NSIP a quantitative genetic tool for sheep, goat producers
February 14, 2014
The National Sheep Improvement Program (NSIP) is a quantitative genetic selection tool designed to help sheep and goat producers make good breeding decisions, according to North Dakota State University Extension Service sheep specialist Reid Redden.
"Sheep and goats are diverse livestock species, and much of what makes them more productive cannot be identified visually, which complicates genetic selection decision making," he says.
Many traits of economic importance to the sheep and goat producer are quantitative, meaning they are influenced by many, often hundreds or thousands, of genes in the animal's DNA.
"Selection decisions based on visual cues and past records can be difficult because many of these quantitative traits – for example, carcass data, fertility, etc. – have to be measured after death or later in life for accurate selection to occur," cautions Lauren Hulsman Hanna, an assistant professor in NDSU's Animal Sciences Department who specializes in the genetic improvement of livestock. "The genetic merit of an animal, or the ability to pass on its characteristics to its offspring, can be predicted for many of these quantitative traits, such as litter size, weaning weight and carcass characteristics, using accurate and reliable records and pedigrees from each producers on his or her animals."
The U.S. beef and dairy cattle industries have used this prediction technology effectively for many decades in the form of expected progeny differences (EPDs), but the sheep and goat industries have not embraced it. "Breeders seek animals that grow fast so that lambs or kids reach a market weight faster or at heavier weights," Redden says. "However, larger, faster-growing sheep are typically less prolific. Similarly, animals that grow the fastest often do not produce a more desirable carcass or fleece. This emphasizes why selection of breeding animals requires a multifaceted approach, which can be improved by using quantitative genetics. Without this technology, many producers are left to select for one or two traits, which are primarily visual assessments."
The NSIP can help producers make use of this technology, Redden says. It is a nonprofit organization that performs genetic prediction analysis for the U.S. sheep industry. It has been in existence since 1986.
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The program recently added a goat division and is seeking goat producers to enroll in it.
This is how the program works: Sheep producers enrolled in the program submit data records from their flocks on as many animals as possible. This data is used to calculate estimated breeding values (EBVs) for individual animals, taking into account contemporary groups such as flock mates and breed, and other factors known to influence performance. The resulting EBV is that animal's breeding value, or value as a parent, in comparison with the other animals in the evaluation.
Another useful measure is the EPD, which is one-half of the EBV, Hulsman Hanna says.
Roughly 130 producers and 10,000 sheep are enrolled in the program. This is a fraction of the 4 million breeding sheep in the U.S.
"We have made a few changes this year to make it easier for purebred operators to get involved in the program," says Redden, who serves as the NSIP chairman.
"Enrollment fees have been waived during the first year to any new members. And enrollment fees are waived for three years for youth members. We've also developed a mentorship network so that all new members have immediate access to a fellow sheep breeder who can assist new members to get started and answer questions along the way."
Purebred seedstock operations are the only ones that need to enroll in the program.
"Used properly, EBVs will improve productivity on their farm and enhance how they make breeding decisions," Redden says. "However, the most value from the program will be derived when they market breeding animals to the commercial industry."
Commercial sheep farmers benefit the most from this program, he says. They are able to use EBVs to improve their ability to select breeding sheep that will improve flock productivity.
For example, the Polypay breed is known for prolificacy and maternal traits. In the last 10 years, NSIP Polypay breeders have increased the breed average for pounds of lamb weaned per ewe by 13 pounds.
The Suffolk breed, known for rate of growth and carcass merit, is another example. In the last 10 years, NSIP Suffolk breeders have increased the market weight of lambs at 120 days of age by 6 pounds per lamb while increasing loin eye muscle and reducing fat deposition.
All active NSIP breed groups have made similar progress in traits for which their breed is most known.
Redden cautions that EBVs should not be seen as a replacement for traditional practices; rather, they should be a tool to assist sheep breeders become better at what they already do. F