Relazione fra apporto alimentare e livelli plasmatici di vitamina E nella bovina da latte

Relation between feed supply and plasmatic levels of vitamin E in dairy cattle. – With the aim to evaluate the relation between feed supply and plasmatic levels of vitamin E, eight dairy farms have been studied. Blood samples were collected from cows in different stages of their productive-reproductive cycle receiving variable amounts of dietary vitamin E and different levels of vitamin E have been observed in plasma. Vitamin E supplies ranged from 500 to 5000 mg/d, and they were not differentiated during the productive cycle. Plasma level of α-tocopherol was positively related to dietary intake (P<0,05). Linear regression describing the relationship between these parameters changed with cycle period. This study revealed a positive and significant relation between dietary intake of vitamin E and its plasmatic levels; this linear relationship quantitatively changes following the different phases of the productive and reproductive cycle of cows, and can be used to estimate dietary requirements of vitamin E for all categories of dairy cows. Keywords: α-tocopherol, nutrition, plasmatic levels