EFFECT OF α-TOCOPHEROL SUPPLEMENTATION TO DAIRY COWS ON MILK AND PLASMA α-TOCOPHEROL CONCENTRATIONS AND ON SPONTANEOUS OXIDIZED FLAVOR IN MILK

Abstract

An α-tocopherol supplementation study was conducted with 12 Holstein cows, assigned to one of three dietary α-tocopherol levels, 0, 700, and 3000 IU cow−1 d−1, as dl-α-tocopheryl acetate. Cows were fed a basal diet of alfalfa silage and a barley-corn-soybean meal grain mix. The study consisted of a pretreatment (wk 0), a treatment (wk 1 to 5) and a posttreatment phase (wk 6 and 7). Peak milk α-tocopherol levels were observed at wk 1 for the 700 IU group and at wk 2 (P < 0.05) for the 3000 IU group. During wk 2 to 5 milk α-tocopherol concentrations were highest for the 3000 IU group and peaked at 22.0 μg g−1 lipid; plasma α-tocopherol levels increased by 0.7 and 1.3 μg mL−1 for the 700 and 3000 IU groups. By the end of the posttreatment phase, milk α-tocopherol concentrations had returned to wk 0 levels. A field study was conducted of four herds (142 cows) with a chronic spontaneous oxidized flavor (SOF) milk problem. The herds were fed α-tocopherol at 0, 700 and 3000 IU cow−1 d−1 in a changeover design of 2-wk periods followed by access to spring pasture for 4-wk. Milk flavor improved when higher levels of α-tocopherol were fed and SOF was minimal when pasture was grazed. The percentage of cows in the herds producing SOF milk was 68, 61, 56, and 8 for the 0, 700 and 3000 IU d−1 treatments and pasture, respectively. α-Tocopherol levels were highest (P < 0.05) in milk for the 700 IU d−1 level of feeding and in plasma (P < 0.05) when pasture was consumed. Milk and plasma α-tocopherol levels did not correlate well with improved flavor scores. Key words: Spontaneous oxidation, milk, α-tocopherol, dairy cow, flavor, vitamin E