Abstract

In commercial practice, the mixing of pigs from different litters is very frequently done in order to minimise the within-pen variation in weight. Aggressive behavior can be easily observed when unknown pigs are mixed into a group. Post-mixing fighting occurs between pigs that are unfamiliar with each other and some times leads to serious injury. For the establishment of social hierarchy, aggression may occur. The aim of the study was to evaluate the response of piglets fed and not with dietary plant extract (PE) when exposed to mixing-induced stress. Behavioural and physiological indicators combined with Precision Livestock Farming (PLF) methods were used. A total of 84 female piglets (Dalland), (average live weight 5.53 ± 0.1 kg, corresponding to day 0 of experimental trial) divided into 6 pens of 14 piglets each were randomly assigned to two dietary treatments: a control diet (CON) and a diet supplemented with 5 mg/kg feed of plant extract (PE). At 37 d of the experimental trial, half the animals of two treated pens (7+7) and half the animals of two control pens (7+7) were mixed. The experimental trial lasted 59 days. Blood from piglets of each treatment was collected by anterior vena cava puncture before mixing, on day 37, and after mixing, on day 39, for assessing total blood antioxidant activity, by Kit Radicaux Libres (KRL) test and haptoglobin (HPT) and cortisol concentration as biological indicators of stress. Behaviour measurements were performed using an ethological rating scale and Precision Livestock Farming methods as indicator of qualitative behavioural assessment. Dietary treatment and mixing affected total antioxidant activity (P < 0.05) of whole blood that was higher in the PE group and after mixing. A trend effect of mixing was found for cortisol and haptoglobin which were significantly (P < 0.05) lower in the PE group. The rating scale and PLF showed significant variation in the abnormal animal behaviours due to mixing; continuous monitoring of pigs by PLF showed more (P < 0.05) animal activity in the PE group than in CON. In this context, the behaviour measurements were demonstrated to be simple and reliable tools for evaluating pig behaviour and KRL test was an effective method for assessing antioxidant activity.

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