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Biomedical subjects

B N Day

Publications and source records attributed to B N Day.

At least 127 records · Page 7Linked to original sources
PubMed1986

Ovarian compensatory hypertrophy following unilateral ovariectomy in the suckled sow.

The effects of unilateral ovariectomy on ovarian compensatory hypertrophy (OCH), endocrine profiles and the pituitary response to gonadotropin releasing hormone (GnRH) were studied in 46 multiparous suckled sows. On d 20 of lactation (d 0 of experiment), sows were subjected to sham ovariectomy (Sham; n = 23) or unilateral ovariectomy (ULO; n = 23). On d 1 (n = 16), 2 (n = 15) or 8 (n = 15) following initial surgery the remaining ovaries in both Sham and ULO sows were removed. Immediately following removal of the remaining ovaries, GnRH (10 micrograms) was administered to each sow. Peripheral blood samples were taken every 10 min for 80 min beginning 20 min prior to GnRH administration. No difference in ovarian weight was observed between ULO and Sham sows until d 8, when ovarian weight was greater (P less than .05) for the remaining ovary from ULO sows (3.96 +/- .21 vs 5.91 +/- .39 g). Ovarian follicular fluid weights from ULO sows were greater (P less than .05) than Sham sows on both d 2 and 8. On d 1, plasma concentrations of follicle stimulating hormone (FSH) were greater (P less than .05) in ULO sows than in Sham sows (2.9 +/- .2 vs 2.1 +/- .1 ng/ml). Plasma FSH concentrations, however, did not differ between Sham and ULO sows on either d 2 or 8. Ovarian venous concentrations of estradiol-17 beta were also greater (P less than .05) in ULO sows compared with Sham sows on d 2 but not d 8.

Animals↗
PubMed1985

Parturition control in sows with a prostaglandin analogue (alfaprostol).

The objective of this study was to determine the dose of alfaprostol (18, 19, 20-trinor-17-cyclohexyl-13, 14 didehydro-PGF(2)alpha-methylester) and the day of administration most effective in inducing sows to farrow during normal working hours (0700 to 1700). One-hundred forty multiparous crossbred sows, taken from a herd whose mean gestation length was 114.3 days, were assigned to one of five treatment groups: 1) control vehicle-propylene glycol, 2) 0.5 mg alfaprostol (AP). 3) 1 mg AP, 4) 2 mg AP and 5) 3 mg AP. Sows received an intramuscular injection of AP between 0800 and 0830 on either day 111, 112 or 113 of gestation. Parameters studied included interval from injection to birth of first pig, farrowing interval, total number of pigs born, number born alive, average birth weight, percent stillborn, interval from weaning to next estrus and number born alive next litter. The mean intervals from injection to the birth of the first pig were 55.2 +/- 7.1; 41.1 +/- 5.1; 29.6 +/- 4.0; 24.3 +/- 1.1; 24.8 +/- 0.9 h for groups 1, 2, 3, 4 and 5, respectively (P<0.05). The percentage of sows that farrowed during normal working hours (23 to 33 h after injection) for groups 1, 2, 3, 4 and 5 were 15, 53, 60, 77 and 70%, respectively. Average birth weights (kg) for treatment groups 1, 2, 3, 4 and 5 were 1.54 +/- 0.05; 1.65 +/- 0.05; 1.59 +/- 0.05; 1.54 +/- 0.05 and 1.42 +/- 0.05, respectively (P<0.05). Mean differences in total number of pigs born and number born alive were also statistically significant (P<0.05) but stillbirth rate was not different (P>0.05) among treatment groups. These results indicate that a single injection of 1, 2 or 3 mg of alfaprostol will successfully induce parturition the following day in a majority of the treated sows.

Journal Article↗
PubMed1985

Effect of follicular fluid treatment on follicle-stimulating hormone, luteinizing hormone and compensatory ovarian hypertrophy in prepuberal gilts.

