Manage cows and rangeland in conjunction for maximum outputWritten by Christy Hemken
Jenkins, who works with the University of Nebraska-Lincoln Panhandle Research and Extension Center in Scottsbluff, Neb., was present at the recent annual meeting of the Wyoming Ag Business Association in Sheridan.
“Animal scientists tend to be concerned about nutrient requirements of the cows, and they let range people worry about the range,” said Jenkins. “My new goal is to change that perception and integrate the thought process.”
“The reason we have rangeland is because it’s not good enough to farm – that land can only be range and we need to take care of it, because if it’s not any good for range we’ve lost it completely,” she continued.
The first step in managing cows and rangeland as a unit begins with understanding the forage resources, determining the needs of the cowherd and setting goals for both.
“If you don’t know what you have, it’s difficult to manage it right,” said Jenkins.
“Just because it’s green out there doesn’t mean you have a good quality pasture,” she said. “Know what you have in your pasture and what its uses are.”
The first step to managing forage for a cowherd is to understand your cows’ requirements and how they affect your forage resources.
“Forage intake is affected by the mature body size of your cows, and a 1,000-pound cow and a 1,500-pound cow do not eat the same amount,” said Jenkins, saying that producers need to know if they’re producing enough beef from their bigger-framed cows to make it worth feeding them.
“Tunnel vision in regard to the goals of an operation is how you end up with 1,500-pound cows,” said Jenkins. “You may get more pounds of beef at weaning from a bigger calf on a bigger cow, but you have to consider the whole picture.”
She said the net return on the bigger cow may be less than from a smaller cow with a smaller calf because of the big cow’s profit loss on the input end. “How much are you pouring into the cow to produce that end product?” she asked. “You need to understand why the cow fits your arrangement.”
Calculating carrying capacity
Relating to the carrying capacity of the range, Jenkins said a 1,100-pound cow is average for range conditions, but that’s variable from operation to operation.
One Animal Unit Month (AUM) is equal to 780 pounds of air-dried forage consumed per month, which comes to 26 pounds of air-dried forage per day. “Assuming that 1,000 pounds equals one animal unit, you can convert the AUM’s to figure out the intake of cows, bulls and weaned calves,” said Jenkins.
For example, a 1,200-pound cow is equal to 1.2 AUMs, a 300-pound calf .3 AUMs, a 2,000-pound bull 2 AUMs and so on.
When estimating forage demand, Jenkins said that while most people don’t consider the calf until after July, her research indicates a nursing calf will eat one percent of its body weight in forage at two months old. “There’s a misconception that the calf doesn’t count for anything until halfway through the growing season,” she says.
Regarding the forage selection of a cow, Jenkins said when she goes out in the spring, 80 percent of what she eats will be new growth, and 80 percent of that will be leaves, not stems. “She’s pretty selective for having a big long tongue that wraps around grass as she eats,” she said. “It doesn’t look like she’s being selective at all.”
Jenkins said calves are more like sheep when they graze, nibbling and picking, consistently choosing a digestibility similar to a cow’s but higher in protein. Her research will find out if that’s because it’s eating different species, different plant parts or newer growth.
Nonetheless, Jenkins said whatever the calf’s selecting, he’s eating and traditional AUM calculations don’t account for that. “We may not be allotting enough acreage per pair, and because of that we may be changing the composition of the range through overgrazing without realizing it,” she said.
Calculating forage availability
According to Jenkins, eastern Wyoming averages .3 AUMs per acre, but that varies and is calculated through measuring forage availability, which dictates correct stocking rates and when to pull livestock off a pasture.
To measure forage, Jenkins said to take a ring 58.9 inches in circumference and clip the ground within it in various pasture locations, being careful to include all forage types, such as those found in lowland, rolling hills and rough hills.
“Take half and leave half,” said Jenkins of what’s clipped within the ring at ground height. “Half of the forage is available to the animal, and half is left so the plant can re-grow. Of that half that’s available, cut out 25 percent for loss to insects, trampling, wildlife, etc.”
Multiplying grams-per-inch by 50 results in a weight in pounds-per-acre, said Jenkins. The weight of pounds-per-acre needs to be multiplied by .25, because summer range forage is 25 percent dry matter. Once one finds out how many pounds per acre are available for grazing the AUMs on a pasture can be calculated.
“The amount of forage you come up with has to be combined with range condition assessment to accurately assess your stocking rate,” noted Jenkins.
The main point, said Jenkins, is whether or not it’s worth it to a producer to overgraze a range. “Though you get some gain out of the cows, you’re left with nothing. Think about the importance of managing your range, because it’s hard to reverse what you end up with.”