Attitudes and beliefs of argentinian medical oncologists regarding palliative care referral / Actitudes y creencias de los médicos oncólogos argentinos sobre la derivación a cuidados paliativos

Abstract Introduction: Local evidence suggests insufficient access to palliative care (PC) for advanced cancer patients. The objective was to investigate the attitudes and beliefs of Argentinian medical oncologists regarding PC referral of their patients. Methods: All medical oncologists listed in the main national Clinical Oncology Associations (N = 831) were invited to participate in a telephone survey. Results: Fifty nine percent (N = 489) completed the survey. Most reported being informed about the scopes of PC (83%) and having accessible PC service/specialists (71%). However, 53% did not work collaboratively, and 55% exceptionally or never referred their patients. Oncologists who usually referred their patients did so mainly due to uncontrolled pain (67%) or absence of curative treatment (48%). Only 19% supported early-referral criteria. Those who exception ally referred their patients argued that PC was not meaningful/beneficial/a priority (78%) or that they preferred to handle the patient's problems by themselves (55%). End-of-life care (33%) and improvement in quality of life (32%) were stated as primary benefits of PC for cancer patients. Addressing psychological aspects was consid ered the least important item (2%). Having an accessible PC service (P = 0.002) and being well informed about PC (P = 0.008) were associated with frequent referral. Having ≤10 years or >30 years from graduation were associated with exceptional or no referral (P = 0.012 and 0.001, respectively). Discussion: Oncologists report awareness of the potential advantages of PC and have accessible PC services, but rarely refer patients. They mainly use late-referral criteria. Younger and older age are negatively associated with referral. More research is needed to improve the referral rate and timing of cancer patients to PC.

Resumen Introducción: La evidencia local sugiere un acceso insuficiente a los cuidados paliativos (CP) para los pacien tes con cáncer avanzado. El objetivo fue investigar las actitudes y creencias de médicos oncólogos argentinos respecto de la derivación de sus pacientes a CP. Métodos: Todos los médicos oncólogos registrados en las principales Asociaciones Nacionales de Oncología Clínica (N = 831) fueron invitados a participar en una encuesta telefónica. Resultados: El 59% (N = 489) completó la encuesta. La mayoría informó estar informado sobre los alcances de CP (83%) y tener especialistas/servicios de CP acce sibles (71%). Sin embargo, el 53% no trabajaba de forma colaborativa y el 55% excepcionalmente o nunca derivaba a sus pacientes. Los oncólogos que habi tualmente derivan a sus pacientes lo hacen principalmente por dolor no controlado (67%) o ausencia de trata miento curativo (48%). Solo el 19% mencionó criterios de derivación temprana. Aquellos que excepcionalmente derivan a sus pacientes argumentaron que los CP no era significativos, beneficiosos o prioritarios (78%) o que preferían manejar los problemas del paciente por sí mismos (55%). La atención al final de la vida (33 %) y la mejora de la calidad de vida (32 %) se señalaron como los principales beneficios de los CP para los pacientes con cáncer. El abordaje de los aspectos psicológicos fue el ítem menos señalado (2%). Tener un servicio de CP accesible (P= 0,002) y estar bien informado sobre CP (P = 0,008) se asociaron con la derivación frecuente. Tener ≤10 años o >30 años desde la graduación se asoció con una derivación excepcional o nula (P = 0,012 y 0,001, respectivamente). Discusión: Los oncólogos refieren conocer las ventajas potenciales de los CP y tienen servicios de CP accesibles, pero rara vez derivan pacientes. Utilizan principalmente criterios de derivación tardía. Las edades más jóvenes y mayores se asocian negativamente con la derivación. Se necesita más investigación para mejorar la tasa y momento de derivación de los pacientes con cáncer a CP.

Attitudes and beliefs of Argentinian medical oncologists regarding palliative care referral.

