School of Agriculture, Food and Ecosystem Sciences - Theses

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The role of diffused carbohydrates in the infection of stone fruit by Sclerotinia fructicola (Wint.) rehm

Whan, James Henry. (University of Melbourne, 1970)
Sunraysia : a social survey of a dried fruits area

McIntyre, A. J. (Alan John) (University of Melbourne, 1948)
Observations on fomes pomaceus (pers.) big. & guill. infecting plum trees ; An investigation of sooty moulds with particular reference to their taxonomy and their growth in culture

Fisher, Eileen. (University of Melbourne, 1974)

I. The Taxonomy of "Sooty Mould "-Fungi. 1. Existing schemes of classification are discussed. 2. A classification is offered in which, the inaccuracies of other taxonomic schemas, are corrected. 3. "Sooty Moulds� are arranged, according to the macroscopic appearance of their growth, into four groups. 4. Diagnostic features are given for five families of ��sooty mould"-genera. 5. The families Capnodiaceae v. Hohn. and Chaetothyriaceae Th. are emended. A key to the identification of the genera Included in each of these families Is given. 6. Chaetothyrium Citri (Arn.) nov. comb. is recorded for the first time in Australia. 7. A new species, Phycopsis australiensis is described. II. An Instigation of the Cultural Behaviour of some "Sooty Mould" Fungi with reference to Climatic Conditions. 1. Eight species which, were isolated from epiphytic moulds, are included in this study. 2. A preliminary survey is made of the nutritional recuirementa of these species. 3. The methods used for recording measurements of colony-size and for calculating the rate of growth are described. 4. Measurement is made of the growth occurring at the following temperatures: 10�C., 15�C., 18�C., 20�C. and 25�C. The optimum growth temperatures determined for seven "sooty mould" endemics lie between 15�C and 20�C. 5. The methods which were adopted for growing these fungi under conditions of controlled atmospheric humidity are described. 6. The humidity growth-rate relations determined here are similar to those of fungi from quite unrelated habitats. 7. The geographic distribution of epiphytic "sooty moulds" is discussed in relation to the temperature and humidity requirements of the species examined here. The temperature-growth relations of the Capnodiaceae species do not confirm the assumption that high temperatures are favourable, rather It would appear that growth is active during the winter months. 8. It la suggested that the deciduous nature of the flora in cool temperate regions is responsible for the almost entire absence of the Capnodiaceae in these regions.
The chemical modification of Pinus radiata (D.Don.) with furfuryl alcohol

Skewes, Brett Andrew. (University of Melbourne, 2006)

Wood blocks impregnated with furfuryl alcohol required a standing time of 48 hours to ensure complete swelling of the wood. Total penetration of the blocks was required for maximum swelling and water resistance in treated blocks. The presence of water in the treatment solution caused rapid swelling of the wood block, whereas 100% furfuryl alcohol created a slow rate of swelling. The presence of water in the cell walls accelerated the rate of swelling of 100% furfuryl alcohol, but not to the extent as when the water was present in the treatment solution. Dimensional stability decreased as the water content in the treating solution increased, but compared to the controls (6 - 8%) there was significant improvement in dimensional stability (2.5 - 4%). The resin forming efficiency varied with the amount of water present, but never dropped below 85%. Treated wood samples compressed to a density of 1200 � 1400 kg/m3 were more stable when exposed to water, and had increased hardness and MOE compared to untreated compressed samples. The curing of furfuryl alcohol in beakers gave a clear indication of catalyst performance with variable catalyst concentration and curing temperature. An increase in catalyst concentration increased the resin forming efficiency which was dependant upon the catalyst strength and number of pKa values. Of the catalysts stable at room temperature, oxalic acid, maleic acid and zinc chloride were the best performed for wood impregnation, with respect to the parameters investigated. The higher the resin forming efficiency the lower the volumetric swelling. The initial moisture content of the wood had a direct effect upon the swelling of wood blocks. All samples with an initial moisture content of 12% performed better than the corresponding treatments used with oven-dried blocks. Further, higher catalyst concentrations and curing temperatures improved performance. Oxalic acid at a 4% concentration with furfuryl alcohol and a 2% concentration with furfuryl alcohol � formaldehyde formulations produced the best resin forming efficiency, permanent swelling and water property results. Conditioning time between pressure impregnation and curing was unnecessary with no improvement in properties with the cured wood block. Furfuryl alcohol with a 4% oxalic acid concentration produced the most desirable overall results with resin forming efficiency (111%), permanent swelling (8%), water uptake (8%) and dimensional stability (2.8%), when cured for 24 hours at 120�C. Analysis of leachate by GCMS suggested that a minimum curing time of 12 hours is required with furfuryl alcohol and 6 hours with a furfuryl alcohol � formaldehyde formulation to substantially reduce the amount of leachable material from a treated wood block, confirmed by dimensional stability trials.
The chemical modification of Pinus radiata (D.Don.) with furfuryl alcohol

