No description available.

No description available.

A series of experiments was carried out to study the factors affecting faecal endogenous P excretion in sheep. Experiments 3.1, 3.2 and 3.3 involved intensive balance measurements and radio-isotope (<SUP>32</SUP>P) dilution measurements made on 6 mature sheep, to study the effect of changing salivary secretion on P metabolism. A hay diet (P intake 2.2 g/d) was fed in 3 different physical forms (finely ground, coarsely ground and chopped) in experiment 3.1 and a low-P oat husk based diet was given in coarse or finely ground form in experiment 3.2. The results of both the experiments indicated that there was no change in salivary P flow, faecal endogenous P excretion and P balance within each experiment. In experiment 3.3 sheep were fed different amounts of a low-P (P intake 1.2 g/d) oat husk based diet (0.8, 1.1 and 1.4 kg/d). There were no significant changes in salivary P flow or balance position. However, in this experiment there was an increase in faecal endogenous P excretion but the size of this increase with increase in dry matter intake was less than that reported by TCORN (1989). This increase was attributed to increased secretion of P in the intestinal secretions in response to an increase in dry matter flow through the intestine. Experiments described in Chapter 4 were performed to explore the possibility of using sheep maintained by total intra-gastric infusion to measure minimum endogenous excretion of P in faeces and urine. The results indicated that sheep given a near zero P intake excrete amounts of P that are comparable with the levels predicted by ARC (1980) as minimum endogenous P excretion. Chapter 5 describes experiments carried out to investigate factors affecting intestinal P absorption in the sheep. Experiment 5.1 was aimed at studying the effect of increasing demand for P, by intravenous infusion of CaCl<SUB>2</SUB>, on intestinal P absorption. The results of this experiment showed that while the amount of dietary P absorbed is mainly determined by P intake there is a component of this system that is sensitive to changes in P requirement. There was an increase in intestinal P absorption but no change in endogenous P secretion into the gut. Three sheep surgically prepared to isolate a one-metre section of proximal small intestine were used in experiments 5.2 and 5.3. In the Experiment 5.2 sheep were given a continuous intra-venous infusion of a buffered solution of P (Na<SUB>2</SUB>HPO<SUB>4</SUB>NaH<SUB>2</SUB>PO<SUB>4</SUB>, 3g of P/d) and the loops were perfused with a solution (pH 4.5, Tonicity 280 mOsmol/litre) containing 30 mmol/litre of P. The results showed that the amount absorbed was much less during intravenous P loading. Experiment 5.3 was performed to study the absorption of P from the intestinal loops when they were perfused with solutions containing a fixed quantity of P at varying P concentrations (20 mmol/litre and 30 mmol/litre). There were no significant differences seen either in the total amount or in the absorptive efficiency between treatments. A lactation study (described in Chapter 6) was carried out to investigate the effect of feeding a high protein diet on Ca and P metabolism. Measurements were made on two groups of six ewes with one group being restricted in protein supply while the other group was given supplementary protein in the form of blood meal. Balance measurements were made over 10-day periods separated by 10-day rest periods. <SUP>45</SUP>Ca and <SUP>32</SUP>P were used to measure faecal endogenous Ca and P losses. An extra balance experiment was carried out on the second set of ewes after they ceased producing milk. The results indicated that the loss of mineral from the skeleton in ewes in early lactation is proportional to milk production and is not directly dependent on dietary protein supply or N balance. The results also suggested that the rate of repair of bone matrix and its mineralization during the post lactation period is affected by protein supplementation. Two experiments (Experiments 7.1 and 7.2) were carried out to study the effects of high dietary Ca:P ratio on faecal endogenous faecal excretion in mature sheep which were given sufficient P to meet their maintenance requirement according to ARC (1980). The results obtained showed that faecal endogenous P excretion was not significantly affected by feeding diets high in Ca. All animals had a level of salivary P secretion that was more than adequate to meet rumen microbial requirements. Experiments 7.3 was a slaughter study carried out to investigate the effects of an increase in Ca intake on growth of the young lambs fed on diets supplying just sufficient P to meet their estimated requirements based on the revised TCORN (1989) growth model. A total of 40 lambs in four treatment groups were used in this study. The results of this trial showed that feeding high levels of Ca had no adverse effects on growth of the lambs when P was adequate . There was no beneficial effect of feeding excessive Ca and P but there was an increase in the incidence of urinary calculi. The amounts of Mg retained by the lambs were lower than the levels on which ARC (1980) based their estimates of requirements.

No description available.

No description available.

In this study, data collected in a survey of Scottish sheep farmers was used to corroborate and augment secondary data available in the literature on sheep ectoparasites and their control in 1999/2000.  The data was used to design and construct a decision tree model, which was used to determine probability weighted profit-maximising control strategies for six flock types/size groups that were representative of Scottish sheep farms.  Organophosphate (OP) based dips, applied in both the autumn and spring/summer, were found to be the profit-maximising control strategy for five flock types/size groups.  The exception was for small (100-ewe) lowground flocks, where two applications of cypermethrin in pour-on formulation maximised the avoidable disease losses. Each of these strategies can give rise to animal welfare, human health and /or environmental externalities.  OP dips can damage human health and the environment but minimise animal welfare losses, and cypermethrin pour-on, while non-damaging to human health and the environment, can result in some avoidable welfare losses, as ectoparasite control is less effective than for OP dips. Using multi-criteria analysis (MCA), the economics of sheep ectoparasite control from a social standpoint has also been examined.  Some profit-maximising control strategies do not necessary maximise social benefits.  A conflict can arise between the farmer and society.  The minimum cost that society would need to be willing to accept in order to finance possible incentives for sheep farmers to switch from the profit-maximising control strategy to strategies that provide different bundles of social benefits is estimated.

No description available.

Includes bibliographical references (leaves 267-292). / xx, 386 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study aimed at finding better ways of storing ram semen at refrigerator or room temperature with particular reference to ingredients readily available in Indonesia, namely coconut extract and quail egg yolk. Coconut extract showed consistent advantages with regard to sperm motility and quail egg yolk was as effective as hen egg yolk. Investigations were extended to examine storage for subnormal semen such as would be produced during periods of heat stress. Motility was assessed visually and using a Hamilton Thorn semen evaluation apparatus. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Sciences, 1997?

Bibliography: leaves 172-214. / 214 leaves, [41] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Interleukin-12 (IL-12) is a heterodimeric cytokine composed of two disulphide-linked subunits, p35 and p40, which form biologically active p70. IL-12 is able to induce IFN-y production from T and NK cells, and promote the proliferation of mitogen-activated T cells. It is thought that IL-12 may be an important cytokine in the initiation and progression of allograft destruction. This thesis describes the characterisation of ovine IL-12. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 2000

vii, 261 leaves : photos., ill., tables, graphs ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Zoology, 1979