Tip of The Day - October 17, 2016

Photo by Tom Semadeni

Highway

1988 Cloning in Beef Cattle

Charlie Smith

Cloning of cattle from embryos has been achieved by nuclear transfer, and repeated cloning to produce large numbers of monozygous individuals for commercial use may soon become possible. The main advantage in breeding will come from identifying and using superior clones, selected to fit particular husbandry-marketing niches. Two types of clones will be required, terminal clones chosen for economic merit in production traits, such as growth and carcass, and maternal clones chosen for reproduction and maternal traits, such as short calving interval, ease of calving, milking and mothering ability and small mature size.

Clonal selection and use provides several steps in improvement, an initial gain by recruiting clones from elite stocks, and further responses by selecting the best clone, or clones, and by reducing and even reversing the lag between breeding and commercial clones. For continuous genetic improvement, genetic variation can be maintained by breeding the next generation from a number of selected male and female clones and testing and selecting their progeny to be the new set of clones.

For maximum improvement rates, both male and female clones will need to be tested. In the short term, benefits will come from testing a large number of clones and gains in economic merit of 15 to 30% of the mean can be achieved. Further improvements will come from rebreeding the best clones and testing and selecting the new set of clones, and annual genetic response rates of 2 to 3 % per year are possible. With large lifts in economic merit from clonal selection and their commercial use, and enhanced annual genetic response rates, cloning offers considerable advantages in the improvement of beef cattle.

Note: Hanoverhill Starbuck, a dairy bull, was cloned at the age of 19 years, and at least one living clone was produced. Starbuck also had a large number of AI progeny. At least half of those progeny had a better chance to be genetically superior to Starbuck himself, than did any of his clones. The government, however, made it illegal to sell semen from the Starbuck clones, and never did approve that technology. Luckily, SNP and marker assisted selection offered greater genetic potential later on.

Photo by Tom Semadeni

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