Highlights of what stakeholders need to know about the scientific knowledge that has supported the new Code of Practice for the Care and Handling of Sheep

The process of Code of Practice development is coordinated by the National Farm Animal Care Council (NFACC), the lead national organization for farm animal care in Canada. NFACC brings together farmers and other agriculture and food sector representatives, animal welfare groups, enforcement and government under a collective decision-making model for advancing farm animal welfare. 

For all stakeholders, an important part of understanding the knowledge basis that underlies the Sheep Code is to understand the findings from the Scientific Committee review, which played a vital supporting role in the Code development process.

This Executive Summary: The Science of the Sheep Code is designed to help deliver this knowledge. It provides highlights of key information from the Scientific Committee report on priority welfare issues.

The complete Scientific Committee review report, along with more information on all aspects of the Sheep Code and the Code development process, is available at www.nfacc.ca/codes-of-practice/sheep.

Executive Summary: The Science of the Sheep Code

Seven key areas of knowledge

These topic areas were identified as key issues relevant to sheep welfare that would benefit from a review of the scientific literature

Stressful handling and management procedures

One important aspect of the welfare of sheep is to find ways to minimize the stress these animals experience as a result of routine handling and management procedures.

What the science says. The science indicates that while many of common procedures can be stressful to sheep, there is substantial opportunity for the development of improved strategies to mitigate this stress response.

For example, research indicates that sheep are sensitive to the suddenness, unfamiliarity and predictability of their environment and form expectations of events and consequences of these events, all of which carries implications for stress response and overall welfare.

Examples of ways to reduce stress responses include strategies that involve:

• Using positive reinforcement during handling or when undertaking a procedure
• Familiarizing or habituating the sheep to the handling area
• Providing some ‘gentling’ with humans – for example, repeated exposure to a human standing next to the sheep and talking and patting it reduces fear when encountering humans for different procedures

Accelerated lambing

Lambing traditionally occurs once per year in the spring. However, a growing number of producers have adopted accelerated lambing systems that facilitate lambing more frequently – for example, every seven or eight months, rather than once per year.

What the science says. The literature identifies several potentially negative effects of accelerated lambing on the welfare of both ewes and lambs. However, these are simply ‘potential’ negatives and more research is needed to support definitive conclusions.

Three potential welfare concerns stood out overall. The first, for lambs, is the potential for lower birth weight in autumn or winter compared with those born during traditional spring lambing. The second, for ewes, is reduced time for post-partum and post-lactation recovery. A third primary concern relevant to both ewes and lambs is that accelerated lambing can require changes to health control measures to minimize the risk of disease.

But due in part to a lack of research the bottom line is there is little scientific evidence currently that has demonstrated sheep are worse off from a welfare perspective in an accelerated system compared with a traditional one.

The committee strongly emphasizes the need for research that targets a comprehensive, comparative evaluation of the welfare implications of both systems. However in the meantime an analysis of the potential welfare issues associated with accelerated systems suggests that many of these issues can be avoided with a higher level of management.

Methods of on-farm euthanasia

On-farm euthanasia may at times be necessary to prevent animal suffering.

What the science says. When evaluating the potential methods of euthanasia, the key was to identify methods that were quick, caused minimal stress or pain and resulted in rapid loss of consciousness and death without the animal regaining consciousness.

When implemented properly, the literature indicated that the use of a penetrative captive bolt followed by exsanguination (i.e. bleeding out) or pithing met these criteria. A captive bolt stun is designed only to stun a sheep and will not necessarily kill the sheep. Used properly it can result in immediate loss of consciousness; however, accurate placement of the stunner on the head can be difficult.

Importantly, the science indicates that use of exsanguination alone without prior stunning carries potential for pain and distress while not meeting the requirement of delivering immediate loss of consciousness.

As gunshot is not a normal method of slaughtering sheep for human consumption there was less research available than for captive bolt stunning. However, the limited research suggested that if the gunshot caused sufficient brain damage, there would be rapid loss of consciousness and death without the animal regaining consciousness.

Although the literature showed that blunt trauma can cause extensive brain damage to lambs, no reports were found that evaluated the effectiveness of blunt trauma as a method of euthanasia for young lambs.

Flooring types

Flooring type and condition is another important factor that has implications for the welfare of sheep. Though these animals are often raised in extensive pasture environments or in dry lots, in some situations and environments they are kept indoors during the winter or year round.

