Effects of Supplementing Lipid-Encapsulated Echium Oil on Lactational Responses and Milk Fatty Acid Composition
Echium oil is a terrestrial source of n-3 fatty acids (FA) that is particularly high in the n-3 FA stearidonic acid (SDA; 18:4 6c,9c,12c,15c) which bypasses the rate limiting step of delta-6-desaturase in conversion to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in mammalian tissues. The objective of this study was to evaluate the impact of feeding a lipid-encapsulated echium oil (EO) supplement on animal production and milk fatty acid concentrations. Twelve Holstein dairy cattle (229 ± 62 days in milk) were assigned randomly to treatment sequence in a 3×3 Latin Square design. Treatments were a control diet (CON; no added EO), 1.5% EO (1.5% EO), or 3.0% diet dry matter (DM) added EO (3.0% EO). Treatment periods were 14 days with the final 4 days used for sample and data collection. The statistical model included the random effect of cow nested within square and the fixed effects of treatment and period. Compared with CON, EO treatments had no effect on dry matter intake (26.6 kg/day; P=0.93), milk yield (30.5 kg/day; P=0.34), or milk protein yield (1.1 kg/day; P=0.84). Increasing EO supplementation increased milk fat concentration (4.1, 4.2, 4.3%; P<0.05) and fat yield (1.24, 1.27, 1.32 kg/day; P<0.05) but decreased milk protein concentration (3.56, 3.54, 3.47%; P<0.01) for CON, 1.5% EO, and 3.0% EO, respectively. Compared with CON, the concentration of total saturated FA in milk fat decreased with increasing EO supplementation (73.7, 72.4, and 71.1 g/100 g FA, P<0.0001). Increasing EO supplementation increased milk fat concentration of total n-3 FA (0.49, 0.65, 0.81 g/100 g FA, P<0.0001), α-Linolenic acid (18:3 n-3) (0.38, 0.47, 0.58 g/100 g FA, P<0.0001), and SDA (0.02, 0.06, 0.09 g/100g FA, P<0.001) for CON, 1.5% EO, 3.0% EO, respectively. For 1.5% EO and 3.0% EO milk fat concentration of EPA was 0.05 g/100 g FA vs. 0.03 g/100 g FA for CON (P<0.0001). DHA was not detected in milk fat. Transfer of SDA from the EO supplement into milk fat was 3.4% and 3.2% for the 1.5% and 3% EO treatments, respectively. In conclusion, supplementation with a lipid-encapsulated EO did not negatively impact lactational responses and increased the concentration of n-3 FA in milk fat. The concentration of n-3 FA in milk fat however, was still a minor component of total milk FA.
n-3 Fatty Acid