Pahiatua farmer and former Meat and Wool NZ consultant Richard Gavigan paid $4.60 to shear his ewes and paid $3.90/ewe for the wool. But are there other gains.

Farming just south of Pahiatua, we favour later lambing to match pasture growth with the increased feed demand of our lambing ewes. The rams went out on April 26, giving us an estimated mean mating date of around May 6. We hoped that shearing during early to mid-July (we ended up shearing over three days on July 4, 10 and 17 because of wet weather) might give us some lamb production benefits, thereby offsetting the cost of removing the wool.

We drench and vaccinate our livestock to produce an economic benefit, so viewing shearing as another necessary animal health cost might make me feel better about the predicament low wool prices and high shearing costs have placed us in.

Does winter shearing make a difference?

Massey University’s Professor Paul Kenyon has spent several years researching the practice and concluded that, in some cases, it can improve lamb birth weight, lamb survival and even lamb weaning weight.

“The optimal winter shearing window to get a positive lamb birth weight and lamb survival response is quite wide, between day 50 and day 100 of pregnancy,” he said.

“The birth weight response can be 300-400g in twins and this can equate to improved survival in multiple lambs of 2-3%. Some studies have shown weaning weight increases of 1kg. On today’s lamb prices, this would more than cover the recent increase in the cost of shearing.”

However, Kenyon is quick to point out that getting an economic benefit from winter shearing is by no means guaranteed. It needs to be carefully managed to help make up for poor wool returns.

Good body condition score and energy management are critical.

Ewes must be a minimum of Body Condition Score (BCS) 2.5 at shearing. Any lighter and a birth weight response won’t occur. Ewes must also be offered more feed for 10 days after shearing. This means not grazing below 1100kg DM/ha so additional nutrients can make up for heat loss.

Kenyon explained the complex physiological mechanism for the birth weight response in simple terms.

“When a ewe gets cold after shearing, her metabolism increases to make up for increased heat loss,” he said.

“As a result, she breaks down bodyfat which puts more energy into her bloodstream. More energy in the bloodstream increases placental growth which can result in improved foetal weight in late pregnancy. The extra energy in the bloodstream also crosses into the placenta and this can enhance foetal development immediately after shearing.”

However, Kenyon said if extra feed isn’t on offer after shearing, the bodyfat mobilised will go straight into heat production and not be available for placental and foetal development responses.

“Planning for winter shearing is essential,” Kenyon said. “You need to keep a close eye on the weather, make sure you use genuine winter shearing combs, and have sheltered paddocks and saved feed ready for shorn ewes.

“The important thing is the balance between the energy available from feed and fat mobilisation versus the energy needed to regulate body temperature. If you don’t have sufficient feed or if the weather after shearing is particularly cold, you won’t get the benefits.”

Another factor to consider is although a positive weaning weight effect would improve returns, a birthweight response in single lambs could increase the rate of lamb death from dystocia (difficult birth). The ideal strategy could be to take the wool off ewes scanned with multiple lambs.

Kenyon believes that the old adage that shorn ewes that have lambed seek shelter more readily, protecting their lambs from cold weather, is a myth. If ewes have been shorn with a winter comb in mid-pregnancy they will probably have more than enough wool growth by lambing to keep them out in the cold. There may be some shelter-seeking effect if ewes are shorn in late pregnancy, but by then the optimal shearing window for a lamb birth weight response may have passed.

Shorn ewes are less likely to get cast, reducing ewe deaths around lambing, but this effect has never been quantified.

We had less feed and the ewes were a little lighter this winter because of a dry summer and autumn. We also had a long spell of cold, wet weather after shearing. Although we did our best to get everything right, I’m picking the positive mid-pregnancy shearing effect will be less significant this season. However, given the potential benefits, we’ll continue to use this important animal health and management practice.