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Biomedical subjects

R A Dailey

Publications and source records attributed to R A Dailey.

At least 73 records · Page 4Linked to original sources
PubMed1986

Age, dose of FSH and other factors affecting superovulation in Holstein cows.

Effects of age of donor and other factors on superovulation and production of transferable embryos were investigated. Data were obtained on 987 recoveries of embryos performed between November 1980 and June 1984 by Select Embryos, Inc. The 339 Holstein donors ranged in age from 1.8 to 17.8 yr. The effects of age of donor and dose of follicle stimulating hormone (FSH) were examined using regression analysis. For on-farm recoveries, numbers of embryos, rates of fertilization, quality scores of all embryos and numbers of transferable embryos decreased (P less than .01, P less than .001, P less than .05, P less than .01, respectively) with increasing age of donor. For in-clinic recoveries, numbers of embryos plus ova recovered were affected by age of donor, dose of FSH and the interaction of the two (P less than .05). Among older donors, increasing doses of FSH were associated with an increase in the number of ova plus embryos recovered. However, among younger donors, increasing doses of FSH had a negative effect. Numbers of embryos, rates of fertilization and numbers of transferable embryos decreased (P less than .05) with advancing age and increased (P less than .05) with increasing doses of FSH. Greater numbers of ova plus embryos were recovered when treatment with FSH was begun on d 10 or 11 as compared with d 7, 8, 9, 12, 13 or 14 (P less than .001). It was concluded that an increase in age of donor had a negative influence on the success of superovulation and the production of transferable embryos, and that the response to FSH was affected by age of donor.

Animals↗
PubMed1986

Synchronization of estrus in dairy cows with prostaglandin F2 alpha and estradiol benzoate.

A field study using 322 lactating dairy cows in seven commercial and two university herds was conducted to determine if treatment with estradiol benzoate 40 to 48 h after treatment with prostaglandin F2 alpha would enhance synchronization of estrus. Estrogen treatment tended to increase the proportion of cows in estrus within 5 d (synchronized) after prostaglandin treatment (66.9% versus 58.9%). Of synchronized cows, a greater proportion treated with estrogen (66.9%) were in estrus on d 3 than those not receiving estrogen (48.2%). First service conception rate (31.9%) and interval to second service (35.6 d) were not affected by treatment with estrogen. Milk progesterone was measured in university herds. More cows with milk progesterone concentrations greater than or equal to 8 ng/ml were synchronized (75.4%) than those with less than 8 ng/ml (63.3%). Treatment with estrogen increased synchrony of cows with high progesterone (90.3%) more than prostaglandin alone (60.0%). Based on progesterone concentrations at breeding and 22 to 24 d later, estimated conception rate was 58.7%, and net conception rate based on palpation was 41.3%. Tighter synchrony of estrus can be achieved by using estradiol benzoate 40 to 48 h after prostaglandin. Concentrations of milk progesterone might predict success of treatment.

Animals↗
PubMed1985

Uterine involution and postpartum ovarian activity in Nili-Ravi buffaloes.

Uterine involution and postpartum ovarian activity were studied in 53 Nili-Ravi buffaloes. Mean intervals to uterine involution (26 days), regression of the corpus albicans of pregnancy (22 days), resumption of follicular activity (21 days) and first postpartum estrus (56 days) were not affected by the month of calving or age. Mean interval to formation of first corpus luteum (CL) after calving as indicated by progesterone in plasma (>/= 1.5 ng/ml) was 23.8 +/- 1.7 days, but only 52% of these CL were palpable. The number of CL formed before first postpartum estrus ranged from zero to five per buffalo; mean values based upon progesterone and palpation were 1.6 +/- 1.3 and 0.8 +/- 0.2, respectively. Based upon either progesterone or palpation, length of first postpartum luteal phase (7.9 or 6.6 days) was shorter than the luteal phase immediately preceeding the first estrus (12.1 or 8.9 days). Intervals from regular cyclic ovarian activity was not established until first estrus and intervals from the end of one luteal phase to the onset of the next were as long as three weeks. High concentrations of progesterone (>/= 1.5 ng/ml) on the day of behavioral estrus were seen in 23% of the buffaloes studied.

Journal Article↗
PubMed1985

Longitudinal study of the surge of gonadotropins induced by exogenous hormones in prepuberal gilts.

