School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemVegetative and sheep production on a semi-arid Danthonia caespitosa (Gaudich) -Stipa variabilis (Hughes) grassland in response to fertilizers and deferred grazing( 1977)The initial and residual effects of nitrogen and phosphorus fertilizers applied over four consecutive years and gypsum applied once only, were assessed on a Danthonia caespitosa - Stipa variabilis grassland, growing on the semi-arid Riverine Plain of south-eastern Australia. The treatments were combined factorially. The residual effects were assessed over a five-year period from when the fertilizers were last applied. Totals of 155 and 310 kg ha-1 of N, 100 and 200 kg ha-1 of P, and 3.34 and 6.68 tonne ha-1 of CaSO4.2H20 had been added. Seasonal production of total dry matter and individual species, and nitrogen and phosphorus contents of the plant tops, were measured. A simultaneous, but separate, study was made over five years of the effects of nitrogen and phosphorus fertilizers and deferred spring grazing on the bodyweight and wool production of Merino wether weaners grazing a D. caespitosa - S. variabilis grassland at three stocking rates. Seasonal forage availability, botanical composition of forage, bodyweight and wool growth of sheep, were measured. Two years after grazing treatments ceased, and three years after the final addition of fertilizer, further measurements were made on the vegetation. In the first study, during the four years of fertilizer application, forage production increased in response to the additives in years in which the annual rainfall varied from well below to near average. They accentuated the normal pattern of a spring peak, but also gave lesser increases in production in winter and autumn. Summer production was not measured because of the absence of effective summer rainfall. Nitrogen and phosphorus fertilizers and gypsum all contributed to the increased production, and the combination of the three additives produced the greatest yield. Over all seasons the yield of grassland treated with nitrogen plus phosphorus plus gypsum averaged 250 per cent of the control, or approximately 1,500 kg ha-1. The main contributors to increases in yield were D. caespitosa, S. variabilis, annual herbs, and legumes. The perennial grasses were particularly favoured by nitrogen fertilizer whereas the yield of legumes was suppressed. The yield of legumes increased greatly in response to phosphorus fertilizer. With the exception of two species, all plants which increased in yield are acceptable to sheep. Nitrogen and phosphorus contents were above the minimum requirements for domestic herbivores. The study of the residual effects revealed that the increase in dry matter production in response to nitrogen ceased one year after the last application of nitrogen fertilizer. After five years, grassland which had received 200 kg ha-1 of phosphorus and 6.68 tonne ha-1 of gypsum yielded 6,500 kg ha-4 of dry matter, compared with 1,300 kg ha-1 in the absence of fertilizers and gypsum. Legume growth was still suppressed five years after nitrogen fertilizer had been applied, whilst legumes increased production greatly in response to the previous phosphorus and phosphorus-gypsum treatments. Nitrogen content of the herbage averaged 2.1 per cent four years after the previous high level phosphorus treatment, compared to 1.6 per cent with the control after four years. It was unaffected by previous nitrogen fertilizer. Phosphorus content was reduced for the first three years after nitrogen fertilizer was last added, but was increased by phosphorus fertilizer to 0.28 per cent, compared with 0.18 per cent on the control, four years after phosphorus fertilizer was last added. Soil moisture characteristics, and total soil nitrogen and carbon showed no differences between treatments. The Truog phosphorus in the soil under the high phosphorus level decreased from 103 ppm to 53 ppm, compared to the unaltered control level of 7 ppm over the five year period. In the grazing experiment there were very few differences in plant and animal response between the continuously and deferred grazing systems. Forage availability increased on fertilized grassland at all stocking rates by up to 50 per cent. D. caespitosa, S. variabilis, perennial chenopods, and annual herbs contributed to the increase in forage present. Medicago polymorpha became prominent on all fertilized grassland. At 2.0 and 2.7 sheep ha-1 without fertilizer, and 2.7 sheep ha- 1 with fertilizer, the relative contribution by the more palatable species decreased and EriochIamys behrii increased greatly. After grazing treatments ceased, this trend was reversed. Sheep bodyweight and wool growth rates were increased on fertilized grassland. In September 1971, at 2.0 sheep ha-1, the bodyweights of sheep on unfertilized and fertilized grassland were 35.0 and 45.2 kg, respectively, and the clean fleece weights were 3.2 and 4.3 kg per sheep, respectively. Animal production from this grassland can be increased with the addition of fertilizer to the grassland and by increasing the stocking rate by about 50 per cent above the district average of 1.2 sheep per hectare.
