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Limited published data exists on the Australian duck industry, particularly in relation to the nutritional requirements of the commercial duck (Anas Platyrhynchos). A series of seven experiments was designed to determine whether current nutritional recommendations for energy, lysine, methionine, threonine and tryptophan were sufficient to optimise growth, feed efficiency, and carcass characteristics of the duck. The ability of the duck to perform diet self selection was then examined for its potential use in the Australian industry. The outcome of the diet self selection experiments showed that ducks sometimes self select diets when offered choices from four diets differing in nutrient density. A key outcome of this research was the development of a revised set of nutrient specifications designed to maximise the performance of the Australian commercially grown duck. These proposed specifications could be economically beneficial to the expanding Australian duck industry / Doctor of Philosophy (PhD)

Corrigenda inserted behind title page. / Copies of author's previously published articles inserted at end. / Includes bibliographical references (leaves 193-210). / xxii, 210 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates whether estrogen modulates the proteins associated with calcium transport (eg calcium binding protein, calbindin D28k) in the intestinal tissue during sexual maturation of laying hens. Studies the temporal and spatial expression of estrogen receptors (ER) and calcium binding protein in jejunal tissue. Findings indicated the potential of estrogen to induce calbindin D28K in the intestinal tissue, from which it can be concluded that estrogen may increase calcium absorption and consequently calcium retention. Shows that the amount of estrogen normally present in the reproductive system is sufficient for the normal capacity of egg and eggshell production. Egg production and shell quality are significantly reduced by phytoestrogen. It is recommended that the concentration of phytoestrogen in poultry diets be investigated in more detail as it may act as an anti-nutritive factor and affect metabolism and productivity. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 1999

In a series of indoor and outdoor experiments with young sheep, feed supplements having different protein content were investigated. The supplements were chosen as those likely to elicit different Protein:Energy (P/E) ratios in the nutrients absorbed by the animal. The objective was to identify and characterize those that would support faster growth rate, bigger and leaner carcass production for the meat market, in different seasons in Southern Victoria, Australia (35-37° South, 141-143° East). Throughout, the GrazFeed model provided a reference system chosen for prediction of performance, with which the results of grazing experiments could be compete. / Supplementary feeding experiments were undertaken in the field (Experiments 1 and 4) in seasonal periods in which the pasture base found to poorly support high growth rates of weaned lambs. These experiments were supported by nutritional studies in pens (Experiments 2, 3 and 5) and supplement effects were evaluated in terms not only of liveweight but carcase and meat characteristics. Supplements used were evaluated and selected for use in further experiments on the basis that they would provide additional metabolisable energy but also would differ in the amount and nature of the crude protein they supplied and thus deliver different balances of absorbed nutrients, in particularly different P:E ratios. / Fish meal, with a high content of rumen undegradable protein of high biological value was used in each of these experiments to provide a test of the hypothesis that slow ruminal degradation and additional protein digested in the small intestine can influence animal response. In Experiment 1 and the related pen Experiment 2, comparing a lower to a higher P (CP%):E(MJ/kg) ratio feeds (barley, 12:13 P:E ratio) to (fishmeal / lucerne meal, 1/2 w/w, 35:10 P:E ratio), barley resulted in higher fat and lower protein amounts deposited as carcass components (P<0.01). The animals consuming extra protein were larger, leaner and became more uniform as a flock in terms of the range in LW and fat content at slaughter than those provided with supplements that are classed as energy feeds. / In Experiment 3 a range of alternative protein rich feeds and composite supplements was assembled that are cheaper and more readily available than fishmeal, with the idea that different patterns of ruminal degradation, intra-ruminal N availability and amounts of RUP could be created that would be beneficial in terms of the overall animal response. The paths of rumen protein degradability was determined with nylon bag techniques, and this was used to select feeds for investigation in a field and indoor experiments, Experiments 4 and 5. / In Experiment 4, grazing animals supplemented with lupines; (P:E 32:12), fishmeal / wheat bran 1/2 w/w (P:E 35:12) and formaldehyde treatment protected sunflower meal / wheat bran 1/2 w/w (P:E 24:11) responded poorly to the supplements where quality and quantity of pasture was such that unsupplemented growth rates were predicted to be poor by the decision support model, GrazFeed. In this and the supporting pen Experiment 5, the liveweight gain, final weight and dressing percentage of all supplemented lambs were significantly better than those of control (grazing only) animals (P<0.05). High and low commencing LW animals responded to protein supplements differently when these were fed at 1% BW with ad libitum medium quality roughage diet in indoor conditions. The heavier subgroup of fish meal / wheat bran (P:E 35:12) animals were significantly fatter than the heavy subgroup of wheat bran (P:E 17:10) animals (P<0.001). Lighter subgroup of animals were leaner and became more uniform (less variable) in weight and composition as a flock. Both the heavy and the light liveweight subgroups of fish meal grew faster but were fatter at slaughter than any other sub-groups. Lightest lambs fed bran grew from 26 to 36 kg in 10 weeks and had the most suitable carcase with the lowest priced supplement tested in the experiment. / Though protein supplementation had a positive effect on lamb performance; the advantage of high RUP was not consistent or always statistically significant. Compared to the alternative protein rich feeds, fish meal showed no cost effective advantage. The consequence of this current or possible future market conditions for feeding strategies for high quality lamb production are considered.

