Research@Lincoln
Research@Lincoln is an open access institutional repository collecting the research produced by Lincoln University staff and students. You may also be interested in Data@Lincoln or Lincoln University Living Heritage.
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Item Restricted Ovine KRT81 variants and their influence on selected wool traits of commercial value(MDPI, 2024-06)Keratins are the main structural protein components of wool fibres, and variation in them and their genes (KRTs) is thought to influence wool structure and characteristics. The PCR–single strand conformation polymorphism technique has been used previously to investigate genetic variation in selected coding and intron regions of the type II sheep keratin gene KRT81, but no variation was identified. In this study, we used the same technique to explore the 5′ untranslated region of KRT81 and detected three sequence variants (A, B and C) that contain four single nucleotide polymorphisms. Among the 389 Merino × Southdown cross sheep investigated, variant B was linked to a reduction in clean fleece weight, while C was associated with an increase in both greasy fleece weight and clean fleece weight. No discernible effects on staple length or mean-fibre-diameter-related traits were observed. These findings suggest that variation in ovine KRT81 might influence wool growth by changing the density of wool follicles in the skin, the density of individual fibres, or the area of the skin producing fibre, as opposed to changing the rate of extrusion of fibres or their diameter.Publication Open Access Ryegrass endophyte mixtures for improved animal health : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University(Lincoln University, 2024)In New Zealand, perennial ryegrass (Lolium perenne) with endophyte (Epichloë festucae var. lolii) is a standard ingredient of pastures where insect pests challenge the persistence of the ryegrass. Farmers currently have multiple ryegrass cultivar x endophyte strain combinations from which to choose the best match for their requirements. However, no single cultivar x strain combination provides both the highest insect protection and lowest occurrence of ryegrass staggers and heat stress in animals grazing pasture with endophyte. Furthermore, the current industry protocol for testing the safety of animals grazing a grass x endophyte combination involves exposing the animals to a simulated worst- case scenario and needs reassessment. This research aimed to examine the effects of endophyte diversity in perennial ryegrass on the health and performance of sheep using a modelling approach so that an animal response of any mixture could be predicted as a function of the mixture’s endophyte proportions, thus minimising the need for animal testing in the future. At Barenbrug Plant Breeding Station, Courtenay, Canterbury, eight pasture treatments of Maxsyn perennial ryegrass – seven that varied widely in sown proportions of three endophyte strains – nea3, nea12, and standard endophyte (SE) – and an endophyte-free control (nil), were tested over four experimental runs from February 2020 to December 2021. There were three monocultures (100% of each strain), three binary mixtures (50% of each of two strains) and one ternary mixture (33.3% of each strain) of endophyte based on a simplex centroid design. The eight treatments were randomised in three blocks of 0.156-ha plots. The animal responses of interest were ryegrass staggers, liveweight gain, heat stress, and diet selection of grazing sheep. The first experiment run was a test for ryegrass staggers in February 2020. Endophyte toxicity in late summer is typically near its annual maximum in Canterbury, so the timing of this run created a ‘worst-case scenario’ for ryegrass staggers. The pastures were managed in the previous spring so as to accumulate a large herbage dry matter (DM) mass (about 3700 kg DM/ha above a cutting height of 40–50 mm) of low nutritive quality feed (metabolisable energy (ME) = 8.7 MJ/kg DM and crude protein (CP) = 4.9%). The pasture available (kg DM/ha) was high enough for lambs to remain in the same plots for a 4-week testing period at a stocking rate of 64.1 lambs/ha. Ryegrass staggers was severe (score 4–5) in the lambs grazing the SE pasture after 8 days and in all other endophyte monocultures and mixtures after 22 days. Mixture models fitted to the staggers response data predicted the staggers score for any combination of sown endophyte proportions and identified an optimum of 65% nea3 and 35% nea12 which delayed severe staggers by 1 week. Ryegrass staggers was associated with tremorgenic alkaloids in the herbage above 40–50 mm: epoxy-janthitrem I of nea12 (1 ppm), paxilline and terpendole C of nea3 (0.1 and 1.2 ppm), and lolitrem B, paxilline and terpendole C of SE (2.2, 0.2, and 1.1 ppm). The second experimental run was a study of liveweight gain and ryegrass staggers under low toxicity conditions from September to December 2020. The spring pastures provided optimal conditions for liveweight gain and the stocking rate was kept consistent at 44.9 hoggets/ha. Pre-grazing pasture mass was ca. 