School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemAn evaluation of the role of extension in the Australian pig industry( 1978)Australian agriculture is adjusting to changes in technology, economic circumstances and markets. Extension services as much as the producers' need to change in response to changing industry needs, market trends and consumer demands. There has been much discussion on the problems that these changes present for extension, but none on the basis of empirical research or social science theories. A research program was developed to define the changes taking place in the structure and organisation of the Australian pig industry, and to identify the implications of these changes for pig producers and for extension agencies such as State Departments of Agriculture. The conclusion drawn from the review of the industry situation and from a Delphi survey of 10 experts in the pig industry was that the industry will become more technical and commercialised requiring continual adaptation by the producers to technical and economic changes in order to maintain and increase production efficiency. The survey results showed that a degree of assistance from research and extension was expected by producers to help them maintain and improve production efficiency. Based on the Theory of Personal Constructs, Kelly (1955) an interactive psychological testing procedure known as the Repertory grid was used to record producers' and extension officers' perceptions of each other and of extension services. Twenty pig industry officers, 16 non extension users, 20 extension users and 16 large commercial producers were interviewed. Separate analyses were carried out on the grids of individual subjects, providing profiles of constructs typically used by the subjects in relating to and evaluating people. The results clearly identified the constructs which farmers used in relating to extension advisers and advice. In general, all groups of subjects tended to stereotype people with whom they associated. Combination of both the results within subject groups revealed evidence of commonality within and between the groups in their perceptions. The extension officers saw themselves as progressive and useful while a large number of the producers saw them as theoretical and irrelevant. Extension users held favourable attitudes towards professional agricultural advisers, while large commercial producers and non extension users criticised them on the grounds that they were difficult to communicate with and lacking practical experience. As a group, extension officers were not aware of the questioned relevance of their advice nor of the difficulty experienced by producers in communicating with them. Owing to their practical background and shared experiences, all producers saw other producers as useful and as the most relevant source of advice. The roles they expect him to perform and the characteristics that producers expect from a professional extension adviser have been identified and their implications for the extension officer are discussed. The most obvious implications of the findings are that extension advisers fail to establish the relevance of information within the farmers' context of what is relevant. Based on the findings of the research the theory is proposed that extension programmes will be most successful when producers and extension workers share common perceptions of relevant problems. A philosophy and practice of extension is proposed to meet the farmers' own perception of needs. The interpretation of the results in terms of Personal Construct theory leads to the development of the model of human behaviour, that is, "man as an actor" instead of "man as something being acted upon". A philosophy of extension is developed based on the belief that extension can only be successful if it provides what farmers want. The philosophy states that extension should provide a helping role by facilitating, developing and supporting "man the actor" without dominating or controlling his actions. A practice of extension operating within the boundaries of the proposed new philosophy is developed from the helping relationship model of Carkhuff (1969). The goals of extension are defined as exploration, understanding and action which lead directly to the need for skills which are defined as the "interface skills" of attending, responding, personalising and initiating. The need for and the nature of extension training to provide extension officers with "interface skills" is discussed.
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ItemSocial and sexual factors affecting reproduction of the domestic boar( 1978)This thesis describes the results of work in three general areas; (i) the influence 0f the social environment during rearing and after puberty on the sexual behaviour of the boar, (ii) the role of the courting behaviour of the boar in his reproductive performance, and (iii) the influence of sexual stimulation on the spermatozoan output of the boar. The major portion of the work relates to the importance of the social environment. Boars reared from three weeks of age in the absence of visual and physical contact with pigs had markedly lower copulatory performance and level of courting activity compared with those reared from three weeks in either an all-male or mixed-sex group. Lack of physical contact with pigs during rearing was responsible for approximately 70% of this depression in copulatory performance. The copulatory performance of boars reared from 12 weeks of age in the absence of visual and physical contact with pigs was considerably less than that of boars reared in an all-male group, but the difference was not significant. Boars reared from three or 12 weeks- of age individually in adjacent wire-mesh pens had similar copulatory performance to that of group-reared boars. However, an apparently important feature of courting behaviour, 'nosing activity', was significantly reduced for those boars reared from three weeks individually in adjacent wire-mesh pens. These data were interpreted as evidence of the importance of social contact, particularly physical contact with boars or gilts, during rearing on the level of sexual behaviour of the boar. In addition to the social environment during rearing, the social environment after puberty was demonstrated to have a dramatic influence on the level of sexual behaviour of the boar. Isolation of post-pubertal boars from female pigs for six weeks significantly reduced their copulatory performance and level of courting activity. The stimuli received from the presence of sexually receptive or sexually non-receptive female pigs were equally capable of maintaining the level of sexual behaviour of the boar. Two experiments conducted at a commercial piggery revealed the importance of the courting behaviour of the boar on reproductive performance. A significant positive correlation was found between the observed level of nosing activity during courting and the conception rate record of the boar. The proposal that the nosing activity of the boar may stimulate one or more physiological mechanisms leading to fertilisation in the sow is supported by the results of the second experiment. Brief courting of sows by a boar prior to artificial insemination significantly increased the farrowing rate and litter size of group-housed sows. Finally, sexual stimulation of boars prior to semen collection significantly increased the number of spermatozoa . in the sperm-rich fraction of the ejaculate. The technique of sexual stimulation of the boar involved either allowing the boar a false mount and then briefly restraining him or allowing the boar to observe a semen collection. The former technique failed to maintain a significant increase in the yield of spermatozoa from the sperm-rich fraction over a six-week collection period. Prostaglandin F2a, which may be involved in the mechanism by which sexual stimulation increases the number of spermatozoa in the short term, was also studied. Administration of 20 mg of PGF2a 30 minutes before collection significantly increased the number of spermatozoa in the sperm-rich fraction of the ejaculate. The experiments of this thesis demonstrate that sexual and social factors have a major influence on the reproduction of the domestic boar.
