Permalink for this collection
The Department of Agricultural Sciences consists of animal science, plant science and farm management and agribusiness staff members.
The range of research conducted is quite extensive including: conversion of forests into pasture, alternative dryland pasture species, grain legume agronomy, sustainability in farming systems, nitrogen fixation and nitrogen cycling, shelter on dairy farms, economic viability of NZ farming systems, animal nutrition, immunology etc.
Browse
Recent Submissions
Publication Embargo Reducing nitrogen loss from cow urine patches: Strategies for pasture-based dairy systems : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University(Lincoln University, 2024) Kok, Jacobus ChristiaanIn dairy grazing systems, intensive farming practices with high nutrient inputs contribute to environmental pollution with nitrogen (N) loss from farmland, a key contributor to water quality degradation. The New Zealand dairy industry aims to reduce N leaching by 40-60% by 2030. Achieving this target may require transitioning from moderate to lower input systems and implementing mitigation strategies focused on managing high N sources, such as cow urine patches, to improve N use efficiency and reduce leaching risk. While cow urine patches present a primary source of N loss from pasture-based dairy farms, there is limited information on how the relationship between urine volume per urination event and urine patch area affect the N leaching risk. The aim of the thesis is to investigate this relationship and how grazing management strategies influence urine N load and plant N uptake following a regrowth period to mitigate N leaching risk. Additionally, it aims to develop a tool for predicting the impact of management strategies on N loss from urine patches. A key finding of the literature review was that successful N mitigation requires tactical and operational knowledge of implementing mitigation strategies, which has slowed adoption due to uncertainty in implementation. Additionally, the review also identified mitigations centred around the transfer of N, specifically relating to the urine patch, urine N load, or plant N uptake, to improve N use efficiency within a farm system. The review identified a lack of decision support tools for farmers to tailor N mitigations to individual circumstances. One finding was the opportunity to provide tactical and operational tools, such as a urine patch model, to understand urine distribution variation and develop management strategies that target urine and urine patch characteristics to reduce leaching risk. Using a modelling approach (Chapter 3), the aim was to determine if reducing N input alone could achieve the required N leaching reduction with minimal impact on farm operating profit, or if additional mitigation practices targeting N transfer from high N sources, such as cow urine patches, are needed to improve N use efficiency and reduce the risk of leaching. A two-year dairy farmlet study was conducted comparing two farm systems: moderate stocking rate (MSR, 3.9 cows/ha); and lower stocking rate (LSR, 2.9 cows/ha); with a benchmark, high-performing commercial demonstration farm (Lincoln University Dairy Farm [LUDF]; 3.4 cows/ha). Milk yield, pasture production, and quality data were collected, and modelled in FARMAX and OverseerFM to estimate the financial and environmental performance of each farm system. The LSR system produced the best environmental outcome across the two years (2018/19 and 2019/20), leaching an estimated 31% less N compared with MSR and LUDF, but at the cost of profitability. The average, annual milk solid production per ha was 28% less for LSR relative to MSR and LUDF. Correspondingly, the average annual operating profit per ha was 35% less for LSR compared with LUDF. A low N input system reduces production and operating profit to the extent that these mitigation strategies may not be adopted. Therefore, the next step was to target sources of high N input, such as cow urine patch areas, and improve N use efficiency from these areas to reduce the risk of leaching. In Chapter 4, we investigated the effects of grazed pasture canopy characteristics (using plant species and height) on urine patch area. The experiment was conducted during autumn in Canterbury, New Zealand. Warm water was used to simulate urine events, ranging in volume from 1 to 8 L, onto either partially (Lenient, 6-15 cm) or fully (Hard, <6 cm) grazed perennial ryegrass and white clover or pure plantain pastures. A thermal digital camera and imaging software were used to calculate the wetted area of each urine event. When a mid-range volume (4 L) was poured onto lenient grazed pastures, plantain had a greater wetted area than perennial ryegrass/white clover pasture (0.30 m2 ± 0.11 m2 and 0.16 m2 ± 0.08 m2, respectively; mean ± standard deviation). However, the wetted area was similar for plantain and perennial ryegrass/white clover pasture under hard grazing (0.36 m2 ± 0.16 m2 and 0.31 m2 ± 0.13 m2, respectively). Irrespective of pasture treatments and grazing intensity, the relationship between water volume and wetted area was curvilinear, with no significant increase in wetted area for simulated urine events greater than 4 L. Our results indicated that both pasture treatments and grazing intensity (i.e., residual pasture canopy) affect urine patch area, which could have potential implications for the urine N load per urine patch. A limitation of this study was that sward surface height was measured at the paddock level rather than for each urine event simulated. The first field experiment (Chapters 5 and 6) was split into two chapters to evaluate two objectives. The first objective was to investigate the effect of pre-graze pasture mass and time of pasture allocation, on total soil N levels from urine patches and subsequent N recovery from pasture following a regrowth period. The experimental design was a 2 x 2 x 2 factorial arrangement of treatments replicated twice within two experimental runs. The first factor corresponded to two levels of pasture mass using moderate to high mass (2226 or 2662 kg DM/ha respectively) to create lower herbage crude protein content in the high mass treatment. The second factor corresponded to time of allocation of pasture using morning or afternoon allocation. The third factor corresponded to time of urine deposition using anticipated peak (dawn) vs nadir (mid-morning) urinary N concentration and urine N load. A two-way interaction indicated larger urine patch areas for moderate mass at peak times (P < 0.05). As well as a three-way interaction which showed that moderate mass allocated in the afternoon resulted in larger urine patch areas (P < 0.05). Total soil N content was 6% higher (P < 0.05) for moderate mass but did not differ (P > 0.05) between peak and nadir times. High mass treatments showed better regrowth in both urine and non-urine patches. For non-urine patches, the herbage N yield was 18% lower for the moderate compared to the high mass pastures (P < 0.05). From this, we concluded that managing pasture mass can influence pasture recovery and nitrogen utilisation, with potential implications for reducing N leaching risk from dairy farms. Chapter 6 aimed to investigate the relationship between volume per urination, urine patch area, and compressed pasture height. The objective of this chapter was to understand if pasture management practices can affect urine patch area and subsequent urine N load. Cows were fitted with acoustic urine sensors (AgResearch, New Zealand) on their hind legs. The sensors captured the timing, duration, volume per urination, and frequency of urination. Thermal digital imaging with an automated algorithm (AgResearch) was used to estimate urine patch area. Our findings revealed that compressed pasture height did not affect the urine volume and patch area relationship. The relationship was also weaker compared to the findings in Chapter 4. The results showed the importance of accurate urine volume measurement and the impact that measurement errors with different methodologies could have on the relationship with urine patch area. Further research with accurate measurements of volume per urination and corresponding patch area is needed to develop tools to model urine and urine patch characteristics and N leaching risk accurately before they can inform management strategies. The second field experiment (Chapter 7) was carried out to collect additional data on the urine volume and patch area relationship. This study investigated the impact of pasture treatments and height on this relationship through simulated urination events. Conducted at Lincoln University Research Dairy Farm, the experiment utilised a 2 x 8 factorial design, comparing perennial ryegrass-white clover pasture with Italian ryegrass-plantain-red