Fat supplementation (about 3% of dietary dry matter) has often positively influenced the reproductive status of the dairy cow, including increased size of the ovulatory follicle, increased numbers of ovarian follicles, increased plasma concentration of progesterone, reduced secretion of prostaglandin metabolite, increased lifespan of the corpus luteum, and improved fertility.
Supplemental fat may allay partially negative energy status during the early postpartum period, yet often the positive reproductive influence of supplemental fat has been independent of the energy status of the cow. The fatty acid profile of supplemental fats is influential to their impact. Linoleic acid and eicosapentaenoic acid (found in fish meal) are proven inhibitors of cyclooxygenase in endometrial tissue of dairy cows. As a result, endometrial secretion of PGFa can be suppressed, thus potentially preventing early embryonic death. This process may be aided by the effect fat has in suppressing estradiol- 17b secretion, thus reducing uterine PGF2a secretion and decreasing the sensitivity of the corpus luteum to PGF2a. Targeting of dietary fatty acids toward ovarian and uterine function may enhance efficiency of reproductive management and fertility.
Abbreviation key: BCS = body condition score, Ca- LCFA = calcium soaps of long-chain fatty acids, CL = corpus luteum, ES = energy status, HDL = high density lipoproteins, PGFM = 13, 14-dihydro- 15-keto PGF2a metabolite, PP = postpartum.