Skewes, Brett Andrew. (University of Melbourne, 2006)

Wood blocks impregnated with furfuryl alcohol required a standing time of 48 hours to ensure complete swelling of the wood. Total penetration of the blocks was required for maximum swelling and water resistance in treated blocks. The presence of water in the treatment solution caused rapid swelling of the wood block, whereas 100% furfuryl alcohol created a slow rate of swelling. The presence of water in the cell walls accelerated the rate of swelling of 100% furfuryl alcohol, but not to the extent as when the water was present in the treatment solution. Dimensional stability decreased as the water content in the treating solution increased, but compared to the controls (6 - 8%) there was significant improvement in dimensional stability (2.5 - 4%). The resin forming efficiency varied with the amount of water present, but never dropped below 85%. Treated wood samples compressed to a density of 1200 � 1400 kg/m3 were more stable when exposed to water, and had increased hardness and MOE compared to untreated compressed samples. The curing of furfuryl alcohol in beakers gave a clear indication of catalyst performance with variable catalyst concentration and curing temperature. An increase in catalyst concentration increased the resin forming efficiency which was dependant upon the catalyst strength and number of pKa values. Of the catalysts stable at room temperature, oxalic acid, maleic acid and zinc chloride were the best performed for wood impregnation, with respect to the parameters investigated. The higher the resin forming efficiency the lower the volumetric swelling. The initial moisture content of the wood had a direct effect upon the swelling of wood blocks. All samples with an initial moisture content of 12% performed better than the corresponding treatments used with oven-dried blocks. Further, higher catalyst concentrations and curing temperatures improved performance. Oxalic acid at a 4% concentration with furfuryl alcohol and a 2% concentration with furfuryl alcohol � formaldehyde formulations produced the best resin forming efficiency, permanent swelling and water property results. Conditioning time between pressure impregnation and curing was unnecessary with no improvement in properties with the cured wood block. Furfuryl alcohol with a 4% oxalic acid concentration produced the most desirable overall results with resin forming efficiency (111%), permanent swelling (8%), water uptake (8%) and dimensional stability (2.8%), when cured for 24 hours at 120�C. Analysis of leachate by GCMS suggested that a minimum curing time of 12 hours is required with furfuryl alcohol and 6 hours with a furfuryl alcohol � formaldehyde formulation to substantially reduce the amount of leachable material from a treated wood block, confirmed by dimensional stability trials.
Using portable sawmills to produce high value timber from farm trees in the semi-arid zone

Blackwell, Philip A. (University of Melbourne, 2002)

