University of Idaho
University of Idaho
Beef producers with cow-calf herds want efficient cows that last a long time in the herd. Some heifers are more efficient than others and some do a better job in range conditions.
The University of Idaho’s Nancy M. Cummings Research, Extension and Education Center near Salmon, Idaho, has begun a study to evaluate groups of heifers in two different environments. John Hall, extension beef specialist, is in charge of the project.
“Now that we have the Rock Creek Ranch near Hailey, Idaho, we can compare heifers raised in traditional rangeland environment with heifers raised here on irrigated pasture at the NMCREEC,” he said.
“Some of our heifers spend part of their life on range as young calves, and some spend that early part of their life on irrigated pasture. After weaning we put them on two different treatments,” he said.
One group is on alfalfa and the other group is on grass during the post-weaning stocker period.
Then all the heifers are tested for feed efficiency.
“We want to find out if there is any effect of pre-weaning environment on reproduction and life-long productivity — longevity in the herd. We are also looking at whether there is any relationship between feed efficiency and reproduction,” Hall explained.
He and his students are looking at follicle counts in these two groups of heifers. After they reach puberty they are examined with ultrasound to see how many antral follicles can be seen on the ovaries. The antral follicle count is a measure of egg supply for the future.
“Studies have shown there is a relationship between animals that have a high antral follicle count and increased fertility and longevity,” Hall said. “We are also looking at reproductive tract scores, and how well these heifers become pregnant to AI at their first breeding.”
This project is in its second year. The different groups of heifers will be followed through their lives as cows; about half the heifers in this study will end up staying in the university herd.
Another study with these heifers, by Brenda Murdock, is looking at whether there are gene markers for range adaptability and longevity. A ranch with a range operation could then select heifers that work best in that environment, expressing different genes than heifers that do best on irrigated pasture and not so well on range.
At this point there are 140 heifers in the study this year, with roughly 70 heifers growing up in each environment. The same cows go to the same environment each year.
The cows in both groups are similar in breed.
“When we allocated the cows to go to either range or irrigated pasture, we split the herd in half with an equal number of cows with similar traits, based on cow body weight, cow age, breed of sire, and productivity of that cow. We tried to equalize all of those things across the two groups; each group has some similar cows,” Hall said.
The cows are all bred to similar bulls. In this study, everything about these cows is the same, except the environment, to see what the environment by itself will do in determining future productivity of these various cows. The herd is basically Hereford-Angus cross.
The steer mates from these heifers are also being evaluated, to see what the effects of these two different environments might be.
“We are looking at weaning weight, growth rate, feedlot performance and carcass composition,” Hall said.
Range-raised calves are not as big in the fall as pasture-raised calves, but tend to catch up in the feedlot. This study will look at whether they make up that weight and when they make it up, and whether the carcass is affected.