Behavioral and physiological responses of primiparous sows to mixing with older, unfamiliar sows

Welfare of pigs on farm

This scientific opinion focuses on the welfare of pigs on farm, and is based on literature and expert opinion. All pig categories were assessed: gilts and dry sows, farrowing and lactating sows, suckling piglets, weaners, rearing pigs and boars. The most relevant husbandry systems used in Europe are described. For each system, highly relevant welfare consequences were identified, as well as related animal-based measures (ABMs), and hazards leading to the welfare consequences. Moreover, measures to prevent or correct the hazards and/or mitigate the welfare consequences are recommended. Recommendations are also provided on quantitative or qualitative criteria to answer specific questions on the welfare of pigs related to tail biting and related to the European Citizen's Initiative 'End the Cage Age'. For example, the AHAW Panel recommends how to mitigate group stress when dry sows and gilts are grouped immediately after weaning or in early pregnancy. Results of a comparative qualitative assessment suggested that long-stemmed or long-cut straw, hay or haylage is the most suitable material for nest-building. A period of time will be needed for staff and animals to adapt to housing lactating sows and their piglets in farrowing pens (as opposed to crates) before achieving stable welfare outcomes. The panel recommends a minimum available space to the lactating sow to ensure piglet welfare (measured by live-born piglet mortality). Among the main risk factors for tail biting are space allowance, types of flooring, air quality, health status and diet composition, while weaning age was not associated directly with tail biting in later life. The relationship between the availability of space and growth rate, lying behaviour and tail biting in rearing pigs is quantified and presented. Finally, the panel suggests a set of ABMs to use at slaughter for monitoring on-farm welfare of cull sows and rearing pigs.

Effects of parity and litter size on cortisol measures in commercially housed sows and their offspring

Breeding sows are regularly exposed to on-farm stressors throughout the duration of their production period. The impact of such stressors may differ for primi- and multiparous sows, as sows could learn to cope with stressors as they gain experience with them. If parity affects stress in sows, it may also impact their prenatal offspring through differential maternal stress. In addition to parity, litter size is another potential factor involved in stress of sows and piglets. Larger litters may be a source of discomfort for gestating sows, while it can result in intra-uterine growth restriction of piglets. In the current study, we aimed to assess whether parity and litter size affect cortisol measures in breeding sows and their offspring. To do this, we measured salivary cortisol concentrations of 16 primiparous and 16 multiparous sows at three time points: 1) while sows were group housed, 2) after sows were separated from the group prior to moving to the farrowing unit and 3) after handling procedures. In addition, hair cortisol concentration was determined for the sows during late gestation and for their low birth weight (n = 63) and normal birth weight (n = 43) offspring on day 3 after birth, to reflect in-utero cortisol exposure. It was expected that if sows adapt to on-farm stressors, the more experienced, multiparous sows would show decreased stress responses in comparison to primiparous sows. However, we found a comparable acute stress response of primi- and multiparous sows to separation from the group. Handling procedures did not influence sows' salivary cortisol concentrations. Sows' hair cortisol concentration was positively correlated with litter size. Future research is needed to assess whether this finding reflects increased stress in sows carrying larger litters. Parity or litter size did not have a direct effect on their offspring's hair cortisol concentration. Larger litters did have a higher occurrence of low birth weight piglets. For these piglets, females had higher neonatal hair cortisol concentrations than males. Overall, our results indicate that breeding sows do not adapt to all on-farm stressors. In addition, litter size may influence HPA axis activity in both sows and piglets.

Body condition, live weight and success in agonistic encounters in mixed parity groups of sows during gestation

Group housing of gestating sows benefits their welfare by allowing them freedom of movement and the opportunity for social interaction. However, social life could also bring disadvantages for individuals who receive direct aggression or are displaced from the feeder. The aim of this study was to investigate associations between social behaviour, body condition and live weight. Gestating sows (n=298) were investigated on a commercial farm. Sows were housed in mixed parity groups where two single space, ad libitum trough feeders served 12 animals. Sows were weighed, body condition scored and had their back fat layer measured at mixing, 4 weeks after insemination and again before farrowing. Social status was estimated based on the numbers of won and lost agonistic interactions at mixing and at the end of gestation. In addition, tear staining was scored before the farrowing and reproductive performance data were collected. With the aid of video recordings, 100 to 150 interactions per group were observed. Winning percentage at mixing and at the end of gestation were associated (P<0.05) and appeared relatively stable within individuals. Tear staining scores and litter sizes were not associated with winning percentage at the end of gestation. However, live weight, relative weight, body condition and back fat thickness were associated with winning percentage (P<0.05), giving heavier animals an advantage. Low winning percentage related to lower live weight gain, probably due to poorer success in competition for feed. Live weight within a mixed parity group could be used as a proxy measure for social status. Sows with low body condition score and submissive sows might need special attention with regard to group dynamics and housing to alleviate the effects of competition in group housing.

Housing of Cull Sows in the Hours before Transport to the Abattoir-An Initial Description of Sow Behaviour While Waiting in a Transfer Vehicle

In modern pig production, sows are transported by road to abattoirs. For reasons of biosecurity, commercial trucks may have limited access to farms. According to Danish regulations, sows can be kept in stationary transfer vehicles away from the farm for up to two hours before being loaded onto the commercial truck. We aimed to describe the behaviour of sows in transfer vehicles. This preliminary, exploratory study included data from 11 loads from a total of six Danish sow herds. Selection of animals to be slaughtered was done by the farmers. Clinical registrations were made before collection of the sows, after which they (in groups of 7-13) were mixed and moved to the transfer vehicle (median stocking density: 1.2 sow/m²), and driven a short distance to a public road. The duration of the stays in the transfer vehicles before being loaded onto the commercial trucks ranged from 6-59 min. During this period, the median frequency of aggressive interactions per load was 18 (range: 4-65), whereas the median frequency of lying per load was 1 (range: 0-23). The duration of the stay correlated positively with the frequency of aggressive interactions (r_s = 0.89; n = 11; p < 0.001) and with the frequency of lying (r_s = 0.62; n = 11; p < 0.05). Frequency of aggressive interactions correlated positively with the temperature inside the transfer vehicle (r_s = 0.89; n = 7; p < 0.001). These preliminary results are the first to describe the behaviour of cull sows during waiting in transfer vehicles, and may suggest that this period can be challenging for sow welfare, especially for longer stays and during hot days.