and white clover pasture across eight volume treatments (1-8 L). The study found no significant difference in urine patch area between pasture treatments. A curvilinear relationship between urine volume and patch area was identified (similar to that in Chapter 4), with a quadratic model (Urine patch area = 0.129 + 0.056v – 0.003v²) explaining 54.8% of the variance. Additionally, sward surface height significantly influenced urine patch area, with taller pastures reducing urine patch area, especially at higher urine volumes. This interaction was modelled (Urine patch area = 0.1259 + 0.09278v – 0.004742v² – 0.002363vh + 0.0001293v²h), explaining 70% of the variance. In summary, effective strategies must combine reduced N inputs with mitigation practices targeting N transfer from high N sources, such as cow urine patches, to improve N use efficiency and reduce leaching risk. This thesis has shown that altering pasture mass or the timing of pasture allocation does not significantly influence urine patch area; instead, it was primarily affected by the time of urine deposition. Additionally, these grazing management practices do not enhance plant N uptake from urine patches. Management practices aimed at reducing urine N load at peak times might be more effective at reducing N leaching risk than grazing management. However, grazing management can increase N transfer during the regrowth phase from small urine events. By managing sward surface height when smaller urine events fall within the linear part of the volume and patch area relationship, the urine patch area can be increased at the time of deposition, improving urine N load distribution and plant N uptake. Ultimately, the urine patch model indicated that reducing daily N intake and increasing daily urine volume throughout the year can reduce N leaching by up to 14.5%.Publication Open Access The abundance, activity, and community composition of comammox Nitrospira and canonical ammonia oxidisers in New Zealand soils : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University(Lincoln University, 2024) Chisholm, ChrisNitrification, the microbial oxidation of ammonia (NH3) via nitrite (NO2-) to nitrate (NO3-) is an important process in terrestrial ecosystems, as it contributes to the production of two environmentally significant products, nitrous oxide (N2O), and nitrate. Traditionally, nitrification was thought to be a two-step process, where ammonia is first converted to nitrite by ammonia-oxidising bacteria (AOB) before nitrite oxidising bacteria (NOB) complete the oxidation to nitrate. Later, it was discovered that a group of archaea (ammonia oxidising archaea, AOA) could also undertake ammonia oxidation, typically in oligotrophic/extreme conditions such as low ammonia availability and pH. The separation of nitrification into two steps involving different microorganisms has puzzled scientists as a single organism completing both steps of nitrification was theoretically assumed to be more efficient. The presence of complete ammonia oxidisers (comammox) was later confirmed by cultivating them from an aquaculture system and a core from a deep-sea oil well. It was found that comammox belongs to lineage II of the genus Nitrospira, a group of bacteria traditionally thought to be responsible for nitrite oxidation. Comammox Nitrospira and canonical Nitrospira can be distinguished by the presence of the ammonia monooxygenase gene (AMO). Furthermore, comammox Nitrospira can be separated into clade A and clade B based on the phylogeny of this gene. Clade A can also be further divided into sub-clades A.1, A.2.1, A2.2, and A.3. Since its initial discovery, comammox Nitrospira has been found in a variety of terrestrial ecosystems. Typically, studies have shown that clade B are more abundant in forest and paddy soils, whilst clade A.2 may prefer agricultural soils. Clade A.1 is seen to be the dominant cluster in natural and artificial aquatic ecosystems such as freshwater wells and wastewater treatment plants. However, the presence and distribution of comammox Nitrospira, relative to canonical ammonia oxidisers, in different soils and relationships with soil and environmental conditions are not fully understood. The research described in this Thesis was designed to fill this knowledge gap and improve our understanding of comammox Nitrospira and canonical ammonia oxidisers. Experiment 1 determined the abundance and community composition of comammox Nitrospira throughout New Zealand Dairy farms and quantified the abundance and community composition of comammox Nitrospira in New Zealand under various land uses. It was concluded that comammox Nitrospira are ubiquitous throughout New Zealand soils. Comammox Nitrospira amoA abundance shared a strong positive and strong negative correlation with soil moisture and pH, respectively. Interestingly, the sequencing analysis determined that the comammox Nitrospira community solely consisted of clade B. Two experiments were devised to investigate these correlations, with respect to canonical ammonia oxidisers. Experiment 2 explored the effect of soil pH, with N inputs, on comammox Nitrospira abundance and community composition in New Zealand dairy pasture soils. Comammox Nitrospira preferred the natural (6.1-6.2) soil pH with no nitrogen amendment. Comparatively, the AOB community (dominated by Nitrosospira) responded positively to soil pH and nitrogen input. This may be due to the difference in ammonia availability. Estimated ammonia availability in the synthetic urine treatments (equivalent to 700 kg N ha-1, N700) accurately predicted the AOB amoA gene abundance. Interestingly, the AOA communities (which were predominantly made up of Thaumarchaeota group I.1b clade E) seemed to prefer the natural and high pH soils over the low pH. This may be due to the lineage of AOA present. AOA did not respond to the application of nitrogen. Experiment 3 investigated the effect of soil moisture and temperature on comammox Nitrospira abundance, transcriptional activity, and community composition, relative to canonical ammonia oxidisers. AOB was the dominant nitrifier in the synthetic urine treated soil regardless of temperature or moisture. Peak AOB amoA transcript abundance was positively correlated with estimated soil ammonia availability. While the nitrification rate and changes in AOB amoA gene abundance followed a similar relationship. Ammonia oxidising archaea were strongly influenced by soil temperature. At 20 °C, AOA amoA peak transcript abundance averaged over 1 order of magnitude higher than at 8 °C. A member of the AOA community associated with the Nitrosocosmicus subclade was positively correlated with ammonium and estimated soil ammonia concentrations. The presence and relative increase of Nitrosocosmicus AOA in a high nitrogen environment poses an interesting contrast to the current scientific opinion. Contrary to Experiment 1, the abundance of comammox Nitrospira amoA was not positively correlated with soil moisture. This suggests that the association is more complex than previously thought. Further research is required to determine the drivers of comammox Nitrospira abundance in a high moisture environment. Overall, the results of this thesis indicate that in New Zealand, AOB are the dominant ammonia oxidiser in a nitrogen-rich environment, such as a dairy farm soil. While the majority of the AOA community prefer a high temperature, low nitrogen environment. However, Nitrosocosmicus-like AOA may respond positively to nitrogen amendment, which challenges our current understanding of terrestrial AOA. Comammox Nitrospira may prefer a slightly acidic, oligotrophic soil environment and do not respond to temperature change. However, they may be the main ammonia oxidiser in some high moisture environments, potentially due to biotic interactions with plants or microbes.Item Open Access Can additives or controlled release coating improve the nitrogen use efficiency of urea fertiliser?