The transition at puberty to adult hormonal patterns has been hypothesized to involve a shift in the sensitivity of the hypothalamic-hypophysial axis to hormonal stimulation. Prepuberal gilts were treated with GnRH or estradiol-benzoate (EB) to compare responsiveness of the pituitary at 40, 80, 120, and 160 days of age. Mean BW at each was 15.6, 36.3, 56.4, and 70.7 kg, respectively. Gilts were injected with GnRH (625 ng/kg; iv) or EB (600 micrograms/kg; im) or with vehicles. Blood samples were collected at 10-min intervals for 3 h after injection of GnRH or vehicle or 4-h intervals for 96 h after injection with EB or vehicle. Plasma concentrations of LH and FSH were measured by RIA, and data were analyzed by a general linear model for split plot design. Pretreatment basal concentrations of LH and FSH decreased between 40 and 160 days of age from 1.7 to less than 0.7 ng/ml and from 29.9-4.1 ng/ml, respectively. GnRH-induced surges of LH became more synchronous relative to time of injection and decreased in maximum concentration with age. In the youngest gilts, multiple surges of LH were released after a single injection of GnRH. The magnitude of the initial release of LH decreased with age from 5.6-2.7 ng/ml. Gilts treated with EB had two or more surges of LH at all ages. However, the concentration of the surge was greatest and occurred synchronously 12 h earlier in the 160-day-old gilts than at other ages. Therefore, sensitivity to EB was enhanced both in response time and amount of LH released. Concentrations of FSH were highly variable among gilts, and treatment with GnRH or EB induced an adult-like release of gonadotropins only at 160 days of age. Maturation of the surge mechanism involved at least two distinct alterations for LH. First there was a reduction in the amount of LH released in response to GnRH after day 40. Second an increase in the precision (timing) and magnitude of the surge of LH in response to EB was seen as gilts approached puberty.

Animals↗
PubMed1985

Survey of nutritional management practices and metabolic disorders in West Virginia dairy herds.

Sixteen farmers, representing three major dairy counties in West Virginia, were interviewed to determine current dairy management practices. Herd health records were used to determine the incidence of metabolic and digestive disorders. All feedstuffs used on these farms were sampled for chemical analyses. The total number of cows on the 16 farms surveyed was 1870 with an average herd size of 117 and 6387 kg milk produced per cow per year. Fourteen of the 16 farmers used forage testing services, obtained professional advice on feeding and nutrition, and attempted to feed according to production. Eleven of sixteen farmers increased grain 2 weeks prior to calving and all gradually adjusted the intake of grain to cows recently freshened. Ration imbalance problems included both excesses and deficiencies of energy, protein, phosphorus, and calcium. Excess calcium, phosphorous, and crude protein were correlated (P less than .01, r2 = .74) with the incidence of fat cows. The incidence of metabolic disorders in these herds was low to average and the most prevalent management problem encountered was low butter fat.

Animal Husbandry↗
PubMed1985

Factors affecting reproductive performance of dairy cows.

We conducted two studies to determine how herd management practices and traits of individual cows affect performance of the herd and of the cow within a herd. Management practices, reproductive performance of the herd, and relationships between management and reproductive performance were characterized on 83 dairy farms with 7596 cows. Data included 21 management variables (e.g., facilities, herd health program, estrous detection program) and 8 performance variables obtained from Dairy Herd Improvement or unofficial records (e.g., size of herd, production, days open). Although varying among herds, annual average herd incidences of reproductive disorders and reproductive performance were similar to those reported. Managerial practices influenced incidences of retained placenta and uterine infection, days open of cows not bred and of all cows, services per conception, and percentages of herd open more than 100 days and culled for low production. Veterinarian was the most consistent variable influencing herd reproductive performance. Data also were collected from production and lifetime records of 2532 cows in 19 herds. Reproductive performance was affected by season of calving, production, maturity, and reproductive disorders. Several cows with extremely poor reproductive records were maintained.

Animal Husbandry↗
PubMed1984

Compensatory responses after unilateral ovariectomy in rabbits.