1600 kg DM/ha, ME was 12 MJ/kg DM and CP was 20% above 40–50 mm. The average daily gain for all mixtures was 271 g/day over the first 4 weeks, and 20 g/day for weeks 4–8. The mixture models fitted to the liveweight gain data identified the optimum endophyte formulation that maximised liveweight gain to be a monoculture of nea12 so that the responses were equal to the monoculture performance in the first and second 4 weeks of grazing (292 and 25 g/day). Ergovaline, the alkaloid linked to suppressed liveweight, was present in nea3 and SE pastures at 0.32 and 0.16 ppm. Staggers scoring at the onset of symptoms after 10 weeks of grazing revealed mild staggers (score <2) in SE that persisted until the experiment ended at 12 weeks. The model analysis showed that any mixture containing at least 60% nea3 and up to 40% nea12 and/or SE would result in no staggers (score 0). Alkaloids associated with staggers were in lower concentrations compared to the summer test: 0.8 ppm of epoxy-janthitrem I was present in nea12 pastures while lolitrem B, paxilline, and Terpendole C were present in SE pastures at 1, 0.1, and 0.3 ppm. The third experimental run tested the assumption that endophyte strain proportions in the diet were equal to the sown proportions. Plot fences within replicates were removed, 51–56 hoggets were allocated to each replicate (40.9–44.9 hoggets/ha), and sward height decrease was measured 15 times between 15 February and 16 March 2021. Herbage mass, ME, and CP values at the beginning of grazing were circa 1400 kg DM/ha, 11.5 MJ/kg DM, and 11%. Analysis of variance showed no differences (P>0.05) in sward height decrease between sown treatments, including nil, over the whole grazing period. Mixture models of each measurement date and the average of all dates only showed differences (P<0.05) between linear terms (monocultures) on day 2 and further analysis confirmed the sward height decrease of SE was greater than nea12 (P<0.05), but not nea3. Quadratic terms (binary mixtures) were not different on any date. The mixture model analysis for the whole period predicted that a mixture containing 39% nea3 and 61% SE would maximise sward height decline despite lolitrem B concentrations of SE pastures being sufficient to cause ryegrass staggers (1.4 ppm) and ergovaline levels in nea3 pastures of 0.37 ppm. The lack of deterrence to these alkaloids indicates that animals were unable to differentiate between endophyte strains. The fourth experimental run was a repeat liveweight gain test followed by a heat stress study from October to December 2021. Pasture conditions were similar to the previous liveweight gain test at the start of grazing (ca. 2400 kg DM/ha, 12 MJ ME/kg DM, 15% CP). The same number of hoggets were used as in the previous liveweight gain study, but a higher starting liveweight and greater pre- grazing pasture mass resulted in greater liveweight gain across mixtures in the first and second 4 weeks (397 and 67 g/day) compared to the previous spring. The model analysis predicted an optimum mixture containing 16% nea3, 65% nea12, and 20% SE would result in maximum liveweight gains of 402 and 85 g/day in the first and second 4 weeks of the test. Data loggers attached to controlled internal drug release (CIDR) devices recorded vaginal temperatures in selected mixtures (nea3, nea12, nea3–nea12, and nil) during the final 8 days of the 8-week grazing period. Average temperature for the three mixtures was 39.07°C compared to 38.96°C in the nil endophyte control. Hoggets grazing nea12 had the lowest temperature of the three mixtures (38.94°C; P<0.05). Consequently, the mixture model predicted the optimum mixture would only contain nea12. Ergovaline concentrations were 0.7 and 0.5 ppm in nea3 and SE. An endophyte diversity model that included ryegrass staggers and liveweight gain responses from experimental runs 1, 2, and 4 as multivariates, predicted a mixture containing 77% nea12 and 23% nea3 would give the best overall combination of responses. Although temperature was not included in the model, the vaginal temperature response of this optimal mixture was predicted to be 39.02°C, just 0.06°C higher than the nil endophyte control. This thesis showed that endophyte mixtures can improve the health of grazing sheep and provides the industry with a new option for mitigating health issues associated with endophyte without searching for novel strains. Such mixtures would be best suited to scenarios where insect pest pressure requires the use of endophyte strains that can increase the risk of ryegrass staggers and/or suppressed liveweight gain. The endophyte diversity modelling approach can predict responses to sown strain proportions beyond those included in the experiment, reducing the number of animal entries required for testing.Item Restricted Peri-urban landscapes and the potential of integrated foodscapes to support healthy cities: An Aotearoa New Zealand case study(Taylor and Francis Group, 2024)Aotearoa New Zealand is experiencing unprecedented competition in land use priorities on the edges of its cities and settlements–referred to as the peri-urban zone. Housing and food production