Feeding peripartal dairy goats with saturated or unsaturated lipid supplements : effects on plasma, colostrum and milk fatty acid composition

he objective of this study was to determine the effects of feeding fish oil (FO) or stearic acid (ST) on fatty acid (FA) composition of colostrum, milk and plasma in dairy goats during the peripartum period. Starting from the last week of gestation until 3 weeks after kidding, fifteen multiparous Alpine dairy goats were fed two experimental diets (alfalfa, mix hays and a concentrate mix), added either with 30 (before kidding) or 50g/head/d (after kidding) of FA from FO (rich in EPA, C20:5 n-3 and DHA C22:6 n-3) or ST. Blood samples were collected weekly, for determination of total plasma FA composition. Individual colostrum, sampled within the first 24 h postpartum, and milk samples on day 7 and 21, were analyzed for main components. Separate aliquots of colostrum and milk were stored at -20°C and subsequently analyzed by GC to determine FA composition. Data were analysed by GLM or MIXED repeated procedures of SAS9.2. Dietary lipid supplements produced significant changes in plasma FA profile (expressed as g/100g total FA). In particular, EPA and DHA were increased after 21d of supplementation in FO vs ST group (3.96 vs 0.44 for EPA and 2.19 vs 0.76 for DHA). A significant increase of plasma EPA content in FO goats was assessed since 7 d of supplementation. No differences were detected for milk production and milk quality except for a higher milk protein content in ST group. FO enhanced EPA and DHA levels in milk fat both at 7d of lactation (0.32 EPA and 0.25 DHA) and 21 d of lactation (0.46 EPA and 0.21 DHA). Preliminary data evidenced no differences in colostrum possibly because lipid supplementation time before kidding was not enough, but these data need to be confirmed. In conclusion, the present study confirms that modifications of dietary FA composition deriving from the utilization of different dietary lipid sources produce valuable variations of plasma FA profile, starting from 7 d of supplementation. Dietary strategies aiming at enhancing n-3 LC-PUFA concentration in goat milk may be effective. In the present study a greater proportion of EPA and DHA through dietary supplementation with FO has been observed in milk but not in colostrum.