- Open Access
Development of pig welfare assessment protocol integrating animal-, environment-, and management-based measures
© Renggaman et al.; licensee BioMed Central. 2014
- Received: 22 August 2014
- Accepted: 20 November 2014
- Published: 9 January 2015
Due to increased interest in animal welfare, there is now a need for a comprehensive assessment protocol to be used in intensive pig farming systems. There are two current welfare assessment protocols for pigs: Welfare Quality® Assessment Protocols (applicable in the Europe Union), that mostly focuses on animal-based measures, and the Swine Welfare Assurance Program (applicable in the United States), that mostly focuses on management- and environment-based measures. In certain cases, however, animal-based measures might not be adequate for properly assessing pig welfare status. Similarly, welfare assessment that relies only on environment- and management-based measures might not represent the actual welfare status of pigs. Therefore, the objective of this paper was to develop a new welfare protocol by integrating animal-, environment-, and management-based measures. The background for selection of certain welfare criteria and modification of the scoring systems from existing welfare assessment protocols are described.
The developed pig welfare assessment protocol consists of 17 criteria that are related to four main principles of welfare (good feeding, good housing, good health, and appropriate behavior). Good feeding, good housing, and good health were assessed using a 3-point scale: 0 (good welfare), 1 (moderate welfare), and 2 (poor welfare). In certain cases, only a 2-point scale was used: 0 (certain condition is present) or 2 (certain condition is absent). Appropriate behavior was assessed by scan sampling of positive and negative social behaviors based on qualitative behavior assessment and human-animal relationship tests.
Modification of the body condition score into a 3-point scale revealed pigs with a moderate body condition (score 1). Moreover, additional criteria such as feed quality confirmed that farms had moderate (score 1) or poor feed quality (score 2), especially those farms located in a high relative humidity region.
The developed protocol can be utilized to assess welfare status in an intensive pig farming system. Although further improvements are still needed, this study is a first step in developing a pig welfare assessment protocol that combines animal-, environment-, and management-based measures.
- Animal welfare
- Environment-based measure
- Pig farming
- Intensive farming system
- Welfare assessment protocol
Animal welfare reflects the wellbeing of an animal and comprises an animal’s physical and mental health. Animal welfare is affected by environmental conditions and innate behavior . In Europe, animal welfare has been used as livestock product quality certification parameter . Importance of animal welfare varies among countries or regions. For example, the high awareness of European consumers regarding the welfare of livestock animals has led to livestock welfare regulations . In contrast, Asian consumers show no or little interest in animal welfare, especially that of livestock animals.
Nevertheless, the development of a welfare assessment protocol in Asian countries such as Republic of Korea is needed to advise farmers in improving the welfare of their livestock. Moreover, a welfare certification scheme to standardize livestock products would assist trade between countries in the same region . There are two current welfare assessment protocols for pigs, Welfare Quality® Assessment Protocols and Swine Welfare Assurance Program (SWAP). Welfare Quality® Assessment Protocols are applicable in the European Union and mostly focuses on animal-based measures . Swine Welfare Assurance Program (SWAP) is applicable in the United States and mostly focuses on environment- and management-based measures . These current pig welfare assessment protocols are not necessary applicable in Asian countries. The main obstacle is the difference in how livestock welfare is viewed among the different regions.
The objective of this paper was to develop a new protocol to assess welfare status of growing and fattening pigs in Asian countries such as Republic of Korea by integrating animal-, management-, and environment-based measures. In certain cases, animal-based measures might not be adequate to properly assess pig welfare status. Similarly, welfare assessment that relies only on environment- and management-based measures might not represent the actual welfare status of the pig. In developing the new protocol, the background for selection of certain welfare criteria and modification of the scoring systems from existing welfare assessment protocols are described. Moreover, the new protocol was validated by assessing the welfare status of two growing pig farms.
The developed welfare assessment protocol was tested at two experimental growing pig farms of Seoul National University, Seoul, Republic of Korea. Both farms were representative of early growing and fattening phases. Both farms were conventional indoor farms on concrete flooring with a partially-slatted floor. Pigs entered the farm with an average weight of 20 kg and were removed for slaughter at an average weight of 110 kg. The growing pigs observed in the present study were handled humanely and did not received any constraint throughout the observation. Welfare quality was assessed by two observers, each of which was responsible for assessing two main principles of animal welfare.
