ItemEffects of forms of nitrogen fertilizers on growth and nitrogen uptake by Arawa and Hilgendorf wheat varieties, and on soil exchangeable ammonium and nitrate nitrogen levels : 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, 1972) Young, A. W.The essentiality of nitrogen for plant growth has long been established. However, the forms in which plants usually take in nitrogen from soils, have not been fully elucidated. It is commonly accepted that both exchangeable ammonium (NH₄-N) and nitrate (NO₃ -N) nitrogen are equally available to most plants, although more recent works have indicated that some plants can utilise a wide range of amino acids directly. Studies of changes in the levels of soil ammonium and nitrate nitrogen under wheat crops in Canterbury have led Ludecke (1972) to conclude that Arawa wheat plants could not use exchangeable ammonium directly as a nitrogen source. The present study was undertaken to examine this factor further. For this purpose, a second variety of wheat, Hilgendorf, which is more acid tolerant than Arawa, was also included. A pot trial was set up using four different forms of nitrogen fertilizer. A nitrification inhibitor, 'N-Serve', was used together with one of the fertilizer forms in an attempt to create different levels of soil exchangeable ammonium and nitrate, and to examine the effect of this on wheat performance. ItemEffect of ammonium and nitrate on nitrogen fixation and mineral nutrition of ryegrass and uninoculated and inoculated clover grown separately and in association : 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, 1977) Crisp, P. N.The present investigation presents data on the growth and ionic composition of ryegrass (Lolium perenne L.), and uninoculated and inoculated white clover ( Trifolium repens L.) plants, grown in nutrient solutions containing either NH₄- or No₃-N. The effect of increasing nitrate concentrations on the growth and ionic composition of ryegrass, and the growth of both uninoculated and inoculated clover, was also studied. In addition, the growth and ionic composition of either uninoculated or inoculated clover grown in association with ryegrass was studied at one N level with either NH₄ or NO₃ as the N-source. ItemA review of legume research and extension in New Zealand (1990-2022)(CSIRO Publishing, 2023) Moot, Derrick; Cullen, BLegumes have underpinned transformational change on New Zealand sheep and beef farms over the last 30 years. This was through an emphasis on ewe nutrition based on lucerne or red clover dominant pastures, and increased use of subterranean and white clovers on uncultivatable hill country. Pre- and post-weaning lamb growth rates have increased, and enabled earlier slaughter of heavier lambs. The farm systems results include greater numbers of hoggets mated, higher lambing percentages and greater ewe efficiency (kg lamb weaned/kg ewe mated). Extension packages to support legume use have compared growth rates of resident and legume-based pastures, economic analyses of successful farms and management packages for the most appropriate legume in different environments. Over the same period, the dairy industry rapidly expanded in cow numbers and area onto flat irrigated land on the Canterbury Plains. The nitrogen deficiency of perennial ryegrass was overcome by a linear increase in nitrogen fertiliser use. Environmental concerns from this intensification has led to a legislated nitrogen cap of 190 kg/ha.year. This, coupled with a recent trebling in urea price, has returned attention to increasing the white clover content of these pastures. Nitrogen applications can be minimised by using diverse pastures sown with a legume, herb and <8 kg/ha of perennial ryegrass. Work on other legumes, including annuals and those with condensed tannins, has to date failed to increase their use in most pastoral settings, with the exception of the perennial lupin which is adapted to high-aluminium soils in the South Island High Country. ItemReproductive performance of a cohort of Standardbred mares under a commercial breeding system(John Wiley & Sons Ltd on behalf of EVJ Ltd., 2023-08-09) Tanner, Jasmine; Barrell, GBackground: Despite being a large commercial breeding industry, there is little published data on the reproductive success of Standardbred mares. Objectives: To quantify the reproductive performance of Standardbred mares under artificial breeding systems in a commercial setting and determine the incidence of early embryonic and other pre-partum losses. Study design: Retrospective cohort study. Methods: Data from four commercial farms were collected across four breeding years, and all mares were bred via artificial insemination. A total of 3995 mares contributed 7229 mare years. First-cycle pregnancy rate (FCPR) and end of season pregnancy rate (SPR) were analysed in mixed-effects logistic regression models. Time-to-conception interval was analysed in a Cox regression model. Results: The mean FCPR was 61.4% (confidence interval [CI] 60.3%–62.6%), the mean end of SPR was 84.7% (CI 83.8–85.5%), the mean live foal rate (FR) was 73.1% (CI 72.1%–74.2%). Mares located on-farm were more probable to be pregnant in terms of both FCPR (odds ratio [OR] 1.168, CI 1.018–1.340, p = 0.026) and SPR (OR 2.026, CI 1.673–2.454, p < 0.001), mares inseminated with thawed–frozen semen were less probable to be pregnant in terms of FCPR (OR 0.598, CI 0.457–0.783, p < 0.001) and SPR (OR 0.479, CI 0.354–0.647, p < 0.001) compared with insemination with fresh-extended semen. Older mares (14 years and older) were less probable to be pregnant in terms of FCPR (OR 0.795, CI 0.688–0.919, p = 0.002) and SPR (0.435, CI 0.352–0.538, p < 0.001) compared with young mares (3- to 8-year old). Main limitations: Retrospective data relied on accurate record keeping of stud farms and no mare-treatment or ovulation induction records were available. Live FRs relied mostly on annual foaling returns so fetal/foal deaths may be underrepresented. Conclusion: This study provides substantial baseline data on reproductive performance for Standardbred mares managed under a commercial artificial breeding system. ItemAutomatically identifying sickness behavior in grazing lambs with an acceleration sensor(MDPI, 2023-07) Fan, B; Bryant, Racheal; Greer, AndrewAcute disease of grazing animals can lead to alterations in behavioral patterns. Relatively recent advances in accelerometer technology have resulted in commercial products, which can be used to remotely detect changes in animals’ behavior, the pattern and extent of which may provide an indicator of disease challenge and animal health status. The objective of this study was to determine if changes in behavior during use of a lipopolysaccharide (LPS) challenge model can be detected using ear-mounted accelerometers in grazing lambs. LPS infusion elevated rectal temperatures from 39.31 °C to 39.95 °C, indicating successful establishment of an acute fever response for comparison with groups (p < 0.001). For each of the five recorded behaviors, 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, there were significant effects of LPS infusion by hour interaction on durations of eating (−6.71 min/h, p < 0.001), inactive behavior (+16.00 min/h, p < 0.001), active behavior (−8.39 min/h, p < 0.001), and highly active behavior (−2.90 min/h, p < 0.001) with a trend for rumination time (−1.41 min/h, p = 0.075) in lambs after a single LPS infusion. Results suggest that current sensors have the capability to correctly identify behaviors of grazing lambs, raising the possibility of detecting changes in animals’ health status.