This thesis gives (1) a review of literature on pastures and hogging off crops, (2) a description of the farming system of the Peanut Section of Southeastern Virginia as it relates to swine production, and (3) an outline of procedure for two experiments dealing with swine production problems in the Peanut Section. / M.S.

A grazing trial was conducted to determine the relative value of three mixed-forage pastures, alfalfa-orchardgrass, bluegrass-white clover, and fescue-red clover. Three steers, three heifers and one esophageally cannulated steer were randomly assigned to each pasture treatment. Chemical composition, digestibility, voluntary intake, and selectivity of the forages were determined through use of esophageally cannulated steers and a rare earth marker (ytterbium). Forage intake appears to be most closely related to DM digestibility and content of the NDF and ADF fiber fractions. Some degree of forage selectivity was observed, although the specific species selected for and determinants of selectivity were not apparent. From the data obtained on levels of intake, digestibility and chemical composition, alfalfa-orchardgrass and bluegrass-white clover offer the highest quality forage of the three compared during the time of year studied. Fescue-red clover was consistently inferior in all respects. The digestible dry matter intake by cattle grazing alfalfa-orchardgrass, bluegrass-white clover and fescue-red clover was 3.2, 2.9 and 2.2 kg/d, respectively. More work needs to be done on a wider variety of pastures during different times of the grazing season. / Master of Science

A series of four trials over the grazing season were conducted to evaluate the nutritional status of beef cows grazing reclaimed strip-mined pastures in southwestern, Virginia. Blood samples, esophageal fistula forage samples and hand plucked forage samples were taken in each trial. An external marker, Ytterbium, and an internal marker, indigestible neutral detergent fiber (INDF) were used to estimate organic matter intake, fecal output and digestibility. In addition to samples taken during the trials, blood samples and hand plucked forage samples were taken monthly for 11 mo prior to the trial period. In late summer esophageal masticate samples had a low fiber fraction (ADF and NDF), high crude protein and total nonstructural carbohydrates (TNC) which contributed to a high organic matter digestibility. Hand plucked forage samples had higher TNC than esophageal masticate samples. Organic matter digestibility predicted by the internal marker was highest in late summer 61.6%, similar in spring and late fall, and lowest in mid-summer, 52.6% (p < .01). Fecal output was highest in mid-summer and lowest in spring (p < .05). Estimated intake was not significantly different in any of the trials. Although data was variable, forage quality was higher in May, June, October and November samplings, as indicated by highest CP, TNC, and lower NDF and ADF values, compared with July and August data when forage quality was lowest. Packed cell volume, BUN and serum P and Mg concentrations fell within normal ranges for beef cattle. Low BUN values were observed in spring and late fall which corresponded to low crude protein values observed in the esophageal masticate samples for the same trials. Serum Cu was on the low end of normal values in the late spring and decreased to .6 ppm by late fall. Serum K levels were above the expected values for beef cattle. Serum Na concentrations were lower than normal with lowest values observed throughout spring and summer months. / M.S.

Master of Science

Fertilizer and lime investigations to determine their effect upon crops and soils have been carried out at many experiment stations. The correlation of the yield, the type and the chemical composition of vegetation and changes taking place in chemical properties of soil will contribute to a better understanding of soil fertility problems. Since 1940 the Virginia Agricultural Experiment Station, in cooperation with the Tennessee Valley Authority has conducted a pasture experiment on Coeburn Silt Loam in Wise County, Virginia. Several different fertilizer treatments with and without lime, were used to evaluate their effect upon pasture vegetation. The purpose of this study is to determine the extent of and nature of the effects of certain fertilizers and lime treatments on pasture vegetation and on the soil. The experiment was conducted on Coeburn Silt Loam, a soil derived from interbedded shale and arkosic sandstone. This soil is well drained, occurs on rolling to hilly relief, is low in inherent fertility and is fairly well adapted to agricultural uses. / Master of Science