Prepuberal 130-day-old gilts were treated with 10 ml of charcoal-stripped porcine serum (PS), whole porcine follicular fluid (WpFF) or charcoal-stripped pFF (CpFF) twice daily beginning the day before and continuing 8 days after unilateral ovariectomy (ULO). Follicle-stimulating hormone (FSH) declined for the first 14 h after ULO in WpFF and CpFF gilts and then by 24 h returned to values observed at or before ULO, whereas FSH was increased nearly twofold at 14 h in PS gilts. At 8 days after ULO the remaining ovaries from PS-treated gilts were heavier than ovaries from follicular fluid-treated gilts. In a second experiment, ovariectomized 130-day-old gilts were assigned to either a group infused with PS, a group infused with 5 ml CpFF, or a group infused with 10 ml Cpff at 18 and 2 h before a gonadotropin-releasing hormone (GnRH) challenge. Porcine follicular fluid had no effect on luteinizing hormone (LH) response to GnRH, depressed the FSH response to a 10-micrograms challenge of GnRH, but had no effect on FSH response to a 50-micrograms challenge of GnRH. In a third study, gilts were subjected to sham ovariectomy (Sham) or ULO at 130 days of age. GnRH (10 micrograms) was given on Days 1, 2 or 8 after surgery. The response to GnRH in ULO versus Sham gilts did not differ for FSH or LH on any day.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1984

Effect of unilateral ovariectomy on compensatory ovarian hypertrophy, peripheral concentrations of follicle-stimulating hormone and luteinizing hormone, and ovarian venous concentrations of estradiol-17 beta in prepuberal gilts.

A study was designed to characterize the compensatory ovarian response to unilateral ovariectomy (ULO) in prepuberal gilts and to investigate further the mechanisms involved in compensatory ovarian hypertrophy (COH). Forty-eight crossbred gilts were sham ovariectomized (Sham) or unilaterally ovariectomized at 130 days of age (Day 0). Remaining ovaries in ULO gilts were removed and Sham gilts were bilaterally ovariectomized 2, 4 or 8 days later. A peripheral blood sample was taken before surgery and ovarian venous blood samples were taken before removal of each ovary. Serum estradiol-17 beta (E2) concentrations were determined. Mean wet and dry ovarian weights per ovary on Day 2 for ULO and Sham gilts were 3.4 versus 2.8 and 0.26 versus 0.24 g, respectively. Those weights on Days 4 and 8 were greater (P less than 0.01) for ULO than Sham gilts. Follicular fluid weight per ovary was greater (P less than 0.05) for ULO than Sham gilts on Days 2, 4 and 8. Ovarian venous E2 concentrations were greater (P less than 0.01) for ULO than for Sham gilts on Days 2 and 4 but were similar on Day 8. In a second experiment, 42 prepuberal gilts 130 days of-age were subjected to Sham (n = 18), ULO (n = 18) or bilateral ovariectomy (BLO; n = 6) to evaluate follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion immediately after surgical treatment. Release of FSH within the first 24 h was greater for BLO than ULO and for ULO than Sham gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1982

Bilateral luteal maintenance in unilaterally pregnant pigs with infusions of embryonic extracts.

Thirty unilaterally pregnant gilts with bilateral corpora lutea received infusions three times daily into a surgically isolated, nonpregnant uterine horn from d 12 through d 19 after mating. The infusions consisted of either saline alone or embryonic extracts in saline which were either untreated, heat-treated or charcoal-absorbed. The extracts were from porcine embryos, embryonic membranes and fluids between d 16 and 25 of pregnancy. While only 20% of the gilts infused with saline alone and none of those infused with charcoal-absorbed embryonic extracts maintained pregnancy to d 19, 100 and 83% of the gilts infused with untreated and heal-treated embryonic extracts, respectively, were pregnant on d 19. Similar treatment effects were observed for the incidence of bilateral luteal maintenance. No gilts receiving infusions of either saline or charcoal-absorbed embryonic extracts exhibited bilateral luteal maintenance. However, 67% of the gilts infused with untreated embryonic extracts and 67% of those infused with heated extracts had bilateral luteal maintenance on d 19. Additionally, the weights and progesterone concentrations of corpora lutea adjacent to the infused uterine horns were not different (P less than .05) from those of the corpora lutea adjacent the to pregnant uterine horns in gilts with bilateral luteal maintenance.

