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Item Investigations on black soldier fly (Hermetia illucens L.) production and nutrition : a sustainable solution for poultry feeding : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science, School of Agriculture and Environment, College of Sciences, Massey University, Palmerston North 4442, New Zealand(Massey University, 2024-08-20) Mahmoud, Amira Elsayed AbdallaBlack soldier fly (BSF; Hermetia illucens L.) is renowned for efficiently converting organic wastes into valuable biomass rich in protein and fat. This makes it a profitable and sustainable method for waste management and a useful feed source for animals like poultry, fish, pigs, and pets. Using BSF reduces the dependence on traditional feed ingredients such as soybean and fish meal, which are often imported and add to the carbon footprint. Despite growing interest and large-scale production of BSF meals, knowledge gaps hinder the widespread adoption of this technology, especially in small and medium-scale operations. The overall aim of this multidisciplinary research was to better understand the biology and rearing methods of BSF, processing of insect meals, and their utilisation by broiler chickens. The thesis research specifically investigated: (1) methods and techniques that optimise BSF breeding and meal processing relevant to small and medium-sized operations, (2) the impact of substrate type, moisture, and compaction on the non-feeding stages of BSF, (3) disease management in BSF colonies to ensure healthy population dynamics, including the first record of red mites as a parasitic case within BSF colonies, and (4) the nutritional value of the larval and pre-pupal stages of BSF as replacements for soybean meal (SBM) in poultry feeds. Firstly, the thesis provided a practical guide to establishing and managing a BSF colony, covering the entire process from egg production to larval and pre-pupal meal processing. The procedures were based on the experience of producing 450 kg of BSF larvae (BSFL) and pre-pupae (BSFP) over the course of doctoral research. Secondly, a study examined the impacts of substrate type, moisture levels, and compaction on BSF pupation success, adult emergence and morality. Among the six substrates evaluated (sand, wood shavings, topsoil, vermiculite, spent wheat middlings, and potting soil), spent wheat middlings presented as the most cost-effective and readily available option. Moisture level was found to significantly affect substrate performance, with 10% moisture providing the best outcomes for pupation and reducing mortality while avoiding mould growth. Mild compaction did not negatively impact pupation development, suggesting that moderate compaction could enable small farmers to reuse substrate and lower the cost. Thirdly, an infestation of poultry red mites (Dermanyssus gallinae), causing noticeable skin discoloration and anatomical damage to the BSFL and BSFP, was identified. The mites repeatedly bit and fed on the BSF bodily fluids, causing distress. The implications of mite infestation on colony health and viability are discussed, emphasising the need to maintain colony hygiene. Lastly, the apparent metabolisable energy (AME) and standardised ileal digestibility coefficients (SIDC) of amino acids (AA) of full-fat BSFL and BSFP meals for broiler chickens were determined. The AME and SIDC of BSFL and BSFP were higher than those reported for SBM, the commonly used protein meal in poultry diets. The findings demonstrated that BSFL and BSFP meals are better sources of energy and digestible AA, and are potential substitutes for SBM. Although the principles behind BSF bioconversion technology may seem straightforward, effective implementation requires deeper understanding of its complex stages. The present thesis provided a thorough overview of BSF technology, including rearing methods, optimising pupation conditions, the identification of a novel ectoparasite affecting BSF colonies, and the potential use of BSFL and BSFP into broiler chicken diets. By addressing these key aspects, the research contributes valuable insights for optimising BSF production and utilisation, particularly for small and medium-scale operations.Item Understanding the variations in grazing and rumination behaviours and their associations with production parameters in individual grazing dairy cows : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Animal Science at Massey University (Manawatū) New Zealand(Massey University, 2023) Iqbal, Muhammad WasimThis thesis aimed to understand: 1) the accuracy of an accelerometer-based sensor to monitor grazing and rumination behaviours in dairy cows; 2) grazing and rumination behaviour patterns and time budgets over 24 hours; 3) potential factors to influence grazing and rumination behaviours; and 4) effects of grazing and rumination behaviours on production parameters. To do this, data including, but not limited to, grazing time, rumination time, measures of cow performance (e.g., milk production and composition, body weight and body condition score), days in milk, and breeding worth index of 162 grazing dairy cows were collected for three consecutive lactation seasons (2018-2021). The analysis was performed on individual study years and results were reported separately for each year. First, the accuracy of AfiCollar, an accelerometer sensor-based automated device to monitor and record grazing and rumination behaviours in dairy cows was evaluated for a grazing-based system. Spring-calved lactating cows (n = 48) wearing AfiCollar were continuously visually observed for 8 hours (9 am to 5 pm) to quantify minutes per hour spent grazing and rumination. The behaviours being observed were also recorded with the AfiCollar and compared with visual observations using Pearson’s correlation