Over the past several decades, native and managed bee populations have decreased in the United States and worldwide. Although bee decline is attributable to several factors, habitat loss is the primary driver. Simultaneously, cattle producers in the eastern U.S. rely primarily on cool-season forages that peak in biomass production in late spring, leading to a lack of forage in the summer months and increasing the costs of cattle production. Seeding pastures with a mix of native warm-season grasses and native wildflowers could increase forage availability while also increasing available resources for bees. In this study, a mix of three native warm-season grasses (NWSGs) and 15 wildflower species was planted at the Virginia Tech Shenandoah Valley Agricultural Research and Extension Center (SVAREC). The objectives of this project were to document the establishment and species composition of NWSG + wildflower pasture mixtures, compare the attractiveness of wildflowers and weedy species to bees, and compare the bee community between NWSG + wildflower pastures and more typical cool-season grass pastures. The wildflowers in the NWSG + wildflower pastures dominated over grasses. All wildflower species that established were attractive to bees, as were some weedy species. The NWSG + wildflower treatments had the highest abundance of bees collected, with an average of 14.8 bees collected per pasture per sampling date in 2018, and an average of 12.4 bees collected per pasture per sampling date in 2019. These results indicate that with modification of establishment methods so that more grasses are present, this pasture system could be beneficial from both a cattle production and bee conservation standpoint. / Master of Science in Life Sciences / Over the past several decades, there has been a decline in bee populations in the U.S. and around the world. Bees play an important role in pollinating many food crops, including most fruits and vegetables. Habitat loss is the biggest contributor to their decline. There are also issues with cattle production in the eastern U.S. Most farmers rely on grasses that are the most productive in the late spring and early summer, meaning that by mid- and late summer, there is little grass available for cattle. Planting pastures with native grasses designed to be the most productive in the late summer and native wildflowers could increase food available for cattle as well as provide more pollen and nectar for bees. In this experiment, we planted a mix of three grasses and 15 wildflowers. We documented how well the grasses and wildflowers established. We also examined how attractive wildflowers and weeds were to bees and compared the number and types of bees collected between the new pastures and traditional pastures. We found that the wildflowers, instead of the grasses, dominated the pastures. All wildflowers that established, as well as some weeds, attracted bees and provided resources. Higher numbers of bees were collected in the pastures with wildflowers than standard grass pastures, but there were not necessarily more bee species present. These results suggest that, with some modifications, planting native grasses and wildflowers in pastures could help conserve bees as well as benefit cattle farmers.

Estimates of feed produced by pasture were obtained from pasture investigations at the Tidewater Field Station from 1949 through 1953, Dry lot groups of pigs similar to those fed on pasture and fed similar rations were used to estimate total concentrates necessary for maintenance and gain of pigs on pasture. Feed production of each pasture was estimated from the difference between concentrates consumed by the pigs on that pasture and total concentrates for similar performance in dry lot. Estimates for 1949 and 1950 were based on the regression of feed consumption on average daily gain of pigs fed in dry lot. Weight of the animals was not considered in computing these estimates, In 1952 and 1953 the regression of feed consumption on weight was the basis for estimates when pigs were fed at the high level of nutrition, end feed required per pound of gain above maintenance for similar weight pigs was the basis for estimates, when pigs were fed at the low level of nutrition. Direct comparisons were made between pigs fed in dry lot and on pasture at the high level of nutrition, since feed consumption and weight were similar, This was not the case with pigs fed in dry lot and on pasture at the low level of nutrition. Feed consumption was the same but average daily gain differed significantly. Since the low level of nutrition provided slight gain for pigs in dry lot, it was necessary that this gain be subtracted from the total gain made by pigs on pasture. The net gain was assumed to be the direct result of the pasture, The feed required per pound of gain above maintenance was calculated and multiplied by the net gain (gain made from pasture), the product being an estimate of the feed replacement value of the pasture lot. Estimations were calculated on a per acre basis. A summary by years of the feed replaced by the pasture is shown in Table 15. This summary indicated that a more consistent estimate was obtained when weight of the animals was included in estimating expected feed consumption, Exceptions to this occurred in 1952 and 1953 when pigs were self-fed on ladino clover. In 1952, the estimated feed replacement value of the pasture, when pigs were provided supplement, was 584 pounds, while in 1953 the estimate was 93 pounds. When supplement was not included in the ration, the feed replaced by the pasture was 26 and 903 pounds for 1952 and 1953, respectively. / Master of Science

Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The aim of this study was to determine the effect of a grass herbicide, a broadleaf herbicide with some grass control capabilities, method of tillage (tine and no-tillage) at planting of wheat as well as different medic cultivars on the regeneration, dry matter (OM) production and quality of a medic pasture. The trial was conducted at Langgewens experimental farm in the Swartland wheat producing area. Nine medic cultivars of three different species were evaluated after being sprayed with either haloxyfop-R-methyl (HAL) ester or imazamox (IMI) and subjected to either a tine tillage or a no tillage treatment at planting of wheat. Soil samples were taken during January 2000 to determine the size of the medic and weed seedbank as well as the degree of dormancy in the medic seeds, while OM samples were taken throughout the growing season to determine the OM production of the different medic cultivars and weed species. OM samples taken during October 1998 on the same pasture, were used to determine the crude protein (CP) and neutral detergent fibre (NOF) content of the pasture. The samples were subjected to in vitro digestion and the digestibility of pasture CP (OCP), NOF(ONOF) and DM (DOM)were determined. Results showed that seedling establishment differed between cultivars used, herbicide treatments applied as well as the crop stage in the rotation. The cultivars produced more seedlings where IMI was applied compared to HAL as well as where the area consisted of two year pasture compared to one year pasture (1998) and one year wheat (1999). After a year of pasture and a year of wheat, cultivars Sephi and Paraggio produced the most seedlings, while Caliph and Orion produced the least. Caliph however, showed a very high degree of seed dormancy while Orion's low seedling establishment was due to its sensitivity to the IMI herbicide used. Little difference was found between the nine cultivars early in the season (July - August) with regard to cumulative OM production, except for Orion, whose growth was severely damaged by the IMI treatment. At the end of the growing season (October), the cultivar Caliph's cumulative OM production (2010.1 kg/ha) was significantly higher than all the other cultivars, except for Parabinga (1053. 4 kg/ha). Oifferent pasture samples, of which the botanical composition was known, was analysed for CP, NOF, OOM, OCP and ONOF. There was no significant difference in pasture composition during 1998 but variation in the pasture composition did however cause the IMI treatment, compared to the HAL treatment, to have a lower ONOFand OOMcontent. A modelling procedure was used to predict the pasture quality parameters (CP, NOF, OOM,OCP and ONOF) from the pasture composition (medic hay, medic pods, grassy and broadleaf weeds). This prediction of CP, NOF, OOM, ONOF and OCP from the pasture components had a relative low accuracy (49 -74.1 %) and a further refinement of this model for possible use on farms in order to improve grazing management and animal production is advised. In conclusion it could be said that broadleaf weed control caused a definite increase in medic seed and OMproduction, but Orion should not be used with an IMI herbicide. All the cultivars, except for Orion, produced enough seedlings up to the second year to ensure sustainability of the medic pasture. All the cultivars, except for Orion, produced a sufficient amount of OM early in the growing season. Caliph however, produced by far the most OM later in the growing season. A reduction of broadleaf weeds and medic pods will increase the digestibility of NOFand OMand therefore increase the quality of the pasture. Pods however are an important part of summer forage and the aim should therefore rather be to reduce the number of broadleaf weeds in the pasture. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van 'n gras en breëblaar onkruiddoder (wat sekere grasse beheer), metode van bewerking tydens die saai van koring asook nege verskillende medic kultivars op die regenerasie, droë materiaal produksie en kwaliteit van medic weidings te bepaal. Die proef is gedoen op Langgewens proefplaas wat geleë is in die Swartland koring produserende gebied. Nege medic kultivars is geëvalueer nadat die weiding met of haloxyfop-R-metiel ester (HAL) of imazamox (IMI) onkruiddoders gespuit is en onderwerp is aan of 'n vlak tand of geen bewerking tydens die saai van koring. Grondmonsters is geneem in Januarie 2000 om die grootte van die medic en onkruid saadbank asook om die graad van dormansie in die verskillende medic kultivars se sade te bepaal. Droë materiaal monsters is gedurende die 2000 groeiseisoen geneem om die droë materiaal produksie van die verskillende medic kultivars asook onkruid spesies te bepaal. Droë materiaal monsters is gedurende Oktober 1998 geneem en gebruik om die ruproteïn (CP) en neutraaloplosbare vesel (NDF) inhoud van die weiding te bepaal. Die monsters is in vitro verteer en die verteerbaarheid van CP (OCP), NDF (ONOF) en droë materiaal (DOM) is bepaal. Resultate wys dat saailing vestiging verskil tussen die verskillende kultivars wat gebruik is, verskillende onkruiddoder behandelings asook die stadium van die weidings/koring. Die kultivars het meer geproduseer waar die weiding met IMI behandel is in vergelyking met waar HAL toegedien is, asook waar koring nog nie gesaai is nie. Na 'n jaar van weiding en 'n jaar van koring, het die kultivars Sephi en Paraggio die meeste saailinge, en Caliph en Orion die minste saailinge gehad. Caliph het egter 'n hoë graad van dormansie in sy saad getoon, terwyl die swak vestiging van Orion die gevolg is van die kultivar se hoë sensitiwiteit teenoor IMI. Min verskil is gevind tussen die nege kultivars, vroeg in die groei seisoen (Julie - Augustus), wat kumulatiewe droë materiaal produksie betref, behalwe vir Orion wat erg beskadig is deur die IMI behandeling. Aan die einde van die groeiseisoen (Oktober 2000) was die kumulatiewe droë materiaal produksie van die kultivar Caliph (2010.1 kg/ha) betekenisvol hoër as al die ander kultivars behalwe vir Parabinga (1053.4 kg/ha). Weidingsmonsters, waarvan die botaniese samestelling bekend was, is ontleed vir CP, NDF, DDM, DCP en DNDF. Daar is geen betekenisvolle verskille gevind in die botaniese samestelling van die weidingmonsters geneem in 1998 nie,maar die variasie in botaniese samestelling het veroorsaak dat IMI in vergelyking met HAL 'n laer DNDF and DDM inhoud het. 'n Model is opgestel wat die weidingskomponente (medic hooi, medic peule, gras en breëblaar onkruide) gebruik om die kwaliteits parameters (CP, NDF, DDM, DCP en DNDF) van die weiding te skat. Hierdie skatting van CP, NDF, DDM, DCP en DNDF deur van die weidingskomponente gebruik te maak het 'n relatiewe lae akuraatheid gehad (49 -74.1 %) en verdere verfyning van hierdie model vir moontlike gebruik op plase, ten einde weidings bestuur en diere produksie te verbeter, word voorgestel. Die gevolgtrekking kan gemaak word dat breëblaar onkruidbeheer 'n definitiewe verbetering in die medic saailing en droë materiaal produksie van die medies te weeg gebring het, maar die kultivar Orion behoort nie saam met 'n IMI gebruik te word nie. AI die getoetste kultivars, behalwe Orion, het voldoende saad oorlewing vertoon tot en met die tweede jaar van die rotasie om lewensvatbaarheid van die sisteem te verseker en alle kultivars, behalwe Orion, het voldoende droë materiaal produseer vroeg in die groeiseisoen. Caliph het egter laat in die groeiseisoen by verre die meeste droë materiaal geproduseer. 'n Vermindering in die hoeveelheid breëblaar onkruide en peule in die weiding sal tot 'n verhoging in die verteerbaarheid van NDF en DM lei en dus 'n verhoging in die kwaliteit van die weiding tot gevolg hê. Peule is egter 'n belangrike bron van voedsel aan weidende diere gedurende droë somermaande en die verbetering van weidings moet eerder gedoen word deur te poog om breëblaar onkruide te beheer.

