Virtually all calves arriving at a U.S. feedlot are subjected to at least a single vaccination protocol, usually within a few days of crossing the feedlot's unloading ramp. A significant number of those are revaccinated later, most likely at reimplant time.

Revaccination protocols are widely considered to be worthwhile — cheap insurance, they say — but there's never been a definitive word on the matter. After all, a trial with a few head here and there might provide some strong inklings, but it can't flesh out a trend like a much larger study.

Now, AgriLabs appears to have an answer to the question. Working in collaboration with AgSpan, a recently completed population analysis of almost 8 million head of feeder cattle taken from the AgSpan database indicates some impressive overall economic benefits to planned revaccination at 28 or more days after initial vaccination in the feedlot. In fact, the overall benefit was shown to range from more than $21 for five-weight calves to more than $6 for eight weights (Table 1).

“One of our goals at AgriLabs is to be a purveyor of information of value to our customers. We feel this analysis does that,” says Charlie Higdon, director of the Cattle Biologicals Business Unit for AgriLabs.

The analysis involved the performance and animal health program records of 7,692,482 head of feeder cattle vaccinated on feedlot arrival (within three days), with roughly half of those calves (3,777,880) revaccinated around 28 days later.

The revaccinates analyzed in this study were all part of a planned health protocol; they were not “wreck” cattle, Higdon says. Cattle revaccinated in the first couple of weeks because of health problems did not show the same benefits.

The analysis included cattle placed on feed from 2002 to 2004 at in-weights ranging from 500 lbs. to 899 lbs. The cattle represented a total of 52,292 pens of cattle in more than 200 feedlots all over the U.S., with data collected in all four seasons of the year (see Table 2 and Table 3).

The study defined an “initial vaccination” as having occurred within the first three days after arrival in the feedyard. And while different time frames of revaccination were considered, only cattle revaccinated at around 28 days after initial vaccination were included in the comparative analysis, Higdon explains.

The data doesn't identify the specific revaccination timeframe, but more than likely revaccination was accomplished when the cattle were reimplanted, typically 90-100 days before slaughter.

“Many feedyards choose to revaccinate at reimplant time to save time and labor,” Higdon says. “Since they're already running cattle through the chute for reimplants — depending on the implant protocol — many feedyard operators feel it's just cheap insurance to revaccinate with something like a three-way at that time.”

The analysis found all weights of cattle exhibited improved performance under a revaccination protocol, Higdon reports.

“Revaccination at around 28 days delivered better average daily gain (Table 4), improved feed efficiency (Table 5) and lowered death loss (Table 6) across all weights of cattle than cattle receiving only an initial vaccination,” he says. “That improvement in average daily gain (ADG) means fewer days to reach market weight, lower yardage costs and better overall performance. And, while the highest returns were seen in lighter weight cattle, there was an economic benefit at all in-weights.”

The results of an analysis of veterinary medical costs between single vaccinates and their revaccinated counterparts weren't as as positive overall as in ADG, feed efficiency and death loss, Higdon says. But there was an indicated benefit to the lighter weight calves (500 lbs.) of $3.32/head (see Table 7).

Higdon says the economic impact of the revaccination benefits indicated by the analysis was computed using a VetLife® feedyard profit calculator. Inserted were the indicated improvements in ADG, feed efficiency, death loss and medicine costs on cattle at various in-weights. Other variables in the feedlot calculator — such as purchase price, days on feed, sale price, equity and other factors that can impact profitability — were left unchanged.

Higdon says other revaccination time frames were also investigated. For instance, Daryl Meyer, a Fremont, NE-based feedyard consulting veterinarian, says he's seeing more feedyards moving to revaccination at 10-14 days after initial vaccination.

“A lot of the respiratory breaks seem to occur around Weeks 3 or 4 on good-conditioned cattle,” Meyer says. “Some veterinarians move up second vaccinations to that 10- to 14-day period to allow the animal to build its immunity and be ready to respond by that 21- to 28-day period challenge.”

Higdon says that time frame was among those investigated as part of the population analysis, but the numbers of such cattle in the database were too few to indicate a trend. As a result, only cattle revaccinated at around 28 days following initial vaccination were included in the AgriLabs study, he says.

“Our assumption was that revaccinates at 10-14 days were probably problem cattle — either high risk or they had already broken with sickness,” Higdon says.

Kynan Sturgess, DVM, of Canyon Veterinary Consultants, Canyon, TX, is among an eight-practitioner research group in the Texas Panhandle that altogether handles a population base of 5 million head of cattle/year. He says revaccination at around 28 days is rare in his area, too.

“We revaccinate some cattle at 14-21 days — cattle we consider to be higher risk for developing BRD — about 15% of our population over the year,” he says. “I'm not aware of many cattle in our area being revaccinated at 28 days unless they have a problem.”

Sturgess says revaccination is normally accomplished at reimplant time — generally anywhere from 50-100 days after arrival.

“We do have some 230-day cattle we might reimplant at 45-50 days and again at 80 days prior to slaughter,” Sturgess says.

He says the AgriLabs/AgSpan population study is “valuable,” but he would like to see a study under controlled conditions to verify it.

Higdon, however, counters that the sheer numbers of an 8-million-head population study is more “control” than one could ever create in a small pen study.

Table 1. Overall economic benefit
In-weight of cattle, lbs. Overall economic benefit of revaccinating
500 $21.39
600 $13.78
700 $9.14
800 $6.32
Table 2. Number of cattle in each treatment group by in-weight
In-weight, lbs. Initial vac within 3 days of arrival only Initial vac plus revac at 28+ days Total cattle by in-weight
500 311,818 638,920 950,738
600 705,057 1,385,494 2,090,551
700 1,580,209 1,313,094 2,893,303
800 1,317,518 440,372 1,757,890
Total # cattle 3,914,602 3,777,880 7,692,482
Table 3. Number of pens of cattle included in the study by in-weight
In-weight, lbs. Initial vac within 3 days of arrival only Initial vac plus revac at 28+ days Total pens by in-weight
500 2,436 4,897 7,333
600 4,961 10,166 15,127
700 10,306 8,697 19,003
800 8,369 2,460 10,829
Total pens 26,072 26,220 52,292
Table 4. ADG by treatment groups
In-weight, lbs. ADG initial vac Only, lbs. ADG revac, lbs. Economic benefit from revaccinating
500 2.67 2.77 $4.98
600 2.89 2.99 $4.98
700 3.11 3.20 $4.49
800 3.32 3.35 $1.65
Table 5. Feed efficiency by treatment groups
In-weight, lbs. F/E initial vac only F/E revac Economic benefit of revaccinating
500 6.31 6.13 $5.11
600 6.39 6.20 $5.40
700 6.43 6.23 $5.68
800 6.52 6.32 $5.68
Table 6. Death loss by treatment groups
In-weight, lbs. % death loss, initial vac only % death loss, revac cattle Economic difference of revaccinating
500 3.37 2.04 $7.96
600 1.88 1.40 $2.88
700 1.02 0.88 $0.98
800 0.75 0.67 $0.54
Table 7. Vet med costs by treatment groups
In-weight, lbs. Vet med costs/head, one vac only Vet med costs/head, revac group Economic impact of revaccinating
500 $20.97 $17.66 $3.32
600 $13.60 $14.13 -$0.52
700 $9.46 $11.47 -$2.01
800 $8.68 $10.32 -$1.65