coefficient (r), concordance correlation coefficient (CCC), and linear regression. A strong association was found between the data collected by AfiCollar and the data obtained through visual observation for grazing time (r = 0.91, CCC = 0.71) and rumination time (r = 0.89, CCC = 0.80) with a significant linear relationship between both datasets (p<0.05). Furthermore, variations in the temporal patterns (min/h) and time budgets (% min/day) of grazing and ruminating behaviours recorded using AfiCollar were evaluated in spring calving lactating (n = 162) Holstein-Friesian (HFR), Jersey (JE), and Holstein-Friesian Jersey crossbreed (KiwiCross, KC) cows in their different lactations (1st, 2nd, 3rd, 4th), and with different breeding worth index values (103151). A repeated measure design was performed in SAS using PROC MIXED considering the fixed effects of breed and lactation, the random effect of individual cows, and hours of the day as repeated measure to evaluate their effects on hourly patterns and time budgets of grazing, rumination, and idling behaviours. Regardless of the seasonal variations and feed consumed, cows spent most of their daytime grazing (with peaks around dawn and dusk) and most of their nighttime ruminating. Grazing and ruminating patterns were similar between cows from different breeds and lactations, however, JE cows grazed slightly longer than HFR and KC cows; and first-lactation cows grazed slightly longer than mature cows in their later lactations. The onset and cessation of grazing activity by the cows were adjusted according to varying day lengths by season. In addition, a general linear (PROC GLM) mixed model was fitted to test the effects of days in milk, breeding worth, breed, lactation year, individual cow, season, feed, and their interactions on variations in grazing time, rumination time and their relationship. Results indicated that grazing time varied among breeds in Year-2 and Year-3 and among lactation years in Year-1. Rumination time differed between breeds in only Year-3, and it remained the same within lactation years. Grazing time and rumination time varied among different seasons that were related to varying supplementary feeds. Days in milk, breeding worth (except Year-3), and the individual cow had effects (P<0.05) on grazing and rumination times. Grazing time and rumination time had a negative relationship with each other that varied between different seasons but remained the same among different breeds and lactation years. The variance in grazing and rumination times was mostly explained by individual cows (up to 24%), season (up to 12%), and feed (up to 8%). Moreover, results also showed that grazing and rumination times had positive associations with milk yield, fat, protein, and solids. Grazing time had negative and rumination time had positive associations with liveweight, while both grazing time and rumination time had negative associations with body condition score. Grazing time explained up to 1%, and rumination time explained up to 7% of the variance in milk yield, milk fat, protein, and solids. AfiCollar can reliably monitor grazing and rumination behaviours in dairy cows, however, its accuracy can be improved for a grazing-based system. The animal itself, the season, and the feed are the potential sources of variation in grazing and rumination behaviours and should be considered for management decisions to address the animal’s behavioural requirements. Grazing and rumination behaviours are moderately correlated with performance parameters and explain a small proportion of variance in animal productivity.Item Feed not food : alternative feedstuffs for growing-finishing pigs : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Manawatu, New Zealand(Massey University, 2023) Nguyen, ThanhConventional diets used in the swine production sector, which rely heavily on soybean meal (SBM) and cereal grains, do not align with sustainable development goals. Hence, exploring alternative feedstuffs that are inexpensive, environmentally friendly, and do not compete with human food sources is essential to meeting future expectations around sustainability. As pigs are omnivores, they can efficiently convert many types of feed into a nutritious protein source for human consumption. Therefore, research and development in alternative feedstuffs for pigs are ongoing, and farmers are encouraged to adopt these options to enhance the sustainability of their operations. However, incorporating alternative feedstuffs in the diets of grower-finisher pigs requires proper risk management as they can contain high levels of insoluble fibre and other anti-nutritional factors that may affect pig growth performance, pork quality, and welfare. This thesis aimed to investigate alternative ingredients for inclusion in growing-finishing pig diets. The first experiment (Chapter 3) examined the effect of replacing barley, SBM and soybean oil with dried distiller’s grains with solubles, canola meal, wheat middlings and tallow on pig growth performance and meat quality. There were no negative effects of the alternative diet on overall pig growth or carcass performance, however, skatole levels of backfat were significantly lower in pigs fed the alternative diet. The second experiment (Chapter 4) investigated the effect of lucerne as an ingredient in grower-finisher diets and as manipulable enrichment material on pig growth performance and behaviour. Feeding the lucerne diet reduced average daily feed intake, live weight gain, feed intake per feeder visit, and feeding rate, but increased feed efficiency. Despite these effects, overall performance was not significantly different between treatments when considering feed conversion ratio, final slaughter weight, dressing out percentage and backfat thickness. The third experiment (Chapter 5) investigated