Transactions of magnesium (Mg) along the gastrointestinal tract and the effect of change in potassium (K) intake were recorded in two in vivo experiments in sheep and cattle. Additional information on the sensitivity to K intake was obtained by comparing Mg transport and electrochemical properties of isolated rumen epithelia of sheep and cattle in 4 additional in vitro experiments. The experiment described in Chapter 2, and performed in sheep housed indoors in metabolic crates, investigated the compensatory capacity of the intestine to respond to the reduction in Mg absorption from the stomach as a consequence of increase in K intake. The animals were equipped with a ruminal cannula and two intestinal cannulae (duodenum and ileum) and flow of digesta was measured by the addition of two indigestible markers, chromium ethylenediaminetetra-acetic acid (Cr-EDTA) and ytterbium acetate (Yb). The animals were infused in a Latin square design for periods of 10 days with a solution of K bicarbonate that provided between 15 and 47 g of K/day. The diet consisted of a 50:50 combination of concentrates plus lucerne hay that provided around 3.7 g of Mg per day and 15 g of K per day. After 5 days of infusion samples of feed, faeces, urine and plasma were collected and analysed for Mg and K content. After 6 days of infusion, samples of duodenal and ileal flow were obtained. The treatments reproduced the detrimental effect of K on Mg absorption, especially in the rumen; a rise in K intake from 15 to 23 g/day reduced total Mg absorption from the gastrointestinal tract from 1.36 to 1.23 g/day, further increase in K intake to 38 and 47 g/day reduced absorption to 1.12 and 1.05 g/day, an overall reduction of around 50% in Mg apparent availability. Magnesium was mainly absorbed in the stomachs and large intestine with the small intestine a site of net secretion. Most of the reduction in Mg absorption with increase in K intake occurred in the stomachs, reducing from 1.86 to 1.11 g/day. A compensatory reduction in the net secretion of Mg from the intestines (small and large) was observed. This compensation was largely due to reduction in net secretion from the small intestine, from 0.85 to 0.22 g/day, rather than an increase in net absorption from the large intestine, although both segments acted synergistically. Results also suggested significant individual variation in plasma Mg concentration, urinary Mg excretion and in the flow and absorption of Mg along the gastrointestinal tract. It was suggested that most of that variability was due to genetic factors. Differences between species (cattle and sheep) were pursued during the course of the experiment described in Chapter three. Four triple cannulated rams and 3 triple cannulated dry cows were placed in metabolic crates, fed daily fresh-cut pasture and infused, in a total randomised design that provided the equivalent of an intake of 30,40 and 50 g of K per kg dry matter intake (DMI) per day. Solutions of K (as K bicarbonate) and markers (CrEDT A and Yb acetate) were infused continuously for a period of 10 days; after 5 days of infusion samples of pasture, faeces, urine and plasma were collected and analysed for Mg and K content. After 6 days of infusion, samples of duodenal and ileal flow were obtained. Total feed offered, refusals and water consumption were recorded daily. Results showed a greater sensitivity of cattle to the increase in K supply. A rise in K supply from 30 to 40 g per kg DMI/day reduced Mg absorption by almost 50% from 0.32 to 0.16 g per kg DMI/day, whereas only the highest treatment dose (50 g of K per kg DMI/day) produced the same deleterious effect in sheep. The