In spite of the difficulties in delivering PUFA to ruminants, studies have generally indicated that the PUFA of the omega-6 (linoleic acid) and omega-3 [α-linolenic acid; eicosapentaenoic (EPA), C20:5 omega-3; docosahexaenoic (DHA), C22:6 omega-3] families are the most beneficial to improving reproduction in cows. The objectives were to determine if a diet enriched in α-linolenic acid (omega-3) or linoleic acid (omega-6) would influence milk production and composition, metabolic status, and reproductive performance in lactating dairy cows. High-yielding multiparous Holstein dairy cows (n = 120) with no overt clinical illnesses were blocked according to calving date and parity. Cows were assigned randomly to be fed 1) soybean whole roast (Soy, omega-6, n = 40) or 2) linseed (Lin, omega-3, n = 40) or 3) palm oil as a source of SFA (PO, n = 40) from calving until first heat after 40 d postpartum (dpp), and then half of the cows in each treatment group were switched to receive either Lin or SFA (PO) from first heat after d 40 to 120 dpp. Blood was collected from a subsample of cows. Blood was collected at 14 d intervals for 12 wk, starting on the day of calving. Results showed milk yield and DMI were not affected. Milk compositions were similar (P > 0.08) among diets, except concentration and yield of milk fat percentage, which was less in cows fed Lin (P < 0.05). Uterine involution in cows fed Soy occurred earlier (P < 0.05). Diets affected day to first estrus and day to first insemination in cows (P < 0.05). There were no differences among treatments for percent heat detection, percent pregnancy per first insemination, and percent conception per AI at estrus. Also, there is a trend of pregnancy by 120 d, which is 66.7% for the Lin group vs. 50.91% for the PO group (P < 0.08). Of the 4 pregnancy losses, 2 occurred in PO-PO group and 2 occurred in Soy-PO group, and none occurred in the other 4 treatments. In conclusion, our study showed feeding omega-6 fatty acids during 40 dpp could be a good treatment for early postpartum periods, and a shift to omega-3 fatty acids until 40 d after AI can be considered as a strategy for improving fertility in lactating dairy cows Copyright © 2013. American Society of Animal Science .

Although the various members of the fibroblast growth factor (FGF) family are generally mitotic, one member, FGF18, has been shown to increase the rate of apoptosis of ovarian granulosa cells. In the present study, we first determined whether granulosa cells express FGF18 and we then explored the mechanism through which FGF18 increases apoptosis in vitro. Under culture conditions that favored estradiol secretion and CYP19A1 expression, granulosa FGF18 mRNA levels were barely detectable; however, withdrawing gonadotropic support (follicle-stimulating hormone or insulin-like growth factor 1) reduced levels of CYP19A1 mRNA and increased abundance of mRNA encoding the death ligand FASLG and FGF18. Addition of FGF18, but not FGF2, FGF10, or EGF, increased the proportion of apoptotic cells and frequency of caspase 3 activation, and these effects were abrogated by coculture with estradiol. Addition of FGF18 decreased abundance of mRNA encoding the antiapoptotic proteins GADD45B and MDM2, and increased that encoding the proapoptotic protein BBC3; these effects were reversed by coculture with estradiol. The physiological relevance of FGF18 was determined using an in vivo model: injection of FGF18 directly into growing bovine dominant follicles caused cessation of follicle growth by 24 h after injection. Collectively, these data demonstrate that FGF18 is proapoptotic in vivo and may act through a mechanism involving the BBC3-MDM2 pathway.

This study was done to investigate the effect of feeding linseed on blood metabolites, incidence of cystic follicles, resumption of postpartum ovarian cyclicity, pregnancy rate, milk production, and composition in fresh Holstein dairy cows. A total of 399 dairy cows were assigned randomly to 2 diets. Diets contained either protected palm oil (CON) or extruded linseed (LIN) and were fed from calving to d 40 postpartum. Ovaries of each cow were examined on d 10, 20, 30, and 40 after parturition (parturition=d 0) by transrectal ultrasonography to determine follicular development, ovarian disorders, and cyclicity. Blood samples were collected at 14-d intervals for 6 wk starting on the day of parturition to determine plasma concentrations of glucose, β-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and blood urea N (BUN). Results showed plasma glucose concentration was affected by the diets and was greater in the LIN treatment, but BHBA, NEFA, and BUN concentrations were similar among treatments. Dietary treatments had no significant effect on milk production and composition except milk fat percentage that significantly decreased in cows fed LIN (3.55%) compared with those fed with CON (4.17%). Plasma progesterone concentrations were greater in LIN treatment than CON treatment (1.31±0.09 vs. 0.87±0.09) at early postpartum. The resumption of cyclicity and onset of estrus were influenced by treatments and reduced by 7 d in LIN treatment compared with CON treatment. Cows fed diets enriched in LIN fatty acids had a lesser incidence of cystic follicles. Treatments did not differ significantly in terms of the number of days open, number of services per pregnancy, and pregnancy rate. In conclusion, feeding linseed immediately after parturition decreased milk fat and incidence of cystic follicles, increased progesterone concentrations early postpartum, and caused earlier resumption of cyclicity but did not affect pregnancy rate.

In dairy cows, subjected to a G6G protocol, objectives were to determine effects of (1) extending the interval from prostaglandin F2α (PGF2α) to gonadotropin-releasing hormone (GnRH) during presynchronization; and (2) adding a second PGF2α treatment before artificial insemination (AI), on ovarian response, plasma progesterone (P4) concentrations and pregnancy per AI (P/AI). In a 2×2 factorial design, lactating cows were randomly assigned to one of four timed AI (TAI) protocols: (1) G6G (n=149), one injection of PGF2α, GnRH 2 days later and a 7-day Ovsynch (GnRH, 7 days, PGF2α, 56 h, GnRH, 16 h, TAI) was initiated 6 days later; (2) G6GP (n=144), an additional PGF2α treatment (24 h after the first) during Ovsynch of the G6G protocol; (3) MG6G, one injection of PGF2α, GnRH 4 days later before initiation of the G6G protocol; and (4) MG6GP, an additional PGF2α treatment (24 h after the first) during Ovsynch of the MG6G protocol. Blood samples were collected (subset of 200 cows) at first GnRH and PGF2α of the Ovsynch, and at TAI to measure P4. Ultrasound examinations were performed in a subset of 406 cows to evaluate ovarian response at various times of Ovsynch, and in all cattle to determine pregnancy status at 32 and 60 days after TAI. Extending the interval by 2 days between PGF2α and GnRH during presynchronization increased (P<0.01) ovulatory response to first GnRH of Ovsynch, circulating P4 during Ovsynch, and P/AI at 32 and 60 days after TAI. Adding a second PGF2α treatment before AI increased the proportion of cows with luteal regression (P=0.04), improved P/AI at 60 days after TAI (P=0.05), and reduced pregnancy loss between 30 and 60 days after TAI (P=0.04). In summary, extending the interval from PGF2α to GnRH during presynchronization increased response to first GnRH of Ovsynch and P4 concentrations during Ovsynch, whereas adding a second PGF2α treatment before AI enhanced luteal regression. Both modifications of the G6G protocol improved fertility in lactating dairy cows.