A recently published Alberta study on the transport of cull cows during winter upturns some previous findings on causes of bruising, as well as common industry beliefs about boarding over some of the ventilation holes in stock trailers during cold-weather travel.
The study gives the first indication that issues in cull-cow transport may be related to pre-transport animal conditions, the compartment in which the cows travel, and management at unloading, says author Christy Goldhawk, who carried out the research for her doctoral thesis under the supervision of Dr. Karen Schwartzkopf-Genswein, beef welfare and behaviour research scientist at Agriculture Canada’s Lethbridge Research Centre in collaboration with Dr. Ed Pajor at the University of Calgary and Dr. Trever Crowe at the University of Saskatchewan.
The team’s objectives were to compare the effectiveness of assessment methods developed by others to identify pre- and post-transport animal welfare issues, as well as to assess temperature and humidity conditions during winter transport and their relationship to factors such as location within the trailer, space allowance and the use of boarding.
The study involved 17 liner loads of cull commercial beef cows totalling 673 cows, travelling from central gathering points across the Prairies to a single Alberta packing plant from January 24 to April 30, 2013. Travel time ranged from 12 hours, nine minutes, to 17 hours, 50 minutes, averaging 13 hours, 47 minutes.
Past studies suggested the high incidence of bruising on cull-cow carcasses is related to handling, space allocation, poor body condition scores, and cow temperament being on the nervous side. The new study found that none of those factors were statistically associated with the probability of bruising during transit.
Nearly all of the cows (91.6 per cent) were in prime body condition, with 6.6 per cent on the fat side and 1.7 per cent scored as thin.
Almost all of the cows (97 per cent) were scored as having calm temperaments when the calm and restless categories were combined. Handlers gauged each cow’s temperament the first time it entered the holding pen at the gathering station by the use of a line on the ground 15 centimetres long divided into three-centimetre sections corresponding with calm, restless, nervous, flighty and aggressive temperament. Animals that passed by the handler standing up to 2.9 centimetres from the gate were rated as calm and so on down the line out to 15 centimetres. This approach provides a quick way to score cattle temperament in a commercial setting.
Handlers were scored as well by a simple “yes” or “no” response for such actions as shouting, banging on the trailer, and driving aids coming in contact with any part of the animal during loading and unloading.
All loads complied with the transportation code of practice recommendation of 1.5 square metres per animal for group-shipped cattle of this weight.
The two factors statistically associated with bruising in this study were the compartment in which cows travelled and the wait time before unloading at the packing plant.
The odds of severe bruising on cows shipped in the doghouse compartment were 2.2 times greater than cows in the deck, 3.0 times greater than cows in the back, 3.7 times greater than cows in the belly and 3.8 times greater than cows in the nose.
The doghouse is to the right of the internal ramp on the upper deck when facing the back of the trailer. The L-shaped entry to the doghouse might be to blame for the bruising because cattle have to make two 90-degree turns to enter and exit it. This, coupled with the compact size of the doghouse, makes it difficult for cattle to maneuver without rubbing against the sides of the trailer.
The odds of severe bruising was 1.18 times greater when the wait time to unload at the packing plant dragged on from one to 1.5 hours.
Some degree of bruising was found on 84.4 per cent of the carcasses. Bruising on the round was 2.8 times greater than on the back rib area, 3.6 times greater than on the back loin, 5.6 times greater than on the left loin and 8.2 times greater than on the right loin. Ninety carcasses had bruises classified as severe in more than one of the six areas and 111 had severe bruising in at least one area.
The overall 84.4 per cent of carcasses with bruising is similar to the 79 per cent finding for cull cows in Canada’s 1999 beef quality audit, leading to the assumption in both reports that cull cows may be a high-risk group for bruising to start with because many are sourced through auction markets and have to travel long distances to packing plants.
Compromised cattle indicators
Cows were evaluated in the pens within 24 hours of loading for temperament, body condition, injuries and other health concerns. Behaviour of animals on the ramp entering/exiting the trailer and actions of the handlers were scored at loading and unloading. All cows were scored again after unloading.
Load scores for falls, prod use and the AMI compromised animal score at loading and unloading showed that of the 12 loads (483 cows) assessed for animal condition before loading, two loads were rated “not acceptable” and four loads were rated “serious” because of at least one cow on each load with an injury (torn, bleeding, puss-filled teats, lump on jaw, eye, ear).
One load that had scored “excellent” at loading dropped to “not acceptable” at unloading because one animal had a rubbed tail-head injury.
One of the loads went from “not acceptable” to “serious” because of a downer cow.
At unloading, 10 of the 12 loads had cows with injuries or poor udder conditions that weren’t observed before the trip. Increases in poor and/or torn udders were seen on one to five animals in each of five loads. The load with the most increase in the number of cows with poor udder conditions also had the greatest number of other injuries, most commonly rub-type injuries.
