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Item Bio-economic system-dynamics modelling to investigate strategic management options in New Zealand sheep farming enterprises : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Farm Management, School of Agriculture and Environment, Massey University, Manawatu, New Zealand(Massey University, 2020) Farrell, LydiaThe average and range of production and profit levels achieved in New Zealand sheep farming enterprises indicate potential for improvement across many farms. Ewe wastage, use of terminal sires, and breed transition to produce higher value wool are issues currently pertinent to the profitability of farms on New Zealand North Island Hill Country with dual-purpose breeding ewe flocks. A bio-economic system-dynamics sheep farm model was identified as appropriate to model these profitability scenarios where changes in ewe flock structure were integral. The objectives of the current research were: to develop the model; validate output through examining ewe flock wastage (premature ewe losses) rates; and use the model to investigate use of terminal (meat breed) sires to increase income from lamb sales, and a gradual flock breed transition from purebred Romney to ¾ Merino ¼ Romney to increase income from wool sales. Component modules were flock dynamics (including sheep sales), sheep feed demand, feed supply from pasture, feed balance, wool production, and economics. Model output aligned with previously published industry data and was therefore considered a realistic representation of New Zealand North Island Hill Country sheep farming systems. Flock wastage rates ranging from 5% to 21% were studied, sheep enterprise cash operating surplus (COS) reduced by $1,069 per 1% increase in ewe wastage rate due to reductions in numbers of lambs for sale. The scope for terminal sire use in self-replacing flocks was limited by requirements for purebred ewe lambs. The maximum proportion of the breeding flock able to be bred with terminal sires ranged from 18% to 65% and was greater with higher lambing rate and lower replacement rate. Maximising terminal sire use increased COS by up to $101/ha compared with no use of terminal sires, due to higher survival and growth rates in crossbred lambs sold earlier for higher prices. Flock breed transition through crossbreeding a Romney flock with Merino sires demonstrated reductions in COS during the breed transition period and greater COS post-breed change. Net present value analysis showed whole farm COS with breed transition to be up to 26% greater than maintaining the purebred Romney flock. Breed transition scenarios with higher Merino-Romney crossbred ewe lamb selection intensity achieved lower average wool fibre diameter, with a longer breed transition period (i.e. ten years of transition) and greater economic benefit. Overall, the model was effective in investigating the selected scenarios and the results can be used to inform decision making of New Zealand farmers.Item Removal of dissolved reactive phosphorus from municipal and dairy factory wastewater using allophanic soil : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science, Massey University, Palmerston North, New Zealand(Massey University, 2019) Cheuyglintase, SasikunyaMany of New Zealand’s sewage treatment plants (STPs) and rural factories discharge treated or partially treated sewage, which is rich in dissolved reactive phosphorus (DRP), into rivers and streams. A large number of these STPs are not able to comply with the current DRP river standards because conventional treatment methods are cost-prohibitive. There is an abundance of Allophanic soils with high phosphorus (P) sorption capacities located in the central North Island of New Zealand that have potential for use as low-cost filter material for removing DRP from wastewaters. For Allophanic soil filters to be a viable treatment option, the soil, in addition to having a high P sorption capacity, should be both accessible and plentiful. The main aims of this study were to assess and improve the effectiveness of Allophanic soil filters at removing DRP from wastewaters and to evaluate the agronomic value of P-enriched soils as a P source for plant growth. It also sought to contribute to a better understanding of the feasibility and important design characteristics of fullscale soil-based treatment systems. Five quarry sites in the Waikato Region were soil sampled to identify soils with high P retention values. Only the Te Mata Quarry (TQ) soil in the, northwestern Waikato Region, had a high P retention value at or close to 100% as assessed using the standard (5 g) anion storage capacity (ASC) test. The modified (1 g) ASC test revealed P retention values of 47 – 91% for samples taken from different soil depths at TQ. All of the soil depths down to 600 cm, except for the 125 – 175 cm depth, had modified (1 g) ASC test values >58%. This indicated that the TQ soil had P sorption capacities that would potentially make it a suitable material for filtering DRP from wastewater and, therefore, it warranted further evaluation using real wastewater. Wastewater pH has a marked influence on the P sorption capacity of soil filters, with the sorption capacity expected to increase as wastewater pH is decreased, from being alkaline to acidic. The laboratory soil column experiment quantified the effect of the level of acid dosing and the type of acid used