https://hdl.handle.net/10182/1 2018-01-21T10:52:08Z 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. 2017-01-01T00:00:00Z 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. 2012-01-01T00:00:00Z https://hdl.handle.net/10182/8893 The application of high-resolution atmospheric modelling to weather and climate variability in vineyard regions Sturman, A.; Zawar-Reza, P.; Soltanzadeh, I.; Katurji, M.; Bonnardot, V.; Parker, Amber; Trought, Michael C.; Quénol, H.; Le Roux, R.; Gendig, E.; Schulmann, T. Grapevines are highly sensitive to environmental conditions, with variability in weather and climate (particularly temperature) having a significant influence on wine quality, quantity and style. Improved knowledge of spatial and temporal variations in climate and their impact on grapevine response allows better decision-making to help maintain a sustainable wine industry in the context of medium to long term climate change. This paper describes recent research into the application of mesoscale weather and climate models that aims to improve our understanding of climate variability at high spatial (1 km and less) and temporal (hourly) resolution within vineyard regions of varying terrain complexity. The Weather Research and Forecasting (WRF) model has been used to simulate the weather and climate in the complex terrain of the Marlborough region of New Zealand. The performance of the WRF model in reproducing the temperature variability across vineyard regions is assessed through comparison with automatic weather stations. Coupling the atmospheric model with bioclimatic indices and phenological models (e.g. Huglin, cool nights, Grapevine Flowering Véraison model) also provides useful insights into grapevine response to spatial variability of climate during the growing season, as well as assessment of spatial variability in the optimal climate conditions for specific grape varieties. 2017-05-15T00:00:00Z https://hdl.handle.net/10182/8889 Ammonium sorption and ammonia inhibition of nitrite-oxidizing bacteria explain contrasting soil N₂O production Venterea, R. T.; Clough, Timothy J.; Coulter, J. A.; Breuillin-Sessoms, F.; Wang, P.; Sadowsky, M. J. Better understanding of process controls over nitrous oxide (N₂O) production in urine-impacted 'hot spots' and fertilizer bands is needed to improve mitigation strategies and emission models. Following amendment with bovine (Bos taurus) urine (Bu) or urea (Ur), we measured inorganic N, pH, N₂O, and genes associated with nitrification in two soils ('L' and 'W') having similar texture, pH, C, and C/N ratio. Solution-phase ammonia (slNH₃) was also calculated accounting for non-linear ammonium (NH₄⁺) sorption capacities (ASC). Soil W displayed greater nitrification rates and nitrate (NO₃⁻) levels than soil L, but was more resistant to nitrite (NO₂⁻) accumulation and produced two to ten times less N₂O than soil L. Genes associated with NO₂⁻oxidation (nxrA) increased substantially in soil W but remained static in soil L. Soil NO₂⁻was strongly correlated with N₂O production, and cumulative (c-) slNH₃ explained 87% of the variance in c-NO₂⁻. Differences between soils were explained by greater slNH₃ in soil L which inhibited NO₂⁻oxidization leading to greater NO₂⁻ levels and N₂O production. This is the first study to correlate the dynamics of soil slNH₃, NO₂⁻, N₂O and nitrifier genes, and the first to show how ASC can regulate NO₂⁻ levels and N₂O production. © 2015 Macmillan Publishers Limited. 2015-07-16T00:00:00Z