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Wool growers look inside fleece quality, selection

by Wyoming Livestock Roundup

Laramie – On Aug. 7, nearly 40 wool growers from across the state gathered in Laramie at the Laramie Research and Extension Center for the 2018 Wyoming Wool Growers Association Summer Membership Meeting. The meeting provided information on a variety of topics, from meat quality to identification and sheep health to wool characteristics. 

Whit Stewart, University of Wyoming Extension sheep specialist, emphasized selection of ewes and rams to improve the profitability of sheep operations across the state and noted wool can provide tremendous opportunity for additional income.

“Selection doesn’t have to be complex,” Stewart commented. “We’re enamored with genomic selection, and that technology will benefit our industry. But, we can’t lose focus of the visual, phenotypical information that keep our sheep in line.” 

Genomics are only of value if animals’ phenotypic traits are measured and recorded, he continued. 

“We need to measure weights and phenotypic characteristics so those genomic values make sense,” he added. 

Wool quality

The first thing that comes to mind when looking at wool quality, said Stewart, is micron, but he asked producers, “What happens if we only pay attention to micron? What can creep up on us in a ewe’s fleece?”

When micron is the only selection tool for wool, the fleece becomes compressed, and belly wool begins to creep up on the sides of the ewe. More belly wool results in loss of pounds of wool, as well as loss of wool in processing. 

“As we select for finer and finer fleeces, if we don’t pay attention to length and belly wool, it can creep up quickly,” Stewart said. 

As an example, Montana State University Targhee flock was pushing extremes on fiber diameter, which resulted in extreme variations in length – by up to an inch across the sheep. 

“Even though micron was fine, we started to see a drop in the pounds of wool because of fiber diameter reductions,” he said. 

“Select on fiber diameter and add to it length,” Stewart said.

Staple length

Stewart commented, “We’ve also become a little enamored with micron, but we can’t lose focus of staple length.” 

Staple length is another important indicator in assessing quality of wool, Stewart said. Longer staple length leads to higher yields. 

“What happens if we go too far on the length side?” asked Stewart. “The crimp pattern and fineness of wool can be affected when we select too much for staple length.”

Additionally, when length is over-selected for, fleeces become more open. 

“When we think about the environments that our sheep live in, they are windy,” he explained. “If winds are higher than 30 miles per hour, open-fleeced ewes separate the fleece, and she will lose body heat, as the heat is transferred away from her body.”

Additionally, the more follicles per square inch provides for heavier fleeces. 

Single trait selection

“As we see more Merino bucks used, we see excellent fleeces that throw a lot of length and excellent fiber diameter,” Stewart explained. “I caution all producers, however, to ensure they are not offsetting performance or lamb growth by selecting for finer sheep.”

He emphasized that selection for fiber diameter leads to reduced body size and muscle development. 

“Those animals have been developed and evolved so fiber diameter and muscle are negatively correlated,” he said. 

Quality wool

Wyoming provides the highest-value wool clip in the nation, said Stewart, who noted the state’s arid environment allows for good wool production.

“The other thing is, we see marked improvements in one generation in our wool traits,” he said. “Wool traits are highly heritable – including micron, weight, density and greased fleece weight.” 

“The quality of the wool is each rancher’s to determine,” Stewart said. “Ranchers should work to their environment and their economic situation. John Helle told me, ‘Pick where you want to go and stay there.’ Following manic trends won’t get us anywhere.”

Saige Albert is managing editor of the Wyoming Livestock Roundup and can be reached at

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