Assessing on farm pig welfare

Animal welfare can be defined in a number of different ways, but there is a growing consensus that whatever the definition, it has to include three elements: the emotional state of the animal, its biological functioning and its ability to show normal patterns of behaviour (Manteca, Velarde & Jones, 2009). These three elements are by no means contradictory; in fact they are closely interrelated. The Five Freedoms developed by the Farm Animal Welfare Council (1992) combine elements from the three approaches to welfare explained above and are a very useful framework to identify the main welfare problems. These freedoms, which represent ideal states rather than actual standards for animal welfare, include: freedom from hunger and thirst, freedom from discomfort, freedom from pain, injury and disease, freedom to express normal behaviour, and freedom from fear and distress.

The objectives of this paper are to discuss some of the main welfare problems in intensive pig production and to introduce the Welfare Quality® protocol for pigs. 

Welfare Quality® (www.welfarequality.net) was an integrated research project co-financed by the European Commission, which ran from May 2004 to December 2009. The project was designed to integrate farm animal welfare into the food chain and the main aims were to develop a standardised system for assessing the welfare of animals kept on farms that are scientifically sound and feasible (Blokhuis, Jones, Geers, Miele & Veissier, 2003).

The awareness that welfare is multidimensional and that its overall assessment requires a multicriteria evaluation resulted in the decision to base the Welfare Quality® assessment system on four main principles according to how they are experienced by animals: good feeding, good housing, good health, and appropriate behaviour (Blokhuis Keeling, Gavinelli & Serratosa, 2008). Within these principles, the project highlighted twelve distinct but complementary animal welfare criteria. These twelve animal welfare criteria provide a very useful framework for understanding the components of animal welfare.

1. Good feeding includes two criteria: absence of prolonged hunger and absence of prolonged thirst. Hunger may result from malnutrition, undernutrition or both. Malnutrition occurs when nutrients are not balanced, whereas undernutrition reflects insufficient supply. Malnutrition and undernutrition cause stress and, if sufficiently prolonged or severe, this can lead to debilitation, loss of body condition, immunosuppression and disease. Chronic hunger in pregnant sows is the main welfare problem related to this criterion.

Prolonged thirst causes stress and, if long-lasting or severe, leads to debilitation, loss of body condition and disease. For example, low water intake in pregnant sows may cause urinary infections. Thirst also reduces food intake which, in turn, may lead to the welfare problems associated with prolonged hunger. Prolonged thirst can occur when animals are given water of poor quality or when drinking facilities are insufficient or inadequate, mainly due to neglect or poor husbandry. The latter condition is exacerbated when there is competition with conspecifics.

2. Good housing includes comfort around resting, thermal comfort and ease of movement. Lack of comfort around resting may be a consequence of an excessive stocking density or inadequate housing facilities. To satisfy its need for comfort around resting, each animal should have enough space to stand up, lie down and turn around. For instance, pigs prefer to separate their dunging area from their lying area. If the stocking density is too high, some pigs may have to lie in the dunging area, among faeces and urine.

Farm animals are homoeothermic, which means they are able to maintain a relatively constant deep body temperature that differs from the environmental temperature within certain limits. A relatively constant deep body temperature means that heat production and heat loss are equal. Lower environmental temperature leads to higher heat losses, which have to be compensated by a higher heat production. Temperatures which are too low or too high cause cold and heat stress, respectively. Cold stress is a particular hazard for newborn animals and, together with starvation, plays an important role in neonatal mortality in piglets (Mellor and Stafford, 2004). On the other hand, pigs have great difficulty in losing heat and may therefore suffer heat stress at ambient temperatures close to the upper limit of their thermoneutral zone and at high humidity. Heat stress may result from poor ventilation, inadequate housing and an overly high stocking density.

Ease of movement, i.e. the ability of animals to turn round, get up and lie down has long been considered a basic requisite for good welfare (Brambell Committee, 1965). Too high stocking densities or inadequate design of housing facilities may prevent animals from moving normally. Lack of comfort around resting can be detected by several indicators such as shoulder sores in farrowing sows mainly caused by an inappropriate size of the crates.

