Influence of Different Feed Physical Forms on Mandibular Gland in Growing Pigs
Department of Veterinary Medicine, University of Perugia, Via San Costanzo 4, 06126 Perugia, Italy
School of Biosciences and Veterinary Medicine, University of Camerino, Via Pontoni 5, 62032 Camerino, Italy
Institute of Animal Nutrition, University of Veterinary Medicine Hannover, Foundation, BischofsholerDamm 15, D-30173 Hannover, Germany
Department of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
Author to whom correspondence should be addressed.
These authors share senior co-authorship.
Received: 9 May 2020 / Revised: 19 May 2020 / Accepted: 21 May 2020 / Published: 24 May 2020
The study was carried out on growing pigs fed with different dietary treatments based on different grinding intensities and compactions of the same diet. Chewing acts are associated with salivary production and different extents of saliva fluidity also depend on the specific glycoconjugate content. Therefore, in order to have information about the modifications induced by different feed physical forms in the pig mandibular gland, the glycohistochemical profile and the presence of aquaporin 5, a channel protein modulating the saliva fluidity, were investigated. In addition, to have wider information about the apelinergic system function, presence and localization of both apelin and its receptor were studied. Findings suggest that the different mechanical stimuli in the mouth linked to different feed physical forms likely allow one to diverse physiological behavior of the pig mandibular gland. The intense chewing activity linked to the highest feed compaction and hardness promotes an increase in pig mandibular gland secretion. In addition, saliva becomes more fluid and richer in acid glycoconjugates in order to better lubricate the bolus and protect the mouth mucosae. The apelinergic system is likely involved in the above modifications enhancing both the fluidity and the quantity of serous saliva by the pig mandibular gland.