Paracrine and endocrine actions of interferon tau (IFNT).

This review focuses on the paracrine and endocrine actions of interferon tau (IFNT) during pregnancy recognition and establishment in ruminants. Pregnancy recognition involves the suppression of the endometrial luteolytic mechanism by the conceptus to maintain progesterone production by the corpus luteum (CL). The paracrine antiluteolytic effects of conceptus-derived IFNT inhibit upregulation of oxytocin receptors in the endometrial epithelia of the uterus, thereby preventing the production of luteolytic prostaglandin F2 alpha (PGF2α) pulses. In the endometrium, IFNT induces or upregulates a large number of classical IFN-stimulated genes (ISGs) and regulates expression of many other genes in a cell-specific manner that are likely important for conceptus elongation, implantation and establishment of pregnancy. Further, IFNT has endocrine effects on extrauterine cells and tissues. In sheep, IFNT induces luteal resistance to PGF2α, thereby ensuring survival of the CL for maintenance of pregnancy. The ISGs induced in circulating peripheral blood mononuclear cells by IFNT may also be useful as an indicator of pregnancy status in cattle. An increased knowledge of IFNT and ISGs is important to improve the reproductive efficiency in ruminants.

Effects of supplementation with docosahexaenoic acid on reproduction of dairy cows.

The objectives were to determine the effects of supplementing docosahexaenoic acid (DHA)-rich algae on reproduction of dairy cows. Holstein cows were assigned randomly to either a control (n = 373) or the same diet supplemented daily with 100 g/cow of an algae product containing 10% DHA (algae, n = 366) from 27 to 147 days postpartum. Measurements included yields of milk and milk components, fatty acids (FA) profiles in milk fat and plasma phospholipids, resumption of ovulation by 57 days postpartum, pregnancy per artificial insemination (AI) and expression of interferon-stimulated genes in leukocytes. Feeding algae increased resumption of estrous cyclicity (77.6 vs 65.9%) and pregnancy at first AI (47.6 vs 32.8%) in primiparous cows. Algae increased pregnancy per AI in all AI in both primiparous and multiparous cows (41.6 vs 30.7%), which reduced days to pregnancy by 22 days (102 vs 124 days) compared with control cows. Pregnant cows fed algae had greater expression of RTP4 in blood leukocytes compared with those in pregnant control cows. Feeding algae increased the incorporation of DHA, eicosapentaenoic acid, conjugated linoleic acid isomers cis-9 trans-11, trans-10 cis-12 and total n-3 FA in phospholipids in plasma and milk fat. Yields of milk and true protein increased by 1.1 kg/day and 30 g/day respectively, whereas fat yield decreased 40 g/day in algae compared with that in control. Supplementing DHA-rich algae altered the FA composition of lipid fractions and improved reproduction in dairy cows. The benefits on reproduction might be mediated by enhanced embryo development based on changes in interferon-stimulated gene expression.