Compensatory ovarian and gonadotropic responses to unilateral ovariectomy (ULO) were examined in the rabbit doe, an induced ovulator. On Days 2, 4, 5, 6, 8, 10, 15 and 20 after ULO, ovaries from 3 hemiovariectomized does and 1 sham-hemiovariectomized doe were examined macro- and microscopically for number, size and signs of atresia of follicles. The number of surface follicles increased initially to 7 or 8 follicles 2 days after ULO, followed by an increase to 10 or more follicles by Day 15 (control ovaries had 5.7 +/- 0.4 follicles). Total numbers of antral follicles and the proportion of follicles which were atretic did not vary relative to day after ULO. However, distributions of antral follicles in classes of 0.2-mm increments were significantly different between sham-ovariectomized and hemiovariectomized does after Day 2 due to shifts of follicles into larger size classes. Peripheral serum concentrations of follicle-stimulating hormone (FSH), but not luteinizing hormone (LH), increased temporarily during the 48 h after ULO. Follicular compensation after ULO in the doe entailed nonlinear increases in numbers of preovulatory follicles, due to increased growth within the antral population of follicles, probably the result of an acute surge of FSH. A period of more than 10 days was necessary to restore the number of preovulatory follicles after ULO. Exogenous human chorionic gonadotropin (hCG) induced ovulation of recruited follicles.

Animals↗
PubMed1984

Relationships between LH and estradiol-17 beta after removal of luteal progesterone in the ewe.

Three experiments were conducted to examine the relationship between systemic concentrations of luteinizing hormone (LH) and estradiol-17 beta (E2) after withdrawal of progesterone in cycling ewes. In Exp. 1, ewes were assigned randomly to one of three treatments: laparotomy (C), removal of the luteal ovary (ULO), or ULO plus anesthesia with sodium pentobarbital for 6 h beginning 4 h after surgery. Anesthesia was used in an attempt to block the expected increase in tonic secretion of LH. Patterns of LH and E2 in these three groups did not differ during the 24-h experimental period. In Exp. 2, a longer period of anesthesia was utilized. Forty-eight ewes were assigned at random to one of four treatments: C, ULO, lutectomy or an intrafollicular injection of prostaglandin F2 alpha (PGF2 alpha). One-half of the ewes in each group were anesthetized with sodium pentobarbital from initiation of treatment (0 h) until 10 h after surgery. Sodium pentobarbital did not suppress the increases in LH and E2 after progesterone withdrawal. The regression of concentrations of E2 on concentration of LH was not significant. In Exp. 3, ewes were infused with either saline or dopamine after receiving an im injection of PGF2 alpha. Tonic secretion of LH increased after 4 h in ewes infused with saline, but not in ewes infused with dopamine. Despite the suppression of LH, concentrations of E2 increased in dopamine-treated ewes as in control ewes. Therefore, the initial increase in E2 after a decline of progesterone in cycling ewes is independent of increases in LH.

Anesthesia↗
PubMed1984

Factors affecting ovarian compensation after unilateral ovariectomy in gilts.

Two experiments were conducted to identify the temporal limits of an ovarian compensatory response after unilateral ovariectomy (ULO) in gilts and to examine ovarian and hormonal factors that might be related to this response. In the first study, all eight gilts that were unilaterally ovariectomized on d 12, 14 or 16 of an estrous cycle and two of four ULO on d 18 had a significant compensatory increase in ovulation rate per ovary compared with controls. Ovulatory compensation failed to occur, however, in two of four and four of four gilts ULO on d 18 or 19 of an estrous cycle, respectively. In the second study, blood samples were collected from 26 gilts beginning on d 14 of an estrous cycle, and animals were assigned to sham-surgery or ULO on d 17, 18 or 19. Ovarian compensation occurred after ULO on all 3 d of surgery in the second study, but most follicles failed to ovulate and formed large luteinized cysts. The ability to compensate was related positively to the number of medium-sized follicles on the intact ovary at the time of ULO, to an increase in concentrations of follicle-stimulating hormone 12 to 18 h after ULO and to the interval from ULO to the preovulatory surge of luteinizing hormone. In a third experiment, interruption of the ovulatory mechanism and development of cystic follicles similar to those observed in the second study were induced simply by physical manipulation of the d 19 preovulatory ovary while contralateral untouched ovaries ovulated normally.

Animals↗
PubMed1984

Effect of low and high fill diets on dry matter intake, milk production, and reproductive performance during early lactation.

Feedstuffs analyzed for rate and extent of ruminal neutral detergent fiber disappearance were used to formulate two diets that differed for predicted time required for ruminal clearance of neutral detergent fiber. Diets with slow and fast estimated disappearance rate of neutral detergent fiber were termed and high and low fill, respectively. For both diets, crude protein, acid detergent fiber, neutral detergent fiber, net energy of lactation, and soluble protein were similar. Twenty-eight lactating cows were limit fed the rations 2 wk prior to calving, then fed for ad libitum consumption until 8 wk after calving. Cows fed low fill produced more milk (30.3 vs. 26.3 kg) and milk protein (.97 vs. .78 kg) and had higher incidence of short estrous cycles and fewer acyclic cows by 8 wk postpartum than cows offered high fill. Dry matter intake, fat-corrected milk yield, daily fat production, and solids-not-fat did not differ between diets. Rumen fermentation measurements for pH and ammonia-nitrogen concentrations were also not different between diets. Cows fed low fill tended to have higher rates of solids and liquid turnover and lower total dry matter in the rumen compared with cows fed high fill. Low ruminal pH on both diets as well as other physiological mechanisms may have been responsible for failure of rates of neutral detergent fiber disappearance to affect intake of dry matter.

