumen degradable protein to the ration, it is beneficial to produce forage grasses with higher proportions of rumen undegradable protein while maintaining acceptable yields and fibre levels. Forage grasses have many different types of protein with differing ability to withstand ruminal degradation. Non-protein nitrogen is very rapidly degraded in the rumen whereas true protein consists of a range of proteins, some of which are rapidly degraded while others may escape ruminal degradation. The goal of the present studies was to reduce rumen degradable protein or non-protein nitrogen concentrations in orchardgrass (Dactylus glomerata L. "Benchmark"). One study examined three nitrogen application rates (0, 50, and 100 kg N ha⁻¹) and three growth periods (41, 49, and 59 d) in the spring of 1996 for their effect on fresh orchardgrass yield, fibre content, true protein content, and crude protein content. Samples were incubated in the rumens of ruminallyfistulated Holstein cows to examine dry matter and protein degradation in the rumen. In this study, increasing the growth period of orchardgrass by 15 d proved ineffectual in significantly reducing rumen degradable protein (%crude protein). Increasing nitrogen fertilization rate caused an increase in rumen degradable protein expressed as either %crude protein or as %dry matter without significantly altering rumen undegradable protein (%dry matter). Another study examined three nitrogen application rates (0, 50, and 100 kg N ha⁻¹) and three growth periods ranging from 29 to 59 d after nitrogen fertilization in the spring, early summer and late summer from 1995 to 1997 for their effect on fresh orchardgrass yield, fibre content, true protein content and crude protein content. In all seasons increasing nitrogen fertilization rate caused a significant reduction in the percentage of crude protein that was true protein. In both studies, increasing nitrogen fertilization caused an increase in dry matter and protein yields. It was concluded that incorporating forage grass that has received less nitrogen fertilization into dairy cow rations could reduce ration rumen degradable protein concentrations. However, decreased forage grass yields will require producers to either use additional land for grass production, or to purchase additional forage.