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ItemMeasuring and improving work performance in milking systems( 1977)Milking represents 40-50% of the total labour input into Australian dairy farms. Unless this work input can be reduced, the job of milking will remain a major limitation to improvements in the efficiency of dairyfarming. The main aim of the field study reported in this thesis was to study the milking and cleaning performance of 15 of the 24 rotary milking systems operating in Australia in the Spring of 1973. Elements of the work routine time were analysed to measure: (a) the relative effects on milking throughput of alternative shed designs, operating systems and types of automation; (b) the relative influence of yard design, shed type, and the operator, on the ease and speed of cow movement from the cowyard onto the rotary platform; and (c) the labour requirements and relative effectiveness of different cleaning systems. Measurements were made at one evening milking and the following morning milking at each farm by 2, 3 or 4 observers, using multi-channel event recorders, stop watches and. recording sheets. Although changes in the element times of the work routine occurred as milking progressed, the labour productivity '(cows milked per man hour) did not change significantly during milking in the group of rotaries studied. Labour productivity was lower at morning milkings than at evening milkings. Productivity increased with increasing number of milking units per operator and, to a lesser extent, with the degree of mechanisation used. The time taken to move cows onto the rotary platforms increased towards the end of milking. The operators increased involvement in cow movement later in milking was partly compensated for by a decrease in his idle time. Operators rated as good, cowmen spent less time encouraging, forcing or assisting cows onto the platform than those operators rated as below average cowmen. Cows defecated less on "turnstyle" type rotary platforms than on rotary herringbone platforms which had no provision for head yoking of the cows. Although there were no significant differences in "cow-in" times or percentage of cows needing assistance onto the platform between circular and rectangular type holding yards, cow behaviour was slightly better in the group of rectangular yards studied. Mechanisation substantially reduced the amount of time spent on cleaning milking machines. It is clear that all milking systems have considerable potential for mechanisation. The amount and type of labour saved must establish the priorities put on mechanising the' various tasks involved in milking and cleaning. Mechanisation of the milking routine is pointless unless there is a corresponding increase in the number of milking units per operator. Techniques for data collection and presentation must be simplified and standardised to enable comparison of results between surveys and between milking systems, e.g. throughput should be expressed as cows per man hour per milking unit as well as cows per man hour, to permit meaningful comparisons. Good cowmanship is critical to the success of a milking system. "Cowmanship" needs to be clearly defined and. further investigated. Variations in milker and cow behaviour in the milking systems studied in the survey indicate that the principle of shifting the emphasis from one of forcing cows to conform, to one of encouraging them to ca-operate by conditioning and training, warrants further research
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ItemThe ability of sheep and goats to utilize crop by-products( 1977)Two digestibility trials and one feeding experiment were implemented. In the first digestibility trial sheep were fed rations of hay to which was added (w/w} 10%, 20% and 30% of rice bran, soybean meal and cassava respectively. The results showed that changes in digestibility were not directly proportional to the amount of the ingredient added, thus the individual analysis or digestibility of a single food does not necessarily indicate its feeding value in mixed diet. In the second trial the digestive efficiency of sheep and goats was compared when fed low, medium and high quality diets as represented by oat straw, meadow hay and sheep fattening pellets. For all practical purposes the sheep and goats were similar in their ability to digest all diets but there was some evidence to show that the goats made better use of crude protein in the oat straw and crude fibre in the pelleted diet. In the feeding experiment the same by-products that were used in the first digestibility trial were variously combined to investigate the best mixture for fattening sheep. The best liveweight gains were obtained from diets D2 and D3. D2 contained 33% hay, 30% rice bran, 25% cassava and 12% soybean meal.' D3 comprised 40% hay, 15% rice bran, 30% cassava and 15% soybean meal.
