INFLUENCE OF SUPPLEMENTAL FATS ON REPRODUCTIVE TISSUES AND PERFORMANCE OF LACTATING COWS

Fat supplementation (about 3% of dietary dry matter) has often positiv ely influenced the reproductive status of the dairy cow, including inc reased size of the ovulatory follicle, increased numbers of ovarian fo llicles, increased plasma concentration of progesterone, reduced secre tion of prostaglandin metabolite, increased lifespan of the corpus lut eum, and improved fertility. Supplemental fat may allay partially nega tive energy status during the early postpartum period, yet often the p ositive reproductive influence of supplemental fat has been independen t of the energy status of the cow. The fatty acid profile of supplemen tal fats is influential to their impact. Linoleic acid and eicosapenta enoic acid (found in fish meal) are proven inhibitors of cyclooxygenas e in endometrial tissue of dairy cows. As a result, endometrial secret ion of PGF(alpha) can be suppressed, thus potentially preventing early embryonic death. This process may be aided by the effect fat has in s uppressing estradiol-17 beta secretion, thus reducing uterine PGF(2 al pha) secretion and decreasing the sensitivity of the corpus luteum to PGF(2 alpha). Targeting of dietary fatty acids toward ovarian and uter ine function may enhance efficiency of reproductive management and fer tility.