Browsing IJAFR volume 50, no. 1, 2011 (Special Issue) by Author "O'Donovan, Michael"
Capturing the economic benefit of Lolium perenne cultivar performanceMcEvoy, Mary; O'Donovan, Michael; Shalloo, Laurence; Department of Agriculture, Food and the Marine (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)Economic values were calculated for grass traits of economic importance in Irish grass-based ruminant production systems. Traits considered were those that had the greatest potential to influence the profitability of a grazing system. These were: grass dry matter (DM) yield in spring, mid-season and autumn, grass quality (dry matter digestibility; DMD), 1st and 2nd cut silage DM yield and sward persistency. The Moorepark Dairy Systems Model was used to simulate a dairy farm. Economic values were calculated by simulating the effect of a unit change in the trait of interest while holding all other traits constant. The base scenario involved a fixed herd size and land area (40 ha), and an annual DM yield of 13 t/ha. The economic values generated under the base scenario were: € 0.152/kg for DM yield in spring, € 0.030/kg for DM yield in mid-season and € 0.103/kg for DM yield in autumn; € 0.001, € 0.008, € 0.010, € 0.009, € 0.008 and € 0.006 per 1 g/kg change in DMD for the months of April to September, respectively; € 0.03/kg for 1st cut silage DM yield, € 0.02/kg for 2nd cut silage DM yield; and − € 4.961 for a 1 percent reduction in persistency. Alternative scenarios were examined to determine the sensitivity of the economic values to changes in annual DM yield, sward utilisation and a scenario where silage production was the focus of the system. The economic values were used to calculate a total merit index for each of 20 perennial ryegrass cultivars based on production data from a 3 year plot study. The rank correlation between the merit index values for the cultivars under the base scenario and the scenario involving a reduction in herbage utilisation was 1.0, while that with the scenario involving reduced annual DM yield was 0.94. It is concluded that the total merit index can be used to identify cultivars that can generate the greatest economic contribution to a grass-based production system, regardless of system or intensity of grass production.
The economics of reseeding on a dairy farmShalloo, Laurence; Creighton, Philip; O'Donovan, Michael (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)Herbage production and utilization on Irish dairy farms is well below its potential. A number of factors influence herbage production and utilization, not least the level of annual reseeding (introduction of a new grass ley) on the farm. The potential farm performance is reduced by old permanent pasture due to the combined effects of reduced out-of-season herbage production and lower overall herbage yield when compared to perennial ryegrass. Based on the sales of grass seed, it is estimated that approximately 2% of the land area on dairy farms in Ireland is reseeded annually. This has created a situation where the overall percentage of perennial ryegrass in sward is low. The objective of the present study was to investigate the economic benefits of reseeding through simulating the consequences of reseeding different proportions of the farm on an annual basis. Four levels of an annual reseeding programme were evaluated: 1%, 5%, 10% and 15% of the farm reseeded annually; evaluated at three milk prices (20 c/L, 27c/L and 33 c/L). Increasing the level of reseeding resulted in an increase in total and seasonal herbage production and, when accompanied by an increased stocking rate, increased herbage utilization. At a milk price of 27 c/L, farm profitability was €20 764, €24 794, €30 073 and €33 515 on a 40 ha farm when 1%, 5%, 10% and 15%, respectively, of the farm was reseeded annually. Irrespective of milk price, increasing the level of reseeding had a positive effect on profitability and the highest gain was achieved at the highest milk price. Sensitivity analysis showed that sward persistency and, to a lesser extent, herbage utilization had significant effects on the benefit from reseeding.
Requirements of future grass-based ruminant production systems in IrelandO'Donovan, Michael; Lewis, Eva; O'Kiely, Padraig (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)There is a renewed interest in grazing systems in many temperate and subtropical regions of the world. This results from lower inflation-adjusted prices, the proposed removal of some subsidies and tariffs, and rising labour, machinery and housing costs. The utilization of grass by grazing should provide the basis of sustainable livestock systems as grazed grass is the cheapest source of nutrients for ruminants. This is very important in the Irish context as there are approximately 130 000 farmers involved in primary production in Ireland and the value of the goods produced was €5.8 billion in 2008. For the future, the key objective for grazing systems is to ensure high grass utilization, allowing increased output per hectare for all sectors. The primary emphasis in grass breeding needs to be focused on (i) seasonal growth pattern as well as overall annual growth, (ii) nutritive value, including digestibility, particularly in the mid-season period, (iii) ensuring a sward canopy structure that is suitable for grazing, and (iv) development of persistent cultivars that perform under farm conditions. Evaluation programmes should also consider including an estimate of production potential at the field as well as at plot level, and evaluation under grazing management systems as well as under mixed grazing/silage management systems. It is difficult to accurately quantify the breeding achievements for grass mainly because its value, whether grazed or conserved, must be indirectly realised through the output of animal product. Grass evaluation and breeding need to better accommodate the requirements of the grazing ruminant. This will necessitate the application of new approaches and knowledge, which will ultimately enable further increases in animal output per hectare to be achieved.