INTRODUCTION: Local evidence suggests insufficient access to palliative care (PC) for advanced cancer patients. The objective was to investigate the attitudes and beliefs of Argentinian medical oncologists regarding PC referral of their patients. METHODS: All medical oncologists listed in the main national Clinical Oncology Associations (N = 831) were invited to participate in a telephone survey. RESULTS: Fifty nine percent (N = 489) completed the survey. Most reported being informed about the scopes of PC (83%) and having accessible PC service/specialists (71%). However, 53% did not work collaboratively, and 55% exceptionally or never referred their patients. Oncologists who usually referred their patients did so mainly due to uncontrolled pain (67%) or absence of curative treatment (48%). Only 19% supported early-referral criteria. Those who exceptionally referred their patients argued that PC was not meaningful/beneficial/a priority (78%) or that they preferred to handle the patient's problems by themselves (55%). End-of-life care (33%) and improvement in quality of life (32%) were stated as primary benefits of PC for cancer patients. Addressing psychological aspects was considered the least important item (2%). Having an accessible PC service (P = 0.002) and being well informed about PC (P = 0.008) were associated with frequent referral. Having =10 years or >30 years from graduation were associated with exceptional or no referral (P = 0.012 and 0.001, respectively). DISCUSSION: Oncologists report awareness of the potential advantages of PC and have accessible PC services, but rarely refer patients. They mainly use late-referral criteria. Younger and older age are negatively associated with referral. More research is needed to improve the referral rate and timing of cancer patients to PC.

Introducción: La evidencia local sugiere un acceso insuficiente a los cuidados paliativos (CP) para los pacientes con cáncer avanzado. El objetivo fue investigar las actitudes y creencias de médicos oncólogos argentinos respecto de la derivación de sus pacientes a CP. Métodos: Todos los médicos oncólogos registrados en las principales Asociaciones Nacionales de Oncología Clínica (N = 831) fueron invitados a participar en una encuesta telefónica. Resultados: El 59% (N = 489) completó la encuesta. La mayoría informó estar informado sobre los alcances de CP (83%) y tener especialistas/servicios de CP acce sibles (71%). Sin embargo, el 53% no trabajaba de forma colaborativa y el 55% excepcionalmente o nunca derivaba a sus pacientes. Los oncólogos que habitualmente derivan a sus pacientes lo hacen principalmente por dolor no controlado (67%) o ausencia de tratamiento curativo (48%). Solo el 19% mencionó criterios de derivación temprana. Aquellos que excepcionalmente derivan a sus pacientes argumentaron que los CP no era significativos, beneficiosos o prioritarios (78%) o que preferían manejar los problemas del paciente por sí mismos (55%). La atención al final de la vida (33 %) y la mejora de la calidad de vida (32 %) se señalaron como los principales beneficios de los CP para los pacientes con cáncer. El abordaje de los aspectos psicológicos fue el ítem menos señalado (2%). Tener un servicio de CP accesible (P= 0,002) y estar bien informado sobre CP (P = 0,008) se asociaron con la derivación frecuente. Tener =10 años o >30 años desde la graduación se asoció con una derivación excepcional o nula (P = 0,012 y 0,001, respectivamente). Discusión: Los oncólogos refieren conocer las ventajas potenciales de los CP y tienen servicios de CP accesibles, pero rara vez derivan pacientes. Utilizan principalmente criterios de derivación tardía. Las edades más jóvenes y mayores se asocian negativamente con la derivación. Se necesita más investigación para mejorar la tasa y momento de derivación de los pacientes con cáncer a CP.

Benefits and Trade-Offs of Dairy System Changes Aimed at Reducing Nitrate Leaching.

