Grassland management

Grass growth rates and supplies remain variable with some areas of the country getting a good level of rainfall since the start of the week while others received a small amount and are still under pressure. The extent of the grass supply deficit is greatest where a high area of ground was removed as surplus grass or where a good deal of topping was carried out.

Recovery on these paddocks has been slower and is significantly tightening the area available for grazing. The situation will also be slow to change with a significant increase in temperatures forecast. Where grass supplies are tight, weaning and targeting the best grass available to lambs will provide a reprieve with ewes used to graze off stemmy swards or tightened up and supplemented in the short term with hay or silage. In cases of very tight supplies, introducing meal supplementation to lambs will help to underpin performance.

The situation will be considerably different on farms which received a steady volume of rainfall in recent days with an increase in grass growth rates imminent. It is important to continue using temporary fencing to balance grass supply and demand and keep good quality grass ahead of lambs.

Increasing the post-grazing height will also deliver benefits in terms of lamb performance. Teagasc research recommends increasing the post-grazing sward height for lambs in June to 5.5cm to 6cm for a rotational grazing system with 6cm remaining the recommendation in July. For a set-stocking system, the advice is to increase the post-grazing height to 6cm to 7cm in June and 7cm to 8cm in July. This of course depends on grass quality with swards grazed lower where there is a higher proportion of leafy material still present at the base of the sward.

Where topping to improve quality, it is worth being careful when deciding on the area to top as a spike in temperatures could keep growth rates at a low level. When topping, there is little point in carrying out the exercise and topping at 5cm to 6cm as this will have minor benefits in improving grass quality. Swards should be cut to 4cm to bring about a significant improvement in the quality of regrowth. Continuing to apply fertiliser after grazing will also help in maintaining grass quality.

Lamb castration

Last year’s Teagasc research results showed no major differences in meat flavour between lambs finished as rams or castrates. Management is a big factor in castration decisions. Ram lambs will achieve higher growth rates but are harder to finish with a desirable fat score.

Farm infrastructure also has to be taken into account with ram lambs best finished where grazed on their own as the season progresses while the target market is also worth taking into account with Eid al-Adha falling towards the end of August and specialist finishers in some cases preferring rams over castrates.

A good balance for some farmers is leaving strong lambs entire and castrating later-born or lighter wether lambs that will remain on farms later into the season. The burdizzo method of castration can be carried out before lambs reach three months of age. Lambs should receive a clostridial disease vaccine in advance of castration and a blowfly preventative treatment.

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