Protocol for growing pigs
Developed measures for welfare assessment of growing pigs on farms
I. Good feeding
1 Absence of prolonged hunger1
Body condition scores
2 Feed quality2
3 Absence of prolonged thirst1
II. Good housing
4 Environmental condition2
Temperature and relative humidity5
5 Ventilation status (air quality)2, 3
Particulate matter and ammonia concentration5
6 Comfort around resting1
Bursitis and manure on the body
7 Thermal comfort1
Shivering, panting, and huddling
8 Ease of movement1
9 Other facility condition3
Conditions of floor, fencing, feeder, and other facilities inside the farm4
III. Good health
10 Absence of injuries1
Lameness, wounds, tail biting
11 Absence of disease1
Coughing, sneezing, pumping, twisted snouts, rectal prolapse, scouring, skin condition, ruptures, and hernia
12 Health management3
Veterinary-client-patient relationship, medical record, and hospital pen4
Number of euthanized animal and euthanasia methods
IV. Appropriate behavior
14 Expression of social behavior1
Negative and positive social behavior
15 Expression of other behavior1
16 Good human animal relationship1
Fear of humans
17 Positive emotional state1
Qualitative behavior assessment
As the first step of the farm survey, general farm information was recorded by interviewing farmers using a previously prepared questionnaire. During the interview, observation methods were explained to get farmers consent. The questionnaire recorded information on mortality rate, total number of pigs in the farm and observation house, total number of pens in the observation house, pen area, ventilation system, average weight of observed pigs, and age of observed pigs. After collecting general farm information, behavioral observations were carried out, followed by evaluation of animal- and environment-based measures related to good feeding, good housing, and good health. Farmers had given their consent prior to the observation.
Measurement of good feeding, good housing, and good health
Developed scoring scale for good feeding, housing, and health
Animal with a good body condition
Animal with moderate body condition
Animal with a poor body condition (lean animals)
Less than 1/3 is clod and there is no smell
More than 1/3 but less than 1/2 is clod and doesn’t smell or less than 1/3 is clod but smells sour
More than half is clod and smells sour
Temperature is appropriate for the pigs
Temperature is inappropriate for the pigs
Ammonia concentration below 50 ppm
Ammonia concentration exceeded 50 ppm
No existence of bursa
One or several small bursa or one medium bursa in same leg
Several medium bursa or one big bursa in same leg
Manure on the body
Less than 20% of body is covered with feces
20 to 50% of body is covered with feces
More than 50% of body is covered with feces
No pigs showing huddling behavior
Less than 20% of pigs show huddling behavior
More than 20% of pigs show huddling behavior
No pigs are panting
Less than 20% of pigs are panting
More than 20% of pigs are panting
No pigs are shivering
Less than 20% of pigs are shivering
More than 20% of pigs are shivering
No facility damage inside the pen
There is facility damage inside the pen
Wounds on body
No wounds on pig body
Wound on any part of pig body
No existence of tail biting
Visible fresh blood on the tail and/or evidence of swelling and infection and/or part of the tail missing
Severely lame or not able to walk
No evidence of labored breathing
Evidence of labored breathing
No liquid manure visible in the pen
Liquid manure visible in the pen
No evidence of twisted snouts
Evidence of twisted snouts
Hernia/ruptures observed in pig
No rectal prolapse
Rectal prolapse observed in pig
Normal skin condition
Pig has inflamed, discolored, or spotted skin
(1) There is an associated veterinarian that visits the farm regularly to check animal health conditions. (2) The veterinarian is readily available to follow up when health problems occur on the farm.
Only one aspect of previous point is fulfilled
None of the previous points are fulfilled
Medication record exists
Medication record does not exist
1. There is capable person with sufficient knowledge to euthanize pigs. 2. The method used is safe for human and animal.
Only one aspect of previous point is fulfilled
None of the previous point is fulfilled
Pigs were individually analyzed for their body condition, bursitis, manure on body, lameness, wounds on body, tail biting, pumping, twisted snouts, rectal prolapse, skin condition, ruptures, and hernia. Huddling, shivering, panting, feed quality, facility condition, and scouring were analyzed at the pen level (Table 2). Huddling, shivering, panting, coughing, and sneezing were observed outside the pens. All other measures were assessed inside the pen in order to better observe the pig body. Manure on the body, skin condition, bursitis, and wounds on body were assessed only on one side of each pig, as a previous study by Courboulay and Foubert  showed that there was no statistical difference between the left and right side of the animal body for these observations.