Animals↗
PubMed1983

Effects of dopamine and serotonin on concentrations of luteinizing hormone and estradiol-17 beta in plasma of cycling ewes.

Effects of 0, 0.66 and 6.6 micrograms/kg per min of dopamine (DA) and of 0, 0.06 and 0.66 micrograms/kg per min of serotonin (5-HT) on secretion of luteinizing hormone (LH), estradiol-17 beta and progesterone were examined in ewes during luteal regression and the follicular phase. Onset of luteolysis was synchronized with two injections of 7.5 mg prostaglandin F2 alpha (PGF2 alpha) (i.m.) given 3 h apart in ewes which were 12-14 days postestrus. Ewes were infused intravenously with DA, 5-HT or a combination of DA and 5-HT for a 60-h period beginning at the time of the first PGF2 alpha injection. Neither DA nor 5-HT influenced the decrease in plasma concentrations of progesterone following PGF2 alpha. Effects of DA and 5-HT on tonic secretion of LH changed during the infusion. During the first 12 h, increasing doses of DA depressed and increasing doses of 5-HT increased mean concentrations of LH in plasma in a linear manner (DA, P less than 0.01; 5-HT, P less than 0.05). Between 16 and 34 h, 6.6 micrograms/kg per min of DA continued to suppress LH, however, 5-HT was no longer stimulatory to secretion of LH. DA was unable to inhibit secretion of LH after 40 h. Also, between 0 and 34 h, concentrations of estradiol-17 beta in plasma were decreased by infusion of DA (P less than 0.01). Interval from PGF2 alpha to onset of the preovulatory surge of LH, magnitude of the surge and duration of the surge were not altered by infusion of either DA or 5-HT.

Animals↗
PubMed1983

Effects of repeated removal of large ovarian follicles and treatment with progestin on ovarian function in the ewe.

Preovulatory follicles were removed from ewes during estrus to determine hormonal, ovarian and behavioral responses. In Experiment 1, new follicles were recruited and ovulated within 4 days, and a second estrous period was observed in most ewes. In Experiment 2, follicles were removed at Day 0 (estrus), Day 3.5 and Day 7.0 to determine responses to repeated follicular removal in the absence of a corpus luteum (CL). Ewes in two groups were given exogenous progestin at the time of first or second surgery. Each follicular removal was followed by a surge of follicle-stimulating hormone (FSH) and follicular growth, and in many cases, behavioral estrus and/or a surge of luteinizing hormone (LH) was detected around the time of the next follicular removal. Although not necessary for display of estrus, treatment with progestin during follicular maturation increased the number of ewes showing estrus. When the newly developing follicles were allowed to ovulate, resulting corpora lutea produced low levels of progesterone or had a short life span.

Animals↗
PubMed1983

First luteal tissue in ewe lambs: influence on subsequent ovarian activity and response to hysterectomy.

Two experiments were conducted in peripuberal ewe lambs to determine (a) the influence of the first luteal structure [most frequently a transient (i.e., 1 to 4 d) structure] on subsequent ovarian activity and (b) a role for the uterus in its demise. In Exp. 1, 21 lambs were assigned randomly on the day of the first rise in progesterone in the plasma to (1) sham-operation, (2) removal of the nonluteal ovary, (3) removal of the luteal ovary and (4) removal of the luteal ovary plus progesterone replacement (5 mg given three times 12 h apart, initiated at surgery). No effect of treatment on subsequent ovarian activity was observed. In Exp. 2, four of 14 lambs were assigned randomly to be hysterectomized before their first rise in progesterone. The remaining 10 lambs, (five each) were sham-operated or hysterectomized on the day of the first rise in progesterone. All hysterectomized lambs (N = 9) exhibited a rise in progesterone and maintained elevated concentrations of progesterone, whereas sham-operated lambs initiated estrous cycles. Oviducts and uteri collected from lambs hysterectomized on the day of the first rise in progesterone in Exp. 2 were flushed for presence of oocytes and none were found. Similarly, no retained oocytes were found in histological preparations of first luteal structures obtained from eight lambs ovariectomized in Exp. 1. Concentrations of luteinizing hormone (LH) and prolactin were determined in daily samples collected from 19 lambs in Exp. 1. Luteinizing hormone increased and became more variable as lambs matured, whereas prolactin decreased with no detectable change in variability. It is concluded that the transient luteal structure is not required for sexual maturation and that its lifespan is uterine dependent.

