THE EFFECTS OF PASTURE DRYNESS ON SHEEP MAMMARY GLAND AND FARM INCOME

Question Sheep is the most bred species in the Central Italy Apennine. Using natural pastures as trophic resources and grazing activity is fundamental to maintaining the grassland biodiversity. The increase in summer aridity causes a decrease in grasslands pastoral value: it is registering an anticipation of the moment of pasture maximum flowering and a shortening of the period between maximum flowering and maximum dryness of pastures. The increase in drought stress negatively effects forage quality and quantity and it is therefore detrimental to the sustainability of extensive sheep farms because it affects the morpho-functional features of the animals and greatly reduces milk production.The loss of farming sustainability shall lead tothe disappearance of a pivotal cultural and natural heritage. This work aimed to find strategies buffering the effects of increasing summer drought stress ensuring an economical sustainability to the farmers. In this study we evaluated the effect of food supplementation on the apelin (APLN)/apelin receptor (APLNR) system in ovine mammary gland and on milk/cheese production. Methods A flock of adult ewes was free to graze from June until pasture maximum flowering (MxF). Then until pasture maximum dryness, the flock was divided in two groups: control (Cnt), fed only on pasture, and experimental (Exp), also supplemented with 600 g/day/head of cereals. APLN and APLNR were assessed by Real-Time PCR and immunohistochemistry on the mammary glands of subjects pertaining to three groups. Quality and peculiar features of cheese were evaluated by means of sensory panel. Cheese consumer preference and willingness-to-pay were evaluated and analysis of the cost-benefit analysis was applied to assess the economic impact of feed supplementation. Results APLN and APLNR were detected in alveolar and ductal epithelial cells. APLNR expression showed significant difference during pasture vegetative cycle. Also, milk production and composition showed significant difference among the three animal groups. Economical analysis showed a positive effect of food supplementation. Conclusions The reduced APLNR expression during parenchyma involution enables us to hypothesize its modulating role in the system control. Food supplementation can play a fundamental role because is able to preserve the economic sustainability of farm, thus avoid in gland abandonment.