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PubMed1993

Postnatal development of uncoupling protein, uncoupling protein mRNA, and GLUT4 in adipose tissues of goats.

Adipose tissues have been characterized in newborn goats on the basis of the presence of the 32,000-M(r) mitochondrial uncoupling protein (UCP) diagnostic of brown fat, and early postnatal developmental changes have been determined. Both internal (perirenal, pericardial, and omental) and subcutaneous (hindlimb and neck regions) adipose tissues in newborn goats contained UCP and are therefore brown fat. The insulin-sensitive glucose transporter, GLUT4, was also present in adipose tissues of newborn goats, implying a potential for insulin-stimulated glucose uptake at birth. UCP was still evident in the perirenal fat of goats at 3 wk of age, but the mitochondrial concentration was only 4%, and the amount per cell a mere 0.2%, of that in the newborn. UCP was not detectable, however, in either the omental or subcutaneous adipose tissue at 3 wk of age and had disappeared from the subcutaneous fat before 2 wk. In contrast to UCP, GLUT4 remained throughout the initial 3 wk of postnatal life. The mRNA for UCP was detected in perirenal adipose tissue of newborn goats, indicating that the gene coding for the protein is being expressed at around birth. UCP mRNA was not, however, detectable in the other fat depots; nor was it evident in the perirenal adipose tissue at > or = 2.5 days of age. It is concluded that the adipose tissues of newborn goats (both internal and subcutaneous) represent brown fat and that there is a rapid transition toward white fat over the first weeks of life. This transition occurs at different rates in different depots but is not markedly faster in goats than in other ruminants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1981

Effect of peripheral chemoreceptor denervation on acclimatization of goats during hypoxia.

The purpose of this study was to determine the effect of peripheral chemoreceptor denervation on ventilatory acclimatization of goats during chronic hypoxia. After 1 h of stimulated altitude (PB 450 Torr), arterial O2 tension (PaO2) in seven normal goats averaged 42 Torr, and arterial CO2 tension (PaCO2) was 1.3 Torr below control (P less than 0.001). In these goats nearly 66% of the increase in alveolar ventilation (VA) associated with acclimatization occurred between 1.5 and 4 h of hypoxia. Acclimatization was complete by the 3rd day of hypoxia, and it caused 1) a 23% increase in VA/CO2 output (P less than 0.001); 2) a 5-Torr increase in PaO2 (P less than 0.001); and 3) a 6.5-Torr decrease in PaCO2 (P less than 0.001). Denervation of the carotid chemoreceptors in seven goats caused hypoventilation during eupnea at sea level (PaCO2 change from control +7 Torr, P less than 0.001). Denervation also attenuated but did not eliminate peripheral chemoreceptor responsiveness. No additional changes were observed following attempted denervation of the aortic chemoreceptors. After 1 h of simulated altitude (PB 530 Torr), PaO2 in the denervated goats averaged 46 Torr, and PaCO2 was increased 1.1 Torr above control (P less than 0.001). In these goats VA did not change significantly during the subsequent 3 days of hypoxia. Accordingly, we conclude that the peripheral chemoreceptors are essential for ventilatory acclimatization of goats during chronic hypoxia.

Acclimatization↗

PubMed1991

Effect of cardiac denervation on cardiorespiratory responses to exercise in goats.

The purpose of this study was to determine whether intact cardiac innervation and a normal cardiovascular (CV) response are required for a normal ventilatory (VE) response to mild and moderate treadmill exercise in awake goats. Accordingly, we measured CV and respiratory responses to two levels of exercise in seven normal (N) and six cardiac-denervated (CD) goats. Evidence of surgical CD included 1) absence of a cardiac response during surgery when the left thoracic cardiac nerves, thoracic vagi, and right and left stellate ganglia were electrically stimulated, 2) total and 80% attenuation of baroreflex changes in heart rate (HR) when arterial blood pressure was raised or lowered, respectively, by infusion of vasoactive agents in awake goats, and 3) attenuation of the CV responses to exercise. At each level of exercise in the CD goats, the HR response was significantly reduced relative to the response observed before CD (P less than 0.05) and the recovery HR response was delayed. Cardiac index increased in a work rate-dependent manner in N and CD goats but was significantly lower in the CD animals (P less than 0.05). Hypotension was consistently observed during exercise following CD. There was no effect of CD on steady-state VE at any metabolic rate or on the VE-O2 uptake relationship (P greater than 0.05). The rest-to-work and work-to-work transition responses of arterial PCO2 were similar between N and CD goats, but there was a tendency toward greater hypocapnia at the exercise onset in CD goats at the highest work rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Differential effect of ventrolateral medullary cooling on respiratory muscles of goats.