There is a perception by some within the sawmilling industry that portable sawmills cannot produce the sawing quality in hard high-density timbers that is required to be merchantable in the manufacturing industry � especially the higher value sectors such as furniture. This study investigated the on-site processing of farm timbers from the semi arid regions of Australia using two different portable sawmills. There were a limited number of plantations with sufficient quantity of suitable saw logs within the low rainfall regions of south-eastern Australia for sawing trials. The only plantations that had sufficient saw logs were of high-density eucalypt species. The four species selected were Brown Mallet (Eucalyptus astringens), Sugar Gum (Eucalyptus cladocalyx), Yellow Gum (Eucalyptus leucoxylon) and Swamp Yate (Eucalyptus occidentalis). The portable sawmills selected for investigation were at the lower end of automation available on portable sawmills. Both mills required an operator to push and pull the power head along the log to produce sawn boards. The mills used in the sawing trials were a single circular blade type sawmill, which was represented by a `LucasMiIl� Model 8' and a horizontal bandsaw type sawmill, which was represented by a `Laidlaw� Farmill'. Initial results showed the selected species produced dimensionally consistent 150 mm wide boards that could be used in the manufacture of furniture or other products. The key criterion for investigation of sawing with both types of portable mill was the straightness of cut as the measure of sawing accuracy. This was measured with a modified straightedge and digital calipers. A total deviation or waviness in the cut of less than 1.5 mm was considered acceptable. An investigation using the single circular blade sawmill sawing with four different width blade tips revealed the 5 and 5.7 mm wide Carbide-tipped blades produced straighter cuts than the 4.5 and 5.4 mm wide Carbide-tipped blades in each of the trial species. The 5.0 mm blade also produced straight cuts with the fastest feed-speed in the majority of species while the 5.7 mm blade was the slowest sawing blade. The use of a 5.0 mm tip width blade on a single circular blade sawmill could be considered as the most versatile blade that is capable of producing more straight cuts and at the fastest feed-speed when sawing high-density hardwood species than other tip width blades. Investigation using the horizontal bandsaw sawmill and varying the blade parameters of hook angle, tooth set and blade tension showed the consistency in obtaining the blade tension was a major factor in accurate sawing. At low blade tension, the straightness of cut was adversely effected. The other variables revealed that at the widest tooth set the deviation along the cut increased with the faster feed-speed. The range of hook angles tested had no effect on cut straightness. It is possible that at higher hook angles problems might occur, as experience within the sawmilling sector suggests, but the range selected in this study, inadvertently, did not extend that far. Investigation of three blade types with different tip construction and at different widths revealed the 32 mm wide Bi-Metal blade was the best general blade over the range of species. Although this blade did not produce the straightest cuts in all the species the cuts were within the accepted tolerance of 1.5 mm. The carbon steel and Carbide-tipped blade did produce the straightest cuts in some species but were outside the acceptable range in other species. A final trial to assess controlled feed-speed required the horizontal bandsaw to be modified with the attachment of a variable power feed unit to the sawing carriage. This modification allowed the feed-speeds to be doubled in most species without any reduction in the straightness of cut. The production of quality timber is technically feasible using portable sawmills if the conditions and parameters of the blade, timber and mill are matched to meet the problems each log will demonstrate during the milling process.
Studies on resynchronisation of oestrus with progesterone and oestradiol benzoate in Holstein cows

Eagles, Vicki Maree. (University of Melbourne, 2000)

