Reduce calf stress to minimize shrink

Reduce calf stress to minimize shrink

WITH record-high calf prices this fall, many cattle producers are anxiously awaiting sale day and have one common goal: selling as many pounds of calf as possible.

According to Justin Waggoner, Kansas State University extension beef systems specialist, one of the factors often overlooked in conversations about marketing a calf crop is shrink.

"On many operations, the opportunity to weigh calves prior to shipment is limited, and thus, the amount of weight change between the operation and the sale is unknown," Waggoner explained. "Shrink is essentially the loss of bodyweight associated with gathering, transporting, limiting access to feed and water and marketing cattle."

The loss of bodyweight associated with these events is inevitable and affects both buyers and sellers, he said.

Shrink is made up of primarily losses in gastrointestinal fill (rumen contents, feces and urine) and tissue shrink (cellular fluid loss), according to Waggoner. "Losses associated with gastrointestinal fill can be recovered in a few hours. However, tissue losses may require several days to recover," he said.

Factors like diet, ambient temperature, length of transport, hauling conditions and handling method ultimately influence shrink.

"Today, there are many different weaning methods used by producers to reduce the stressors associated with weaning," he noted. "However, regardless of the weaning method used, maternal separation, acclimation to a new environment, feedstuffs and transportation are all stressors that newly weaned calves have to overcome as they move on to the next production phase."

Waggoner said shrink of newly weaned calves is highly variable and will typically range from 2% to 8% of initial bodyweight.

"In some situations, shrink of newly weaned calves may be even greater as high-stress calves may exhibit limited interest in both feed and water," he said.

An Oklahoma State University study evaluated shrink of calves weaned 22 days prior to a simulated sale event, calves weaned and overnighted at the sale facility and calves weaned the day of the simulated sale. Calves weaned 22 days prior to the sale shrank 2.3%, calves weaned and overnighted shrank 4.9% and those weaned and delivered on the day of the sale shrank 3.4%.

The results of the study indicated that weaning calves for a certain number of days prior to sale delivery is better than weaning on the day of the sale, and weaning on the day of delivery is preferred to weaning and standing calves overnight prior to a sale.

Although the calves backgrounded for 22 days exhibited the lowest shrink, Waggoner said research suggests that preconditioning programs in general have a limited effect on calf shrink.

"Preconditioning or backgrounding calves prior to sale may not impact shrink but could potentially result in a premium and a potentially greater sale weight," he said.

Waggoner said it is important to remember that a preconditioning or backgrounding phase must be long enough for the calves to gain back any weight lost during the weaning phase and gain enough additional weight to offset the cost of the program.

"Shrink is essentially unavoidable but can be managed by limiting the amount of stress placed on newly weaned calves prior to sale delivery," he concluded. "Reducing shrink losses is beneficial for both the seller and buyer. The seller ultimately markets more pounds of calf, resulting in greater calf revenue, and the buyer purchases calves that will regain fill losses quickly, are more likely to remain healthy and, ultimately, (will) be more successful in the next production phase."


BVDV research

Bovine viral diarrhea virus (BVDV) infections are among the most costly diseases of cattle, with losses in U.S. herds estimated at $2 billion per year, according to professor Christopher Chase of the South Dakota State University (SDSU) veterinary and biomedical sciences department.

Diagnosed as an immune-suppressive disease, the virus shuts down the immune system and makes the animal vulnerable to pneumonia and other respiratory diseases.

Chase said when a pregnant cow becomes infected, the developing calf is at risk. If the infection occurs between 40 and 120 days of gestation, the calf will be born persistently infected, according to the U.S. Department of Agriculture.

Most cattle producers vaccinate yearly, but when testing is done, anywhere from 1% to 15% of a herd can test positive.

BVDV spreads via direct contact through nasal discharge and saliva, such as when cows drink from a tank with non-chlorinated water. It can also be transmitted through semen, urine, feces and even milk.

In 2003-04, an SDSU research station in northwestern South Dakota bought 136 cattle and wound up with 60 persistently infected calves. Of these, 26 died prior to being weaned, but the rest were brought to SDSU. The surviving calves, all of whom died within a year of contracting mucosal disease, provided Chase and his graduate researchers with "a gold mine of samples."

The team found two viruses and one mutation. In some cases, the virus incorporated part of a cow gene or another virus in the part of the genome in which most mutations take place, Chase explained, which makes developing a vaccine to prevent the virus challenging.

Through a five-year SDSU/USDA Experiment Station grant, Chase, SDSU immunology expert Alan Young and assistant professor Adam Hoppe of the SDSU chemistry and biochemistry department are examining how BVDV suppresses the cow's immune response. The ultimate goal is to develop better modified live vaccines.

Hoppe's unique microscope setup has allowed the researchers to use fluorescence to see what's happening at a molecular level in live cells.

"Adam has helped devise constructs that make these cells fluorescent all the time," Chase explained. "When certain pathways get turned on, BVDV grows even better."

The researchers want to understand "how this persistence occurs and what can be done in regard to natural immunity," he added. "Ultimately, the best kind of immunization would be to increase the mucosal immune response — antibodies secreted on the surfaces of the throat, gastrointestinal tract and respiratory system."

Research performed with Colorado State University showed that the virus quickly infects Kupffer cells in the liver, which help trigger the body's immune response.

This discovery may help the scientists figure out how persistence occurs, according to Chase, which will then lead to developing ways to prevent the virus from infecting the fetus and creating a persistently infected animal that is a threat to the entire herd.


Hoop buildings

At SDSU, members of the beefSD class, an educational program for beginning beef producers, recently had the opportunity to learn how a controlled environment may provide an option to expand beef production in South Dakota.

"With the recent escalation in land prices, it is more challenging for young people to 'buy' into the business of beef production due to the larger capital investment required and the fact that most young producers have little equity," explained Adele Harty, SDSU extension cow/calf field specialist. "Hoop Beef Systems are an alternative that utilizes a controlled environment to produce beef cattle."

She explained that although hoop systems are commonly used to feed cattle to slaughter, the system the beefSD class toured at Grand Meadow Feeders in Vermillion, S.D., was being used for cow/calf pairs.

"The system that is currently being utilized at Grand Meadow Feeders has 240 cows in a 400 ft.-long hoop barn," Harty said. "The cows are divided into three groups that calve at three different times of the year. This system has taken the weather factor out of the equation; therefore, producers can be more flexible with the calving season and target alternative marketing times with the calves rather than the heavy fall run."

The cows in this system weigh 900-1,100 lb. and are maintained at a body condition score of five.

"Nutritional management has to be monitored closely; otherwise, the cows will become over-conditioned in a short period of time," Harty said.

"One of the biggest considerations with this type of system is the location relative to reliable, cost-effective feed resources," she said.

Tim Bickett, system consultant for Hoop Beef Systems, indicated that the maintenance requirements of the cows in this system decrease by approximately 30%, which results in an overall decrease in feed needs throughout the year.

"The systems are customized to the needs of the producer and the size of the herd," Harty said, adding that there are multiple factors that make these systems intriguing.

"Just a few of the characteristics that make these hoop systems work include no wind chill, hair coats are always dry, no summer sun causing heat stress and no spoiled feed," she said.

As for any concerns of disease and fly issues in this system, Harty said this has not been a problem at Grand Meadow Feeders.

While there is a significant cost to build a hoop facility, Harty said it is not nearly as much as it would cost to buy land to run the same number of cattle.

Volume:86 Issue:38

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