Effect of lecithins partly replacing rumen-protected fat on fatty acid digestion and composition of cow milk

The effects on fatty acid digestibility and milk fat composition of calcium soaps of palm oil fatty acids and of a 25% replacement of the Ca soaps by four different lecithins (raw, deoiled and deoiled/partially hydrolysed soy lecithin, raw canola lecithin) and soybean oil were investigated in six la ctating cows each. The complete diets contained the lipid supplements at pr oportions of 30 g fatty acids/kg dry matter. Partial replacement of Ca soap s by soy or canola lecithins and soybean oil had small but significant effe cts on fatty acid digestion and utilisation, as well as the fatty acid prof ile in milk. Relative to Ca soaps alone, C16:0 digestibility was slightly h igher with lecithins, and percentage of conjugated linoleic acid and trans C18:1 in milk fat increased while proportion of C16:0 decreased. Deoiling o f lecithins slightly reduced the effects on C16:0 digestibility and excreti on with milk. The influence of lecithin processing was higher than the diff erences between raw soy and raw canola lecithin. Nevertheless, most of the few effects observed may be related to the fatty acids supplied with the le cithins but, regarding C18:1 trans-ii and odd chain fatty acids, there is s ome evidence that lecithins impair rumen microbial activity less than soybe an oil.