By improving grassland management practices the quality and availability of grazed grass can be increased substantially.

Getting horses to eat more grass throughout the year can reduce feed costs especially in the shoulder periods of the year. Other benefits are decreasing the housing periods at certain parts of the year.

Due to the influences of climate the grass growing season starts earliest in the south-west of the country and latest in the north-east. But the highest grass producing farms may not necessarily be in the south.

The total amount of grass grown in Ireland ranges from seven to 16 t DM/ha. Higher levels of production can be achieved on more productive paddocks that are well managed (well fertilised and kept weed free) and reseeded regularly (i.e. every 8-10 years). The most important aspect of grazing management is having the farm set up with a set of defined paddocks and being able to manage a grazing rotation within this infrastructure.

GRAZING DIVISIONS

Grass needs to be managed well if the objective is to have animals thriving. Overgrazing or having exceptionally poor quality pastures (non ryegrass pastures) will only lead to poor animal performance and most likely continued supplementation across the grazing season.

If grass is going to be controlled and utilised well on farms, there needs to be a number of grazing divisions (paddocks) on the farm. This depends on the acreage of the farm, the number of stock on it and number of grazing groups.

For simplicity four grazing divisions (with a residency of 5-7 days) will set up a rotation. Paddock grazing works easily on the principle of ‘graze and rest’. Once a paddock is grazed it is allowed to undergo a rest period to rejuvenate the sward for the following rotation.

Grazing swards with fast rotations or continuous grazing (e.g. 10-14 days) will lower grass production on the farm and place the farm at a greater risk of running into grass deficits.

Some recent research work would show that continually grazing paddocks at 14 day intervals will reduce grass DM production by up to 30% over the total season.

It is important to consider if the composition of the grass in a given paddock will maximise the productivity and quality available for the grazing. Botanical composition tends to reflect previous management (or mismanagement), soil fertility and drainage. Permanent perennial ryegrass dominant paddocks are invariably in fertile situations and on most farms newly reseeded paddocks tend to receive relatively high inputs of fertilisers or other manures to sustain their productivity.

Perennial ryegrass is by far the most productive grass in this climate, if paddocks appear to be unproductive or have a high proportion of non-perennial ryegrass species consideration should be given to reseeding such paddocks.

To ensure that paddocks are productive and remain perennial ryegrass dominant a nitrogen fertilisation programme should be put in place. The first application of nitrogen should be applied in early spring to ensure that grass growth is kick started.

Regular top-ups or applications of nitrogen or nitrogen with P and K compounds should be applied during the year to ensure that sufficient grass is grown and a high level of quality is maintained.

Undergrazing can be an issue with horses due to their selective grazing patterns, the most practical way of getting over this is to mix graze with other livestock, or graze horses in front of cattle or sheep. Continually topping pastures means that the grazing stocking rate is too low.

In recent years, leaving poorly grazed paddocks grow on and conserving them as round bale silage has led to a reduction in the requirement for topping on many livestock farms. Overgrazed paddocks (paddocks grazed to low post-grazing height) may need to be rested for extra time periods, to allow them recover properly.

However, continually overgrazing paddocks will lead to perennial ryegrass becoming compromised and lead to the invasion of weed grasses and weed species. Overgrazing needs to be avoided if possible.

Michael O’Donovan is based at the Grassland Science Research Department, Animal & Grassland Research and Innovation Centre, Teagasc Moorepark, Fermoy, Co Cork