School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemThe 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( 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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ItemBark disorders and manganese nutrition of some fruit trees in the Goulburn Valley( 1961)Some Delicious apple trees growing in the Goulburn Valley and adjacent areas show "measles", an internal bark necrosis with elevated pustules distributed over the bark surface. Wood which is one or more years old is affected. The pustules increase in number and size as the disorder becomes more severe. In the cortex underneath the bark epidermis, necrotic spots are found in great numbers, being largest beneath the epidermal elevations. In severe cases, cracking and splitting of the bark occurs, mainly on older wood; the affected trees have fewer and smaller leaves than normal; twigs and limbs die back; and eventually the whole tree may die. Another bark disorder, known as "papery bark", is fairly common on Josephine pears in the Goulburn Valley. The symptoms are an internal bark necrosis with cracking and rolling back of the bark epidermis on shoots and twigs one or more years old. The symptoms of a further disorder, known locally as "leaf spotting are more severe on these trees affected with "papery bark", and in addition fruit on such trees or limbs shows more "russeting" than is normal. Die-back of shoots and limbs often follows. The cause of these nutritional disorders, "bark measles" on Delicious apples and "papery bark" on Josephine pears, was investigated. The analysis of fresh tissues showed increased amounts of manganese in leaves, fruit and, bark of affected apple trees and in the leaves, bark, buds and fruit of affected pear trees. To demonstrate that excess uptake of manganese was the cause of these disorders, hydrated manganese sulphate was injected into trees of healthy appearance showing low manganese content in their fresh tissues. After this injection, disorders similar to "bark measles" and "papery bark" were produced on apples and pears respectively. Soil acidification with chemicals in the field and soil waterlogging in pots also produced "papery bark" on pears, while soil waterlogging in pots produced "bark measles" on apples. Analysis showed increased amounts of soluble manganese in treated soils and in the tissues of affected plants growing on treated soils. Laboratory trials with soils from orchards, both healthy and with manganese toxicity (hereafter called "toxic soils"), showed that drying, heating and waterlogging, especially at temperatures of 20 degree Celsius or more, also contribute to the release of high amounts of soluble manganese. These trials showed the importance of moisture conditions and pH in the recovery of toxic soils.
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ItemNutritional studies of the young lamb( 1967)This thesis is based on original research work in a subject approved by the Faculty of Agriculture and is submitted under regulation 3.28 Section 6(a) of the conditions relating to the degree of Master of Agricultural Science. The experiments presented have been published in the Australian Journal of Experimental Agriculture and Animal Husbandry or in the Proceedings of the Australian Society of Animal Production. They were conducted while the author was a member of the Victorian Department of Agriculture which provided the facilities for this work. The first chapter of the thesis is a review of the literature on the digestibility of milk and solid food by the young ruminant - more specifically the calf and the lamb. The second chapter describes two experiments on the apparent digestibility of ewes milk and dried pasture by young lambs and the third chapter comprises two experiments relating to the effect of milk intake on the pasture consumption of lambs. The fourth chapter reports observations on the diet selected by grazing lambs in relation to older sheep. I was responsible for the design of this experiment, was actively associated with the field work and prepared the manuscript for publication. The fifth chapter is a paper on the effect of nutritional restriction during pregnancy on the reproductive performance of crossbred ewes and the subsequent growth of their lambs. The sixth chapter provides summaries of the experiments presented.
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ItemEffects of some management factors on sheep and wool production( 1970)It is difficult to be precise about the importance of the contributions made by the many people involved in this work. On a government research station and on private farms, field experiments inevitably involve many people. However, in each chapter presented in this thesis I made a major contribution in the planning, supervising and conducting of the experiment and in preparation of the results for publication. Where authorship has been shared, this is indicated at the beginning of each chapter. Some indication of the relative importance of contributions to this work is as follows:- Chapter I: The experiments were done on two sites, and at one of them Katamitite) I was directly responsible for the work. Chapters II, III: This work undertaken jointly with Mr. J.G. Bath, Chapters IV, V: This work was my responsibility. Chapter VI: The observations on sheep were my responsibility whereas those on pastures were the responsibility of Mr. J. Avery and Mr. I. Cameron. I prepared the manuscripts for chapters I to V and contributed to the preparation of that for chapter VI.