on the capacity of soils to remove P from wastewater. Columns of soil, taken from a quarry at Ohakune (OQ), and treated with wastewater adjusted to pH 5.5 removed the greatest amount of DRP. A total of 8.9 mg P/g oven-dried soil was removed at an average removal efficiency of 75%. In comparison, the soil columns treated with wastewater without pH adjustment, removed only 4.5 mg P/g oven-dried soil at the same removal efficiency of 75%. This highlights the merits of lowering wastewater pH to increase DRP removal capacity. The performance pilot-scale soil filters at the Dannevirke STP and Fonterra Te Rapa WTP were evaluated, under field conditions, for a total operational period of 440 and 376 days, respectively. Each filter contained the OQ soil and had a surface area of 1 m². The OQ soil had an overall P removal efficiency of 67% and 71% at the STP and WTP sites, respectively. The OQ soil filters at Dannevirke STP removed a total of 6.4 mg P/g oven-dried soil, while the OQ soil filters at the Fonterra Te Rapa WTP removed a total of 1.87 mg P/g ovendried soil. This discrepancy in performance was due to the difference in wastewater type and pH adjustment, initial P concentrations, and soil pretreatment (i.e. the soil used at Dannevirke was sieved). A cost/benefit analysis suggested that if the STP was 225 km from the soil source then the cost of acid dosing is about ten times greater than the cost of supplying additional soil to achieve the same amount of P removal. Therefore, it is unlikely that acid dosing will be cost competitive for most wastewater treatment sites in the central North Island of New Zealand. The wastewater treated soil (WTS) obtained from the Dannevirke STP pilotscale filter experiment was evaluated for its agronomic effectiveness in a glasshouse pot experiment. The ability of WTS to supply P for ryegrass growth (Lolium multiflorum) was compared with a soluble phosphorus source (monocalcium phosphate, MCP). The WTS was highly effective at increasing available P in the soil, as measured by the Olsen P soil test, ryegrass yield and ryegrass P uptake. The soluble fertiliser P value of WTS was estimated to be equivalent to 61% of MCP applied at the same rate. Therefore, the results show that WTS is an effective P source for plant growth and its application to soil has the potential to recycle both the soil and the P it contains.Item Examining perennial ryegrass (Lolium perenne L.) persistence through identifying genetic shifts within two cultivars after nine years in the field : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Breeding at Massey University, Palmerston North, New Zealand(Massey University, 2019) O'Connor, Jessica RichellePerennial ryegrass (Lolium perenne L.) is a commercially important forage species in New Zealand agriculture. Ryegrass persistence is important for farmers as it substantially decreases the costs associated with reseeding pastures. Breeding for ryegrass persistence is difficult because of the complex interaction between genotype and environment; and the short time of field trial assessment compared to the expected longevity of pasture. A nine year old cultivar comparison trial at Poukawa, Hawkes Bay, New Zealand was identified and plants surviving in the cultivar plots of ‘Grasslands Samson’ and ‘Commando’ were retrieved. These populations that had survived were termed Persistent. A sample of commercially sourced seed of these cultivars were also grown to represent the ‘Original’ genetic pool of the cultivars sown in the field. Persistent populations were compared to Original cultivar seed to characterise morphology and underlying genetics associated with persistence. Results were interpreted to determine if a genetic shift had occurred in Persistent populations due to advantageous phenotypes surviving. Three methodologies were used to compare populations: 1) In a glasshouse, eight morphological traits were measured after 10 weeks growth for Original and Persistent populations of ‘Grasslands Samson’; 2) Half-sibling families were generated from Persistent and Original populations for both cultivars and were assessed for additive genetic variation of seven traits as one metre rows in the field over 13 months; 3) Simple sequence repeat (SSR) markers were used to explore the genetic composition of Original and Persistent populations of each cultivar. Analysis and interpretation of data showed genetic shifts were cultivar specific. The greatest differences were identified between populations of ‘Grasslands Samson’. Compared to the Samson Original population, Samson Persistent plants had significantly greater means for four traits in the glasshouse and half-sibling families showed evidence of shifting population means of traits associated with animal grazing avoidance. SSR marker results were confounded by late detection of contamination in samples. Analysis of a reduced sample size showed no significant differences between any of the four populations using F statistics and genetic structure analysis. These results suggest future studies could reduce risk of contamination by collecting single tillers from the field of Persistent populations. Further investigation of the genetics of persistence should focus on the role of lamina sheath lengths in tiller production, and using the half-sibling families identified in this study for germplasm development and quantification of genotype-by-environment