This study describes annual hormone cycles in wild and captive harbour seals, considers hormonal changes in wild grey seals during their lactation period, investigates the changing responsiveness of the pituitary-gonad axis throughout the year to stimulation with small single doses of gonadotrophin releasing hormone (GnRH) and addresses the possible influence of the experimental techniques upon the results using plasma cortisol concentrations as an index of stress. In captive harbour seals, LH concentrations through the year were significantly different only in the pregnant female. Plasma FSH concentrations were significantly different throughout the year only in the two non-pregnant females, being highest during delayed implantation. Plasma progesterone concentrations were significantly different throughout the year in both the pregnant and non-pregnant females. In wild harbour seals, plasma FSH concentrations were not significantly different throughout the year in the adult females but were significantly different in the immature females between stage 1 and 4 (post-partum oestrus and late gestation for the mature females). Plasma progesterone concentrations were significantly different throughout the year only in the adult females. In wild male harbour seals plasma testosterone concentrations were significantly different in adults between the pre-breeding and breeding season, being highest in the pre-breeding season. In wild lactating grey seals, plasma progesterone and FSH concentrations were low throughout most of lactation but increased late on. Plasma prolactin concentrations were highest during mid-lactation decreasing at the time when behavioural oestrus was observed. In all captive harbour seals and wild and captive grey seals an increase in plasma LH concentration was measured following GnRH administration returning to pre-GnRH concentrations within ninety minutes. In lactating female grey seals the magnitude of the LH response was smaller than in the other animals but was more prolonged.

Two aspects of the biology of red deer: were studie,|, namely, energy metabolism and seasonal cycles. The energy metabolism of young red deer was investigated in three experiments. Firstly, a comparison wss made of the utilisation of a diet by deer and sheep during their first year, by estimates of nitrogen and energy balance. No significant differences in digestibility, metabolizability, or efficiency of utilisation of feed nitrogen and energy were recorded between the species, but there were differences in carcass composition, heat production and maintenance requirement. ; Secondly, measurements were made of the physiological responses of young deer to the stresses of cold arid undernutrition, Hesults suggested that the deer may be less adapted to cold than sheep or cattle, especially when underfed. Finally, gaseous exchange was measured out-of-doors during winter by means of a face mask and the results compared with the previous experiment where cold stress had been imposed in a respiration chamber. A concurrent study was made of the photoperiodic control of seasonal cycles in male red deer. In the first experiment four stags were subjected to a 6-month photoperiod for two years and measurements were made of their growth, appetite and sexual condition. The experiment was then repeated, with certain modifications, and involved sheep as well as deer. Body weight, voluntary food intake, antler growth, testicle size and plasma testosterone concentration showed cyclic fluctuations related to the imposed daylength cycle. The importance of daylength as a stimulus to seasonal activity was confirmed. A subsidiary investigation was made of the effect of tranquillising drugs on the appetite of red deer.

No description available.

This thesis presents the results of a series of experiments carried out to determine if bacterial single-cell protein (BSCP) could replace fishmeal in a pelleted diet in rainbow trout (Oncorhynchus mykiss (Walbaum)) and to investigate the quantitative lysine requirement of this species using a methodology for the measurement of individual food consumption rates viz. radiography. In the first investigation, four diets were formulated to contain a total of 45.8% crude protein of which 0% was from BSCP in BSCP-0, 25% in BSCP-25, 62.5% BSCP-62.5 and 100% in BSCP-100; the remainder of the protein being from fishmeal. Food consumption rates of individual fish were measured using radiography. The results show that 100% BSCP diet resulted in significantly higher food consumption rates but was associated with a reduction in N absorption efficiency, growth rates and N growth efficiencies when compared to the diet that contained no BSCP. The diet containing 25% BSCP did not significantly influence growth rates, food consumption or absorption efficiency when compared with a 100% fishmeal diet. Construction of N budgets demonstrated that the reduction in growth of fish eating an increasingly larger proportion of BSCP was due to a decrease in N absorption and an increase in the excretion of urea. The nutrient absorption efficiency shows that even though the four dietary groups were well balanced in terms of known amino acid requirements in trout, fish fed on the BSCP-100 diet absorbed below requirement level in respect of some amino acids due to the poor absorption efficiency of this diet.

No description available.

No description available.

No description available.

No description available.

