Impact of different controlled temperature and humidity conditions Eon the valuation of behaviour, posture and spatial needs in fattening rabbits(space and height) under different temperature and humidity conditions in fattening rabbits

Alexandra Contreras-Jodar^1,2*Antoni Dalmau²Marc Bagaria²Marilys Rendon²Ahmed A. K. Salama³Antonio Velarde²

• ¹Department of Agri-Food Engineering and Biotechnology (DEAB), Universitat Politecnica de Catalunya Escola d'Enginyeria Agroalimentaria i de Biosistemes de Barcelona, Castelldefels, Spain
• ²Animal Welfare, Institut de Recerca i Tecnologia Agroalimentaries Centre de Monells, Monells, Spain
• ³Department of Animal and Food Sciences, Universitat Autonoma de Barcelona Facultat de Veterinaria, Bellaterra, Spain

This study aimed to evaluate the effect of thermal conditions on the posture and behaviour of fattening rabbits and to determine the minimum space allowance and height required in a transport container to allow for thermoregulatory behaviours. Thirty-six rabbits (2.27±0.13 kg) of hybrid genetics were fasted for 6 h and then exposed to three thermal treatments (T1: 15.3ºC and 63.0% RH; T2: 22.9ºC and 38.3% RH; T3: 31.1ºC and 35.5% RH) for 8 h in a climate-controlled chamber. Postural and behavioural responses were continuously recorded via video and subsequently analysed using standardized ethograms. These responses were also analyzed by comparing the first and last 4 h of exposure to assess temporal changes in response to thermal treatments but no significant differences were found between them. The space occupied by each rabbit was quantified through digital image analysis. Results showed that the warmer the thermal treatment, the more frequently the rabbits adopted sprawled postures, while self-grooming and exploratory behaviours decreased and inactivity increased significantly. Rabbits tend to avoid physical contact under higher temperatures, likely as a mechanism to enhance heat dissipation.The space occupied varied with posture: 168 cm 2 /kg when lying, 205 cm 2 /kg in sternal sprawl, and 277 cm 2 /kg in lateral sprawl, corresponding to a stocking density of 60, 49, and 36 kg/m 2 , respectively. Height needed to perform the different behaviours ranged from 13cm in sprawled positions to 32cm when upright. During the 8h treatment, rabbits spent approximately 1% of the time in upright posture, suggesting limited use of vertical space. In T1, rabbits require a minimum of 168 cm 2 /kg (60 kg/m 2 ) to lie down all at the same time. In T2 and T3, rabbits require 205-277 cm2/kg (36-49 kg/m 2 ) to allow sprawling in static, non-ventilated conditions. A cage height of ≥ 35cm is necessary for rabbits of this weight to stand upright. These findings highlight the importance of adjusting space allowance and height in transport containers based on thermal conditions to safeguard rabbit welfare during transport. These experimental results need validation under commercial transport conditions.