Plasma fatty acids, prostaglandin F2alpha metabolite, and reproductive response in postpartum heifers fed rumen bypass fat.

Abstract

An experiment was conducted to determine whether feeding rumen-protected fatty acids (FA) to postpartum heifers would increase plasma concentrations of linoleic acid and PGF2, metabolite (PGFM), shorten the interval from calving to first increase in plasma concentrations of progesterone (P4), and increase pregnancy rate relative to controls. Hereford x Angus heifers (346 kg) were assigned randomly to treatments containing either lipid or barley supplemented diets for the first 30 d postpartum. Lipid was .23 kg.heifer(-1).d(-1) of calcium salts of FA (CSFA; n = 20), and an isocaloric amount of barley served as the control (n = 19). Supplements, with .23 kg of barley as a vehicle, and a basal diet of meadow and alfalfa hays were pen fed to heifers (5/pen). Heifers were bled on alternate days (d1 to 30) and twice weekly (d 30 to 2 wk after first estrus) for RIA of plasma PGFM and P4, respectively. Weight percentage of major FA in plasma on d1 and 7 was determined with gas chromatography. First behavioral estrus was detected by use of intact bulls and confirmed by an increase in plasma P4. On d 7, but not d 1, plasma from heifers fed CSFA had altered proportions of major FA (P< .01), including an increase in linoleic acid compared with those of controls (29.1 vs 25.6% of total FA; SE = .75; P < .01). Analysis of variance of contrast variables revealed an effect of treatment on direction of change in PGFM from d 3 to 5 (P < .01). By d 7 and on d 9, plasma concentrations of PGFM were greater in heifers fed CSFA than in controls (P = .02 and P = .06, respectively). There was no difference in plasma concentration of PGFM between treatments on d 1, 3, 5, 11, 13, and 15 postpartum (P = .80, .17, .52, .82, .46, and .77, respectively). Days to first estrus with ovulation, pregnancy rate, and calving interval were not affected by treatments (P = .58, .52, and .24, respectively). Although supplemental lipid fed to primiparous beef heifers increased plasma levels of linoleic acid and production of PGFM in the early postpartum period, it did not improve the fertility of these heifers in the subsequent breeding season.

Effect of dietary enrichment with either n-3 or n-6 fatty acids on systemic metabolite and hormone concentration and ovarian function in heifers

“…The similarity in daily DMI across diets was mirrored in animal performance with no effect on ADG, consistent with the report of Wistuba et al (2006). Despite evidence of a diet 3 day interaction for plasma concentrations of some FA measured, concentrations of most FA were generally consistent with other published reports (Filley et al, 2000;Burns et al, 2003) involving similar dietary approaches. Consequently, rather than discussing the effect of diet on each FA measured, we focus on a select number of FAs in the context of their potential biological roles in metabolism and reproduction.…”

“…Consequently, rather than discussing the effect of diet on each FA measured, we focus on a select number of FAs in the context of their potential biological roles in metabolism and reproduction. The addition of the whole soya beans increased the concentrations of linoleic acid in plasma consistent with other studies involving dietary supplementation of cattle with a source of linoleic acid (Filley et al, 2000;Burns et al, 2003). The linoleic acid content of cattle follicular fluid and of oocytes is apparently important for oocyte developmental competence (Homa and Brown, 1992) and has been shown to be important for blastulation in in vitro fertilisation studies (Zeron et al, 2001).…”

Dietary supplementation with safflower seeds differing in fatty acid composition differentially influences serum concentrations of prostaglandin F metabolite in postpartum beef cows

“…Similarly, Brahman cows supplemented with 530 g·d -1 lipid from rice bran containing approximately equal proportions of oleic and linoleic acid tended to have increased concentrations of serum PGFM [4]. Likewise, beef cows fed 230 g·d -1 calcium soaps of fatty acids containing 40% oleic and 9% linoleic acid also had increased concentrations of PGFM early in the postpartum period [5].…”

“…High serum concentrations of PGFM early postpartum decreases the time required for uterine involution [20]. Filley et al [5] reported a negative correlation between the duration of increased PGF 2α production and the duration of the postpartum anestrous period. Conversely, high serum concentrations of PGF 2α later in the postpartum interval may reduce subsequent fertility by increasing the incidence of estrous cycles with abbreviated luteal phases resulting in early embryonic mortality [10,21,25].…”

“…In addition to helping meet energy demands, supplemental lipids influence reproductive performance in bovine females. Supplementing cows with dietary lipid increased concentrations of serum lipids [1,2], altered ovarian follicular development [2,3], and prostaglandin (PG) synthesis [4][5][6]. In late-pregnant ewes, diets high in linoleic acid increased plasma concentrations of arachidonic acid [7] and production of PG from endometrial tissue [7,8].…”