Self Shedding Sheep

A long-term breeding programme at Massey University, crossing the traditional Romney sheep breed with a self-shedding Wiltshire, is producing detailed data on fertility, lamb growth, wool weights, shedding performance, carcass characteristics and eating quality, cost savings for producers as well the financial implications of transition to a self-shedding flock.

A decline in global wool prices over the past 30 years has seen a rise in interest from farmers concerned about the high cost of shearing compared to the reduced income from their wool clip. While many want to remain in the sheep industry, they also want and need an economically sustainable option. In 2020, Massey University began a breeding programme to understand more about self-shedding sheep.

The Wiltshire breed was introduced to New Zealand as a polled (hornless) line in the mid-1980s. The supplier of rams for this study has been breeding and farming Wiltshires since that time. More widespread breeding programmes of the breed didn’t pick up until the 2010s when the wool price-shearing differential really began to affect farmer returns.

Nick Sneddon explains while there are about half a dozen shedding breeds in New Zealand, at the time the study began, the Wiltshire had the most genetic diversity that could be brought to the project. The Wiltshire is a wool breed (as opposed to ‘hair’ breeds) and had also been the subject of the most research to that point. The Romney as a cross was chosen because it is so widely farmed in this country, and it is a well-known breed.

Nick says from a genetics perspective, one of the key outputs of the project is identifying the markers for the shedding phenotype. This identification of a ‘self-shedding’ gene could lead to the development of a diagnostic test for breeders and farmers and would allow farmers to transition quickly from a woolly breed to a self-shedding breed in a relatively short period of time, and to return to a woolly breed if the market were to shift back towards wool. They are also interested in quantifying the cost to do that over a 10-year period. Ways to speed up that process is one area of study in the PhD work currently underway.

Another area of interest is animal welfare around physiological responses to increased ambient temperatures (a recognition of a potential impact of climate change). Then there are implications of carcass yield as well as the impact on hides, sheepskins, or other by-products for textile as well as nutraceutical industries.

Nick says there have been discussions with organisations that produce genetic genotyping SNP chips* and, as the work has been funded through trusts and foundations, how this genetic IP would or could be made freely available. Which would allow the benefits of this research to be picked up faster and have a greater impact, sooner. Already, a number of scientific papers stemming from this research have been published.

Group Leader of Animal Science at the School of Agriculture and Environment, Dr Nicola Schreurs, says in order to quantify the outcomes of the crosses, in-lab meat quality ‘objective’ tests are carried out, as well as dissection studies to determine how much meat is on a back leg, which can be extrapolated to estimate yield across the entire carcass. Nicola says because the Wiltshire frame is quite tall and larger, it doesn’t look as ‘meaty’ as some other breeds, but her work has confirmed there is as much meat on a Wiltshire as a Romney.

The study is being run on Massey University farms, including Riverside, Tuapeka, and Keeble. Most ram lambs produced have entered the standard market and sold Prime, with the remainder being sold as store lambs. The ewe lambs have been kept as part of the breeding programme.

at the School of Agriculture and Environment, Rene Corner-Thomas, says there have been some pre- (or mis-) conceptions expressed by farmers in the past about Wiltshires around fertility and growth rates. She believes as people are becoming more comfortable with the look and performance of the breed, its value is rising.

Rene adds another avenue of research and one of the main drivers of the research programme has been bioeconomic modelling, looking at the cutoff was for the price of wool to cover the cost of shearing, and what could be saved in shearing costs as the proportion of Wiltshire genetics increased across a flock.

Another focus is how the environment impacts on animals carrying varying proportions of genetics (as well as how they impact on the environment). One of these areas is around shade and shelter and degrees of heat tolerance. Also the behaviour of the sheep in terms of flock movement and water requirements. To look at this, sheep are fitted with a variety of GPS trackers and temperature loggers, and water troughs have video cameras set up to observe water intake behaviour in different temperatures.

As well, there have been observed differences in lamb growth and flocking behaviour which is another area to be explored. Aspects such as mothering ability, lambs conceived and reared have shown little difference between the breeds.

The research has also provided multiple opportunities for post graduate study. A number of Masters’ students have carried out work within the programme and Rene and Nick co-supervise two PhD students, one who is genetics-focused, and the other looking at areas around production. The project is scheduled to continue until the end of 2028.

*SNP chips are micro-array tools that enable scanning of many genetic variations across a genome to identify genetic markers (a single nucleotide polymorphism, aka SNP, identifies a genetic region) - such as ‘that connected to shedding’ - within a genome for marker-assisted breeding and selection.