Resynchronisation of return-to-service in cows using progesterone and oestradiol benzoate is an integral part of current recommendations for Controlled Breeding Programs and the treatment of postpartum anovulatory anoestrus to improve herd reproductive performance. This thesis describes the results of a series of three experiments designed to test some of the hypotheses on the principles of resynchronisation based on each of the following questions: a) What concentrations of plasma progesterone are sustained by re-using a CIDR device for resynchronisation as compared to concentrations sustained by a new device? b) What proportion of the cows that are not confirmed pregnant to first insemination can be successfully resynchronised; and, do any pregnant cows show overt symptoms of oestrus as a consequence of the resynchronisation treatment? c) Does the type of the resynchronisation treatment for cows originally diagnosed with anovulatory anoestrus affect the efficacy of treating this common condition in Holstein cows? Experiment 1: To identify changes in plasma progesterone concentration, a sequence of treatments with a new or recycled CIDR device in ovariectomised cows was used to model the respective plasma progesterone profiles in treated cycling or anoestrous cows. A total of 9 ovariectomised non-lactating Holstein cows were each treated sequentially with a new CIDR device inserted for 6 days (Round 1); then a new CIDR device was inserted 4 days after the first device was withdrawn, with an insertion period of 6 days (Round 2); and finally, the same device initially used in Round 1 was re-inserted for a period of 7 days (Round 3). A 1mg oestradiol benzoate injection was administered 24 hours after device removal at the conclusion of each Round. Every cow was observed for signs of behavioural oestrus during the subsequent 72 h period. Blood samples were taken at specified intervals during the period of device insertion (3 hours, Day 1 and Day 6 post-insertion), as well as immediately preceding device insertion and following removal 6 or 7 days later. The average plasma progesterone concentrations over the 6-day insertion period for each Round 1, 2 and 3 were: 3.2, 2.2 and 1.7 ng/mL, respectively. Concentrations were significantly higher in Round 1 (P<0.01), but were similar in Rounds 2 and 3. The highest progesterone concentrations in Round 1 were those measured 3 and 24 hours after device insertion. This reflected the delay in the induction of hepatic enzymes that metabolise progesterone and are not normally required by ovariectomised cows. The progesterone content of a CIDR device declined by 23% (1.83g 1.41g) over the first 6 days of insertion and by a further 20% (1.41g -� 0.98g) over the second 7 days of insertion. Every cow displayed obvious overt symptoms of behavioural oestrus within 48 hours of being injected with oestradiol benzoate in each Round. In conclusion, ovariectomised cows were a suitable model to characterise subtle changes in the concentration of plasma progesterone which occurred in response to administration of a new or recycled CIDR device per vaginum for 6 or 7 days. The profile of changes in plasma progesterone as a consequence of device insertion and removal was rapid and was influenced by previous exposure to progesterone. Similar plasma progesterone profiles were associated with the use of a new CIDR device or a recycled device when animals had been previously exposed to elevated levels of progesterone. Experiment 2: The characterisation of the profile of changes in plasma progesterone concentration in response to a resynchronisation treatment initiated during middioestrus and subsequent to a synchronised first oestrus, in lactating Holstein cows involved in a commercial Controlled Breeding Program. It was also to determine if a recycled device could elevate plasma progesterone concentration to delay the onset of oestrus and synchronise returns-to-service. Plasma progesterone concentrations were measured before, during and following the resynchronisation treatment with a recycled CIDR device. Every enrolled cow (n=42) which had been initially synchronised using progesterone, prostaglandin F2a and oestradiol benzoate along with about 160 herd mates, had a recycled CIDR device re-inserted per vaginum 13 days after its first insemination. Most (n=30) of these cows were also injected with 1mg oestradiol benzoate (Group 2 & Group 3) at device re-insertion and every one of them was injected with the same dose of oestradiol benzoate 24 hours after device removal occurring 7 (Group 2) or 8 (Group 1 & Group 3) days after re-insertion. These variations in resynchronisation treatment did not affect any of the measured responses. There were two distinct populations of progesterone concentrations based on 4 blood samples taken 24 hours following device removal. The High progesterone sub-group (n=23) averaged 4.15 ng/mL (range=1.42 to 6.77 ng/mL); the Low progesterone sub-group (n= 19) averaged 0.08 ng/ml (range 0.03 to 0.14 ng/mL). Every one of the latter sub-group was detected in oestrus and inseminated from 24 to 96 hours after device removal. None of the animals in the former subgroup was detected in oestrus. However, 4 of these 23 animals (17%) were subsequently found to have not established a normal pregnancy, even though they had progesterone concentrations at 26 days after their first insemination which were indistinguishable from their 19 contemporaries who were confirmed pregnant to first insemination. These 4 cows were typical of those described as "Phantom Cows." In conclusion, resynchronisation treatment with a recycled device was effective in extending the oestrous cycle and stimulated return-to-service of animals with low plasma progesterone concentrations during the expected period of return within 96 hours after device removal. The treatment was less efficient at synchronising oestrus in animals which were retrospectively diagnosed not pregnant at pregnancy diagnosis 6 to 8 weeks after the conclusion of the Al period ("Phantom Cow Syndrome") but which had high plasma progesterone concentrations throughout the resynchronisation period. Experiment 3: To evaluate the reproductive responses of varied resynchronisation methods initiated during mid-dioestrus (Day 13 post-insemination) with progesterone and oestradiol benzoate to synchronise returns-to-service in cows which had initially received a standard treatment for anovulatory anoestrus; and to demonstrate the reproductive impact on the 6-week in-calf rate of these cows compared to their untreated cycling herd mates. A total of 810 cows which were diagnosed as anoestrus in 16 seasonally calving (3556 total cows) herds serviced by the Maffra Veterinary Clinic in 1998 were initially treated with progesterone by inserting a CIDR device for 6 days, and then injecting oestradiol benzoate (1mg) at 24 hours after device removal. Within 72 hours of this injection, 691 of these cows (85.3%) were detected in oestrus and inseminated. Each of these 691 cows had a recycled CIDR device re-inserted 16 days after initial device removal (13 � 1 day post-first insemination) and was also injected with 1mg oestradiol benzoate. The re-inserted device was withdrawn after 7 days. On the eighth day, half of these cows (n=334) were injected with 0.5mg oestradiol benzoate (2 x ODB; Group 2) while the other half (n=357) received no further treatment (1 x ODB; Group 1). a) The improved reproductive performance of cows in Group 2 occurred because more cows returned for a second insemination over the 4-day period following the second oestradiol benzoate injection (post-device removal) (44.6% versus 28.3%); b) the re-submission rate among cows subsequently confirmed as not conceiving to first insemination was greater (65.3% versus 40.1%); c) and the conception rates to first or second inseminations were similar for cows in the two Groups (1St = 29% versus. 32%; 2nd = 44.5% versus. 46.4%). The pregnancy rate for cows in Group 2 increased from 33.4% on Day 22 of inseminating to 55.4% by Day 26 compared to changes from 31.9% to 48.7% for cows in Group 1. The median interval from mating start date to conception for cows in the Group 2 was 23 days compared to 42 days for cows in Group 1 and 25 days for cycling herd mates. Comparable mean intervals to conception for these Groups were 31.2, 34.0 and 27.8 days respectively. Final in-calf figures for those animals in Group 2 were similar to those for cycling cows (86.5% versus. 85.4%), and higher than those for cows in Group 1 (82.9%; P<0.05). The results of this trial showed that the form of resynchronisation treatment had a significant effect on the outcome and the efficacy of treating cows for anovulatory anoestrus. In summary, this series of trials showed that: a) recycled CIDR devices released sufficient progesterone to resynchronise oestrus in previously synchronised cows; b) the resynchronisation treatments used in a Controlled Breeding Program achieved the desired objective among cows in which luteolysis had occurred spontaneously during the period of re-treatment without producing a false oestrus in cows with high plasma progesterone concentrations following resynchronisation; c) the resynchronisation treatment used in cows with anovulatory anoestrous requires oestradiol benzoate (0.5mg) to be injected after device removal to increase submission rates to the second insemination; and, d) that the resynchronisation treatment was ineffective with "Phantom Cows" Further studies are still required for improvement to be gained in the fertility of the first oestrus following hormonal treatment and the subsequent resynchronised inseminations of treated anovulatory anoestrous cows to achieve similar reproductive performance to their untreated cycling herd mates. In addition, a better understanding of the characteristics of the "Phantom Cow" following a first insemination is required to develop both management strategies and effective hormonal therapy to reduce their impact on herd fertility. These two factors combined are major limitations resulting in compromised reproductive performance in lactating Holstein cows in the commercial seasonally calving herds in Victoria.
Studies on resynchronisation of oestrus with progesterone and oestradiol benzoate in Holstein cows

