THE INFLUENCE OF EXOGENOUS GROWTH HORMONE ON ENDOCRINE STATUS AND THE OVULATORY RESPONSE TO PMSG IN PREPUBERTAL GILTS

1990 ◽  
Vol 70 (1) ◽  
pp. 309-312 ◽  
Author(s):  
R. N. KIRKWOOD ◽  
P. A. THACKER ◽  
R. S. KORCHINSKI ◽  
B. LAARVELD
Keyword(s):  
Growth Hormone ◽  
Key Words ◽  
Jugular Vein ◽  
Serum Concentrations ◽  
Blood Samples ◽  
Exogenous Growth ◽  
Endocrine Status ◽  
The Difference ◽  
To Receive ◽  
Surge Height

Twenty-three prepubertal Yorkshire × Landrace gilts were allocated to receive daily injections of either porcine growth hormone (pGH) or vehicle for 6 consecutive days. At the time of first pGH or buffer injection, all gilts received an injection of 500 IU PMSG. Blood samples were taken by jugular vein puncture at 0, 24 and 48 h then every 12 h until 96 h then every 8 h until 144 h. Samples were assayed for triiodothyronine (T3), insulin, glucose and LH. Treatment with pGH elevated (P < 0.01) serum concentrations of T3, insulin and glucose, and was associated with a reduced (P < 0.05) LH surge height. Fewer pGH-treated than vehicle-treated gilts ovulated (4/12 vs. 7/11), but the difference was not significant. Key words: Gilts, growth hormone, gonadotrophins, ovulation

THE INFLUENCE OF GROWTH HORMONE TREATMENT ON THYROID FUNCTION IN SWINE

1990 ◽  
Vol 70 (3) ◽  
pp. 991-995 ◽  
Author(s):  
R. N. KIRKWOOD ◽  
P. A. THACKER ◽  
B. LAARVELD
Keyword(s):  
Growth Hormone ◽  
Body Weight ◽  
Key Words ◽  
Growth Hormone Treatment ◽  
Sampling Period ◽  
Hormone Treatment ◽  
Serum Concentrations ◽  
Significant Treatment ◽  
Blood Samples ◽  
To Receive

Twelve castrated male pigs of Yorkshire and Landrace breeding were selected at 95.9 ± 1.6 kg body weight (BW) and allocated equally to receive daily injections of either porcine growth hormone (pGH) at 90 μg kg−1 BW or vehicle buffer for four consecutive days. Following the last pGH injection, the pigs were infused via indwelling vena caval cannulae with thyrotropin-releasing hormone (TRH) at 0.5 μg kg−1 BW. Blood samples were obtained at 10 and 0 min before TRH and thereafter at 10-min intervals for 90 min. Serum concentrations of thyroxine and thyrotropin were lower (P < 0.06 and P < 0.1, respectively) but those of triiodothyronine higher (P < 0.01) in pGH-treated pigs throughout the sampling period. There were no significant treatment-by-time interactions indicating that the thyroid response to TRH was not influenced by pGH treatment. Key words: Swine, thyroid, growth hormone, somatotropin

The influence of monensin and lasalocid on the breeding performance of ewes and the endocrine status of ewe lambs

1991 ◽  
Vol 71 (4) ◽  
pp. 1073-1077 ◽  
Author(s):  
R. N. Kirkwood ◽  
P. A. Thacker ◽  
R. S. Rorchinski ◽  
A. Gonzalez ◽  
B. Laarveld
Keyword(s):  
Key Words ◽  
Breeding Performance ◽  
Blood Samples ◽  
Ewe Lambs ◽  
Serum Lh ◽  
Treatment Experiment ◽  
Endocrine Status ◽  
To Receive ◽  
Estradiol 17Β ◽  
Surge Height