Between 2011 and 2016, small-scale farm trials were run across three dairy regions of New Zealand (Waikato, Canterbury, Otago) to compare the performance of typical regional farm systems with farm systems implementing a combination of mitigation options most suitable to the region. The trials ran for at least three consecutive years with detailed recording of milk production and input costs. Nitrate leaching per hectare of the milking platform (where lactating cows are kept) was estimated using either measurements (suction cups), models, or soil mineral nitrogen measurements. Post-trial, detailed farm information was used in the New Zealand greenhouse gas inventory methodology to calculate the emissions from all sources; dairy platform, dairy support land used for wintering non-lactating cows (where applicable) and replacement stock, and imported supplements. Nitrate leaching was also estimated for the support land and growing of supplements imported from off-farm using the same methods as for the platform. Operating profit (NZ$/ha/year), nitrate leaching (kg N/ha/year), and greenhouse gas emissions (t CO2-equivalent/ha/year) were all expressed per hectare of milking platform to enable comparisons across regions. Nitrate leaching mitigations adopted in lower-input (less purchased feed and nitrogen fertiliser) farm systems reduced leaching by 22 to 30 per cent, and greenhouse gas emissions by between nine and 24 per cent. The exception was the wintering barn system in Otago, where nitrate leaching was reduced by 45 per cent, but greenhouse gas emissions were unchanged due to greater manure storage and handling. Important drivers of a lower environmental footprint are reducing nitrogen fertiliser and purchased feed. Their effect is to reduce feed flow through the herd and drive down both greenhouse gas emissions and nitrate leaching. Emission reductions in the lower-input systems of Waikato and Canterbury came at an average loss of profit of approximately NZ$100/t CO2-equivalent (three to five per cent of industry-average profit per hectare).

The Effects of System Changes in Grazed Dairy Farmlet Trials on Greenhouse Gas Emissions.

An important challenge facing the New Zealand (NZ) dairy industry is development of production systems that can maintain or increase production and profitability, while reducing impacts on receiving environments including water and air. Using research 'farmlets' in Waikato, Canterbury, and Otago (32⁻200 animals per herd), we assessed if system changes aimed at reducing nitrate leaching can also reduce total greenhouse gas (GHG) emissions (methane and nitrous oxide) and emissions intensity (kg GHG per unit of product) by comparing current and potential 'improved' dairy systems. Annual average GHG emissions for each system were estimated for three or four years using calculations based on the New Zealand Agricultural Inventory Methodology, but included key farmlet-specific emission factors determined from regional experiments. Total annual GHG footprints ranged between 10,800 kg and 20,600 kg CO2e/ha, with emissions strongly related to the amount of feed eaten. Methane (CH4) represented 75% to 84% of the total GHG footprint across all modelled systems, with enteric CH4 from lactating cows grazing pasture being the major source. Excreta deposition onto paddocks was the largest source of nitrous oxide (N2O) emissions, representing 7⁻12% of the total GHG footprint for all systems. When total emissions were represented on an intensity basis, 'improved' systems are predicted to generally result in lower emissions intensity. The 'improved' systems had lower GHG footprints than the 'current' system, except for one of the 'improved' systems in Canterbury, which had a higher stocking rate. The lower feed supplies and associated lower stocking rates of the 'improved' systems were the key drivers of lower total GHG emissions in all three regions. 'Improved' systems designed to reduced N leaching generally also reduced GHG emissions.

Bevacizumab biosimilar BEVZ92 versus reference bevacizumab in combination with FOLFOX or FOLFIRI as first-line treatment for metastatic colorectal cancer: a multicentre, open-label, randomised controlled trial.

