Published theses
Doctor of Philosophy (PhD)
3. Larsen, John WA (1997) - The pathogenesis and control of diarrhoea and breech soiling ('winter scours') in adult Merino sheep.
2. Spath, Ernesto JA (1984) - Calving date and hypomagnesaemic tetany in beef cattle.
1. Donnelly, John R (1983) - The productivity of breeding ewes grazing on lucerne or grass-clover pastures.
Master of Veterinary Science (MVSc)
8. Kirk, Beata (2016)–Internal Parasitism and Production in Prime Lamb Flocks.
7. Tyrell, Leah (2013)–Comparison of Programs for the Control of Blowfly-Strike in Merino sheep in South-Eastern Australia.
6. De Cat, Sandra (2007)–The over-wintering ecology of Lucila cuprina in south-eastern Australia.
4. Swaney, Susan (2004) - Internal parasite infections of Merino sheep grazed at two stocking rates.
3. Niven, Paul G (2000) - The integration of grazing management with anthelmintic treatment to control trichostrongylid infections of sheep.
2. Ridge, Sally E. (1994) - Evaluation of an absorbed enzyme-linked immunosorbent assay for bovine Johnes disease and application of the assay to Johnes disease control in Victoria.
1. Grant, Ian M (1984) - Evaluation of a flock health and production programme in commercial flocks in south-west Victoria.
Graduates of Master of Veterinary Studies
26. Counsell, David C (2000) - Wool price risk management.
25. Cox, Jonathan W (1995) - Breeding bulls in a commercial beef cattle herd.
24. Thompson, Graham K (1993) - Prickly acacia infestation of the Mitchell grasslands.
23. Power, Megan E (1993) - Pasture renovation in north east Victoria.
22. Williams, Scott H (1993) - The effect of farm management practices on wool quality and income from wool.
21. Salmon, Elizabeth M (1992) - Genetic and economic gains from the use of artificial insemination and multiple ovulation and embryo transfer.
20. Maclean, Murray F (1992) - Practical aspects of changing from autumn to spring lambing.
19. Webb Ware, John (1992) - Control of Gastrointestinal parasitism in sheep flocks in Eastern Australia.
18. Taylor, Richard P (1991) - Ram breeding for the commercial woolgrower.
17. Irving, Rosemary F (1991) - Factors which influence the selection of time for shearing on a property in Gippsland.
16. Trengove, Colin L (1991) - Opportunities to improve farm profitability through genetic improvement of Merino sheep.
15. Carr, Anthony (1989) - Time of lambing: importance, extension and Implementation.
14. Nicholas, Masten (1989) - Opportunities to improve the profitability of four properties in Southern New South Wales.
13. Roberts, Daniel (1988) - A review of Footrot in Australian sheep flocks and a study of the factors associated with a farm being affected by Footrot in four shires in Western Australia.
12. Jordan, David (1988) - An evaluation of control programs for gastro-intestinal nematodes of sheep in New South Wales
11. Rolls, Peter (1988) - Drought - nutrition and management.
10. Daniel, Geoffrey (1988) - The importance of soil erosion when deciding upon farm stocking rate.
9. Allworth, Bruce (1988) - Control and eradication of Footrot.
8. Sackett, David (1987) - Sheep flock health and production management programs.
7. Watts, Tim (1987) - A review of permanent oestrogenic infertility in sheep and its effect on the profitability of merino wool Enterprises.
6. McGregor, Peter (1987) - Improving cattle health and production management services on the North Coast of New South Wales.
5. Brightling, Anthony (1986) - A review of State sheep lice control strategies for Victoria.
4. Nilon, Paul (1986) - Nutritional ill-thrift in weaner sheep: causes and management options.
3. Neithe, Geoff (1986)- Opportunities for implementation of herd health and production programs in the Northern Territory.
2. Abbot, Kym (1986) - Management evaluation on grazing properties in South Australia with particular reference to financial analysis.
1. Cameron, Simon (1985) - The role of nutrition, shelter and genotype in the prevention of neonatal losses in sheep.
The effect of time of shearing on wool production and management of a self-replacing merino flock
Choice of shearing time is one of the major management decisions for a wool-producing Merino flock and affects many aspects of wool production and sheep health. Previous studies have investigated the effect of shearing on only a few of these factors at a time, so that there is little objective information at the flock level for making rational decisions on shearing time. This is particularly the case for flocks that lamb in spring, the preferred time in south-eastern Australia.
A trial was conducted in a self-replacing, fine wool Merino flock in western Victoria, from January 1999 to May 2004, comparing ewes shorn annually in December, March or May. Within each of these shearing times, progeny were shorn in one of two different patterns, aligning them with their adult shearing group by 15-27 months of age.