Two experiments were performed, in December and August, to determine the effects of dietary ionophores on the breeding performance of ewes and the endocrine status of ewe lambs. Experiment 1 employed 127 mixed-parity ewes fed diets containing 33 ppm monensin (M, n = 43), 45 ppm lasalocid (L, n = 43) or no additive (C, n = 41). Estrus was synchronized with progesterone sponges and the ewes were allowed to breed. The proportion of ewes conceiving at their first estrus was higher (P < 0.05) for control ewes than for L ewes (70.7 vs. 51.2%) M ewes being intermediate (53.5%). Litter size of ewes conceiving at first estrus was not affected by treatment. Experiment 2 employed 57 ewe lambs allocated in a 3 × 2 factorial arrangement to be fed rations containing 33 ppm M, 45 ppm L or no additive for 26 d and to receive, or not, an injection of 50 μg GnRH at 21 d. For lambs receiving GnRH, blood samples were taken every 15 min for 2 h from 30 min pre-injection. At 72 h after GnRH injection, all lambs received an injection of 50 μg estradiol-17β. Further blood samples were taken from all lambs at 4-h intervals for 48 h. Serum LH and FSH concentrations increased from pre-injection means of 1.6 ± 0.2 and 7.8 ± 1.2 ng mL−1 to 20.9 ± 1.9 and 13.4 ± 1.4 ng mL−1, respectively, by 15 min after GnRH injection. These responses were not affected by either ionophore. The estradiol-induced LH surge height was reduced (P < 0.01) in lambs that had received GnRH. These data indicate that at the dietary inclusion levels employed, ionophores may be contra-indicated in the breeding ration. Key words: Ionophores, ewes, reproduction

THE EFFECT OF EXOGENOUS GROWTH HORMONE ON THE ENDOCRINE STATUS AND THE OCCURRENCE OF ESTRUS IN GILTS

1989 ◽  
Vol 69 (4) ◽  
pp. 931-937 ◽  
Author(s):  
R. N. KIRKWOOD ◽  
P. A. THACKER ◽  
B. L. GUEDO ◽  
B. LAARVELD
Keyword(s):  
Adverse Effect ◽  
Growth Hormone ◽  
Estrous Cycle ◽  
Ovarian Function ◽  
Jugular Vein ◽  
Ovulation Rate ◽  
Estrous Cycles ◽  
Endocrine Status ◽  
To Receive

Fifty-six gilts of Yorkshire and Landrace breeding were selected at 86.8 ± 0.8 kg body weight (BW) and given an intramuscular (im) injection of 400 IU PMSG plus 200 IU hCG to stimulate ovulation. From 14 d after gonadotropic stimulation, gilts were exposed to a boar to detect a subsequent spontaneous estrus. At the onset of this first observed estrus, gilts were allocated to receive daily injections (i.m.) of growth hormone (pGH, 90 μg kg−1) from either 14 d (GH14, n = 21) or 17 d (GH17, n = 20) until 22 d after the onset of the first observed estrus. A third group of gilts served as controls (n = 15) and received vehicle buffer. Blood samples were obtained by jugular vein puncture at 3-d intervals from 14 to 29 d, inclusively. Gilts were slaughtered 30–32 d after the first observed estrus at which time their ovaries were recovered for the determination of ovulation rates. All control gilts and all but one GH17 gilt exhibited normal estrous cycles. However, of the 21 gilts assigned to GH14, only 9 (43%) had normal estrous cycles (P < 0.001). In gilts exhibiting a second estrus, there was no effect of pGH treatment on the duration of the estrous cycle (20.4, 20.9 and 20.5 d) or on ovulation rate (14.6, 13.9 and 13.5) for GH14, GH17 and controls, respectively. Serum assays revealed that pGH injections resulted in decreased serum concentrations of thyroxine (P < 0.01) but increased concentrations of triiodothyronine, insulin and glucose (P < 0.001). The present data confirm an adverse effect of pGH on ovarian function. However, the adverse effect is only evident when the pGH injection regime encompasses days 14–16 of the estrous cycle. Key words: Gilts, growth hormone, estrus, ovulation rate