the effect of replacing SBM with Poultry by-product meal (PBM) in growing-finishing pig diets on growth performance, carcass yield and meat quality. Four experimental diets were formulated, in which SBM was replaced with PBM at the increasing level of 0%, 33%, 77% and 100%. The diets were then fed to growing-finishing pigs. The results clearly demonstrate that PBM can be used as the primary protein source in pig diets without compromising the performance of growing pigs, as long as the diets are properly formulated to meet their nutritional requirements. A meta-analysis (Chapter 6) was conducted to assess the impact of substituting SBM with alternative oilseed meal, including canola meal, camelina meal, cottonseed meal, sunflower meal and rapeseed meal, on the performance of growing-finishing pigs. The findings indicate that this replacement adversely affected pig's daily weight gain while maintaining daily feed intake, resulting in an increased feed conversion ratio for both growers and finishers. Furthermore, the use of alternative oilseed meals led to reducing carcass and loin yield, although there was no significant impact on meat quality. However, the heterogeneities of the analysis for most parameters were substantial, possibly due to the variation in the nutritive value of the alternative oilseed meal. Overall, the results showed that substituting conventional feed ingredients with alternative feedstuffs had no or minor impacts on pig growth performance and meat quality. Additionally, several benefits of using alternative feedstuffs ingredients in growing pig diets were identified: reducing skatole in pork from entire males and improving feed conversion efficiency. The present research indicates that using alternative feedstuffs can be a viable option for pig feed, with possible benefits for pig production, meat quality and animal welfare. The field of alternative feedstuffs for pigs has much to explore, with numerous undiscovered options, such as legumes, brassicas, insects, and by-products, which can offer valuable nutrients and support sustainable pork production. These alternative feedstuffs may have multiple benefits, such as improved gut utilization, support for pig health, lower production costs, and reduced environmental impact. Furthermore, using feed additives to enhance the utilization of low-nutritive-value alternative feedstuffs is a viable option. As such, further research should focus on integrating these feedstuffs into pig diets while promoting sustainable development.Item Investigation of tropical pasture species to improve dairying in the tropics : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Manawatū, New Zealand(Massey University, 2023) Jayasinghe Mudiyanselage, Priyanath JayasingheDespite the ever-increasing demand for dairy products, dairy production in tropical regions is often lower than in temperate regions, due to a range of factors including the lower nutritive value of pastures. The availability of high-quality tropical pastures is a key requirement to increase the productivity of dairy cows as well as manage enteric methane emissions. Warm-season perennial grasses are the dominant forages in tropical and subtropical regions, and thus exploring their nutritive characteristics and evaluating their likely performance in existing dairy production systems, is imperative in the effort to improve dairy productivity. This thesis was undertaken to investigate tropical pasture species for improving dairying in the tropics via a modelling and simulation approach. A dearth of data comparing the nutritive values of tropical pastures grown across different environments limits the selection of forages for livestock in the tropics. A database was constructed containing a total of 4750 records, with 1277 measurements of nutritive values representing 56 tropical pasture species and hybrid cultivars grown in 26 different locations in 16 countries, in order to compare the nutritive values and greenhouse gas production across different forage species, climatic zones, and defoliation management regimes. The average edaphoclimatic (with minimum and maximum values) conditions within this data set were characterized as 22.5°C temperature (range 17.5–29.30°C), 1253.9 mm rainfall (range 104.5–3390.0 mm), 582.6 m elevation (range 15–2393 m), and a soil pH of 5.6 (range 4.6–7.0). The data revealed spatial variability in nutritive metrics across bioclimatic zones and between and within species. The ranges of these nutrients were as follows: neutral detergent fibre (NDF) 50.9–79.8%, acid detergent fibre (ADF) 24.7–57.4%, crude protein (CP) 2.1–21.1%, dry matter (DM) digestibility 30.2–70.1%, metabolisable energy (ME) 3.4–9.7 MJ kg⁻¹ DM, with methane (CH₄) production at 132.9–133.3 g animal⁻¹ day⁻¹. The arid/dry zone recorded the highest DM yield, with decreased CP and high fibre components and minerals. Furthermore, the data revealed that climate, defoliation frequency and intensity, in addition to their interactions, have a significant effect on tropical pasture nutritive values and CH₄ production. Overall, hybrid and newer tropical cultivars performed well across different climates, with small variations in herbage nutritive value. Results revealed that greater pasture nutritive values and lower CH₄ production can be potentially achieved through the selection of improved pastures and subsequent management. Subsequently, the suitability of three improved tropical perennial pastures: Chloris gayana ‘Rhodes grass cv. Reclaimer’ (RR), Megathyrsus maximus ‘Gatton Panic’ (GP), and Brachiaria ruziziensis x B. decumbens x B. brizantha ‘Brachiaria Mulato II’ (BM) for tropical dairy production was evaluated using their carbon assimilation, canopy structure, herbage plant-part accumulation and nutritive value parameters under irrigated