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ItemThe ecology and physiology of two species of Carduus as weeds of pastures in Victoria( 1977)Slender thistles (Carduus pycnocephalus and C. tenuiflorus) were introduced to Australia about the 1880s. They are now important weeds of pastures in much of southern Australia and are difficult to control with present methods. This study was undertaken to investigate several aspects of the ecology and physiology of the plants with the belief that a knowledge of some of these aspects, particularly of seed germination and seedling establishment, might disclose some "weakness" in the plants' growth which could be exploited to improve control measures. Because of confusion over differences between the two species which occur in Australia the initial step was to evaluate the morphological features which have been used to distinguish between the two species. Although they are very similar morphologically, cytological evidence confirmed that the two species were quite distinct and, in fact, had quite different evolutionary origins. Germination of seeds of slender thistles is controlled by three separate forms of dormancy; these are known as innate, induced and enforced dormancy. Dormancy ensures that the plants will survive in a Mediterranean-type climate and also colonize areas with quite different climates and, most importantly, survive natural catastrophes such as drought, fire, and flood. The germination of slender thistles in the field is confined to a very short period (about 6 weeks) after the autumn break in any year. This is a "weakness" in the plants' survival mechanism because they are vulnerable in that year, at least, to any treatment which can kill seedlings. The herbicide, diquat, was found to kill young seedlings of slender thistles and not affect seedlings of desirable pasture plants associated with the thistles in southern Australia. This treatment is economical and leads not only to a reduction in thistles but an increase of about 30% in pasture production. Several other aspects of the plants' growth were investigated. Slender thistles have early growth characters which give them advantages over more desirable components of pastures. They are more competitive than subterranean clover and ryegrass over a wide range of levels of nutrients, and the traditional approach to pasture improvement in southern Australia of applying superphosphate and sowing subterranean clover will encourage, not suppress, slender thistles. Since grazing animals generally do not eat slender thistles the presence of thistles in pastures at densities commonly occurring in Victoria considerably reduces pasture production.
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ItemEffects of growth patterns on body composition and compensatory growth in sheep( 1977)The literature related to compensatory growth in ruminants, with particular reference to sheep, has been reviewed. An experiment was conducted which examined the effects of planned BW losses on growth rate, body composition, wool growth and nitrogen and energy utilisation of sheep when ad libitum feeding was resumed. Sheep were fed a pelleted ration throughout the experiment, and BW loss induced by reducing feed intake. Following developmental growth from 30 to 37.8 kg, Groups B and C lost 21% BW at 122 and 63 gd-1, respectively to reach 30.2 kg BW. Following developmental growth from 30 to 46.7 kg (Groups D and E), Group D lost 34% BW at 125 gd-1 to reach 30.8.kg BW, while Group E lost 23% BW at 157 gd-1 to reach 35.0 kg. Group A was a control group fed ad libitum throughout the experiment. When ad libitum feeding was resumed compensatory growth occurred in treatment groups for up to 10 kg recovery of BW. Group D showed the most persistent increases in growth rate compared with that of control sheep, however, above 50 kg BW there were no significant differences between groups in growth rate. Weight loss did not produce a reversal of the compositional changes which occurred with increasing BW during developmental growth, in the whole body, carcass or offal. However, differences in composition between groups at the end of weight loss were not significant. During compensatory growth there were few differences between groups in the relative growth rates of protein, fat, ash or water in the whole body, carcass or offal. There were some differences between groups in weights of components at specific BW, carcass weight (CW) and offal weight WW), most notably fat and ash. However, these differences appeared to be transitory, and reflected the composition of that portion of the animal at the start of realimentation, rather than an effect of weight loss which was maintained during compensatory growth. The body, carcass and offal composition of sheep appeared to be resilient to periods of nutritional stress, and tended to return to the "normal" composition expected at that weight. The effects of up to 18 weeks severe undernutrition, resulting in rapid BW loss, were able to be overcome during compensatory growth when feed was offered ad libitum. Compared with developmental growth, nitrogen retention increased during compensatory growth. However, the efficiency of ME utilization was not different during these two periods of growth, although DE requirements for maintenance were lower during compensatory growth, compared with developmental growth. Dry matter intakes (DMI) of treatment groups required up to 13 weeks to return to the DMI of sheep during developmental growth, once ad libitum feeding was resumed. Over their respective growth paths Groups A, B, C, D and E required the same amount of feed to reach 50 kg BW. Wool growth rate (WGR) responded more slowly than BW to changes in level of nutrition, both during weight loss and during compensatory growth. There was a lag phase of at least 30 days. WGR during compensatory growth was reduced and required up to 14 weeks to return to developmental WGR after ad libitum feeding was resumed. Total body water (TBW), estimated from tritiated water (TOH) space in sheep undergoing compensatory growth, was overestimated by at least 20%. TOH space was measured without imposing a period of prior starvation on the sheep, and this may have contributed to the large overestimate. Multiple regression equations including TOH space, BW and a maturity factor (M), were able to explain up to 95% of the variation in chemical composition of the body, but residual standard errors were still high.