THE INFLUENCE OF EXOGENOUS GROWTH HORMONE ON OVULATION RATE IN GILTS

1988 ◽  
Vol 68 (4) ◽  
pp. 1097-1103 ◽  
Author(s):  
R. N. KIRKWOOD ◽  
P. A. THACKER ◽  
A. D. GOONERATNE ◽  
B. L. GUEDO ◽  
B. LAARVELD
Keyword(s):  
Growth Hormone ◽  
Crude Protein ◽  
Ovulation Rate ◽  
Daily Injection ◽  
Corpora Lutea ◽  
Blood Samples ◽  
High Incidence ◽  
Exogenous Growth ◽  
Ad Libitum

A total of 32 prepubertal gilts of Yorkshire and Landrace breeding were selected at 138 d and fed ad libitum a 16.2% crude protein diet formulated to provide 13.1 MJ DE kg−1. From selection until the end of second estrus, the gilts were exposed to a boar for 30 min d−1 to facilitate the detection of pubertal and second estrous periods. From 14 d after puberty, the gilts received daily injections of either porcine growth hormone at 90 μg kg−1 body weight (GH; n = 20) or vehicle (CT; n = 12) until 24 h after the onset of second estrus and were then killed 9 d later to determine ovulation rate. Gilts not displaying a second estrus by 24 day after puberty were considered anestrus and the injection regime was halted. Anestrous gilts were killed 30–32 d after puberty and their ovaries examined for the presence of corpora albicantia and the absence of corpora lutea. Blood samples were obtained from all gilts at 14, 17, and 20 d after puberty. There was no treatment effect on the duration of the estrous cycle (20.8 vs. 21.3 d for GH and CT, respectively), but while all CT gilts cycled normally, only 55% of the GH gilts had a second estrus (P < 0.01). In those gilts having a second estrus, the daily injection of growth hormone increased ovulation rate (14.3 vs. 12.4 for GH and CT respectively; P < 0.03). Serum type 1 insulin-like growth factor (IGF-1) concentrations were higher (P < 0.001) in GH than in CT gilts, but there was no difference between cycling and anestrous GH gilts. We suggest that the effect of growth hormone on ovulation rate was mediated by increased secretion of IGF-1. The etiology of the high incidence of anestrus is, however, not known. Key words: Gilts, growth hormone, ovulation rate

The influence of dietary monensin and salinomycin on growth and endocrine status of gilts

1992 ◽  
Vol 72 (2) ◽  
pp. 427-429 ◽  
Author(s):  
T. A. Van Lunen ◽  
R. N. Kirkwood ◽  
P. A. Thacker
Keyword(s):  
Growth Hormone ◽  
Body Weight ◽  
Key Words ◽  
Crude Protein ◽  
Protein Diet ◽  
Serum Growth Hormone ◽  
Endocrine Status ◽  
Effect Of Treatment

Seventy-two gilts were fed a 16% crude protein diet supplemented with monensin, salinomycin or not supplemented. There was no effect of treatment on gilt growth between 30 and 100 kg body weight. Monensin-fed gilts tended to have increased, while salinomycin-fed gilts had decreased (P < 0.01), serum growth hormone concentrations. Salinomycin-fed gilts were older and heavier at puberty (P < 0.05). Key words: Monensin, salinomycin, gilts, growth, reproduction

EFFECT OF STAGE OF LACTATION AND OF DAILY INJECTIONS OF GRF AND TRF ON SERUM CORTISOL IN LACTATING SOWS

1988 ◽  
Vol 68 (3) ◽  
pp. 689-697 ◽  
Author(s):  
S. ROBERT ◽  
A.-M. B. DE PASSILLÉ ◽  
N. ST-PIERRE ◽  
G. PELLETIER ◽  
P. DUBREUIL ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Key Words ◽  
Serum Cortisol ◽  
Cortisol Secretion ◽  
Serum Concentrations ◽  
Late Afternoon ◽  
Stage Of Lactation ◽  
Basal Serum ◽  
Lactating Sows ◽  
Key Words Cortisol