(New Zealand Grassland Association, 2024) Bryant, Racheal; Greig, JL; Mangwe, MA plot trial was undertaken to determine whether tactical use of nitrogen (N) fertiliser, applied with or without coating or additive, improved herbage yield and N use efficiency. A randomised complete block design was used to compare no fertiliser (CON), frequent low rates of urea (FL), infrequent moderate rates of urea (IM), IM with controlled release (IM+CR), IM with Progibb (IM+PG), IM with AgriSea (IM+AS), or IM with N-Boost (IM+NB) on irrigated, grazed perennial ryegrass and white clover dairy pastures in Canterbury. The total annual N applied in all fertilised treatments was 190 kg N/ha. The use of fertiliser increased annual herbage yield (16.9 vs 14.5±0.44 t DM/ha/y; P<0.05). Combining urea with a coating or additive altered the distribution of pasture growth but did not affect net annual production or herbage quality. Due to the lack of response and greater application costs with liquid versus granule products, these results highlight the need to consider expected responses to different fertiliser regimes when adopting practices to achieve economic benefits and N efficiency.Item Open Access Forage lucerne for grazing dairy cows: Effects on milk yield, milk urea and fatty acid composition(CSIRO Publishing, 2024) Mangwe, MC; Bryant, Racheal; Beckett, P; Tey, L; Curtis, J; Burgess, R; Al-Marashdeh, Omar; Eastwood, CallumContext. The value of milk components is increasingly recognised for human health benefits (e.g. omega-3 fatty acids, FA), or indicators of nutrient-use efficiency for both animal and environmental benefits (e.g. milk urea, MU). Aims. The study explored whether inclusion of lucerne (Medicago sativa L.) in a perennial ryegrass and white clover (Lolium perenne L. and Trifolium repens L, PRW)-based diet affects milk production, MU concentration, and milk FA composition of dairy cows during mid-lactation. Methods. Thirty-two cows, balanced for milk production (26.1 ± 3.03 kg/cow), MU (16.6 ± 2.84 mg/dL), and days in milk (94 ± 7 days), were evenly allocated into eight groups of four. Groups were then randomly assigned one of two dietary treatments, namely, PRW only (control), and PRW plus lucerne (lucerne). During an 8-day adaptation, control cows were fed a fresh allocation after each milking at 08:30 hours and 16:00 hours to provide 25 kg/cow.day DM of fresh PRW herbage above a target post-grazing height of 4.5 cm height. Cows on lucerne were allocated 10 kg DM of fresh lucerne at 08:30 hours, and 15 kg DM of fresh PRW at 16:00 hours. Apparent nutrient intakes and milk composition were determined on Days 9 and 10 of the study. Key results. Diet treatment did not significantly alter DM or metabolisable energy intake, milk production, or milk fat and protein percentage. However, compared with control cows, nitrogen and linoleic acid (LA) intake increased, and soluble carbohydrate, neutral detergent fibre, and alpha linoleic acid (ALA) intake decreased for cows fed lucerne. Milk urea increased by 43% for lucerne compared with control cows (22.4 vs 15.7 ± 1.43 mg/dL, P < 0.001). Cows grazing lucerne produced milk with a higher concentration of LA and ALA than did the control cows. Increases in milk LA from grazing lucerne were congruent with improvement in intake of the FA from the diet, whereas increases in ALA occurred despite the corresponding lower dietary intake. Conclusion. Supplementing a pasture diet with lucerne increased MU and FA. Implications. Lucerne has the potential to enhance dietary protein supply during periods of deficiency and increase the supply of functional FA in the milk of grazing dairy cattle.Publication Open Access Nitrogen dynamics of autumn wheat (Triticum Aestivum L.) sown on two dates in Canterbury, New Zealand : A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agriculture Science at Lincoln University(Lincoln University, 2024) Moody, GeorgiaWheat (Triticum aestivum L.) is a major global crop. It contributes to ~ 20% of global protein intake and is also grown for animal feed. In 2023, 40500 ha of wheat were harvested in New Zealand. It is important to understand the factors that affect crop production to maximize yield. However, the effects of nitrogen (N) on vegetative and early reproductive growth of wheat in high yielding environments is relatively uncharacterized. This experiment quantified light interception, biomass accumulation and partitioning of ‘Kerrin’ autumn feed wheat grown at 0%, 50%, 100% and 150% of the N dose required for a grain yield of 18t/ha in Canterbury, New Zealand. There were two independent experiments, one sown on 20th March 2024 (SD1), and the other sown on 16th April 2024 (SD2). Light interception and ground cover were recorded weekly and biomass harvests occurred every three weeks or at the key Zadok’s stages of 25, 30 and 32, whichever occurred first. Total biomass production for SD1 differed among treatments in the second to last harvest at Z30 stem elongation. The 0% treatment produced 487 kg DM/ha less than the 50, 100 and 150% treatments. The 0% treatment accumulated biomass the slowest at 3.56 kg DM/°Cd. The 100% and 150% treatments showed the highest rate of accumulation at 4.41 kg DM/°Cd whilst the 50% treatment was similar to both the 0% and 100 and 150% treatments. Leaf area index (LAI) for SD1 differed among treatments at the final three harvests. The 150% treatment had the highest LAI of 4.18 at final harvest. 50% and 100% treatments were intermediary with an LAI of 3.97 whilst the 0% treatment had an LAI of 3.5. LAI accumulated at 5.22E⁻⁰³ LAI/°Cd in the 50, 100 and 150% treatments which was faster than the rate of LAI accumulation of 3.87E⁻⁰³ LAI/°Cd in the 0% treatment. SLA differed among treatments at the second to last harvest. 150 and 50% had the highest SLA at 214 cm²/g which was higher than the 0% and 100% treatments at 196 cm²/g. In SD1, the 50% and 150% treatments intercepted a total of 330 MJ PAR/mV at the final harvest. This was higher than the 304 MJ PAR/m² intercepted by the 0% N treatment. The 100% treatments intercepted 324 MJ PAR/m² which was similar to the other treatments. In SD2, there were no differences among treatments for total biomass at each harvest, leaf, stem and dead material at the final harvest or rate of biomass accumulation. The 150% and 0% treatments had a lower proportion of leaf (68%) and higher proportion of dead material (7%) at the final harvest when compared to the 50% and 100% treatments. There were no differences in final LAI, rate of LAI accumulation, SLA, total light interception, or radiation use efficiency (RUE) among treatments in SD2. Differences in biomass accumulation in SD1 were attributed to greater light interception driven by increases in LAI. In SD2, the demand for N was not present during early crop growth which explained no differences among treatments.Publication Restricted Autumn production and water use of caucasian and white clover pastures with or without ryegrass: A dissertation submitted in partial fulfillment of the requirements for the degree of Bachelor of Agricultural Science with Honours At Lincoln University New Zealand(Lincoln University, 2003) Beverland, Chris J.The autumn production and water use of Caucasian and white clover pastures with or without ryegrass were examined at Lincoln University from late summer to mid winter 2003. Dry matter (DM) production and botanical composition were measured from 18 January to 16 July and water use from 5 March until 22 July. Pasture species were analysed for foliar nutritive content. Irrigated swards produced 101 % more total DM (3290 kgDM/ha) than did unirrigated swards (1640 kgDM/ha) from 18 January to 16 July 2003. Dry matter production was greater in Caucasian clover (Trifolim ambiguum M. Bieb) and ryegrass (Lolium perenne L.) swards in late summer (1740 kgDM/ha) compared to white clover (T. repens L.) and ryegrass (1020 kgDM/ha). Swards of white clover and ryegrass had increased production in the winter period (910 kgDM/ha) over Caucasian clover with ryegrass (530 kgDM/ha). This was due to increased ryegrass growth in the white clover swards. No differences in yield between the pure clover species occurred during the experimental period. Caucasian clover with ryegrass had an increased legume proportion in both dryland (58 % ) and irrigated (70 % ) swards in late summer compared with white clover and ryegrass (33 and 28% ). Clover composition declined in both species to be below 10 % in July. Water content in dryland Caucasian clover swards (276 mm) was significantly less than dryland white clover swards (319 mm) to a soil depth of 1.5 m. Pure Caucasian clover had a greater water extraction depth of 1.55 m compared with 1.35 min pure white clover swards, this indicates a deeper root system of Caucasian clover. Nutritive analysis showed Caucasian clover had low sodium levels (0.04 % ) compared to white clover (0.24 %) and ryegrass (0.29 %). Caucasian clover has been shown to be more competitive and productive with ryegrass in the summer period compared with white clover. Low winter productivity of Caucasian clover results in reduced cool season production and Caucasian clover and ryegrass swards.Publication Restricted Yield of turnips and kale grown under drought conditions in the Canterbury high country: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Agricultural Science with Honours at Lincoln University(Lincoln University, 2007) Reynolds, Robert DouglasDry matter production of kale (Brassica oleracea) and turnips (Brassica campestris) was studied in the Lees Valley, Canterbury, during one cropping season. The rainfall over the summer period was very low, and so moisture stress had a large influence on dry matter