absorption of Mg occurred mainly in the stomachs and large intestine; in contrast the small intestine was a site of net secretion in both species. The addition of K slightly reduced the rate of Mg absorption from the rumen, especially in cattle. Similarly, net Mg secretion within the intestines increased with increasing K intake in both species, only to be counterbalanced by a greater Mg absorption from the large intestine. The large intestine in both species (sheep and cattle) reduced faecal losses of Mg but was unable to fully compensate for the reduction in Mg absorption from the stomach or the greater net Mg secretion observed at the small intestine. Differences between species in water content of the faeces were observed to be mainly related to the moisture content of the digesta that reached the ileum rather than a result of differences in absorption in the large intestine. More evidence of species differences in Mg transport and of sensitivity to K intake were obtained by using isolated rumen epithelia and the Ussing chamber technique. Transport and electrophysiological properties of the tissues were observed in standard conditions and by adding different K concentrations to the mucosal side. Under standard conditions and open-circuit voltage, sheep isolated rumen epithelia had greater transmural potential difference (PDt), and lower conductance (Gt) but similar short-circuit current (Isc) than those from cattle. These results suggested that the rumen epithelium of cattle is leakier than that of sheep. Measurement of the transport of Mg showed that isolated rumen epithelia of cattle transported more Mg and was saturated at higher Mg concentrations (12 vs 4 mM) than sheep epithelia. These differences in Mg influx (transport from mucosa to serosa) were also observed in studies of Mg transport using stable isotopes. Magnesium influx (transport from mucosa to serosa) from the isolated rumen of cattle was greater than in sheep (57.5 ± 12.72 vs. 17.3 ± 12.72 nmol.cm⁻².h⁻¹); however this was counterbalanced by a greater Mg efflux (transport from serosa to mucosa) of 48.1 ± 12.72 vs. 9.9 ± 12.72 nmol.cm⁻².h⁻¹, for cattle and sheep respectively, when mucosal K concentrations were around 25 mM. A increase in K concentration on the mucosal side enhanced transmural potential difference (PDt) and short-circuit current (Isc) to a greater extent in sheep than in cattle, suggesting a greater effect of K on sheep than on cattle epithelia. On the other hand, the transport of Mg measured by stable isotopes suggested that net absorption of Mg (7.4 ± 12.72 vs. 11.1 ± 12.72 nmol.cm⁻².h⁻¹) in sheep epithelia was similar at 25 and 50 mM of K on the mucosal side, whereas net Mg influx in cattle was largely depressed as a consequence of a reduction in Mg influx (mucosa to serosa) from 57.7 ± 12.72 to 2.9 ± 12.72 nmol.cm⁻² h⁻¹ together with a constant Mg efflux (serosa to mucosa) 48.1 ± 12.72 and 41.2 ± 12.72 nmol.cm⁻².h⁻¹, presumably leaving through a paracellular shunt. However, this finding was based on date from a small size and caution should be applied to this conclusion. In conclusion, data collected from several comparative studies suggest differences in Mg apparent availability between sheep and cattle and also a greater sensitivity of cattle to an increase in K intake. This high sensitivity to K represents a great risk of hypomagnesaemia in dairy cattle in New Zealand where high K concentration is endemic in pastures. Most importantly, these results suggest that models for Mg metabolism in cattle should be based on measurements from cattle nutritional and physiological studies rather than on extrapolation from sheep studies.

