Agriculture and Food Systems - Theses

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    The effect of air-drying on the level of extractable manganese and cobalt in the soil
    Zende, G. K ( 1953)
    The work presented here, was carried out to study' mainly one side of the problem, namely the slow reduction of manganese oxides by the organic matter during the process of air-drying. The other possibility - colloidal effect - needs further investigation. The effect of air-drying was studied In two alkaline soils and four acidic soils, limed to different pH. From the consideration of these results, the following conclusions can he drawn. (1) The effect of air-drying on the extractable manganese is seen only in soils with pH less than 6. (2) The effect is dependent on the amount of active manganese oxides and the amount of organic matter. (3) The, kind of organic matter and the nature of the oxide contribute to the effect of drying (but some further work is necessary.). Cobalt was included to check these factors with the assumption that it will behave as an unoxidized model for Mn. In general, there is no increase in the level of extractable cobalt after drying. Introduction of cobalt raised some new problems and an attempt was made to get some Information on the various aspects of the chemistry of, cobalt In the soil.
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    Body composition studies in the sheep
    Wardrop, Ian Donald ( 1957)
    When he was Senior Lecturer in Animal Physiology and Production at Melbourne University, Dra T.J. Robinson initiated a series of experiments concerned with the body composition of fat lambs. This study was carried out by the following team of workers under Dr. Robinson's leadership: Mr. Blair-Weste Physiology School; Dr. Binet, Statistics Department; and myself from the school of Agriculture. The aims of this study were to determine: (1) Whether the quality and conformation of a fat lamb carcass could be defined by external body and probe measurements. (2) Whether the antipyrene technique could be used to estimate the total body water in lambs and hence their body composition in terms of total waters fat, and fat free tissue. (3) What relationships might exist between the specific gravity of a lamb carcass and its fat content. (4) Whether sample joints in a lamb carcass were representative of the whole carcass in terms of total bone, muscle, and fate and therefore of total water, fat, and fat free tissue. The first part of the investigation was carried out by Drs. Robinson and ninety and I was in no way involved. The other experiments were carried out jointly by Dr. Robinson, Blair-West and myself. In October, 1953, Dr. Robinson divided 8 newly-born Suffolk cross lambs (all singles) into four similar pairs, and fed each pair on a different plane of nutrition. The lambs, which were made to grow along predetermined growth curves, were weighed fortnightly and antipyrene determinations were carried out monthly. Thus the growth curve of each lamb could be drawn and split up into its component parts - i.e. H2O, fat and fat-free tissue. All lambs were killed when they reached 80 lbs. live weight, and the carcasses deep frozen. When I joined the team, in January, 1955, the carcasses were removed from the cold store and I carried out the specific gravity determinations on them. In order to test the worth of both the antipyrene and specific gravity techniques some standard methods of estimating body composition had to be used as a comparison. It was hoped that the specific gravity of the carcass would give a measure of chemical fat content of the carcass and that antipyrene estimations would give a measure of the total body water in the live sheep. The standard technique used for assessing these estimates was a complete chemical analysis of each lamb into total water, fat protein and residue. One side of each carcass was dissected into total bone, muscle, subcutaneous and intermuscular fat. It was then possible to assess the relationships between the physical and chemical composition of the carcass and the relationships between the physical and chemical composition of sample joints in the carcass and the total carcass. I was responsible for carrying out both the carcass dissections and the chemical analysis. During the course of this work (February, l956), Dr. Robinson took up a new appointment as. Professor of Animal Husbandry at Sydney University. I remained in Melbourne to complete the work under the direction of Dr. D.E. Tribe, the newly appointed Reader in Animal Physiology and Production. The experimental work reported in this thesis is limited to that part of the study for which I was responsible. It will be appreciated therefore, that its full significance lies in its relationship to the work of the other members of the team.
