SUMMARYAn agro-economic simulation model was developed to facilitate comparison of the impact of management, market and biological factors on the cost of providing ruminant livestock with feed grown on the farm (home produced feed). Unpredictable year-to-year variation in crop yields and input prices were identified as quantifiable measures of risk affecting feed cost. Stochastic analysis was used to study the impact of yield and input price risk on the variability of feed cost for eight feeds grown in Ireland over a 10-year period. Intensively grazed perennial ryegrass was found to be the lowest cost feed in the current analysis (mean cost E74/1000 Unité Fourragère Viande (UFV)). Yield risk was identified as the greatest single factor affecting feed cost variability. At mean prices and yields, purchased rolled barley was found to be 3% less costly than home-produced spring-sown barley. However, home-produced spring barley was marginally less risky than purchased barley (coefficient of variation (CV) 0·063 v. 0·064). Feed crops incurring the greatest proportion of fixed costs and area-dependent variable costs, including bunker grass silage, were the most sensitive to yield fluctuations. The most energy inputintensive feed crops, such as grass silage, both baled and bunker ensiled, were deemed most susceptible to input price fluctuations. Maize silage was the most risky feed crop (CV 0·195), with potential to be both the cheapest and the most expensive conserved feed.

The Grange Feed Costing Model was modified to simulate the economic implications of grassland management strategies for a grass-based suckler beef calf-toweanling system at the whole-farm level. The modified model enabled costing of annual grass consumed as grazed grass and silage when the farm grazing and conservation areas are integrated. Grass growth data from sites in the south, east and north of Ireland were used. Sixty-three scenarios were simulated, enabling analysis of site, stocking rate and silage strategy effects on total annual feed cost for the grass forage production system. Total annual feed cost (of grazed grass and grass silage) ranged from €96 to €111 per 1000 UFL (Unité Fourragè re Lait) and €411 to €456 per beef cow unit (CU). The silage strategy with respect to the number of harvests and whether the silage area was grazed in the spring had negligible impact on annual total feed cost per CU. However, a tendency towards reduced annual feed cost under a two harvest, relative to a one harvest, silage strategy was observed. The lowest cost stocking rate was 2 CU ha )1 . Site-specific differences such as seasonal growth distribution and nitrogen fertilizer response rate had the greatest influence on the annual cost of the grass-based feeding system.

Data envelopment analysis (DEA) was employed to develop a model of income and scale efficiency for Irish beef farms. The objective was to identify and quantify management, farm structural and intensity indicators of efficiency for over 400 representative farms over two production systems and two years. Bootstrapping techniques were employed to measure and correct efficiency scores for sampling bias. Less than 10% of the sample exhibited constant or increasing returns to scale. The remaining farms exhibited decreasing returns to scale meaning that they were larger than optimal scale. Greater income efficiency was associated with lower levels of concentrate feeding and lower overhead costs per livestock unit (LU). Fragmentation, paid labour and capital investment were significantly negatively associated with income efficiency. There was a positive relationship between market gross output per LU and income efficiency. Negative market net margins tended to be subsidised by greater off-farm income on smaller (more scale efficient) farms and by greater direct payments on larger (more scale inefficient) farms. Consequently, prospects for increasing beef output via scale expansion are negative in an external environment of declining subsidies and reduced off-farm employment in rural areas. Increased output from Irish beef farms must therefore come primarily from farm system structural changes rather than scale changes, otherwise farm income efficiency will decline.

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