Eagles, Vicki Maree. (University of Melbourne, 2000)

Resynchronisation of return-to-service in cows using progesterone and oestradiol benzoate is an integral part of current recommendations for Controlled Breeding Programs and the treatment of postpartum anovulatory anoestrus to improve herd reproductive performance. This thesis describes the results of a series of three experiments designed to test some of the hypotheses on the principles of resynchronisation based on each of the following questions: a) What concentrations of plasma progesterone are sustained by re-using a CIDR device for resynchronisation as compared to concentrations sustained by a new device? b) What proportion of the cows that are not confirmed pregnant to first insemination can be successfully resynchronised; and, do any pregnant cows show overt symptoms of oestrus as a consequence of the resynchronisation treatment? c) Does the type of the resynchronisation treatment for cows originally diagnosed with anovulatory anoestrus affect the efficacy of treating this common condition in Holstein cows? Experiment 1: To identify changes in plasma progesterone concentration, a sequence of treatments with a new or recycled CIDR device in ovariectomised cows was used to model the respective plasma progesterone profiles in treated cycling or anoestrous cows. A total of 9 ovariectomised non-lactating Holstein cows were each treated sequentially with a new CIDR device inserted for 6 days (Round 1); then a new CIDR device was inserted 4 days after the first device was withdrawn, with an insertion period of 6 days (Round 2); and finally, the same device initially used in Round 1 was re-inserted for a period of 7 days (Round 3). A 1mg oestradiol benzoate injection was administered 24 hours after device removal at the conclusion of each Round. Every cow was observed for signs of behavioural oestrus during the subsequent 72 h period. Blood samples were taken at specified intervals during the period of device insertion (3 hours, Day 1 and Day 6 post-insertion), as well as immediately preceding device insertion and following removal 6 or 7 days later. The average plasma progesterone concentrations over the 6-day insertion period for each Round 1, 2 and 3 were: 3.2, 2.2 and 1.7 ng/mL, respectively. Concentrations were significantly higher in Round 1 (P<0.01), but were similar in Rounds 2 and 3. The highest progesterone concentrations in Round 1 were those measured 3 and 24 hours after device insertion. This reflected the delay in the induction of hepatic enzymes that metabolise progesterone and are not normally required by ovariectomised cows. The progesterone content of a CIDR device declined by 23% (1.83g 1.41g) over the first 6 days of insertion and by a further 20% (1.41g -� 0.98g) over the second 7 days of insertion. Every cow displayed obvious overt symptoms of behavioural oestrus within 48 hours of being injected with oestradiol benzoate in each Round. In conclusion, ovariectomised cows were a suitable model to characterise subtle changes in the concentration of plasma progesterone which occurred in response to administration of a new or recycled CIDR device per vaginum for 6 or 7 days. The profile of changes in plasma progesterone as a consequence of device insertion and removal was rapid and was influenced by previous exposure to progesterone. Similar plasma progesterone profiles were associated with the use of a new CIDR device or a recycled device when animals had been previously exposed to elevated levels of progesterone. Experiment 2: The characterisation of the profile of changes in plasma progesterone concentration in response to a resynchronisation treatment initiated during middioestrus and subsequent to a synchronised first oestrus, in lactating Holstein cows involved in a commercial Controlled Breeding Program. It was also to determine if a recycled device could elevate plasma progesterone concentration to delay the onset of oestrus and synchronise returns-to-service. Plasma progesterone concentrations were measured before, during and following the resynchronisation treatment with a recycled CIDR device. Every enrolled cow (n=42) which had been initially synchronised using progesterone, prostaglandin F2a and oestradiol benzoate along with about 160 herd mates, had a recycled CIDR device re-inserted per vaginum 13 days after its first insemination. Most (n=30) of these cows were also injected with 1mg oestradiol benzoate (Group 2 & Group 3) at device re-insertion and every one of them was injected with the same dose of oestradiol benzoate 24 hours after device removal occurring 7 (Group 2) or 8 (Group 1 & Group 3) days after re-insertion. These variations in resynchronisation treatment did not affect any of the measured responses. There were two distinct populations of progesterone concentrations based on 4 blood samples taken 24 hours following device removal. The High progesterone sub-group (n=23) averaged 4.15 ng/mL (range=1.42 to 6.77 ng/mL); the Low progesterone sub-group (n= 19) averaged 0.08 ng/ml (range 0.03 to 0.14 ng/mL). Every one of the latter sub-group was detected in oestrus and inseminated from 24 to 96 hours