Thesis (Ph. D.)--University of Adelaide, Dept. of Animal Sciences, 1995? / Includes bibliographical references (leaves 175-196).

Genomic selection (GS) has been adopted by the dairy cattle breeding industry and the opportunity exists to implement this technology in UK beef and sheep breeding. However, these sectors do not appear so readily predisposed to GS implementation. Following an introduction to GS in Chapter 1, Chapter 2 investigated the structure of the little-studied UK beef breeding sector. This provided estimates of key commercial and pedigree population parameters, for use in modelling genetic gain from GS. Terminal traits were found to be the dominant selection goals, with 85% of beef-sired commercial matings resulting in progeny being slaughtered at a prime age. Pedigree bulls disseminated the majority of genes in the sector via natural service. The correlation between the terminal selection index (TI) and the sale price of breeding bulls was moderate, suggesting a modest uptake of genetic technology in the sector. Chapter 3 estimated selection intensity for TI, generation interval and the dissemination rate of improved genes in the pedigree Limousin population. In order to predict the genetic gain achievable in using GS in beef and sheep breeding, Chapters 4 to 6 undertook deterministic selection index simulations, incorporating genomic information as correlated traits. In Chapter 4, GS was modelled for terminal beef traits, when incorporating carcass information and accounting for likely genotype by environment interaction. Using a training population of 2000 sires, this concept was predicted to offer 40% greater genetic gain than existing BLUP selection using pedigree phenotypes. Gene flow methodology projected the commercial value of this gain to offer a substantial return net of genotyping costs. Chapter 5 explored GS for maternal beef traits within the concept of a nucleus breeding scheme. Whilst greater genetic gain was predicted with GS than with conventional BLUP, the economic value of this gain was projected to be too low to justify such a scheme in the UK. Chapter 6 proposed a synergy between computer tomography (CT) phenotypes and GS in sheep breeding. Developing a genomic predictor from male selection candidates with CT phenotypes and conventional performance records was predicted to increase genetic gain by 55% over BLUP selection without CT traits. Introducing GBV contributed most of the accuracy in this scenario, suggesting that the existing performance recording structure in UK sheep breeding could in the future be replaced by GS using CT. In the general discussion, the potential for GS in other beef and sheep traits was considered in the light of the outcomes of these simulations. Given the lack of vertical integration in UK beef and sheep sectors, the drivers for implementation of GS are examined. Finally, the options for international cooperation and the possibilities offered by future genotyping technology are considered. It was concluded that implementation of GS incorporating beef carcass phenotypes was merited and could provide a platform for future GS implementation in other novel traits. Sheep GS with CT traits was considered a higher risk strategy, due to the lack of evidence for uptake of existing EBV technology.

No description available.