yields. Peak yields were 3.6 and 6.2 t DM/ha for turnips and kale respectively. There was no significant effect of nitrogen or phosphate treatments on yield of turnips; however nitrogen significantly increased the leaf yield of kale at one harvest date by 42.7%. This was a nitrogen response of 72.3 kgDM/ha/kgN. Radiation interception changed over time due to changes in the leaf canopies caused by environmental factors. The drought combined with insect damage caused much leaf senescence at first, resulting in a low radiation interception. The leaf canopies redeveloped after autumn rain and so radiation interception increased, until winter frosts caused a decline in leaf dry matter. At all stages of growth kale intercepted more radiation than turnips. The yield changed over time according to pressures imposed on the crops by drought and frost. Turnip yield decreased by 32% between 28/02/07 and 08/05/07 due to drought. The yield then increased by 32% as it recovered in late autumn, but then decreased by 47% due to frost in winter. Kale yield continued to increase throughout the drought, but decreased by 32% in winter. The turnip population declined over time from 48 plants/m² on 21/03/07 to 28 plants/m² on 25/07 /07, due to drought and frost damage. The leaf to bulb ratio of turnips also declined significantly over time from a high of 1.81 on 21/03/07 to a low of 0.43 on 25/07/07. Drought decreased leaf dry matter and had a minimal effect on bulb weight, while frost reduced leaf dry matter more than it reduced bulb weight. Both drought and frost damage resulted in a decline in leaf to bulb ratio. In a dryland environment that is likely to encounter significant summer drought kale will probably deliver a greater dry matter yield than turnips. Nitrogen should be applied if the soil cannot provide enough N for the yield potential of the site.Publication Restricted Autumn water use and yield performance of caucasian and white clover in east coast pastures: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Horticultural Science with Honours(Lincoln University, 2004) McBeth, Sarah L.The production and water use of irrigated Caucasian clover and white clover pastures with or without ryegrass was studied at Lincoln University, Canterbury. The experimental period extended from late summer to early spring 2004. Irrigation did not affect the total dry matter yield of pastures from 1 March to 9 September, 2004. However, irrigated swards produced 115% more dry matter than dryland pastures from 1 March to 2 June. Caucasian clover (Trifolium abiguum M. Bieb.) yield during the summer (3060 kg DM/ha) was higher than the yield of white clover (Trifolium repens L.) (2390 kg DM/ha) and ryegrass (Lolium perenne L.) (2910 kg DM/ha). During the winter, white clover and ryegrass pastures produced 40% more dry matter from April to June than Caucasian clover combined with ryegrass. This increased production in white clover swards was due to the ryegrass producing 50% more yield in the white clover pastures than in the Caucasian clover and ryegrass pastures. In January Caucasian clover and ryegrass pastures were 25-43% clover compared to 5-15% in white clover and ryegrass pastures. The clover content declined in both white clover Caucasian clover pastures to less than 10% by June. Dryland white clover pastures contained more bare ground than dryland Caucasian clover pastures (30% and 20% respectively). Water use from March to September was higher in irrigated (205 mm) pastures compared to dryland pastures (110 mm). White clover used 35 mm more water than Caucasian clover over the same period. Caucasian clover extracted water from a greater depth than white clover (1.7 m and 1.5 m respectively). Less water in the soil profile beneath Caucasian clover pastures below 1.0 m suggested that Caucasian clover has the ability to extract more water from greater depths than white clover.Publication Restricted Dry matter production and water use of red clover, chicory and lucerne in irrigated and dryland conditions : A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agricultural Science with Honours at Lincoln University(Lincoln University, 1999) Brown, HamishThe climate in Canterbury is dominated by hot, dry North-west weather conditions during the summer. The New Zealand standard ryegrass/white clover pasture is unsuitable for high animal production in these conditions because it suffers from low production and persistence. There is a need for alternative species that can increase the productivity of dryland areas and improve the efficiency of water use. To address these problems an experiment was established at Lincoln University in 1996. Dry matter (DM) production and water use of three high quality deep rooted perennial species, red clover (Trifolium pratense L.), chicory (Cichorium intybus L.) and lucerne (Medicago sativa L.), were measured under dryland and irrigated situations. Results from the third year of the experiment are presented and compared with the previous seasons to determine the potential of these species for use in Canterbury. Measurements were made over seven rotations from the 16 August 1998 - 24 June 1999. Under dryland conditions lucerne had greater annual dry DM production (21 t ha⁻¹ ) than red clover (15 t ha⁻¹) and chicory (13 t ha⁻¹ ). All species used 500 mm of water through the season and extracted water to about 2 m depth, thus lucerne had the highest water use efficiency (WUE). Similar yields were obtained in irrigated treatments, but 670 mm of water was used. Consequently the WUE was lower in irrigated conditions compared with dryland for all species. Differences in DM production came from greater lucerne production in the first spring rotation and the last three autumn rotations. There was no difference in DM production between species during the middle three rotations in late spring and summer. Root diseases in red clover and chicory contributed to their reduced production at the end of the third year. From this it was concluded that lucerne had greater potential than red clover or chicory for use in dryland or irrigated conditions in Canterbury.Publication Restricted Dry matter accumulation of three cultivars of turnip (Brassica campestris L.) sown in Canterbury on five sowing dates: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Agricultural Science with Honours at Lincoln University(Lincoln University, 1997) Collie, B. N.Dry matter production of three cultivars of Brassica campestris L. (cv Appin, York Globe, and Green Globe) sown on five dates (28 January, 11 February, 26 February, 11 March, 27 March) was studied in the field during one cropping season. Sowing date had a large effect on maximum dry matter production, with yields of 1540 g DM m⁻² to 595 g OM m⁻² being recorded for plots sown on 28 January and 27 March respectively. Maximum yields of 1105, 1185, and 1327 g OM m⁻² were achieved by cultivars of Appin, York Globe, and Green Globe respectively. Dry matter accumulation was linearly related to intercepted PAR for all sowing dates. However, there was some variation in efficiencies of dry matter accumulation, with 11 February sown crops producing 3.29 g OM MJ PAR' intercepted, compared to 2.5, 2.3, and 1.6 g OM MJ PAR' for the 26 February, 11 March, and 27 March sown crops. There was no difference in efficiency of dry matter production between cultivars, at most sewings. However, Green Globe was more efficient at producing dry matter at the last sowing. Highest yielding crops also had the best WMAGR of about 21 gDMm⁻²d⁻¹. Time to canopy closure was faster for crops sown on 11 February, and 26 February than for the later sowing date of 11 March (58 DAS v's 82 DAS). Plots sown on the 27 March never achieved canopy closure. Reduced canopy development was shown to occur due to a reduced rate of leaf appearance and leaf expansion. Appearance rate differed over a 53% range for the four sowing dates tested, with new leaves appearing every 2.9 days (plants sown on 11 February), 3.6 days per leaf (sown 26 February), 4.7 days per leaf (sown 11 March) and 5.6 days per leaf (sown 27 March). Comparisons between sowing dates in thermal time showed no difference (p>0.05), with one leaf appearing every 40°C.d. Final leaf length was greatest in higher order leaves. Leaf 2 expanded to 35% of the total length achieved by leaf 6 from plants sown on 11 February. Varying temperatures caused large differences (p<0.05) in the duration (days) of expansion between sowing date, with plants sown on the 11 February requiring an additional 8 days for complete expansion of leaf 6. When expressed in thermal time above a base temperature (0°C), individual leaves showed no difference (p<0.05) in the duration of linear growth with leaf 2 requiring 323.8 °C.d for expansion verses 346. 