Two experiments were conducted with 51 primiparous sows to determine the effects of stage of lactation and treatment with growth hormone-releasing factor (GRF) and thyrotropin-releasing factor (TRF) on serum cortisol concentrations and pulse profiles. Animals were injected with either saline, GRF (20 μg kg−1 in both experiments), TRF (1 μg kg−1 and 9 μg kg−1 in exps. 1 and 2, respectively) or GRF-TRF (administered in combination at the levels mentioned above). Peptides were given subcutaneously twice daily between days 5 and 25 postpartum. In exp. 1, mean cortisol levels were higher on day 5 than on subsequent sampling days due to higher peak amplitudes. This result is discussed with respect to stress. Mean serum cortisol concentrations did not vary significantly between days 5, 15 and 25 of lactation in exp. 2. No evidence of a morning peak and late afternoon low was observed in cortisol secretion of sows during lactation. Finally, none of the hypothalamic factor treatments altered the basal serum concentrations or the peak amplitudes of cortisol. However, in exp. 2, the frequency of cortisol peaks was lower for the GRF- and TRF-treated sows than for the control and GRF-TRF sows. Key words: Cortisol, GRF, TRF, lactation, sows

THE INFLUENCE OF GILT AGE ON THE ENDOCRINE AND OVULATORY RESPONSE TO DIFFERENT DOSES OF ESTRADIOL BENZOATE

1988 ◽  
Vol 68 (3) ◽  
pp. 979-982 ◽  
Author(s):  
R. N. KIRKWOOD ◽  
F. X. AHERNE
Keyword(s):  
Body Weight ◽  
Luteinizing Hormone ◽  
Key Words ◽  
Jugular Vein ◽  
Estradiol Benzoate ◽  
Blood Samples ◽  
Estrous Cyclicity ◽  
The Mean ◽  
Different Doses ◽  
Phasic Release

Fifty-five prepubertal Yorkshire × Landrace gilts were randomly assigned to one of six treatments involving the injection (i.m.) of estradiol benzoate (EB) at either 10 or 20 μg kg−1 body weight at gilt ages of 130, 150 or 170 d. Blood samples were taken by jugular vein puncture at 0, 24, and 36 h, and then at 6-h intervals until 84 h, after injection and assayed for plasma luteinizing hormone (LH) concentrations. The mean magnitude of the EB-induced LH peak was 6.1 ± 0.2 ng mL−1, and was not affected by treatment. Fifty-six percent of gilts ovulated in response to EB injection, and 34% had a subsequent ovulation. The initial ovulation rate was unaffected by EB dose, but was higher (P < 0.05) in 170 d (9.9 ± 1.0) compared to younger gilts (4.2 ± 1.1 and 5.5 ± 1.1 for 130-dand 150-d gilts, respectively). Subsequent ovulation rates were unaffected by treatment. It is concluded that EB treatment will usually induce a phasic release of LH from prepubertal gilts, but this release is not necessarily accompanied by normal estrous cyclicity. Key words: Estradiol, gilts, ovulation

EFFECT OF EXOGENOUS GROWTH HORMONE DURING THE FOLLICULAR PHASE ON hCG BINDING BY PORCINE LUTEAL TISSUE

1990 ◽  
Vol 70 (2) ◽  
pp. 719-721 ◽  
Author(s):  
R. N. KIRKWOOD ◽  
P. A. THACKER ◽  
B. L. GUEDO ◽  
B. LAARVELD
Keyword(s):  
Growth Hormone ◽  
Key Words ◽  
Ovarian Function ◽  
Binding Capacity ◽  
Follicular Phase ◽  
Corpora Lutea ◽  
Exogenous Growth ◽  
Luteal Tissue

