Match Cattle Numbers to Forage ResourcesThu, 01 Apr 2010 6:00:52 CDT
Commercial cow-calf operators must become more cost-efficient to maintain or improve profit margins, making matching animals to forage resources more important than ever. Land, fertilizer, feed, fuel and labor costs continue to increase relative to the value of carcass beef and weaned calves, reminds David Lalman, Oklahoma State University professor of animal science.
“One logical solution is to select and breed cattle that are productive in a given environment while requiring minimal labor and supplemental feed inputs,” he said.
Planned crossbreeding systems have been shown to increase lifetime kilogram of calf weight weaned by 25 percent compared to purebred cows. Nevertheless, breed association registration records suggest that the use of planned crossbreeding systems in the United States has declined in recent years. “Industry trends suggest that standard genetic prediction tools such as Expected Progeny Differences and selection indexes have been embraced by producers, leading to substantial change in the past 15 to 20 years,” Lalman said.
For example, the genetic trend for weaning and yearling growth, marbling and rib eye area EPDs have increased dramatically in each of the five breeds of cattle with the greatest number of registrations in the United States. Concurrently, the genetic trend for birth weight and mature cow size appears to have stabilized.
“While many of the genetic changes likely represent positive trends in commercial cow-calf enterprise profitability, some trends require closer scrutiny by academic and industry leaders,” Lalman said. “As an example, the genetic trend for increased milk yield continues at an alarming rate in several popular breeds.”
Lalman classifies the trend as “remarkable” given the increased requirements for maintenance energy, production energy, crude protein and forage dry matter intake associated with increased milk yield. “Within breed adjustment factors for maintenance energy requirements associated with increased milk yield are needed,” he said. “Recent research suggests that in some environments, forage quality limits expression of full genetic potential for milk yield. This scenario should lead to no improvement in calf weaning weight while cow maintenance costs continue to increase.”
Lalman believes continued selection for increased muscling and increased growth also should be scrutinized for their potential effect on beef cow efficiency. “In general, mature size of purebred cows has hit a plateau and may even have declined a bit over the past 10 years,” he said. “Commercial cow size typically lags behind by several years.”
Considering the extremely large-framed cattle that were around in the late 1980s, cows are large and heavy today but not extreme in frame size. “Still, there are individual producers who have not kept as close an eye on cow size as they should have been,” Lalman said. “To expect large, heavy milking cows to be in moderate body condition at calving and maintain condition through breeding, they must receive more feed than small lighter-milking cows.”
As a practical matter, reduced stocking rates will be necessary on improved pastures if lower amounts of fertilizer are applied. A larger mature cow size also affects the principle of percent of body weight needed for heifers to reach puberty. For a cow that eventually will weigh 1,000 pounds, the target weight for the heifer would be 650 pounds. For a cow that eventually will weigh 1,250 pounds, the target weight would be 812 pounds going into the heifer’s first breeding season, if the producer is to promote a high cycling and pregnancy rate.
More informtion on this subject can be found on the OSU website at Cow Calf Corner.
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