IMPROVED REPRODUCTIVE EFFICIENCY OF DAIRY COWS SUPPLEMENTED WITH OMEGA-3 FATTY ACIDS (PART I)

Omega-3 (n3) fatty acid (FA) supplementation in dairy cows has several beneficial effects on reproductive performance. These FAs can affect oocyte maturation directly, by altering the lipid composition of the oocyte membrane. However, they can also do so indirectly by influencing the concentration of prostaglandins (PG) in the surrounding fluid. Zeron et al. (2002) have reported that the number and quality of sheep oocytes have increased after supplementation with n3 FA. An increase in embryo survival and a reduction in PGF2α levels have also been reported in cows supplemented with n3 FA.

This improvement is due to the reduction in the relationship between n6 and n3 FA. These two types of FA are precursors of different series of eicosanoids (among which are prostaglandins), despite using common enzyme complexes such as elongase and desaturase. Linoleic acid (n6) is a precursor to prostaglandin F2α (PGF2α, series 2). While Alpha-linolenic acid (n3) is a precursor of prostaglandin F3α (PGF3α, series 3). Serie 3 of PG is less inflammatory than series 2 of PG. The fact that both types of FA (n6 and n3) use the same enzyme complex for their metabolism, makes them compete for it. Therefore, the increase of n3 FA in the ratio causes a lower amount of PGF2α. Another important effect of supplementation with n3 FA is the improvement in the composition of the FA of cell membranes, which increases their fluidity when they have a higher content of n3 FA.

Effect of HI-FLAX® (protected n3 FA) on the oocyte quality of dairy cows

In order to evaluate the effects of supplementation with different sources of n3 FA on oocyte quality in dairy cows, 63 Holstein cows were divided into 3 groups for 84 days. The treatments consisted of the supplementation of 500 g/d of hydrogenated fat in the control cows (CTR), 350 g/d of extruded flaxseed + 390 g/d of hydrogenated fat (EXT), and 500 g/d of HI-FLAX ® (HFL). Both HFL and EXT provided the same amount of C18: 3 (n3). At the end of 84 days, a collection of oocytes was done. Oocytes were counted and a quality evaluation (Q1 – Q4) was carried out according to their morphological characteristics.

Cows that consumed HI-FLAX® tended (P = 0.15) to present a higher number of viable oocytes (10.5), compared to control cows and those that consumed extruded flaxseed (8.5 and 8.6 respectively). Regarding the quality of the oocytes, HFX cows tended (P = 0.11) to present more quality 1 and 2 oocytes (Q1+Q2, 4.8), compared to EXT and CTR cows, which showed 3.8 and 3.4 oocytes, respectively. However, the difference among treatments was statistically significant (P = 0.05) when we analyzed quality 2 oocytes (Q2), HFX cows showed 2.7 oocytes, 1.9 in the EXT, and 1.0 in CTR ones. These results agree with Zeron et al. (2002), who observed the improvement of the quality of oocytes in sheep that were supplemented with n3 FA.

With this trial, it was concluded that the supplementation of dairy cows with HI-FLAX® increase both, quantity and quality of the oocytes in dairy cows.