The protein requirements of the South African abalone, Haliotis midae
- Authors: Shipton, Thomas A
- Date: 2000
- Subjects: Abalones -- Nutrition Abalones -- Digestion
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5314 , http://hdl.handle.net/10962/d1005159
- Description: The potential to reduce feed formulation costs by the replacement of existing proteinsources in artificial feeds for Haliotis midae was assessed. A comparison between the efficacy of the direct method and chromic oxide marker techniques in determining apparent protein digestibility coefficients, revealed that while the former was not a suitable methodology for use with this species, the latter produced replicable and reliable results. It was established that the chromic oxide marker is inert, is not absorbed by the abalone, does not interfere with the digestive processes and moves through the intestine at the same rate to the protein. However, as this method was time consuming and expensive to implement, a multienzyme pH-stat in vitro protein digestibility technique using a three enzyme system was employed to rapidly assess the protein quality of 34 protein sources. The efficacy of the technique was established by correlating the in vitro digestibility estimates with in vivo digestibility coefficients obtained using the chromic oxide marker technique. The highest degree of in vivo predictability was attained when protein sources were separated according to origin, and significant correlations between either animal (r²=0.89, P<0.004) or plant (r²=0.79, P<0.04) protein sources were found. The effect of animal size on the qualitative protein requirements of two size classes of H.midae was assessed by feeding 12 isonitrogenous and isoenergetic single protein diets to juvenile and young adult animals (10-20 and 40-50mm shell length). The criteria for protein source selection were their bioavailability as determined using the pH-stat in vitro digestibility technique, and their cost and availability within South Africa. The protein sources identified for the trial comprised four fishmeals, casein, spirulina, abalone viscera silage, brewery waste, torula yeast, carcass, sunflower and cotton meals. The results indicated that in terms of growth and feed efficiency, the fishmeals and spirulina were the most suitable candidates as primary protein sources in formulated feeds for H.midae, and with the exceptions of the carcass meal and brewery waste, the remaining protein sources demonstrated promise as partial primary protein source replacements. The smaller size class of abalone displayed significantly reduced growth, feed and protein efficiency than their larger counterparts. In terms of feed conversion and growth response, two-way analysis of variance revealed significant interactions between protein source and animal size, suggesting that qualitative differences exist between the dietary protein requirements of the juvenile and young adult abalone. The commercial implication of thisfinding was discussed. An evaluation was undertaken to determine the effects of the partial and total replacement of dietary fishmeal with selected plant protein sources on growth and nutritional indices of juvenile H.midae. A commercial “Abfeed” formulation in which 100% of the protein component comprised LT-fishmeal was employed as a control. Fifteen isonitrogenous experimental diets were formulated in which the LT fishmeal was substituted at either 10, 15, 30, 50, 75 or 100% with either spirulina, semolina, ground maize, torula yeast, soya, sunflower or corn gluten meals or combinations thereof. No significant differences were found in the growth rates between the control diet and those diets in which 30% of the fishmeal component had been replaced by either soya, sunflower meal, or torula yeast. In addition, 50% of the fishmeal component could be substituted with either soya meal or spirulina without affecting growth. Replacement of either 75 or 100% of the fishmeal had a significant negative affect on growth. Pearson product moment correlations between dietary lysine levels and either growth rates or protein efficiency ratios revealed positive correlations (r=0.77, P=0.0005; r=0.52, P=0.04 respectively) suggesting that lysine may have been the first limiting amino acid in these diets. Carcass analysis revealed that dietary protein source had no significant effect on body composition. An assessment of the dietary arginine requirement of juvenile H.midae using whole proteins to supply graded levels of dietary arginine did not promote a growth response. It was concluded that arginine is probably not the first limiting amino acid in formulated feeds for H.midae. An assessment of the dietary lysine requirement of juvenile H.midae using two micro-encapsulation techniques (gelatin/acacia colloid or cellulose acetate phthalate) was not successful. The efficacy of the encapsulation techniques were established and an assessment of the degree of lysine supplementation undertaken. Failure of the crystalline lysine enriched diets to promote growth suggests that the prospects for using crystalline amino acids in essential amino acid requirement studies in H.midae is low. The results of the present study indicate that the prospects for replacing fishmeal with cheaper alternative protein sources in artificial feeds for H.midae is promising. Furthermore, while the technical difficulties such as the determination of the essential amino acid requirements of the abalone precluded the application of “least cost” programming, the prospects for its future application are promising.
