NICOLA DENNIS

Keeping the ace up your sleeve: improving wool quality is now an option for everyone!

By Nicola Dennis

Keeping the ace up your sleeve: improving wool quality is now an option for everyone!

There was a time when New Zealand sheep farmers threw their sheep into the sea. This occurred before the pioneer of refrigerated shipping made meat exports viable. Back then, wool was big business and the local population was not large enough to consume all the meat produced.

And so, farmers "erected yards at the edges of cliffs, into which some thousands of these old sheep were driven, so that they might be knocked on the head and thrown over the precipice" (recounted by William Soltau Davidson in 1918, alleged sheep throwing occurred sometime before the first frozen meat shipment left Dunedin in 1881).

Let’s take a moment to respect the modern kiwi farmer and how far farming practises have come!

These days it is the wool, not the sheep, that walks the plank. At our place we are quite happy to donate our wool to passing birds. Our small farm is inhabited by Wiltshire ewes who shed their wool when it pleases them, usually in small dribs and drabs on all the fences that they breach. We round up our sheep (from every corner of the property) once at mating and then again for “lamb cheque time” and that is that. No shepherding, no tailing and no shearing. For us, it is best to get less from our sheep. We see no benefit in trying to harvest wool from our semi-feral, scrub-bashing ewes.

Most commercial sheep farmers are not breeding wool-shedding breeds and are, therefore, obliged to shear their sheep. If you are harvesting wool and receiving a pittance for it, then I see two options for your breeding programme. Option 1) start introducing wool-shedding genetics and earmark your woolshed for a more profitable enterprise such as calf rearing or wood working etc. Option 2) breed for more marketable wool. You don’t need me to tell you that fine wool is where the money is at.

As far as a I can gather, as an outsider to the wool world, there are three broad categories of woolly sheep. The standard meaty-woolly sheep (dual purpose breeds which use the NZ Maternal Worth index), the "cut above" woolly sheep breeds (finer wool breeds which use the mid-micron index) and the rock-and-sand-eating Merino type (which mostly use an Australian index).

There are some upcoming changes to the SIL genetic evaluation system for the Dual Purpose and Mid-Micron Wool indexes that are going to make breeding for more profitable wool a bit more "doable".

At the moment, DPW, the wool component of the NZMW, is focussed only on fleece weight. This was a good start (i.e. if you must have wool, then aim for lots of wool), but selecting only on fleece weight tends to push fibre diameter in an unfavourable direction (i.e. towards coarser, less profitable wool). Breeders using the NZMW will now have the option to add a dual-purpose wool quality sub-index (DPWQ). The objective of this new sub-index is to breed for finer, whiter wool, and so it contains traits for fibre diameter and yellowness. Work is being done to develop a less expensive yellowness measurement.

In contrast to the NZMW, the mid-micron wool index contains an abundance of wool quality traits (clean fleece weight, fibre diameter, colour, curvature, staple length), some of which may have little bearing on the profit of the wool. Some of these traits are hardly ever recorded. It is proposed that the mid-micron wool quality sub-index be pared back to three elements (clean fleece weight, fibre diameter and a visual score of yellowness). As I said, that is what is
being proposed. The geneticists are still seeking consultation on those changes.

The biggest news is that the economic value for fibre diameter is going to be made consistent across both SIL wool selection indexes (DPWQ and Mid-Micron). This means that sheep with fibre diameter measurements that "fall between" indexes (i.e. that have finer or coarser wool than would be expected for their breed) will receive a more accurate index value. This is good news for those hoping to transition to a finer wool class.

The new "for everyone" economic value for fibre diameter is going to be non-linear (i.e. it’s a curve not a line) to reflect that, in very coarse wool, the price received is not influenced by fibre diameter. I am running over my word limit, so I will sum this up with a picture.

 

economic value for fiber diameter

Figure 1. Economic value for adult fleece weight