Duodenal Infusions of Palmitic, Stearic or Oleic Acids Differently Affect Mammary Gland Metabolism of Fatty Acids in Lactating Dairy Cows

Manuscript received 29 Jan 98. Initial reviews completed 10 March 98. Revision accepted 16 June 98.

Francis Enjalbert^{, *}, Marie-Claude Nicot^*, Corine Bayourthe, and Raymond Moncoulon^*,

^* École Nationale Vétérinaire, Département Élevage & Produits, Laboratoire d'Alimentation, 31076 Toulouse Cedex, France and  École Nationale Supérieure Agronomique, Laboratoire d'Ingénierie Agronomique, 31076 Toulouse Cedex, France

The effect of dietary lipids on the fatty acid (FA) profile of cows' milk fat is mainly dependent on digestive processes and mammary gland uptake and metabolism of FA. The objective of this study was to determine the separate effects of high arterial concentrations of 16:0, 18:0 and cis-18:1(n-9) on uptake, synthesis and 18:0 desaturation rate in the mammary gland of lactating dairy cows, via arterio-venous differences and mammary gland balance of FA. In a 4 × 4 Latin square, four lactating Holstein cows with cannula in the proximal duodenum were infused duodenally with a mixture providing daily 0 (C treatment) or 500 g FA with mainly 16:0 (P treatment), 18:0 (S treatment) or cis-18:1(n-9) (O treatment). Significantly higher arterial concentrations of infused FA in arterial plasma nonesterified FA and triglycerides (NETGFA) were observed with P and O treatments, but the effect of the S treatment was much lower. Arterio-venous differences of NETGFA increased with arterial concentrations. The number of synthesized FA in the mammary gland was not significantly affected by duodenal infusion of FA. Mean chain length was significantly reduced by P and O treatments, suggesting an effect of mammary gland uptake of long-chain FA on the termination process of mammary gland synthesis of FA. Across all treatments, 4:0 mammary gland balance increased linearly (r = 0.67, P = 0.004) with mammary gland FA uptake. Mammary gland desaturation of 18:0 to cis-18:1(n-9) averaged 52% and was not significantly affected by treatments, but was reduced by trans-18:1 mammary gland uptake. Uptake, synthesis and desaturation of FA by the mammary gland of dairy cows are affected by arterial concentrations of 16:0, 18:0 and cis-18:1(n-9).

The Journal of Nutrition Vol. 128 No. 9 September 1998, pp. 1525-1532
Copyright ©1998 by the American Society for Nutritional Sciences

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