conditions. A field experiment was conducted at Gatton Research Dairy (27° 54′ S, 152°33′ E, 89 m asl) Queensland, Australia, which has a predominantly subtropical climate. Photosynthesis biochemistry, canopy structure, herbage accumulation, plant-part composition, and nutritive value were evaluated. Photosynthesis biochemistry differed between pasture species. The efficiency of CO₂ assimilation was highest for GP and quantum efficiency was highest for BM. Pasture canopy structure was significantly affected by an interaction between pasture species and harvest. Forage biomass accumulation was highest in GP, while BM produced more leaves and less stem compared to both GP and RR. A greater leafy stratum and lower stemmy stratum depth were observed in the vertical sward structure of BM. Brachiaria Mulato II showed greater carbon partitioning to leaves, leaf: stem ratio, canopy, and leaf bulk density. The BM also demonstrated greater nutritive value (Total digestible nutrients (TDN), ADF, NDF, neutral detergent insoluble protein (NDICP), starch, non-fibre carbohydrates (NFC), ME, mineral profile (Mg, P, K, Fe, Zn) and dietary cation-anion difference (DCAD)) for leaf, stem, and the whole plant. Overall, the observed greater quantum efficiency, leaf accumulation, and nutritive value of BM suggested that BM is an attractive forage option for dairying in pasture-based systems in tropical and subtropical climates. The DairyMod-SGS, a mechanistic biophysical pasture model was parametrised and robustly validated for the prediction of the growth of the three tropical pastures (BM, GP, and RR), aiming to use the model as an effective tool to explore the likely performances of newer species under different edaphoclimatic and agronomic management practices. The model was calibrated using measurements of biomass components, canopy structure, and carbon assimilation collected from the field experiment at the Gatton Research Dairy Farm. Subsequently, the model was tested extensively using the published and unpublished data (16 data sets, 32 experiments, 14 different locations across South America, North America, Australia and Africa) to ensure that the parameterised model performed well and was reliable across a diverse set of environments and management practices. In the model parameterisation stage, the model predicted the above-ground biomass with good agreement for all tropical pastures with a high R² of 0.92, 0.98, 0.74 and low RMSE of 341, 583, 848 kg DM ha⁻¹ for BM, GP, and RR, respectively. The model agreement was good for the validation data with R² of 0.86, 0.80, 0.87 and RMSE of 954.5, 790.5, and 633.2 kg DM ha⁻¹ for BM, GP, and RR, respectively. The predicted leaf and stem partitioning was relatively poor, and the model also struggled to simulate realistic pasture growth in Mediterranean and desert environments (R² < 0.50). The present study has improved the robustness and accuracy of DairyMod-SGS in relation to tropical pastures and indicated that the model can be successfully used for investigating the likely performance of improved tropical pastures under a broad range of conditions. The validated DairyMod-SGS pasture model was applied to simulate the long-term pasture production of three improved pastures (BM, GP, and RR) in major dairying regions of Sri Lanka under three management scenarios: 1) rainfed pasture production system under the industry average nitrogen (N) fertiliser rate (Yₜᵂᴺ = yield over time under water and N limitation); 2) rainfed pasture production system under non-limiting N fertilisation (Yₜᵂ = yield over time with no N limitation but water limitation); and 3) potential pasture production system under non-limiting N and irrigation (Yₜ = yield over time with no N and water limitations). Simulations were carried out for 16 sites across Sri Lanka (8 sites in the dry zone (DZ), 5 sites in the intermediate zone (IZ), and 3 sites in the wet zone (WZ)) over a 30-years period (1980–2010). The model simulated that the long-term pasture production greatly varied between climate zones, pasture species and management scenarios. Overall, the Yₜᵂᴺ scenario showed a seasonal cycle following the rainfall pattern, with a reduction in growth rates in dry seasons (May to September). Growth rate and herbage accumulation were greater in GP at Yₜᵂᴺ, and BM at Yₜᵂ and Yₜ, while RR always showed the lowest growth rate. The variability of pasture growth between climate zones was highest in DZ (May to September) whereas the variability between species was lowest in RR. Pasture accumulation of both BM and GP outperformed their standard cultivars currently grown in Sri Lanka. In general, the pasture accumulation under Yₜᵂ increased (doubled) the growth rate, while the Yₜ scenario substantially increased (nearly tripled) the growth rate. Overall, the finding of this thesis suggested that all three pasture cultivars tested (BM, GP, and RR) are suitable for growing across major dairying regions in Sri Lanka, and that appropriate fertiliser and irrigation management can greatly intensify the herbage accumulation. In particular, BM appeared to be promising in terms of nutritive value, and agronomic and physiological traits. However, regional edaphic conditions, and the management ability of the farmers with respect to inputs and defoliation management, will ultimately determine the performance of improved cultivars such as those used in this thesis. There is a need for extension activities to support farmers in the management required to achieve best performance (yield, nutritive value and persistence) from these species. Future research is recommended to: 1) validate the model under Sri Lankan conditions, using both unimproved and improved cultivars, to determine its suitability in estimating tropical pasture yield; and 2) use additional models to evaluate the