interactions.Item Molecular epidemiology of waterborne zoonoses in the North Island of New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science (Epidemiology and Public Health) at Institute of Veterinary, Animal and Biomedical Sciences (IVABS), Massey University, Palmerston North, New Zealand(Massey University, 2016) Shrestha, Rima DeviCampylobacter, Cryptosporidium and Giardia species are three important waterborne zoonotic pathogens of global public health concern. This PhD opens with an interpretive overview of the literature on Campylobacter, Cryptosporidium and Giardia spp. in ruminants and their presence in surface water (Chapter 1), followed by five epidemiological studies of Campylobacter, Cryptosporidium and Giardia spp. in cattle, sheep and aquatic environment in New Zealand (Chapters 2-6). The second chapter investigated four years of retrospective data on Campylobacter spp. (n=507) to infer the source, population structure and zoonotic potential of Campylobacter jejuni from six high-use recreational rivers in the Wanganui-Manawatu region of New Zealand through the generalised additive model, generalised linear/logistic regression model, and minimum spanning trees. This study highlights the ubiquitous presence of Campylobacter spp. in both low and high river flows, and during winter months. It also shows the presence of C. jejuni in 21% of samples containing highly diverse strains, the majority of which were associated with wild birds only. These wild birds-associated C. jejuni have not been detected in human, suggesting they may not be infectious to human. However, the presence of some poultry and ruminant-associated strains that are potentially zoonotic suggested the possibility of waterborne transmission of C. jejuni to the public. Good biosecurity measures and water treatment plants may be helpful in reducing the risk of waterborne Campylobacter transmission. In the third study, a repeated cross-sectional study was conducted every month for four months to investigate the source of drinking source-water contamination. A total of 99 ruminant faecal samples and 24 river/stream water samples were collected from two rural town water catchments (Dannevirke and Shannon) in the Manawatu-Wanganui region of New Zealand, and molecular analysis of those samples was performed to determine the occurrence of Campylobacter, Cryptosporidium, and Giardia spp. and their zoonotic potential. The major pathogens found in faecal samples were Campylobacter (n=225 from 7/8 farms), followed by Giardia (n=151 from 8/8 farms), whereas Giardia cysts were found in many water samples (n=18), followed by Campylobacter (n=4). On the contrary, Cryptosporidium oocysts were only detected in a few faecal (n=18) and water (n=3) samples. Cryptosporidium and Giardia spp. were detected in a higher number of faecal samples from young animals (≤ 3 months) than juvenile and adult animals, whereas Campylobacter spp. were highly isolated in the faecal samples from juvenile and adult ruminants. RCRsequencing of the detected pathogens indicated the presence of potentially zoonotic C. jejuni and C. coli, Cryptosporidium parvum (gp60 allelic types IIA18G3R1 and IIA19G4R1) and Giardia duodenalis (assemblages AII, BII, BIII, and BIV) in cattle and sheep. In addition, potentially zoonotic C. jejuni and Giardia duodenalis assemblages AII, BI, BII, and BIV were also determined in water samples. These findings indicate that these three pathogens of public health significance are present in ruminant faecal samples of farms and in water, and may represent a possible source of human infection in New Zealand. In the fourth study, PCR-sequencing of Cryptosporidium spp. isolates obtained from the faeces of 6-week- old dairy calves (n=15) in the third study were investigated at multiple loci (18S SSU rDNA, HSP70, Actin and gp60) to determine the presence of mixed Cryptosporidium spp. infections. Cryptosporidium parvum (15/15), C. bovis (3/15) and C. andersoni (1/15), and two new genetic variants were determined along with molecular evidence of mixed infections in five specimens. Three main Cryptosporidium species of cattle, C. parvum, C. bovis and C. andersoni, were detected together in one specimen. Genetic evidence of the presence of C. Anderson and two new Cryptosporidium genetic variants are provided here for the first time in New Zealand. These findings provided additional evidence that describes Cryptosporidium parasites as genetically heterogeneous populations and highlighted the need for iterative genotyping at multiple loci to explore the genetic makeup of the isolates. The C. jejuni and C. coli isolates (n=96) obtained from cattle, sheep and water in the third study were subtyped to determine their genetic diversity and zoonotic potential using a modified, novel multi-locus sequence typing method (“massMLST”; Chapter 5). Primers were developed and optimised, PCR-based target-MLST alleles’ amplification were performed, followed by next generation sequencing on an Illumina MiSeq machine. A bioinformatics pipeline of the sequencing data was developed to define C. jejuni and C. coli multi-locus sequence types. This study demonstrated the utility and potential of this novel typing method, massMLST, as a strain typing method. In addition to identifying the possible C. jejuni/coli clonal complexes or sequence types of 68/96 isolates from ruminant faeces and water samples, this study