Browsing by Author "Littin, Kate Elizabeth"

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    The behaviour, pathophysiology and pathology of brushtail possums (Trichosurus vulpecula) poisoned with 1080 or brodifacoum, and the implications for possum welfare : a dissertation presented in partial fulfilment of the requirements for the degree of Ph.D in Physiology at Massey University, Palmerston North, New Zealand
    (Massey University, 2004) Littin, Kate Elizabeth
    Millions of brushtail possums (Trichosurus vulpecula) are poisoned yearly in New Zealand owing to damage caused to agriculture and the environment. They are nonetheless sentient animals capable of suffering, and legislative and ethical obligations, and public concern demand that only the most humane poisons are used (Chapter 1). Accordingly, the aim of this work was to evaluate the effects of two poisons used for killing possums in New Zealand, 1080 and brodifacoum, and the implications for animal welfare. Animal Ethics Committee approval was obtained for all work. A lethal dose of 1080 in carrot baits caused retching, vomiting and seizures in possums caged indoors (Chapter 2). Possums did not fully lose consciousness until death but were likely to have been in a reduced state of awareness beforehand. The first signs of poisoning were observed after an average of nearly 2 h and they died on average 11.5 h after consuming baits, giving a period of potentially reduced welfare of approximately 9.5 h. Six possums of eight that consumed a sublethal dose showed signs of sickness, indicating that some sublethal doses can reduce welfare. Alphachloralose (a sedative) and paracetamol (an analgesic) had no effect on the behaviour of caged, 1080-poisoned possums (Chapter 3). The consumption of 0.88 mg/kg brodifacoum in cereal pellet baits by caged possums caused widespread haemorrhages which may have led to weakness, sickness or pain (Chapter 4). Possums did not lose consciousness until death after an average of 21 days but were likely to have been in a reduced state of awareness for up to six days beforehand. Signs of poisoning were first seen after 14 days on average, meaning welfare was potentially reduced for about seven days. Following the consumption of 0.86 mg/kg brodifacoum in cereal pellet baits, blood clotting ability was reduced and all possums had internal haemorrhages, both within eight days of bait being offered (Chapter 4). Possums penned outdoors with space for a high level of activity and exposure to spring and summer weather died after a lethal dose of 1080 or brodifacoum at about the same times as possums caged indoors, and following similar preceding signs of poisoning (Chapter 5). This implied that the second-most humane poison for possums and that broadifacoum is among the least humane (Chapter 6).
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    Plasma and faecal corticosterone in chickens (Gallus domesticus) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University
    (Massey University, 1998) Littin, Kate Elizabeth
    The overall aim of this thesis was to investigate stress, and plasma and faecal corticosterone secretion in chickens. It is known that social rank may be correlated with glucocorticoid levels and glucocorticoid responses to a stressor in both birds and mammals. The relationship between social rank and glucocorticoid secretion may only be evident during periods of increased environmental stress, such as that caused by social disruption. In the first experiment of the present study, the relationship between social rank index and corticosterone responses to a handling stressor was investigated before and after mixing together two unfamiliar groups of hens. Handling elicited corticosterone responses in most hens and the levels of corticosterone during a response and the magnitude of the response varied between individuals. Middle ranking hens tended to have elevated corticosterone responses to handling relative to low or high ranking birds, but overall, the results did not demonstrate a significant relationship between social rank and corticosterone levels during a corticosterone response or between social rank and the magnitude of the response. Mixing two groups of hens did not produce a sustained period of social stress so there was no concurrent increase in the number of aggressive interactions, corticosterone levels or corticosterone responses to handling after mixing. It was thought that this was because corticosterone responses and behavioural interactions were measured over days rather than hours, and the sampling protocol may have missed any changes in these variables that occurred within a few hours of mixing. The second experiment investigated the non-invasive measurement of corticosterone in cockerel droppings and the relationship between plasma and faecal corticosterone responses to an ACTH injection. An intramuscular dose of ACTH produced a peak in faecal corticosterone levels whereas two smaller intravenous doses of ACTH, which increased plasma corticosterone levels, did not significantly alter faecal corticosterone. This showed that faecal corticosterone levels may give a non-invasive measure of plasma corticosterone in chickens although the increase in plasma corticosterone levels might need to be large and sustained to be detected in the droppings. The magnitudes of the plasma and faecal corticosterone responses to ACTH were not correlated. Problems with the method used to extract corticosterone from droppings in this study may have affected faecal corticosterone measurements and the radioimmunoassay was not validated. As a result, a different extraction method is now used in our laboratory.