after device removal. None of the animals in the former subgroup was detected in oestrus. However, 4 of these 23 animals (17%) were subsequently found to have not established a normal pregnancy, even though they had progesterone concentrations at 26 days after their first insemination which were indistinguishable from their 19 contemporaries who were confirmed pregnant to first insemination. These 4 cows were typical of those described as "Phantom Cows." In conclusion, resynchronisation treatment with a recycled device was effective in extending the oestrous cycle and stimulated return-to-service of animals with low plasma progesterone concentrations during the expected period of return within 96 hours after device removal. The treatment was less efficient at synchronising oestrus in animals which were retrospectively diagnosed not pregnant at pregnancy diagnosis 6 to 8 weeks after the conclusion of the Al period ("Phantom Cow Syndrome") but which had high plasma progesterone concentrations throughout the resynchronisation period. Experiment 3: To evaluate the reproductive responses of varied resynchronisation methods initiated during mid-dioestrus (Day 13 post-insemination) with progesterone and oestradiol benzoate to synchronise returns-to-service in cows which had initially received a standard treatment for anovulatory anoestrus; and to demonstrate the reproductive impact on the 6-week in-calf rate of these cows compared to their untreated cycling herd mates. A total of 810 cows which were diagnosed as anoestrus in 16 seasonally calving (3556 total cows) herds serviced by the Maffra Veterinary Clinic in 1998 were initially treated with progesterone by inserting a CIDR device for 6 days, and then injecting oestradiol benzoate (1mg) at 24 hours after device removal. Within 72 hours of this injection, 691 of these cows (85.3%) were detected in oestrus and inseminated. Each of these 691 cows had a recycled CIDR device re-inserted 16 days after initial device removal (13 � 1 day post-first insemination) and was also injected with 1mg oestradiol benzoate. The re-inserted device was withdrawn after 7 days. On the eighth day, half of these cows (n=334) were injected with 0.5mg oestradiol benzoate (2 x ODB; Group 2) while the other half (n=357) received no further treatment (1 x ODB; Group 1). a) The improved reproductive performance of cows in Group 2 occurred because more cows returned for a second insemination over the 4-day period following the second oestradiol benzoate injection (post-device removal) (44.6% versus 28.3%); b) the re-submission rate among cows subsequently confirmed as not conceiving to first insemination was greater (65.3% versus 40.1%); c) and the conception rates to first or second inseminations were similar for cows in the two Groups (1St = 29% versus. 32%; 2nd = 44.5% versus. 46.4%). The pregnancy rate for cows in Group 2 increased from 33.4% on Day 22 of inseminating to 55.4% by Day 26 compared to changes from 31.9% to 48.7% for cows in Group 1. The median interval from mating start date to conception for cows in the Group 2 was 23 days compared to 42 days for cows in Group 1 and 25 days for cycling herd mates. Comparable mean intervals to conception for these Groups were 31.2, 34.0 and 27.8 days respectively. Final in-calf figures for those animals in Group 2 were similar to those for cycling cows (86.5% versus. 85.4%), and higher than those for cows in Group 1 (82.9%; P<0.05). The results of this trial showed that the form of resynchronisation treatment had a significant effect on the outcome and the efficacy of treating cows for anovulatory anoestrus. In summary, this series of trials showed that: a) recycled CIDR devices released sufficient progesterone to resynchronise oestrus in previously synchronised cows; b) the resynchronisation treatments used in a Controlled Breeding Program achieved the desired objective among cows in which luteolysis had occurred spontaneously during the period of re-treatment without producing a false oestrus in cows with high plasma progesterone concentrations following resynchronisation; c) the resynchronisation treatment used in cows with anovulatory anoestrous requires oestradiol benzoate (0.5mg) to be injected after device removal to increase submission rates to the second insemination; and, d) that the resynchronisation treatment was ineffective with "Phantom Cows" Further studies are still required for improvement to be gained in the fertility of the first oestrus following hormonal treatment and the subsequent resynchronised inseminations of treated anovulatory anoestrous cows to achieve similar reproductive performance to their untreated cycling herd mates. In addition, a better understanding of the characteristics of the "Phantom Cow" following a first insemination is required to develop both management strategies and effective hormonal therapy to reduce their impact on herd fertility. These two factors combined are major limitations resulting in compromised reproductive performance in lactating Holstein cows in the commercial seasonally calving herds in Victoria.
Economic evaluation of feeding grain to dairy cows in Western Victoria