7 of leaf 6. No difference was observed in growth rate between sowing dates for the expansion of leaf 2. The results are discussed in relation to the determination of phenological development by temperature and radiation, and their impact on the growth of turnips.Publication Restricted Early growth of chickpea (Cicer arientinum L.) under various environmental conditions: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Horticultural Science (Honours) at Lincoln University(Lincoln University, 1997) Foley, Lynette MaryThree experiments were conducted to examine the early growth and nodulation responses of Kabuli chickpea to: a) Low 'starter dose' nitrogen (0, 15, and 30 kgN/ha) under increasing water stressed conditions, with different inoculation methods (dipped roots, solution, solid peat) (trial 1); b) Increasing nitrate concentrations (0, 1, 2.5, 5 Mol NO₃- m⁻³) with different inoculation rates (0, 1x, 4x) under non-water-stressed conditions (trial 2); c) Applied nitrogen (0-90 kgN/ha) with increasing inoculation rates (field trial). Water stress had increasingly negative effects on all plant DW components, except for increasing root DW by 27%, 18 DAS. At final harvest (49 DAS), shoot, root, nodule, and DWs were reduced 65, 20, and 73% respectively. Root:shoot was consistently greater in stressed plants (70, 53, and 84%, at 18, 34 and 49 DAS). Interactions between nitrogen and irrigation (affecting plant and root DWs, 18 DAS) implied that reduced early growth due to mild water stress may be partially offset by nitrogen fertiliser through greater root (but not shoot) growth. However, at 34 DAS), water-stressed total plant DW did not respond to nitrogen, whereas total plant DWs of fully irrigated plants increased by =38% at both 15 and 30 kgN/ha. Inoculation method had little effect. Shoot DW's were increased with increasing nitrogen concentration (11 and 16 % at 15 and 30 kgN/ha, 49 DAS; 41, 85 and 148%, at 1, 2.5, and 5 Mol NO₃- m⁻³, 43 DAS). Rootshoot decreased with increasing nitrogen concentration at all harvests, except at 43 DAS.Item Open Access Light regulates secreted metabolite production and antagonistic activity in Trichoderma(Multidisciplinary Digital Publishing Institute (MDPI), 2025-01) Esquivel-Naranjo, Edgardo Ulises; Mancilla-Diaz, Hector; Marquez-Mazlin, Rudi; Alizadeh, Hossein; Kandula, Diwakar; Hampton, John; Mendoza-Mendoza, ArtemioSecondary metabolism is one of the main mechanisms Trichoderma uses to explore and colonize new niches, and 6-pentyl-α-pyrone (6-PP) is an important secondary metabolite in this process. This work focused on standardizing a method to investigate the production of 6-PP. Ethanol and ethyl acetate were both effective solvents for quantifying 6-PP in solution and had limited solubility in potato–dextrose–broth media. The 6-PP extraction using ethyl acetate provided a rapid and efficient process to recover this metabolite. The 6-PP was readily produced during the development of Trichoderma atroviride growing in the dark, but light suppressed its production. The 6-PP was purified, and its spectrum by nuclear magnetic resonance and mass spectroscopy was identical to that of commercial 6-PP. Light also induced or suppressed other unidentified metabolites in several other species of Trichoderma. The antagonistic activity of T. atroviride was influenced by light, as suppression of plant pathogens was greater in the dark. The secreted metabolite production on potato–dextrose–agar was differentially regulated by light, indicating that Trichoderma produced several metabolites with antagonistic activity against plant pathogens. Light has an important influence on the secondary metabolism and antagonistic activity of Trichoderma, and this trait is of key relevance for selecting antagonistic Trichoderma strains for plant protection.Item Open Access An economic model evaluating competitive wheat genotypes for weed suppression and yield in a wheat and canola rotation(Multidisciplinary Digital Publishing Institute (MDPI), 2025-01) Nordblom, Thomas L; Gurusinghe, Saliya; Hendriks, Pieter-Willem; Rebetzke, Greg J; Weston, Leslie ARecurrent selection for early vigour traits in wheat (Triticum aestivum L.) has provided an opportunity to generate competitive biotypes to suppress agronomically important weeds. Quantifying the potential benefits of competitive genotypes, including yield improvement and reduced frequency of herbicide application when incorporated into a long-term rotation, is vital to increase grower adoption. In this simple economic model, we evaluated a weed-suppressive early vigour genotype utilising on-farm experimental results and simulation analysis to predict gross margins for a seven-year wheat-canola rotation in southeastern Australia. The model applied a local weather sequence and predicted wheat production potential, costs and benefits over time. An early vigour wheat genotype was compared to commercial wheat cultivars for weed control, yield and actual production cost. With respect to weed control, three scenarios were evaluated in the model: standard herbicide use with a commercial cultivar (A), herbicide use reduced moderately by inclusion of an early vigour wheat genotype and elimination of the postharvest grass herbicide (B) or inclusion of an early vigour wheat genotype and withdrawal of both postharvest grass and broadleaf herbicides (C). Cost savings for the use of a competitive wheat genotype ranged from 12 AUD/ha in scenario B to 40 AUD/ha in scenario C, for a total saving of 52 AUD/ha. The model generated annual background gross margins, which varied from 300 AUD/ha to 1400 AUD/ha based on historical weather conditions, production costs and crop prices over the 30-year period from 1992 to 2021. The benefits of lower costs for each of the three scenarios are presented with rolling seven-year average wheat–canola rotation gross margins over the 30-year period. The limitations of this model for evaluation of weed suppression and cost benefits are discussed, as well as relative opportunities for adoption of early vigour traits in wheat.Item Open Access Impact of year and genotype on benzoxazinoids and their microbial metabolites in the rhizosphere of early-vigour wheat genotypes in Southern Australia(Multidisciplinary Digital Publishing Institute (MDPI), 2025-01) Weston, Paul A; Parvin, Shahnaj; Hendriks, Pieter-Willem; Gurusinghe, Saliya; Rebetzke, Greg J; Weston, Leslie AWheat (Triticum aestivum) is grown on more arable acreage than any other food crop and has been well documented to produce allelochemicals. Wheat allelochemicals include numerous benzoxazinoids and their microbially transformed metabolites that actively suppress growth of weed seedlings. Production and subsequent release of these metabolites by commercial wheat cultivars, however, has not yet been targeted by focussed breeding programmes seeking to develop more competitive crops. Recently, the Commonwealth Scientific and Industrial Organisation (CSIRO), through an extensive recurrent selection programme investment, released numerous early-vigour wheat genotypes for commercial use, but the physiological basis for their improved vigour is under investigation. In the current study, we evaluated several early-vigour genotypes alongside common commercial and heritage wheat cultivars to assess the impact of improved early vigour on the production and release of targeted benzoxazinoids by field-grown wheat roots over a two-year period. Using UPLC coupled with triple quadrupole mass spectrometry (LC-MS QQQ), we quantified common wheat benzoxazinoids and their microbially produced metabolites (aminophenoxazinones) in soil collected from the rhizosphere and rhizoplane of wheat plants over two growing seasons in the Riverina region of New South Wales, Australia. The benzoxazolinone MBOA and several aminophenoxazinones were readily detected in soil samples, but actual soil concentrations differed greatly between years and among genotypes. In contrast to 2019, the concentration of aminophenoxazinones in wheat rhizosphere soil was significantly elevated in 2020, a year receiving adequate rainfall for optimal wheat growth. Aminophenoxazinones were detected in the rhizosphere of early-vigour genotypes and also parental lines exhibiting weed suppression, suggesting that improved early vigour and subsequent weed competitiveness may be related to increased root exudation and production of microbial metabolites in addition to changes in canopy architecture or other root-related early-vigour traits. As previously reported, MBOA was detected frequently in both the rhizoplane and rhizosphere of wheat. Depending on the year and genotype, we also observed enhanced biotransformation of these metabolites to several microbially transformed aminophenoxazinones in the rhizosphere of many of the evaluated genotypes. We are now investigating the role of early-vigour traits, including early canopy