Nutrition is key during the lambing cycle, says industry body Beef + Lamb New Zealand.

Veterinarian and Wormwise programme manager Ginny Dodunski says ensuring ewes are well fed in late pregnancy is critical for lamb survival, lactation and pre-weaning growth rates.

In the last month of pregnancy, the quantity of feed offered to a 65kg multiple-bearing ewe needs to lift from 1.6kg to 2.3kg DM (dry matter) per day, she says.

For triplet-bearing ewes, this needs to rise to 3–4kg DM/day once they have lambed.

She says triplet-bearing ewes cannot physically eat this quantity of feed unless they are on high feed covers of at least 1500kg DM/ha (5–6cm average leaf length), and she encourages sheep farmers to plan their triplet paddocks now.

By feeding triplet-bearing ewes to increase their intake of high-quality pasture in the four to six weeks before lambing, both lamb survival and lamb growth rates will be enhanced.

Ginny says pasture needs to be of high quality and at least 1200kg DM/ha (or 4cm high). This height allows the ewe to maximise the quantity of grass she harvests in each mouthful.

“Rumen size does not differ between twin- and triplet-bearing ewes, so while from a nutritional point of view, the two groups do not necessarily need to be separated, if one group is to be given preferential treatment, it should be the triplet-bearing ewes.”

She says ewes should be at a Body Condition Score (BCS) of three or higher, and they should be 20kg heavier at lambing than at mating.

“This takes into account lambs, membranes and fluid.

“If triplet-bearing ewes are not 20kg heavier, then they will have lost body condition and lamb survival may be compromised.”

Supplementary feeding

“If pasture is limited, then ewes carrying triplets should be prioritised for supplementary feeding with a high-energy supplement such as peas, grain or sheep nuts,” Ginny says.

“Average- or low-quality silage or hay is not recommended because of its high bulk. New feed should be introduced gradually to avoid unwanted metabolic issues.”

Tightening feed in late pregnancy does not reduce birth difficulties or bearings. However, it does increase the risk of metabolic diseases such as sleepy sickness, she says.

“Underfeeding at this critical time can result in smaller, weaker lambs, poor mothering behaviour, and reduced colostrum and milk production.”

Ginny says stocking rates at lambing depend on ewe demand (single, twin or triplet) and pasture growth rates.

At a typical August pasture growth rate of 12kg DM/ha/day, ewes weighing an average of 65kg liveweight should be set-stocked at four ewes/ha for triplets and six ewes/ha for twins.

This enables pasture growth to meet ewe demand.

Where higher set-stocking rates are used for ewes lambing in August, feed covers also need to be higher until pasture growth catches up with ewe demand.

She says if farmers are finding these pasture covers too difficult to achieve, they could consider moving their lambing dates.

Lambing kit

A well-equipped lambing kit can also help minimise lamb losses, particularly in bad weather.

Will Halliday, Beef + Lamb New Zealand’s senior manager for technical policy, says a waterproof backpack or container containing lamb covers, iodine spray, bearing equipment, dextrose solution and syringe, gloves, veterinary lubricant, a towel and a thermos of warm water will help give lambs the best possible chance of survival.

He says a 20% dextrose mix can be used as a last resort to revive weak or hypothermic lambs during a cold snap.

“Injecting the warmed (where possible) dextrose straight into the lamb’s abdomen will give it the energy boost it needs to survive.

“It is important that this is done before warming the lamb up. If you warm the lamb first, it can hasten its death.”

He says the ideal candidates for this treatment are lambs that are 4 or 5 hours old and have not fed from their mothers.

Newborn lambs will typically respond to being warmed up alone, although a dextrose injection will not harm them.

“Dextrose is not the same as table sugar, and the latter should never be used as a replacement.”

To inject a lamb, a 5ml or 10ml vaccinating gun should be connected to the draw-off tube, or the dextrose extracted using a 60ml syringe, says Will.

“A 10mm 18G vaccinating needle is ideal for this purpose – it must not be longer than 12.5mm.”

He says the dosage is 10ml of dextrose per kilogram of body weight.

“Most lambs in need of this treatment will weigh less than 4kg, so 40ml is a suitable dose.”

After preparing the injection site with iodine, the needle is inserted just above the navel and pushed in at a slight angle towards the chest.

“There should be a slight popping sensation as the needle pierces the abdominal wall,” says Will.

The solution is then gently injected into the abdomen.

“Any swelling under the skin will indicate that the needle is not inserted far enough.”