Kelly, Hugh D. (University of Melbourne, 1999)

This study is set in Western Victoria, where the dairy farming systems are characterized by springdominant pasture growth, low pasture growth in summer and moderate growth of pasture in autumn. This, coupled with either late winter calving or early autumn calving, creates pasture deficits, which occur in early and late lactation. The challenge for farmers in Western Victoria is to fill those feed gaps with supplements with the aim of maintaining or increasing profitability. Over a production year, feed supply is provided by a mix of fixed and variable inputs. Variable inputs such as working capital, fertilizers, seed, rainfall, irrigation, conserved fodders and concentrate feeds are added to the land, cows, labour and capital infrastructure. The worth of any one of these variable inputs is determined by the amount it contributes to the farm profitability during the production year. The aim of this study is to evaluate the economic effects of different grain feeding regimes on dairy farms in Western Victoria and determine whether net benefits could be gained from implementing a range of possible grain feeding regimes. Pasture based animal production systems are complicated because of the way the animals, water, pasture, fodder and concentrates interact during different stages of the production year. This means that both a short and medium term view has to be taken to make decisions about feed supply. There is also a need to evaluate the effect of unexpected changes to variable input supply and contingency measures that can be adopted to minimise negative impacts on the system. Further complications arise when trying to evaluate the changes to dairy farming systems because the production response function of each cow and the herd cannot be exactly known with great accuracy before the feed decisions are taken. As well, the law of diminishing marginal returns is at work all the time. The research undertaken in this project was based on a series of case studies of dairy farms in different areas throughout Western Victoria. These farms were selected to represent the different types of farming systems and areas within the region. The operation of the farms was studied at considerable depth to gain a thorough understanding of how each farming system operated. The operation of the farm was modeled using the dairy farm simulation program called UDDER, which can be used to simulate water-animal-pasture- fodder-concentrate interactions for different types of feeding strategies. Their effects on milk production over a year can be evaluated. A series of changes to the grain feeding regime were simulated on each farm to evaluate whether gains could be achieved from altering the timing and quantity of grain fed during the year. The technical information from the model UDDER was then analysed in an economic context using a partial budget model that was developed. This partial budget decision support tool helps farmers identify the essential feeding factors that affect the viability of a farming system and the relative merit of alternative grain feeding tactics and strategies. In this project it was identified that net gains could be made with strategic increases in grain feeding on the individual farming systems. Generally, if the grain fed to the dairy herd was increased during early and late lactation, extra gains were predicted to be achievable. However, substantial gains were also predicted if extra grain was fed to the herd during mid-lactation. When grain feeding levels were reduced, large losses were experienced. This indicates the reliance of the case study dairy herds on grain to produce milk if they are to maintain their current levels of profitability. This study shows that farmers may be able to earn larger profits with greater precision in quantity and timing of grain feeding. However, increases in some grain feeding will not always provide immediate extra gains. Like farm management in general, dairy feed management involves finding and mastering the key pieces of information and processing it in the whole farm context with both tactical and strategic perspectives in mind.
Economic evaluation of feeding grain to dairy cows in Western Victoria

