Livestock feed intake assumptions in decision support tools; A stocktake of the current science and assumptions used by livestock models

Abstract

<jats:p>Decision Support Tools (DSTs) and models are becoming increasingly important to make informed decisions. The aim of this review was to understand how the scientific assumptions behind related pasture-based DSTs used in New Zealand interrelate. Using modelled feed intake of grazing sheep as a case study, we reviewed the metabolisable energy (ME) assumptions of relevant New Zealand models. Although the DSTs were largely dependent on a common model, there were some discrepancies between them. We raise two concerns: 1. In New Zealand, pasture-based livestock models to predict ME intake are highly dependent on equations developed in Australia, not validated in New Zealand. 2. The minor discrepancies between models make collaboration difficult - this is particularly pertinent to farmer-targeted DSTs. Closer collaboration between DST companies and research institutions is required to agree on consistent, robust equations aligned with the latest scientific knowledge.</jats:p>

Evolution in Configuration and Productivity of New Zealand Hill Country Sheep and Beef Cattle Systems

“…FAR-MAX was originally launched as STOCKPOL, following some years of development [59]. Since rebranding as FARMAX, there has been ongoing development [4], and FARMAX is currently used by many New Zealand sheep and beef cattle producers and professional consultants to adjust production system configuration for improved profitability, and it is also used as a research tool where an estimation of system productivity is required to fulfill research objectives [60]. The agreement of the self-built model and FARMAX in this study to within 1% for the calculation of annual feed demand is probably as close as could ever be achieved by two independent grazing systems models, and it is better than the 5% reported by [9] when output from a similar self-built MEB model in Excel was compared with that from the widely used fertilizer management model Overseer™, which has animal MEB equations built into the nutrient balance calculations and can output the herbage consumption of animals in the system [61].…”

“…In southeast Australia and New Zealand, animal production is largely from pasture-based systems where comparatively little feed is imported and producers do not receive government subsidies. In this context, MEB is used by land holders and their professional advisors for computer simulation of the systems to optimize the product generated from the feed that can be naturally grown on each property [4,5]. By contrast, in the UK, owners receive comparatively large subsidies in return for managing their grazing lands in an environmentally sensitive way and the provision of ecosystem services such as hiking access to the wider public.…”