Measurement of appropriate behavior
Behavior measurement was assessed based on Welfare Quality® Assessment Protocols for growing pigs . Behavior observation included social behavior, exploratory behavior, human-animal relationship, and qualitative behavior assessment.
Social behavior and exploratory behavior were measured five times using scan samplings with 2.5 minute intervals between each scan conducted at three observation points . Each observation point consisted of 20–40 pigs for a total of 60–120 pigs. Exploratory behavior was measured when enrichment material was available in the house and showed that almost all pig houses in Republic of Korea do not use any bedding or enrichment material.
Good human-animal relationship was measured by observing fear of humans. Fear of humans was assessed by entering the pens, walking around the group slowly until returning to the starting point, and then waiting for 30 s. Then surveyor walked around slowly again in the opposite direction. The response was scored as 0 or 2. Zero means that up to 60% of pigs panicked, whereas 2 means more than 60% of pigs showed panic responses . Qualitative behavior assessment was observed at two points for each pig house. The duration of each observation was 10 minutes for a total of 20 minutes for each pig house. There are 20 descriptions of behavior (active, relaxed, fearful, agitated, calm, content, happy, tense, enjoying, frustrated, sociable, bored, playful, distressed, positively occupied, listless, lively, indifferent, irritable, and aimless) that were observed on a minimum to maximum scale. A maximum score means that the behavior was dominant, whereas a minimum score means that there was an absence of the behavior in the observed animals. The total length of the scale is 125 mm long.
General farm information
Farm A reared about 152 pigs that were divided into 15 different pens. For farm A, average pig age and weight were 9 weeks and 24 kg, respectively. Pigs in farm A were in early growing phase, which explains their lower body weight. The pen area was approximately 3.64 m2 with a feeder area of approximately 0.24 m2. This indicates that the available area for pigs was approximately 3.4 m2 in each pen. Farm B reared about 138 pigs that were divided into 30 different pens. For farm B, average pig age and weight were 18 weeks and 80 kg, respectively. Pigs in farm B were in early fattening phase, which explains their medium body weight. The pen area was approximately 4.29 m2 with a feeder area of approximately of 0.37 m2. This indicates that the available area for pigs was approximately 3.92 m2 in each pen. Space allowances in farms A and B were approximately 0.336 and 0.853 m2 per pig, respectively. Pigs in both farms were fed manually once a day. Moreover, cleaning in both farms was done once before pigs were housed.
Measurement of good feeding, good housing, and good health
In intensive farming systems, prevalence of poor body condition (score 2) is very low since pigs are usually fed ad libitum . This often results in a low assessment sensitivity of body condition when using Welfare Quality® Assessment Protocol. Welfare Quality® Assessment Protocol uses a binary scoring system (0 or 2) for body condition, which means it can only differentiate between a very poor body condition and good body condition. Therefore, another scoring method is necessary. The current welfare assessment protocol has a score of 0, 1, or 2 to measure pig body condition, thus allowing easier distinction of good, moderate, or poor body condition, respectively. A new criterion (feed quality) was also introduced for the good feeding principle in the developed welfare assessment protocol. Feed quality analysis was proposed since the climate of Republic of Korea is humid, especially in the summer, which means feed can easily rot. Having a feed condition score provides information on whether or not feed is rotten, which would affect the pig digestive system and result in watery feces (diarrhea).
