Location and subjects

Geographical location of the area studied

The study region is located within the temperate zone characteristic of Mexican sierras, with rains in summer, and an average annual temperature range of 18° to 24°C.⁸ It is the most economically important region where the two systems of pig production can be found.

Seven rustic production units (UPr) were evaluated along with six technified production units (UPt), all representative of the pig production system located in the states of Hidalgo (2 UPr, 1 UPt), Tlaxcala (4 UPr, 2 UPt), Morelos (3 UPt), and Mexico City (1 UPr). All of these states are located in the Central Region of Mexico (Figure 1). Farms were selected through the Ministry of Agriculture and Livestock’s (SAGARPA) census of pig producers in the country, including small producers, according to the number of animals in the farms.

Figure 1 States where rustic and technified production units were evaluated in the Central Region of Mexico (Elaborated from Google data). 

Characteristics of the production units selected

I. Rustic production units.

All the farms had a person in charge of the unit and included a range of between 10 to 50 breeding sows, with 100 to 500 animals in production. The main objective of keeping pigs in this type of production was commercial; however, some breeders said they also used the animals to complement the family diet as well as a resource in case of financial emergencies. It was common for production units to be inhabited by families (the owner or employees) and contain other associated species such as poultry, rabbits, sheep, and cows. Production units were in charge of women and men that took care of the animals and only occasionally hired workers. The production systems in most of the farms were diversified (Figure 2). Very few of the producers used commercial balanced feed as the only source of nutrients; the great majority used forage and oilseeds typical of their regions as well as leftovers. There were large differences in the types of shelter with respect to installation design and the materials used. In the service and gestation areas, as well as in the maternity area, all the sows were kept in pens.

Figure 2 Scheme of the rustic production system, which shows the three systems that comprise it (livestock, agriculture and forestry) and the interactions that exist between them. 

II. Technified production units.

All the farms had a person in charge of the unit and included a herd of 100 to 500 breeding sows, resulting in approximately 1000 and 5000 animals in production. The main objective of keeping pigs was a commercial venture and only one producer said that they used the animals as part of the family diet. Most of the production units were not in the same place as the households of the producers and/or workers, and only one producer kept sheep as an associated species. Except for one producer, all farms hired workers who were in charge of animal care. The lands close to the pig rearing systems were intended for the production of maize, sorghum, and aromatic herbs which were sold locally and/or exported (Figure 3). The feeding system in this type of production was based on balanced feed acquired commercially or which the producers prepared themselves. The installations in which the animals were housed had nearly identical designs, including materials and additional features. In the service and gestation areas as well as the maternity areas, all the sows were housed in commercial pens designed especially for the corresponding area.

Figure 3 Scheme of the technified production system, which shows the two systems, livestock and agriculture, and the interactions that exist between them. 

Procedure for data collection

Statistic analysis

The IBM SPSS Statistics 21 program ¹⁰ was used to analyse animal welfare indicators. The criteria Absence of prolonged hunger, Absence of prolonged thirst, Comfort at rest, Thermal comfort, Ease of movement, Absence of wounds, Absence of diseases, Absence of pain induced by management procedures, Expression of social behaviours, Expression of other behaviours, Good human-animal relationship, and Positive emotional states, evaluated in sows and piglets in farms (maternity) and in farm pigs (fattening) were expressed in proportion; that is, the percentage of animals exhibiting the characteristic to be evaluated was expressed in proportion to the total number of animals sampled during the evaluation. This evaluation was done for each criterion. According to the indications of the WQ protocols,⁹ when the number of sows was ≤6, all of the sows were selected. When the number of sows was ≥6 but ≤100, 10 animals in each of the three stages of pregnancy (early, mid-, and late gestation) were identified for the evaluation. Alternatively, if the number of sows was ≥100, the selection was randomized following the WQ protocols criteria.⁹ Likewise, when assessing growing pigs, whenever possible, 150 pigs from 10 different pens/groups (15 pigs per pen/group) were evaluated. If there were less than 10 pens/groups, the number of pigs inspected inside each pen/group had to increase until reaching a total of 150 animals (or the total number of animals in fattening, in the case of smaller farms). The method was applied at three different stages of the growing/fattening period.⁹ The Mann-Whitney test was used to establish whether there were significant differences between the criteria evaluated in the animals in the rustic and technified production units. A difference was considered statistically significant when its P value was less than 0.05.¹¹

