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Megalac – effect on saturated fatty acids in milk

Almost half the fatty acids in Megalac are unsaturated (USFA) and in rumen-protected form, enabling post-ruminal delivery of USFA for use in milk fat. Work at the University of Reading in the UK (Table 1) demonstrated that cows offered Megalac had 4.4% lower saturated fatty acids (SFA) in milk fat (relative reduction 5.8%) compared to cows offered the control diet. The reduction in SFA was balanced by a significant increase in the concentration of cis-MUFA, primarily cis-C18:1, the major USFA in Megalac.

These data also highlight the effect on milk fatty acid profile of supplementing with a highly saturated fat-supplement (approximately 85% C16:0 fatty acids). Supplementing with the 'high-C16' fat source increased concentration of C16 in milk, but did not increase the concentration of total SFA in milk due to a reduction in de novo-synthesized SFA.

Table 1      Fatty acid profile of milk from cows offered a 'high-C16' or Megalac supplement 

Fatty acid ‡ (% total fatty acids) Treatment Sig.#
Control 'High-C16' Megalac
C4:0 - C10:0 9.3a  7.7b 7.9b **
C12:0 - C14:0 17.5a 13.6b 14.2b **
C16:0 38.1b 43.5a 37.4b **
C18:1 cis-9 17.9b 19.3b 21.6a **
Total SFA 75.3a 73.a 70.9b **
Total cis-MUFA 21.4b 23.1b 25.2a **

#** P<0.01   ‡ SFA, saturated fatty acids; MUFA, monounsaturated fatty acids

Means within rows with different superscripts are significantly different (P<0.05)

Aikman et al., 2012. Effect of supplementing dairy cow diets with different forms of palm oil-based supplements on the fatty acid profile of milk fat. American Dairy Science Association, Annual Conference, abstract 298.


In a further study at the University of Reading (Kliem et al., 2012), addition of Megalac to dairy diets reduced the concentration of SFA in milk by a significant 3.5% (relative reduction of 5%), with a corresponding increase in concentration of C18:1 USFA, although this was not statistically significant (Table 2). These data also demonstrate that supplementing with a Ca salt of high-C16 (78% C16) fatty acids had no significant effect on milk SFA concentration, as the additional SFA provided by the supplement was balanced by a reduction in the proportion of de novo-synthesised SFA from the mammary gland. 

Table 2     Effect of Megalac and high-C16 fat supplents on milk fatty acid profile

Fatty acid ‡ (% total fatty acids) Treatment Sig.#
Control 'High-C16' Megalac
C4:0 - C10:0 12.1 11.0 11.6 NS
C12:0 4.5 4.0 3.6 NS
C14:0 12.1 11.1 10.6 NS
C16:0 30.9 32.7 30.5 NS
C18:1 cis-9 13.7 14.8 16.2 NS
Total SFA 70.4ª 69.5ª 66.9b *
Total MUFA 17.5 18.5 19.8 NS
Total PUFA 2.6 2.6 2.7 NS

#NS - Not significant, *P<0.05

‡SFA - Saturated Fatty Acids, MUFA - Mono unsaturated acids, PUFA - Poly unsaturated fatty acids

Means with rows with different superscripts are significantly different (P<0.05)

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