performance of improved tropical pastures in the context of the whole farm system, to identify the likely impact on dairy production and economic return.Item Use of New Zealand native browse shrubs on sheep and beef hill country farms : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at the School of Agriculture and Environment, Massey University, Palmerston North, Manawatū, New Zealand(Massey University, 2023) Wangui, James ChegeSheep and beef cattle farming on hill country through the historic clearing of native vegetation for pasture has caused biodiversity loss and increased the risk of soil erosion. Exotic tree species such as poplar and radiata pine can be used to control erosion, but there is current interest in using native plants on the hill country for indigenous biodiversity restoration in addition to erosion control. However, there is limited information on the forage value, biomass, carbon stock, and potential economic impacts of native plants compared to exotics species. This thesis was aimed to address the lack of information available on native shrubs and their comparison to exotics trees and shrubs. The forage feeding value results revealed that native shrubs had consistent nutritional composition across seasons, higher metabolizable energy, and lower crude protein than the exotic shrub Salix schwerinii (Kinuyanagi). Findings on in vitro fermentation characteristics showed that native shrubs were highly digestible, yielded higher volatile fatty acids, microbial proteins, and greenhouse gases than S. schwerinii. Estimation of biomass revealed that the native shrubs were similar in aboveground biomass accumulation, but differed in allocation to foliage, branch, and stem. Melicytus ramiflorus (Mahoe) had lower foliage biomass while Coprosma robusta (Karamū) had lower branch biomass, among the evaluated shrubs. Estimated carbon stock accumulation was higher for Pittosporum crassifolium (Karo) due to a greater woodier portion (branch and stem) than M. ramiflorus and C. robusta but lower than exotic trees. The data from the native shrub studies was used in the bioeconomic model and showed that planting native shrubs or radiata pine on steep slopes equal to 10% of the farm area would reduce farm feed supply. This reduction would result in a decrease in sheep flock size and sheep flock net cashflow, particularly with higher planting rates and with of radiata pine. While radiata pine had a surplus overall farm net cashflow, native shrubs had negative cashflow due to high seedling costs and low carbon income, making their use on the farm currently unprofitable at the modelled prices. The study's findings suggest that replacing exotic trees with native shrubs can provide high-quality summer browse for livestock. The decision to plant native shrubs on steep hill country slopes would depend on the farmer’s financial situation and interest in biodiversity conservation and profits. However, reducing planting costs and increasing the carbon price would be necessary to make investing in native shrubs profitable and more attractive to farmers.Item Physiological effects of dietary moisture in cats (Felis catus) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science, Massey University, Palmerston North, New Zealand(Massey University, 2022) Hekman, MargreetThere is no system in the mammalian body that does not depend on water. Water is an essential nutrient and comprises approximately two thirds of a domestic cat’s body weight. It is recommended that sufficient water is provided to domestic cats to allow self-regulation of intake, encompassing both voluntary drinking and intake of dietary moisture. Understanding the role of dietary moisture in health and disease in domestic cats, however, has thus far been neglected, and any physiological differences between cats consuming either high moisture (HM) or low moisture (LM) diets, have been assumed unimportant. Therefore, to fill this gap in the literature this thesis investigates the effects of consuming HM and LM diets in healthy cats and cats diagnosed with chronic kidney disease. By feeding cats diets which were created to differ in dietary moisture content only, this work aimed to determine if single or multiple meal feeding of a LM food influenced total water intake (TWI), urine concentration and pH, plasma osmolality (POsm), blood pressure (BP), water balance, and activity in cats when compared to free access HM food feeding (Chapters 2 and 3). Then the effect of a single meal and a single simulated meal on post-prandial BP and heart rate using the same diets was investigated (Chapter 4). Further, using these diets, the molecular weight distribution of urinary proteins was quantified and described (Chapter 6), and the effects of a meal on post-prandial vasopressin (VP) and copeptin concentrations were investigated (Chapter 7). Lastly the diets were used to compare the effects of consuming a HM and LM diet on urine concentration and pH, POsm, plasma VP, and BP, in cats recently diagnosed with chronic kidney disease (Chapter 8). Additionally, due to the difficult and inaccurate nature of VP hormone analysis, several alternative methods to quantitate the VP proxy copeptin were investigated, however these were unsuccessful (Chapter 5). It was found that TWI and output were significantly lower when healthy cats were fed LM diets compared to HM diets and increasing meal frequency of LM diets did not increase TWI. This difference in TWI did not result in a difference in BP or total urinary protein content. However, lower TWI did lead to a decrease in water turnover rate, and increased urine concentration, POsm, and plasma VP levels. Therefore, varying dietary moisture has meaningful physiological effects in the cat. In addition, the results may indicate increasing adverse effects on health when TWI is