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Play behaviour in juveniles is reduced by threats to animal welfare such as hunger and perceived danger. Conversely, engagement in play behaviour has been linked to the presence of positive-valanced affective states. Hence, play behaviour has been proposed to be an indicator of positive animal welfare. However, the interpretation of play in animals remains challenging due to its variability between and within species as well as complex motivating factors. To clarify underlying factors, we investigated, as part of the H2020 project ClearFarm, the relationship between locomotor and social play behaviour and physiological (i.e., growth and saliva cortisol), clinical (i.e., faeces score and ear damage) and behavioural (i.e., visits to feeder and drinker, tail posture and tail motion) measures in conventional Yorkshire × Landrace pigs before and after weaning. Weaning is a stressful event in the life of pigs typically involving abrupt separation from the sow, dietary change, and regrouping in a novel environment. In total, 24 litters [pigs/litter: (mean ± SD) 13 ± 2; age at weaning: 26 ± 2 days] raised under conventional husbandry conditions were included in this study. Before weaning, increased performance of locomotor play was associated with increased growth rate, absence of diarrhoea (indicated by liquid faeces), and increased frequency of visits to the drinker. During the first 48 h post-weaning, increased locomotor play was observed in pigs with increased growth, absence of diarrhoea, absence of ear damage, and increased frequency of visits to the feeder. Social play positively related with growth pre- and post-weaning. No relations between play behaviour and saliva cortisol, tail posture and tail motion were observed. Our findings corroborate the idea that an animal in a more favourable condition (e.g., well-nourished and without sickness or injuries) are motivated to perform more play behaviour. The methods, results and discussion will be presented in detail.

Modern livestock production systems can heavily challenge the welfare of animals. A way to manage farm animal welfare in real-time is through the use of Precision Livestock Farming (PLF) systems. The aim of this chapter is to present the authors’ experience in conducting research towards the development of a PLF system that can provide early warnings to pig farmers when the risk of tail damage is high. During our work, we identified challenges related to: (1) choosing the gold standard; (2) choosing the appropriate technology; (3) performing model validation and implementation. Choosing the gold standard for tail damage is challenged by the fact that tail damage will have different stages of development. Also, choosing the optimal time to raise the warning is a compromise between warning early enough to provide farmers’ with sufficient time to prevent the problem and late enough so that the probability of developing into a real problem is high. The gold standard must also be easy to standardise between different observers and conditions. Choice of appropriate technology needs to consider that tail damage is a multifactorial welfare problem with multiple risk factors and thus, several sensor technologies may be needed. Also the nature of the animals to possibly explore and destroy a sensor as well as the harsh environment of livestock buildings is a challenge. Major barriers for performing model validation and implementation are that already in the beginning, data needs to be saved for internal validation, and collaboration contracts with research herds across nations, farmers and information technology companies needs to be in place; to ensure data for external validation and prototype development. Developing a PLF system for welfare monitoring demands that several considerations and decisions are made already in the beginning. These considerations will take time and decisions made will often be a compromise.

In order to investigate the sensitivity of play behaviour to welfare threats, we recorded play before and after weaning and related play behaviour to piglet growth rate. The duration of locomotor-rotational play (PLAY) was recorded for 154 piglets (12 litters) from 07:00 to 22:00 h on days -1 and +2 relative to weaning (day 0). The pigs were weighed on days -7, 0 and +2, and their growth rates were calculated from day -7 to 0 (GB), as well as from day 0 to +2 (GA).Both GB and GA were converted to categorical variables based on their 33% and 67% quantiles (Low, Medium, High). The relation between PLAY on day -1 and GB, as well as between PLAY on day +2 and GA, were analysed using linear mixed effect models. A decrease in PLAY was seen from day -1 (77 sec/pig) to day +2 (5 sec/pig; Pg/day; 86 sec/pig) compared to the High (≥293 g/day; 113 sec/pig) growth category. After weaning, an interaction was found between GA and sex of the pig (Pthe growth and thereby the welfare of the pig, especially after weaning. It is unknown whether this relation is direct or an indirect effect of factors challenging the pigs at weaning.

We investigated whether hypothermia in newborn piglets could be reduced by applying different thermal aids. The experiment was performed on 150 newborn piglets from 24 sows. Right after birth, the piglets were moved to a wire mesh cage for the first 2 h of life where they experienced 1 of 7 different combinations of flooring (solid vs. slatted) and treatments: control, with no additional thermal aids on a solid floor (n = 26) or a slatted floor (n = 26); built-in floor heating (n = 31) or floor heating as a radiant floor plate on solid floor (FloorPlate; n = 19); radiant heater above a solid floor (RadiantC; n = 22) or a slatted floor (RadiantSlat; n = 18); and provision of straw on a solid floor (Straw; n = 8). Piglets’ rectal temperature was measured both continuously and manually every 10 min for the first 2 h after birth using a thermal sensor inserted in the rectum of the piglets. The rectal temperature curve was analyzed for differences in the slope of the drop in rectal temperature and the deflection tangent of the curve. Furthermore, differences in average rectal temperature, minimum rectal temperature, rectal temperature 2 h after birth, and time with rectal temperature below 35°C were analyzed. All statistical analyses were performed using a mixed model. All thermal aids/heat solutions resulted in a less steep drop in rectal temperature, a faster recovery, and, for the smaller piglets, also a greater average rectal temperature (except for built-in floor heating) and less time with rectal temperature below 35°C. The most efficient thermal aids to reduce hypothermia in newborn piglets were Straw and RadiantC. Furthermore, Straw, RadiantC, and FloorPlate also eliminated the effect of birth weight on some of these indicators of thermoregulatory success. Otherwise, FloorPlate and RadiantSlat showed an intermediate outcome for most measures. With no heating, piglets on a solid floor experienced more severe hypothermia than piglets on a slatted floor. In conclusion, several types of thermal aids can reduce hypothermia in newborn piglets, but some are more efficient and can partly eliminate the effect of birth weight on hypothermia. These results are especially important in countries where breeding for large litter sizes has resulted in a reduction in average birth weight of the piglets and, thus, creates a greater demand for an early, adequate thermal environment to secure piglet viability.