Diet-induced milk fat depression is associated with alterations in ruminal biohydrogenation pathways and formation of novel fatty acid intermediates in lactating cows

Abstract

The biohydrogenation theory of milk fat depression (MFD) attributes decreases in milk fat in cows to the formation of specific fatty acids (FA) in the rumen. Trans-10, cis-12-CLA is the only biohydrogenation intermediate known to inhibit milk fat synthesis, but it is uncertain if increased ruminal synthesis is the sole explanation of MFD. Four lactating cows were used in a 4×4 Latin square with a 2×2 factorial arrangement of treatments and 35-d experimental periods to evaluate the effect of diets formulated to cause differences in ruminal lipid metabolism and milk fat synthesis on the flow of FA and dimethyl acetal at the omasum. Treatments comprised total mixed rations based on grass silage with a forage:concentrate ratio of 35:65 or 65:35 containing 0 or 50 g/kg sunflower oil (SO). Supplementing the high-concentrate diet with SO lowered milk fat synthesis from -20·2 to -31·9 % relative to other treatments. Decreases in milk fat were accompanied by alterations in ruminal biohydrogenation favouring the trans-10 pathway and an increase in the formation of specific intermediates including trans-4 to trans-10-18 : 1, trans-8, trans-10-CLA, trans-9, cis-11-CLA and trans-10, cis-15-18 : 2. Flow of trans-10, cis-12-CLA at the omasum was greater on high- than low-concentrate diets but unaffected by SO. In conclusion, ruminal trans-10, cis-12-CLA formation was not increased on a diet causing MFD suggesting that other biohydrogenation intermediates or additional mechanisms contribute to the regulation of fat synthesis in the bovine mammary gland.

Taxon abundance, diversity, co-occurrence and network analysis of the ruminal microbiota in response to dietary changes in dairy cows

“…Details on the experimental design have been reported by [19]. In summary, four multiparous Nordic Red dairy cows fitted with rumen cannulae in mid lactation were used in a 4 × 4 Latin Square experiment with a 2 × 2 factorial arrangement of treatments and four 35 day experimental periods.…”

“…The forage was restrictively fermented grass silage prepared from mixed timothy meadow fescue swards treated with a formic acid based ensiling additive. Concentrates comprised variable amounts of ground wheat, rolled barley, rapeseed expeller, urea and mineral and vitamin pre-mix [19]. Experimental diets were fed for 26 days followed by 9 days on L diet to minimize treatment carry-over effects.…”

The Dietary Addition of Fish Oil or Sunflower Oil Plus Starch Differently Modulates the Lipid Classes in Plasma of Lactating Cows and Goats

“…The absence of this CLA isomer in blood plasma of cows, despite a presence in milk was previously observed, but there is no obvious explanation for this and a systematic analysis of all plasma lipid fractions may help to clarify this point. Otherwise, probably that other RBH intermediates or additional mechanisms are involved in the mammary inhibition of lipogenesis, as recently suggested by a study showing the absence of trans 10, cis 12‐CLA ruminal up‐regulation in cows with MFD when fed high‐concentrate diet containing sunflower oil …”

“…Otherwise, probably that other RBH intermediates or additional mechanisms are involved in the mammary inhibition of lipogenesis, as recently suggested by a study showing the absence of trans10, cis12-CLA ruminal up-regulation in cows with MFD when fed high-concentrate diet containing sunflower oil. [35]…”

Flaxseed Oil or n‐7 Fatty Acid‐Enhanced Fish Oil Supplementation Alters Fatty Acid Composition, Plasma Insulin and Serum Ceramide Concentrations, and Gene Expression in Lambs

“…Supplementation with POA oil enhanced serum and tissue concentrations of palmitoleic acid and cis‐11 vaccenic acid, a known elongation product of palmitoleic acid (Burns, Kadegowda, et al, ). cis‐11 vaccenic acid can also be formed during ruminal biohydrogenation of linoleic and linolenic acids (Ventto et al, ). In this study, the correlation between cis‐11 vaccenic acid and palmitoleic acid concentrations was high ( r = 0.92, p < 0.0001), indicating that most cis‐11 vaccenic acid was due to elongation and not biohydrogenation.…”