Integration of results

Once all the measurements were carried out in the production units, a bottom-up approach was followed to produce an overall assessment of animal welfare on the particular production unit: first the data collected was combined to calculate criterion-scores through decision trees, proportions, alarm thresholds, and nonlinear functions (I-spline); then criterion-scores were combined to calculate principle-scores, using Choquet integrals; and finally the production unit was assigned to one welfare category according to the principle-scores obtained.⁹

Each welfare category was defined through “aspiration values”. They represented the goal that the farm should try to achieve to be assigned to a given category. It was important that the final classification reflects what can realistically be achieved in practice. Therefore, a farm is considered “excellent” if it scores more than 55 on all principles and more than 80 on two of them, while it was considered “enhanced” if it scores more than 20 on all principles and more than 55 on two of them. Farms with “acceptable” levels of animal welfare score more than 10 on all principles and more than 20 on three of them. Farms that do not reach these minimum standards were not classified.⁹

Comparison of animal welfare indicators between rustic and technified production units

Table 3 shows the frequencies of the means of the criteria evaluated during the application of the Welfare Quality protocol in animals in rustic and technified production units. The frequency of criteria corresponding to the principle of Good health (Absence of wounds, Absence of diseases and Absence of pain induced by management procedures) and the criterion Social behaviour expression (Appropriate behaviour principle) was significantly higher in animals housed in rustic production units (U = 5, P < 0.05; U = 2.5, P < 0.01; U = 9, P ≤ 0.05, and U = 1, P < 0.01, respectively), whereas the frequency corresponding to the positive emotional states criterion, belonging to the appropriate behaviour principle, was significantly higher in the animals of the technified production units (U = 6, P < 0.05). On the other hand, there were no significant differences between the animals of the rustic and technified production units in the criteria included in the principles Good feeding and Good housing, nor in the criteria Expression of other behaviours and Good human-animal relationship in the principle of Appropriate behaviour.

One of the first interesting results was related to the health of the animals (absence of wounds, absence of diseases and pain induced by management procedures), where the frequency of these criteria was significantly higher in animals housed in rustic production units. In general, when questioning the producers about which diseases were the most common on their farms, most responded with digestive and respiratory problems, which coincide with findings described in the work of Losada.¹² However, it should be noted that the incidence of other productive diseases (Circovirosis, Mycoplasmosis, PRRS, Parvovirosis, Leptospirosis, Erisipelosis) was higher in technified systems. The relationship between the density of animals in confinement and their health has been examined by several researchers.^13-16 With the industrialization of agriculture, people began to use “technological sanders” -such as antibiotics, vaccines, bacterins, hormones, air-handling systems, and other technological innovations- that allowed for intensive production. In a traditional husbandry system, these practices could have reduced farm productivity, but in the technified system, they increased farm productivity from an economic standpoint.¹⁷

In relation to the presence of wounds in the animals, one of the main causes was related to the movement of piglets after weaning -and social regrouping. It is common to move the animals out of the group where they were raised, either for productive or breeding reasons, which leads to social instability within the group.¹⁴ The exposure to new and unstable social situations can induce fear, which, when combined with no possibilities of escape, may result in intense fighting.^14,18,19 Studies demonstrate that pigs can discriminate between familiar and unfamiliar individuals through olfactory, visual, and probably auditory cues and that environmental pollutants (e.g., high levels of ammonia) may alter preferences for approaching familiar or unfamiliar individuals.^19-22 In established groups, one important way of ensuring that individuals do not constrain the behaviour of fellow group members or adversely affect their welfare in other ways is to provide animals with opportunities to avoid each other.¹⁴ Some researchers suggest the use of visual barriers to reduce aggression, and for pigs specifically, pop-holes in which the head can be hidden appear to be effective in terminating or avoiding aggressive attacks.^19,23,24