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PubMed1982

Local effects of PGF2 alpha and embryonic extracts on luteal function in swine.

Individual corpora lutea (CL) from 10 gilts were assigned to seven treatment groups. Corpora lutea assigned to group 1 were unimplanted, while those in groups 2 through 7 were given implants congealed with saline, prostaglandin F2 alpha (PGF2 alpha) vehicle, PGF2 alpha, PGF2 alpha and untreated embryonic extracts, PGF2 alpha and heated embryonic extracts or PGF2 alpha and charcoal-adsorbed embryonic extracts, respectively. Individual CL implanted with PGF2 alpha alone had a lower (P less than .05) mean weight and progesterone concentration than CL in all other treatment groups except those treated with PGF2 alpha and charcoal-adsorbed embryonic extracts. Untreated and heat-treated embryonic extracts prevented the reduction in luteal weight and progesterone concentration induced by PGF2 alpha treatment.

Animals↗
PubMed1982

Changes in plasma hormone concentrations associated with the onset of puberty in the gilt.

Hormonal changes during the follicular phase of gilts exhibiting their first estrus were examined in response to either relocation and boar exposure or treatment with pregnant mare serum gonadotropin (PMSG). In the first experiment, blood was collected from nine gilts from 6 d before to 6 d after the onset of first estrus. Mean estradiol-17 beta (E2 beta) concentrations increased from d -6 to a peak on d -2 of 20 pg/ml (d 0 = of estrus) and then declined gradually over the next 6 d until basal levels (2.4 pg/ml) were reached. Mean concentrations of luteinizing hormone (LH) fluctuated between .5 to 1 ng/ml before d 1.5 and after d 1.5, with the ovulatory surge occurring on either d -1 or d 0 and averaging 6.2 ng/ml. Progesterone (P) concentrations were less than .3 ng/ml until formation of corpora lutea, while concentrations of glucocorticoids (CORT) ranged from 7.4 to 24.5 ng/ml. In Exp. 2, blood was collected every 6 h from d -2 to d 14 from eight gilts that were exposed to boars on d 0. Four of the gilts exhibited estrus and had a hormonal profile similar to that of gilts in Exp. 1. Concentrations of E2 beta were elevated in two gilts after exposure to a boar, but concentrations of LH were not altered. The remaining two gilts had basal concentrations of E2 beta and LH throughout the blood sampling period. In Exp. 3, blood was sampled from five gilts twice daily for 8 d following the administration of 1,000 IU PMSG. Estrus was exhibited by all gilts on the fifth day after PMSG. Circulating concentrations of total estrogens peaked on -1 while concentrations of LH peaked on d 0. Concentrations of P were low until after estrus and CORT levels displayed a diurnal pattern throughout. The results indicate that the hormonal profiles during the pubertal follicular phase of gilts induced by relocation and boar exposure or PMSG are similar. Furthermore, no changes were observed in P concentrations immediately before or during the pubertal follicular phase, suggesting that progesterone priming may not be prerequisite to puberty in gilts.

Animals↗
PubMed1981

GnRH induced LH release in suckled beef cows. II. The effects of exogenous corticoids and estradiol benzoate on luteinizing hormone release by GnRH.