Animals↗
PubMed1983

Effects of ovarian secretions and dopamine on secretion of luteinizing hormone and prolactin in ewes.

In the present study, effects of dopamine (DA) and ovarian secretions on release of luteinizing hormone (LH) and prolactin (PRL) were examined using two methods of withdrawal of progesterone. Eight to 10 d after estrus, 36 ewes were assigned to one of six treatments: 1) lutectomy; 2) lutectomy and DA; 3) ovariectomy; 4) ovariectomy and DA; 5) ovariectomy and estradiol-17 beta or 6) ovariectomy, estradiol-17 beta and DA. Estradiol-17 beta was administered by Silastic implants inserted during surgery. Immediately after surgery, ewes were infused iv with DA (6.6 micrograms X kg-1 X min-1) or saline for 48 h. Infusion of DA did not affect secretion of LH after surgical removal of the corpus luteum. In lutectomized ewes, concentrations of LH in serum increased between 0 and 12 h from .5 to 3.3 ng/ml, declined between 12 and 16 h and then plateaued at 1.1 to 1.5 ng/ml. In contrast, concentrations of LH in ovariectomized ewes increased between 0 and 12 h and then remained at 3 to 5 ng/ml. Surges of LH occurred between 40 and 50 h postsurgery in eight of 12 lutectomized ewes, 11 of 12 ovariectomized ewes with implants of estradiol-17 beta and zero of 12 ovariectomized ewes. The magnitude of the surge of LH was higher in lutectomized ewes than in ovariectomized ewes with implants of estradiol-17 beta. Infusion of DA inhibited release of PRL, but there was no effect of method of progesterone withdrawal. Lutectomized ewes, but not ovariectomized ewes with implants of estradiol-17 beta, had a surge of PRL associated with the surge of LH.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Use of prostaglandin F2 alpha or gonadotropin releasing hormone in treating problem breeding cows.

Ten veterinarians diagnosed and treated 296 cows for reproductive irregularities on 28 dairy farms. Average interval from treatment with 25 mg of prostaglandin F2 alpha (137 cows) to estrus for cows with a corpus luteum (14.6 days) was reduced compared to saline (52 cows) (21.8 days), and a greater percentage (41.6 versus 17.3%) showed estrus within 6 days of treatment. Cows with a cystic corpus luteum (28) were detected in estrus at comparable intervals after prostaglandin F2 alpha or saline (21.8 versus 21.2 days), and similar proportions of cows were detected in estrus within 6 days of treatment (16.7 versus 10.0%). Intervals to estrus among cows with cystic follicles (40 cows) or anestrous cows with follicular ovaries (39 cows) did not differ after treatment with saline or 100 or 200 micrograms of gonadotropin releasing hormone. Within 25 days after treatment, 47.5% of cows with cystic ovaries and 64.1% of anestrous cows showed estrus. Number of cows pregnant after as many as three artificial inseminations of the number examined was 46%, whereas average number of conceptions per service was .32. The long interval from parturition to examination (112 days), the low rate of estrous response after treatment, and the long interval (1.6 estrous cycles) between estruses are consonant with inadequate estrous detection.

Anestrus↗
PubMed1982

The effects of timolol maleate and acetazolamide on the rate of aqueous formation in normal human subjects.

We used a double-masked, randomized, placebo-controlled study of the effect of acetazolamide alone and timolol maleate alone and of the two in combination on the rate of aqueous humor flow in 21 normal subjects. The rate of aqueous flow was measured by fluorophotometry over an eight-hour period. Timolol decreased the flow by 33%, acetazolamide by 27%, and the drug combination by 44%, compared to the placebo treated eye (P less than .01). Timolol produced a 26% decrease in intraocular pressure. Timolol decreased the intraocular pressure in the fellow eye by 16%, acetazolamide by 21%, and the two drugs together by 35% (P less than .01). Neither drug significantly affected the anterior chamber volume, the endothelium's permeability, or the estimated endothelial pump rate.

Acetazolamide↗