Different types of flooring may be used in these buildings, and certain types of welfare issues may arise that are related to these flooring options.

What the science says. There was limited research on the effects of flooring on sheep welfare. Wet and warm conditions compared with dry and warm or wet and cold conditions can increase the risk of foot rot. Hard surfaces can cause claw wear and predispose to arthritis compared with softer surfaces. There was insufficient research on the effects of floor type on the risks of teat injury and mastitis in ewes to provide reliable information on this topic.

Neonatal care up to and including weaning

The period of time from birth to weaning is a critical one to the health and welfare of ewes and lambs that presents unique challenges. Chief among these are the potential for dystocia (difficulty at birth), risks to neonatal survival, detriments associated with artificial rearing, and the process of weaning itself.

What the science says 

Dystocia. Dystocia increases the risk of lamb mortality and can delay the performance of important behaviours, such as suckling. The risk of dystocia is affected by factors such as, breed, lamb weight and number of lambs.

Neonatal survival. Lamb mortality rates vary greatly due to the broad spectrum of scale and approaches among production systems and the many factors involved.

In extensive systems, the majority of lamb deaths are attributed to dystocia from prolonged or difficult birth or the starvation-mismothering-exposure complex.

Colostrum intake provides energy that makes newborn lambs less susceptible to mortality during cold conditions and if ingested within the first 24 hours the absorption of antibodies across the intestine can decrease the risk of subsequent mortality from infectious diseases.

Optimal birth weight increases the chances of survival. Small lambs are often weaker at birth, reducing their ability to obtain adequate milk from the dam and predisposing them to disease and starvation. Although in heavy lambs, the risk of death within the first 24 hours is higher due to the higher risk of experiencing consequences from dystocia, subsequent risk of mortality is lower than in smaller lambs.

Artificial rearing. There has been relatively little research on the welfare implications of artificial rearing. There is some evidence that it is beneficial for lambs to be reared by their dam so that they receive the advantages of maternal behaviour and normal suckling.

When lambs are separated from their mother, they can experience emotional stress.

Weaning. Natural weaning generally takes place slowly, with the ewe completely preventing the lamb from sucking between 125 and 160 days of age, with some variation depending on the level of protein in the diet and the breed of sheep. This natural weaning off of milk is not generally accompanied by immediate social separation which is a part of artificial weaning.

The available science generally supports weaning closer to the timeframe of the natural process as preferable from a welfare perspective. For example, while abrupt weaning at any age before natural weaning is likely to cause stress, the stress responses of lambs weaned at 50 days of age are higher than those of lambs weaned at 100 days of age.

The natural bond between the ewe and the lamb weakens as the lamb ages, suggesting that later weaning poses less stress on the ewe and the lamb, but minimal research has been conducted to support this. Weaning at an age of 28 days or earlier requires specific attention to the diet of the lamb as the rumen has not fully developed.

Painful procedures

The science review covered several routine procedures which potentially cause pain in sheep, with a major specific focus on tail docking, castration, and ear tagging.

What the science says. A fundamental challenge is how to recognize and evaluate pain in sheep. While it is impossible to directly measure what the animal is experiencing, research has contributed to the identification of a number of physiological and behavioral responses that provide reliable indirect evidence. Caution is required when utilising the interpretations of the relative severity of pain from different methods of tail docking and/or castration as conclusions can only be tentative.

There is no evidence that younger lambs experience less pain following either tail docking and/or castration than older lamb.

Tail docking. The four main methods for tail docking include hot iron, rubber ring, rubber ring combined with clamp, and surgical method. The evidence indicates that each of these methods is painful and shows that some of this pain can be reduced by the administration of local anesthetics and/or analgesics.

The main conclusions of the review of the extensive scientific literature on tail docking were:

Rubber ring method

• Physiological and behavioural evidence suggests that tail docking using a rubber ring is acutely painful. There is some pathological evidence that suggests that some pain might persist for several months.
• Tail docking using a rubber ring alone appears to be more painful than tail docking using either rubber ring combined with a clamp or a hot iron alone.
• Tail docking using a rubber ring might be more painful than tail docking using a surgical method, but some of the evidence is contradictory.
• Use of local anesthesia at the site before the rubber ring is applied can reduce the signs of acute pain.
• The non-steroidal anti-inflammatory drug (NSAID) diclofenac can be beneficial in that it reduces the plasma cortisol response, but does not reduce behavioural signs of pain and is not as effective as local anesthesia.