BACKGROUND: BEVZ92 is a proposed biosimilar to bevacizumab. The two molecules have similar physicochemical and functional properties in in-vitro and preclinical studies. In this clinical study, we compared the pharmacokinetic profile, efficacy, safety, and immunogenicity of BEVZ92 with reference bevacizumab as a first-line treatment in patients with metastatic colorectal cancer. METHODS: We did a randomised, open-label trial at 15 centres in Argentina, Brazil, India, Spain, and Ukraine. Eligible patients were aged 18 years or older, had metastatic colorectal cancer with at least one measurable non-irradiated lesion for which first-line chemotherapy was indicated and Eastern Cooperative Oncology Group (ECOG) performance status of 2 or less, had not received previous treatment for advanced disease, and whose bone marrow, hepatic, renal, and coagulation markers were all within normal ranges. Patients were randomly assigned (1:1) to either BEVZ92 or reference bevacizumab (5 mg/kg on day 1 of each cycle every 2 weeks) in combination with fluorouracil, leucovorin, and oxaliplatin (FOLFOX) or fluorouracil, leucovorin, and irinotecan (FOLFIRI). Randomisation was done via a web service based on a stochastic minimisation algorithm and was stratified by chemotherapy regimen (FOLFOX vs FOLFIRI), previous adjuvant therapy (yes vs no), ECOG performance status (0-1 vs 2), and study site. The primary endpoint was the area under the concentration-versus-time curve after a single infusion (AUC0-336h) and at steady state (AUCss)-ie, at cycle 7-in the assessable population, which comprised all treated patients for whom serum concentration measurements were available during the first seven cycles. Bioequivalence was established if the 90% CIs for the ratio of BEVZ92 to reference bevacizumab of the geometric means for AUC0-336h and AUCss were within the acceptance interval of 80-125%. Secondary endpoints included objective response, clinical benefit, and progression-free survival in the intention-to-treat population and immunogenicity and safety profiles in all treated patients. This trial is registered with ClinicalTrials.gov, number NCT02069704, and is closed to new participants, with follow-up completed. FINDINGS: 142 patients were randomly assigned, 71 to the BEVZ92 group and 71 to the reference bevacizumab group. Two participants assigned to BEVZ92 did not receive treatment (one withdrew consent, the other had a serious intestinal obstruction before starting treatment); therefore, the treated population comprised 69 patients in the BEVZ92 group and 71 in the reference bevacizumab group. The geometric mean ratio of AUC0-336h in the BEVZ92 versus the control group was 99·4% (90% CI 90·5-109·0) and of AUCss was 100·0% (90·2-112·0). Objective response (35 [49%] of 71 vs 40 [56%] of 71), clinical benefit (62 [87%] vs 65 [92%]), and progression-free survival (median 10·8 months [95% CI 7·4-11·5] vs 11·1 months [95% CI 8·0-12·8]) were similar in the BEVZ92 and reference bevacizumab groups. No relevant differences were noted between the safety profiles of the two study treatments. Neutropenia was the most common grade 3 or 4 adverse event reported in the BEVZ92 (14 [20%] of 69 patients) and reference bevacizumab (19 [27%] of 71 patients) groups. Serious adverse events occurred in 19 (28%) patients in the BEVZ92 group and 21 (30%) in the reference bevacizumab group. Two patients died because of bevacizumab-related serious adverse events: a sudden death in the BEVZ92 group and a serious large intestinal perforation in the reference bevacizumab group. The occurrence of anti-drug antibodies was low and similar in both treatment groups (two patients in the BEVZ92 group and one in the reference bevacizumab group). INTERPRETATION: Our results suggest that BEVZ92 and reference bevacizumab are pharmacokinetically bioequivalent and have no appreciable differences in efficacy, immunogenicity, and safety profiles as first-line treatment in combination with FOLFOX or FOLFIRI in patients with metastatic colorectal cancer. FUNDING: mAbxience Research SL.

Combining field experiments and predictive models to assess potential for increased plant diversity to climate-proof intensive agriculture.