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ItemThe behaviour of sheep in narrow lane-ways( 1977)This thesis presents a study into the behaviour of sheep with particular emphasis on sheep movement and behaviour in narrow lane-ways. It is divided into five sections. The first section consists of a review of the behavioural implications associated with domestication. This review topic gives the reader a brief synopsis of previous work and conjecture on the behavioural and physiological responses of sheep. Although this review is only indirectly related to the experimental work it does emphasise the importance and relevance of behavioural studies to the agricultural industry. The second section describes an experiment aimed at investigating some of the factors which affect movement of sheep through races and to provide information required for the design of future work. The movement of flocks of sheep through races (narrow lane-ways) was observed and the effect of (1) forced or voluntary movement (2) whether the sides were open, partially covered or totally covered and (3) flock size, were examined. Differences in the movement of individual sheep were also investigated. Flock size (10 or 20) had very little effect on the movement of sheep in races. When sheep were forced through the race they ran faster, were more bunched and held their heads higher than when moving voluntarily. The race type effect on sheep movement was greatest when sheep were moving voluntarily. This suggests that forcing sheep masked the race type effect. A relatively consistent order of sheep through the race suggests that sheep maintain similar positions when running through races. This effect was reduced when the sheep were forced. Sheep moved faster through open or partially covered races than through totally covered races. They were also more bunched and held their heads higher as the race was increasingly covered. The remaining sections discuss experiments concerned with the evaluation of the current folklore or principles of sheep handling and behaviour. The third section discusses the movement of sheep around corners. The movement of flocks of 20 sheep through races (narrow laneways) incorporating an angle was observed, and the effect of (1) width of race, (2) whether the sides were open or covered and (3) the angle of corner, were examined. Sheep ran faster through races 1.5 m. wide than through races 0.5 m. wide, because they could move as a group rather than being constrained to move in single file. In both narrow and wide races sheep ran faster and were more spread out when the sides were covered, than when the sides were open. Corners acted as an impediment to sheep flow because the spacing between sheep decreased before the corner and increased after it. In wide races the time taken to run through the race increased as the angle of the corner increased. However, in narrow races the corner appeared to have an overall acclerating effect, despite the increased spacing between sheep. The findings in section three have been accepted for publication by the Journal of Applied Animal Ethology. The fourth section discusses the movement of sheep up or down inclines. The movement of flocks of 15 sheep through narrow ramps and of 14 sheep through wide ramps was observed and the effect of (1) movement up or down the ramp (2) whether the floor type was slats, a solid surface or steps and (3) the angle of incline, were examined. In both narrow and wide ramps sheep ran faster and were more bunched when moving up the ramp, than when moving down the ramp. Steep slopes acted as an impediment to sheep flow, slowing the rate of movement of the flock and increasing the spacing between sheep at the end of the ramp. Floor type had no effect on sheep movement in the narrow ramp. In the wide ramp, the solid floor increased the sheep's rate of movement going up the ramp, but decreased it when sheep were descending the ramp. The fifth section discusses the movement of sheep through or into differing light intensities. The movement of flocks of 14 sheep through narrow and wide races (narrow laneways) was observed. A partition across the race allowed the light intensity to be varied independently on each side and the effects of four levels of light intensity i.e. 1.4, 88, 350, and 1,400 lux (dark, low, medium and bright respectively) were examined. The effect of different light intensity on the movement of sheep was not great. There was little evidence to suggest that contrast was important. The results suggest that sheep move more readily through or into brightly lit areas, but that this response is clearly dependent upon the first sheep's behaviour. From the results of these trials, revised "principles" of sheep behaviour have been obtained which have important implications for the design of yards, sheds and races.
