Gene therapy

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Updated results of an ongoing research project from Gardner Angus Ranch shows how breeding typical “Southern” cows with high-quality Angus sires can significantly improve the performance and carcass value of their progeny in a single generation.

The Southern Carcass Improvement Project is collaboration with Gardiner Angus Ranch, Kansas State University and Virginia Tech, to determine how much carcass improvement can be made in one generation, using high carcass value Angus AI bulls on typical Southern-origin beef cows, representing typical Bos indicus-influenced genetics most often found in Southern states.

The group purchased 22 typical southern cows from Georgia, Mississippi and Texas to serve as donors, and flushed the first set of embryos in July 2009. For the control group, the researchers used semen from 9 representative “southern” AI bulls, all from Bos indicus-influenced breeds. For the treatment group, they selected three proven Angus AI sires, chosen for high growth, muscling ability and marbling potential. They randomly selected bulls from the two sire groups for each mating.

The first set of calves was born during April and May of 2010. They spent the summer grazing at Gardner Angus Ranch in Kansas, were weaned in November and backgrounded on wheat pasture until April 2011 when they shipped to Triangle H Feedyard, Garden City, Kan. The 57 calves went to slaughter in two groups at the end of June and July. The slaughter group included 35 Angus-sired calves and 22 “southern-sired” calves. Of the donor cows in the study, six had progeny from both Angus and southern bulls, allowing direct comparisons of the sires’ contribution to calf performance and value.

For more detailed background and earlier results, read “Quick Fix” from Drovers/CattleNetwork.

Gardner Angus recently released carcass results from the progeny groups that went to slaughter this summer. All the Angus-sired and Southern-sired calves went to slaughter at the same age, rather than at weight or backfat endpoints. So some of the lighter, lower-value animals could have finished at heavier weights and perhaps better Quality Grades with longer time on feed, but they also would have incurred higher feed costs. 

The results show considerable differences. While USDA Yield Grades were similar for both groups, two-thirds of the Angus-sired calves graded Choice, while none of the Southern-sired calves graded higher than Select. On average, the Angus-sired group finished with 103 points higher marbling scores, ribeye areas that were 0.96 square inches larger, 0.12 inches more backfat and 61 pounds heavier carcass weights compared with the Southern-sired group. These differences added up to an average carcass-value advantage of $134 per head for the Angus-sired group. The Angus-sired calves had higher feed intake in the feedyard, resulting in $41.31 higher average feeding costs, so the net economic advantage averaged $92.72 per head.

A series of short shows, linked with the following examples, provide photos and individual results from a few of the matings in the study.

Example 1

The researchers collected DNA samples from each animal in the study, using the Igenity profile to rate them for marbling score and Choice percentage. One of the donor cows, from Georgia and of mixed breed, rated “4,” a low score for marbling and Choice percentage. Using embryo transfer, she was mated to a top Angus sire, GAR Predestined, with an Igenity score of “8” for the same traits, and produced five progeny. All five graded Choice, and tested at either “7” or “8” for marbling and Choice percentage in the Igenity profile.

Click here to see the photos.

Example 2

One mixed-breed Texas donor cow produced four progeny in the study – three from a Bos indicus sire and one from a top Angus sire. At slaughter, the Angus-sired calf weighed 966 pounds, graded Mid-Choice and Yield Grade 3, qualified for Certified Angus Beef and had a total value of $1,737. The southern-sired calves graded Low- to Mid-Select, with an average carcass value of $1,550, a difference of $187 per head.

Click here to see the slide show.

Example 3

In another example, a donor cow produced one Angus-sired heifer calf and three southern-sired steer calves. The Angus sired heifer graded Choice, while the southern-sired steers all graded Select, and the heifer topped two of the three steers in carcass weight and ribeye area. At slaughter, the black heifer had a value of $1,657 compared with an average of $1,577 for the southern-sired steers, a difference of $80 per head.

Click here to see the photos.

The second set of calves in the multi-year trial is on the ground now. Once they go to slaughter next summer, the researchers will have data on more than 100 calves from the same group of donor cows, with direct comparisons of Angus-sired versus southern-sired calves from the same dams in many cases.

For more information on the trial, visit the Gardiner Angus Ranch website.


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M. Mazzocco    
Champaign, IL  |  October, 04, 2011 at 09:32 AM

Brangus.

Daniel Marvel    
Florida  |  October, 04, 2011 at 10:44 AM

Were the Bos Indicus and influence bulls selected based on carcass quality EPD’s or DNA results? Looking at the pictures of the dams most breeders even here in Florida would not have breed them back to heavy influence Bos Indicus bulls.


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