Knowing what you’re feeding is key to weight gain in calves
Increased weaning weights are a production component that many producers in the Ozarks strive to achieve.
Some strategies pay off and others, not so much. Research and record keeping are keys to tracking results and making appropriate decisions.
Dr. Shane Gadberry, ruminant nutrition specialist with the University of Arkansas Extension, explained that cattle producers may want to increase weight gain of calves beyond what forage alone will support.
“Unlike systems level efficiency, individual animal efficiency is usually based on the ratio of weight gain and intake. For practical purposes we talk about feed conversion ratio which is intake per unit of weight gain,” he said.
When looking at feed conversion, the ratio can be total conversion or partial conversion. Total conversion, Gadberry said, is based on total intake and total weight gain, whereas partial conversion is often used in supplemental feed evaluation when looking at the additional feed required for each additional pound of gain.
Both total and partial conversion can be somewhat difficult to determine with the number of operation specific grazing systems, so Gadberry highly recommended that producers dig deep and look for research that fits their individual scenario.
Feed conversion will be based upon forage quality and quantity that is available, and this will in turn determine if additional inputs to try and achieve added gain are worthwhile.
“In general, when forage quality is very good and forage intake is not restricted, the partial feed conversion ratio for supplements will be poor,” Gadberry said.
He shared an example from a recent study performed by the University of Arkansas Extension regarding creep-fed calves in the spring that were on ryegrass pasture with their dams.
The partial conversion ratio of that creep feed was nearly 15:1 (15 pounds of feed to one additional pound of weight gain). It wouldn’t be cost effective to try to add weight gain with creep feed in that situation because both forage quality and quantity was very good.
The study also looked at scenarios where forage quality and quantity were lower.
“We also fed the same type creep feed in summer during a drought year. Our creep feed conversion was closer to 4:1 in that situation because forage quality was moderate and forage availability was poor,” Gadberry said.
Fescue, one of the primary forages grown in the Ozarks, can present challenges to feed conversion and weight gain. If creep fed calves are also grazing toxic endophyte infected fescue, their conversion ration can be 6-7:1. Warm season grasses during a time of limited forage availability, combined with grain, can offer a better feed conversion and better weight gain.
Some producers might consider growth implants for improved weight gain or combining growth implants with supplemental feed.
Gadberry said research is showing promising results in a study comparing steers grazing on toxic fescue alone to steers that have the technologies and supplements.