THESIS ABSTRACT Current control strategies for livestock ectoparasites are limited by problems associated with chemical resistance and residues. Fungal biopesticides could provide an alternative control without these problems. However, a strategic approach is needed to first evaluate the suitability of selected fungal isolates for fungal biopesticide development. Two ectoparasites of significance to cattle and sheep are the cattle tick Rhipicephalus (Boophilus) microplus (Canestrini) and the Australian sheep blowfly Lucilia cuprina (Wiedmann). The fungus Metarhizium anisopliae (Metsch.) Sorokin) was evaluated for its potential to control these livestock ectoparasites. The growth characteristics of 30 isolates of M. anisopliae were investigated. Radial growth measurements were used to identify vigorous isolates that grew well at 30C and were capable of growing at 35C. A qualitative assessment of sporulation capacity further refined the candidate isolate group. A possible nutritive role of oil in the formulation was also investigated. However, there was no clear support for the theory that oil as a formulation additive could boost the germination and growth of the fungal conidia in vitro. Quantal response bioassays were conducted with cattle ticks and sheep blowflies using a range of conidial doses of three different isolates of M. anisopliae and different methods of inoculation. Ticks were either dosed with 2 µl or immersed in the conidial doses. Blowflies were either dosed with 2 µl of the conidial doses or fed conidia mixed with sugar. Probit analyses were carried out on the mortality data to compare the virulence of these isolates to ticks and blowflies and look for indications of different virulence mechanisms employed by M. anisopliae isolates when invading these hosts. One isolate (ARIM16) showed high virulence to both hosts killing 95 % of ticks after two days and 88 (±2) % of blowflies after four days. Strikingly different mortality patterns indicated quite different virulence mechanisms operating when M. anisopliae invades ticks or blowflies. The mortality pattern seen with ticks suggested that the number of conidia adhering per unit area of the cuticle was more important for rapid tick death than the total number of conidia contacting the entire tick surface. Blowflies fed conidia mixed with food died rapidly after an initial lag phase regardless of dose. Microscopic investigations were carried out to resolve the basis of the virulence patterns observed. The spatial and temporal aspects of the invasion of ticks and blowflies by M. anisopliae isolate ARIM16 were investigated with different types of microscopy. The scanning electron microscope and stereo light microscope were used to record surface changes and events and the compound light microscope revealed internal changes. Two distinctly different patterns of invasion were found in ticks and blowflies. Fungal conidia germinated on the surface of ticks then hyphae simultaneously penetrated into the tick body and grew across the tick surface. There was extensive fungal degradation of the tick cuticle with a preference for the outer endocuticle. While large numbers of conidia adhered to the surface of blowflies, no conidia were recorded germinating on external surfaces. One germinating conidium was seen in the entrance to the buccal cavity. Investigations of the fly interior revealed a higher density of hyphal bodies in the haemolymph surrounding the buccal cavity than in haemolymph from regions of the upper thorax. This pattern suggested that fungal invasion of the blowfly is through the buccal cavity. Plentiful extracellular mucilage was seen around the hyphae on ticks, and crystals of calcium oxalate were seen amongst the hyphae on the surface of ticks and in the haemolymph of blowflies killed by M. anisopliae isolate ARIM16. It was considered that cattle ticks are more suited for control with fungal biopesticides than adult blowflies. Three field trials were conducted over twelve months to assess the pathogenicity of M. anisopliae to parasitic stages of R. microplus on dairy heifers under different environmental conditions. Two isolates were selected based on their high optimal growth temperature (30oC), good conidial production characteristics and ability to kill adult engorged ticks in the laboratory in minimum time. Conidia were formulated in an oil emulsion and applied using a motor driven spray unit. Surface temperatures of selected animals were monitored, as were the ambient temperature and relative humidity. Unengorged ticks sampled from each animal immediately after treatment were incubated under laboratory conditions to assess the efficacy of the formulation and application. Egg production by engorged ticks collected in the first 3 days after treatment was monitored. Side counts of standard adult female ticks were conducted daily, before and after treatment to assess the performance of the fungus against all tick stages on the animals. At each trial the formulation caused 100% mortality in unengorged ticks that were removed from cattle and cultured under laboratory conditions. A significant reduction in egg production was recorded for engorged ticks collected in the three days post treatment. In the field, the fungal formulation had an inconsistent effect on ticks, which might be due to the influence of environmental temperature and humidity.

THESIS ABSTRACT Current control strategies for livestock ectoparasites are limited by problems associated with chemical resistance and residues. Fungal biopesticides could provide an alternative control without these problems. However, a strategic approach is needed to first evaluate the suitability of selected fungal isolates for fungal biopesticide development. Two ectoparasites of significance to cattle and sheep are the cattle tick Rhipicephalus (Boophilus) microplus (Canestrini) and the Australian sheep blowfly Lucilia cuprina (Wiedmann). The fungus Metarhizium anisopliae (Metsch.) Sorokin) was evaluated for its potential to control these livestock ectoparasites. The growth characteristics of 30 isolates of M. anisopliae were investigated. Radial growth measurements were used to identify vigorous isolates that grew well at 30C and were capable of growing at 35C. A qualitative assessment of sporulation capacity further refined the candidate isolate group. A possible nutritive role of oil in the formulation was also investigated. However, there was no clear support for the theory that oil as a formulation additive could boost the germination and growth of the fungal conidia in vitro. Quantal response bioassays were conducted with cattle ticks and sheep blowflies using a range of conidial doses of three different isolates of M. anisopliae and different methods of inoculation. Ticks were either dosed with 2 µl or immersed in the conidial doses. Blowflies were either dosed with 2 µl of the conidial doses or fed conidia mixed with sugar. Probit analyses were carried out on the mortality data to compare the virulence of these isolates to ticks and blowflies and look for indications of different virulence mechanisms employed by M. anisopliae isolates when invading these hosts. One isolate (ARIM16) showed high virulence to both hosts killing 95 % of ticks after two days and 88 (±2) % of blowflies after four days. Strikingly different mortality patterns indicated quite different virulence mechanisms operating when M. anisopliae invades ticks or blowflies. The mortality pattern seen with ticks suggested that the number of conidia adhering per unit area of the cuticle was more important for rapid tick death than the total number of conidia contacting the entire tick surface. Blowflies fed conidia mixed with food died rapidly after an initial lag phase regardless of dose. Microscopic investigations were carried out to resolve the basis of the virulence patterns observed. The spatial and temporal aspects of the invasion of ticks and blowflies by M. anisopliae isolate ARIM16 were investigated with different types of microscopy. The scanning electron microscope and stereo light microscope were used to record surface changes and events and the compound light microscope revealed internal changes. Two distinctly different patterns of invasion were found in ticks and blowflies. Fungal conidia germinated on the surface of ticks then hyphae simultaneously penetrated into the tick body and grew across the tick surface. There was extensive fungal degradation of the tick cuticle with a preference for the outer endocuticle. While large numbers of conidia adhered to the surface of blowflies, no conidia were recorded germinating on external surfaces. One germinating conidium was seen in the entrance to the buccal cavity. Investigations of the fly interior revealed a higher density of hyphal bodies in the haemolymph surrounding the buccal cavity than in haemolymph from regions of the upper thorax. This pattern suggested that fungal invasion of the blowfly is through the buccal cavity. Plentiful extracellular mucilage was seen around the hyphae on ticks, and crystals of calcium oxalate were seen amongst the hyphae on the surface of ticks and in the haemolymph of blowflies killed by M. anisopliae isolate ARIM16. It was considered that cattle ticks are more suited for control with fungal biopesticides than adult blowflies. Three field trials were conducted over twelve months to assess the pathogenicity of M. anisopliae to parasitic stages of R. microplus on dairy heifers under different environmental conditions. Two isolates were selected based on their high optimal growth temperature (30oC), good conidial production characteristics and ability to kill adult engorged ticks in the laboratory in minimum time. Conidia were formulated in an oil emulsion and applied using a motor driven spray unit. Surface temperatures of selected animals were monitored, as were the ambient temperature and relative humidity. Unengorged ticks sampled from each animal immediately after treatment were incubated under laboratory conditions to assess the efficacy of the formulation and application. Egg production by engorged ticks collected in the first 3 days after treatment was monitored. Side counts of standard adult female ticks were conducted daily, before and after treatment to assess the performance of the fungus against all tick stages on the animals. At each trial the formulation caused 100% mortality in unengorged ticks that were removed from cattle and cultured under laboratory conditions. A significant reduction in egg production was recorded for engorged ticks collected in the three days post treatment. In the field, the fungal formulation had an inconsistent effect on ticks, which might be due to the influence of environmental temperature and humidity.