Microclimate parameter and particulate matter concentration in farm A and farm B during validation of the developed welfare assessment protocol
28.52 ± 0.38
27.35 ± 0.86
Relative Humidity, %
67.69 ± 1.37
79.3 ± 10.2
2.83 ± 2.21
6.35 ± 3.23
129.1 ± 18.71
110.13 ± 20.53
88.9 ± 16.94
73.77 ± 22.98
38.97 ± 3.32
36.17 ± 10.07
22.33 ± 3.13
20.93 ± 5.86
273.6 ± 92.77
287.50 ± 64.52
Ammonia (NH3) is a highly irritating, colorless gas that is produced by microbial degradation of pig urine and the nitrogenous compound fraction of feces, and it is representative of gaseous compounds in pig houses. Moreover, NH3 accumulation inside pig houses is an indicator of ventilation failure. Ammonia was chosen as the determined factor since it can be analyzed on-site. The National Pork Board US  suggested that the NH3 concentration should not exceed 50 ppm. In our results, both pig houses had NH3 concentrations lower than 50 ppm. The average NH3 concentration in pig houses A and B were 2.83 and 6.35 ppm, respectively (Table 3). This result indicates that the ventilation systems were adequate in both houses. Although the NH3 concentration during validation of the developed welfare assessment protocol was quite low, NH3 concentration is still a necessary criterion for welfare assessment since high NH3 levels are known to reduce pig performance (average weight gain and feed efficiency), health, and welfare status [11-13].
Particulate matter (PM) is one of the primary air pollutants in livestock housing and almost completely consists of organic and biological matters derived from feed, skin, livestock hair, bedding material, urine, feces, and microorganisms. PM has several adverse effects, such as affecting health of livestock and transporting infectious diseases (microorganisms and toxic compounds) in pig houses [14,15]. Although there is no threshold for PM concentration inside pig houses, addition of PM as a criterion of welfare assessment needs to be considered since PM concentration is related to respiratory diseases such as lung inflammation, irritation of the respiratory system, and rhinitis. It is known that a PM concentration higher than 3700 μg/m3 increases mortality and pneumonia or pleuritis prevalence in fattening pigs [16,17]. Several PM sizes were analyzed since any PM larger than 10 μm is deposited in the nasal passage, PM between 5 to 10 μm is deposited in the upper respiratory tract, and PM smaller than 5 μm (respirable dust) is deposited in the lower respiratory tract and lungs [14,18]. Thus, each PM size might have different effects on the pig body, which means it is necessary to measure PM sizes in pig houses. The PM concentration at both farms was relatively low (Table 3), indicating no welfare problem related to PM concentration.
Huddling, shivering, and panting are animal-based indicators of thermal comfort . In terms of huddling (Figure 3c) and shivering (Figure 3d), both farms showed good welfare quality based on the lack of huddling or shivering behavior in pigs (score 0). However, about 20% of pens in farm B indicated panting behavior (Figure 3e), which is one way for pigs to dissipate body heat. As explained previously, the room temperature in farm B (27.4°C) was higher than the recommended temperature for growing pigs in the weight range from 68 to 100 kg.
Validation results of developed welfare assessment protocol following good health principles
Wounds on body, %
Tail biting, %
Twisted snouts, %
Rectal prolapse, %
Skin condition, %
Ruptures and hernia, %
Almost all of the pigs experienced tail docking, which made it difficult to differentiate whether or not tail biting had occurred. Tail docking is considered as an effective method of reducing tail biting, although recent studies have shown it to have many disadvantages such as pain sensitization, risk of infection, and ethical considerations . In addition, our category defined tail biting as visible fresh blood on the tail, evidence of swelling and infection, or part of the tail missing. In both farms, most pigs showed reduced tail lengths due to tail docking, so we did not count those cases as tail biting.
In term of diseases, the following scores were measured: mortality rate, coughing, sneezing, pumping, twisted snouts, rectal prolapse, scouring, skin condition, ruptures, and hernias and abscesses. In farm A, only one pig (0.9%) showed evidence of pumping (Table 4), which does not exceed the warning threshold (1.8%). In addition, there was evidence of scouring in 60% of total pens (9/15) in farm A, and the alarm threshold for scouring in our protocol is 15%. Additionally, pens were classified as either with liquid feces or without liquid feces. This classification is not sufficient to differentiate the cause of scouring. To exactly determine the problem, detailed information about factors such as fecal consistency and color are needed. Nevertheless, the presence of scouring only in farm A might be due to the young age of the pigs (about 9-weeks-old), which is an age prone to scouring. Environmental changes in early growing pigs can cause a stress response that in turn affects the incidence and severity of enteric disease . The mortality rates in both farms were low (0.05% in farm A and 0.2% in farm B) with a warning threshold of 2.6%. This result shows that the welfare status of the farms based on mortality rate was good.