3. Good health is an important component of animal welfare and it can be defined as the absence of injuries, disease and pain. These negative states can have many causes, including certain management procedures. Injuries can cause acute and/or chronic pain. Pain is defined as an aversive emotional experience and is therefore a welfare problem. The legs and the feet are the parts of the body that are most frequently injured in farm animals. These injuries interfere with normal behaviour and locomotion, and may have a debilitating effect by preventing the animal from feeding normally. Wounds can become infected and, under some circumstances, may lead to systemic disease. Infectious, systemic diseases secondary to injuries as well as the debilitating effect of some injuries may result in the animals being culled. Fighting with other animals can also cause injury; this is more common when animals are mixed with unacquainted individuals and when animals have to compete for access to feed, water or resting space (Velarde, 2007). Tail-biting is also an important cause of injuries. According to the most widely accepted hypothesis, tail biting is a form of redirected behaviour derived from the thwarting of normal exploratory motivations. It can also derived from situations of competition (e.g. for food and drinkers), frustration and stress (such as thermal stress). Tail-biting is a welfare problem because of the pain and suffering experienced by the bitten animal (not only due to the biting but also to secondary infections), the restlessness caused to the group, and the likely discomfort of the biter animal. As for other behaviour problems in intensive pig production, tail biting is a multi-factorial problem involving both internal and environmental risk factors; these include genetic background, sex, age, health status, diet, feeding management and different characteristics of the pen (SchrØder-Petersen et al., 2004). Some types of tail biting have similar risk factors than vulva biting observed in sows.

Absence of disease is a basic requisite for good welfare. Diseases can cause pain and may interfere with normal behaviour. Chronic diseases often have a debilitating effect on the animal and may lead to it being culled. Some of the diseases that are more relevant from an animal welfare standpoint are called “multifactorial diseases”, meaning that they are caused by the interplay of several factors. Diseases can be classified in five main categories: respiratory (e.g. coughing, sneezing, labour breathing or twisted snouts as symptoms observed on farm or the presence of pneumonia or pleurisy when lungs are evaluated at the slaughterhouse), digestive (i.e. diarrhoea, solid faeces, rectal prolapse), reproductive (such as mastitis, metritis, uterine prolapse), neurological (tremor, splay leg) and those affecting the skin (i.e. mange).

Several management procedures that are routinely carried out in farm animals can cause pain. These include tail docking, castration, teeth clipping and nose ringing in outdoor pigs. The pain associated with these procedures normally lasts a few days, but in some cases such as tail docking, there may additionally originate chronic pain. Usually, castration of male pigs is performed surgically without anaesthesia or post-operative analgesia despite evidence that castration at any age is painful and may have a detrimental influence on health (Prunier at al., 2006).

4. Appropriate behaviour includes the expression of social behaviour, expression of other behaviours, good humananimal relationship and a positive emotional state. All farm species are social animals and as such are strongly motivated to have contact with conspecifics. Disruption of social groups (through mixing of unacquainted animals, for example) may lead to an increase in aggressive behaviour and a reduction in positive social interactions. Mixing of unfamiliar animals (often with a change of physical environment) is a common practice in pig husbandry and often happens at weaning, at the beginning of the growing-finishing period and during transport to slaughter. Mixing of unacquainted pigs has adverse effects on welfare and production, mainly because pigs fight in order to establish dominance relationships. Housing conditions that result in increased competition for resources may increase the number of negative social interactions. This may happen when stocking density is too high or when access to resources is insufficient, for example when feeding space is limited. High stocking densities also increase aggression because the easy escape of attacked individuals is thwarted and may cause the dominance hierarchy to be less successful (Ewbank and Bryant, 1969).

Animals are strongly motivated to perform particular behaviour patterns. This is the case, for example, with exploration, rooting, and nest building in farrowing sows. In some circumstances, the inability to perform such behaviour patterns may cause distress and lead to the development of abnormal behaviours such as tail biting. A poor human-animal relationship results in the animals being fearful of the stockpersons and other humans. Poor stockmanship is considered the main cause of bad human-animal relationships. The term “stockmanship” covers the way that animals are handled, the quality of their daily management and health care, and how well problems other than disease are recognised and solved (Waibingler and Spoolder, 2007).

Fear and anxiety are two emotional states induced by the perception of a danger or a potential danger, respectively, that threaten the integrity of the animal (Boissy, 1995). Fear and anxiety both involve physiological and behavioural changes that prepare the animal to cope with the danger. Although fear and anxiety have not always been clearly differentiated, fear can be operationally defined as states of apprehension focusing on isolated and recognisable dangers while anxieties are diffuse states of tension that magnify the illusion of unseen dangers (Rowan, 1988). General fear becomes a problem particularly when animals encounter new or unexpected stimuli, (e.g. a sudden noise or movement, an unfamiliar animal), or situations, e.g. a new housing facility, transportation. This has important implications for animal housing and management. 