reported three new C. jejuni strains in cattle in New Zealand, along with many strains, such as CC-61, CC-828 and CC-21, that have also been found in humans, indicating the public health significance of these isolates circulating on the farms in the two water catchment areas. Automation of the massMLST method and may allow a cost-effective high-resolution typing method in the near future for multilocus sequence typing of large collections of Campylobacter strains. In the final study (Chapter 6), a pilot metagenomic study was carried out to obtain a snapshot of the microbial ecology of surface water used in the two rural towns of New Zealand for drinking purposes, and to identify the zoonotic pathogens related to waterborne diseases. Fresh samples collected in 2011 and 2012, samples from the same time that were frozen, and samples that were kept in the preservative RNAlater were sequenced using whole-genome shotgun sequencing on an Illumina MiSeq machine. Proteobacteria was detected in all the samples characterised, although there were differences in the genus and species between the samples. The microbial diversity reported varied between the grab and stomacher methods, between samples collected in the year 2011 and 2012, and among the fresh, frozen and RNAlater preserved samples. This study also determined the presence of DNA of potentially zoonotic pathogens such as Cryptosporidium, Campylobacter and Mycobacterium spp. in water. Use of metagenomics could potentially be used to monitor the ecology of drinking water sources so that effective water treatment plans can be formulated, and for reducing the risk of waterborne zoonosis. As a whole, this PhD project provides new data on G. duodenalis assemblages in cattle, sheep and surface water, new information on mixed Cryptosporidium infections in calves, a novel “massMLST” method to subtype Campylobacter species, and shows the utility of shotgun metagenomic sequencing for drinking water monitoring. Results indicate that ruminants (cattle and sheep) in New Zealand shed potentially zoonotic pathogens in the environment and may contribute to the contamination of surface water. A better understanding of waterborne zoonotic transmission would help in devising appropriate control strategies, which could reduce the shedding of Campylobacter, Cryptosporidium, and Giardia spp. in the environment and thereby reduce waterborne transmission.Item A mineralogical and textural study of the central North Island tephra, Okareka ash and its overlying tephric loess deposits : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Soil Science at Massey University(Massey University, 1982) Benny, Lynette AIn Central North Island, New Zealand, Post-Okareka tephric loess rests upon Okareka Ash (c.17,000 years B.P.). Tephric loess accumulation occurred under semiarid conditions which coincided with glacial advances in southern areas of New Zealand. Morphological and grain-size evidence indicates the tephric loess has been derived from a localised source, most probably that of Okareka Ash material, reworked and redeposited by aeolian processes. Optical and electron optical evidence reveals that Okareka Ash particles are angular and relatively unweathered, whereas tephric loess grains are subangular and more weathered. The sand and clay mineralogy of the tephra and tephric loess are similar. Sand fractions contain mainly rhyolitic volcanic glass, quartz, plagioclase feldspar, biotite, hypersthene, hornblende, titanomagnetite and traces of cristobalite, tridymite and augite, whereas clay fractions contain halloysite, allophane, imogolite and gibbsite in varying amounts. Grain-size analysis reveals Okareka Ash deposits show decreasing mean grain-size with increasing distance from source, are poorly-sorted, fine-skewed, and lepto/platykurtic. In contrast to tephra, tephric loess samples exhibit a narrow mean grain-size range, and are better sorted, but show similar skewness and kurtosis values to ash. Grain-size results also indicate that due to minimal weathering of Okareka Ash and Post-Okareka loess, the distinction between the two deposits is less well-defined than data from similar deposits reported by Fisher (1966). Furthermore, where ash deposits are thin, in distal areas from source, and under certain environmental conditions, textural and morphological characteristics of the tephra are similar to those of the tephric loess. Nevertheless, grain-size parameters may be used to differentiate airfall tephra and tephric loess deposits, although this differentiation is enhanced by post-depositional weathering. The contrasting clay mineralogies of tephra and tephric loess samples from sections of similar topography, altitude, drainage and rainfall, illustrates the problems of field sampling in weathering studies.Item Some aranuian (postglacial) organic deposits in the south eastern Ruahine Range, North Island, New Zealand, investigated by palynological methods : a thesis presented in partial fulfilment of the requirements for the Degree of Master of Science in Geography at Massey University(Massey University, 1981) Lees, Cynthia MPalynological methods have been used to investigate Aranuian organic deposits in the south eastern Ruahine Range. The relevant literature was reviewed. Six profiles from five sites ranging in altitude from 80 to 1050 metres and from 13,300 years B.P. to present were sampled and the pollen analysed. Investigation