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Biomedical subjects

M Drost

Publications and source records attributed to M Drost.

At least 73 records · Page 4Linked to original sources
PubMed1985

Carry-over effects of periparturient endocrine changes on postpartum reproductive function of Holstein heifers bred to genetically different service sires.

Effects of fetal sire on postpartum reproductive changes of the dam were studied in 21 Holstein heifers whose pregnancy had been initiated by either Angus (n = 7), Holstein (n = 7) or Brahman (n = 7) bulls. After parturition, all heifers were managed uniformly. Heifers in each service-sire-breed group were bled via jugular venipuncture thrice weekly from d 160 to 265 of pregnancy, daily thereafter until 15 d postpartum, and three times per week until d 60 postpartum. Ability of heifers to release prolactin (PRL) and luteinizing hormone (LH) was evaluated on d 10 postpartum after a simultaneous injection of thyrotropin releasing hormone (TRH; 100 micrograms) and gonadotropin releasing hormone (GnRH; 100 micrograms). Between d 5 and 60 postpartum, the reproductive tract of each heifer was examined rectally thrice weekly after collection of blood samples. Basal concentrations of LH from d 1 to 10 postpartum, as well as ability of the pituitary gland to release LH and PRL after the GnRH-TRH challenge, did not differ between service-sire-breed groups (P greater than .1). Means and profiles of progesterone concentrations during the first 60 d postpartum did not differ between service-sire-breed groups (P greater than .1). However, increases in progesterone concentrations following the GnRH-TRH challenge were synchronized more precisely in Angus (P less than .02) than in Holstein- and Brahman-service-sire groups. Daily rates of reduction in cervical and uterine horn diameters were higher (P less than .01) in Holstein- and Brahman- than in Angus-service-sire groups and were associated with higher profiles of postpartum 15-keto-13,14-dihydro-prostaglandin F2 alpha (PGFM) concentrations. Within-cow PGFM concentrations were correlated positively with cervical (r = .36) and uterine horn (r = .32) diameters. Postpartum ovarian responsiveness and uterine involution in Holstein heifers may be affected by genotypes of the conceptus they bore during pregnancy.

Animals↗
PubMed1984

Source of F series prostaglandins during the early postpartum period in cattle.

In vivo and in vitro studies were conducted to determine the contribution of the bovine uterus to concentrations of 15-keto-13,14-dihydro-prostaglandin F2 alpha (PGFM) in peripheral plasma of postpartum cows. In Experiment 1, cows were assigned to three groups: untreated control (n = 4), hysterectomy following a manually induced prolapse of the uterus (n = 5) and sham operation (n = 3: prolapse of the uterus and replacement). Surgery was performed within 8 h of parturition, and blood samples collected frequently on the day of surgery and once (0800 h) or twice (0800 and 1700 h) daily from Day 1 to Day 15 postpartum. Following hysterectomy, PGFM concentrations decreased precipitously, became essentially undetectable by 5 h, and remained so for the rest of the experimental period. In contrast (P less than 0.01), PGFM concentrations, which remained elevated during the day of surgery in the sham-operated group, peaked on Day 2 (sham-operated group: 1339 pg/ml) or Day 3 (untreated control: 2143 pg/ml), and declined to a basal concentration between Days 10 to 15. In Experiment 2, in vitro metabolism of tritiated arachidonic acid ([3H] AA: 10 microCi) and production of PGF2 alpha and PGFM were studied in explants of early postpartum intrauterine tissues (myometrium, caruncle and intercaruncular endometrium). Extracts of [3H] AA metabolites released into the incubation medium were separated on Sephadex LH-20 column chromatography. Metabolites of [3H] AA, having the same chromatographic mobility as PGF2 alpha, PGFM and PGE2, were detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Effects of heat stress during pregnancy on postpartum reproductive changes in Holstein cows.