closure and biomass accumulation upon improved competitive ability of wheat, which will eventually result in more cost-effective weed management.Publication Open Access Coopworth hogget and lamb liveweight gain on regenerative and conventional dryland pastures : A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agricultural Science (Honours) at Lincoln University(Lincoln University, 2024) Holt, BreannaRegenerative systems have been proposed as a potential greenhouse gas mitigation strategy for New Zealand agricultural systems. They focus on a holistic approach which encompasses, plant, animal, soil and community health. Regenerative agriculture principles claim to naturally increase carbon storage, soil fertility and biodiversity while producing the equivalent harvestable product of conventional systems. This dissertation reports on the liveweight gain of Coopworth hoggets and lambs grazing conventional and regenerative dryland pastures under high (20 mg/kg) and low (10 mg/kg) Olsen P giving four treatment groups: high conventional (HC), low conventional (LC), high regenerative (HR) and low regenerative (LR). The research period was within the establishment phase of the ongoing regenerative agriculture dryland experiment at Lincoln University. Four 2-ha farmlets, of 20 paddocks each, were established between 10 December 2021 and 16 March 2023. Grazing management and pasture species were the main attributes under investigation. Animals under regenerative management grazed multi-species forages (>8 species), under high intensity, short duration, with high residual, rotational grazing. Whereas, conventional grazing management was rotational, with duration and rotation length based on pasture cover. Differences in animal liveweight gain (LWG), were explained by the pasture production and quality for each of the two Coopworth flocks (ewe hoggets and then ewe lambs) which grazed between 11 September 2022 and 3 August 2023. The first ewe hogget flock grazed between 11 September 2022 and 3 March 2023. These animals were replaced with new season ewe lambs from 3 March to 3 August 2023. Conventional treatments produced the greatest LWG. The Coopworth hoggets and lambs grazed on conventional pastures accumulated 42 to 60 (hoggets) kg LWG/ha and 15 to 28 (lambs) kg LWG/ha more than those on RA treatments. This difference was attributed to greater crude protein content (20% CA, compared with 15% RA) and lower neutral detergent fibre (40% CA, compared with 46% RA) due to increased legume in the lucerne-based conventional diet. This meant animals met their daily intake requirements sooner which enabled increased total intake, due to increased rate of rumination. Pasture production and quality were affected by water stress in this summer dry rainfed environment. Pastures were shown to be water stressed from 13 November 2022, when 157 mm actual soil moisture deficit was reached, until March 2023. During autumn and winter 2023 pasture grew based only on rainfall. Soil water had not recharged until July 2023. There was no effect on pasture quality or legume production during the experimental period due to Olsen P treatments, however, further research over time is required to confirm these results.Publication Restricted Growth and nodulation of autumn sown chickpea (Cicer arietinum L.) as affected by additional nitrogen: A dissertation submitted in partial fulfillment of the requirement for the degree of Bachelor of Horticultural Science (Honours) at Lincoln University(Lincoln University, 1992) Stokes, Jo-Anne RuthTwo glasshouse experiments and a field experiment were carried out to examine the growth and nodulation response of inoculated Kabuli and Desi chickpea to application of nitrogen. In the glasshouse experiments, a range of nitrogen levels were applied (0, 12.5, 25, 37.5, 50 and 100 mol N m⁻³). Leaf area and shoot dry matter production for both chickpea types, and nodule dry weight for Kabuli chickpea were measured. In the field experiment, autumn sown Kabuli and Desi chickpea shoot and nodule dry matter were measured to determine the response of chickpea to application of 100 kg N ha⁻¹. Application of nitrogen increased leaf area and shoot dry weight in the first glasshouse experiment by 36 and 42% respectively but had little effect in the second. Nodule dry weight of Kabuli chickpea decreased with increased application of nitrogen in both experiments by 42 % and 45 % respectively. In the field, application of nitrogen had little effect on shoot or nodule dry weight. It was concluded that autumn sown chickpea are able to survive a Canterbury winter, but survival of Rhizobium bacterium may be poor. Application of nitrogen may increase shoot growth in the longer term but has little effect initially. Nodule dry weight decreases with increased applied nitrogen. If nitrogen fertilizer is to be applied, spring and summer application is recommended.Publication Restricted A study of factors influencing the solids not fat of milk with particular reference to the effect of feeds having oestrogenic activity : A thesis submitted in partial fulfilment of the requirements for the degree of Master of Agricultural Science(Lincoln College, University of Canterbury, 1952) Vial, Vivian. EdwardThe value of milk in the National dietary cannot be too strongly emphasized; no single food is nutritionally complete but milk must be regarded as a product which most nearly attains the ideal. There is a growing public awareness of the role of milk as a "protective'• foodstuff and as a supplement to the normal carbohydrate-rich diet of the average New Zealand household. In the past, milk quality has been synonomous with keeping quality and the bacteriological status of the milk passed on to the consumer, but more recently- through the medium of the press, Government departments and local bodies, the concept of nutritive status has started to assume the importance it warrants; even so, to the public in general, the value of the various milk components is only vaguely appreciated; New Zealand's liquid milk supply has been the Cinderella of the Dairy Industry for too many years since statistically it accounts for only 9% of the Dominion's total butterfat production.Publication Restricted Some effects of vesicular-arbuscular mycorrhizas on the nitrogen nutrition of perennial ryegrass (Lolium perenne L.): A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agricultural Science (Honours) in the University of Canterbury(Lincoln College, University of Canterbury, 1978) Buwalda, J. G.Vesicular-arbuscular {VA) mycorrhizas are widespread in nature, occurring on more plant species than any other form of mycorrhiza {Gerdeman, 1975). Their importance in plant nutrition, particularly phosphorus nutrition, is now well established (Mossa, 1973a), and VA mycorrhizas may significantly influence the growth and composition of natural communities in soils of low available phosphorus. Vesicular-arbuscu:lar mycorrhizas have also been found to significantly influence the growth of agricultural crop (Khan, 1975b) and pasture (Crush, 1976) plants~ Different species of mycorrhizal fungi enhance the growth and phosphorus nutrition of the hos·t to varying extents, and inoculation of plants with more efficient species of mycorrhizal fungi would therefore appear profitable.Item Open Access Validation of a remote sampling sensor for measuring urine volume and nitrogen concentration in grazing dairy cattle(Multidisciplinary Digital Publishing Institute (MDPI), 2024-10) Mangwe, MC; Beale, N; Beckett, P; Tey, L; Curtis, J; Burgess, R; Bryant, RachealThe purpose of this research was to validate a urine sensor (Lincoln University PEETER V2.0, Canterbury, New Zealand) that records the time and volume of urination events for dairy cows in addition to collecting a proportional urine sample from all urination events. Sixteen multiparous Holstein × Jersey mid-lactating cows (101 ± 5 days in milk, 498 ± 24.2 kg body weight, 26.2 ± 3.07 kg/d milk yield; mean ± standard deviation) were allocated herbage diets ranging in protein and sodium content to generate a range of urine volumes and urine nitrogen (UN) concentrations. Total collection of individual urination events occurred during a 72-h measurement period where PEETER V2.0 sensors were attached to cows. A mixed model ANOVA using lme4 package (version 1.1-35.5) in R (version 4.3.3) were used to compare the means. The average urine event size was 2.65 ± 1.1 L for total collection by observers and 2.68 ± 1.1 L as recorded by the sensor (mean ± standard deviation; p = 0.730). The urine nitrogen concentration was 5.76 ± 1.2 g N/L for samples collected by observers and 5.85 ± 1.3 g N/L for the samples collected by the sensor (p = 0.583). The calculated UN excretion was 156 ± 45.1 g/day for direct measurements and 162 ± 40.0 g/day for the sensor (p = 0.539. Contrasts