Agricultural production systems face increasing threats from more frequent and extreme weather fluctuations associated with global climate change. While there is mounting evidence that increased plant community diversity can reduce the variability of ecosystem functions (such as primary productivity) in the face of environmental fluctuation, there has been little work testing whether this is true for intensively managed agricultural systems. Using statistical modeling techniques to fit environment-productivity relationships offers an efficient means of leveraging hard-won experimental data to compare the potential variability of different mixtures across a wide range of environmental contexts. We used data from two multiyear field experiments to fit climate-soil-productivity models for two pasture mixtures under intensive grazing-one composed of two drought-sensitive species (standard), and an eight-species mixture including several drought-resistant species (complex). We then used these models to undertake a scoping study estimating the mean and coefficient of variation (CV) of annual productivity for long-term climate data covering all New Zealand on soils with low, medium, or high water-holding capacity. Our results suggest that the complex mixture is likely to have consistently lower CV in productivity, irrespective of soil type or climate regime. Predicted differences in mean annual productivity between mixtures were strongly influenced by soil type and were closely linked to mean annual soil water availability across all soil types. Differences in the CV of productivity were only strongly related to interannual variance in water availability for the lowest water-holding capacity soil. Our results show that there is considerable scope for mixtures including drought-tolerant species to enhance certainty in intensive pastoral systems. This provides justification for investing resources in a large-scale distributed experiment involving many sites under different environmental contexts to confirm these findings.

Combining Restricted Grazing and Nitrification Inhibitors to Reduce Nitrogen Leaching on New Zealand Dairy Farms.

Intensification of pastoral dairy systems often means more nitrogen (N) leaching. A number of mitigation strategies have been proposed to reduce or reverse this trend. The main strategies focus on reducing the urinary N load onto pastures or reducing the rate of nitrification once the urine has been deposited. Restricted grazing is an example of the former and the use of nitrification inhibitors an example of the latter. A relevant concern is the cost effectiveness of these strategies, independently and jointly. To address this concern, we employed a modeling approach to estimate N leaching with and without the use of these mitigation options from a typical grazing dairy farm in New Zealand. Three restricted grazing options were modeled with and without a nitrification inhibitor (dicyandiamide, DCD) and the results were compared with a baseline farm (no restricted grazing, no inhibitor). Applying DCD twice a year, closely following the cows after an autumn and winter grazing round, has the potential to reduce annualized and farm-scale N leaching by ∼12%, whereas restricted grazing had leaching reductions ranging from 23 to 32%, depending on the timing of restricted grazing. Combining the two strategies resulted in leaching reductions of 31 to 40%. The abatement cost per kilogram of N leaching reduction was NZ$50 with DCD, NZ$32 to 37 for restricted grazing, and NZ$40 to 46 when the two were combined. For the range analyzed, all treatments indicated similar cost per percentage unit of mitigated N leaching, demonstrating that restricted grazing and nitrification inhibitors can be effective when used concurrently.

Screening for diets that reduce urinary nitrogen excretion and methane emissions while maintaining or increasing production by dairy cows.

Farmers face complex decisions at the time to feed animals, trying to achieve production goals while contemplating social and environmental constraints. Our purpose was to facilitate such decision making for pastoral dairy farmers, aiming to reduce urinary N (UN) and methane emissions (CH4), while maintaining or increasing milk production (MP). There is a number of feeds the farmers can choose from and combine. We used 50 feeds (forages and grains) combined systematically in different proportions producing 11,526 binary diets. Diets were screened, using an a posteriori approach and a Pareto front (PF) analysis of model (Molly) outputs. The objective was to identify combinations with the best possible compromise (i.e. frontier) between UN, CH4, and MP. Using high MP and low UN as objective functions, PF included 10, 14, 12 and 50 diets, for non-lactating, early-, mid- and late-lactation periods, with cereals and beets featuring strongly. Using the same objective functions, but including ryegrass as dietary base PF included 2, 4, 8 and 4 diets for those periods. Therefore, from a wide range of diets, farmers could choose from few feeds combined into binary diets to reduce UN while maintaining or increasing MP. If the intention is maintaining pasture-based systems, there are fewer suitable options. Reducing UN will simply require dilution of N supplied by pasture by supplementing low N conserved forages. The results also evidence the risk of pollution swapping, reaching the frontier means arriving at a point where trade-off decisions need to be made. Any further reduction in UN implies an increment in CH4, or reduction in CH4 emissions increases UN. There is no perfect diet to optimize all objectives simultaneously; but if the current diet is not in the frontier some options can offset pollution swapping. The choice is with the farmers and conditioned by their context.