of the palaeoecology of each site included the geomorphology, stratigraphy, present vegetation and pollen rain where relevant. The pollen data as percentages of several pollen sums was presented in pollen diagrams, statistically analysed and an interpretation suggested. An investigation of pollen rain in the Kahuterawa Valley in the Tararua Range and on Mount Ruapehu was made to obtain information on present podocarp-broadleaf forests and about Weinmannia racemosa in particular. The results indicated a succession of dominants, including W. racemosa over a period of up to 1000 years. This information was used in interpreting the pollen spectra of the fossil sites. All sites were reviewed as part of an Aranuian series. It was concluded that a climatic change from a drier cooler climate to a warmer moister one occurred between 13,300 ± and 10,650 (provisional date only). A more equable climate than at present possibly occurred between 3200 ± and 3770 ± with fewer frosts and droughts.These findings are in general agreement with those of palynologists at sites in other parts of New Zealand. Other aspects of climatic change erosional history, plant-land relationships and species representation have been discussed. The decline of W. racemosa at the West Tamaki site was part of a natural stage in the life cycle and not caused by the browsing of the opossum.Item Isolating students with mathematical learning difficulties for teaching purposes : the New Zealand experiences : a thesis presented in partial fulfilment of the requirements for the degree of Master of Education at Massey University(Massey University, 2003) Siber, Elizabeth MaryA survey, by questionnaire, was carried out in seventeen school districts in three regions of North Island, New Zealand, to collect data on the extent of ability grouping for mathematics classes and the experiences of students in mathematics classes. Quantitative data were collected on schools' rationales for or against grouping, selection processes and the teaching programmes used for the lowest achieving students. Qualitative data were collected with respect to teachers' opinions about teaching the lowest achieving students and about the possible reasons for those students' low achievements. The responses from Heads of Mathematics Departments indicate keen interest in best practice for low achieving students. A surprising 99% of respondents reveal that some form of ability grouping for mathematics is implemented in their schools. It is clear that ability grouping is seen as the best approach to meeting the learning needs of all students, whatever their level of achievement. These results incorporated a wide range of schools including all year levels, state and private, large and small and all decile ratings from 1 – 10. Consensus on ability grouping within the wide range of schools in the three geographical regions suggests that schools throughout New Zealand also consider ability grouping as best practice for their low achieving students. The research raises concerns about student self-esteem, motivation and maths anxiety. The need to address those issues as well as mathematical teaching and learning issues is imperative.Item Taking the plunge : assessing and managing risks in adventure tourism in the lower North Island, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Resource and Environmental PLanning at Massey University(Massey University, 1998) Caine, Cheyenne YakimaThis thesis seeks to discover the nature of risks in adventure tourism and how these risks can be managed effectively. There are three major sources of risk i.e. the natural environment, people and equipment. Risk results in consequences. These are usually undesirable events such as drownings. Several incidents have occurred in the recent past prompting negative publicity. To keep incidents at a minimum, several regulatory measures exist for example codes of practice, insurance, risk management plans, legislation, certification and safety standards. These methods can be administered by government, the industry or by businesses themselves. Currently, a combination of the latter two modes of implementation (i.e. industry driven self-regulation) is preferred. A Lower North Island case study using three actives (i.e. whitewater rafting, bungy jumping and jetboating) is used to examine the topic. Operator perceptions of risk are examined, management practices identified and a package for risk management developed. An estimation of the riskiness of the three case study activities is also possible. All businesses interviewed have some form of risk management in place. Operators desire a three tier division of responsibility for risk management including themselves, the government and an industry body.Item Hybridization in North Island tree weta : a thesis submitted in fulfilment of the requirement for the degree of Master of Science in Zoology, Massey University, March 2014(Massey University, 2014) Mckean, NatashaHybridization has important implications for species concepts, understanding the speciation process, as well as the issue of sister species coexistence and conservation. Tree weta (genus Hemideina) are an interesting natural system for studying hybridization, as some species have multiple chromosome races that can interbreed, and all are broadly parapatric with at least one other species in the wild, so there are many opportunities for natural