Wolf predation of cattle reduces calf weight

Wolf predation of cattle reduces calf weight

A RECENT study by University of Montana faculty and graduate students found that wolf predation of cattle contributes to lower weight gain in calves on western Montana ranches.

This leads to an economic loss at sale; the loss is several times greater than the direct reimbursement ranchers would receive for a cow killed by wolves, the researchers said.

The study found that wolves living on the landscape with cattle have no effect on herd weight, but once a ranch has a confirmed wolf kill, the average calf weight decreases relative to if that ranch had not experienced wolf depredation.

"Ranchers have been saying for years that wolves cause weight loss in cattle, but nobody ever had done any research on the topic," said Derek Kellenberg, a co-author on the study and associate professor and chair of the department of economics at the university.

Kellenberg worked with associate professor Mark Hebblewhite from the University of Montana wildlife biology program and graduate students Joseph Ramler and Carolyn Sime. The Montana Department of Fish, Wildlife & Parks also cooperated on the study, which analyzed data from ranches in western Montana, including 15 years of records on ranch husbandry, satellite-generated climatological data, spatial data on wolf pack locations and confirmed depredations on 18 ranches.

The study quantified the economic impact of weight loss after a confirmed wolf kill for an average ranch consisting of 264 head of calves, an announcement said. The researchers reported that a decrease of 22 lb. in the average weight of calves across the herd implies a $6,679 loss at sale for an affected ranch.

"When you compare that to the direct reimbursement of the cow that was killed — about $900 on average — these indirect costs are about seven-and-a-half times the direct cost of depredation," Kellenberg said.

The report notes that while the economic impact of lower herd weights caused by wolf depredation is not insignificant to ranchers, other ranch-specific husbandry practices and climatological and environmental variables such as annual precipitation, average temperature and snowfall explain a much larger proportion of variance in calf weight over the years than wolf effects do. In fact, these other factors explain the vast majority of the accounted-for variation in annual calf weights, the researchers said.

The study started as a senior thesis by then-undergraduate student Ramler, who collected data from public cattle auction records. When he decided to pursue a master's degree in economics, the group started collecting and analyzing data from a survey of individual ranchers in western Montana.

Kellenberg said he hopes the study will help inform policy-makers and ranchers as they work on issues related to wolf management.

"This study helps quantify some of the indirect costs that have not previously been accounted for," he said.

A report on the study was published Jan. 10 in the American Journal of Agricultural Economics.


Efficient cattle

Direct linkages can be found between farm efficiency and carbon emissions and sequestration, according to "Factors Affecting Cow/Calf Herd Performance & Greenhouse Gas Emissions," a Texas A&M AgriLife Research paper recently published in the Journal of Agricultural & Resource Economics.

Conducting the study were economist Dr. Seong Park, postdoctoral research associate Dr. Tong Wang and rangeland ecologist Dr. Richard Teague, all with Texas AgriLife Research in Vernon, Texas; Stan Bevers, economist with the Texas A&M AgriLife Extension Service, and Jaesung Cho, research fellow at the Korea Rural Economic Institute.

The paper provides the first study on the relationship between cow/calf farm efficiency and environmental consequences, as indicated by net greenhouse gas emissions, Park said. Results suggest that for the cow/calf industry, pursuing farm efficiency aligns with environmental protection goals.

"We found that carbon emissions per unit of output decrease as farm efficiency increases," Wang said. "Higher carbon sequestration occurs on farms that are more technically efficient as a result of more acres allocated to each breeding cow."

The greatest net carbon sequestration was found for the two most technically efficient groups — those that best managed the age of weaning, cost of pasture improvement and purchased feed, etc. This indicates that pursuing technical efficiency will not compromise environmental quality, she said.

Park said the Rolling Plains' beef cattle industry is inherently risky due to frequent drought conditions, volatile cattle prices and rising input costs.

In the face of these challenges, an analytical tool — the Beef Cow/Calf Standardized Performance Analysis — has been developed that helps farmers and ranchers identify their strengths and weaknesses in production and financial performance, Bevers said.

Based on the standardized performance analysis data, the study found that the factors promoting higher herd productivity included machinery investment, pasture quality improvement and protein supplements. In contrast, herd productivity is compromised by a longer breeding season, percentage of hired labor and deviation from the average annual rainfall.

"Interestingly, the more technically efficient farms tend to emit fewer greenhouse gas units per unit of output," Park said. "For example, net greenhouse gas emissions are 6.12 and -8.7 lb. of carbon equivalent, respectively, for farms with technical efficiency below 0.8 and above 0.96."

The focus of this paper was on output, or pounds weaned per breeding female, rather than profitability, he said.

"Future research could investigate whether the incentive to pursue financial profitability conflicts with environmental protection objectives," Park said. "Future efforts could also extend the method to model the link between pursuing efficiency and environmental protection in other industries, such as cropping, or in different regions."


Calf scours

Calf scours are an unwanted guest during spring calving season. Good management alone is sometimes not enough to protect the calf from scours, so cattle producers turn to practices like calf vaccination to head off diarrhea in their spring calf crop.

"There are, however, pitfalls to early vaccination that can put your calves at risk," said Bobbi Brockmann, director of sales and marketing with ImmuCell Corp.

One problem with vaccinating calves at birth is the high concentration of maternal antibodies found in colostrum. These maternal antibodies can interfere with the calf's immune response to a vaccine.

This is because they cannot distinguish between the antigens of a natural challenge and those in a vaccine, Brockmann said. When this happens, the maternal antibodies neutralize the vaccine, rendering it useless so the calf does not receive the scours protection intended by the vaccine.

"This also is the reason why some scours vaccines currently on the market require a delay in colostrum intake," Brockmann said. "However, any time there is a delay in colostrum intake, the calf is put at greater risk for failure of passive immunity."

Another problem is that newborn vaccination does not guarantee immediate immunity. The calf must respond to the vaccine in order to develop antibodies. This process takes time, during which the calf is vulnerable to disease.

Mounting an immune response to a vaccine is also a drain on the newborn calf's limited energy reserves. Instead of being diverted toward an immune response, this energy could be better used for body temperature regulation, growth and to fight off disease.

To overcome the challenges of newborn calf vaccination, cattle producers can utilize the immediate immunity available in U.S. Department of Agriculture-approved antibody products.

Concentrated antibody products can be fed to calves at the same time as colostrum, so there is no interference with maternal antibodies and no waiting for a response from the calf's immune system. It also means less stress because the calf does not have to divert its energy reserves away from maintenance and growth to mount an immune response.

Volume:86 Issue:07

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