Only one load had no lame cows at loading and the rest had up to four. An increase in lameness was noted in six loads at unloading. Three had no change and, unexpectedly, three had fewer lame cows. The decline in lameness was likely due to differences in floor conditions, weather and handling, all of which can influence the gait of the cattle and subjective scoring of the gait.
There were three downers on separate loads that had to be euthanized on the trucks at the end of the trip. One had a leg trapped in a floor drain in the doghouse. The others were in the nose and belly compartments, but post-mortems weren’t done to determine whether there were contributing pre-existing conditions. Loading densities in the belly and doghouse compartments where the downers were found were 1.4 and 1.2 square metres per animal.
To board or not to board
Alternating boarding, grouped-alternating boarding and open patterns were evaluated to determine their effect on in-trailer temperature and humidity relative to each other and to outside conditions. Boarding was used on 15 of the 17 loads at the discretion of the drivers.
Data loggers secured in strategic locations on the ceiling of the trailers (except the nose compartment because of the low ceiling height) and on the outside of the trailer recorded inside and outside temperature and humidity every minute. The whereabouts and travel speed of the liners was tracked by GPS. Drivers provided supporting records including the number of cattle in each compartment.
Data from three time periods were used: the first 30 minutes of travel when temperature and humidity isn’t likely to have stabilized, another 30 minutes while travelling at 80 to 110 kilometres per hour along the same highway when steady conditions are most likely, and the stationary period before unloading at the plant.
Outside temperatures ranged from -33 C to 20 C, averaging -4.55 +/- 8.59.
When parked at the plant, the average temperature inside the trailers was 4.33 C (open), 4.56 C (alternating) and 6.54 C (grouped alternating) higher than the average outside temperature.
During the first 30 minutes of travel, the average temperature inside the trailers was 2.79 C (open), 2.91 C (alternating) and 3.51 C (grouped-alternating) higher than the average outside temperature.
Travelling at highway speed, the average temperature inside the trailers was 2.76 C (open), 1.57 C (alternating), and 0.61 C (grouped-alternating) higher than the average outside temperature.
The fact that inside temperatures didn’t increase much at all with boarding while travelling at highway speeds was a surprise. The data suggests boarding channels air flow into the trailer through a reduced number of ventilation holes, thereby increasing ventilation. In cold weather this increased ventilation reduced in-trailer temperature and humidity compared to trailers without boarding.
Another recent Alberta survey indicated cattle are more likely to die when outside temperatures go below 0 C midway through the trip. Modelling predicted a sharp increase in the probability of mortality once midpoint temperatures drop to -15 C.
Given that minimum temperatures during transport in this new published study were well below 0 C and closer to the -15 C mark, and that no cattle died on the way to the packing plant, the thinking is that each animal’s home environment may influence its ability to cope with cold and transportation during cold weather.
Contrary to the popular belief that boarding increases humidity inside the trailer, contributing to the onset of disease — especially in loads of young calves — this study found that humidity inside boarded trailers was on a par with outside humidity while the liner was travelling.
The average outdoor humidity ratio was 2.2 +/- 0.9 grams of water per kilogram of dry air and ranged from 0.1 to 5.9 g water/kg dry air.
During the first 30 minutes of travel, the average humidity ratio inside open trailers was 1.65 g water/kg dry air higher than average outside humidity ratio, whereas there wasn’t an inside-outside difference for trailers with boarding.
At steady highway speed, the average humidity increased by 0.93 g water/kg dry air inside the open trailers, again with no inside-outside difference for the other boarding patterns.
While parked at the plant, the grouped-alternating pattern created the greatest difference with inside humidity averaging 2.05 g water/kg dry air higher than the average outside humidity ratio. Average humidity inside the trailers with alternate boarding was 1.21 higher than outside humidity, which was similar to the open pattern at 1.10.
These new findings leave researchers with several gaps to fill including validating methods for accurately recording how wind speed and direction might affect the microclimate inside a loaded trailer, developing lameness and temperament assessments for use in commercial settings, establishing a standard system for pre-transport assessment of cull cows related to welfare outcomes following transport, and understanding the risk of increased bruising in cattle travelling in the doghouse.
For producers and haulers looking to give their cattle a better ride, Schwartzkopf-Genswein advises timely culling and vigilance regarding animal-friendly transport practices because even the best personnel and conditions can’t compensate for poor loading decisions.
Extra care should be taken with cull cows, she adds. Provide fresh, clean bedding, aim for transport times under 30 hours at temperatures lower than 30 C and higher than -15 C, and keep loading densities between 0.75 and 1.75 square metres per animal, depending on their weights.
Her previous studies indicate there is a tendency to under-load cows in the doghouse and nose compartments, thereby increasing the chance of injury. Both under-loading and overloading increased the incidence of animals dying or becoming non-ambulatory or lame.
She also found cull cows have a greater probability of becoming lame, non-ambulatory or dying during a long haul (more than 400 km) compared to other cattle. Even more issues show up on trips that exceed 30 hours at temperatures greater than 30 C and lower than -15 C.