hybridization to occur. It is not known in many cases whether species pairs are hybridizing in the wild, or whether introgression occurs. This study focused on the interactions between H. thoracica and its two neighbouring species; H. crassidens and H. trewicki. Surveys of one area of sympatry between H. thoracica and H. crassidens, and one between H. thoracica and H. trewicki, were conducted to see if the parent species and putative hybrids could be easily distinguished, and to find out the relative ratios of the parents and putative hybrid individuals. Weta from the parent populations were studied in areas where they are sympatric as well as allopatric to look for evidence of possible divergence and/or introgression in sympatry. These studies showed that where these species pairs are sympatric, parent forms were predominant, with few morphological intermediates, despite parent species existing in similar proportions. Hemideina thoracica and H. trewicki differed in sympatry regarding both size and possibly life history, with H. thoracica females being larger and both sexes maturing later than H. trewicki. Hemideina thoracica and H. crassidens showed possible evidence of introgression, but no evidence of divergence in sympatry. Karyotypes, a mitochondrial locus, and eight nuclear loci were examined for evidence of introgression between the species pairs in sympatry. All putative hybrids (morphological intermediates) from both species pairs were found to be genetic hybrids, with strong evidence of being F1 hybrids. No evidence was found for introgression of karyotypes or of mitochondrial haplotypes in either case. No evidence of introgression was found at nuclear loci for H. thoracica and H. trewicki. However, H. thoracica and H. crassidens showed some overlap at nuclear markers in sympatry, suggesting a low level of introgression. There was also a sex-bias in the production of F1 hybrids, with most having a H. crassidens mother. Hemideina thoracica appears to interact differently with its two neighbouring species; H. crassidens and H. trewicki. Hemideina thoracica and H. trewicki appear to be reproductively isolated, and are possibly exploiting different niches. Hemideina thoracica and H. crassidens by contrast, showed no evidence of divergence and are presumably dealing with strong interspecific competition, as well as introgression where they meet. These two species are unusual in maintaining a bimodal hybrid zone in the apparent absence of assortative mating. They also contrast with Haldane’s rule, as F1 males have some level of fertility, while females are likely infertile. A sex-bias in the production of F1 hybrids may be due to ‘sexual exclusion’, and so could possibly provide an explanation of how H. thoracica has managed to displace H. crassidens from much of its former range.Item Some farm management implications of export hogget production on lower North Island hill country sheep farms : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Farm Management at Massey University(Massey University, 1984) Walker, Alan BellThe purpose of this project was to investigate some of the farm management implications of export hogget production on lower North Island Hill country farms from the perspective of a Farm Advisory Officer (Economics) operating within the Advisory Services Division (ASD) of the New Zealand Ministry of Agriculture and Fisheries (MAF). To establish the context in which the study is set, a brief review of the responsibilities of the Economics Section of ASD is presented as a precursor to developing the institutional and industry requirements of farm management research performed by staff of the Economics Section of ASD. Brief reviews of existing sheep meat production systems, management systems for producing lean meat, and the market requirements for export hogget, indicate limited potential for further expansion of hogget production for export under conditions of relative profitability. Simple feed budgeting/gross margins analysis procedures are used to synthesise and evaluate export hogget production strategies for a range of lower North Island hill country farm types. Schedule prices, for export hogget meat, sufficient to break-even with pre export hogget production strategies are established, and the sensitivity of these break-even schedule prices to a range of management, output, and product price variables is investigated. A highlight of the research approach is an interactive component of the research process, developed from Kelly's (1965) Personal Construct Theory and Woog's (1982) Personal Interaction Model of Extension, in which previously developed models are used as a basis for interactive discussions with farmers. Export hogget production is shown to be feasible, although not necessarily fully compatible with, or desirable under, all existing hill country sheep production systems investigated. Export hogget production appears to have greatest potential appeal to moderately intensive farming systems practised under conditions where summer pasture production is poor, relative to winter grass growth. The over-riding conclusion is that, whilst hogget production may have merit as a means of producing larger, leaner, carcases for export, and whilst current production systems appear capable of producing limited amounts of export hogget, current schedule payments preclude any rational decision to produce hogget for export.