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

Abstract

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 x 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).

Effect of replacing calcium salts of palm oil distillate with incremental amounts of conventional or high oleic acid milled rapeseed on milk fatty acid composition in cows fed maize silage-based diets

“…This can be explained by an increased intake of cis-9 18:1, and also due to increased mammary availability of 18:0, which is desaturated at the mammary gland level. Around 50% of 18:0 taken up by the mammary gland is desaturated (Enjalbert et al, 1998), and all studies examining responses to supplemental rapeseeds or rapeseed oil in the diet report an increase in milk cis-9 18:1 concentration (Givens and Shingfield, 2006;Glasser et al, 2008). Increases in milk fat cis-9 18:1 concentrations to both rapeseeds were linear across the range of supplements fed in this experiment, indicating the potential to further enhance milk cis-9 18:1 content.…”

Effect of replacing grass silage with maize silage in the diet on bovine milk fatty acid composition

“…This would lead to a lower rumen outflow of 18:0 and reduced mammary desaturation to cis-9 18:1 (as described by Kinsella, 1972). Enjalbert et al (1998) found that there was a negative relationship between arterial circulation of trans-18:1 isomers and 18:0 desaturation in the mammary gland. However, when taking into account desaturation ratios (by dividing cis-9 10:1 by 10:0 and cis-9 14:1 by 14:0), there was no difference in desaturation activity for each of the diets, possibly due to low variations of circulating trans-18:1 isomers in the blood between diets.…”

Ruminant milk fat plasticity: nutritional control of saturated, polyunsaturated, trans and conjugated fatty acids

“…NEFA uptake is directly related to their plasma concentration, which is itself mainly related to body fat mobilisation [29]. The ability of mammary tissue to utilise triglyceride FA from plasma lipoproteins is determined by the activity of the enzyme lipoprotein lipase than 50% of the oleic acid that is secreted into milk fat [16,57]. Furthermore, vaccenic acid (trans-11 C18:1) formed in the rumen and absorbed from the intestine can be desaturated to form rumenic acid, i.e.…”