low, with particularly detrimental effects to the kidney. Furthermore, there were modest indications that additional adverse effects such as increasing urine protein to creatinine ratio appeared when older cats were fed LM diets. Therefore, it is proposed that the role of dietary moisture is significant for the health of domestic cats, especially as they age, and that primarily feeding a LM diet and allowing self-regulation of water intake through voluntary drinking does potentially not secure a high enough TWI for their long-term health. Feeding a HM diet ensures a high TWI, which may have clinical implications for rehydration of ill cats, especially in cats diagnosed with chronic kidney disease, and potentially may even prevent or delay progression of disease in healthy cats. Feeding a HM diet should primarily be considered when a greater water intake is required to counter dehydration, or in the treatment of diseases that benefit from an increase in water intake.Item The effects of the application of large amounts of nitrogen fertilizer on milk yield, reproductive performance, and energy balance of spring-calved high genetic merit cows : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Sciences in Animal Production at Massey University, Palmerston North, New Zealand(Massey University, 2005) Ordóñez, AlfredoThe intake of crude protein (CP) in amounts considerably above the cow's requirements has been associated by several overseas (OS) reports with reduced cow performance. In New Zealand (NZ), the CP content of pasture during spring is usually above the cow's requirements. During this time, application of nitrogen (N) fertilizer is a common practice which further increases the CP content of pasture. Despite this fact, few experiments have studied the effect of high CP intake on cow performance in NZ, and the existing results are not conclusive. Therefore, the objective of this experiment was to measure the effect of two levels of CP concentration in pasture caused by application of different amounts of N fertilizer, on milk yield, reproductive performance, and energy balance of grazing, spring-calved, high genetic merit cows in NZ. Two groups, each of 20 high genetic merit cows, were offered a common pasture allowance (46 kg OM/cow/day) over the first 101 days postcalving, but from pasture which contained either a lower (low CP group) or a higher concentration (high CP group) of crude protein. The difference in CP concentration was created by applying either no N fertilizer or 35 kg of N fertilizer after every grazing. Herbage masses were measured on every paddock weekly, and every day pregrazing and postgrazing, using a rising plate meter. These values were used to calculate pasture growth, and apparent dry matter intake per group. Pasture composition was measured by near infrared spectroscopy. For each cow, milk yield and composition was measured by weekly herd tests. Reproductive performance was assessed by scanning of follicles and corpora luteal from day one until day 40 postcalving, and from 10 days before the predicted artificial insemination (Al) until 35 days post Al. Progesterone concentrations were measured in milk samples taken every second day. Liveweight and condition score of each cow were measured weekly, and concentrations of NEFA and IGF1 were measured in blood samples taken II once every week. Energy balance was calculated as theoretical energy requirements minus estimated energy intake, and feed conversion efficiency was also calculated. When compared with the low CP paddocks, the high CP paddocks produced more pasture (+1,260 kg OM/ha in 101 days) and it was of higher quality (11.8 vs. 11.4 MJ ME/kg OM; 83.4% vs. 81.2% digestibility; 24.5 vs. 21.6% CP). The apparent daily intakes of OM and ME of the two groups were not significantly different (16.2 and 15.9 kg OM/cow; 195 and 184 MJ ME/ cow). However, the high CP group ate significantly more CP than the low CP group (4.2 vs. 3.5 kg CP/cow/day, and had a higher blood urea concentration (7.8 vs. 5.3 mmol/I). There were no significant or consistent differences between the two groups in milksolids yield (1.84 vs. 1.91 kg MS/cow/day for the high and low CP groups), reproductive measurements, liveweight, condition score or IGF1 concentrations. However, the high CP group had significantly lower NEFA concentrations than the low CP group (0.45 vs. 0.56 mmol/I). The high CP group had lower apparent feed conversion efficiency than the low CP group, which may have been partially due to the calculated value of 3.2 MJ ME extra required per day to excrete the extra urea from the high CP group. In conclusion, even though the high CP group had higher blood urea concentrations, no significant differences in cow performance were detected between the two groups. The application of 130 kg N/ha produced an extra 1,264 kg OM/ha, which would have been expected to produce an extra 140 kg MS/ha, although this increase in MS yield may have been reduced slightly (by 9%) by the lower calculated feed conversion efficiency of the high CP group. Subject for further research include attempts to increase the feed conversion efficiency of animals grazing pastures with high CP content, through the use of sources of extra rumen degradable energy; the effect of diets high in CP on embryo quality and viability; and the ecological impact of using large amounts of N fertilizers.Item Nutrient leaching under intensive sheep grazing : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Manawatu, New Zealand(Massey University, 2023) Maheswaran, SarminiThe use of some alternative forages may help sheep farmers to reduce nitrogen (N) leaching while increasing production. This thesis explores the effects of four forages (perennial ryegrass/white clover: RGWC; Italian ryegrass/white clover: IRWC; plantain/white clover: