For the month of August lambs on good-quality grass should be achieving a weekly weight gain of 1.5kg or just over 200grams per day according to Teagasc.

In its latest advice to sheep farmers it stressed that it is important to keep tabs on how lambs are performing as any reasons for underperformance need to be remedied quickly.

Teagasc advise sheep farmers to weigh 15 to 20 of your lambs and record the weights and mark the lambs so that you can pick out the same 15 to 20 lambs in two weeks’ time. Weigh lambs with full bellies immediately after they are yarded and try to weigh them at the same time (i.e., morning, evening, etc.) each time.

If the weight gain over the period is poor, the following are areas that should be investigated:

  • poor grass quality – have a look at the grass the lambs are eating – it should be mostly young, leafy material. If it contains stemmy material, this will reduce lamb thrive and swards need mowing/topping to encourage new leafy grass to grow;
  • shortage of grass – if grass supply is tight, then lambs may need supplementary concentrates until grass supplies have increased. Spreading additional fertiliser (including P, K and lime where required) will increase grass growth rates;
  • parasitic infections – Stomach worms, liver fluke and other parasites can have a negative effect on lamb performance. Just because lambs are not scouring, does not mean that they do not have a parasite burden. Take faecal samples if in doubt;
  • mineral deficiency – poor thrive can sometimes be explained by a mineral deficiency, in particular where nutrition and parasite issues have been ruled out, these should be investigated. Cobalt is the most commonly diagnosed mineral deficiency and where this is the case, regular supplementation with oral cobalt (ideally every two weeks) is advised. If other mineral deficiencies are suspected, then supplementation should only be carried out after blood analysis has proven a need for any particular mineral or combination of minerals; and,
  • genetic ability – in all sheep flocks there are lambs that have genetically high growth rates and also those that have lower growth rates. As the year progresses and lambs are drafted, it stands to reason that the lambs that are left tend to be those that have slower growth rates due to their genetic makeup. For this reason, these lambs should never be kept as flock replacements and when selecting future flock ewes or rams, try to select genetically superior animals.