The developmental potential of mammalian oocytes cryopreserved with procedures similar to those used for embryos has been limited, inasmuch as oocytes differ from embryos in advanced stages of development, both physiologically and morphologically. The objective of this work was to elucidate the precise nature of freeze-thaw damage with the expectation that identification of specific targets will enable devising optimal procedures for cryopreservation of bovine oocytes to prevent specific damage and minimize the loss of developmental capacity. / In the first series of experiments, bovine oocytes were vitrified (V-oocytes) or frozen slowly (S-oocytes) at the germinal vesicle (GV) stage or after maturation in vitro (IVM). Survival was assessed morphologically and also by in vitro fertilization (IVF) and culture (IVC). Morphological integrity and developmental capacity were greater in S-oocytes than in V-oocytes (P $<$ 0.05). Transfer of four embryos (2 morulae and 2 blastocysts) derived from post-IVM S-oocytes into a recipient heifer resulted in the birth of twin calves. / In the second series of experiments, oocytes (GV and IVM) were exposed to a cryoprotectant solution (DAP213: 2M DMSO, 1M acetamide, 3M propanediol) for 1.5 or 5 min and viability assessed by IVM-IVF-IVC. Oocytes were also examined by transmission electron microscopy (TEM) before (control) or after exposure to the cryoprotectant. DAP213 induced profound premature cortical granule (CG) release and vesiculation. These changes were less pronounced in oocytes exposed to DAP213 only after IVM. The results suggest that: (1) the extrusion of CG is one of the important cytological events affected by the treatment of oocytes with DAP213; (2) GV oocytes are more sensitive to the cryoprotectant than IVM oocytes. / In the third series of experiments, GV and IVM oocytes were vitrified with DAP213. On rewarming, DAP213 was removed by a one- or three-step dilution procedure and survival assessed by development after IVM-IVF-IVC. Morphology was assessed by TEM study immediately following DAP213 removal. Both assessments indicated that: (1) IVM oocytes are more tolerant to vitrification than are GV oocytes; (2) the three-step dilution is less damaging than the one-step procedure; (3) changes in the zona pellucida (loss of plasticity) of IVM oocytes following vitrification may result from the premature release of cortical granules.

No description available.

The physical and physiological condition of larval fishes throughout their development is believed to influence their survival, and ultimately to contribute to recruitment to the adult population. The study of larval condition is therefore central to larval fish ecology. / In this thesis I sought to (1) carry out an appraisal of the characteristics and the reliability of condition measures now being used, (2) assess the importance of maternal contribution to the nutritional status of larval fish, (3) evaluate the possibility that diel variability in metabolism could lead to serious biasing of the interpretation of condition measures obtained over time, and (4) assess the time course of the condition of larval fishes subjected to periods of intermittent feeding. / The experiments described in chapter 2 were designed (1) to assess the impact of female nutritional status on the quality of the eggs and larvae they produced, (2) to determine which of a series of nucleic acid and protein measurements were most responsive to post-hatching starvation, and (3) to determine whether the starvation dynamics of those measures was affected by female source. No significant correlation could be found between any of the maternal traits studied and eggs and larval measures. The results did show, however, that egg size was more variable between-clutches than within-clutch, was independent of embryonic developmental rate, but was positively related to larval size. / The existence and ontogeny of circadian (24 hrs.) and ultradian (<24 hrs.) oscillations in the nucleic acids and protein content of larval capelin was investigated in the laboratory experiments outlined in chapter 3. The most obvious long-terms trends occurred during the embryonic period when DNA and RNA content increased constantly, and during the post-yolk-sac period when RNA and protein decreased following sub-optimal feeding. / The objectives of the study described in chapter 4 were threefold, (1) to determine which of a series of nucleic acid and protein measurements were affected by intermittent (delayed-fed and delayed-starved) feeding conditions in capelin larvae, (2) to determine the dynamics and shape of the time response, and (3) to determine whether the empirical data gathered were consistent with models developed as a consequence of the review of the literature (chapter 1). Only the dry weight, and the quantity of DNA, RNA, and protein per dry weight differed significantly between starvation and ad libitum feeding controls. Starvation dynamics were less consistent with predictions. Of the indices investigated, the dynamics of the quantity of DNA and RNA per dry weight were the most consistent dynamics with model predictions. (Abstract shortened by UMI.)

