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Hybrid advantage is your advantage — now there’s a way to score it

The bit of tissue on the root of a tail hair is all it takes for a DNA test to extract a lot of useful information for managing your crossbreeding program.

Delta Genomics at Edmonton, Alta., has developed a new three-in-one product, EnVigour HX, that uses a DNA test to match a calf to its sire, give a breakdown of the calf’s breed composition, and calculate a hybrid vigour (heterosis) score for the calf.

When the breed composition of the sire is known, the remainder of the breeds identified in the calf’s DNA can be attributed to its dam and a hybrid vigour score can be calculated for the dam without having to send its sample to the lab.

It all adds up to a straightforward way for commercial beef producers to monitor genetics in their herds without having expected progeny differences for individual animals, says Delta Genomics CEO Michelle Miller.

The research to back the database for hybrid vigour scoring comes from two major initiatives in recent years — the Canadian Cattle Genome and the international 1,000 Bull Genomes projects — along with information gathered during the first half of a three-year project by Delta Genomic and Alberta Agriculture and Forestry with the goal of collecting more genomic information on crossbred cattle that will eventually be incorporated into genomically enhanced EPDs.

“In the meantime, we know that we are good at parentage and breed analyses and that there is a lot of value in measuring and managing hybrid vigour,” Miller explains.

Delta Genomics describes hybrid vigour as the tendency of a crossbred animal to deliver qualities superior to the average of both parents.

Direct, or individual heterosis, is the simplest example. When a dam of one breed is mated to a sire of another breed the crossbred calf will have a mix of genetics that tends to give it a measurable advantage over straight-bred counterparts for traits such as weaning and yearling weights.

If the dam is a crossbred, another layer of heterosis contributes to the calf’s genetic makeup. This maternal heterosis stacked on heterosis retained through each preceding generation has been proven to boost direct heterosis in offspring and positively influence traits with low heritability that are of economic importance to cow-calf producers, but difficult to measure in young animals.

Miller calls them the fitness traits. Fertility is the big one, along with longevity, overall health and adaptability or ability to withstand the elements, and lifetime productivity. Feed efficiency can also be added to the list with work by Alberta Agriculture research scientist Dr. John Basarab showing that a 10 per cent increase in heterosis translated into a $6 per head per year savings on feed costs in 2016.

Miller explains the hybrid vigour score as a proxy for the whole group of fitness traits. It’s not, however, intended to predict a growth advantage in offspring due to direct heterosis.

EnVigour HX was released in February and 10 breeds are now represented in the hybrid vigour score calculation: Angus, Charolais, Galloway, Gelbvieh, Hereford, Limousin, Maine Anjou, Salers, Simmental, and Shorthorn.

Miller anticipates an uptick in use of EnVigour HX this fall as calves come off pasture and go through the processing routine when it’s convenient to pull the tail-hair samples.

The turnaround time for test results is 15 business days, giving producers time to contemplate their crossbreeding strategy before bull-buying season.

In addition to parentage testing to keep tabs on bull performance and the quality of their offspring, she sees a lot of potential for use of the breed composition information on replacement heifers, for instance, selecting those with the highest hybrid vigour scores or planning breeding groups to improve hybrid vigour in the next generation.

Hybrid Vigour Score

Dr. Troy Drake of Drake Veterinary Services and Cow/Calf Health and Management Services at Kathyrn, Alta., gives us a ground-level look at hybrid vigour scores.

He is the founder of Herdtrax, a web-based cow-calf health and management program, and was a key collaborator on the EnVigour HX project. Approximately 2,500 calves representative of the 200,000 active cattle on Herdtrax, were enrolled each year in the underlying genomics project at Lacombe Research Centre.

Working through one example starting with a 2015 calf, EnVigour HX determined the breed composition to be 68 per cent Simmental, 12 per cent Angus and 10 per cent Hereford with lesser percentages of Charolais, Limousin, and Gelbvieh in the mix. Its hybrid score is 51.

The breed composition of its dam, born in 2006, was back-calculated to be 23 per cent Angus, 37 per cent Simmental and 19 per cent Hereford with some Charolais, Gelbvieh and Limousin, giving it a hybrid score of 76.

This particular cow’s hybrid score will always be 76; however, the score for each of its calves will vary depending on the breed composition of the sire each year. The hybrid vigour score of the same cow’s 2016 calf is 64, being 54 per cent Angus, 23 per cent Simmental with lesser percentages of Charolais, Limousin, Hereford and Gelbvieh.

Drake sees hybrid scores (heterosis index values) ranging from a low of 20 to a high of 80. A cow with a high index could be mated to a bull of any breed without losing ground on heterosis in the offspring. A cow with a low index would best be mated to any breed of bull other than the dominant breed in its genetic mix to improve heterosis in the offspring.

“There’s no question heterosis works. It has been tried and tested for many years and I’m a firm believer in the science. It’s a big premise for our [Herdtrax] herds,” he says.

He recalls that it was fairly easy 25 years ago to visually determine breed type and manage a crossbreeding program accordingly — the red cows could go with black bulls and vice versa. Nowadays, many commercial herds are so homogenous in colour and conformation that it’s difficult to visually know how straight-bred or crossbred a cow is under the hide.

“Now we can test to fine tune a breeding program so instead of mating by colour we can sort based on each cow’s heterosis index to maximize hybrid vigour,” he explains.

“EnVigour HX gives us parentage and a hybrid score. Parentage is a really big deal because producers need to know which bulls in their own management system are siring the most profitable calves. The hybrid score can be used with the goal of maximizing heterosis. This is simple, low-hanging fruit for commercial producers.”

He and Delta Genomics are setting up an auto exchange program so that producers on the Herdtrax program will be able to create a DNA request file to send the information required for sample testing directly from Herdtrax to Delta Genomics and have the EnVigour HX results sent directly to their Herdtrax account.

Livestock Gentec at the University of Alberta is building a website, myherdandme.com, to help producers assess hybrid vigour score results relative to their own crossbreeding, production and marketing goals.

The Olds College Technology Access Centre has grants available to offset some of the cost of the EnVigour tests and employs students part time to help producers with outlining goals for their crossbreeding programs and reviewing test results to interpret what it all means in relation to those goals. There is no fee for the consultation and producers within manageable proximity to the college are welcome to enquire about the cost of having a student assist with collecting and submitting samples. The grants and consultations are available to producers anywhere in Canada. For more information, contact Kaley Segboer at 1-800-661-6537 ext. 4786.

For more information about EnVigour HX, visit the Delta Genomics website or call 780-492-2538.

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