- Full Text:
- Date Issued: 2000
- Authors: Shipton, Thomas A
- Date: 2000
- Subjects: Abalones -- Nutrition Abalones -- Digestion
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5314 , http://hdl.handle.net/10962/d1005159
- Description: The potential to reduce feed formulation costs by the replacement of existing proteinsources in artificial feeds for Haliotis midae was assessed. A comparison between the efficacy of the direct method and chromic oxide marker techniques in determining apparent protein digestibility coefficients, revealed that while the former was not a suitable methodology for use with this species, the latter produced replicable and reliable results. It was established that the chromic oxide marker is inert, is not absorbed by the abalone, does not interfere with the digestive processes and moves through the intestine at the same rate to the protein. However, as this method was time consuming and expensive to implement, a multienzyme pH-stat in vitro protein digestibility technique using a three enzyme system was employed to rapidly assess the protein quality of 34 protein sources. The efficacy of the technique was established by correlating the in vitro digestibility estimates with in vivo digestibility coefficients obtained using the chromic oxide marker technique. The highest degree of in vivo predictability was attained when protein sources were separated according to origin, and significant correlations between either animal (r²=0.89, P<0.004) or plant (r²=0.79, P<0.04) protein sources were found. The effect of animal size on the qualitative protein requirements of two size classes of H.midae was assessed by feeding 12 isonitrogenous and isoenergetic single protein diets to juvenile and young adult animals (10-20 and 40-50mm shell length). The criteria for protein source selection were their bioavailability as determined using the pH-stat in vitro digestibility technique, and their cost and availability within South Africa. The protein sources identified for the trial comprised four fishmeals, casein, spirulina, abalone viscera silage, brewery waste, torula yeast, carcass, sunflower and cotton meals. The results indicated that in terms of growth and feed efficiency, the fishmeals and spirulina were the most suitable candidates as primary protein sources in formulated feeds for H.midae, and with the exceptions of the carcass meal and brewery waste, the remaining protein sources demonstrated promise as partial primary protein source replacements. The smaller size class of abalone displayed significantly reduced growth, feed and protein efficiency than their larger counterparts. In terms of feed conversion and growth response, two-way analysis of variance revealed significant interactions between protein source and animal size, suggesting that qualitative differences exist between the dietary protein requirements of the juvenile and young adult abalone. The commercial implication of thisfinding was discussed. An evaluation was undertaken to determine the effects of the partial and total replacement of dietary fishmeal with selected plant protein sources on growth and nutritional indices of juvenile H.midae. A commercial “Abfeed” formulation in which 100% of the protein component comprised LT-fishmeal was employed as a control. Fifteen isonitrogenous experimental diets were formulated in which the LT fishmeal was substituted at either 10, 15, 30, 50, 75 or 100% with either spirulina, semolina, ground maize, torula yeast, soya, sunflower or corn gluten meals or combinations thereof. No significant differences were found in the growth rates between the control diet and those diets in which 30% of the fishmeal component had been replaced by either soya, sunflower meal, or torula yeast. In addition, 50% of the fishmeal component could be substituted with either soya meal or spirulina without affecting growth. Replacement of either 75 or 100% of the fishmeal had a significant negative affect on growth. Pearson product moment correlations between dietary lysine levels and either growth rates or protein efficiency ratios revealed positive correlations (r=0.77, P=0.0005; r=0.52, P=0.04 respectively) suggesting that lysine may have been the first limiting amino acid in these diets. Carcass analysis revealed that dietary protein source had no significant effect on body composition. An assessment of the dietary arginine requirement of juvenile H.midae using whole proteins to supply graded levels of dietary arginine did not promote a growth response. It was concluded that arginine is probably not the first limiting amino acid in formulated feeds for H.midae. An assessment of the dietary lysine requirement of juvenile H.midae using two micro-encapsulation techniques (gelatin/acacia colloid or cellulose acetate phthalate) was not successful. The efficacy of the encapsulation techniques were established and an assessment of the degree of lysine supplementation undertaken. Failure of the crystalline lysine enriched diets to promote growth suggests that the prospects for using crystalline amino acids in essential amino acid requirement studies in H.midae is low. The results of the present study indicate that the prospects for replacing fishmeal with cheaper alternative protein sources in artificial feeds for H.midae is promising. Furthermore, while the technical difficulties such as the determination of the essential amino acid requirements of the abalone precluded the application of “least cost” programming, the prospects for its future application are promising.