From 14 d after puberty, 37 Yorkshire Landrace gilts received nine daily injections of porcine growth hormone (GH) or vehicle. Gilts were killed 10 d after the onset of their second estrus and their ovaries recovered. Treatment with GH resulted in an increase (P < 0.05) in the hCG binding capacity of the corpora lutea (0.17 vs. 0.11 nmol L−1 mg−1 protein). These data provide a possible mechanism whereby GH may influence ovarian function. Key words: Gilts, hCG binding, growth hormone

scholarly journals Central and peripheral administration of kisspeptin activates gonadotropin but not somatotropin secretion in prepubertal gilts

Reproduction ◽  
2008 ◽  
Vol 135 (6) ◽  
pp. 879-887 ◽  
Author(s):  
Clay A Lents ◽  
Neely L Heidorn ◽  
C Richard Barb ◽  
J Joe Ford
Keyword(s):  
Hormone Secretion ◽  
Domestic Animals ◽  
Laboratory Animals ◽  
Dependent Manner ◽  
Serum Concentrations ◽  
Blood Samples ◽  
Somatotropic Hormone ◽  
Gh Secretion ◽  
To Receive ◽  
Dose Dependent

It is well established that kisspeptin signaling is necessary for the onset of puberty in laboratory animals. However, the role that kisspeptin may have in regulating puberty in large domestic animals is unknown. We tested the hypothesis that either central or peripheral infusion of kisspeptin would stimulate gonadotropin and GH secretion in prepubertal gilts. In experiment 1, prepubertal gilts were fitted with i.c.v. cannula and indwelling jugular catheters. Animals were randomly assigned to receive 0, 10, or 100 μg kisspeptin in saline. In experiment 2, prepubertal gilts, fitted with indwelling jugular catheters, randomly received 0, 1, 2.5, or 5 mg kisspeptin in saline intravenously. Serial blood samples were collected every 15 min for 3 h before and 5 h after infusions, and serum concentrations of LH, FSH, and GH were determined. Mean concentrations of LH and FSH remained at basal levels for control animals but were increased (P<0.001) for animals receiving i.c.v. infusion of kisspeptin. Area under the LH and FSH curves following i.c.v. infusion of kisspeptin increased (P<0.001) in a dose-dependent manner. Concentrations of GH were unaffected by i.c.v. treatment. Peripheral administration of kisspeptin increased (P<0.05) serum concentrations of LH but not FSH or GH. Thus, kisspeptin can activate gonadotropic but not somatotropic hormone secretion in prepubertal gilts. The present data support the concept that kisspeptin plays a role in the mechanism involved in initiating puberty in swine.

THE INFLUENCE OF EXOGENOUS GROWTH HORMONE ON OVULATION RATE IN GILTS FED DIETS WITH DIFFERENT ENERGY AND PROTEIN CONTENTS

1989 ◽  
Vol 69 (1) ◽  
pp. 265-268 ◽  
Author(s):  
R. N. KIRKWOOD ◽  
P. A. THACKER ◽  
B. LAARVELD
Keyword(s):  
Growth Hormone ◽  
Key Words ◽  
Feed Intake ◽  
Dietary Treatment ◽  
High Energy ◽  
Ovulation Rate ◽  
Induced Ovulation ◽  
Exogenous Growth

Following pregnant mare's serum gonadotrophin (PMSG) induced ovulation, 61 Yorkshire × Landrace gilts were allocated to be fed either a control or a high-energy diet for 30 d. From 14 d, gilts on each dietary treatment received nine daily injections of porcine growth hormone or vehicle. Growth hormone depressed feed intake by 30% (P < 0.001), but did not influence ovulation rate. No influence of diet or growth hormone on the incidence of a subsequent ovulation was apparent. Key words: Gilts, diet, growth hormone, ovulation rate

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