Kelly, Hugh D. (University of Melbourne, 1999)

This study is set in Western Victoria, where the dairy farming systems are characterized by springdominant pasture growth, low pasture growth in summer and moderate growth of pasture in autumn. This, coupled with either late winter calving or early autumn calving, creates pasture deficits, which occur in early and late lactation. The challenge for farmers in Western Victoria is to fill those feed gaps with supplements with the aim of maintaining or increasing profitability. Over a production year, feed supply is provided by a mix of fixed and variable inputs. Variable inputs such as working capital, fertilizers, seed, rainfall, irrigation, conserved fodders and concentrate feeds are added to the land, cows, labour and capital infrastructure. The worth of any one of these variable inputs is determined by the amount it contributes to the farm profitability during the production year. The aim of this study is to evaluate the economic effects of different grain feeding regimes on dairy farms in Western Victoria and determine whether net benefits could be gained from implementing a range of possible grain feeding regimes. Pasture based animal production systems are complicated because of the way the animals, water, pasture, fodder and concentrates interact during different stages of the production year. This means that both a short and medium term view has to be taken to make decisions about feed supply. There is also a need to evaluate the effect of unexpected changes to variable input supply and contingency measures that can be adopted to minimise negative impacts on the system. Further complications arise when trying to evaluate the changes to dairy farming systems because the production response function of each cow and the herd cannot be exactly known with great accuracy before the feed decisions are taken. As well, the law of diminishing marginal returns is at work all the time. The research undertaken in this project was based on a series of case studies of dairy farms in different areas throughout Western Victoria. These farms were selected to represent the different types of farming systems and areas within the region. The operation of the farms was studied at considerable depth to gain a thorough understanding of how each farming system operated. The operation of the farm was modeled using the dairy farm simulation program called UDDER, which can be used to simulate water-animal-pasture- fodder-concentrate interactions for different types of feeding strategies. Their effects on milk production over a year can be evaluated. A series of changes to the grain feeding regime were simulated on each farm to evaluate whether gains could be achieved from altering the timing and quantity of grain fed during the year. The technical information from the model UDDER was then analysed in an economic context using a partial budget model that was developed. This partial budget decision support tool helps farmers identify the essential feeding factors that affect the viability of a farming system and the relative merit of alternative grain feeding tactics and strategies. In this project it was identified that net gains could be made with strategic increases in grain feeding on the individual farming systems. Generally, if the grain fed to the dairy herd was increased during early and late lactation, extra gains were predicted to be achievable. However, substantial gains were also predicted if extra grain was fed to the herd during mid-lactation. When grain feeding levels were reduced, large losses were experienced. This indicates the reliance of the case study dairy herds on grain to produce milk if they are to maintain their current levels of profitability. This study shows that farmers may be able to earn larger profits with greater precision in quantity and timing of grain feeding. However, increases in some grain feeding will not always provide immediate extra gains. Like farm management in general, dairy feed management involves finding and mastering the key pieces of information and processing it in the whole farm context with both tactical and strategic perspectives in mind.

School of Agriculture, Food and Ecosystem Sciences - Theses

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