http://researcharchive.lincoln.ac.nz:80 The Research Archive digital repository system captures, stores, indexes, preserves, and distributes digital research material. Fri, 19 Jan 2018 19:40:18 GMT 2018-01-19T19:40:18Z https://hdl.handle.net/10182/8904 In vitro fermentation characteristics of ryegrass-white clover sward containing different proportions of chicory Al-Marashdeh, Omar; Cheng, L.; Gregorini, Pablo; Edwards, Grant Chicory (Cichorum intybus) is a deep-rooted grazeable forage used to overcome production and nutritive value shortfalls of perennial ryegrass (Loliun perenne) and white clover (Trifolium repens) swards during summer drought periods in New Zealand. Despite the wide use of chicory, limited data is available on its fermentation characteristics, and how those affect rumen fermentation pattern and, thereby, nutrient supply from ryegrass-white clover based swards including chicory. The objective of this study was to evaluate the in vitro fermentation characteristics of ryegrass-white clover sward containing different proportions of chicory. Herbages containing 100% ryegrass-white clover (Ch0); 25% chicory + 75% ryegrass-white clover (Ch25%); 50% chicory + 50% ryegrass-white clover (Ch50%); and 100% chicory (Ch100%) were incubated using the Daisy II-200/220 incubator (ANKOM Technology, NY). Treatments, Ch0, 25%, 50% and 100%, were randomly assigned to the four fermentation jars over two runs. The pH, volatile fatty acids and ammonia-N concentrations of fermentation liquor were measured at 4, 8, 12, 24 and 48 hours of incubation. Data were analysed using repeated measures ANOVA with chicory proportion as treatment effect, incubation time as time effect and run as replicate. The pH, mean concentration of ammonia-N, propionate, acetate and butyrate were not affected by treatment (P > 0.05), averaging at 6.5 ± 0.02, 19.1 ± 1.98, 5.3±1.12, 20.2 ± 3.37and 3.3 ± 0.66 mmol/l, respectively. Current results showed that fermentation pattern of herbage containing increasing proportions of chicory is similar to the ‘conventional’ ryegrass-white clover, suggesting that including chicory in conventional swards might not alter the nutritive value of herbage. Sun, 01 Jan 2017 00:00:00 GMT https://hdl.handle.net/10182/8904 2017-01-01T00:00:00Z https://hdl.handle.net/10182/8903 Intraspecific variation in indirect plant-soil feedbacks as a driver of a wetland plant invasion Allen, Warwick; Meyerson, L. A.; Flick, A. J.; Cronin, J. T. Plant-soil feedbacks (PSFs) can influence plant competition via direct interactions with pathogens and mutualists or indirectly via apparent competition/mutualisms (i.e., spillover to co-occurring plants) and soil legacy effects. Presently, it is unknown how intraspecific variation in PSFs interacts with the environment (e.g., nutrient availability) to influence competition between native and invasive plants. We conducted a fully crossed multi-factor greenhouse experiment to determine the effects of soil biota, interspecific competition, and nutrient availability on biomass of replicate populations from one native and two invasive lineages of common reed (Phragmites australis) and a single lineage of native smooth cordgrass (Spartina alterniflora). Harmful soil biota consistently dominated PSFs involving all three P. australis lineages, reducing biomass by 10%, regardless of nutrient availability or S. alterniflora presence as a competitor. Spillover of soil biota derived from the rhizosphere of the two invasive P. australis lineages reduced S. alterniflora biomass by 7%, whereas soil biota from the native P. australis lineage increased S. alterniflora biomass by 6%. Interestingly, regardless of lineage, P. australis soil biota negatively affected S. alterniflora biomass when grown alone (i.e., a soil legacy), but had a positive impact when grown with P. australis, suggesting that P. australis is preferred by harmful generalist soil biota or facilitates S. alterniflora via spillover (i.e., apparent mutualism). Soil biota also reduced the negative impacts of interspecific competition on S. alterniflora by 13%, although it remained competitively inferior to P. australis across all treatments. Moreover, competitive interactions and the response to nutrients did not differ among P. australis lineages, indicating that interspecific competition and nutrient deposition may not be key drivers of P. australis invasion in North America. Taken together, although soil biota, interspecific competition, and nutrient availability appear to have no direct impact on the success of invasive P. australis lineages in North America, indirect spillover and soil legacies from P. australis occur and may have important implications for co-occurring native species and restoration of invaded habitats. Our study integrates multiple factors linked to plant invasions, highlighting that indirect interactions are likely commonplace in driving successful invasions and their impacts on the local community. Fri, 07 Jul 2017 00:00:00 GMT https://hdl.handle.net/10182/8903 2017-07-07T00:00:00Z https://hdl.handle.net/10182/8899 Valuing conservation benefits of disease control in wildlife: a choice experiment approach to bovine tuberculosis management in New Zealand's native forests Tait, Peter R.; Saunders, Caroline M.; Nugent, Graham; Rutherford, Paul We assess the non-monetary environmental benefits that accrue incidentally in New Zealand (NZ) from pest management conducted primarily to control an animal disease, bovine tuberculosis (TB). TB is an infectious disease that is one of the world's most serious animal health problems and, in many parts of the developing world, still a major mortality risk for humans. The incidence of TB in New Zealand (NZ) farmed livestock has been reduced progressively over the last 20 years, largely due to extensive and sustained population control of the main wildlife reservoir of disease, the introduced brushtail possum. Possums are also major pests that threaten indigenous forest biodiversity, and so extensive possum control for TB mitigation also incidental benefits conservation, but the extent and public value of this benefit has yet to be quantified. We conducted a choice experiment survey of the NZ public in an effort to value the native forest biodiversity benefits of TB-related possum control. We find strong public support for conservation outcomes consequent to TB-possum control in public native forests. The public place substantial value on the most observable biodiversity benefits of TB possum control, such as improved forest canopies and presence of native birds. The benefits, costs and values of TB-possum control are discussed in relation to the future directives of NZ's TB control programme, which is headed toward first regional and then national level disease eradication. Wed, 15 Mar 2017 00:00:00 GMT https://hdl.handle.net/10182/8899 2017-03-15T00:00:00Z https://hdl.handle.net/10182/8896 Are faecal egg counts approaching their 'sell-by' date? Greer, Andrew W.; Sykes, Andrew R. Historically, the primary determinant for the state of parasitism has been the concentration of nematode eggs in the faeces (FEC). This descriptor has a number of limitations that have implications for the development of drug resistance and hamper the identification of resilient livestock. A major fallacy is that FEC can reliably assess the worm burden, the need for anthelmintic and the efficacy of that treatment. FEC is a ratio, eggs per gram of faeces, not a quantity. Not only is the denominator ignored but interpretation of the numerator requires knowledge of nematode species present and female fecundity which can be affected by infra-population dynamics. By definition, a parasite exists at the expense of its host. As such, the consistent ability of resilient animals to maintain performance, despite a high FEC, strongly suggests that FEC does not provide a reliable indicator of the cost of parasitism. This manuscript reviews the factors that affect FEC and argues for a step change in our approach to the control of nematode parasitism in pastoral systems to one focused on individual treatments based on animal performance utilising radio-frequency electronic identification and automated weighing and drafting systems. Sun, 01 Jan 2012 00:00:00 GMT https://hdl.handle.net/10182/8896 2012-01-01T00:00:00Z