Dorian Garrick scopes the range of options for wool off the typical New Zealand sheep farm.
Early in my career, a typical family sheep and beef farm in New Zealand earnt roughly one-third of its income from wool, roughly one-third from sheep meat, and the rest from cattle.
The woolshed was a stimulating workplace at shearing time, with the hard-working team, the competitive environment, and the high value of the product being harvested. At that time, those few individuals that had knowledge and experience with wool classing were held in high regard.
The approaches used to improve reproductive performance and lamb growth rates by selection were based on considerable scientific efforts. They were in concert with the onfarm activities of the enlightened ram breeders and the interest of industry to support activities such as Sheep Improvement Limited (SIL) and its predecessors.
Economic circumstances have changed, and the costs associated with harvesting wool now typically exceeds its value. Securing a shearing gang can be difficult. This leaves sheep farmers with three options.
The first is to continue with the status quo, buying the same kinds of rams as in the past, and hoping that the wool market will turn around.
Other options involve changing the sheep policy, and seeking different kinds of rams from the usual Romney-based dual-purpose breeds that have been the mainstay of NZ sheep farming.
When wool prices were high, the industry did not believe anything needed to be done. When wool prices were low, the industry argued they could not afford the investment.
Those other options include changing to some other kind of sheep with finer wool that attracts a premium price per kg that increases wool income. Or changing to some other kind of sheep that sheds its fleece avoiding the costs and effort associated with dealing with wool.
If wool is finer, it is more versatile for processing and manufacturing as it can be made into finer yarn. If it is sufficiently fine it is sought after for fashionable and sporting clothing. Such wool can attract prices that well exceed the harvesting costs, and in some climatic regions of the country can result in fine wool production being a profitable farm enterprise. The improvement of wool value by reducing fibre diameter did not benefit from the same effort or scale as had been applied for improvement of reproductive performance or growth rates, and did not achieve similar success.
There were economic considerations. When wool prices were high, the industry did not believe anything needed to be done. When wool prices were low, the industry argued they could not afford the investment.
Heavy, fine wool difficult
There is also a biological phenomenon making selection for heavy, fine-wooled fleeces difficult in Romney-type sheep. This is due to the fact that the weight of clean fleece per unit skin area is determined by the product of the density of the follicles that produce the wool fibres, the mean density of the fibres produced by each follicle, and the amount of fibre extruded from each wool follicle.
In order to maintain fleece weight in a finer-wooled animal, it would be necessary to simultaneously decrease the diameter of the fibre produced, while increasing the density of the follicles on the skin surface, to counterbalance the reduced weight from finer follicles. However, selection for reduced fibre diameter in Romney-based breeds tends to be associated with a correlated substantial reduction in fleece weight. This is just a fact of nature, that most breeds other than Merino do not exhibit sufficient genetic variation in follicle density to provide for selection to reduce fibre diameter while maintaining fleece weight.
Merino and Merino-derivative breeds are different from Romney-based breeds in regard to the genetics of wool follicles.
Those Merino-type breeds do exhibit substantial genetic variation in follicle density, due to variation in the density of primary wool follicles, and in the ratio of secondary to primary follicles.
Crossing Merinos with dual-purpose breeds makes it much easier to simultaneously select for reduced fibre diameter while maintaining fleeceweight, by increasing follicle density. But measuring skin follicle attributes is much more difficult than counting lambs, characterising growth rates, or collecting greasy fleece weight. Furthermore, Merino breeds tend to have other attributes that do not predispose them to achieving high levels of performance in high rainfall areas.
Numerous attempts to produce and farm fine-wooled Merino-type sheep in the North Island have been less than successful, over more than half a century.
In an ideal world for ram buyers, there should be options of buying high-performing rams that are dual-purpose, or buying similar rams with respect to the entire portfolio of attributes except for having finer wool, or buying similar rams with respect to the entire portfolio of attributes except for producing offspring with shedding ability. This would be comparable to being able to buy the farm 4WD utility in a choice of colours, or a choice of double cab and flat deck options etc.
Sadly, and for a variety of reasons, such options do not exist in the ram marketplace for commercial sheep farmers. The only practical options include considerable choice for high-performing dual-purpose rams, a few choices for Merino-type animals that are likely not well-suited to high-rainfall areas, or a few choices for straight or crossbred Wiltshire animals of mostly uncharacterised merit for many important traits.
