Inclusion of silage in diets to fattening pigs: effect on gastric ulcers and skin lesions

Abstract

Limited access to high-quality feed protein for pigs has made it necessary to evaluate new protein sources that both promote sustainable pig production and meet the nutritional requirements of pigs. Providing pigs with roughage has positive effects on their behaviour and gut health. However, roughage is seldom given as a part of the pigs’ diet and often has a long straw length. Knowledge is lacking on the effect of feeding silage with smaller particle size and as a part of the pigs' diet on pig behaviour and welfare. This study evaluated the influence of feeding fattening pigs silage with different particle sizes on aggressive encounters, measured as the number of skin lesions, and on the occurrence of gastric lesions and ulcers. In total, 128 Swedish Yorkshire × Hampshire pigs were fed either a commercial control feed without silage (Pellet-C), or silage mixed with commercial feed, either in a pellet (Pellet-S) or in a total mixed ration (TMR) with chopped (TMR-Ch) or intensively treated silage (TMR-Ex). Skin lesions were assessed twice in the study according to the Welfare Quality® protocol. The first assessment was performed when the pigs were 105 days old and the second assessment at 132 days of age. Gastric lesions were examined in both the pars oesophagea and the pars glandularis region of the stomach. Stomachs were collected after slaughter, and gastric lesions were scored based on established scoring criteria. There was a treatment × assessment interaction on the number of skin lesions on the ear (P = 0.049). Apart from this interaction, no other effect of treatment on the number of skin lesions could be observed between the treatments or the assessment occasions. Treatment had a clear effect on the occurrence of gastric lesions and pigs fed the fresh silage (TMR-Ch and TMR-Ex) had a lower occurrence of gastric lesions and ulcers compared to the pelleted treatments (Pellet-C and Pellet-S) (P = 0.001). This study could not show any clear reduction effect of dietary silage inclusion on skin lesions. However, feeding silage in TMR significantly reduced the occurrence of stomach ulcers.