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ItemA study of grazing sheep and cattle separately and together on annual pasture( 1977)The work reported in this thesis was conducted at Rutherglen Research Station, Victoria, between December, 1963 and December, 1974. Mr. J. G. Bath, Manager of Rutherglen Research Station until 1967, initiated plans for the study, and along with Mr. R. Jardine,Biometrician, Victorian Department of Agriculture, decided on the general design of the first experiment. I developed the project from that point. Mr. Jardine also commented on later design proposals and conducted any statistical analyses required. Las actively engaged in most of the field work, and through my assistant, Mr. J. J. L. Maden, directed the remainder. Dr. J. H. Arundel, University of Melbourne, advised on the procedures for measuring worm burdens in lambs, and his assistant, Miss Rosemary Black, conducted the worm measurements on samples I helped to prepare. Dr. R. H. Watson, at the time Chief, Division of Animal Industry, Department of Agriculture, assisted with the writing of the first paper, and Dr. J. H. Arundel completed the fourth paper after I had prepared the first draft. Mr. J. J. L. Maden, a co-author in two papers, assisted with the field work and, following my instructions, prepared the results for statistical analysis. Mr. I. D. Ada, a co-author in two papers, conducted some of the measurements reported. The units of measurement used in individual chapters were the official ones at the time that particular material was being prepared for publication, namely imperial units. in the first chapter and metric units in the following ones.
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ItemComposition of commercial pig diets and utilization of piggery wastes( 1977)The work presented in this thesis was part of an integrated study conducted by the School. of Agriculture and Forestry into various aspects of piggery waste utilization. Particular attention was given to the occurrence and source of mineral elements in pig diets and piggery wastes. Results of analysis of commercial pig diets and piggery wastes are discussed in relation to nutritional requirements and toxicities and from environmental and legislative aspects. The Literature Review in Chapter 2 describes how similarities in the atomic orbital configurations of some transition elements and oxy-anions can explain the synergisms and antagonisms displayed by these chemical entities in biological systems. In particular, the concept of orbital equivalence is used to explain some of the better known cases of mineral antagonisms affecting the health and nutrition of livestock. The antagonism between sulphate and molybdate ions is discussed relative to their ionic structures and to their respective involvements in copper metabolism. The interactions of copper, zinc and iron are examined, particularly in relation to pig nutrition. Interactions between copper, zinc and cadmium are related to their orbital structures and to their ability to form metallothioneins. The ability of high levels of copper and zinc to induce selenium deficiency in chicks is discussed and associated with the similar orbital configurations of zinc, copper and selenate ions. Caution is proposed in the formulation and mineral supplementation of multi-constituent diets used in intensive animal production. Procedures used in the development and calibration of analytical techniques for the determination of eleven elements in pig faeces and pig diets are described in Chapter 3. Copper, zinc, iron, cadmium, lead; sodium, potassium, magnesium, calcium and phosphorus were measured from a single sample digestion using a nitric-perchloric acid mixture. Phosphorus content in the digest was determined colorimetrically and the remaining elements by atomic absorption spectrometry. A separate digestion procedure was required for arsenic which was then measured by atomic absorption spectrometry after generation of arsenic as its hydride. Accuracy and precision of the techniques were rigorously tested using standard addition and recovery procedures- and comparison of values obtained after analysis of the U.S. National bureau of Standards Reference Material ''Orchard Leaves". Chapter 4 reports the chemical composition of pig diets, ingredients of diets and mineral-vitamin supplements collected from 24 commercial piggeries in Victoria. An evaluation of the diets relative to the suggested dietary mineral requirements for grower pigs proposed by the Agricultural Research Council (A.R.C.) indicated that mineral imbalances occurred in many of the diets. High levels of cadmium and lead found in some diets originated principally as contaminants of mineral additives and from meat meals, meat and bone meals and fish meals. The mineral content of the diets was found to be