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Typescript. / Thesis (Ph. D.)--University of Hawaii, 1968. / Bibliography: leaves [197]-208. / xiii, 208 l illus., tables

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

Digitized by Kansas Correctional Industries

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Isotope and dye estimates were made of body fluid compartment sizes in White Leghorn roosters, Glaucous-winged gulls, and in groups of Pekin ducks which were raised on either fresh water or regimes of hypertonic NaCl solution. The gulls and both groups of ducks were observed to have plasma (T-1824 dye) and total body water (H₂³O) volumes larger than thoseof the roosters, whereas the reverse was true for Br⁸² space (extracellular fluid; ECF) measurements. Salt fed ducks showed smaller, but insignificantly different compartment sizes (% body weights) when compared to fresh water raised ducks. The effects of an intravenous injection of hypertonic NaCl on the distribution of body water were compared among birds which differed in their capacity for renal and extra-renal salt elimination. In those birds (gulls, salt water ducks, and fresh water ducks with functional salt glands) which exhibited extra-renal salt secretion, the increase in ECF was significantly greater in response to the intravenous injection of hypertonic NaCl than in those birds (roosters and non-secreting fresh water ducks) which did not utilize the salt glands. The relative amounts and concentrations of the salt load removed by renal and extra-renal routes of elimination were compared. Birds with actively secreting nasal glands voided a major equivalent of the injected NaCl as solutions hypertonic to plasma NaCl levels. Renally eliminated NaCl represented a much smaller portion of the load and was in all cases hypo- or isotonic with plasma ion levels. Isotopically labelled Na²² CI administered concomitantly with the salt load in several of the test birds revealed that a large portion of the labelled sodium chloride was removed by the nasal glands and kidneys before there was equilibration of the injected load with extravascular compartments. A preliminary report is made on the composition and possible source of an excess eye secretion observed in the rearing of saline fed Pekin ducks. The enlarged Harderian glands of these birds were implicated as the source of a fluid several fold hyperkalemic to plasma ion concentrations. The secreted fluid was observed to accumulate and encrust the feathers below the inner canthus of the eye. / Science, Faculty of / Zoology, Department of / Graduate

Four studies were conducted to assess the use of electrical shock on several parameters of avian muscle that contribute to its ultimate quality. In the preliminary study, the effect of preslaughter electric stunning on the tenderness of broilers processed and handled in a standard commercial manner was assessed. The tenderness of cooked breast muscle samples was evaluated by Kramer single blade shear force values. This evaluation indicated that samples from the electrically stunned birds were significantly more tender than those from the no stun controls (p<0.01). The effects of varying the duration, frequency and voltage of a post-exsanguination stimulatory current on the development of rigor mortis and the postmortem glycolytic rate were investigated in Study One. The pH of muscle homogenates at various postmortem sampling times was used as an index of glycolysis whereas rigor development was monitored by the isometric tension technique. Postmortem glycolysis in Biceps femoris and Pectoral is major samples was accelerated by electrical stimulation, as was the time course of rigor development. Pectoral is major samples from treated carcasses required significantly less time to develop maximum tension than control samples (p<0.05). Although Biceps femoris samples from stimulated carcasses also exhibited decreases in the time required to achieve maximum tension when compared to controls, these differences were not significant. Pectoral is maj or samples from carcasses treated with 70V for 2 minutes at either 40 or 80 pulses/s developed significantly lower tension than control samples (p<0.05). No significant differences due to the voltage or total number of pulses were observed for either the time required to achieve maximum tension or the maximum tension developed. The influence of electrical stimulation on the development of rigor was further examined in Study Two. Rigor development again was monitored by the isometric tension technique and changes in metabolite contents for both muscle types were determined by enzymatic analytical techniques. Electrical stimulation reduced the time required by Biceps femoris and Pectoral is major samples to reach maximum tension but this decrease was only significant for the latter (p<0.05). The amount of isometric tension developed by both muscle types was similarly reduced by electrical stimulation. The initial glycogen and ATP contents of both muscles were reduced by electrical stimulation, as were their ATP contents at subsequent sampling periods. Several correlations between the parameters of isometric tension and metabolite contents were noted and regression equations were developed to express the significant relationships. No significant differences due to electrical stimulation in the rate of isometric tension release were observed, but Pectoralis major samples from stimulated carcasses released their developed tension more rapidly than their respective Biceps femoris samples. In the final study, Study Three, the effect of electrical stimulation on muscle proteolytic activity was assessed by two analytical methods for TCA soluble material. In addition, changes in protein extractability, dispersibility and hydrophobicity were followed in control and treated samples during storage for one day at 2°C. Electrical stimulation significantly reduced the time required to reach maximum tension (p<0.05) and decreased the maximum tension achieved for Pectoralis major and Biceps femoris muscle samples. Pectoralis major samples from treated carcasses again released their developed tension faster than their respective Biceps femoris samples. When the muscle samples were analysed for nonprotein nitrogen, neither measure indicated a significant treatment effect. In a similar manner, neither extractable protein, protein dispersibility nor protein hydrophobicity were affected by electrical stimulation. / Land and Food Systems, Faculty of / Graduate

The role that climate plays in the ecology of organisms is perhaps the most pronounced where the earth’s environments are most extreme. In arid-zones, organisms have to deal with large seasonal shifts and/or extremes in temperature and/or moisture levels. As a result, arid-zone species are sensitive to climatic changes. I assessed the physiological and behavioural adjustments of an arid-zone endemic passerine, the rufous-eared warbler (Malcorus pectoralis), to seasonal changes in the Karoo semi-desert of South Africa. Respirometry measurements in the field showed that the warblers’ basal metabolic rate was lower and set point body temperature (Tb) was higher in summer compared to winter. At high air temperatures (Ta) evaporative water loss (EWL) rate was significantly lower in summer compared to winter, while Tb showed a clear pattern of heterothermy that was similar in both seasons. Compared to winter, the warblers in summer were able to remain calm, and tolerate higher Ta’s, before their Tb’s increased to potentially detrimental levels. Behavioural observations showed that free-living warblers exhibited significant temperature-dependence in their behaviour; they increased panting behaviour, and reduced activity levels, time spent preening, and foraging effort at high Ta’s in summer. The warblers also displayed a considerable decrease in foraging success, and a shift in microsite use, at high Ta’s in summer. I hypothesise that the flexible responses the rufous-eared warblers show are aimed at increasing their heat tolerance in summer, and help them balance their energy and water demands in an arid environment that exhibits wide seasonality in Ta, in addition to high summer Ta. My findings emphasise the importance of identifying, as well as understanding, the associated costs of physiological and behavioural responses to environmental variables. This information is valuable in terms of predicting biologically meaningful responses (and hence, vulnerability) of arid-zone avian communities to climactic shifts.