Bibliography: leaves 151-166. This thesis describes the development of two novel and complementary analytical approaches for assaying cyanoalanine non-protein amino acids. These assays are used to determine the distribution of these compounds both within and between plants and to identify accessions of common vetch which contain low levels of the cyanoalanine non-protein amino acids in germplasm collections. These analytical tools are used to correlate toxicity observed in animal feeding experiments with the cyanoalanine content. This thesis covers also the first report of the use of diffuse reflectance using dispersive infrared spectrometry for the "in situ" quantification of specific organic components from plant tissue as well as the first use of micellar electrokinetic chromatography for the quantitative analysis of 9-fluorenylmethyl chloroformate (FMOC) derivatised and non-derivatised components of extracts from plant material.

Bibliography: leaves 107-130. This study evaluates quality of fermentation of the silage and also its nutritive value to ruminants on the basis of "in vitro" and "in sacco" digestability. Animal response to the silage is also evaluated in an "in vivo" digestability and nitrogen balance trial with Australian Merino sheep. The objective of this thesis is to investigate the opportunities for utilising citrus pulp and poultry litter to improve the nutritive value of wheat straw.

Graduation date: 2004

Two experiments were conducted to determine the effects of daily (D) vs alternate day (AD) supplementation of soybean meal (SBM) or wheat middlings (WM) on forage organic matter intake (OMI), ruminal digesta kinetics, total tract digestibility, and ADG of steers consuming low quality forage. In Exp. 1, five Angus x Hereford steers (403 �� 32 kg) fitted with rumen cannulas were utilized in a 5 x 5 Latin square design. Steers were individually fed low-quality (5.3% CP) fescue hay ad libitum and were randomly assigned to one of five treatments: no supplement (CON); WM fed daily (WMD); WM fed every other day (WMAD); SBM fed daily (SBMD); and SBM fed every other day (SBMAD). Supplements were formulated to meet 100% of degradable intake protein (DIP) and metabolizable protein (MP) requirements. Supplementation increased (P<0.05) hay and total OMI (g���kg��������BW�����) and total OM digestibility (%) compared to CON. Daily supplementation increased (P<0.05) hay and total OMI and hay and total OM digestibility when compared with AD supplementation. Hay OMI and hay OM digestibility was greater (P<0.01) for SBM compared to WM, but total OMI and total OM digestibility was not different (P>0.38). In Exp. 2, 96 Angus crossbred steers (280 �� 32 kg) were blocked by weight (three groups) into 12 pens in a randomized complete block design. Steers were fed low-quality (6.2% CP) fescue straw ad libitum, and one of four supplements formulated to meet 100% of the DIP requirements: WM fed daily (WMD); WM fed 3d/week (WMAD); SBM fed daily (SBMD); and SBM fed 3d/week (SBMAD). Straw OMI was greater (P<0.03) for D compared with AD supplemented treatments and for SBM compared with WM supplemented treatments. Total OMI was greater (P<0.01) for D compared with AD supplemented treatments, however, SBM had similar total OMI when compared with WM supplemented treatments. Daily supplemented steers had greater (P=0.03) ADG when compared with AD supplemented steers. Despite having lower forage intake and similar total OMI, steers consuming WM had higher (P<0.01) ADG when compared to steers consuming SBM. / Graduation date: 2003

We have previously shown that diets enriched with (n-3) fatty acids reduced the delayed-type hypersensitivity (DTH) skin reaction to keyhole limpet haemocyanin (KLH) in geriatric-Beagles. Although the amount of ��-tocopheryl acetate in diets of the previous study exceeded requirements, plasma ��-tocopherol concentration was significantly lower in dogs fed the high (n-3) fatty acid diets. There are several reasons that could explain the decreased DTH response. Some of these include decreased cytokine production, specifically, interleukin (IL) IL-1��, tumor necrosis factor (TNF) and IL-6 by mononuclear cells. Furthermore, the reduced DTH response could be attributed to increased levels of lipid peroxides or changes in plasma ��-tocopherol levels. In this study we examined the effects of feeding 32 healthy, female, geriatric-Beagles diets containing (n-6) to (n-3) fatty acid ratios of 37:1 and 1.7:1, while varying the content of ��-tocopheryl acetate, [high (447 ug/g), med (101 ug/g) and low (17 ug/g)] for 82 days on the DTH reaction. Consumption of the 1.7:1 fatty acid diets significantly increased the total content of (n-3) fatty acids in plasma compared to the 37:1 fatty acid diets (17.00 and 2.02 wt %, respectively). There was a significant interaction between the (n-6) and (n-3) fatty acid ratio and the concentration of ��-tocopheryl acetate in the diet on the plasma concentration of ��-tocoopherol. The concentration of ��-tocopheryl acetate in plasma of dogs fed the 1.7:1 fatty acid diets was 17.3, 25.4, and 35.4 ug/ml, respectively, for the low, med and high ��-tocopheryl acetate containing diets, and in dogs fed the 37:1 fatty acids diets was 20.8, 34.9, 52.4 ug/ml, respectively. Consumption of the 1.7:1 fatty acid diets with either low or high ��-tocopheryl acetate showed no differences in DTH response from each other or from dogs consuming the 37.1:1 fatty acid diets. When the dietary ��-tocopheryl acetate concentration was moderate, a significant suppression of the DTH response occurred at 48, 72, and 96 hr in dogs consuming the 1.7:1 fatty acid diet. These data suggest that an interaction exits between dietary (n-3) fatty acid content and ��-tocopheryl acetate on the immune response as measured by the DTH test. / Graduation date: 2000