Sheep Industry News August 2023

to make sure the animals are on the right side of the popula tion mean. In fact, one of the great strengths of BVs is that they allow you to make progress on multiple traits that are antago nistic. The terminal traits tend to be easier to measure and easier to improve due to higher heritability rates. This improvement in evitably comes at the expense of feed cost, health and maternal function. Once this trend is discovered – often well down the road – it then takes a long time to repair. This is where indexes come in handy. Indexes allow you to put pressure on multiple traits at the same time. The key to successful indexes is the inclusion of all of the economically relevant traits. If you leave an economically relevant trait out of an index, then it is almost certain to go in the wrong direction. On the other hand, if you include them all, then you will have much more likelihood of success. Another major advantage of indexes is that they allow you to more optimally balance selection among multiple traits. Profit ability in livestock supply chains depends on a dozen or more genetic traits. The human mind is incapable of balancing selec tion of more than handful of traits at once. Instead, we often use thresholds. Thresholds typically reduce the rate of improvement on profit. Thus indexes – if properly designed – can give you the most rapid rate of improvement on overall system profitability. SGUSA: New and less expensive genetic technology is being developed at a rapid pace within the livestock sector. As you look to the future, how do you see this new technology be ing used in the cattle industry? United States. In fact, the genetic lines in the Rafter 7 flock at the University of Nevada-Reno were originally developed us ing semen from Australia, and the purebred Merino line has continued to incorporate Australian Merino genetics periodi cally since the line was established. Ongoing research by Dr. Andrew Hess is focused on as sessing the value of incorporating Australian sheep genetics and the potential for incorporating data from other countries to improve the ability to select the top-performing animals. More generally, however, the impact of incorporating genet ics from top sheep-producing countries and the ability to use data collected in other countries for the betterment of the American sheep industry is something that warrants further investigation. International Genetics Story Continued from Page 31 Leachman: In pigs and chickens, the genetic company supplies the female. In beef cattle, commercial females are selected based

on visual appraisal. Today, we are seeing genomic predictions revolutionize the selection of replacement females. Commercial herds cannot afford to collect data. However, the difference between their top 30 percent re placements and their average replacements is large. Genomics can now accurately predict these differences. Further, you can eliminate outliers that cause management problems. In cattle, those outliers would include: poor disposition, sub-par calving ease, bad udder quality and even reduced longevity. Combin ing genomics with indexes to select replacements can really supercharge the rate of genetic improvement in a commercial cow herd. Genomics also greatly increased the rate of genetic progress on traits that cannot be directly measured on young seedstock males. On the maternal side, this is almost every trait. SNP panel genomic predictions dramatically increase the accuracy of these maternal predictions. DNA enhanced selection changed the way dairy bulls were chosen and is now doing the same to beef bulls. The use of sexed semen and in vitro fertilization is currently emerging as a game changing combination. Elite females can now produce hundreds of progeny. Further, we can now pro duce specialized lines of males for maternal and terminal traits. We don’t have to make very many sisters to our terminal line males. Additionally, we can make sexed female embryos that might become cost effective for use in commercial herds. The challenge to genomic technology remains the cost of the DNA testing, but this cost is dropping. As it does so, we will see DNA being used to value replacement females and feeder cattle. Then feedlots will implement precision animal management based on genetic predictions. It’s a great time to be in the beef cattle breeding business.

Genetic lines at the Rafter 7 flock in Nevada were originally devel oped using Australian Merinos. Researchers are studying how in corporating international sheep genetics – and the data that comes with it – can benefit the American sheep industry.

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