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

Abstract

fournissant aux graines une q-uantit6 €quivalente de graisse. Les p6riodes exp6rimentales duraient six semaines et chaque vache recevait 6 000 UI d'ac6tate de dl-a-tocoph6ryl danJes deux dernidres semaines de chaque p6riode. Le rendement ainsi que Ia composition et la saveur du lait €taient rn"ru.6, d la fin de la quatridme et de la sixidme semaine. L'administration de SCAG abaiisait (P = 0,0@1) Ia prise alimentaire (matidre sdche) mais lei r6gimes compldment6s fournissaient plus de EN' qle le regime non compl6ment6 (p = b,OSS). Le rendement en lait, en m.g. et en 6nergie 6tait augment6 par la compl6mentation lipidique soit respectivement P < 0,00L, P < 0,001 etP : 0,003. Le rendement en prot6ine 6tait abaiss6 chez les vaches recevant SCAG' Le r6gihe compl6ment6 aux graines de soja provoquait une diminution de la concentration lipidique du lait, mais seulement avant administration de vitamine EI Ce m6me iegi.. aicroissait les teneurs en cr-tocoph6rol du lait (P < 0'05). Le lait des vaches nourries aux graines de soja 6tait particulidiement sensible )r I'oxydation (P < 0,01). L'intensit6 du go0t d'oxydation 6tait-Ia m6me avant ei pendant I'administration de vitamine E. L'apport d'un compl6ment de graisse abaissait la proportion d9s-acidjs gras ir chaine courte et ir chaine moyenne (P < 0,001) et accroissait celle des acides gras en.Cl8_dans le lait (P < 0'001)' La lroportion des acides gras polyinsatur6s dans le lait 6tait augment€e par la distribution des graines de soja, mais pas par I'adjonciion de SCAG. Le sofa g.uin!. entibres peut dchapper a U UiotryOiog6nation dans le rumen, et ainsi rendre le lait sensible h

Effect of legume–grass silages and α-tocopherol supplementation on fatty acid composition and α-tocopherol, β-carotene and retinol concentrations in organically produced bovine milk

“…2 (Tables 4 and 6). Some studies have reported higher milk a-tocopherol concentration when fat has been fed (Charmley and Nicholson, 1994;Focant et al, 1998;Givens et al, 2003). One possible explanation to this is higher absorption of the vitamin in the small intestines when a-tocopherol is fed together with fat, as the a-tocopherol is absorbed through the same mechanism, passive diffusion, as absorbs lipids (McDonald et al, 2002).…”

Influence of feeding different types of roughage on the oxidative stability of milk

“…Moreover, numerous studies have shown that antioxidants as tocopherols and carotenoids can be transferred from the feed to the milk and thereby improve the oxidative stability of milk (Barrefors, Granelli, Appelqvist, & Bjoerck, 1995;Focant et al, 1998;Granelli, Barrefors, Bjoerck, & Appelqvist, 1998). Other studies have shown no effect of supplementing the diet with vitamin E (Schingoethe, Parsons, Ludens, Schaffer, & Shave, 1979;Charmley & Nicholson, 1995).…”

“…To a certain extent the composition of milk reflects the composition of the feed given to the dairy cows (Bugaud, Buchin, Coulon, Hauwuy, & Dupont, 2001;Ramaswamy et al, 2001). Consequently, certain feeding regimes can increase the content of polyunsaturated lipids and make the milk more vulnerable to oxidation (Barrefors, Granelli, Appelqvist, & Bjoerck, 1995;Charmley & Nicholson, 1995;Hermansen, 1995;Focant et al, 1998;Morales, Palmquist, & Weiss, 2000;Bugaud et al, 2001;Timmons, Weiss, Palmquist, & Harper, 2001). Moreover, numerous studies have shown that antioxidants as tocopherols and carotenoids can be transferred from the feed to the milk and thereby improve the oxidative stability of milk (Barrefors, Granelli, Appelqvist, & Bjoerck, 1995;Focant et al, 1998;Granelli, Barrefors, Bjoerck, & Appelqvist, 1998).…”

The effect of feeding soybean oil to mid-lactation dairy cows on milk production and composition and on diet digestion

“…Consequently, effects on rumen fermentation and metabolism are minimized. The influence of soybeans on production of milk and milk fat is usually positive in response to the increased energy intake (Charmley and Nicholson 1994). A proportion of the oil escapes biohydrogenation and is absorbed as unsaturated fatty acids and ultimately incorporated into milk fat (Charmley and Nicholson 1994).…”