New Zealand hill country sheep and beef farms contain land of various slope classes. The steepest slopes have the lowest pasture productivity and livestock carrying capacity and are the most vulnerable to soil mass movements. A potential management option for these areas of a farm is the planting of native shrubs which are browsable and provide erosion control, biodiversity, and a source of carbon credits. A bioeconomic whole farm model was developed by adding a native shrub sub-model to an existing hill country sheep and beef enterprise model to assess the impacts on feed supply, flock dynamics, and farm economics of converting 10% (56.4 hectares) of the entire farm, focusing on the steep slope areas, to native shrubs over a 50-year period. Two native shrub planting rates of 10% and 20% per year of the allocated area were compared to the status quo of no (0%) native shrub plantings. Mean annual feed supply dropped by 6.6% and 7.1% causing a reduction in flock size by 10.9% and 11.6% for the 10% and 20% planting rates, respectively, relative to 0% native shrub over the 50 years. Native shrub expenses exceeded carbon income for both planting rates and, together with reduced income from sheep flock, resulted in lower mean annual discounted total sheep enterprise cash operating surplus for the 10% (New Zealand Dollar (NZD) 20,522) and 20% (NZD 19,532) planting scenarios compared to 0% native shrubs (NZD 22,270). All planting scenarios had positive Net Present Value (NPV) and was highest for the 0% native shrubs compared to planting rates. Break-even carbon price was higher than the modelled carbon price (NZD 32/ New Zealand Emission Unit (NZU)) for both planting rates. Combined, this data indicates planting native shrubs on 10% of the farm at the modelled planting rates and carbon price would result in a reduction in farm sheep enterprise income. It can be concluded from the study that a higher carbon price above the break-even can make native shrubs attractive in the farming system.

Purpose: Social Life Cycle Assessment (S-LCA) is a tool used to evaluate the social sustainability of products and systems. The performance reference scale is the commonly used S-LCA approach for agricultural systems but has limitations including reliance on social performance assessments, lack of sector-specific value-added activity variables, and dependence on linear reference scoring. These limitations can lead to inaccurate assessments of social issues. We aimed to develop a methodology for the pork value chain and agricultural systems to overcome these shortcomings. Methods: Performance reference points were sourced from national and regional pig industry benchmarks, while generic data was used for inventory indicators. Social performance was expressed using ordinal scores which were converted to cardinal scores based on expert judgments. Social performance was converted to social risks using reversed min–max normalization. The “people” activity variable was enhanced by incorporating population and pig densities with pig per capita used to distinguish the local community from society. Social risks were aggregated with social issue weights and activity variables to calculate social risk time, which culminated in the estimation of social hotspot indices. These enhancements were compared using linear and nonlinear scoring methods. Results and discussion: Average social risks were highest for pigs (0.57 vs. 0.64) and lowest for society (0.47 vs. 0.44) for linear and nonlinear methods, respectively. The distribution and ranking of social risk time for social issues varied between the scoring methods across all stakeholder groups. Both linear and nonlinear methods identified pig farm as a social risk hotspot (0.57 vs. 0.65) and the consumption value chain stage as a social opportunity hotspot (0.39 vs. 0.31). The linear scoring method showed a lack of granularity and systematic bias in estimating the social risks, while the nonlinear method was more nuanced due to incorporating contextualization into the reference scores. Conclusion: The proposed methodology highlighted the importance of including social risks and hotspots, alongside social performance, for an agricultural system S-LCA. It demonstrated the advantages of nonlinear scoring over the linear method, overcoming limitations like lack of granularity and systemic bias in the assessment of social issues. However, a limitation of the nonlinear method lies in potential bias when selecting experts for social issue contextualization. This can be mitigated by carefully selecting stakeholder representatives and conducting a sensitivity analysis.

Information on the nutritive value and in vitro fermentation characteristics of native shrubs in New Zealand is scant. This is despite their potential as alternatives to exotic trees and shrubs for supplementary fodder, and their mitigation of greenhouse gases and soil erosion on hill-country sheep and beef farms. The objectives of this study were to measure the in vitro fermentation gas production, predict the parameters of the in vitro fermentation kinetics, and estimate the in vitro fermentation of volatile fatty acids (VFA), microbial biomass (MBM), and greenhouse gases of four native shrubs (Coprosma robusta, Griselinia littoralis, Hoheria populnea, and Pittosporum crassifolium) and an exotic fodder tree species, Salix schwerinii. The total in vitro gas production was higher (p < 0.05) for the natives than for the S. schwerinii. A prediction using the single-pool model resulted in biologically incorrect negative in vitro total gas production from the immediately soluble fraction of the native shrubs. However, the dual pool model better predicted the in vitro total gas production and was in alignment with the measured in vitro fermentation end products. The in vitro VFA and greenhouse gas production from the fermentation of leaf and stem material was higher (p < 0.05), and the MBM lower (p < 0.05), for the native shrubs compared to the S. schwerinii. The lower in vitro total gas production, VFA, and greenhouse gases production and higher MBM of the S. schwerinii may be explained by the presence of condensed tannins (CT), although this was not measured and requires further study. In conclusion, the results from this study suggest that when consumed by ruminant livestock, browsable native shrubs can provide adequate energy and microbial protein, and that greenhouse-gas production from these species is within the ranges reported for typical New Zealand pastures.

The overreliance on soybeans in broiler diets is unsustainable, driving interest in alternative proteins. However, most studies assess either performance or environmental impacts, limiting holistic assessment. We combined systematic review, meta-analysis and life cycle assessment (LCA) to evaluate circular bioeconomy-derived alternative proteins. The study involved 102 studies from the past 20 years. Alternative proteins were grouped into eight categories: aquatic, dried distillers' grains with solubles (DDGS), seed, leaf, microbial, processed animal proteins (PAPs), rapeseed and mixed proteins. Broiler strains were grouped as Cobb, Ross or "Other". Performance indicators (ADFI, ADG, Feed Conversion Ratio (FCR), digestibility and mortality) were analysed against protein type (PT), inclusion level (L) and strain (S) using mixed-effects and linear models with region as a random factor. For LCA, three top-performing alternatives proteins at two inclusion levels were compared with soybean diets across Ross 308 growth phases. Environmental impacts were quantified within broiler farm system boundary, using a functional unit of 1,000 kg carcass. PAPs use dominated in Europe (44%) and Asia (33%), DDGS in Americas (50%) and seed in Africa (56%). ADFI, ADG, and FCR showed a three-way interaction in starters (PT x L x S, p <0.05), ADG and FCR in growers, and none in finishers, suggesting a declining sensitivity to dietary substitution with age. Ross birds were most sensitive to PT and L (p < 0.05). Ileal DM and CP digestibility decreased (p < 0.05) at higher inclusion for all alternatives. Mortality varied by PT, with seed lower (p < 0.05) than DDGS and microbial proteins. Based on inverse variance-weighted relative FCR, microalgae, PAPs and DDGS were selected for LCA. Microalgae increased all environmental impacts except terrestrial acidification (-15.8%) and marine eutrophication (-22.6%). PAPs reduced all impacts but increased terrestrial acidification (8%). DDGS reduced all impacts per functional unit but increased all impacts in manure except global warming (-4%). No alternative protein fits all contexts and choices must balance broiler performance with environmental sustainability.