highly variable and indicated differences in choice of dietary ingredients and in the practice of mineral supplementation. Copper, zinc, and iron levels in the diets were particularly variable and in the case of zinc and iron were present at concentrations far in excess of the levels suggested by.the A.R.C. Chapter 5 describes the chemical composition and in vitro organic matter digestibility (OMD) of pig faeces samples collected from 24 piggeries in Victoria. Pig faeces are shown to be highly variable in chemical and nutrient content and, in some instances, to contain high levels of potentially toxic mineral elements such as copper, cadmium, lead and arsenic. Wide ranges in in vitro OMD values, proximate constituent concentrations and cell wall composition were also recorded. Multiple regression analysis associated low in vitro OMD with high values of cell wall content, phosphorus, copper and lignin/cell wall. Standard additions of phosphorus and copper to pig faeces samples undergoing in vitro fermentation significantly lowered the OMD values of these samples, contributing further evidence of the possible inhibitory effects of these elements to the digestive processes of the ruminant. Some health aspects of refeeding pig faeces as an ingredient in diets for ruminants are discussed, particularly in relation to the presence of toxic minerals such as copper, cadmium and lead. In Chapter 6 a procedure is described for calculating the chemical composition of pig manure using dietary composition, recommended feed intakes, published retention values for each element and estimated excreta outputs fin. an "average" pig of 45 kg liveweight. The variability in the calculated composition of manure is discussed in relation to existing and proposed guidelines limiting the rates of application of pig manure to land. Some aspects of the proposed guidelines for Victoria are discussed; particularly in relation to the suggested maximum rates of manure application to provide not more than 500 kg of nitrogen or 300 kg of potassium/hectare/ annum. Because of the range in the estimated nitrogen content of pig manures, the quantities of manure supplying 500 kg of nitrogen were calculated to range from 46 - 123 tonnes with an average of 63 tonnes. Included in these quantities were widely varying amounts of other elements which would be applied to land with 500 kg of nitrogen; some of which are known to pose environmental problems through leaching to ground water, as run-off to waterways or through ingestion by grazing animals. The potential environmental hazards of applying large amounts of minerals, including heavy metals, to land are discussed and a method is proposed which would permit a more accurate estimate of manure loading rates to provide 500 kg nitrogen/ hectare of land.
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ItemFarm size, structural change, and adjustment policy : a study of the dried vine fruit industry in Sunraysia and Robinvale( 1977)Dried vine fruit farms in Sunraysia and Robinvale were nearly all established under closer settlement schemes, with farm size averaging about 8 hectares. The present study indicates that economics of size exist up to a harvested area of about 25 hectares. This would suggest that structural change is occurring in the industry, with farms being amalgamated to take advantage of these economies of size. However, structural change in recent years has been negligible. Some of the obstacles to adjustment are examined in the thesis. They have important implications for government policy; in particular, there is a need for a Land Authority to facilitate adjustment in dried vine fruit growing regions. The thesis also considers some methodological problems in estimating economies of size, and in deriving policy proposals from such estimates. It concludes that the results of most studies of farm size, including this one, must he regarded as provisional, pending the outcome of properly designed empirical tests. It also concludes that the Paretian concept of efficiency is inadequate as a framework for adjustment policy. I would like to thank my supervisors,Mr. G.W. Edwards, Mr. N.H. Sturgess, and Dr. A.S. Watson, for their advice and encouragement during this study. I am also grateful to Mr. John Connell who colaborated on a preliminary statistical analysis (see Section 4.1.6). Acknowledgement is made to the Bureau of Agricultural Economics for the data used in the empirical sections of the thesis. I am grateful to Mrs. Sue Valiance for her excellent typing of the manuscript, and to Mr. Bill Dahl for preparing the diagrams. I was assisted financially by an A.M. White Scholarship and an R.W.S. Nicholas Scholarship. Finally, I would like to thank my wife, Jacky, for her financial support, for help in preparing the bibliography, and for her patient encouragement.