In Experiment 1, 24 suckled beef cows were assigned to 4 treatment groups (6 cows/group). Group I cows calved spontaneously. Parturition was induced in Groups 2, 3 and 4 with 20 mg dexamethasone (DEX) 8 to 12 days prior to expected calving date. Additionally, cows in Groups 3 and 4 received 8 mg triamcinalone acetonide (TA) 6 days prior to DEX treatment. Animals in Group 4 also received 10 mg estradiol benzoate (EB) with TA, and on alternate days until DEX, when 20 mg EB was given. Gonadotropin releasing hormone (GnRH, 100 mug) was given intramuscular (IM) to all cows on days 2 or 3 postpartum. Plasma LH increased (P< .05) following GnRH treatment in Groups 2, 3 and 4, but not in Group 1. LH release (area under the curve) following GnRH was greater (P< .05) for cows in Group 4 compared to cows in Groups 1, 2 or 3, and differences in LH release between Groups 1, 2 or 3 were not significant. In Experiment II, 36 mature Hereford cows were assigned to a 2 x 3 factorial experiment (6 cows/group). Groups 1 and 2, 3 and 5, and 4 and 6 received 0, 100, or 200 mug GnRH (IM) at 78 hr postpartum, respectively. In addition, cows in Groups 2, 5 and 6 received 5 mg EB at 36 hr postpartum. Plasma LH concentrations were not different (P <.05) among groups from 36 to 78 hr postpartum. A surge of LH in response to EB treatment was not detected at 54 to 62 hr (18 to 26 hr post EB), indicating a lack of response by the positive feedback mechanism at this early time postpartum. Mean plasma LH concentrations were elevated 78 to 82 hr postpartum for Groups 3 through 6. Treatment with EB at 36 hr caused a significantly greater (P< .05) response to GnRH with 200 mug of GnRH releasing more LH than 100 mug of GnRH.

Journal Article↗
PubMed1981

The effect of luteinizing hormone, human chorionic gonadotropin and adrenocorticotropic hormone on puberty in gilts reared in confinement.

Three trials were conducted to determine the effect of human chorionic gonadotropin (HCG), luteinizing hormone (LH) and adrenocorticotrophic hormone (ACTH) on the incidence of estrus in gilts which were reared in confinement, relocated and exposed to a boar. In trial 1, 33 gilts were given saline or 250 IU HCG at an average age of 191 days and then relocated and observed for estrus twice daily for 10 days. Treatment with HCG did not increase the proportion of gilts that exhibited estrus. In trial 2, 42 gilts were relocated at an average age of 200 days. The gilts were assigned to three treatment groups and injected with saline, 68 microg LH or 1 mg LH. After 10 days of estrous detection, a laparoscopic examination of the ovaries was conducted on all gilts failing to exhibit estrus. In groups 1 to 3, the proportions of gilts exhibiting estrus or ovulating during the 10 days after treatment were 13 of 21, 6 of 10, and 5 of 11, respectively. In trial 3, 12 gilts were relocated to pasture lots, given saline or 80 IU ACTH twice daily for 2 days and checked for estrus for 14 days. The proportions of gilts that exhibited estrus after the administration of saline or ACTH were 4 of 6 and 6 of 6, respectively. The results indicate that the incidence of estrus in gilts reared in confinement, relocated and exposed to a boar was not affected by pre-treatment with exogenous HCG, LH or ACTH.

Journal Article↗
PubMed1981

GnRH induced LH release in suckled beef cows. 1. The effects of days postpartum and estradiol-17beta concentrations on the release of LH following administration of GnRH.

Twenty suckled CharloixxHereford beef cows (5 cows/group) were assigned at random to receive 100 microg GnRH (IM) at either 2 to 3, 7 to 8, 15 to 16, or 31 to 32 days postpartum, Groups 1 through 4, respectively. Blood samples for hormone determinations were collected at time 0 (pre-GnRH), every half hr for 3 hr, and at 4.0 hr and 6.0 hr post-GnRH. Mean plasma LH, estradiol-17beta, or progesterone concentrations were not different among groups prior to GnRH. Plasma LH increased (P<.05) following GnRH in Groups 2, 3 and 4, but not in Group 1. Peak GnRH induced LH release was greater (P<.05) in Groups 3 and 4 than in Groups 1 or 2. Correlation coefficients between days postpartum and peak LH release (r=.72), and estradiol-17beta concentrations and time of LH peak (r=-.42) were significant (P<.05). These data indicate that LH release in response to GnRH, in suckled beef cows is not fully restored until 15 to 16 days postpartum.

