Preliminary Investigation on Salivary Enzymes of Massese Sheep

Saliva is an important biological matrix that allows the investigation of various welfare parameters; in ruminants, it is abundant and can be easily collected without requiring professional veterinary intervention. The aim of the investigation was to provide additional information on both digestive and antioxidant enzymes of sheep farmed in good welfare conditions, assessed with the Animal welfare indicators (AWIN) protocol. Small surgical forceps holding a Salivette^® device (Sarstedt, Nümbrecht, Germany) were gently inserted into the sheep's mouths without any force. The sheep chewed the swabs independently for a few seconds, allowing saliva collection. Seventeen enzymes from the saliva of 15 sheep were analyzed: antioxidant enzymes (catalase, glutathione S transferase), proteolytic enzymes (trypsin, chymotrypsin, N-aminopeptidases, carboxypeptidase A and B), carbohydrases (glucose oxidase, amylase, cellulase, lignin peroxidase, chitinase and α-glycosidase), and esterases (alkaline and acidic phosphatases, lipase and esterase). Esterase activity showed the highest value (12.95 ± 1.25 U/mg of proteins), whereas lignin peroxidase activity showed the lowest (2.23 ± 0.37 µU/mg of proteins). The activity of all enzymes was observed except for glutathione S transferase and α-glycosidase. Among the enzymes, lipase activity has already been identified as a biomarker of stress in sheep saliva. This investigation may represent a basis for further investigations into the diet and adaptive responses of sheep to different environmental conditions. Furthermore, samples collected using the Salivette^® device can be easily obtained without requiring specialized staff and without causing any stress to the animals. Further investigations into the origin of individual enzymes using a proteomic approach are desirable.