Judd RanchWhile inbreeding can reduce performance, linebreeding using carefully planned matings has been shown to elevate the influence of a genetic line or individual. Some extension beef specialists call line-breeding "the cornerstone of selective breeding."
Linebreeding is a ratchet mechanism for holding any gains already made by selection, while attempting to make further gains. It is a plan that breeds one sire line and preserves that exceptional ancestor's influence.
Linebreeding of livestock traces to the 1930s when agriculture's success with hybrid corn caught the interest of cattle breeders. In 1934, the USDA's Agricultural Research Service's Fort Keogh Livestock and Range Research Laboratory in Miles City, Mont., undertook a long-term study on genetic selection and linebreeding of cattle. Those studies today involve a successful linebreeding program in which a high degree of relationship - 39 percent - to the founding sire has been maintained for 18 generations. Without linebreeding, researchers note that the relationship to an ancestor 18 generations ago would be less than .001 of a percent.
In linebreeding, the idea is to always keep the amount that any one animal contributes to the DNA of any descendent at or below 50 percent.
Michael Gonda, PhD, South Dakota State University Department of Animal Science, says there are two advantages to linebreeding for a seedstock producer. One advantage, he says, is that a seedstock producer can identify sires that are carriers of genetic abnormalities and quickly eliminate those carriers from the herd.
"This will show up if you breed those sires back to their daughters. We can identify abnormalities that we don't yet have DNA tests for and don't know much about," Gonda explains.
The other advantage to linebreeding, Gonda says, is that seedstock producers can increase the relationship of their animals to a genetically valuable ancestor. Stacking the genes enables the linebred individual to transmit more characteristics than the other parent.
"We call this prepotency," he explains. "This can be valuable to seedstock producers who want to spread the genetics of a valuable, outstanding animal."
Jim Lents echoes this in his book The Basis of Linebreeding: "Linebreeding fixes and maintains certain traits within a population of cattle that then have the prepotency to pass on consistently to future generations those characteristics that have been fixed."
Animal Geneticist Dr. Sally Northcutt, Method Genetics, says that linebred cattle have fewer genetic defects and breed truer. She says the "why" behind cattle being truer is because they possess more homozygous or identical gene pairs.
"While we linebreed for a variety of reasons, one of the strongest reasons is that linebred cattle are more uniform and breed true," explains Dave Judd, Judd Ranch.
Stringent Approach Required
Implementing and maintaining a linebreeding program isn't easy. A seedstock producer must start with genetically sound individuals, and the person in charge of the program must know what they are doing and stay dedicated to the project.
Roger Gatz, Judd Ranch consultant, points out that Dave's solid understanding of the principles of genetics and how to apply the technology and strategies needed to have a successful linebreeding program have been critical components to Judd Ranch's successful linebreeding program.
Judd Ranch's linebreeding program started many years ago. Roger adds that seeds for a linebreeding program at Judd Ranch took root back in the days when a majority of breeders were focused on breeding really big-framed females and bulls.
Dave didn't agree with the "bigger is better" route. He wanted more moderate-framed, highly fertile cattle that had capacity and were excellent grass converters. He wanted a linebreeding program that concentrated on specific traits such as reproductive efficiency, calving ease and growth.
"We did a lot of research before embarking on a linebreeding program," Dave explains. "While we were aware of the work it would take to develop a successful program, we knew this was the direction we wanted to take since it would increase the uniformity and prepotency of our cattle - providing we started with the right sire."
So when other breeders were heading the "bigger is better" route, the Judd Ranch program opted for a different path.
Judd Ranch's linebreeding program began with a moderate-framed, thickly made bull named Rolls Roych. He combined outstanding performance with structural soundness and a huge scrotal circumference and was what many a cattleman would call a beefpacked machine.
"We deliberately began mating related animals," Dave explains.
Using Rolls Roych as its foundation, Judd Ranch's linebreeding program advanced with a Rolls Roych son named 
Partner, followed by Rolls Roych grandson named Grand Prix and then Freedom, who has Rolls Roych in his pedigree. The Judd linebreeding program also includes Free Agent, a Freedom son; and Top Secret, a Free Agent son.
"One of our goals from the start has been to increase uniformity and consistency, and linebreeding has helped us achieve that goal," Dave adds. "Linebreeding has also helped us eliminate genetic defects and attain genetic purity.
"Linebreeding benefits us, and our customers benefit from it as well. It's a win-win all around."