Effects of heat stress during the last third of gestation on reproductive changes postpartum were studied in Holstein cows. Cows and heifers 160 to 190 d of gestation were assigned in June 1978 to shade (n = seven cows and two heifers) or no shade (n = eight cows and two heifers) management treatments. After parturition, all cows (n = 19) were moved to the milking herd and managed uniformly. On the day of calving and on each Monday, Wednesday and Friday thereafter until d 50 postpartum, jugular blood samples were collected. Beginning approximately 7 d postpartum, the reproductive tract of each cow was examined rectally after collection of blood samples. Estrus was monitored twice daily and cows were inseminated after d 45 postpartum. Prepartum heat stress increased 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) concentrations postpartum and increased the rate of uterine involution. Regardless of prepartum treatment, progesterone concentrations indicated that luteal phases had begun by d 12.4 +/- 1.3 postpartum, which was about 3 d before PGFM was basal. The first luteal phase lasted only 10.7 +/- .9 d. First estrus was not detected until d 32.3 +/- 4.8 postpartum. The previously gravid uterine horn had a negative effect on ovarian volume, diameter of the largest follicle and percentage of ovaries with a corpus luteum. However, prepartum heat stress attenuated this effect. This study indicates that heat stress prepartum had residual effects on postpartum reproductive changes, and that the previously gravid uterine horn exerted some control, which was attenuated by heat stress, over ovarian recrudescense. Even though heat stress prepartum affected sensitive measures of postpartum reproductive function, it did not alter days to first estrus, days open (102.3 +/- 13.1) or services/conception (2.5 +/- .3).

Animals↗
PubMed1983

Embryo transfer in water buffalo (Bubalus bubalis).

A normal, live 35-kg water buffalo bull calf was born 300 days after it was nonsurgically collected as a 7-day blastocyst from a water buffalo donor and transferred nonsurgically to an unrelated water buffalo recipient. The development of estrus synchronization, superovulation and estrus detection methods in water buffalo are described.

Journal Article↗
PubMed1981

Effect of estradiol-17beta on PGF and total protein content in bovine uterine flushings and peripheral plasma concentration of 13, 14-dihydro-15-keto-PGF(2alpha).

Two experiments were conducted to examine the effect of estradiol-17beta (E(2)-17beta) on content of immunoreactive prostagladin F(2)alpha (PGF, ng) and total protein (TUP, mg) in uterine flushings, as well as concentrations of 13, 14-dihydro-15-keto-PGF(2)alpha (PGFM) in plasma (Pg/ml). In experiment 1, Holstein heifers were utilized in a single reversal trial in which either E(2)-17beta (3 mg in 2 ml saline/ethanol 50:50; n=5) or vehicle alone (n=6) were given intravenously on day 14 or 15 of the estrous cycle (Period 1) following an induced estrus (day of estrus = day 0). Treatment (Trt) groups were reversed in Period 2 (Day 14 or 15 of the second estrous cycle). Jugular venous plasma was obtained before treatment (Oh), and at 5, 6, and 9h posttreatment (PT). Uterine flushings were collected nonsurgically in vivo , per cervix, via Foley catheter at 6h PT (20 ml of .9% saline per uterine horn). E(2)-17beta did not significantly alter (E(2)-17beta vs vehicle; x(-) +/- S.E.M.) PGF (1674 +/- .11 +/- 338.39 vs 1889.91 +/- 400.24 ng; P> .10) or TUP (33.25 +/- 2.57 vs 39.16 +/- 3.04 mg; P > .10). However, E(2)-17beta increased (P < .05) plasma PGFM (E(2)-17beta vs vehicle) after treatment (0h, 113.2 vs 163.8; 5h, 312.5 vs 203.9; 6h, 324.5 vs 198.0; 9h, 323.2 vs 246.8, pg/ml). In experiment 2, crossbred beef cattle received comparable treatments of either E(2)-17beta (n=5) or vehicle (n=5) on day 14 or 15 postestrus. Jugular venous plasma was obtained at 0h PT, and at 6h PT. Uterine flushings (1.9% saline, 20 ml per uterine horn) and peripheral plasma were collected at slaughter. Estradiol-17beta increased PGF (30.07 +/- 5.94 vs 8.46 +/- 2.01 ng; P> <.05) in uterine flushings as well as PGFM in plasma (E(2)-17beta : 55.82 +/- 19.13 pg/ml, at 0h and 89.31 +/- 14.02 pg/ml, at 6h, vs saline: 103.46 +/- 50.73 pg/ml, at 0h and 17.78 +/- 14.22, at 6h). Estradiol-17beta stimulated uterine production and release of PGF and protein as measured in flushings (experiment 2) as well as plasma PGFM responses (experiments 1 and 2). Uterine and/or cervical stimulation of experiment 1 may have masked uterine response to E(2)-17beta.

Journal Article↗
PubMed1975

A field study on embryo transfer in cattle.

Thirty-five 4-day-old embryos were surgically collected from 5 Fleckvieh and 3 Gelbviehheifers. The embryos were transported by air on the same day to a distant rach where 34 embryos were surgically transferred via the flank into recipient cows. Nineteen recipient cows were diagnosed pregnant at approximately 50 days.

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