Chicory and red clover silage to growing/finishing pigs and its influence on pigs' behaviour

Abstract: Even though roughage is a part of the natural diet for pigs, the majority of today’s pigs do not have access to it. The time the pigs in modern production system spend on eating is very short, it could be as little as 15 minutes per day. This could lead to digestive or behavioural problems. There is an unused potential for different ley crops and especially legumes, to contribute to the pigs’ nutritional supply with both protein and energy and also increase their welfare by stimulate foraging and exploratory behaviour. In this study conventional growing/finishing pigs were given free access to silage of 100% red clover or 100% chicory in excess of 80% of a recommended cereal-based feed ration. The experiment started when the pigs had a live weight of 80 kg and ended at slaughter. The pigs were video recorded with cameras throughout the experiment and their behaviour were analysed two consecutive days at two observation occasions. The pigs’ activity, body position and location in the pen were analysed. Social interactions, biting pen fittings and eating silage were observed continuously for five minutes three times per day during the observation occasions. The results showed that pigs in the control treatment were lying down more of the time and spent less time nosing on the pen floor than the pigs in the two silage treatments. This implies that pigs with access to silage were more active than the control pigs. Pigs in the control treatment had significant higher number of biting in pen fittings. The most common social interaction in all three treatments was nosing on other pig. There was significant less bitings/nibblings in the red clover treatment but more head knocks in the chicory treatment compared to the other treatments. The time spent on eating/rooting silage did not differ between the two silage treatments. Access to silage seems to have offered a higher opportunity to perform foraging behaviour and without access to silage the pigs seem to have redirect some of the exploratory behaviour towards pen fittings instead. Social behaviour was also analysed in relation to gender and the two different genotypes the pigs had (Yorkshire x Duroc or Yorkshire x Hampshire). For genotype no significant differences were seen but female pigs had a higher number of social interactions in total and higher frequency of nosings compared to the castrated male pigs. The conclusion of study is that even in this already enriched pig production system (all pigs had straw) the animal welfare can be improved with access to silage, by given a more meaningful occupation than pen manipulation. Both chicory and red clover silage did contribute to the pigs’ energy and protein supply, but red clover gave a better daily gain than chicory. Red clover also had a higher potential as roughage to improve the growing/finishing pigs’ welfare.