Influence of season and pasture feeding on the content of α-tocopherol and β-carotene in milk from Holstein, Brown Swiss and Modicana cows in Sicily.

It has been shown that several factors such as feed source and breed might influence milk fat-soluble antioxidants (AOs). This study investigated pasture feeding effects and dairy cattle breed on the content of α-tocopherol and β-carotene in cows' milk by monitoring two grazing seasons (spring and fall) as well as a summer nopasture season. Four dairy farms located in Sicily were selected: two with both Holstein and Brown Swiss cows and two with only a Modicana (M) local breed cows. Bulk milk samples of each breed per farm were collected. Milk α-tocopherol and β-carotene were highest during spring (16.2 and 9.7 μg.g-1 of fat, respectively), lowest during fall (11.2 and 0.8 μg.g-1 of fat, respectively) and intermediate during summer (13.3 and 2.5 μg.g-1 of fat, respectively). These results indicate that grazing pasture season has an important impact on milk fat-soluble antioxidant content. In particular, higher milk AO levels in spring compared to fall might be attributed to several factors such as differences in the quality and composition of pasture, differences in pasture intake and even the climate. Breed effect on milk AO contents was not so pronounced. Milk β-carotene levels did not differ significantly among breeds. Saturation of milk β-carotene may explain similar vitamin levels among breeds in spring despite different pasture intakes. It was interesting that significant levels of α-tocopherol were detected in milk from M cows during summer. The latter effect could be masked by the considerably higher pasture intake of M in spring compared to the other two breeds.