The effects of extruded flaxseed supplementation to high-yielding dairy cows on milk production and milk fatty acid composition

The objectives of this study were to determine the effects of extruded flaxseed supplementation to high-yielding dairy cows on milk yield and fatty acid profile. One-hundred Israeli-Holstein dairy cows averaging 150 days in milk (DIM) were stratified into two treatment groups on the basis of milk production, DIM and parity. The treatments were: (I) control-cows were fed a lactating-cows diet; and (2) extruded flaxseed (EF)-cows were fed a lactating-cows diet which included an extruded supplement at 40g/kg dry matter (DM) that contained flaxseed and wheat bran at 700 and 300g/kg, respectively. The average daily milk yield was 2.7% higher in the EF group than in the control group (45.4 and 44.2 kg/d, respectively; P<0.0001), the fat content was lower in the EF group (34.1 and 36.3 g/kg, respectively; P<0.03), and fat yield was unaffected. The a-linolenic acid (ALA; C18:3 n-3) in milk fat was 3.1 times. eicosapentaenoic acid (EPA; C20:5 n-3) 2.4 times, and docosapentaenoic acid (DPA; C22:5 n-3) twice as high in the EF group as in the control group (P<0.0001). The overall n-3 fatty acids (FA) concentration and yields were 2.8 times as great in the EF group as in the control group (10.9 and 3.9 g/kg and 16.7 and 6.0 g/d, respectively: P<0.0001). The saturated FA (SFA) content in milk fat was 36g/kg lower in the EF group than in the control (622 and 658g/kg of FA: P<0.0001). On the average, the EF increased the proportion of mono-unsaturated FA (MUFA) by 10% and polyunsaturated FA (PUFA) by 11.8% compared with the control. The n-6:n-3 FA ratio was decreased by the EF Supplementation from 11.9 in the control group to 4.2 in the EF group (P<0.0001). In conclusion, feeding an extruded supplement containing 700g/kg of EF, at a DM rate of 40g/kg. increased the milk yield and decreased the fat percentage. The n-3 FA concentration and yield in milk fat were 2.8 times as high and the n-6:n-3 ratio was 2.8 times lower in the EF group than in the controls. The SFA proportion decreased and the MUFA and PUFA proportions increased in response to EF supplementation. (C) 2009 Elsevier B.V. All rights reserved.