Combined ring and clamp method

• Physiological and behavioural evidence suggests that tail docking using a combined rubber ring and clamp method is acutely painful.
• Tail docking using a combined rubber ring and clamp method appears to be less painful than tail docking using only a rubber ring.
• Tail docking using a combined rubber ring and clamp method might be more painful than tail docking using surgery.

Surgical method

• Physiological evidence suggests that tail docking using surgery, i.e. cutting the tail off using a knife or scalpel - is acutely painful.
• Tail docking using surgery might be less painful than tail docking using a rubber ring, but some of the evidence is contradictory.

Hot iron method

• Other methods of tail docking e.g. rubber ring or surgery have acute physiological and behavioural responses that are not as apparent after docking using a hot iron.

If there is a risk of flystrike, some studies have shown that tail docking can reduce the risk of flystrike to the tail.

If the tail is removed completely (i.e. leaving three or fewer coccygeal vertebrae) there is an increased risk of problems compared with not tail docking. Lambs tail docked at the fourth tail joint show fewer problems than those that have been docked to leave a shorter tail length.

Castration. The three main methods of castration are rubber ring, clamp (Burdizzo) and surgical. The evidence indicates that each of these methods is painful and shows that some of this pain can be reduced by the administration of local anesthetics and/or analgesics.

The main conclusions of the review of the extensive scientific literature on castration were:

Rubber ring method

• There is a marked physiological and behavioural response to rubber ring castration that is indicative of acute pain.
• Local anesthesia injected into the scrotal neck and cord or the testis can reduce this response.
• The non-steroidal anti-inflammatory drug (NSAID) flunixin can reduce this response.
• Until the scrotum falls off after about 4 weeks, it remains swollen and appears to cause behavioural signs of discomfort.

Clamp (Burdizzo) method

• There is a physiological and behavioural response to clamp castration that is indicative of acute pain.
• Local anesthesia injected into the scrotal neck and cord can reduce this response.

Clamp and ring method

• There is a physiological and behavioural response to clamp castration that is indicative of acute pain.
• Local anesthesia injected into the scrotal neck and cord or the testis can reduce this response.
• The response to the combined clamp and ring method appears to be less than castration by rubber ring alone, but greater than castration by clamp alone.

Surgical method

• There is a marked physiological and behavioural response to surgical castration that is indicative of acute pain.

Castration may not be necessary in lambs slaughtered at or before puberty.

Ear tagging. In Canada, all sheep must be identified with an approved ear tag before leaving the farm of origin.

Other than vocalization and a shake of the head in some lambs, any transient pain associated with the insertion of an ear tag is too small to be measured using the methods used to detect pain due to other procedures, such as tail docking and castration. However, there is often an inflammatory reaction for at least six weeks.

Snow as a water source

The review also examined the question of whether unrestricted access to snow is adequate as a sole source of water for sheep.

What the science says. The quality and quantity of available water can have a significant impact on the welfare of sheep. Sheep have efficient physiological mechanisms to deal with periods of water restriction and are able to withstand higher levels of water deprivation than humans. However, their welfare will deteriorate if they do not have adequate water intake.

There is insufficient scientific information to make any firm conclusions on the welfare implications of providing snow as the only source of water for sheep. The limited information available did not indicate any severe difficulties when only snow was provided as a water source However, further studies are required to evaluate the welfare implications in a range of conditions.

View the Scientific Committee report for complete information

This Executive Summary: The Science of the Sheep Code highlights key findings from the Sheep Code Scientific Committee Report. The complete report is available on the NFACC website at www.nfacc.ca/resources/codes-of-practice/sheep/Sheep_SC_report_Oct_2012.pdf.

The work of the Scientific Committee supports but did not determine the final wording of specific requirements and recommendations within a Code of Practice.

Code of Practice updates initiated from 2010 to 2013 are part of the project: Addressing Domestic and International Market Expectations Relative to Farm Animal Welfare – a project made possible through Agriculture and Agri-Food Canada’s Agricultural Flexibility Fund, as part of Canada’s Economic Action Plan.