For each one of these criteria potential measures were identified and evaluated for inclusion in the pig welfare assessment on farm based on their validity, reliability and feasibility. Validity was the main criterion used and was defined as the extent to which the measure is meaningful in terms of providing information on the welfare of an animal or a group of animals (Winckler, Capdeville, Gebresenget, Hörning & Roiha, 2003). Validation of the measures was based on scientific bibliographies or on research studies carried out during the project. Only those measures with high validity were selected for the operational protocols. Reliability assessment included: 1) inter-observer reliability, which refers to agreement between two or more observers after they have received reasonable training (Dalmau, Geverink, Van Nuffel, Van Steenbergen, Van Reenen, Hautekiet, Vermeulen, Velarde & Tuyttens, 2010); 2) intra-observer reliability which requires that results are largely the same when the same observer repeats assessments (e.g. using video-clips or pictures); 3) test-retest reliability to assess the robustness of the measure to external factors, such as time of day or weather conditions (i.e. repeated tests with the same subjects yield similar data). This means that results must be representative of the longer-term farm situation and not too sensitive to changes in the farm conditions or the internal states of the animals as long as the situation has not changed significantly. At the same time, a measure should be sensitive enough to detect variations in the welfare state of the animals between farms and across periods. Infrequent welfare problems might result in weak test-retest reliability. Feasibility means the possibility to carry out the protocol under practical conditions. For this purpose, issues such as time or equipment needed to take the measure were taken into account. These requirements excluded some physiological parameters that need experimental equipment (e.g. heart rate recordings) or laboratory analyses as well as complex behavioural tests that could not be integrated into the farm routine (e.g. cortisol analyses and open-field tests, respectively). In terms of the feasibility of the whole assessment protocol, it should be possible for a single observer to carry out a farm assessment during a one-day visit.

Previous monitoring systems and legislation largely rely on examination of inputs, ‘what’ or ‘how much’ of different resources are given to animals. These parameters are easy to define, to measure and have a high inter and intra reliability. However, these measures have often been criticized for potentially low validity due to their indirect nature and complex interactions with other resource and management conditions ( Waiblinger, Knierim & Winckler, 2001). Thus, input measures are a poor guarantee for good animal welfare, as animals may experience the same situation or handling procedure differently depending of their genetic background, temperament, or previous experiences.

Since welfare is a condition of the individual animal, wherever possible, the Welfare Quality assessment system places its emphasis on animal-based measures (also called „outcome? measures) rather than on the resource and management in an attempt to estimate the actual welfare state of the animals. Such physiological, health, performance and behavioural measures have inherent advantages over input measures. The first advantage is clearly that, since welfare is a condition of the animal, outcomes measures are likely to be the most direct reflection of their actual welfare state. It permits to evaluate the welfare by directly observing the animal, regardless of how and where it is kept. Secondly, as it is applicable to all farms, animal-based measures permit to compare the welfare of animals from different farms, and remain more transparent to stakeholders.

In Welfare Quality, resource- or management-based measures were therefore only taken into account to complement the animal-based ones or as a substitute when there were no promising animal-based measures available (Botreau at al., 2007). For example, no valid, reliable and feasible animal based measure was found for the evaluation of prolonged thirst. In this case, it was necessary to include resource based measures as the presence, number, cleanliness and functioning of drinkers. Resource and management based measures can also be used to identify risks to animal welfare and identify causes of poor welfare so that improvement strategies can be implemented.

The measures that met the requirements for validity, reliability and feasibility, were combined and integrated into the welfare assessment protocol. Table 1 shows the final lists of measures included in the ‘operational’ protocols for growing pigs on farm.

An important consideration to increase the repeatability and reliability of the assessment is that the measures should be simple to collect and scored in a way that maximises reliability. . For this purpose, most of the measures are scored according to a three-point scale ranging from 0 to 2. So that a score 0 is awarded where welfare is good, a score 1 is awarded where there has been some compromise on welfare, and a score 2 is awarded where welfare is poor and unacceptable. In some cases a binary (0/2 or Yes/No) or a cardinal scale (e.g. cm or m²) is used.

 

Table 1. Collection of data for growing pigs on farm

 

At the beginning of the visit, general information related to the farm is recorded by means of a questionnaire answered by the farmer as well as by visual inspection. The questionnaire records information on management, prevention of diseases, feeding, hygiene management, temperature regulation, castration routine, euthanasia criteria, and production and mortality records.