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ItemUtilization of protein and energy in growing lambs( 1970)Extensive pasture improvement throughout large areas of Australia in recent years has emphasized the need for more efficient methods of pasture utilization. This has been achieved to some extent by an increase in sheep stocking rates. However, the benefits from high stocking rates are far greater when used for the production of wool from dry sheep than when applied to breeding flocks producing prime lambs. Results from many experiments with wethers (Arnold & McManus, 1960; Drake & Elliott, 1963; Bishop, Birrell & Tew 1966; Morley & Ward, 1966) indicate that as stocking rate is increased total wool production per acre increases substantially. The relationship between total wool production and stocking rate is curvilinear (Bishop et al., 1966) and although the stocking rate which results in the maximum production per acre is higher than that which achieves the greatest economic return (Lloyd, 1966),a considerable increase in farm income can be obtained when the stocking rate of wethers is raised above conventional levels (Chisholm, 1965). The improvement in pasture utilization when wethers are grazed at high stocking rates is brought about by an increase in competition between individual sheep and the consumption of much of the poorer quality and damaged pasture which is otherwise rejected. Increasing competition eventually results in a reduction in feed intake with a concomitant lowering of production. However, the adverse effects of a reduced intake are less for wool growth than for most other forms of production. For example, the results of Bishop et al. (1966) indicate that wool growth of Corriedale - Polwarth cross wethers will continue at a rate of approximately 14 g/day inspite of the fact that feed intake was insufficient to produce a gain in live-weight. A reduction in feed intake has more serious repercussions in a breeding flock. A nutritional stress on the ewe can lead to (a) low live-weight at mating with its effect on ovulation (Edy, 1968) and lambing percentage (Coop, 1962) , (b) small live-weight gains during gestation with low birth weights of lambs from multiple births (Wallace, 1948) and high perinatal mortality (Alexander, 1962), (c) poor lactation and reduced lamb growth rates (Wallace, 1948). The presence of lambs accentuate the decline in food availability and as a result of the low intake of both milk and pasture the lambs grow poorly. Arnold and Bush (1962) found that meat production from a prime lamb flock did not increase when stocking rates were raised from 4 to 7 ewes per acre. In a more recent study (G.W. Arnold, A Axelsen & M.E. Bourke, 1965 - personal communication) it was found that as the ewes were increased from 5 to 7 per acre the number of lambs reared remained constant at 6.2 per acre, but the meat production declined. Many prime lamb producers in southern Australia have attempted to increase stocking rates, but, poor growth of lambs has generally resulted in a large percentage of them remaining unfattened at the end of the period of pasture growth. These lambs are often carried through to the following autumn and further reduce the feed available in the winter. The poor response in meat production associated with increased stocking rates was considered to be of sufficient importance for the Reserve Bank of Australia to provide finance to investigate "the problems of high stocking rates in the prime lamb industry". It seemed logical that the production of meat may be improved if the competition between the ewes and lambs could be reduced. The most common methods by which this is done is to either creep graze or early wean the lambs, thereby giving them access to more pasture of high quality. The results of several studies in England (Spedding & Large, 1959; Dickson, 1959) and Tasmania (Jefferies, Dreaver & Wilson, 1961) suggest that creep grazing systems do produce faster growth rates in lambs when stocking rates are high. However, limited evidence from the Australian mainland (Arnold & Bush, 1962; Fletcher & Geytenbeek, 1968) indicates that the creep feeding of pasture is not advantageous and that the creep feeding of lucerne produces only slight improvements in growth rates. Lambs weaned at 2 to 3 weeks of age can survive at pasture, but their growth is poor (Spedding, Large & Brown, 1961). Wardrop, Tribe & Coombe (1960) found that lambs weaned at 7 weeks of age could grow as well as unweaned controls, but that their response was sensitive to the quality and quantity of feed. However, the results of Cannon & Bath (1967) indicate that, in conditions typical for southern Australia, stocking rates must be raised above 9.6 lambs per acre before any advantage in meat production can be obtained by weaning lambs at 10 weeks of age. Therefore, it seemed that the early weaning of lambs at pasture would not greatly improve production from prime lamb when high stocking rates were used. Because the response to both early weaning and creep feeding was dependent upon the quality and quantity of the pasture, it was reasoned that these systems may be more successful if the lambs were given concentrate diets formulated to meet their nutrient requirements. However, a survey of the literature revealed that there was a dearth of information on the nutrient requirements of lambs and that many recommendations were contradictory. Because concentrate diets which would satisfy the nutrient requirements of lambs could not be formulated with confidence, the major portion of this thesis has been concerned with determining the protein requirements of young, meat producing lambs.
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ItemThe nutrition of deciduous fruit trees in Victoria( 1959?)There are few areas in the world where deciduous fruit growing is carried out over such a wide range of soils and climatic conditions as in Victoria, ranging from highly alkaline, calcareous soils under a dry, semi-desert clime to podsolic, acid soils of the temperate and rain-swept highlands. No wonder then that a wide variety of nutritional disturbances can occur on fruit trees in this state, and this work deals with their occurrence and effects, and with laboratory and field trials which search for their treatment.