Isolation of the Toxic Principle of \u3cem\u3e Senecio latifolius \u3c/em\u3eby Means of the Sensory Receptors of Sheep

The aversive substance of Senecio latifolius was isolated by means of the sensory receptors of sheep averted to S. latifolius. Chemical fractions refused due to the presence of the aversive substance sensed by the sheep were fractionated until a purified substance had been isolated. Nuclear magnetic resonance (NMR) analysis of the purified substance showed it to be sceleratine nitrogen oxide, the toxic principle of S. latifolius

Sceleratin Nitrogen Oxide as Aversive Agent in Conditioning Livestock to Avoid \u3cem\u3eSenecio latifolius\u3c/em\u3e

Sceleratine nitrogen oxide, when administered together with a dichloromethane extract of Senecio latifolius, successfully conditioned cattle and sheep to avoid milled freeze dried S. latifolius mixed with maize meal. This treatment was effectively applied in conditioning steers to refuse eating S. latifolius grown in pots

Aversion Properties of Retrorsine, Retrorsine Nitrogen Oxide and Frosted Senecio latifolius

Two pilot trials, investigating the aversive properties of retrorsine and retrorsine nitrogen oxide and that of frosted Senecio latifolius, were executed. Retrorsine and retrorsine-NO (the toxic principles of Senecio retrorsus), unlke sceleratine-NO (the toxic principle of another hepatotoxic pyrrolizidine alkaloid containing plant, namely S. latifolius), were not capable of establishing aversion when given to a sheep. Frosted S. latifolius given to a sheep also did not induce aversion. However, a sheep averted to S. latifolius (non-frosted) refused eating frosted S. latifolius

Qualitative characteristics of selected Atriplex nummularia (Hatfield Select)

This study was conducted in two trials. The aim was firstly to identify the qualitative characteristics of Atriplex nummularia (Hatfield Select). Goats and sheep were used to identify three palatability groups of plants in the A. nummularia (Hatfield Select) paddock. These palatability groups were compared in terms of quality to one another. Secondly, qualitative and quantitative intakes of A. nummularia (Hatfield Select) by goats and sheep were determined. This was done in a grazing trial lasting five days. A comparison was conducted between goats and sheep as well as between the different days of the grazing period. During the first trial, goats and sheep were used to identify the most-, medium- and least-palatable A. nummularia (Hatfield Select) plants. The regrowth on these plants were harvested and used for laboratory analysis to identify the qualitative differences between these three groups. These samples were also used to determine and compare degradability between the three groups as well as between goats and sheep. Goats and sheep preferred A. nummularia (Hatfield Select) plants with a significantly (p ¡Ü 0.05) higher crude protein (CP), phosphorus (P) and magnesium (Mg) content. The most preferred plants also had higher neutral detergent fibre (NDF), Ca, K, Na, Cl- and Cu content than the least preferred plants, but these were not significant (p > 0.05). A. nummularia (Hatfield Select) provides enough CP for maintenance and production in both goats and sheep. All mineral requirements for maintenance in goats and sheep can be satisfied on A. nummularia (Hatfield Select), except that of Cu. For production (growth and lactation) only P is deficient and needs to be supplemented. A. nummularia (Hatfield Select) makes an ideal drought fodder crop to support the natural veld during the dry season. An overall higher DM, N and NDF rumen degradability of Atriplex was recorded with goats than with sheep. Goats exhibited a significantly (p ¡Ü 0.05) higher DM and N degradation and although a higher NDF degradation was also recorded, this was not significant. The rate of DM, N and NDF rumen degradation was also higher in goats than in sheep. This means that goats have a more favorable rumen environment for the digestion of A. nummularia (Hatfield Select). DM and N degradation were also significantly (p ¡Ü 0.05) higher in the most palatable group than the least palatable group. NDF degradability decreased with palatability. This means that the most palatable plants have a higher digestibility and quality than the least palatable plants. In the second experiment, rumen and oesophageal fistulated sheep and goats were allowed to graze A. nummularia (Hatfield Select) for five days. Qualitative and quantitative intakes were determined. The quality and quantity of ingested material were compared between goats and sheep as well as between the different grazing days. There was a significant decline in the quality and quantity of intake over the grazing period. Some parameters were significant, for example CP. The CP concentration declined from 18% to 3.91 % for goats and from 19.88% to 6.61% for sheep. The cell wall constituents (NDF) increased by about 10% from the start to the end of the grazing period. IVDOM decreased by 14% and intakes were almost halved from the start to the end of the grazing period. Other authors have also observed this decrease in quality and quantity of intake over time. The lower quality and quantity in intake was because of a decline in the availability of high quality edible material. At the end of the grazing period, there was very little edible material left which caused an extremely low quality and quantity of intake. Rumen NH3-N concentrations also declined as the dietary CP declined, but it was still present in high enough concentrations to sustain the rumen micro flora population. Rumen VFA decreased over the grazing period. The acetic acid to propionic acid ratio increased towards the end of the grazing period. This caused a decline in the efficiency of utilization of ME for maintenance as acetic acid has an efficiency in utilization of ME of 59% and propionic acid of 86% (McDonald et al., 1995). This means that energy will have to be supplemented to sustain maintenance.Dissertation (MSc (Agric) Animal Science, Nutrition)--University of Pretoria, 2007.Animal and Wildlife Sciencesunrestricte