Journal Article↗
PubMed1981

Estrus and ovulation in gilts fed a synthetic progestogen.

A synthetic progestogen, allyl trenbolone (AT), was fed to sexually mature gilts to determine the effective doses for the control of estrus and ovulation. Gilts were assigned to a control group and 5 treatment groups receiving 10.0, 12.5, 15.0, 17.5 or 20.0 mg of AT mixed in .45 kg of feed/head/day for 18 consecutive days. Ovarian morphology was determined by laparotomy following estrus or at 10 days post-treatment. AT suppressed estrus in all gilts during treatment. Estrus was effectively synchronized in treated gilts. The average interval from withdrawal of progestogen treatment to estrus was 4.5 days for 48 of 50 treated gilts that were in estrus within 10 days after treatment. The average ovulation rate in treated gilts was similar to control gilts. No detrimental side effects, due to treatment, were observed with the possible exception of a slight increase in the incidence of cystic follicles.

Journal Article↗
PubMed1981

Plasma prolactin concentration in gilts reared in confinement.

Plasma prolactin concentrations were determined in confinement-reared gilts, which were subsequently exposed to boars and/or relocated to pasture lots. At an average age of 181 days, an indwelling vascular cannula was surgically implanted, and 28 gilts were assigned randomly to either control (remained in confinement) or treatment (relocated to pasture) groups. Nine of the gilts in each group were exposed to a mature boar twice daily. Furthermore, the experiment was divided between April (n=17 gilts) and September (11 gilts). Blood samples were drawn at the time of surgical implantation and twice daily thereafter. Plasma concentrations of prolactin were quantified by validated radio-immunoassay procedures. Samples which were collected at surgery had significantly more prolactin than post-surgical samples in 25 of 28 gilts. The overall average for the post-surgical concentration of prolactin was 2.7 ng/ml, and there was no effect of continued confinement versus relocation to pasture lots. There was a tendency for boar exposure to reduce prolactin levels in relocated gilts but not in control gilts. There was also a tendency for plasma prolactin to be greater in September than in April, especially in control gilts. Overall these results indicate that plasma prolactin levels do not reflect the delay of puberty in confinement-reared gilts or the induction of puberty caused by relocation to pasture lots.

Journal Article↗
PubMed1981

Ovarian activity and hormonal patterns in gilts fed allyl trenbolone.

A study was conducted to establish the profile of reproductive hormones and the degree of ovarian activity in gilts fed either 2.5 or 15.0 mg of allyl trenbolone (AT) daily. Progesterone levels following regression of corpora lutea remained low (less than 1 ng/Ml) during progestin treatment. In gilts given 2.5 mg AT, plasma estradiol (E2) levels fluctuated between 7 and 13 pg/ml during treatment and began to decrease by day 2 after withdrawal of AT. Gilts given 15 mg of AT had lower (P less than .01) plasma concentrations of E2 (2.5 pg/ml) during treatment; concentrations began to increase the day after withdrawal of AT, reaching a maximum of 13.1 pg/Ml in 3.5 to 4.0 days. Luteinizing hormone (LH) levels were low (less than 1.5 ng/ml) during AT treatment. Daily feeding of AT prevented estrus in all gilts. A preovulatory surge of LH (4 ng/ml) was observed on the first day of the first post-treatment estrus. Gilts given 2.5 mg of AT daily had more (P less than .01) follicles of ovulatory size during treatment and a higher frequency of cystic follicles after withdrawal than gilts given 15 mg of AT daily. Estrus was effectively synchronized in gilts given 15 mg of AT daily, whereas the feeding of 2.5 mg AT daily resulted in an increased incidence of anestrus.

