Increasing animal performance from grass

There has been an increased focus on improving grassland management and utilisation in the Republic of Ireland in recent years, where the collation of on farm production data has led to major advances in grass production.

The Irish agriculture and food development authority, Teagasc, has been working in conjunction with the Department of Agriculture, Food and the Marine (DAFM) to create a Pasture Profit Index (PPI) which aims to help farmers in their selection of grass varieties.  The index was developed in response to Irish farmers’ increased interest in individual grass varieties and demand for some form of economic evaluation.

Dr Mary McEvoy of Germinal Ireland was part of the Teagasc Moorepark team which developed the PPI.  Dr McEvoy recently addressed Morton’s staff and demonstrated that the index is a valuable tool which is very much applicable to farmers in Northern Ireland. Indeed, farmers should make use of all the information available to them when deciding on the best varieties for their farm – the N.I. DARD Recommended List, the DAFM Recommended List and the Irish PPI, as well as the Recommended Grass and Clover Lists for England and Wales.

The PPI assigns an economic value to traits of grass varieties – these include seasonal dry matter yield, quality, silage dry matter yield and persistency. Germinal varieties AberGain, AberChoice and AberMagic all rank in the top 4 varieties for quality - a key factor in improving animal performance.  A one percent increase in DMD (Dry Matter Digestibility) leads to a 5% increase in animal performance.  For example – if a cow produces 25 litres per day on a control sward, on 84.4% DMD grass she will potentially yield 27 litres per day. Two litres per cow per day is equivalent to 38p per cow per day. For a herd of 100 cows this equates to £38 per day, or £1140 over 30 days.

Maximising grass percentage in the diet will reduce feed costs through reducing reliance on concentrates.  Increasing grass percentage in the diet will also increase milk protein content and therefore improve farm profitability.  To put this into monetary terms - each additional t/DM/ha utilised on farm is worth around £116/ha.

If we look at the benefits of having extra grass in spring, each additional day at grass can deliver £1.95 per cow per day.  100 cows x £1.95 = £195 for each extra day grazing; £1365 per week.

Extending the grazing season in autumn will also lead to reduced feed costs and increased animal performance.   Each additional day at grass = £1.51 per cow per day. 100 cows X £1.51 = £151 per extra day; £1057 per week. 

For farmers considering when to reseed next year, Dr McEvoy recommends reseeding in spring if possible, but recognises that there are a significant proportion of farmers both North and South that prefer to reseed in autumn.  Figures suggest that the proportion of farmers reseeding in spring in Northern Ireland is roughly equivalent to those reseeding in autumn.  The reason for reseeding in autumn is often due to budgetary considerations, but there can be challenges in the form of dropping soil temperatures and variable weather conditions – which can make grazing difficult, and applying post emergence spray can be problematic.

Reseeding in spring, on the other hand, offers greater flexibility, with improving soil conditions, higher temperatures and longer days.  It allows for several grazings in the early part of the year to ensure a well-tillered sward in autumn, and provides a greater opportunity to apply post-emergence spray.

A post emergence spray is crucial six weeks after sowing.  This provides the best opportunity to control weeds in the new sward.  The most appropriate spray depends on the main weeds present.  If clover is included in grass seed mixture, it is important to remember that the spray must be clover safe.

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