PWC; and a winter brassica) on sheep performance, urinary N excretion and N loss in drainage over two and a half years (Year 1: July to December 2019; Year 2: January to December 2020; Year 3: January to December 2021). This study was conducted on an artificially drained, fine textured Tokomaru silt loam soil at Massey University’s Keeble farm, near Palmerston North, Manawatu, New Zealand. The study design included four self-contained farmlets (each approximately 3.3 ha): three farmlets had 0.8 ha (24% of their grazing area) sown to include one of three alternative forages (IRWC or PWC or brassica), and the remaining 2.5 ha was sown in a perennial ryegrass/white clover sward. The entire area (100% of grazing area) of the fourth farmlet was sown in RGWC. Approximately 0.4 ha of each farmlet was located in a paddock where a series of 20 drainage plots (each 40 m by 20 m) were established to measure N leaching. Each of the alternative forages, and the RGWC, were sown on five of the drainage plots i.e., five replicates (combined area of 0.4 ha), which composed about one-half of the area of each alternative forage on each farmlet. The amount of N leached through a mole-pipe network on each drainage plot was also measured. Breeding ewe productivity including liveweight, condition score and lambing performance, as well as N excretion was also measured. In addition, forage growth and DM production were monitored along with chemical and botanical composition. The inclusion of alternative forages into the RGWC system did not affect animal performance. This was due, in part, to animal management. The N leached under various forages was, therefore, able to be compared without the confounding effects of differences in animal performance. The daily urinary N excretion per animal by sheep grazing PWC or brassica was lower (18 to 70%) than the daily urinary N excretion by sheep grazing RGWC or IRWC. It is likely that the diuretic effect of plantain and a lower N concentration in the brassica caused lower N concentrations in urine. Nitrate (NO₃⁻) leaching losses under RGWC, IRWC and PWC were very small in Years 1 and 2 (ranging from 0.4 to 0.8 kg N/ha). The poor persistence of IRWC and PWC at this site and the need to re-establish these forages on the plots resulted in greater NO₃⁻ leaching under these forages in Year 3, negating some of the advantages associated with these forages in Years 1 and 2. In contrast, NO₃⁻ leaching losses were greater under brassica forages (ranging from 0.4 to 6.4 kg N/ha) than under RGWC (ranging from 0.5 to 1.5 kg N/ha). Although sheep grazing brassica forages excreted less urinary N (on an individual animal basis), leaching losses under the brassica treatments were higher. In addition to the effect of cultivation, this increased leaching was likely because brassica plots were grazed for a more extended period during winter than other forages, and there was no crop (forage) cover until the spring resowing; therefore, the urinary N accumulated during winter grazing was displaced by subsequent drainage. With the assumption that the cropped area occupies a relatively small portion of the farm, grazing brassica is likely to result in a relatively small increase in whole farm NO₃⁻ leaching. Overall, NO₃⁻ leaching losses under sheep grazing forages were lower (ranging from 0.5 to 9.5 kg N/ha) than those reported under dairy cattle grazing forages, which suggests that sheep production may offer an alternative land use option for dairying areas where it is difficult to achieve the large reductions in NO₃⁻ leaching required to meet water quality objectives.Item Comparison of maize silage and traditional forage crops in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Manawatū Campus, New Zealand(Massey University, 2022) Thant, Aung MyoCattle wintering systems using crops including grazing kale, swede, and fodder beet crops in situ have resulted in soil and water quality deterioration. Nitrate leaching is the most common problem due to the high deposition of urine N driven by excess N intake. Alternative cropping systems offer a potential solution to reduce these environmental problems while maintaining or maximising productivity. We proposed maize silage as an alternative crop because it has high yield potential, flexible feeding requirements, compliments the nutritive value of pasture, and is potentially suitable for more regions in New Zealand in the future due to climate change. However, research needs to determine whether maize silage yield, feed quality and potential nitrate losses during production and utilisation means it is a viable alternative to in situ grazed forage crops in these areas. Field experiments were conducted at Massey University, Tokoroa and Kiwitea to determine forage yield and feed quality, management effects and site differences in 2018/19 and 2019/20. Crop yields and forage N content were utilised to simulate urine N loads from the feeding of these forage crops. The excreted N loads were analysed in APSIM (Agricultural Production Systems sIMulator) to predict nitrate leaching losses. Maize produced significantly higher yields compared with the winter forage crops at all Massey University trials while producing competitive yields at Tokoroa and Kiwitea. Yields ranged from 10,940 to 30,417 kg DM/ha for maize whilst wide and lower yield ranges were observed for the winter forage crops (4,579 to 22,928 kg DM/ha). Irrigation increased yields of forage crops by 29-63%. Similarly, nitrogen fertiliser increased yield by 30%, on average. The faster canopy development of maize has the advantage of intercepting more radiation in summer and suppressing weeds, contributing to greater growth and yield despite a shorter crop season. All forage crops produced forage with good metabolisable energy content (MJ/kg DM); higher values in