with simultaneously measured data were undertaken using Lin’s Concordance Correlation Coefficient (CCC) and a Pearson correlation coefficient (r). Correlations between the actual values and sensor values were strong, with little to moderate variability in the urine volume (CCC = 0.936, r = 0.937; n = 222), UN concentration (CCC = 0.840, r = 0.837, n = 48) and total UN excretion (CCC = 0.827, r = 0.836, n = 24). Considering the findings, the PEETER V2.0 urine sensor has the potential to reliably measure urine volumes and UN concentrations for estimations of the UN excretion of dairy cattle under grazing systems.Publication Open Access Behavioural traits to identify subclinical diseases of grazing ruminants : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University(Lincoln University, 2024) Fan, BowenAnimal welfare and wellbeing can be improved through the early detection and diagnosis of disease. Subclinical infections in particular can be difficult to determine, however, animals may demonstrate subtle changes in behaviour. These changes related to eating, ruminating, inactive behaviour and active behaviour can potentially be identified and measured through sensor technologies. This thesis composes of a series of studies designed to explore changes in behavioural patterns of grazing ruminants experimentally challenged with subclinical infections using commercially available accelerometers. The objective of the first trial (Chapter 3) was to investigate the changes in grazing, ruminating and activities of grazing dairy calves infected with the internal gastrointestinal nematodes Ostertagia ostertagi and Cooperia oncophora and determine the behavioural patterns after receiving an anthelmintic treatment, using neck mounted sensor collars. At Day -12 relative to an experimental infection, animals were dewormed and fitted with Allflex EveryCow collars which can identify mutually exclusive behaviours such as eating, ruminating, resting, walking, medium activity, high activity and behaviour related to heavy breathing. On Day 0, they were allocated into one of two treatments, viz, Infected, in which animals were orally dosed weekly for three weeks with a 1:1 mixture of 20,000 O. ostertagi and C. oncophora L3 larvae, or Control in which animals remained uninfected, and grazed a new pasture that had not previously been grazed. Animals were rotationally grazed as a mob with weekly shifts and each break back-fenced to reduce the risk of self-infection. On Day 49, to assess the behavioural response following anthelmintic treatment, half of calves in each treatment were orally administered with the Matrix Oral triple combination anthelmintic and continued to be monitored, using a 2 × 2 factorial experimental design, viz, Control without Drench (COD), Control with Drench (CD), Infected without Drench (IOD), Infected with Drench (ID). Results showed nematode challenge increased daily eating time (+14.8 minutes per day, mins/d, P = 0.007) and reduced daily ruminating time (-9.8 mins/d, P = 0.001) and daily mid-activity duration (-5.3 mins/d, P = 0.023) in grazing calves. After 49-day challenge of gastrointestinal nematode (GIN) infection, the mean faecal egg counts (FEC) of Infected and Control groups were 700 ± 181 and 33 ± 18 eggs/gram, respectively. Furthermore, there was a lack of a consistently high level of parasitism in the calves. To help determine if there was any potential for subtle changes in behaviour to be detected, three animals at the extremes of each of the initial intended treated groups, viz, animals in IOD and 3 animals in ID with the highest FEC and three calves in COD and four calves in CD with highest body weight gain were selected. Parasitism increased FEC and decreased daily live weight gain (643.7 g/day vs 790.6 g/day for parasitized animals and control animals respectively, P = 0.029) from Day 20 to Day 49. There were non-significant negative correlations between log10 (FEC+1) and behavioural measurements for daily eating duration (r = -0.085, P = 0.501), daily walking duration (r = -0.16, P = 0.191), daily mid-activity duration (r = -0.18, P = 0.155), daily high activity duration (r = -0.060, P = 0.636), and daily heavy breathing duration (r = -0.17, P = 0.174) with non-significant positive correlations for daily ruminating duration (r = 0.018, P = 0.889) and daily rest duration (r = 0.16, P = 0.197). In the parasitized animals with the high-level output of FEC, nematode infection significantly increased their mean daily eating duration (+34.6 mins/d, P = 0.020), compared with their uninfected counterparts, and had no effect on mean daily ruminating duration (-18.2 mins/d, P = 0.737), mean daily walking duration (-14.4 mins/d, P = 0.598), mean daily mid-activity duration (-10.3 mins/d, P = 0.498), mean daily high activity duration (-7.2 mins/d, P = 0.744). Moreover, nematode infection increased eating time during cooler periods of the day (+1.7 mins/h from 0400 to 0800 hours, +1.5 mins/h from 2000 to 2300 hours) and decreased in the early morning (-0.7 mins/h from 0000 to 0300 hours) and in the afternoon (-1.5 mins/h from 1300 to 1700 hours) (P < 0.001), and reduced the duration of mid-activity during most times of the day (-0.5 mins/h from 0000 to 0700 hours, -0.2 mins/h from 1100 to 1300 hours, -0.2 mins/h from 1500 to 2300 hours, and +0.2 mins/h from 0800 to 1000 hours, P = 0.007). In parasitized animals post anthelmintic drenching, heavy breathing duration was decreased (-0.1 mins/h) from 0200 to 0500 hours and then increased (P = 0.010) during most time of the day (from 0600 to 0900 hours, from 1100 to 1600 hours and from 2200 to 0100 hours) with fluctuations from 1700 to 2100 hours. In control animals post anthelmintic drenching, walking duration was reduced (P = 0.010) during early morning from 0100 to 0700 hours (-0.4 mins/h) and at dusk from 1700 to 1800 hours (-0.6 mins/h), and increased from 0800 to 1600 hours (+0.3 mins/h) and in the late evening from 1900 to 0000 hours (-0.2 mins/h), while heavy breathing duration was increased (P = 0.018) during most times of the day (+0.1 mins/h from 0500 to 0900 hours, +0.2 mins/h from 1100 to 0000 hours). Unfortunately due to an outbreak on Mycoplasma bovis on the research farm the first study was required to be terminated after only a short-time post-drenching. Due to biosecurity requirements continuing investigations in cattle was not an option and it was decided to instead use sheep as the species of choice for the remainder of the studies. A paucity of commercially available sensors for sheep meant that alternatives must be found and validated. Of these, the Cowmanager sensor tags were chosen due to their relative size and weight and possible suitability for a sheep ear. However, these tags had not previously been evaluated in sheep. The second trial (Chapter 4) was aimed to determine if the Cowmanager tags could provide an accurate and meaningful representation of the behaviour of sheep. In order to do this, a lipopolysaccharide (LPS) challenge model was used which provides a predictable and consistent short-term change in animal behaviour such as lethargy, and inappetence without long-term negative consequences. At recruitment (Day -10), twenty female Coopworth lambs of 8-10 months (mean live weight = 38.63 ± 2.04 kg) were weighed and fitted with CowManager SensOor ear tags which can identify mutually exclusive activities of five categories: eating, ruminating, inactive behaviour, active behaviour and highly active behaviour, and allocated within live weight strata to one of two treatments, respectively receiving 0 or 0.5 μg/kg body weight of endotoxin LPS with an experimental design of 2 × 2 Latin square. On Day 0, the lambs in the LPS group were intravenously injected with LPS contained in sterile saline, while the control lambs were intravenously injected with sterile saline solution. Seven lambs (four lambs in the LPS group and three control lambs) were randomly selected and individually marked for visual identification for verification of the behavioural changes. To validate the data between visual observation and sensor recordings, the behaviours of the seven lambs were visually observed and recorded every minute for 60 consecutive minutes for two hours between 0900 hours and 1600 hours within three days around the period of LPS infusion. A week after the first intravenous infusion of LPS, the two groups were swapped and intravenously administered with 0.5 or 0 μg/kg body weight of LPS, and the experimental procedure was repeated for the second period. The behaviours of the same seven lambs previously marked for visual identification was recorded via visual observation based on the same procedure to compare with sensor recordings. LPS infusion elevated rectal temperatures after 4 hours from 39.31℃ to 39.95℃, indicating successful establishment of an acute