The objective was to determine whether there is an inhomogeneous response of respiratory muscles during cooling-induced ventrolateral medullary (VLM) neuronal dysfunction in anesthetized and awake goats. Thermodes for cooling were chronically implanted on all or portions of rostral, intermediate, and caudal areas of the VLM of 16 adult goats. Electromyograms (EMGs) were obtained from chronically implanted wires in the diaphragm (di), transversus abdominis (TA), and triangularis sterni (TS) muscles. During some periods of cooling in 9 of 16 anesthetized airway-intubated goats, complete cessation of EMGdi coincided with a reduced yet sustained inspiratory flow. In six awake tracheotomized goats, VLM cooling decreased (P < 0.05) EMGdi duration and minute activity more than inspiratory duration and minute ventilation. Cooling thus decreased activation of the diaphragm more than activation of other respiratory muscles. On the other hand, during VLM cooling in 3 of 10 airway-intact awake goats, cessation of inspiratory flow coincided with sustained EMGdi, suggesting that cooling decreased stimulation of the upper airway muscles more than stimulation of the diaphragm. Finally, VLM cooling in a majority of goats decreased EMGTA and EMGTS more than EMGdi. We conclude that VLM neuronal dysfunction has a differential effect on respiratory muscles of adult anesthetized and awake goats.

Anesthesia↗

PubMed2003

Perturbations in three medullary nuclei enhance fractionated breathing in awake goats.

Our aim was to determine the frequency and characteristics of a fractionated pattern of diaphragm and upper airway muscle activity and airflow during wakefulness and sleep in adult goats. A fractionated breath (FBr) was defined as three or more brief (40-150 ms) interruptions in the diaphragm activity not associated with multiple swallows, eructation, mastication, or movement. During a FBr, the discharge pattern in the diaphragm and upper airway muscles showed complete cycles of inspiration and expiration. Whereas the interval between peak diaphragm activity of the breath preceding the FBr to the first diaphragm peak of the FBr was 15-20% less than the average interval of the preceding five control breaths, the breath-to-breath interval of the five breaths after a FBr did not differ from the control breaths before the FBr event. In normal goats, FBr was evident in only 4 of 18 (22%) awake goats and in only one of these goats during non-rapid eye movement sleep. In 35 goats with implanted microtubules in the medulla, FBr were present in 14 (40%) goats. In these goats with FBr, 78% (11 of 14) had one or more implantations into or near the facial, vestibular, or raphe nuclei. The effect of perturbations in these nuclei is probably nonspecific, because injections into these nuclei with mock cerebrospinal fluid or excitatory amino acid-receptor agonist or antagonist produced both increases and decreases in the frequency of the FBr while not altering their characteristics. Finally, a swallow occurred at the termination or during the first breath after 60% of the FBr. We speculate that the FBr manifest 1) the disruption of a neuronal network, which coordinates breathing and other functions (such as swallowing), utilizing the same anatomic structures, and/or 2) transient changes in synaptic inputs that increase the rate of the normal respiratory rhythm generator or allow an ectopic, anomalous generator to become dominant.

Animals↗

PubMed2004

Large lesions in the pre-Bötzinger complex area eliminate eupneic respiratory rhythm in awake goats.

In awake goats, 29% bilateral destruction of neurokinin-1 receptor-expressing neurons in the pre-Bötzinger complex (pre-BötzC) area with saporin conjugated to substance P results in transient disruptions of the normal pattern of eupneic respiratory muscle activation (Wenninger JM, Pan LG, Klum L, Leekley T, Bastastic J, Hodges MR, Feroah T, Davis S, and Forster HV. J Appl Physiol 97: 1620-1628, 2004). Therefore, the purpose of these studies was to determine whether large or total lesioning in the pre-BötzC area of goats would eliminate phasic diaphragm activity and the eupneic breathing pattern. In awake goats that already had 29% bilateral destruction of neurokinin-1 receptor-expressing neurons in the pre-BötzC area, bilateral ibotenic acid (10 microl, 50 mM) injection into the pre-BötzC area resulted in a tachypneic hyperpnea that reached a maximum (132 +/- 10.1 breaths/min) approximately 30-90 min after bilateral injection. Thereafter, breathing frequency declined, central apneas resulted in arterial hypoxemia (arterial Po2 approximately 40 Torr) and hypercapnia (arterial Pco2 approximately 60 Torr), and, 11 +/- 3 min after the peak tachypnea, respiratory failure was followed by cardiac arrest in three airway-intact goats. However, after the peak tachypnea in four tracheostomized goats, mechanical ventilation was initiated to maintain arterial blood gases at control levels, during which there was no phasic diaphragm or abdominal muscle activity. When briefly removed from the ventilator (approximately 90 s), these goats became hypoxemic and hypercapnic. During this time, minimal, passive inspiratory flow resulted from phasic abdominal muscle activity. We estimate that 70% of the neurons within the pre-BötzC area were lesioned in these goats. We conclude that, in the awake state, the pre-BötzC is critical for generating a diaphragm, eupneic respiratory rhythm, and that, in the absence of the pre-BötzC, spontaneous breathing reflects the activity of an expiratory rhythm generator.

Animals↗

PubMedDate not supplied

In vivo and In vitro studies on the cerebrovascular dilatation induced by diazoxide in normotensive and renal hypertensive goats.