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PubMed1980

The effects of triamcinolone acetonide on plasma glucocorticoid levels and occurrence of estrus in gilts.

Three experiments were conducted to examine the effect of adrenal corticoids on occurrence of estrus in gilts. In the first experiment, 10 mg of triamcinolone acetonide (TA), a synthetic glucocorticoid, were given to four ovariectomized and five diestrous gilts. Plasma glucocorticoid concentration declined to non-detectable levels within 5 hr of TA administration and remained at this level for 4 days in diestrous gilts and for 6 days in ovariectomized gilts. The second experiment examined the relationship between glucocorticoids and the expression of estrus in thirty-eight ovariectomized gilts. Seven of nine control gilts given .4 mg estradiol benzoate (EB) and three of four gilts given 10 mg TA 2 days before administration of .4 mg EB exhibited estrus. However, only one of four gilts displayed estrus when 10 mg TA were given simultaneously with EB, and none of seven gilts showed estrus after receiving 10 mg TA on days -7, -4, 0 and 4 (day 0 = the day of EB administration). The third experiment was conducted to determine the effect of TA on the expression of first estrus following relocation and exposure to a boar of gilts reared in confinement. Forty-three gilts were randomly assigned to a treatment or control group. Gilts in the treatment group were given 10 mg TA, and gilts in the control group received saline on days -3, 0, 4 and 8 (day 0 = the day of relocation and initial exposure to a boar). Gilts not exhibiting behavioral estrus by day 10 were given 80 IU ACTH. On day 20, all gilts failing to exhibit estrus were subjected to a laparoscopic examination of the reproductive tract and ovaries. Within 20 days after relocation and exposure to a boar, 15 of 21 control gilts and six of 22 treated gilts displayed first estrus (P < .01). However, ovarian stimulation had occurred in 10 treated gilts prior to laparoscopic examination. Seven of these gilts had corpora lutea present on the ovaries, two had cystic follicles and one had mature follicles. Therefore, treatment with TA did not alter the proportion of gilts demonstrating ovarian stimulation following relocation and exposure to a boar but significantly reduced the proportion of gilts exhibiting behavioral estrus.

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PubMed1980

The response of gilts reared in confinement to exogenous gonadotropin and estradiol benzoate.

To examine the effect of housing on the ovarian response to exogenous gonadotropins, 51 crossbred gilts were reared in confinement and assigned to a control or a treatment group at an average age of 212 days. Gilts in the control group were maintained in confinement and those in the treatment group were relocated to pasture lots. All gilts were fed a synthetic progestin for at least 19 days, given 1,000 IU pregnant mare serum gonadotropin (PMSG), checked for estrus and then laparotomized 1 to 5 days after estrus for examination of ovarian morphology. After withdrawal of the synthetic progestin and administration of PMSG, 24 of 26 treated gilts and 24 of 25 control gilts exhibited estrus. Single injections of 1,000 IU PMSG resulted in similar numbers of induced follicles and (or) corpora lutea in teated and control gilts. In the second experiment, 43 gilts reared in confinement were assigned to a control or treatment group at an average age of 180 days. Gilts in the control group were maintained in confinement, while gilts in the treatment group were relocated to pasture lots. All gilts were bilaterally ovariectomized, given .25 mg estradiol benzoate and checked twice daily for estrus. The proportion of gilts exhibiting estrus in the control and treatmet groups was 7 of 22 and 15 of 21, respectively (P < .01). The interval from injection of estradiol benzoate to the first day of estrus did not differ significantly between groups. The results indicate that housing in confinement does not affect the ovarian response of gilts to exogenous gonadotropin but that it may reduce the ability of gilts to respond to marginal levels of exogenous estrogen.

Animals↗