Effects of alimentary supplementation on mammary gland activity in sheep grazing on semi-natural pasture

Introduction: Grazing is a main tool for the safeguard of pasture biodiversity and the maintenance of pasture nutritional value. The increasing summer aridity trend results in the availability of a pasture with a less protein content and a high fiber content with, in addition, an increasing lignin percentage. This scenario is forecasting of farm productive loss generating the pasture abandonment risk. We attempted to search an easy and less expensive solution to improve the farm income and preserve the pasture biodiversity. Materials and Methods: A flock of 45 adult female sheep were conducted on a semi-mesophylous pasture in June, they were free to grazing until the moment of pasture maximum flowering (MxF); while until the maximum pasture dryness the animals were divided in two groups: the control group (Cnt) fed only on the pasture, while the experimental group (Exp) was also supplemented with 600 g/day/animal of corn and barley (1:1). We assessed immunohistologically and by realtime-PCR the expression of apelin (APLN) and its receptor (APNLR) in the mammary gland of sheep at the beginning and at the end of the period of differentiated diets and monitored milk production and composition of lactating animals during the trial. Results: Different immunopositivity to APLN and APLNR and significant differences in APLNR expression evidenced by realtime-PCR were observed in mammary gland between pasture maximum flowering and dryness (Cnt-Exp) samples. None difference was observed between Cnt and Exp samples. Milk production and composition showed significant differences among MxF, Cnt and Exp samples. Conclusion: APLN and APLNR expression in sheep mammary gland were not influenced by alimentary supplementation, that positively affected milk production and composition in Exp group respect to the Cnt one. Findings gave useful indication on APLN/APNLR action on sheep mammary gland; indication for flock management allowing to farm income improvement also emerged.