The sedentary lifestyle is not a good thing for humans. Being a couch potato can contribute to a wide range of ills. Research is showing that there could be trouble if beef heifers have a sedentary lifestyle, too.
Work at Oregon State University is showing that beef heifers raised in close quarters are under more stress than heifers raised on pasture, and they don't get the pasture-related physical activity, either. The findings were published in the journal Animal, and may offer guidance for cattle ranchers aiming to boost herd efficiency and assure the public they're interested in the welfare of their cows, according to Reinaldo Cooke, who did the work at OSU but has now joined the team at Texas A&M University.
Cooke noted that his work found beef heifers in pens were not comfortable. Often in spring-calving, cow-calf herds, heifers are weaned in the fall. They spend the winter together in pens or pastures for protection from the elements. They're also exposed to their first breeding the following spring.
During a six-month experiment, Cooke and his OSU colleagues found that heifers clustered together in industry-standard drylot pens experienced delayed puberty, despite adequate age and body weight development.
That delay in sexual maturity has a cost for beef operations, Cooke said.
The OSU team monitored growth, physical activity and stress-related physiological responses of heifers from September 2015 to March 2016 at the university's Eastern Agriculture Research Center in Burns.
As part of the study, 60 Angus and Hereford heifers were put into three 450-square-foot drylot pens and three 60-acre pastures, with 10 heifers in each pen and 10 in each pasture. Cooke said the number of heifers kept in a pen influences whether the animals thrive and go on to produce healthy calves.
On the first day of the experiment, they measured each cow’s temperament with, among other things, how the animal handled being squeezed through a chute. They fitted each heifer with a pedometer placed inside a patch behind the right shoulder. They also collected hair samples from the animal’s tail switch to analyze cortisol concentrations. The concentration of cortisol, a stress hormone, in hair from the tail switch is a biomarker of stress in cattle.
At the end of the six-month period, the cows kept in pastures took, on average, nearly 20,000 steps a week, compared to about 3,100 for the penned heifers. The pasture heifers had lower cortisol concentrations and were better-behaved than their pen-raised counterparts. These outcomes were independent of heifer nutritional status and growth rate, because all the cows were on the same diet.
Cooke observed that heifers on pasture had to deal with snow and had little grass for grazing, but they learned to survive. "We found that our heifers on pasture, as we expected, exercised more, which is important for reproductive maturation," he concluded.
Source: Oregon State University