fever response for comparison between groups (P < 0.001). Results showed there was good agreement between visual observations and sensors for active and not active behaviour, but poor agreement with eating and ruminating time. For each of the five recorded behaviours, time spent eating, ruminating, not active, active and highly active, the accelerometers were able to detect an effect of LPS challenge. Compared with the control, LPS infusion decreased eating time (-6.7 mins/h, P < 0.001), active behaviour (-8.4 mins/h, P < 0.001) and highly active (-2.9 mins/h, P < 0.001) and rumination time (-1.4 mins/h, P = 0.075) and increased inactive behaviour (+16.0 mins/h, P < 0.001) in challenged lambs. This provided validation of the Cowmanager tags for use in sheep. Alkaloids produced by ryegrass endoyphytes are known to cause changes in animal behaviour, inducing heat stress and ryegrass staggers in severe cases. In Chapter 5, the potential for CowManager SensOor ear tags to categorize changes in eating, ruminating and other behavioural activities of grazing lambs exposed to endophyte-infected perennial ryegrass was evaluated. Thirty Coopworth lambs with a mean live weight (± SE) of 33.6 ± 0.46 kg were allocated randomly within live weight strata to either endophyte-free cultivars of ryegrass (Control) or wild type endophyte-infected cultivars of ryegrass pasture (Endophyte). Live weight change, behaviour and incidence of ryegrass staggers were monitored over a 2-month grazing period. Moderately severe staggers (score 4/5) occurred in 40% of lambs in the endophyte treatment with a mean staggers score of 2.33 ± 0.41 (P < 0.001) for the endophyte group at the end of trial. During the period of ryegrass staggers, compared with those grazing the control pasture, lambs in the endophyte group had had no significant difference in eating time (-36.0 mins/d, P = 0.516), time spent being active (+29.9 mins/day, P = 0.556) and being inactive duration (-43.7 mins/day, P = 0.114), but increased time spent ruminating (+40.2 mins/d, P = 0.051). When comparing lambs in the same group with stagger score 4 and those with staggers score 1 or 0 during staggers period, these behavioural differences were even more pronounced though non-significance was presented (-82.2 mins/d for eating, P = 0.073; -62.9 mins/d for being inactive, P = 0.221; +124.0 mins/d for being active, P < 0.001; +48.9 mins/d for ruminating, P = 0.015), indicating that it was not a reflection of the different swards or the physical characteristics. Changes in the pattern of behaviours during staggers period were also evident as reflected in a diurnal alteration of each activity over time of the day. The challenge of toxic alkaloids produced in endophyte-infected ryegrass led to more time eating during cooler period of the day (P < 0.001) and more time being active for compensation during day-time (P < 0.001) as well as more ruminating time during night-time (P < 0.001) and less time being inactive (P < 0.001) and highly active (P < 0.001), especially in the lambs with severe ryegrass staggers. The final trial then compared the effect of a chronic subclinical infection with gastrointestinal nematode parasites on sheep behaviours (Chapter 6). At start of this trial on Day 0, thirty-six Coopworth ram lambs at 8-10 months of age were weighed, fitted with CowManager SensOor ear tags, and randomly allocated within live weight to one of four experimental groups, non-parasite exposure groups (NP), NP1 (n = 9, 34.89 ± 3.93 kg,) and NP2 (n = 9, 34.56 ± 2.82 kg), oral administration of parasites (OP), OP1 (n = 9, 34.89 ± 3.00 kg) and OP2 (n = 9, 34.44 ± 2.94 kg) with a three-times weekly trickle infection for four weeks with the equivalent of 130 Teladorsagia (Ostertagia) circumcincta L3 larvae per kg live weight (LW) and 80 Trichostrongylus colubriformis L3 larvae per kg LW per day. After 4 weeks of infection, the NP1 group and OP1 group were orally administered once with an anthelmintic. Two weeks later, the NP2 group and OP2 group were orally treated once with the same anthelmintic. GIN infection resulted in a reduction in mean daily eating time (-91.7 mins/d, P = 0.001) and an increase in mean time spent being inactive (+88.4 mins/d, P = 0.001) and active (+7.4 mins/d, P = 0.017) with no differences in mean daily ruminating time (-15.5 mins/d, P = 0.395) and mean daily highly active duration (+12.7 mins/d, P = 0.400). Compared with the control, the animals challenged with nematode infection increased eating time during cooler period of the day (+1.5 mins/h from 2000 to 0200 hours) with less time spent eating during sunrise (-4.7 mins/h) and sunset (-1.7 mins/h) (P < 0.001). Further, compared with the control, the animals infected with nematode reduced daytime ruminating (-0.5 mins/h from 0600 to 1600 hours) and increased ruminating time at dusk (+0.5 mins/h from 1700 to 1900 hours) and in the evening (+0.8 mins/h from 2100 to 0000 hours) (P < 0.001). In addition, compared with the control, nematode infection increased inactive time of parasitized animals in the early morning/after sunset with a reduction during the late afternoon (-0.6 mins/h from 1400 to 1800 hours) and late evening (-1.1 mins/h from 2200 to 0100 hours) (P < 0.001), increased active duration in the early morning (+1.2 mins/h from 0400 to 0700 hours) with reductions in the late morning (-0.2 mins/h from 1000 to 1200 hours) and from late afternoon to evening (-0.3 mins/h from 1500 to 2200 hours) (P < 0.001), and increased highly active duration during most times of the day (+0.6 mins/h from 0300 to 1800 hours) with a decrease in the evening (-1.1 mins/h from 1900 to 0200 hours) (P < 0.001). Compared with the control animals, for the infected animals, anthelmintic drenching increased eating time during most of the daytime +1.6 mins/h with a decrease during cooler times of the day (-2.4 mins/h from 2000 to 0300 hours) (P < 0.001), increased night-time ruminating (+1.3 min/h from 2000 to 0200 hours) with an increase in the early morning (-1.1 mins/h from 0300 to 0800 hours) and in the afternoon (-1.0 mins/h from 1300 to 1800 hours) (P < 0.001), increased inactive duration in the morning (+0.9 mins/h from 0200 to 1000 hours) and in the afternoon (+1.3 mins/h from 1200 to 1700 hours) with a decrease in the early evening (P < 0.001), reduced active duration from 0300 to 0500 hours (-0.6 mins/h) and from 0700 to 1400 hours (-1.1 mins/h) with an increase from 1500 to 1800 hours (+0.9 mins/h) and from 2000 to 0200 hours (+0.9 mins/h) (P < 0.001), decreased highly active duration during most of the daytime (-1.1 mins/h from 1000 to 1800 hours) with an increase in the evening (+2.2 mins/h from 1900 to 0100 hours) (P < 0.001). In summary, the results from these trials demonstrate that altered behavioural patterns of grazing animals due to health challenges of diseases or toxins can be detected through commercially available sensor technologies. Acute health challenge in lambs can increase inactive duration and compensate to reduce eating duration, rumination duration, active duration and highly active duration in a short period, whereas chronic endophyte staggers challenge in lambs results in increased daily active duration and daily ruminating duration with a decrease in daily eating duration, daily inactive duration and daily highly active duration. Chronic subclinical parasitic challenge in dairy calves can induce an increase in daily eating duration and daily rest duration, and decrease daily durations of ruminating, walking, mid-activity, high-activity and heavy breathing. However, chronic subclinical nematode challenge in lambs can result in a decrease in daily durations of eating, ruminating and an increase in the daily durations of being inactive, active and highly active. The magnitude and duration of total daily behavioural changes varied under these health challenges. Moreover, both chronic subclinical GIN challenge and chronic challenge of toxic alkaloids in endophyte-infected ryegrass can increase eating time during cool periods of the day, decrease time spent being active during nighttime with an increase in the daytime in grazing lambs at pasture. However, chronic subclinical GIN challenge can increase inactive duration at sunrise and sunset and decrease daytime ruminating and increase ruminating duration in the evening, while chronic challenge of toxic alkaloids can increase ruminating duration with a reduction in inactive duration during most of the day. Consequently, behavioural changes detected by commercially available sensor technologies evaluated in these studies could be applied as a useful and potential tool to identify changes in behavioural patterns of each category under infection challenges of diseases or toxins, indicating animal health status and determining the need of treatments for individuals or a whole mob.