Environmental sampling of Ceratonia siliqua (carob) trees in Spain reveals the presence of the rare Cryptococcus gattii genotype AFLP7/VGIV / Muestreos medioambientales de algarrobos ( Ceratonia siliqua) españoles revelan la presencia del raro genotipo AFLP7/VGIV de Cryptococcus gattii

Background. Cryptococcus gattii is a pathogenic basidiomycetous yeast that is emerging in temperate climate zones worldwide. C. gattii has repetitively been isolated from numerous tree species. Ongoing environmental sampling and molecular characterization is essential to understand the presence of this primary pathogenic microorganism in the Mediterranean environment. Aims. To report the first isolation of the rare C. gattii genotype AFLP7/VGIV from the environment in Europe. Methods. Samples were collected from woody debris of carob trees (Ceratonia siliqua) and olive trees (Olea europaea) in El Perelló, Tarragona, Spain. Cryptococcus species were further characterized by using URA5-RFLP, MALDI-TOF, AFLP and MLST. The antifungal susceptibility profile to amphotericin B, 5-fluorocytosine, fluconazole, itraconazole, posaconazole and voriconazole was determined using Sensititre Yeast One and E-test. Results. Cultures from one carob tree revealed the presence of ten Cryptococcus-like colonies. One colony was identified as C. gattii, and subsequent molecular characterization showed that it was an α mating-type that belonged to the rare genotype AFLP7/VGIV. Antifungal susceptibility testing showed values within the range of sensitivity described for other isolates of the same genotype and within the epidemiological cutoff values for this species. Conclusions. The isolation of the rare C. gattii genotype AFLP7/VGIV in Spain is the first report in the European environment, implying the possible presence in other regions of the Mediterranean area, and underlines that clinicians must be aware for C. gattii infections in healthy individuals (AU)

Antecedentes. Cryptococcus gattii es una levadura perteneciente a los basidiomicetos y considerada un patógeno emergente en climas templados. C. gattii se ha aislado en un gran número de especies de árboles en todo el mundo. El muestreo medioambiental y la caracterización molecular de C. gattii es esencial para entender la presencia de este patógeno primario en el entorno de la cuenca mediterránea. Objetivos. Comunicar la presencia del raro genotipo AFLP7/VGIV de C. gattii en el medioambiente en Europa. Métodos. Se tomaron muestras de detritus de algarrobos (Ceratonia siliqua) y olivos (Olea europaea) en las afueras de El Perelló (Tarragona, España). La colonia de C. gattii aislada se sometió a análisis mediante URA5-RFLP, MALDI-TOF, AFLP y MLST. Se llevó a cabo un estudio de sensibilidad in vitro a la anfotericina B, 5-fluorocitosina, fluconazol, itraconazol, posaconazol y voriconazol mediante las pruebas comerciales Sensititre Yeast One® y E-test®. Resultados. De una de las muestras de un algarrobo se aislaron 10 colonias susceptibles de ser Cryptococcus. Una de ellas fue estudiada e identificada como C. gattii, y su subsecuente caracterización molecular mostró que se trataba de un tipo sexual α y que pertenecía al raro genotipo AFLP7/VGIV. El estudio de la sensibilidad a los antifúngicos mostró valores similares a los de otras cepas del mismo genotipo y dentro del rango de valores de corte epidemiológicos para la especie. Conclusiones. El aislamiento en España de C. gattii con el genotipo AFLP7/VGIV es el primero descrito en el medioambiente en Europa; podría encontrarse también en otros países de la cuenca mediterránea, donde debería tenerse un especial cuidado por la posibilidad de infección en individuos no inmunodeprimidos (AU)

Environmental sampling of Ceratonia siliqua (carob) trees in Spain reveals the presence of the rare Cryptococcus gattii genotype AFLP7/VGIV.