Time of shearing did not consistently improve the staple strength of wool. December-shorn ewes produced significantly lighter and finer fleeces (average 19.1 μm, 3.0 kg clean weight), whereas fleeces from March-shorn ewes were heavier and coarser (19.4 μm, 3.1 kg). Fleeces from ewes shorn in May were of similar weight to fleeces from March-shorn ewes (3.1 kg), but they were of significantly broader diameter (19.7 μm). In young sheep, beneficial changes in some wool characteristics for each shearing group were offset by undesirable changes in others.
Shearing ewes in March or May, and weaners in March, May or June, significantly increased the risk of post-shearing mortality about three- and four-fold, respectively, compared to unshorn sheep. Substantial, highly significant associations in young sheep between post-weaning mortality, bodyweight and growth rate were also quantified using various survival analysis techniques. For example, the lightest 20% of weaners at weaning contributed 31% of all deaths in the year following weaning, and increasing average growth rate over summer and autumn from 250 to 500 g/month reduced the risk of death by 74%. These results could be used to develop supplementary feeding systems that efficiently reduce weaner mortality, which is a significant animal welfare issue in many Australian Merino flocks.
Mortality effects were incorporated into estimates of the total value of wool produced by the different shearing times between birth and culling at 6¼ years of age. Using median historical (1991-2006) wool prices, shearing ewes in March and their progeny first in June, or October (weaner)-December (ewe) shearing produced the greatest total value of wool ($111/head). March (weaners)-March (ewes) shearing had a wool value of $107/head and December (weaners)-December (adults) shearing $103/head. May-shorn ewes produced the smallest value of wool, irrespective of whether their progeny were first shorn in May or July ($93-96/head).
No shearing time consistently improved all animal health measures. May-shorn ewes had significantly more fleece rot in late autumn than the other shearing groups (odds ratio 2.5) and were up to 0.4 condition score lighter during winter, although they had a lower cost of dag (average $0.64/head) and significantly less breech strike risk in spring, compared to December-shorn ewes (odds ratio 0.18). December-shorn ewes had the greatest cost of dag ($1.50/head). March-shorn ewes had an intermediate cost of dag ($1.03/head) but significantly less breech strike than May-shorn ewes (odds ratio 0.38).
Overall, December and March shearing were shown to be appropriate alternatives for a self-replacing Merino flock in south-eastern Australia, whereas May was an undesirable shearing time.
The economic response to seasonal rainfall and the value of seasonal rainfall forecasts on Australian farms
A review of the relevant literature showed that the skill of Australian seasonal rainfall forecasts had not been verified and that the value of the forecasts for Australian farmers had not been clearly elucidated.
A study was conducted in which the Australian Bureau of Meteorology's seasonal rainfall forecasts were verified for 262 townships throughout Australia, from its inception in June 1997 to May 2005. The forecasts had low skill. Brier Skill Scores and the Receiver Operating Characteristic values were uniformly close to the no skill value. Forecast variances were consistently small. The overall observed variance was 0.0048, 2.1% of the variance of a perfect system. The estimate of the gradient of the outcome against forecast was 0.42 and was imprecise. Definitive statements about forecast biases cannot be made.
The economic value of the forecasts for decision-makers was estimated using value score curves calculated for six forecast scenarios. All curves indicated that no economic benefit could have been reliably derived by users of the seasonal rainfall forecasts, with the exception of users with decisions triggered by a small shift in the forecast from climatology, in which case small economic gains may have occurred. Small value scores were associated with the observed forecast variance, not the observed bias. The expected change in value scores associated with any future increase in forecast variance was also examined. This showed that a moderate increase from the observed variance would bring limited benefits. Substantial value to a broad range of users will only occur with a large increase in forecast variance. To deliver this, new lead indicators with markedly better predictive characteristics may need to be developed for the seasonal rainfall forecasting system.
The review of relevant literature also showed that the economic response of Australian sheep or cattle farms to increasing seasonal rainfall had not been clarified. A second study was conducted in which computer simulations of three wool producing businesses in south-eastern Australia (Canberra, Wagga and Hamilton) were modelled to determine the three moments of economic response to varying seasonal rainfall.
As autumn and spring rainfall increased, the first moment, or mean response in annual gross margin, increased at a declining rate and then asymptoted to a maximum. Median rainfall achieved a large proportion of the maximal gross margin, more so in autumn than spring. The first moment response to winter and summer rainfall was limited at all sites with the exception of summer rainfall at Hamilton, where increasing rainfall increased the mean annual gross margin.
The variance of annual gross margin, or second economic moment, declined at all sites with increasing seasonal rainfall, as did the skewness of annual gross margin, or third economic moment. In all seasons, at all three sites, with the exception of winter at Hamilton, the probability of loss declined rapidly with increasing seasonal rainfall. At all sites a drought during spring produced the greatest probability of loss.
Median seasonal rainfall achieved much of the maximal annual gross margin and a lower than average probability of loss. The driest tercile or decile is suggested as a better reference point for seasonal forecasts or as a decision trigger point than the widely used median.