The study was conducted across the four district municipalities in the Free State province of South Africa. The objective of the study was to determine socio-economic factors that affected livestock numbers among smallholder cattle and sheep farmers in the Free State province of South Africa. The research was qualitative and quantitative in nature. Proportionate random sampling method was used to collect data. The population comprised of smallholder cattle and sheep farmers that kept at least 30 livestock. Data between the 2008 and 2012 farming seasons were collected by administering well-structured questionnaires to 250 smallholder cattle and sheep farmers. Data collected were captured and analysed using the statistical package for social sciences (SPSS version 22 of 2013) to obtain frequency, cross-tabulation, descriptive statistics and ordinary least square (OLS) regression. Descriptive statistics results indicated that lack of camp systems, drought prevalence, increased feed costs, poor veterinary interventions, insufficient breeding stock, high cost of fuel and transportation, lack of equipment, diseases, stock theft and pilfering, and insufficient grazing land were the prevalent factors that affected cattle and sheep farming in the province.The OLS regression results indicated that the variables that significantly affected livestock numbers were district, household size, livestock numbers in 2008, planted pastures, grazing land condition, grazing land acquisition, service, advice / training, veterinary services, purchase of dosing products and sales per year. The results also indicated that the majority (96.8%) of the smallholder cattle and sheep farmers would like to increase their livestock numbers. It was therefore recommended that extension and veterinary services should be strengthened in the study area. In addition, it was recommended that smallholder livestock farmers should be encouraged to plant pastures to reduce pressure on the natural veld and make forage available throughout the year. Lastly, as a recommendation, government should provide subsidies with distribution policies that will ensure that all smallholder livestock farmers can benefit. / Agriculture and  Animal Health / M. Sc. (Agriculture)

The study was conducted across the four district municipalities in the Free State province of South Africa. The objective of the study was to determine socio-economic factors that affected livestock numbers among smallholder cattle and sheep farmers in the Free State province of South Africa. The research was qualitative and quantitative in nature. Proportionate random sampling method was used to collect data. The population comprised of smallholder cattle and sheep farmers that kept at least 30 livestock. Data between the 2008 and 2012 farming seasons were collected by administering well-structured questionnaires to 250 smallholder cattle and sheep farmers. Data collected were captured and analysed using the statistical package for social sciences (SPSS version 22 of 2013) to obtain frequency, cross-tabulation, descriptive statistics and ordinary least square (OLS) regression. Descriptive statistics results indicated that lack of camp systems, drought prevalence, increased feed costs, poor veterinary interventions, insufficient breeding stock, high cost of fuel and transportation, lack of equipment, diseases, stock theft and pilfering, and insufficient grazing land were the prevalent factors that affected cattle and sheep farming in the province.The OLS regression results indicated that the variables that significantly affected livestock numbers were district, household size, livestock numbers in 2008, planted pastures, grazing land condition, grazing land acquisition, service, advice / training, veterinary services, purchase of dosing products and sales per year. The results also indicated that the majority (96.8%) of the smallholder cattle and sheep farmers would like to increase their livestock numbers. It was therefore recommended that extension and veterinary services should be strengthened in the study area. In addition, it was recommended that smallholder livestock farmers should be encouraged to plant pastures to reduce pressure on the natural veld and make forage available throughout the year. Lastly, as a recommendation, government should provide subsidies with distribution policies that will ensure that all smallholder livestock farmers can benefit. / Agriculture and  Animal Health / M. Sc. (Agriculture)