BACKGROUND: Cryptococcus gattii is a pathogenic basidiomycetous yeast that is emerging in temperate climate zones worldwide. C. gattii has repetitively been isolated from numerous tree species. Ongoing environmental sampling and molecular characterization is essential to understand the presence of this primary pathogenic microorganism in the Mediterranean environment. AIMS: To report the first isolation of the rare C. gattii genotype AFLP7/VGIV from the environment in Europe. METHODS: Samples were collected from woody debris of carob trees (Ceratonia siliqua) and olive trees (Olea europaea) in El Perelló, Tarragona, Spain. Cryptococcus species were further characterized by using URA5-RFLP, MALDI-TOF, AFLP and MLST. The antifungal susceptibility profile to amphotericin B, 5-fluorocytosine, fluconazole, itraconazole, posaconazole and voriconazole was determined using Sensititre Yeast One and E-test. RESULTS: Cultures from one carob tree revealed the presence of ten Cryptococcus-like colonies. One colony was identified as C. gattii, and subsequent molecular characterization showed that it was an α mating-type that belonged to the rare genotype AFLP7/VGIV. Antifungal susceptibility testing showed values within the range of sensitivity described for other isolates of the same genotype and within the epidemiological cutoff values for this species. CONCLUSIONS: The isolation of the rare C. gattii genotype AFLP7/VGIV in Spain is the first report in the European environment, implying the possible presence in other regions of the Mediterranean area, and underlines that clinicians must be aware for C. gattii infections in healthy individuals.

Cost-effective mitigation of greenhouse gas emissions from different dairy systems in the Waikato region of New Zealand.

The New Zealand dairy industry produces approximately 17% of this country's total greenhouse gas emissions (GHG-e) and it is also this nation's largest export industry. The industry needs to reduce GHG-e under proposed policy directives and for ongoing market security. Given these pressures, there is the need to identify cost-effective management strategies to reduce on-farm GHG-e. The objective of this study was to investigate how the management of dairy farms in the Waikato region of New Zealand could change to minimise the abatement costs associated with GHG-e mitigation. Three typical farm systems importing low (less than 10%), medium (10-20%), and high (more than 20%) amounts of supplement are modelled using a non-linear optimisation model. A reduction in nitrogen fertiliser application was the production factor that changed the most to achieve the cap in all of the simulated systems, followed by a reduction in stocking rate. With the prices used in this study, decreasing farming intensity by reducing nitrogen fertiliser by 21-42% and stocking rate by 8-10% represented a cost of $68-$119/ha and a production reduction of 54-117 kg MS/ha for the three systems studied. Improving reproductive performance proved to be effective in reducing GHG-e, allowing for fewer replacement cows to be supported. However, it did not have a significant effect on profit when emissions were unconstrained. Nitrification inhibitors and stand-off pads were not identified as useful mitigation options, given their high cost relative to de-intensification.

An optimization model of a New Zealand dairy farm.

Optimization models are a key tool for the analysis of emerging policies, prices, and technologies within grazing systems. A detailed, nonlinear optimization model of a New Zealand dairy farming system is described. This framework is notable for its inclusion of pasture residual mass, pasture utilization, and intake regulation as key management decisions. Validation of the model shows that the detailed representation of key biophysical relationships in the model provides an enhanced capacity to provide reasonable predictions outside of calibrated scenarios. Moreover, the flexibility of management plans in the model enhances its stability when faced with significant perturbations. In contrast, the inherent rigidity present in a less-detailed linear programming model is shown to limit its capacity to provide reasonable predictions away from the calibrated baseline. A sample application also demonstrates how the model can be used to identify pragmatic strategies to reduce greenhouse gas emissions.