Isolation of the Toxic Principle of \u3cem\u3eMoraea pallida\u3c/em\u3e by Means of the Sensory Receptors of Sheep

Chemical fractions of Moraea pallida were offered to a sheep in which aversion to the plant had previously been established. Fractions refused due to the presence of the aversive substance sensed by the sheep were further purified until a single substance had been isolated. The purified substance was characterized as epoxyscillirosidin, the toxic principle of M. pallida

Continuous exposure to an aversive mixture as a means of maintaining aversion to vermeerbos (Geigeria ornativa O. Hoffm.) in the presence of non-averted sheep

Continuous exposure to an aversive mixture was investigated as a means of maintaining aversion to vermeerbos in sheep subjected to the social influence of non-averted sheep. The use of an aversive mixture was based on a hypothesis that continuous exposure to an acceptable aversive mixture (containing both the aversive substance and the identification factors of vermeerbos mixed with maize meal) would tempt sheep to consume small quantities of the aversive mixture each day and that this would keep them averted to vermeerbos, despite the social influence of non-averted sheep. Persistent aversion to a vermeerbos-maize meal mixture (1:99 by mass) by sheep continuously exposed to such an aversive mixture, after an initial aversion conditioning with lithium chloride (LiCl, 160 mg/kg BM), was demonstrated. Aversion in adjacent controls not exposed to the aversive mixture only lasted for some time. A similar result was obtained when sheep were challenged for intake of a pure stand of established vermeerbos. Three sheep continuously exposed to an aversive mixture after an initial aversion conditioning totally refused grazing the vermeerbos during a 42-day trial, despite the social influence of three non-averted control sheep grazing vermeerbos on an adjacent site. These results were confirmed by a second replication the following year. Joint grazing for an hour a day by averted and non-averted sheep during the last seven days of this replication also resulted in total avoidance of vermeerbos by the averted animals, despite continued intake of vermeerbos by the control sheep.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Studies towards optimising the isolation of diplonine, a neurotoxin isolated from cultures of <i>Stenocarpella maydis</i> (Berk.) Sacc.

Diplonine, a mycotoxin that induces neurotoxic clinical signs in the guinea pig, resembling those occurring in cattle and sheep with diplodiosis, was isolated previously from a Stenocarpella maydisculture. Knowledge of the chemical properties of the toxin, which was characterised as a substituted ß-cyclopropylamino acid, enabled amendments in the present study to the initial steps of the isolation procedure. Extraction with water and fractionation by cation exchange chromatography improved the efficiency of isolation, potentially allowing the preparation of larger amounts of the toxin

Changes in sheep oesophageal diameter and function during Geigeria ornativa (vermeerbos) poisoning and subsequent recovery

Changes in the oesophageal diameter and function together with changes in body weight, feed intake and the cardiac pulmonary flow index were investigated during experimentally induced poisoning with Geigeria ornativa and subsequent recovery. This was performed under varying conditions for individual sheep. Results showed an increase in the esophageal diameter index (ODI) during vermeersiekte, accompanied with a decrease in oesophageal function (OF). Cessation of G. ornativa intake resulted in a considerable although incomplete recovery of the ODI. Recovery of the OF for the different sheep, however, varied between 0 and 100 %. Detrimental changes in the oesophageal diameter and function were also measured in sheep receiving only subclinical doses of G. ornativa. Decreases in body weight and feed intake commenced 1 to 3 weeks before the onset of vermeersiekte, while indications of a decline in these 2 parameters were also noticed with ingestion of subclinical amounts of G. ornativa. An increase in the cardiac pulmonary flow index (CPFI) to a value indicating the onset of heart failure was found in 1 of the sheep showing clinical signs of vermeersiekte. The CPFI returned to normal after termination of G. ornativa intake

Conditioned feed aversion as a means to prevent tulp (Homeria pallida) poisoning in cattle

Conditioned feed aversion was investigated as a means to prevent tulp (Homeria pallida) poisoning in cattle on tulp-infested grazing. Aversion treatment with a combination of epoxyscillirosidin and lithium chloride together with a tulp-hexane extract, which served as identification factor for tulp, resulted in a significantly lower (P < 0.001) proportion of severe tulp poisoning. In a first trial where 21 averted and 21 non-averted control cattle were exposed to a tulp-infested grass pasture, only two of the averted cattle were severely poisoned compared to 13 of the non-averted control cattle. In a second trial, with cattle being exposed to a pure stand of tulp supplemented with maize residues, only two of 21 averted cattle were severely poisoned compared to 14 of 21 non-averted control cattle. Occurrence of mild tulp poisoning, however, did not differ much between averted and non-averted control cattle. The results show that conditioned feed aversion effectively restricted severe poisoning in cattle on tulp-infested grazing.The articles have been scanned with a HP Scanjet 8300; 600dpi, saved in TIFF format. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format