Significant investments have been made by dual-purpose ram breeders not just to improve reproductive performance, but also resistance to facial eczema, and improved resistance and/or resilience to internal parasites.
Fine wooled or shedding sheep may not be best
The perceived value of increased wool income from farming finer-woolled sheep could easily be offset by replacing your sheep flock with one which has a lower reproductive performance, and/or poorer lamb growth rates, and reduced resistance to facial eczema or internal parasites.
Similarly, any savings from reducing wool-related expenses by using a shedding breed such as Wiltshires are of little benefit if other income sources such as those associated with reproductive performance and/or disease are compromised.
There are other complications in making these changes. Changing breed composition at any national scale has to start by changing ram breed, to produce first-cross offspring that can then be back-crossed to that same ram breed in a manner known as grading up. The breed composition of the new ram breed will increase in successive lamb crops from ½ in the F1, to ¾ in the back-cross, then to 7/8, 15/16ths and so on.
This has several implications.
First, the farmer will not really know what to expect with the new breed in terms of whole-system performance until they have significant numbers of ¾ or 7/8 animals in their flock and they have had the opportunity to observe all traits including survival, longevity and adaptability. This takes a number of years.
Second, the first-cross animals will exhibit heterosis, that might be significant for some traits. This may mislead the farmer into expecting even more performance from animals in the next crop of ¾ bred offspring. If the superiority of the first-cross is due to heterosis, the advantage will diminish in subsequent generations.
When Holstein sires were first introduced into NZ, many dairy farmers were impressed by the amount of milk their daughters produced. It was not until the backcross that it was recognised that the increase in milk income was not sufficient to make up for the reduction in reproductive performance when high percentage Holstein animals were farmed in the same manner as most farmers had been used to.
The reduction in reproductive performance increased replacement costs, and reduced the proportion of early calving older cows in the herd, such that expected increases in whole farm profit were seldom realised.
Some modern approaches to selection can be used to produce new strains of sheep that retain the attributes farmers cherish, while introducing the new features such as finer wool or shedding.
The process is common in the plant breeding world where it is known as trait stacking or gene stacking. It involves the use of genomics along with phenotyping to carry out what is technically referred to as marker-assisted introgression, or genomic introgression. It needs to be done at scale, requiring partnership between science and industry players.
Genomic introgression for complex traits has not yet been done in sheep anywhere in the world. This is the case for several reasons. It takes a few years, and it will be expensive in terms of genotyping and phenotyping for a ram breeder to do it alone.
The technical aspects associated with the genomic technologies are not known to ram breeders, and there are no off-the-shelf solutions. The long-term returns rely on a market for these new improved animals, and most ram breeders have been reluctant to give up on wool, or to give up on the breeds they are accustomed to.
Lack of funding
Scientists cannot attract funding for such commercial endeavours without industry pull. And the timeframe for delivery is beyond that which is typically of interest to organisations such as those that control levy funds, or government funding.
The approach will not be uniformly successful for every trait, it will depend upon what we refer to as the genetic architecture of the trait. This comprises the number of genes involved in the trait, their distribution along the genome, and mode of gene action, including whether or not they interact with other genes in the genome. This is a phenomenon known as epistasis, one of two mechanisms that cause what is known as non-additive inheritance. Genomic introgression to produce fine-woolled Romney-type sheep, or shedding Romney-type is an opportunity yet to be exploited.
Sheep research is not an area that has been well funded in NZ for many years. Professors Paul Kenyon, Steve Morris and Hugh Blair initiated a small study at Massey’s Riverside farm. It is to document the comparative annual productive and financial performance when a portion of the flock was crossed and backcrossed to Wiltshire sheep.
Industry funding was not readily available for such a project, as apparently “farmers were already doing this”. Nevertheless, the study is proceeding at a small scale, and has already generated more farmer interest than many of their previous research endeavours such as those focusing on mid-lamb shearing, lifting hogget reproductive performance, or improving triplet survival and growth.
Many other farmers have come forward and indicated they are involved in similar changes to their sheep breeds, either to finer-woolled or to shedding sheep. This is despite the uncertainties of budgeting the likely productive performance of their flocks over the next 5-10 years.
Is it not time there was a collective attempt to use a modern scientific basis to produce some new strains of sheep that are fit-for-purpose for NZ. Sheep which can maintain the foundation attributes for productive, reproductive and disease traits that have taken many decades of ram breeding passion and effective selection? Who will step up and champion such progress in the NZ sheep industry?