In the second stage, the assessment involves collecting data on the animals and the resources. A specific order in which the measures to be taken on farms is provided in the protocol for each animal type. In general, the animal-based assessment starts with measures recorded from outside the pen and by observing the whole group. In sows and growing pigs for example, the measures recorded from outside the pen consist of those related to the positive emotional state criterion (by means of the Qualitative Behavioural Assessment, QBA), the expression of social and other behaviours (by means of a scan sampling), and the presence of stereotypies, respiratory problems (coughing and sneezing), and thermal comfort measures (shivering, panting, huddling). Afterwards, the assessor enters the pen to assess the human– animal relationship and other animal-based measures related to the welfare principles of good feeding, housing, and health. Animals are individually scored for body condition, bursitis, shoulder sores, dirtiness (or presence of manure on the body), wounds on the body, tail biting, vulva lesions, lameness, pumping (heavy and laboured breathing), twisted snouts, rectal prolapse, uterine prolapse, skin condition, constipation, scouring, metritis, mastitis, local infections, tremor, splay leg and hernias. These measures are taken in approximately 30 pregnant sows, in 10 lactating sows and their litters, and/or in 150 growing pigs from 10 different pens. Some measures will require sampling of animals at specific stages of pregnancy (early, mid and late gestation) or at different stages of the growing/fattening period (at the beginning of the period but at least one week after mixing to avoid effects of the hierarchy formation, and at the end when space allowance is lower). The stage of pregnancy or growth are not considered likely to affect other measures. However, ensuring a representative sample simplifies the selection process. On many farms, animals in different stages may be housed within the same building (or even room), and are likely to be distributed equally across the building/room. However, if there are many small pens within a building or room those at either end of the building (and in the middle if necessary) should be selected. On farms where animals at the same biological stage are housed in different buildings it is important to sample animals from all the different types of buildings.

To facilitate the use of the welfare assessment system by third parties, the Welfare Quality project edited a book for pigs with a standardized description of the measures, data collection, sample size, evaluation methodology and the calculation of welfare scores (Welfare Quality, 2009). Once the protocols are generated a critical component to obtain objective and repeatable assessments is their uniform interpretation and application by the assessors, particularly for the animal based parameters assessed by direct observation, so a previous standardized training process is recommended. 

One of the main objectives of the welfare assessment protocols is to be applicable to most farming conditions. This was evaluated through surveys on representative samples of different rearing systems and local conditions (e.g. climate) found in Europe and Latin America. Farms were selected for the survey on the basis of management practices, farm size, and veterinary records.

The protocols were tested on 190 farms (90 for sows and 100 for growing pigs). The sow farms examined used extensive outdoors or indoor husbandry systems with different types of floor, bedding material, and feeding system. Similarly, the sample of farms with growing-finishing pigs included outdoor and indoor units with o without bedding material. It was concluded that many animal-based measures in the Welfare Quality assessment protocols are sufficiently sensitive to show high variability and thereby allow discrimination between the farms (Temple et al., 2011). The mean time taken to perform the full protocol in growing pigs at farm is 6 h and 20 min (± 51 min) per visit, ranging from 5h15 to 9h30 min (Temple et al., 2011). The interview, the only part of the protocol that requires farmer participation, takes approximately 40 min (ranging from 25 to 60 min) depending on the farmer’s level of interest. Furthermore, the time taken to record general information varies according to the size of the farm (as much as 200 min on the largest farm). Farm size and the distance between buildings also affected the time required for QBA, scan sampling of behaviours, and the recording of good feeding, housing, and health measures. The number of animals per pen, the density, the fear level of the animals, the dirtiness of pigs, and the light intensity within the buildings are other factors that might influence the time needed to record feeding, housing, and health measures. 

In general, the protocols developed in Welfare Quality® to assess animal welfare on farm seem to work well and they are feasible. The responses obtained from farmers at the end of a visit have been encouraging. Most were pleasantly surprised that the protocol involved little input from their part in data collection (thus not taking up their time) and that none of the measures were invasive or involved to move animals or. Perhaps even more important was the high level of interest they showed in animal-based parameters as they were usually not provided with this type of information. 

The work on which this article is based was carried out in the context of the Welfare Quality® project which was cofinanced by the European Commission, within the 6th Framework Programme, Contract No FOOD-CT-2004-506508. 

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