swede (10.1-14.5) and fodder beet (10.8-14.9) whereas intermediate values in kale (8.9-12.7) and maize (9.9-12.2). However, maize was the highest energy-yielding crop, ranging from about 200-316 GJ/ha while other crops varied from 34 to 217 GJ/ha. Protein content in kale (7.5-16.6% DM) and swede (11.4-18.2% DM) were adequate for non-lactating cows whereas maize (5.4-9.2% DM) and fodder beet (7.6-11.2% DM) were lower than recommended protein levels for dairy cows but offering an opportunity to reduce urinary N excretion. Maize also had recommended fibre content. With higher sugar contents, swede and fodder beet were poor in fibre sources, potentially prone to rumen acidosis unless considered mixed diet with high fibre feed. APSIM modelling indicated that maize would produce the lowest urine N output while swede the highest in simulated feeding. Accordingly, N loads/ha was higher for winter forage crops especially when good yields were produced. When common feeding practices were considered, i.e., off-paddock maize feeding (no urine N deposition) and on-paddock grazing of winter forage crops (high urine N deposition), simulated nitrate losses from maize cropping systems were the lowest. Predicted nitrate losses were 21 and 32 kg N/ha for maize under irrigated and non-irrigated conditions. A ryegrass cover crop further reduced simulated nitrate losses by 20-30%. Predicted nitrate losses for fodder beet, kale, and swede crops were 126, 162, 154 kg N/ha under irrigated conditions and 72, 201, 199 kg N/ha under non-irrigated conditions, respectively in grazing systems.Item Identification and characterisation of rumen bacteria with prominent roles in the ruminal metabolism of forages : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (Microbiology and Genetics) at Massey University, Palmerston North, New Zealand(Massey University, 2022) Mahoney-Kurpe, SamThis thesis documents the characterisation of two groups of rumen bacteria that are both prominent in forage-fed ruminants, with the aim to better understand their roles in ruminal metabolism. The first group, referred to as the R-7 group, has in recent years been shown to be one of the most abundant rumen bacterial groups, though the few isolated representative strains available were uncharacterised. Two strains of the group included in the Hungate1000 culture collection, R-7 and WTE2008, were selected for characterisation. To facilitate phylogenetic analyses of this group, the complete genomes of an additional three previously isolated R-7 group strains were sequenced. Genomic, phylogenetic and phenotypic characterisation of R-7 and WTE2008 demonstrated that despite their 16S rRNA gene sequences sharing 98.6-99.0% nucleotide identity, their genome-wide average nucleotide identity of 84% assigned them as separate species of a novel genus and family of the proposed order ‘Christensenellales’ using the Genome Taxonomy Database. Phenotypic characterisation showed that the strains were identical in morphology, and both possessed the ability to degrade plant cell wall polysaccharides xylan and pectin, but not cellulose. Acetate, ethanol, hydrogen and lactate were produced by both strains, though R-7 produced greater amounts of hydrogen than WTE2008, which instead produced more lactate. Based on these analyses, it is proposed that R-7 and WTE2008 belong to separate species (Aristaeella gen. nov. hokkaidonensis sp. nov. and Aristaeella lactis sp. nov., respectively) of a newly proposed family (Aristaeellaceae fam. nov.). The second bacterial group of interest, due to their dominant role in ruminal propionate production, was the Prevotella 1 group, following analyses of metatranscriptome datasets of rumen microbial communities of lucerne-fed sheep for dominant community members that express propionate pathway genes from succinate. Screening of 14 strains spanning the diversity of Prevotella 1 found that all except one P. brevis strain produced propionate in a cobalamin (vitamin B12)-dependent manner. To better understand the pathway and regulation of propionate production from succinate, a comparative multi-omics approach was used to test the hypothesis that propionate production is regulated by a cobalamin-binding riboswitch. Scanning of a completed genome assembly of Prevotella ruminicola KHP1 identified four ‘cobalamin’ family riboswitches. However, the riboswitches were not in close proximity to genes putatively involved in converting succinate to propionate, nor were these genes arranged in a single operon. Comparative genomics of the 14 screened strains found that all strains possessed all homologues of candidate propionate pathway genes identified in the KHP1 genome. However, the 13 propionate-producing strains possessed a putative transporter and three subunits encoding a putative methylmalonyl-CoA decarboxylase upstream but antisense to two genes encoding methylmalonyl-CoA mutase subunits, whereas the non-producing strain did not. Comparative transcriptomics and proteomics of KHP1 cultures in the presence and absence of cobalamin demonstrated that some gene candidates were upregulated by cobalamin at the transcriptome level, including co-located genes annotated as phosphate butyryltransferase and butyrate kinase, despite the strain not producing butyrate, suggesting that propionate production may occur via propionyl phosphate. However, only both subunits of methylmalonyl-CoA mutase showed greater transcript and protein abundances in the presence of cobalamin. These results show that while some propionate pathway candidate genes were differentially expressed between cobalamin treatments, they did not appear to be under direct control of a cobalamin-binding riboswitch. This study has contributed to our understanding of the roles of both Aristaeellaceae fam. nov. and Prevotella 1 in ruminal metabolism.
