Throughout their lives some cattle will get shipped three or four times depending on the plan for those cattle. “We talk about moving them to stocker or feedyards from the cow-calf operation,” says Brad White, DVM, MS, Kansas State University. “Sometimes we’ll also move them within the cow-calf operation. Most beef calves will go to the feedlot and then to harvest.” Because shipping — often long-distance — is such a large part of a feed-lot animal’s life, researchers are looking at the effects of transportation of the calf to the feedlot or the stocker animal to the feedlot and how that can impact later cattle health and performance.
One of the big concerns is the risk of bovine respiratory disease (BRD). “One of the questions I would ask is how much does transportation play a role in respiratory disease?” White says. “We know there are several contributing factors to the respiratory disease complex that could be affected by how we transport those cattle.” Transport includes the immediate pre-shipment/pre-transit phase, loading the cattle, getting them on the truck, potentially commingling them, and moving them to their future location.
Knowing the magnitude of transportation effects will be beneficial in designing health programs for specific groups of cattle on arrival. White notes that several papers that have shown an increase in acute phase proteins or inflammatory proteins immediately following transportation, and most of the research that has been done looks at the physiologic response of those calves. “The physiologic response is associated with inflammation and stress,” White says. “It is also usually transient in those papers, so you’ll see there’s an increase in the inflammatory proteins and it fades out in 7–14 days. When we talk about respiratory disease, those two weeks are a critical time frame for calves when they enter the feedlot.”
Role of shrink
White says the definition that he used for shrink is the amount of weight the cattle lose from the time they left to the time they arrived. “Our specific definition is pay weight minus arrival weight when they weighed them at the yard.” Tissue shrink is the weight loss beyond what they would have lost just by withholding feed or water. Fill shrink is what you have to hose off the trailer after the cattle get out. “Tissue shrink is where we start losing actual fluids from the muscle and we may have to replenish that when they get back to the yard,” White says. “Our total expected shrink may be 5%–10% depending on the distance traveled, cattle type and conditions of the journey.”
Though we don’t know how shipping affects cattle of different ages, per se, in White’s study (see sidebar) he says his group did look at weight (which is sometimes used as a proxy for age). Lighter weight calves with higher shrink showed increased BRD morbidity while the heavier calves (>500 lbs) showed little increase in morbidity even with higher shrinks. “So you could say that the shrink seemed to affect the light weight calves more than heavier calves when looking at morbidity,” White says.
The relationship between shrink and BRD morbidity was also influenced by the season of the year the cattle arrived. Cattle arriving in the spring and fall illustrated no change in expected BRD morbidity when shrink was 2.6%–5% compared to >5% shrink. However, in cattle arriving in the summer (July–September) BRD morbidity increased when shrink was >5% compared to when it was 0 to 5%.
Shrink can be lessened with some pre-transport management. “Some things we know that prevent shrink are better feeding and better pre-transit housing, so conversely we have higher shrink when some of those things go wrong and maybe that’s part of the issue,” White says. “However, it is important to note that these studies were done on retrospective data and the results do not mean that shrink was causing the higher morbidity or mortality, but rather there may be similar management factors associated with high shrink and higher health problems.”
Shrink provides a potential measure of transportation stress, and if used as a part of an overall program, it may be a useful tool for veterinarians to help predict the health outcomes in newly arrived calves. Improved accuracy in the BRD predictions facilitates the ability to customize preventative health management programs to newly arrived cattle.
White notes that a few years ago Mike Sanderson, DVM, MS, Dipl. ACVPM, Kansas State University, looked at the NAHMS data and came up with a figure of every 100 miles of distance traveled BRDC risk or morbidity is increased by 10% (2008, Sanderson et al. Can Vet J 49: 373-378).
