Livelli di pascolo, componenti volatili, antiossidanti e qualità del latte

Abstract

The aim of this study was to evaluate the effect of pasture feeding and cow s breed on milk volatiles fingerprint and to examine the effects of pasture feeding and dairy cattle breed on fat-soluble antioxidant, vitamin content in milk. Four Sicilian dairy farms were selected, two with both Holsteins and Brown Swiss cows and two with only local breed Modicana cows. Bulk milk of each breed per farm was sampled four times per experimental period (spring, summer, and autumn). Samplings within period occurred with weekly intervals. Pasture was available in spring and autumn but not in summer. Spring and autumn differed by botanical composition and plant maturity. During summer cows were grazing stubble. Additional hay and concentrate was supplemented during all periods. Milk samples were analyzed by SMart Nose®: data were statistically evaluated by Principal Component Analysis. Volatiles profiles of samples from spring and autumn compared to summer were discriminated, but not between spring and autumn. There was less variation in volatiles during autumn compared to spring. Milk volatile profiles collected at the last sampling day (spring), except for volatiles composition from Modicana milk, were similar to all samples from summer. At this day, plants were mature and almost dry and chemical composition might have been similar to stubble composition. In all periods, also when pasture was not available during summer, volatiles composition of Modicana milk was different from Holsteins and Brown Swiss milk. Differences during spring and autumn might be explained, at least in part, by the higher average pasture intake of Modicana relative to the Brown Swiss and Holsteins. Pasture benefits relative to vitamin content milk content might be obtained only after a minimum necessary exposure period of cows to pasture. Milks from Modicana had the same levels of beta-carotene of Brown Swiss compared to Holsteins cows, whereas significant higher levels of alfa-tocopherol of Modicana relative to Brown Swiss and Holsteins. As a difference to Holsteins and Brown Swiss cows who had similar feeding regimen, Modicana cows had significant higher pasture intake. Differences in vitamin content contents in milk from Modicana relative to Brown Swiss and Holsteins cows cannot be exclusively explained by breed effects but may mainly be attributed to different levels of pasture intakes.