Over the past thirty years, price relativities and technological development have motivated an increase in the area of land allocated to cropping, as opposed to pasture production, throughout the central wheat belt of Western Australia. Nevertheless, reducing the proportion of pasture in these rotations has challenged the future productivity of farming systems in this area. First, the frequent application of selective herbicides for weed control in extended cropping rotations has promoted the development of herbicide resistance in a number of major agricultural weeds. Second, the primary use of annual plants has promoted the development of soil salinisation by allowing a significant proportion of rainfall to recharge saline water tables. The inclusion of perennial pasture phases between extended periods of cropping may mitigate or delay these constraints to production through (a) allowing the use of costeffective forms of non-selective weed control, and (b) through creating a buffer of dry soil that absorbs leakage occurring beneath subsequent crops. This study consequently explores the value of including perennial pasture phases in dryland agricultural systems in the eastern-central wheat belt of Western Australia, accounting for benefits related to herbicide resistance and water table management. A novel computational algorithm for the solution of multiple-phase optimal control problems is developed and used to conduct a conceptual analysis of the value of lucerne (Medicago sativa L.) pasture for managing annual ryegrass (Lolium rigidum Gaudin), the primary weed in wheat belt cropping systems. The competitiveness and fecundity of annual ryegrass provide strong economic incentives to maintain a low weed population, irrespective of herbicide-resistance status. Consequently, the ineffectiveness of selective herbicides primarily reduces the profitability of cropping by motivating the adoption of more costly non-selective forms of weed control. The inclusion of lucerne in land-use rotations is only optimal in the presence of severe herbicide resistance given (a) the low efficiency of alternative weed-management practices available during the pasture phase, relative to selective-herbicide application; (b) the significant cost of establishing this perennial pasture; and (c) the high relative profitability of cereal production in the absence of resistance. The value of lucerne, relative to annual pastures, for weed management is explored in greater detail through the use of compressed annealing to optimise a sophisticated simulation model. The profitability of candidate rotations is also manipulated to account for the long-term production losses accruing to the recharge of saline groundwaters that occurs beneath them. Sequences incorporating lucerne are only more profitable than those that include annual pasture at the standard set of parameter values if (a) annual ryegrass is resistant to all selective herbicides, (b) the water table is so shallow (approximately less than 3.5 m deep) that frequent rotation with perennials is required to avert soil salinisation, or (c) sheep production is highly profitable. The value of perennial pasture is sufficient under these circumstances to overcome its high establishment cost. Consistent with intuition, these benefits are reinforced by lower discount rates and higher rates of leakage occurring beneath annual-based systems. Formulation of an effective communication strategy to report these results to producers is justified given the complexity involved in determining the true magnitude of these intertemporal benefits through alternative means, such as field trials.

No abstract available. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1986.