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ItemEstimation of the available amino acid contents of feeds for pigs with Tetrahymena pyriformis w( 1973)Experiments were conducted to evaluate the usefulness of the Tetrahymena assay for predicting the available amino acid content of feeds for pigs. In collaborative studies the Tetrahymena lysine values were also compared with values from the Silcock technique for a series of feeds and attempts were made to evaluate which technique was more applicable to pigs. The pig experiments were conducted with pigs fed individually once daily during the 20 to 45 kg growth phase. Pig response was assessed in terms of live-weight gain, feed conversion efficiency and carcass lean as estimated by joint dissections. 1) The 4-day incubation period for the assay of proteins by Tetrahymena as recommended by Stott and. Smith (1966) was found to be adequate for buttermilk powder but not for fish meal or meat and bone meal. By extending the incubation of the latter two meals to 7 days, complete hydrolysis was achieved. Experiments with pigs fed diets formulated with values from either the 4-day or the 7.-day incubation periods for fish meal and meat and bone meal indicated that values obtained with the Tetrahymena assay after complete hydrolysis of the meals were more applicable to pigs than were those estimated after 4-days. 2) For cereals a 10-day incubation period for estimates of lysine and tryptophan with Tetrahymena was found necessary for maximum hydrolysis, and there was good agreement between these values and the response in pigs. 3) There was close agreement between Tetrahymena and Silcock estimates for lysine in samples of soyabean meal that were autoclaved for varying times. In a pig experiment the additions of lysine, methionine and tryptophan to diets containing the autoclaved soyabean meal restored only 43% of the effects of the heat damage. 4) This raised the question as to whether the supplements of free amino acids had been efficiently utilised by the pigs. A pig experiment was conducted to examine the effect of feeding a ration containing free lysine either once daily or in six equal portions at three hourly intervals. The results indicated that only 43% of the free lysine was utilised with once daily feeding relative to the frequent feeding regime. Thus the inability of the amino acids added to the autoclaved soyabean meal to compensate for the effects of heat damage may have been due to inefficient utilisation of the added amino ' acids by the pigs and not to inapplicability of the estimates of heat damage. 5) The amount of protein used in the Tetrahymena assay was found to govern the subsequent hydrolysis of the protein. Attempts to promote more vigourous hydrolysis of small amounts of protein by increasing the amount of inoculum were unsuccessful. Vigourous hydrolysis of the protein was obtained by the addition of 0.25 mg L-lysine-HC1 to each assay; this stimulated the initial growth of Tetrahymena, then vigourous hydrolysis resulted. 6) The rate of release of lysine from protein concentrates by Tetrahymena varied. Buttermilk powder and skim milk powder required 2 days, peanut meal 3 days, soyabean meal 4 days, safflower meal 5 days, rapeseed meal 6 days and fishmeal and meat meal 7 to 8 days. Free lysine was utilised within 4 days. 7) The Tetrahymena and Silcock lysine values for different protein concentrates showed no consistent pattern. For soyabean meal the Tetrahymena lysine values were greater than the Silcock values, for peanut meal the estimates were similar, and for the other proteins the Tetrahymena values were lower than the Silcock values. This was particularly so for a meat meal and rapeseed meal where the Tetrahymena values were approximately half the Silcock estimates. 8) An attempt was made to supplement cereal-based diets with protein-bound lysine to achieve diets of similar lysine content; both the Tetrahymena and the Silcock values were used to compute the amount of supplementary protein needed. Diets formulated according to these two values were then fed to pigs in an attempt to decide which value was the better indicator of lysine availability to pigs. This experiment proved inconclusive as factors other than lysine appeared to have influenced the results. This aspect of the comparison of the two methods of assay needs to be examined using feeding trials on a larger scale to eliminate these complicating factors. 9) In Appendix 1, the modifications made to the Tetrahymena assay to allow complete hydrolysis of proteins are Outlined.