The research team’s recent research objective was to evaluate the potential associations between distance traveled and the health and performance outcomes in his dataset. Their data set looked the distance traveled, but they were unable to study the actual time in transit which is often variable be cause of stops, rest and variability between feedlots and truckers. “When we look at overall mortality we see that the impact of distance traveled varied by season,” he says. “In the summer, there was minimal increase in mortality until the cattle had gone 750 km; in the winter and spring it didn’t change much until they traveled more than 1000 km. We don’t know if this is truly a weather effect or more of a measure of the type of cattle that arrive in feedyards at that time of year.”
The effects of distance traveled and shrink on disease risk and performance outcomes varied between feedyards and among cattle types, seasons of arrival, regions of origin, and genders. However, both variables appear to be providing important information that can be useful in predicting both performance and health outcomes, White says.
White’s study also evaluated potential associations between mileage categories and performance variables. Morbidity didn’t increase for some classes of cattle until they had traveled 750 miles. “On average daily gain we saw that it decreased the further they traveled. The females had a little bit more of a decrease as the distances traveled increased.”
“The effect of distance traveled (or shrink) does not appear to be linear; or rather, we don’t necessarily expect an increase in morbidity/mortality for each additional mile traveled,” White explains. “There appear to be thresholds that below which health problems don’t increase much.” White says these thresholds vary by yard and cattle type, and this is an area where he would encourage veterinarians and producers to track records on their operations to start to generate some data to help improve future decisions.
“We know the stress of transport can be transient, but we observed differences in BRD morbidity and overall mortality related to the distance traveled and shrink that carried through to closeout,” White explains. “This finding indicates monitoring transport conditions could be an important factor when trying to predict subsequent health problems.” Knowing the magnitude of these transportation effects will be beneficial in designing health programs for specific groups of cattle on arrival. “These transportation variables appear to be good risk factors for respiratory disease,” White says. “If we had any indicator that good enough to discriminate between low and high risk cattle, it would be a useful tool. Look at these factors as indicators for disease risk, not causative agents. Both shrink and distance traveled are probably proxies for other management practices, and finding out other differences on the cattle may help plan disease mitigation programs.”
Trailer compartments and density
Does the section of the trailer that the calf is in make a difference in risk of illness or performance? That’s a hard one to quantify, but some researchers have been looking at the different compartments of livestock trucks where cattle stand, including vibration level, wind, temperature and other factors.
Studies done by Brad White, DVM, MS, evaluated the potential impact of being housed in intone of the eight different truck compartments in a standard transport trailer. When unloaded at the feedyard, those calves were identifi ed by trailer compartment and monitored through a backgrounding phase. “We saw a difference in average daily gain up to the point of re-vaccination based on which compartment of the truck they were in, and cattle in the rear had a little bit lower average daily gain,” says White. “They were gaining about 3.5 lbs. a day to that point. There was a higher average daily gain in the front two compartments.”
Looking at just the rear, middle and nose section, the same trend holds true, White says. “If we compare the nose or front of the truck to the back of the truck we see a difference in average daily gain.” However, White notes, it’s important to point out that this difference was transient. “We saw it by day 14 but did not see any difference when we got to backgrounding closeout at day 50.”
Some observations White’s research revealed are that cattle in the forward section of the trailer were less likely to be treated than cattle in the middle. “The interior of the trailer is not homogeneous; we need more research here to determine why,” he says.
Also, calves in compartments with less than 15 head tended to have less morbidity compared to those with more than 16 head. White makes it clear he’s not advocating shipping cattle in small lots and small trailers, but when possible, keeping them in relatively small groups within the truck by shutting gates and separating compartments may decrease morbidity.
Cattle transportation studies
White and David Renter, DVM, PhD, Kansas State University, have worked with a team of researchers and collaborating veterinarians and feedlots to collect operational data from feedlot production systems. This work was funded through a USDA grant and the objective is to use these data to generate information that will improve decisions related to preventive and therapeutic management of disease in feeder calves.
“As a part of this grant, the team has worked to identify factors infl uencing the disease risk in feeder calves in order to improve our ability to more accurately predict health outcomes after arrival,” White explains. “Variables describing shrink and the distance cattle traveled to the feedlot were evaluated to determine potential associations with BRD after arrival.”