Lamb finishing curtailed by drought

It has been quite some time since such a high number of farmers were wishing for rain with such eagerness. Farms in the east and southeast remain the worst affected and were among those who received negligible volumes of rain at the start of the week.

Many of these farmers started the week placing much hope on Met Éireann’s uncertainty in the weekly farming forecast regarding potential volumes of rainfall on Thursday but were left disappointed. Soil moisture deficits in areas worst affected by drought will need significantly more rainfall to have any chance of grass supplies returning to some semblance of normality.

Therefore, with grass supplies likely to remain tight and a subdued start to the store lamb trade limiting an alternative outlet, farmers are left with no option but to progress with alternative finishing plans. This has also come increasingly under the spotlight in recent weeks with factories reporting substantial numbers of lambs killing out-of-spec (lacking flesh or carcase weights falling below 17kg).

Concentrate supplementation

This week’s rainfall will help farmers in the west and northwest and may reduce pressure on grass supplies. However, it is still important not to fall into a trap of failing to take action early enough, and ending up with a high number of lambs competing with ewes for grass, or becoming stunted and ending up requiring a much longer finishing period and higher levels of concentrates to finish. Feeding concentrate will reduce grass demand. Tim Keady, Teagasc Research Centre, Athenry, says that each 1kg of concentrate replaces 0.6kg grass dry matter.

The optimum level of supplementation will depend on grass supplies and the type of lambs being supplemented. Where grass supplies are relatively good but quality is average, a daily allocation of 0.3kg to 0.5kg will enhance performance.

Where grass supplies are depleted or practically scorched/burnt, performance will be poor and nearly entirely reliant on the level of supplementation. In such cases, supplementation will need to be increased to between 0.7kg and 0.8kg to keep performance at a reasonable level (daily liveweight gain ranging from 150g to 180g). This level of supplementation may be most suitable to lambs which are a significant distance off finishing and would end up consuming high levels of concentrates if fed high amounts. It is also more suitable to ewe lambs that will be retained for breeding with the aim of keeping these lambs thriving until grass supplies recover.

The area where a better response will be achieved from feeding higher levels is with lambs that will reach slaughter condition after a short finishing period. Ram lambs have the ability to achieve higher performance than wether lambs, which grow faster than ewe lambs. Also, ram lambs have a lower risk of going over-fat. Overfeeding ewe lambs will result in fat carcases.

Again, targeted feeding in troughs over ad-lib finishing will limit costs escalating with lowland lambs capable of consuming an average of 1.3kg to 1.4kg daily where fed ad lib while individual intake can rise to as high as 1.7kg/day during the finishing phase. Table 1 details intake volumes per head for a range of feeding periods, while Table 2 shows the costs that can escalate at a given feeding period of six weeks.

Feeding in troughs will also represent a lower startup cost for many with timber troughs costing in the region of €15, while galvanised troughs cost anywhere from €30 to €45. If going down the route of ad-lib feeding, it becomes important to segregate lambs and feed according to weight. Some farmers have already implemented such an option and are targeting increased market demand ahead of the Eid al-Adha festival on 22 August.

Concentrate type

With regards to concentrate formulation, Tim Keady says the focus should be on the inclusion of high energy ingredients. The protein content of the diet will depend on volumes being fed and Tim says that, in general, a concentrate with a protein content of about 14% will suffice. Cereals should be top of the inclusion list but sight should not be lost of what feeds represent good value for money.

For example, barley is currently in short supply with feed merchants prioritising inclusion in their own formulated feeds over-selling straights. Tim says that maize is a good feed with a superior energy value (metabolisable energy of 14.8MJ/kg DM compared with 13.3MJ/kg DM for barley) and can be incorporated into diets with an inclusion rate of up to 40%. Feeding pelleted rations prevents selection of preferred ingredients in the trough and Tim explains leads to a more balanced intake.

In terms of ingredients that can be used to balance cereals, sugar beet pulp and soya hulls are good options with the latter representing better value for money. In terms of protein inclusion, while soya bean is the best protein source, Tim says rapeseed and maize distillers offer good value for money and are a good option for finishing lambs.

Feeding regime

On many farms, lambs will be accustomed to concentrates given that ewes were supplemented for a prolonged period this spring.

Tim advises to build feeding levels up slowly, starting at 0.3kg to 0.4kg and building up to 0.8kg to 1kg over a seven- to 10-day period. Where feeding such levels, the advice is to split feeds into a morning and evening feed to facilitate a fast buildup and limit potential digestive upsets.

This is another reason why feeding in troughs is preferred to feeding in ad-lib feeders. Tim highlights that access to water close to where lambs are being fed is critical and where ram lambs are being fed high volumes the diet should include 0.5% ammonium chloride to help prevent urinary calculi.

Lambs will perform equally well outdoors with indoor feeding only potentially benefiting from feeding facilities. In terms of offering roughage, lambs will not require a source of roughage where there is a supply of stemmy or scorched grass but if there is no grass available, there will be a benefit to be gained in offering lambs hay. Silage is not as viable an option as quantities consumed are likely to be small and there is a higher risk of feed spoiling quicker in current high temperatures.

Tim advises that when concentrates are being fed in moderate to high levels that kill-out percentage will increase. Evidence from Athenry shows that the kill-out rate will be increased by up to 5%, enabling drafting at lighter liveweights. To achieve a constant carcase weight, lambs can be drafted 3kg to 4kg lighter if they have been offered moderate to high amounts of concentrate.

Managing ewes

Many farmers have reduced grass demand by tightening up ewes post-weaning. This worked well but farmers are now faced with preventing excessive weight loss and getting ewes back on track for breeding. Similar to lambs, the starting point is assessing ewes and breaking up into groups to allow targeted feeding.

Ewes in a good body condition score (BCS 3.5 to 3.75 upwards) can afford to lose another small amount of body weight (5kg) and can continue to graze poor quality swards or be supplemented with average quality forage.

Ewes in poor body condition (BCS 2.5 and under) will take eight to 10 weeks grazing on good-quality grass to regain one body condition score (average of 10kg to 12kg liveweight) and should be given priority access to grass or supplemented with good quality forage.

Tight supply

Where forage supplies and grass are in tight supply, feeding 300g to 400g of a cheaper feed such as soya hulls or beet pulp will help to underpin condition. A similar feeding level may be required in the short term for early lambing ewes commencing the breeding season in the absence of sufficient grass supplies.

The target should be to maintain BCS or reduce it slightly. Grazing swards down to 2.5cm to 3cm should suffice maintenance.

Also, tight grazing should ensure high feed value herbage when regrowth commences which, in turn, will facilitate increased liveweight gain in the breeding flock and remaining lambs. While ewes may be in poorer body condition than desired at joining, Tim says it is critical that they have the opportunity to increase BCS in early and mid-pregnancy to be in good condition for lambing and lactation.