This study focused on the impact of climate change and adaptation on small-scale cattle and sheep farming in the Eastern Cape province of South Africa. Using information from 500 livestock farmers between 2005 and 2009 farming season, three methods of analysis were used to determine impacts of climate change and adaptation. They were Principal Component Analysis (PCA), Binary Logistic Regression Model (BLRM) and Heckman Probit Model (HPM). Findings revealed that cattle production decreased during the study period 2005 to 2009. Preliminary descriptive statistics results indicated that farmers had different perceptions on climate change and adaptation measures between the periods 2005 and 2009. Further analysis using PCA showed that the different perceptions could be grouped into: (i) drought and windy weather patterns; (ii) information and adaptation; (iii) climate change extension services; (iv) intensive cattle and sheep production; and (v) temperatures. The results of the BLRM indicated that the most significant factors that affected climate change and adaptation were: (i) non-farm income per annum; (ii) type of weather perceived from 2005 to 2009; (iii) livestock production and ownership; (iv) distance to weather stations; (v) distance to input markets; (vi) adaptation strategies and (vii) annual average temperature. From the HPM the results indicated that marital status, level of education, formal extension, temperatures and the way in which land was acquired, significantly affected awareness on climate change. Variables that significantly affected adaptation selections were gender, formal extension, information received on climate change, temperatures and the way in which land was acquired.It was concluded that in the area of study, change in climate was already perceived by small-scale cattle and sheep farmers. Households that perceived differences in seasonal temperatures during the survey period were less likely to adapt to climate change. Having access to extension services increased the likelihood of adaptation to climate change. Information on climate change to improve livestock production appeared to play a significant role in the selection of adaptation measures. The recommendation was that government should consider cattle and sheep farmers’ perceptions on climate change when deciding on programmes for cattle and sheep production. It further suggested that the most significant factors that affected climate change, adaptation, and awareness and adaptation selections be considered when adaptation programmes are planned. / Agriculture Animal Health and Human Ecology / D.Phil. (Environmental Management)

This study focused on the impact of climate change and adaptation on small-scale cattle and sheep farming in the Eastern Cape province of South Africa. Using information from 500 livestock farmers between 2005 and 2009 farming season, three methods of analysis were used to determine impacts of climate change and adaptation. They were Principal Component Analysis (PCA), Binary Logistic Regression Model (BLRM) and Heckman Probit Model (HPM). Findings revealed that cattle production decreased during the study period 2005 to 2009. Preliminary descriptive statistics results indicated that farmers had different perceptions on climate change and adaptation measures between the periods 2005 and 2009. Further analysis using PCA showed that the different perceptions could be grouped into: (i) drought and windy weather patterns; (ii) information and adaptation; (iii) climate change extension services; (iv) intensive cattle and sheep production; and (v) temperatures. The results of the BLRM indicated that the most significant factors that affected climate change and adaptation were: (i) non-farm income per annum; (ii) type of weather perceived from 2005 to 2009; (iii) livestock production and ownership; (iv) distance to weather stations; (v) distance to input markets; (vi) adaptation strategies and (vii) annual average temperature. From the HPM the results indicated that marital status, level of education, formal extension, temperatures and the way in which land was acquired, significantly affected awareness on climate change. Variables that significantly affected adaptation selections were gender, formal extension, information received on climate change, temperatures and the way in which land was acquired.It was concluded that in the area of study, change in climate was already perceived by small-scale cattle and sheep farmers. Households that perceived differences in seasonal temperatures during the survey period were less likely to adapt to climate change. Having access to extension services increased the likelihood of adaptation to climate change. Information on climate change to improve livestock production appeared to play a significant role in the selection of adaptation measures. The recommendation was that government should consider cattle and sheep farmers’ perceptions on climate change when deciding on programmes for cattle and sheep production. It further suggested that the most significant factors that affected climate change, adaptation, and awareness and adaptation selections be considered when adaptation programmes are planned. / Agriculture Animal Health and Human Ecology / D.Phil. (Environmental Management)