A model was developed in the rat using a nerve crush procedure, as a form of temporary denervation, to block neural input to the hindlimb muscle of one leg. The nerve crush has the advantage of allowing self-reinnervation of the muscles after regrowth of the damaged nerve, which occurred (in this study) after approximately 14 days. The initial denervation-like phase resulted in a large loss of muscle mass over the subsequent few days which was mostly through a loss of muscle protein. The results demonstrate the correlation between the concentration of glutamine in the muscles and the rate of protein synthesis over the first 3 days after the nerve crush, but other metabolites (alanine, lactate, and glutamate) were seen to react much more rapidly, with significant changes recorded in the first hour after injury. Further studies were undertaken in an attempt to find a link between these acute changes and the later changes in protein and glutamine metabolism. It was demonstrated that these rapid changes were not as a result of a local hypoglycemia, although a reduction in the rate of in vivo glucose uptake was reduced within 4 hours of the nerve crush. Similarly, measurement of activities of key glycolytic enzymes suggested that there were no acute changes in flux through the glycolytic pathway. Finally, a difference in regional blood flow was demonstrated in the experimental muscles and it was concluded that the acute changes in metabolite concentrations might result from simple physiological changes, in response to the anaesthesia and/or the surgical procedure, which subsequently resolved in the innervated, but not the nerve-deprived, muscles.

The locomotory response of the decapod, crangon crangon, to high hydrostatic pressure has been investigated by an observational method. It was found that the shrimp exhibits sensitivity to high pressure by becoming hyperactive and undergoing 'convulsions' And 'tail-twitches'. The onset of such a convulsive phase was, + 5-2 On average, (51.7 - 3.1) x 10 n.m. (N = 22) when compressed At a rate of 103.4 x 10[superscript5] n.m. -2 Hr.-1, But this was lowered to + 5-2 (34.5 - 5.1) X 10 n.m. (N = 5) when compressed at only 5~2~1 20.7 X 10 n.m. Hr. Shrimps with the ventral nerve cord Cut in the rostral portion of the abdomen, exhibited convulsions at approximately 2.5 times that in intact animals. Homarus gammarvs, a common lobster, exhibited similar Behaviour to the shrimp when exposed to high pressure. A compression rate of 103.4 x 10 n'.m.~ hr-1. resulted in an onset Of vigorous tail-flip activity at a mean pressure level of (92.3. - 10.7) X 10n.m. (N = 9). When compressed at 5-2-I 20.7 X 10 n.m. Hr.,The mean pressure at which this hyper-I c - 2 activity began, was lowered to (53.8 - 18.6) x 10 [Special character omitted] n.m., Although the activity was not vigorous and often only involved flaring of the uropods and slow flexing of the tail. When the crustaceans were maintained at a specific Pressure level over several hours, adaptation to pressure was Only observed at the moderate pressures (51.7 x 62.0) x 10 -2.N.m.. This was indicated by a decline in convulsive activity. At higher pressures convulsive activity declined, but repression of all muscular activity was evident. At lower pressures, long exposure led to the onset of. Convulsive activity. This was illustrated by c. crangon. Transecting the abdominal ventral nerve cord caudal to the point of recording (inn. gammarus), tail-flip activity was induced by pressure within the normal range. The mean convulsion threshold pressure level was (89.5 - 8.6) x 10 N.m.(n =6). However, transecting the nerve cord rostral to the point of recording led to an inability of the animals to flex their abdomens. Hyperactivity was evident by twitching in the anterior appendages, by rapid pleopod movement and by fanning of the uropods. In a group of six animals, this started to occur at approximately 93.1 x 10 N.m. By implantation of silver/silver chloride bipolar electrodes, "in vivo, on the abdominal ventral nerve cord, spontaneous nerve action potentials were recorded from the intact nerve, during compression of the animal, at the period when the animal was undergoing convulsive activity. Such spontaneous activity was net recorded when the electrodes were placed caudal to a transection of the transected nerve cord. Pressure also changed the shape of the evoked' compound action potential, however not all the changes were statistically significant. The general trend was that on compression to 2.06,8 x 105 N.m.-2 the threshold stimulus strength increased, the amplitude of the compound action potential decreased [Special character omitted] and the duration and delay of the peak of the compound action potential from the. stimulus artefact also increased. The isolated sciatic nerve of frog was used to compare the effects of hydrostatic pressure on the compound action potential, evoked in the purely axonal nerve bundle, with that evoked in the more complex synaptically interrupted nerve cord of h. gammarus. High hydrostatic pressure affected the evoked compound of the axonal nerve bundle in the same way it affected that of the lobster ventral nerve cord. In addition it was found that low temperature conditions (particularly below 14°C) augmented the effects of high pressure on the action potential. The results of these electrophysiological studies were compared with the observations made of the High Pressure Nervous Syndrome in decapods. Both excitatory and depressant effects were discussed, with reference to the relevant literature. Future experiments leading from this investigation were also discussed.