compete with one another in a legislative planning context that supports a dichotomy of urban or rural land use. Food production is being driven further away from urban settlements, where 85% of New Zealanders live, as demand for housing increases, and land is re-zoned from rural to urban. Consequently, cities and settlements within Aotearoa New Zealand are increasingly seen to be spatially disconnected from their productive hinterlands. The resulting land use polarity occurring in the peri-urban zone is problematic for local food production, driving issues of agricultural land fragmentation, the loss of highly productive soils, ‘reverse sensitivity’, and impacts on human health and wellbeing. Engaging with both residents and food producers who reside and work within the peri-urban zone, this research applies a ‘design thinking’ methodology to the case study site of Ōtautahi Christchurch, exploring the question, ‘how can food production and housing best co-exist at the edges of Aotearoa New Zealand’s cities and settlements?’ to support human health and wellbeing outcomes. This paper presents five participant-driven future land use scenarios, which were developed based on survey responses collected from both peri-urban residents and food producers. The land use scenarios were then tested in a workshop setting with both groups assessing the potential of each scenario to address the land use conundrum that Aotearoa New Zealand peri-urban areas are currently facing, ultimately identifying land use strategies for healthier city areas that are designed for both housing and local food production.Publication Open Access The wellbeing experience within a New Zealand township. New Zealand Treasury’s Living Standards Framework in a hyper-local context : A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Applied Science at Lincoln University(Lincoln University, 2023)The New Zealand Treasury published ‘Te Tai Waiora’, its first wellbeing report in November 2022. The report presents data on how wellbeing has changed, how wellbeing is distributed and the sustainability of wellbeing in Aotearoa New Zealand. The data collected are analysed using the Living Standards Framework, which provides New Zealand Treasury with a systematic approach to offer policy advice and identify the implications of policy, based on a range of evidence gathered over time. This research tests the Treasury’s Living Standards Framework at a hyper-local scale (focusing on matters within a small community or specific geographic location), to understand the extent to which a central government approach to measuring wellbeing is appropriate at a local scale. This study found that indicators that provide data for analysis require context and are most relevant when applied ‘at scale’ to identify the wellbeing experience of individuals and communities. Using a mixed methods approach, the data from the quantitative research showed individuals are significantly more satisfied with various aspects of wellbeing at a local scale than at a national scale. These aspects include the natural environment, safety, housing affordability and political voice. In the qualitative data, it was found that, through a series of processes an individual generates their own wellbeing depending upon capabilities, financial security, locality and employment mobility opportunities. Individuals improved their wellbeing by making deliberate choices within the context of those capabilities. Home ownership was associated with employment mobility and individuals made trade-offs between dimensions of wellbeing as a function of personal value. Both research methods revealed that ‘local matters.’ The findings from this study will contribute to the growing literature on wellbeing. This thesis demonstrates that measuring the wellbeing experience of a small community in a specific geographic location can result in significant differences in wellbeing experiences between the national and local scale. Therefore, adopting an ‘at scale’ approach is more appropriate for policy development if central government is concerned with the wellbeing of all New Zealanders, irrespective of their locality.Item Open Access A new approach to understanding involvement: linking involvement to the memorability of experience(Springer Nature, 2024)Based on the involvement literature, the current research redefines the involvement theory and proposes a new form of involvement, namely situated involvement. The research, then, develops a scale to measure this involvement employing a mixed methods procedure. Afterward, the relationships between enduring, response, and situated involvements as well as the memorability of experience are investigated using structural equation modeling (SEM). The results from a survey of 317 tourists in Queenstown, New Zealand show that the memorability of experience is only impacted by situated involvement, the type of involvement which occurs during an experience. Enduring and response involvements are found to influence situated involvement, and enduring involvement predicts response involvement.
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