Short communication: The effects of supplementation of various n-3 fatty acids to late-pregnant dairy cows on plasma fatty acid composition of the newborn calves

Abstract

The passage of long-chain fatty acids (FA) through the placenta in ruminants is limited. However, essential long-chain polyunsaturated FA, and especially n-3 FA, are crucial for normal development of the bovine fetus; therefore, uptake of these FA by the embryo must occur during pregnancy. The objectives of the present study were to examine the effects of enrichment of dam plasma with various n-3 FA during late gestation on newborn calf plasma FA composition. Twenty-seven multiparous cows at 256d of pregnancy were divided into 3 groups and fed encapsulated fats as follows: 1) control: supplemented at 240g/d per cow with saturated FA; 2) flaxseed oil (FLX): supplemented at 300g/d per cow with fat that provided 56.1g/d per cow of α-linolenic acid (ALA) from flaxseed oil; and 3) fish oil (FO): supplemented at 300g/d per cow with fat that provided 5.8 and 4.3g/d per cow eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil, respectively. Blood samples were taken from dams twice weekly and from calves immediately after calving before first colostrum. The FA composition in plasma was determined in dams at the last sample before parturition, on average 2d before calving. Feeding cows with FLX resulted in a 2.6-fold increase in the proportion of ALA in dam plasma as compared with the control. The proportion of EPA in cow plasma was not different between groups; however, the percentage of docosapentaenoic acid (DPA) was 1.4 and 2 times higher, respectively, in cows fed FLX and FO than in the controls. In addition, the plasma proportion of DHA was 15 times higher in FO cows than in controls. In calves, no differences between groups were observed in the plasma proportions of ALA and EPA; however, the proportion of DHA was 1.9 times higher in the FO calves than in controls. Across treatments, data showed no correlation between the proportions of ALA, EPA, and DPA in dam and calf plasma; however, positive correlation was demonstrated between dams and calves in DHA proportion (r=0.55). In conclusion, the distinct plasma FA profile in newborn calves compared with dams was apparently due to low permeability of the bovine placenta to polyunsaturated FA. Enriching late-gestation dairy cows with n-3 FA increased the proportion of DHA, but not ALA, in newborn calf plasma, probably because of the essentiality of DHA to fetal development.