- Full Text:
- Date Issued: 2000
The psychological role of homoeroticism in the spiritual growth of priests: a study of individuation processes and homoerotic sexualities
- Authors: Taute, Harold Graeme
- Date: 2000
- Subjects: Homosexuality -- Psychological aspects Homosexuality -- Religious aspects -- Christianity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3069 , http://hdl.handle.net/10962/d1002578
- Description: The study explored the psychological role of homoeroticism in the spiritual growth of priests, using Grounded Theory and James Fowler’s stages of faith development as the basis for the research methodology. Three Anglican priests were interviewed using a semi-structured interview format. The research interview combined Fowler’s Faith Development Interview Guide and a semi-structured interview in order to ascertain the priests’ level of spiritual development, as well as to explore their experience of the homoerotic component to their sexuality, and its influence on their spiritual growth. The interviews and iterative analysis focussed on four major questions: (1) Are priests who experience and actively work at integrating the homoerotic aspect to themselves assisted thereby in their spiritual growth, and if so, how might this be accounted for?; (2) Following Fowler’s model of spiritual development, what processes characterise each priest’s approach to meaning-creation in their lives?; (3) Following Fowler’s model, can the psychological work of engaging with and accepting homoeroticism be conceived of as serving an initiatory function in the emergence of new processes of meaning-creation?; (4) What role does homoeroticism serve in the spiritual growth of priests? The interpretative phase consisted of three stages. A grounded theory analysis of each interview was undertaken, developing a model for understanding the role of homoeroticism in spiritual growth. In the second stage, the priest’s level of spiritual development was ascertained, using Fowler’s Faith Development Guide. The third stage linked each participant’s level of spiritual development (in Fowler’s terms) with their core stories regarding experiences, meanings, and roles of homoeroticism. Finally, an integrative theory of the role of homoeroticism in spiritual growth was developed, using Jungian and post-Jungian theory as a basis for the discussion. The results suggested that homoeroticism did not play any role in spiritual growth and individuation separate to the manner in which it was experienced as having been constructed by society and the Church, and separate to the manner in which each priest in the study expressed, experienced, or engaged with it. In this context the experience of homoeroticism appeared to play a diversity of roles, including representing the collective and personal shadow, the archetypal anima/animus, the archetypal puer/senex constellation, the transcendent function, and thereby, as an expression of these roles, contribute to the emergence of new processes of meaning-creation in the spiritual growth and individuation of priests.
- Full Text:
- Date Issued: 2000
- Authors: Taute, Harold Graeme
- Date: 2000
- Subjects: Homosexuality -- Psychological aspects Homosexuality -- Religious aspects -- Christianity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3069 , http://hdl.handle.net/10962/d1002578
- Description: The study explored the psychological role of homoeroticism in the spiritual growth of priests, using Grounded Theory and James Fowler’s stages of faith development as the basis for the research methodology. Three Anglican priests were interviewed using a semi-structured interview format. The research interview combined Fowler’s Faith Development Interview Guide and a semi-structured interview in order to ascertain the priests’ level of spiritual development, as well as to explore their experience of the homoerotic component to their sexuality, and its influence on their spiritual growth. The interviews and iterative analysis focussed on four major questions: (1) Are priests who experience and actively work at integrating the homoerotic aspect to themselves assisted thereby in their spiritual growth, and if so, how might this be accounted for?; (2) Following Fowler’s model of spiritual development, what processes characterise each priest’s approach to meaning-creation in their lives?; (3) Following Fowler’s model, can the psychological work of engaging with and accepting homoeroticism be conceived of as serving an initiatory function in the emergence of new processes of meaning-creation?; (4) What role does homoeroticism serve in the spiritual growth of priests? The interpretative phase consisted of three stages. A grounded theory analysis of each interview was undertaken, developing a model for understanding the role of homoeroticism in spiritual growth. In the second stage, the priest’s level of spiritual development was ascertained, using Fowler’s Faith Development Guide. The third stage linked each participant’s level of spiritual development (in Fowler’s terms) with their core stories regarding experiences, meanings, and roles of homoeroticism. Finally, an integrative theory of the role of homoeroticism in spiritual growth was developed, using Jungian and post-Jungian theory as a basis for the discussion. The results suggested that homoeroticism did not play any role in spiritual growth and individuation separate to the manner in which it was experienced as having been constructed by society and the Church, and separate to the manner in which each priest in the study expressed, experienced, or engaged with it. In this context the experience of homoeroticism appeared to play a diversity of roles, including representing the collective and personal shadow, the archetypal anima/animus, the archetypal puer/senex constellation, the transcendent function, and thereby, as an expression of these roles, contribute to the emergence of new processes of meaning-creation in the spiritual growth and individuation of priests.
- Full Text:
- Date Issued: 2000