Influence of plant lecithin partly replacing rumen-protected fat on digestion, metabolic traits and performance of dairy cows

Nutrient digestibility, metabolic effects and performance were evaluated in lactating cows (n = 6 x 6) receiving diets containing one of four differen t lecithins (raw, deoiled and deoiled/partially hydrolysed sop lecithin, ra w canola lecithin) or soybean oil in combination with Ca soaps of palm oil fatty acids in a ratio of 1 : 3. A diet supplemented only with Ca soaps ser ved as a control. The complete diets consisted of forage and concentrate (0 .62 : 0.38) and total lipid supplementation was 30 g fatty acids/kg dietary dry matter. Lecithins had no effect on milk yield and milk composition. Ap parent digestibility of dry matter, organic matter and gross energy were hi ghest in the control diet and lowest in the soybean oil diet (p <0.1) with intermediate values for the lecithin-supplemented diets. Soybean oil partic ularly reduced fibre digestibility (significant with hemicellulose), wherea s this effect was reduced or even missing when lecithins, particularly raw canola lecithin and deoiled/hydrolysed soy lecithin, were used. The digesti bility of total fatty acids was not affected by the treatments. The effects were also not significant for blood plasma traits except for insulin which was significantly higher with raw than with deoiled/hydrolysed soy lecithi n. In conclusion, lecithins, particularly those technologically modified or of a low polyenoic fatty acid content, might be preferred to oils when use d as an energy source whereas they failed to improve digestibility of rumen -protected fats.