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

Abstract

Effect of a-tocopherol supplementation to dairy cows on milk and plasma cv-tocopherol concentritions and bn spontaneous oxidized flavor in milk. Can

Influence of dietary fat source on oxidative stability and fatty acid composition of milk from cows receiving a low or high level of dietary vitamin E

“…The poor transfer of supplementary dietary vitamin E to milk may have been a consequence of the short (2 wk) vitamin E supplementation period. St-Laurent et al (1990) found 2 wk of vitamin E supplementation to be sufficient time to allow milk a-tocopherol levels to stabilize, and Goering et al (1976) observed a large response in milk crtocopherol concentration after only 5 d of vitamin E supplementation in the presence of a protected unsaturated fat source. However, in a study we completed more recently (Charnrley et al 1993) it was found that plasma a-tocopherol concentration in lactating cows continued to rise over an S-wk supplementation period.…”

Total antioxidant capacity: A tool for evaluating the nutritional status of dairy heifers and cows

“…Low TAC values would suggest either a deficiency in nutrients, especially antioxidants, and/or an environmental stress and disease challenge that have overwhelmed the cow's readily mobilized antioxidants (Miller et al 1993a). Supplementation with antioxidants to support the cow's self-defense systems against the toxic effects of oxygen free radicals may increase disease resistance and help counteract immunosuppression (Miller et al 1998) and off-flavors in milk (St-Laurent et al 1990;Charmley et al 1993). Oxidative stress contributes to health problems such as mastitis (Smith et al 1984;Weiss et al 1990), retained placenta and udder edema in dairy cows (Miller et al 1993a), as well as suboptimal reproduction (Miller et al 1998).…”

“…In Nova Scotia, animals received the TMR during the winter and had access to grazing during the summer, late spring and early fall in addition to receiving restricted amounts of supplements, which contained antioxidants. Since the quantity and quality of forage were higher in the summer than in the fall or spring, the pasture may have provided a substantial amount of antioxidants, especially β-carotene and vitamin E. St-Laurent et al (1990) showed that plasma α-tocopherol levels increased in cows when they consumed pasture. Similarly, since animals sole- For personal use only.…”

The difference in transfer of all-rac-α-tocopherol stereo-isomers to milk from cows and the effect on its oxidative stability

“…Feeding the cows a high level of all-rac-a-tocopheryl acetate has been the basis for control of spontaneous oxidation in milk. Several studies indicated that such an increased intake of vitamin E supplements by cows increases the a-tocopherol content of milk (Atwal, Hidiroglou, Kramer, & Binns, 1990;Charmley & Nicholson, 1994;Charmley, Nicholson, & Zee, 1993;Goering et al, 1976;Nicholson & St-Laurent, 1991;St-Laurent et al, 1990). Atwal et al (1990) supplemented the diet with 8000 to 10 000 IU of all-rac-atocopheryl acetate per cow per day and found an increase in milk tocopherol of between 17 and 34 mg per g milk fat.…”

“…Several studies of spontaneous oxidized flavour in milk have shown that a low level of a-tocopherol in the feed is critical for the oxidative stability of the raw milk (Charmley, Nicholson, & Butler, 1991;Krukovsky, Whiting, & Loosli, 1950;Schingoethe, Parsons, Ludens, Tucker, & Shave, 1978;Schingoethe et al, 1979;St-Laurent, Hidiroglou, Snoddon, & Nicholson, 1990).…”