An increase in serum lipids increases luteal lipid content and alters the disappearance rate of progesterone in cows

Abstract

To determine whether an increase in serum lipids alters the area occupied by lipid droplets in steroidogenic luteal cells and(or) clearance rates of progesterone from serum, pregnant beef heifers received control (n = 6) or treatment (n = 5) diets. To increase serum lipids, the treatment diet contained calcium soaps of fatty acids. Control and treatment diets were formulated to be isocaloric and isonitrogenous. Feeding of diets was initiated approximately 100 d before parturition and continued through the third postpartum estrous cycle. On d 12 or 13 of the third postpartum cycle, corpora lutea were collected by ovariectomy and a center slice was processed for electron microscopy. Eight samples from each slice were sectioned, stained, and examined at a magnification of 2,500x. Five micrographs per sample were analyzed for area occupied by small (SLC) and large (LLC) luteal cells, percentage of the area of each steroidogenic cell type occupied by lipid, and total steroidogenic area (SLC + LLC) occupied by lipid. Jugular blood was collected before and after ovariectomy, and progesterone, cholesterol, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) were quantified. Cows consuming treatment diets had approximately twice (P < .05) the concentration of cholesterol, HDL, and progesterone in serum that controls had. The percentage of the area of SLC, LLC, and total area occupied by lipid was greater (P < .05) in treated than in control cows. The average time required for serum concentrations of progesterone to decrease by 50% after ovariectomy was greater (P < .05) in treated than in control cows (170 +/- 16 vs 113 +/- 15 min).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of supplementation of calcium salts of polyunsaturated fatty acids on serum concentrations of progesterone and insulin of pregnant dairy cows

“…Those authors concluded that the plasma concentrations of LNA (less than 8 µM) after the linseed oil infusions were not sufficient to inhibit the key enzymes responsible for P 4 metabolism (P450 2C and P450 3A) and thus, did not decrease hepatic clearance of P 4 . Hawkins et al (1995) reported increased serum concentrations of P 4 in pregnant heifers when calcium salts of FA were fed at 0.57 kg/heifer daily. Fouladi-Nashta et al (2007) only observed a tendency for greater P 4 concentrations when lactating dairy cows were fed 0.80 kg/d of calcium salts of FA compared with 0.20 kg/d.…”

“…Adding calcium soaps of FA to the diet increased serum concentrations of P 4 in bovine females (Hightshoe et al, 1991;Hawkins et al, 1995). Greater concentrations of P 4 before and after breeding are associated with enhanced fertility (Folman et al, 1973) and embryonic survival (Mann et al, 2006).…”

“…Linoleic acid is a precursor for the synthesis of arachidonic acid, which may increase mitochondrial uptake of cholesterol (Stocco and Clark, 1996), and thus, increase P 4 synthesis (Grummer and Carroll, 1991). Also, PUFA supplementation may decrease the hepatic metabolism of P 4 (Hawkins et al, 1995). However, limited information exists regarding the effects of relatively small amounts of PUFA supplementation on circulating concentrations of P 4 in dairy cows (Reis et al, 2012).…”

The effect of nutrition and metabolic status on the development of follicles, oocytes and embryos in ruminants

“…Several studies have suggested that supplementation of cattle with PUFAs increased the plasma concentrations of steroid by stimulating ovarian production of steroid hormones through various mechanisms, including increased availability of lipoprotein-cholesterol (Hawkins et al, 1995;Lammoglia et al, 1996), modulation of prostaglandin synthesis (Knickerbocker et al, 1986), and the direct stimulation of ovarian steroidogenesis (Staples et al, 1998). In another study on cows, it was shown that diets enriched in n-6 PUFAs increased the secretion of progesterone by the granulosa cells (Wehrman et al, 1991).…”

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

“…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].…”