The first part of this study investigated the effects of varying temperature regimes within the range of 8-22°C on the development and survival of Atlantic salmon (Salmo salar L.) eggs and alevins. The temperature tolerance of eggs was lower than that of alevins: egg mortality increased above 11°C and no eggs survived to eyeing or to hatching at 16 and 14°C, respectively; alevin mortality increased above 16°C and no alevins survived at 22°C. Optimal survivals of eggs and alevins occurred at 8-11°C and 10-14°C, respectively. Subsequent survival at later stages of development was largely determined by survival at earlier stages. Developmental abnormalities among eggs (pin-eyed eggs) and alevins (abnormal hatching and yolk-sac oedema) appeared to be temperature-dependent. Development time in days from fertilisation to eyeing, hatching and maximum alevin wet weight (MAWW) varied inversely with temperature. The sum of degree-days from fertilisation to eyeing and to MAWW was similar at all temperatures, but declined with increasing temperature from eyeing to hatching. The hatching period was similar for all temperatures except 8°C where it was significantly longer. Although alevin size at hatching was not temperature-dependent within the range of 8-12°C, alevin size at MAWW decreased progressively with increasing temperature (10-20°C) during the alevin stage. Fry size at first feeding did not affect their subsequent growth rate or survival. Advanced fry which were fed earliest grew at similar rates to those produced at lower temperatures and attained the greatest weight. Biomass gain was more dependent upon survival than upon mean fish weight. The second part of this study investigated the effects of timing of first feeding on fry growth and survival. Alevins fed prior to final yolk resorption were larger and had lower mortalities than those fed after MAWW. Although the "window" of first feeding opportunity lasted several weeks, delaying feeding beyond MAWW reduced absolute growth. A 5-week delay led to mortalities approaching 60%. However, first feeding can be delayed beyond MAWW for 1-2 weeks at 10°C without adversely affecting subsequent survival or growth rate.

Energetic constraint during reproduction may limit the number or quality of young that a parent can produce per breeding attempt or the parent's longevity or future productivity, ultimately constraining lifetime reproductive success. The Eurasian dotterel Charadrius morinellus experienced energetic constraint during the Incubation period. Dotterel breed in the cold arctic-alpine zone and most breeding attempts are cared for by the male alone. The combination of a cold climate, giving high energetic costs of incubation and thermoregulation, and restricted foraging time due to uniparental Incubation, resulted in non-adaptive mass loss and constrained Investment of time and energy In incubation. If the incubation period is potentially energetically constrained, then behavioural mechanisms that reduce energetic costs could increase the production of young. When more energetically constrained, dotterel reduced the energetic cost of incubation by scheduling trips in conditions when the unattended eggs would have cooled more slowly and by making fewer, but longer trips. When suffering severe energetic constraint, some dotterel neglected their eggs for many hours: dotterel embryos' high chilling tolerance may have been necessary for successful uniparental incubation In a cold and unpredictable environment. Dotterel selected nest sites that allowed them to build larger nests with larger linings. Larger, better insulated nests probably decreased heat loss from the eggs and sitting parents, so reducing energetic costs during incubation. Sitting dotterel oriented into the wind, which probably reduced the disruption of their plumage and minimised their energetic expenditure on thermoregulation. In cooler conditions, dotterel changed their nest defence strategy and used energetically cheaper but probably riskier responses to simulated predators. Behaviours may be shaped under conflicting selective pressures and dotterel's management of their high energetic costs during the incubation period was constrained by egg-predation: dotterel's incubation scheduling appeared to be influenced by diurnal variation in the risk of predation and dotterel's nest defence behaviour traded-off energetic costs and the risk of predation. I declare that this thesis has been composed by myself and that it embodies the results of my own research. Where appropriate, I have acknowledged the nature and extent of work carried out in collaboration with others. This thesis presents data collected by myself over 2,212h spent in the alpine study areas from 288 days during my PhD field seasons in 1996,1997 and 1998. I also analyse some of Scottish Natural Heritage's dataset on dotterel biology collected between 1987 and 1999 by a team of fieldworkers, including myself (in Chapters 2,7 and 8).

No description available.

Bibliography: leaves 219-229. / Microfiche. / xiv, 229 leaves, bound ill. 29 cm

Typescript (photocopy) / Includes bibliographical references (leaves 223-249) / 249 leaves, [10] leaves of ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates the relationship between feed conversion efficiency and physiological variables among several lines, generations and breeds of hen fed ad libitum or on restricted amounts of feed; and, of the consequences to egg shell quality of restriction of food supplied to laying hens. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Physiology, 1982

Typescript (photocopy) / Includes bibliographical references (leaves 223-249) / 249 leaves, [10] leaves of ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates the relationship between feed conversion efficiency and physiological variables among several lines, generations and breeds of hen fed ad libitum or on restricted amounts of feed; and, of the consequences to egg shell quality of restriction of food supplied to laying hens. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Physiology, 1982

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 44-49)