*Krissa Welshans holds a bachelor's degree in animal science from Michigan State University and a master's degree in public policy from New England College. Welshans has long been involved in agriculture and has worked with numerous agricultural groups, including the Animal Agriculture Alliance.
WEANING calves in the fall is routine for beef cattle production. However, drought conditions in the Plains states in recent years prompted some beef producers to wean calves earlier than usual.
According to recent Kansas State University studies, this may have been surprisingly beneficial.
"The conventional weaning time has always been in the fall, when calves are around 180 to 210 days old, but there was no substantial research to show that that was necessarily the best time," said John Jaeger, a beef scientist with K-State Research & Extension based in Hays, Kan.
Bringing cows home from summer pasture, fitting weaning into crop harvest time, fall school activities and other various factors contributed to that chosen time for weaning.
"We wondered if, rather than putting growth on calves at the expense of cows, it might be better to wean them earlier," Jaeger said. "If the calves fared well, it might give the cow more time to recover from calving and lactating and improve her own body condition before going into winter."
According to Jaeger, this may be an especially important time to look at such management options as producers are planning to expand herds after cutting back for several years due to drought and the resulting lack of forage.
Jaeger, along with Extension beef science colleagues K.C. Olson based in Manhattan, Kan., and Justin Waggoner based in Garden City, Kan., conducted two studies — one in 2007 and another in 2012 — to determine the effect of earlier-than-usual weaning on calves.
The studies found that calves weaned at 120-160 days at an average of 360 lb. gained as much weight and were just as healthy as calves that were weaned later. It also indicated that the health risks and death loss were no different in early-weaned calves than in those weaned at the more conventional ages of 180-210 days.
"Previous studies by other researchers have shown that early weaning reduces grazing pressure," Jaeger said.
Additionally, he said adding a calf weighing 450 lb. at 120 days of age eats about 6.8 lb. of forage per day. So, for every 30 days early that a calf is weaned, there should be one week of additional grazing for the cow.
Early weaning also decreases the cow's nutritional requirements. The studies showed that for every 30 days early that a calf is weaned, there will be three additional days of grazing for the cow.
Cows enter fall and winter in better body condition, which trims the amount of winter supplementation needed and decreases cow maintenance costs. If the increased body condition is maintained through the winter and calving and to breeding, there is potential for improved conception rates the following summer.
Over the years, there has been a tendency to think that calves are not capable of using concentrated feed at a younger age, Jaeger explained. That belief, coupled with worries about calf stress, health risks and heat — a complicating problem in July, August and September — has often kept producers from weaning earlier.
Jaeger pointed out that through this and other research, scientists know that calves can be weaned as early as 90 days, but he added that an optimum weaning age for a beef production system has not been established.
"The optimum age in response to drought conditions is usually dictated by the severity of the drought and forage availability," Jaeger explained. "I usually advise producers interested in early weaning to wean when calves average 120 days of age. Most progressive producers have a 60-day breeding season, so calves weaned at an average of 120 days of age will range from 90 to 150 days of age."
The studies indicate that younger calves need feed that is highly palatable — meaning that it tastes good to them — and relatively high in nutrient density to offset the fact that they don't eat as much as older calves do. They also found that a feed moisture content of 20-30% is optimum.
"Familiar feeds may not have the nutrient density that you'll need if you wean calves early," Olson said.
Calves will sort their diet ingredients, so the size of the particles matters.
A follow-up study is currently under way in which the researchers weaned calves from their mothers at between 120 and 160 days, with an average of 127 days, and split them into two groups. Half of the calves were left to graze on pasture, and the other half were placed in a feedlot.
At the end of 60 days in the separate environments, the weaned calves will be put back together as a group and fed a common ration until they reach market weight.
The team will evaluate how grass-fed calves fared in comparison to those fed a high-concentrate diet and will reveal the findings in 2014.
Replacement heifer tips
There are some important research-based tips that should be used to select and develop replacement heifers to improve the longevity of any cattle herd, according to Dr. Patrick Davis, a livestock specialist with University of Missouri Extension.
"These tips are good for any producer that wants to rebuild their cattle operations and improve productivity and profitability of their operation," Davis said.
According to the U.S. Meat Animal Research Center and South Dakota beef herd data, heifers calving within the first 21 days of their first calving season had increased longevity. Heifers categorized in this group also weaned more pounds of calf over their first six calving seasons when compared to their later-calving counterparts.
University of Nebraska researcher Dr. Rick Funston reported that heifers born earlier in the calving season are more likely to conceive earlier in their first breeding season. This leads to them calving earlier in the subsequent calving season.
Additionally, he reported that steer progeny born earlier in the calving season produce higher-value carcasses compared to their later-calving steer counterparts.
"This research suggests that to improve beef cattle operation profitability, it is important to develop and select replacement heifers that conceive earlier in the breeding season, leading to them calving earlier in the subsequent calving season," Davis said.
According to Davis, producers should use the following criteria when selecting and developing replacement heifers:
"Select heifers that were born early in the calving season, as well as heifers that are sound and functional," Davis suggested. "Another criterion that should be used is pelvic examinations, which allow the producer to identify heifers that do not have a sound reproductive tract or a small pelvic area that could lead to calving difficulties."
Pelvic exams are done by a veterinarian 30-60 days prior to the breeding season. If heifers are found to have an unsound reproductive tract or small pelvic area, they should be culled from the replacement pool.
"Proper development of that replacement heifer from weaning until she has her first calf is important for her to be productive and maintained in the herd," Davis explained.
For optimal performance, Davis said heifers should be developed to 65% and 85% of their mature weight prior to breeding and calving, respectively. It is also important to monitor condition scores of the heifers, making sure they are a body condition score of five or better prior to breeding.
"Research has shown that this condition score is the threshold for optimum conception rates. Prior to calving, the body condition score needs to be six," Davis said. "It is likely the first-calf heifer will lose one body condition score between calving and breeding due to the high energy needs for growth, reproductive tract repair and lactation."
According to Davis, this will put the heifer in the optimum condition score of five before breeding.
Finally, proper development of replacement heifers requires a proper health program, so Davis also recommended visiting the local veterinarian to devise a program that works best for each specific cattle operation.