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    A new virus disease of carrots : its transmission, host range, and control
    Stubbs, Lionel Leslie ( 1948)
    During 1940 commercial vegetable growers in the Melbourne market garden area requested an investigation of a disease of spring sown carrots, which had been occurring over a number of years. Summer sowings were not affected, but the failure, or partial failure, of spring sowings had made the production of this crop uneconomic, and as a result, the continuity of carrot supplies to the Melbourne market had been disrupted. The principal objects of the investigation described in this paper have been the elucidation of the factors responsible for the disease, and the development of practical disease control measures. A preliminary report of the investigation, which commenced in 1941, has been published elsewhere (Stubbs & Grieve, 1944).
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    The effect of the level of nutrition during pregnancy and lactation on the production of grazing sheep, and the interaction between levels of fertility and nutrition
    Papadopoulos, J. C ( 1956)
    The livelihood of the sheep farmer depends upon the success with which his ewes produce and rear healthy lambs. This is of particular truth in those areas where fat lambs are produced. It is well known that the production of lambs in large number and in good health depends very largely upon the standard of feeding of the ewes during pregnancy and lactation. however in most areas of the world sheep are restricted to those marginal localities in which the agriculturist finds it difficult to produce milk, eggs or vegetables. Under these conditions, the feeding of pregnant and lactating ewes becomes a task of some difficulty. Where food is in short supply it is very necessary to know at what stage of pregnancy or lactation the plane of nutrition should be raised. Thomson and Thomson (1949) have shown that in Scotland the sheep farmer should feed a supplement to his ewes during late pregnancy. Coop (1950) on the other hand has shown that under his New Zealand conditions, the supplement was best reserved until lactation has commenced. It was thought important to know the effect of different planes of nutrition on pregnant and lactating ewes under the conditions of sheep farming in South Victoria. It was for this reason that the present investigation was undertaken. In addition it was thought to be of interest to determine the interaction "if any" between the level of fertility and that of nutrition
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    An analysis of the problems of estimating the thyroid hormone level in the blood of domestic animals, and the effects of varying that level on the marketable products of such animals
    Edmonds, Brenda Morris ( 1957)
    In the field of animal husbandry it is becoming increasingly apparent that maximum efficiency of production cannot be attained without careful attention to the health of the animal, and to the balance between the animal and both the internal and external environments. For example, if artificial methods are used to increase production of milk without at the same time increasing, the feed intake the result is generally a decline in the health of the cow which may eventually lead to serious illness. Much recent research in this field has been concerned with the function and activities of specific organs rather than with the body as a whole, showing; that the factors involved in production are much more numerous and varied than was originally thought. Examples of this type of research are the intensive investigations at present being conducted into rumen activity and microflora, wool fibre growth, mammary gland function, reproductive activity and the role of various endocrine glands in production. Of the endocrine glands, apart from those directly concerned in reproduction, the one most studied has been the thyroid which has been shown to play an important part in practically all spheres of animal production so far investigated. It was the aim of this experiment to establish a method for determining thyroid activity which would then allow us to investigate the relationship between this activity and various body processes in the normal animal. In the normally functioning animal the thyroid serves chiefly as a homeostatic mechanism maintaining the body functions at a steady level of activity and, to a certain extent, controlling the response of the body to changes in the external environment. Its effects are more apparent when the thyroid activity is altered in any of the many ways to be considered later. The lowering of the thyroid hormone output produces an animal with typical symptoms - low Basal Metabolic Rate, low body temperature, low reproductive capacity, decreased growth and development in young animals, increased fat deposition, sluggishness, drying and thickening of the skin and falling hair. On the other hand the hyperthyroid animal shows an. increased Basal Metabolic Rate, high body temperature, leanness, restlessness and, in some cases, protruding eyes. These facts have recently been put to practical agricultural use. Raising the thyroid output leads to a significant increase in growth rate, milk yield and egg production. Lowering; the level has proved a successful method of fattening pigs and fowls for meat production. These aspects are dealt with in the review of literature.
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