Women look inside breeding decisionsWritten by Saige Albert
Casper – Nearly 100 women from across the state gathered in Casper on Nov. 12-13 at the Wyoming Women in Ag Annual Symposium, an event that focused on the agriculture issues women face on their farms and ranches.
With a full day of educational sessions on Nov. 13, the event kicked off on Nov. 12 with an evening reception and presentations by Wyoming Livestock Roundup Livestock Field Services Director Curt Cox, UW Extension Beef Specialist Steve Paisley and Greg Faxon of Zoetis.
The trio looked at selecting bulls, utilizing ultrasound in selecting heifers and the genetic tools available for selection.
In the past decades, Cox noted that expected progeny differences (EPDs) have become increasingly important in making decisions when selecting bulls.
“The foundation of the EPD is the history of that animal’s pedigree and what his ancestors have been known to produce,” Cox explained. “We put that on top of the performance of the individual and information collected from his progeny to get these numbers.”
He added, “Since 2010, the Angus Association uses genomic test results to give more accuracy to the EPDs.”
While EPDs vary between breeds, Cox noted that it is important to understand what each number means in making comparisons between sires. Maternal EPDs, he commented, can be particularly useful and are often overshadowed by carcass and growth data.
“The EPDs that the Angus Association qualifies as maternal are heifer production (HP), calving ease maternal (CEM), maternal milk (Milk), herds (MkH), daughters (MkD), mature height (MH) and cow energy value ($EN),” Cox said.
Similarly, the Hereford Association utilizes slightly different numbers, including maternal milk (MM), maternal calving ease (MCE), udder (UDDR) and teat (TEAT). They also utilize an index combining both milk and growth (M&G).
Lastly, Cox looked at the Red Angus Association’s dataset, which includes many similar EPDs.
“They look at milk (MILK), maintenance energy (ME) and a dollar value associated with the amount of energy needed to feed the cow,” he said. “Higher values mean more efficient females.”
The Red Angus Association also uniquely evaluates stayability (STAY), or the ability of the cow to stay in the herd for six years and produce a calf each year.
While EPDs provide one tool for making bull selection decisions, Paisley also noted that ultrasound provides an option for heifer selection that can have rapid, remarkable impacts.
“As we think about our ability to adapt and change, compared to our meat competitors, we are at a disadvantage. We have a long generation interval,” he said. “Using carcass ultrasounds, we can try to use our crystal ball to make better selection decisions earlier in the life cycle, whether that is the bull or the female.”
Ultrasound, he noted, is very valuable and can be collected for both males and females. In addition, data provides a selection tool for heifers that goes beyond phenotype.
In ultrasounding cattle, Paisley noted that a 17.2 centimeter probe is utilized to measure ribeye area, backfat thickness and intramuscular fat.
“Our machine automatically traces the ribeye and measures fat depth, all chute-side,” Paisley said. “We can generate the information quickly with ultrasound, and it is important because we can use it to measure yield grade.”
Ribeye area and backfat are measured between the 12th and 13th rib, and intramuscular fat is measured by laying the probe along the loin muscle.
“Typically, we want 1.1 square inches of ribeye per 100 pounds of body weight,” Paisley said. “When we see four percent intramuscular fat, that is low choice.”
In one ranch example, Paisley noted that ribeye area was 0.928 square inches per 100 pounds in 2010 on a particular group of heifers, which he described as “an extremely light-muscled set.”
“We selected the bottom 20 percent to cull and started mating different selections for the bulls,” he explained. “By 2013, when we ultrasounded the same replacement heifers, we had moved to an average of 1.07 square inches per hundredweight.”
“By removing the bottom and selecting bulls, we made a change,” Paisley summarized. “We can make dramatic changes quickly.”
In selecting for larger ribeyes, Paisley cautioned producers against always selecting for larger ribeyes.
“Bigger is not always better in the cowherd,” he said. “We probably don’t want an extremely heavily-muscled cow. The maintenance is higher, they require more feed, and the tendency to breed back is lower.”
As one criterion for selection, however, data collected from ultrasound can be useful and beneficial.
With EPDs and carcass data available, Faxon also emphasized that DNA technology has developed dramatically in the last five years and provides newer, more modern tools.
“We have been able to find DNA markers and identify carriers of diseases and traits like horned or polled,” he said. “As we have gone along, we have advanced what we know about these markers in animals.”
With over 50,000 markers in the genetic code, Faxon said that the genome is a wealth of information. He mentioned that DNA data provides the equivalent of collecting information from 14 of a bull’s daughters.
“We can also double the accuracy for EPDs,” he continued. “We have broken the analysis out into maternal, growth and efficiency, and carcass traits. Each has a slightly different impact.”
“Heifer selection was entirely based on phenotype for many years,” Faxon said. “We looked at what the heifer expressed and what we saw. That was it. This can provide more information.”
DNA tests can also provide the opportunity to make rapid changes in cattle.
“In one herd of two-year-old heifers, and we made an impact on them in a single generation,” Faxon said.
Looking at just one trait – marbling – as an example, the set of heifers averaged a score of 36 on a one-to-100 scale. On the scale, 100 represents the highest score.
“They tested those heifers and culled the bottom 20 percent,” he said. “That raised the average to 44.”
After selecting a bull in the top one percent for carcass traits, Faxon commented, “The offspring from those heifers hit 72. In a single generation, we were able to double the score.”
“In today’s world, we cannot affect things we cannot measure,” he continued. “We now have the technology to measure genetics and make massive changes. In a single generation, if we know the foundation of a single sire and dam, we can make the best decisions with the knowledge we have.”