Improvements in commercial cow/calf forage efficiency found to be smallWritten by Natasha Wheeler
“Cattle have been put under extreme selection pressure for one trait or another. The question is, over time, are we getting closer to cattle that better match our forage resources?” asked Oklahoma State University Extension Beef Cattle Specialist David Lalman.
To investigate, he considered a list of factors that would indicate efficient cows, including early sexual maturity, a high rate of reproduction, low rates of dystocia, longevity, minimum maintenance requirements and the ability to convert forage resources to pounds of beef.
“It’s a good exercise to ask whether we’ve improved in any or each one of those characteristics,” he noted.
Lalman and his team gathered data from the Kansas Farm Management Association, the Cowherd Appraisal Performance Software (CHAPS) Summary in North Dakota and the Standardized Performance Analysis (SPA) Summary involving New Mexico, Oklahoma and Texas. The data was specific to commercial cow/calf operations and did not include seedstock or purebred operations.
“The idea was to find data that represented moderate- to low-input operations,” he explained.
To begin, the research team reviewed simple indices for weaning weights across the operations. Data from the southwest region suggested that weaning weights have not changed significantly over the last 20 years.
“If we look at the Kansas data, we might argue that there was a sustained increase in weaning weight of about 15 or 20 pounds, but since 2002, that has actually been flat or even trended downward. North Dakota data looks like there was some variability early on, with perhaps some slight improvement in weaning weights over a long period of time,” Lalman commented.
Taken together, the data sets don’t show significant increases in weaning weights over the last 20 to 25 years.
“Considering the selection pressure of the industry, that’s somewhat of a surprise,” Lalman stated.
The research team also looked at milk production in beef cattle, noting there is a high demand for energy and protein for milk production in cows.
Comparing several different breeds over the last 23 years, the team noticed that most breeds have increased milk production through aggressive selection pressure.
“Milk production comes at a cost, and the year-long maintenance requirement is increased as well,” Lalman said, explaining that high milking cows require higher maintenance costs, even when these cow are dry.
“It’s related to the increased maintenance requirements related to greater visceral organ mass relative to empty body weight. Visceral organ mass is the rumen, small and large intestine, liver, heart and kidney. Of course, those are all very metabolically active tissues, and they are very expensive tissues to maintain,” he said.
According to published studies the Lalman reviewed, cows with moderate to high milk production that are then selected for higher milk production create cows with good yields but also greatly increased conversion factors, meaning that it takes more pounds of feed per pound of milk to produce those high yields.
“Beef producers need to ask themselves whether there is a limit of milk production their forage can support,” stated Lalman.
To illustrate his point, he explained that a dairy cow may have a high milk yield in her environment at the dairy with high-energy feed, but if that same cow were to be sent out onto the range in Oklahoma, her milk production we be reduced dramatically.
“There’s a limit to the amount of milk yield that the native rangeland in Oklahoma can support. Everyone’s forage has a limit. I’m guessing that perhaps we have met and exceeded that limit in many cases already,” he remarked.
He continued, “I think there’s increasing risk or frequency of cases where forage resources limit the expression of genetic potential for milk and/or production costs have increased because the environment has been artificially modified to fit the cow.”
According to his research, Lalman was surprised to find there was not strong evidence showing that commercial cow efficiency has improved when considering efficiency in a “sell at weaning” context.
“Moderation in genetic potential for milk yield should reduce enterprise risk and improve fertility due to a better match between forage nutritive value and beef cow requirements,” he concluded.