Several studies have concluded that lung inflammation can be estimated by calculating frequency of coughing . In farm A, coughing frequency was 0.31 with a warning threshold of 0.15. Therefore, the causes behind coughing should be determined. In farm A (0.04), sneezing was under the threshold value of 0.27. In farm B, both coughing (0.01) and sneezing (0.08) were maintained under threshold values. Therefore, there was no indication of a health problem in farm B.
In terms of health management, the following scores were measured: veterinarian-client-patient relationship and medication records. Both farms had medication records, but they did not confirm any veterinarian-client-patient relationship. Our measurement included two possible situations: (1) The veterinarian has recently seen and is personally acquainted with the keeping and care of the animal(s) via medically appropriate and timely visits to the premises where the animal(s) are kept; (2) The practicing veterinarian is readily available for follow-up in case of adverse reactions or failure of the therapy regimen. Neither of these was fulfilled in either farm. Good health management practices, which include a good veterinarian relationship, is important for maintaining good herd health . Therefore, this parameter can be added to assess the welfare status of pig farms.
In terms of euthanasia, the following scores were measured: euthanized animals and euthanasia methods. Using the protocol, euthanized animals were calculated by comparing the amount of euthanized animals to total deaths. Euthanasia is used only when the animal is suffering a condition that either cannot be cured or is uneconomical to be cured. Further, there are situations in which immediate euthanasia is required as a response to inadequate animal conditions. Therefore, appropriate and timely euthanasia methods are critical for pig welfare . However, in both farms, euthanasia practices were not used. Immediate action should be undertaken to improve animal welfare related to this area. Lastly, both farms had a hospital pen. Further information on the use of these hospital pens could be useful since this protocol only determined whether or not one was available.
Measurement of appropriate behavior
Appropriate behavior assessments focused on social behavior, human-animal relationships, and qualitative behavior. Exploratory behavior was not assessed since there was no enrichment material provided for the growing pigs in the visited farms. A lack of enrichment material such as straw can have many effects. From a behavioral point of view, this can reduce the incidence of behavioral expression in pigs . This absence of any enrichment material is most likely due to a lack of knowledge on behalf of the farmer that an enrichment material increases mental health of pigs or too high production costs.
Animal behavior recorded during observation
Active behavior, %
Social behavior, %
Negative social behavior, %
Positive social behavior, %
Pen with score 2 (show panic response), %
The human-animal relationship (HAR) is important and influences both animal production and welfare . Therefore, this criterion must be measured to assess animal welfare status. Fear of humans is measured to assess welfare since sudden and prolonged fear may severely harm animal welfare and have negative consequences on productivity and product quality . In this study, the HAR in the form of a fear-of-human score was expressed as the percentage of pens with more than 60% of pigs showing a panic response. As shown in Table 5, farms A and B showed scores of 46.67% and 30%, respectively. Fear of humans is a direct reflection of how the pigs are handled. There are also several factors that influence fear of humans, including age, genetic background, and space allowance . The age of growing pigs was 9 weeks in farm A and 18 weeks in farm B. Moreover, space allowances in farms A and B were 0.336 m2/pig and 0.853 m2/pig, respectively. These differences in age and space allowance per pen between the two farms might explain many of the factors above.
Qualitative behavior assessment observation scale expressed in millimeters
This study is a first step in developing a new pig welfare assessment protocol that combines animal-, environment-, and management-based measures. Environment- and management-based measures can help to assess welfare status whenever animal-based measures are difficult. This study also provides an explanation of each criterion in the developed pig welfare assessment protocol.
Assessment showed that some farms have moderate (score 1) or poor feed quality (score 2), especially those farms located in a relatively high humidity region. Specifically, in farm B, 63.33% of pens showed moderate feed quality. Modification of body condition score into a 3-point scale showed that pigs could be divided into three classes: good body condition (score 0), moderate body condition (score 1), and poor body condition (score 2). The prevalence of pigs with moderate body condition in farms A and B were 6.0% and 10.87%, respectively.
The validation results of the two farms show that the developed protocol could be utilized to assess welfare status in an intensive pig farming system. Further improvement of the developed protocol is needed, either by eliminating one or several measurement criteria or by changing the scoring system.
This research was funded by the Ministry of Agriculture, Food, and Rural Affairs (MAFRA) of the Republic of Korea through Project No. 312036–3 and in part by the Ministry of Industry, Energy, and Trade through Project No. 2012302009004.
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