With regards to other health indicators, specifically the absence of pain induced by management procedures, it was notable that this factor was practically the same between rustic and technified systems. A recurring practice in this type of system (apart from castration and teeth clipping) was the tail docking of piglets. Pigs have always had a tendency to bite each other’s tails. Under extensive conditions, pigs have the space to get away from one another: it is only in confinement that tail-biting became a serious problem.^16,25-27 The response of the producer has been to amputate the distal half of the tail, a surgical solution to a “human induced” problem. It has been suggested by several researchers that tail-biting can be prevented by making changes in housing, changes in the animals’ diet (mainly protein and mineral balance), and providing substrates (straw, compost, newspaper, ties), as well as eliminating atmospherically uncomfortable factors (high levels of ammonia, CO2, humidity, or low barometric pressure).^24,25,27-31 Boredom is also a relevant factor in these circumstances. In rustic systems, where animal density is lower, sometimes rims, chains, or alfalfa branches are placed within enclosures as sources of entertainment for the animals, a situation which technified systems “cannot afford”. The concept of “modernity” in pig production becomes intolerant in this regard, since the presence of distractors for animals is rarely considered by producers.

With reference to the expression of social behaviour, the animals in the technified systems obtained a lower rating in this indicator because they exhibited a greater amount of socio-negative behaviours, including aggression to conspecifics. Limited access to resources along with high animal densities gives rise to such competitive situations.^14,16,24) In the farm environment, group size and density are predetermined to maximize economic returns (exogenous control of group size),¹⁴ which implies that social behaviour of animals has to adapt to the density established by the producer.¹⁹ In both evaluated systems the groups were exogenous, formed by the needs established by the producer, who in the majority of the cases sought homogeneity in the size of the animals. In the restricted farm environment, group size cannot be self-regulated because animals have no opportunities to leave if attacked by a group member. The impossibility of leaving the group creates a situation that increases the potential for costly aggressive interactions and may favour despotic behaviour by some individuals.^19,32 Provision of opportunities to hide and retreat from aggressive conspecifics may be a wise management strategy to reduce the negative consequences of aggressive interactions.¹⁴ Finally, it should be remembered that Vanhonacker et al.³³ mention that social concern about animal density as well as pen size is imperative within the overall picture of animal welfare on farms.

Another relevant aspect was related to the positive emotional states of the animals. This criterion presents a different measurement scale: the lower the score obtained, the higher the final grade will be. The frequency of this indicator was significantly higher in the animals of the technified production units, which, as mentioned above, is interpreted as a lower total score. The affective states of animals play a central role in our understanding of animal welfare.³⁴ In recent years, evidence of the cognitive and emotional capacities of animals has grown, and it has become increasingly clear that they are conscious, experiential individuals.³⁵ In this context, common sense present in social ethics does not doubt that animals are capable of being bored ³⁶ - a clear example is the criticism of sow stalls - and production systems are judged according to this knowledge.²⁵ Scientific ideology has rejected such evaluations as “anthropomorphic”, however, as Rollin ²⁵ and Balcombe ³⁵ point out, a precise and scientific meaning can be given to terms such as “bored” when applied to animals. On the other hand, many of the important questions about animal welfare arise when people, based on their daily understanding of animals, show concern about their affective states.^33,37 Finally, there is an emerging view that welfare should be more than just the absence of suffering (pain-avoider/pleasure-seeker).^35,38 Balcombe ³⁵ points out that when capacity for pleasure is included, the arguments for welfare become stronger, as Regan ³⁹ mentioned “lives with pleasurable moments are lives of intrinsic value”.

Clearly, the most difficult challenge for the livestock sector is to satisfy the behavioural needs (psychological/biological) of animals in technified systems. However, it should be noted that this process is not starting from zero. Many countries have been conducting research on alternative production systems in recent years.^2,40 In addition, the need for rustic systems to stop considering technified production as the “model to follow” should be re-examined. The increase in consumer demand for animal products derived from an “environmentally-friendly” production system (including animal welfare) has put pressure on production chains in order to certify or improve the welfare status of animals.^41-43 Thus, recent concepts of sustainability in livestock production have paid great attention to animal welfare issues.^{15,33,42,44-47} Animal welfare problems have become a compelling reason for the public to perceive some systems as unacceptable and therefore unsustainable unless some modification is made. In this context, it is clear that animal welfare is becoming a strong motivating factor for members of the public who demand a change on the part of producers, companies, and governments.