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Projects further understanding of pain in lambs and cattle stress in abbatoirs

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01 July 2016, at 1:00am

Richard Gard returns to the RVC’s interesting programme of student studies.

LAST MONTH WE REVIEWED THE PROJECTS to identify attitudes to pain with calf disbudding (Samantha Hamilton), free shooting of horses in an abattoir (Elizabeth Bedford) and a relationship between cell count and Johne’s Disease (Ben Barker).

There is considerable interest surrounding the whole topic of pain and stress and students are continuing to probe for practices and therapies that can reduce both effectively. Within the limitations of time and resources available to students, the approaches to uncovering areas of improvement are highly creditable and their initial findings are being taken forward in many instances.

Of the 32 references cited by Thomas Elwes, a quarter are papers by Temple Grandin. The welfare of cattle in abattoirs prior to slaughter is a hot topic and some of the details were highlighted by Professor Grandin at the recent Total Dairy Seminar.

Stunning study

It is encouraging that a student is able to contribute, “to identify potential causes of stress during handling and restraint of cattle being slaughtered without stunning”. Two abattoirs in the UK were recruited and the behaviour of 140 beef cattle and the human interactions recorded. The project introduction notes that slaughter without stunning can be legally practiced in the UK, provided it is performed by a licensed slaughter-man under Jewish or Islamic methods to produce food for Jewish or Muslim people.

It is estimated that around 6% of cattle in the UK are slaughtered without stunning. Fear and anxiety are recognised to heighten the experience of pain. Calm animals lose consciousness more rapidly and are less likely to have occluded blood vessels. Stressed animals release catecholamines that shift blood distribution towards central large vessels and it is proposed that a higher proportion of blood loss is required before insensibility is achieved.

Stress (fear) has the potential to spread through a group of animals in an abattoir with an increased tendency for stressed animals to balk, which may lead to staff becoming frustrated and employing greater force with balking animals.

Pre-slaughter stress can have a significant negative effect on meat quality. For the project, the time when an animal’s nose entered the restraint and when its neck was cut was recorded as the “restraint to cut interval”. 

The two abattoirs had different chute (corridor) arrangements with one curved and the other straight before the restraint.

Observations on animal and human behaviour occurred as “events” at “zones” (locations). Human interactions were recorded as noise (encouraging the animal to move), hand slap to the animal, stick (physical contact), active electric prod and door (closed on the back of the animal).

Twelve aspects of animal behaviour recorded included movement, slips and falls, vocalising, balking, stopping and turning.

There were differences between the two abattoirs. In abattoir A, 92% of animals received at least one electric prod with 32% in abattoir B. It was noticeable that animals were less likely to move forward, due to the prod, the closer they were to the restraint.

Balking on entering the restraint occurred in 13% and 18% of the animals. The restraint to cut interval was 31+/-1 seconds in A and 35+/-5 seconds in B, but there was no statistical association between delays to the interval in either abattoir. 

Once in the upright restraint, 16% of animals struggled and 17% vocalised in A whereas 4% struggled and 0% vocalised in B. Differences in the pressure exerted by the restraint may account for the vocalisation readings. 

Interestingly, cattle immediately following an animal that was highly reactive did not appear to behave differently. The author recognises that this observation differs from other work and may be due to the size of the data set.

This study highlights the different behaviour of cattle and operators as the animals move along the corridor and that greater stress-related activity takes place as the animals approach the restraint. The project received an external scholarship from the Humane Slaughter Association. 

Tail docking and castration of lambs 

Two studies, involving the commercial flock of mainly mules at the Royal Veterinary College, have advanced knowledge about the effects of tail docking and castration of lambs.

Richard Pizzey collected data on twin lambs that were castrated and tail-docked using rubber rings, applied by a “competent operator”. Elastration without an anaesthetic is only permitted during the first week of life and the lambs included in the study were from 24 to 48 hours of age.

The behaviour of the lambs and the impact on liveweight gain were monitored over a 10-week period, commencing at 30 minutes after the procedure(s). Lambs were weighed at 24 and 48 hours, after castration and tail docking, then at regular intervals. These lambs were effectively controls for a larger study and established a baseline as to how painful the procedures are and to identify which behaviours could be used as accurate indicators of pain.

A pain assessment system was developed by students and staff that included standing posture, lying position, tail wagging and gait, kicking out or stamping, movement around the pen and closeness to their dam.

Vocalisation was noted for volume, frequency and pain-related. Each lamb was scored from one to 10 as to how much pain the operator judged them to be in.

Two hours prior to the procedures the lambs were handled brie y and weighed. At one hour before elastration, pain scores were at their lowest, increasing to a maximum 30 minutes after the procedure(s). Male lambs had significantly higher pain scores at 30 minutes and one hour post-elastration, pain scores in both sexes reduced gradually until both sexes returned similar figures at eight hours.

Male lambs showed general abnormal behaviour from all measurements initially with a decline in kicking/stamping and tail wagging after two hours.

Lying position was noticeably affected with a sharp fall in frequency over four hours and a steady decline thereafter.

At one hour, 72% of males and 15% of females showed abnormal lying positions and 91% of female lambs were deemed to be close to their mothers compared to 21% of males.

The author concludes that “an abnormal lying position is a strong indicator in neonatal lambs”. However, no statistical difference was found in daily liveweight gain between the males and females, suggesting that acute pain over the first 48 hours does not influence growth rates.

Recognising that elastration is a common but painful procedure, Zoe Logan investigated the benefits of administering 0.5mg/kg meloxicam subcutaneously two hours before carrying out the procedure(s).

The hypothesis was that meloxicam would reduce pain-associated behaviours and increase weight gain in lambs. There are no drugs licensed for pain relief in lambs, although the Farm Animal Welfare Council has recommended that pain relief should be given after a practical method of administration has been demonstrated in the literature.

The author recognises many of the difficulties and accuracies with the study model. The three observers followed the same lambs to limit bias, for example slight statue standing or arched back, but standing could be an indication of pain or just standing still.

Lambs in the treated group tended to drink more than the controls (standing). In order to standardise pain scores, different people could score the same video, but that was outside the project scope.

Weather conditions can influence behaviour with more animals lying in cold conditions and a temperature- controlled environment would eliminate this possible discrepancy.

No difference was seen in weight gain that could indicate a better overall productivity for the farm if they administered meloxicam. The product (5ml) administered around the neck of the scrotum did not cause any reported side-effects in any individuals.

Behaviour of treated lambs was noticeably easier at 15 minutes after the procedure(s) but not able to be seen 15 minutes later.

Treated lambs suckled more quickly than controls. The lambs for the project were in a shed and it is suggested that lambs in a eld might bene t more from the relief from pain.

The author concludes that a higher dose of meloxicam (Boehringer Ingelheim UK) @1mg/ kg subcutaneously or orally may be worthwhile, two hours before tail docking or castration by elastration.