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Feeding to increase the live lamb crop

Until recently, the strongest interest in compound feed for ewes at lambing time came from stud breeders who produce high-value stock and have an interest in demonstrating a high-lambing percentage. With recent changes in the market, such as swine fever affecting global meat supplies and a general upward trend in lamb prices, it makes more sense than ever to feed ewes to minimise lamb losses.

Prolific ewes that produce more lambs are well suited to smaller farms and can help offset the cost of carrying a ram for a small flock.

Indeed, improved lambing percentage makes the biggest contribution to higher profits on sheep farms*. Beef + Lamb NZ have found that average lamb death rates range from 5 to 26 percent between farms and are higher for multiples than singles. About 60 percent of lamb deaths are caused by dystocia (obstructed labour) in singles and starvation/ exposure mostly in multiples. High birth weights (mainly singles) increase the risk of dystocia whereas low birth weights increase the risk of starvation/ exposure (mainly multiples).

Dystocia is mainly caused by the difficulty of passing large single lambs but can occur with small weak lambs so it is worthwhile looking at the size of lambs being lost. Starvation and exposure losses are greater when lambs are small and lack body reserves born to ewes who lack colostrum. Triplets are at more risk of exposure/starvation than twins but are important if the lambing percentage at tailing is to increase.

Good ewe nutrition in late pregnancy and early lactation improves lamb survival and early growth rates but must be appropriate to the needs of the ewes. It is important to feed ewes, especially multiple bearing or those in thin condition, well during the last 6 weeks of pregnancy to minimise ewe body condition loss and improve fat reserves on lambs when born. This minimises the risk of ewe metabolic disorders and improves colostrum production and subsequent milk production which peaks 24 weeks after lambing then gradually declines.

Low-energy, high-bulk feeds like hay and baleage are not good supplements to grazing for ewes in last pregnancy. Supplementary feeding with grain-based compound feed is a convenient way to fill a feed pinch and deliver essential major minerals, trace elements and vitamins. NRM Sheep Nuts are a good option in late pregnancy to reduce the risks associated with underfeeding or stress from bad weather. Typical feeding rate is only 150g/head/day but more can be fed if required.

With additional energy and by-pass protein, NRM Sheep Triplet Nuts are designed specifically for pregnant ewes bearing triplets (or more). They are typically fed at 200g/head/ day. Sheep Triplet Nuts can be fed to any ewes after lambing if pasture quality or quantity is lacking. Ewe lambs born to ewes fed well during pregnancy have been found to have better lifetime production than those from poorly fed ewes, meaning good nutrition can lead to increased flock performance in the long term.

For further information, contact your local Nutrition Specialist.

* Beef + Lamb NZ, ‘Making Every Mating Count’, 2013. Article supplied by Dr Rob Derrick, NRM Lead Nutritionist.