We studied the in vivo and in vitro effects of diazoxide on the cerebral circulation of 8 normotensive (mean arterial pressure = 100 mm Hg) and 5 renal hypertensive (mean arterial pressure = 146 mm Hg) goats. Injections of diazoxide (0.3-27 mg) into the internal maxillary artery of unanesthetized goats produced dose-dependent increases in cerebral blood flow (electromagnetic flowmeter), this effect being significantly higher in hypertensive goats. Intravenous injection of 5 mg/kg of diazoxide into normotensive goats increased cerebral blood flow 40 ml/min/100 g and mean arterial pressure dropped 22 mm Hg whereas in hypertensive goats cerebral blood flow was unchanged and mean arterial pressure decreased 50 mm Hg. The increase in heart rate due to intravenous diazoxide was similar in normotensive and hypertensive goats (35 beats/min). Cumulative applications of diazoxide (10(-5) to 10(-3)M) on isolated middle cerebral arteries produced dilatory responses both under resting conditions and after previous tonic contraction by serotonin. This relaxation was significantly greater in arterial segments from hypertensive goats. The results indicate that diazoxide exerts powerful dilatatory effects on cerebral vessels, both in vivo and in vitro, and that these effects are particularly evident in hypertensive animals.

Animals↗

PubMed2006

An outbreak of Streptococcus equi subspecies zooepidemicus associated with consumption of fresh goat cheese.

BACKGROUND: Streptococcus equi subspecies zooepidemicus is a rare infection in humans associated with contact with horses or consumption of unpasteurized milk products. On October 23, 2003, the National Public Health Institute was alerted that within one week three persons had been admitted to Tampere University Central Hospital (TaYS) because of S. equi subsp. zooepidemicus septicaemia. All had consumed fresh goat cheese produced in a small-scale dairy located on a farm. We conducted an investigation to determine the source and the extent of the outbreak. METHODS: Cases were identified from the National Infectious Disease Register. Cases were persons with S. equi subsp. zooepidemicus isolated from a normally sterile site who had illness onset 15.9-31.10.2003. All cases were telephone interviewed by using a standard questionnaire and clinical information was extracted from patient charts. Environmental and food specimens included throat swabs from two persons working in the dairy, milk from goats and raw milk tank, cheeses made of unpasteurized milk, vaginal samples of goats, and borehole well water. The isolates were characterized by ribotyping and pulsed-field gel electrophoresis (PFGE). RESULTS: Seven persons met the case definition; six had septicaemia and one had purulent arthritis. Five were women; the median age was 70 years (range 54-93). None of the cases were immunocompromized and none died. Six cases were identified in TaYS, and one in another university hospital in southern Finland. All had eaten goat cheese produced on the implicated farm. S. equi subsp. zooepidemicus was isolated from throat swabs, fresh goat cheese, milk tank, and vaginal samples of one goat. All human and environmental strains were indistinguishable by ribotyping and PFGE. CONCLUSION: The outbreak was caused by goat cheese produced from unpasteurized milk. Outbreaks caused by S. equi subsp. zooepidemicus may not be detected if streptococcal strains are only typed to the group level. S. equi subsp. zooepidemicus may be a re-emerging disease if unpasteurized milk is increasingly used for food production. Facilities using unpasteurized milk should be carefully monitored to prevent this type of outbreaks.

Aged↗

PubMed2006

Immunization of goats against inhibin increased follicular development and ovulation rate.

In the present study, two experiments were conducted to induce superovulation in goats using passive and active immunization against inhibin. In the first experiment, two groups of goats were given an intravenous injection of either 10 ml normal goat serum (control; n=6) or inhibin antiserum developed against [Tyro30]-inhibin alpha (1-30) (passively immunized; n=6) 48 h before treatment with PGF2alpha. In the second experiment, two groups of goats were immunized with inhibin vaccine (actively immunized; n=5) or Freund's adjuvant (control; n=5) followed by three booster immunizations at 4 week intervals. Blood samples were collected for determination of FSH, LH, estradiol-17beta, and progesterone. Ultrasonography was used to determine ovarian activity at PGF2alpha injection and ovulation rate one week after estrus. In both experiments, there was a significant increase in plasma FSH concentration compared with the controls. However, the pattern of the FSH levels was different between the passively and actively immunized goats. The numbers of follicles in passively and actively immunized goats (22.4 +/- 2.3 and 18.6 +/- 2.1, respectively) were significantly greater than those in the controls (2.6 +/- 0.4 and 2.3 +/- 0.4, respectively). In addition, the ovulation rate was greater in the immunized animals compared with the controls. Therefore, either passive or active immunization against inhibin could be used to induce superovulation in goats.

Animals↗

PubMed2003

Origin of plasma insulin-like growth factor-I (IGF-I) during estrus in goats.

The objective of this study was to clarify the origin of the increase in plasma insulin-like growth factor-I (IGF-I) during estrus in goats. Focusing on the uterus, the effect of estradiol-17 beta (E2) on the secretion of IGF-I was examined using ovariectomized and hysterectomized animals. A single 5 microg/kg BW of E2 was injected intramuscularly into ovariectomized and hysterectomized goats for 3 consecutive days, and plasma IGF-I concentrations in the two groups were compared. The concentrations of IGF-I rose after the treatments in both groups. The concentrations were significantly higher from 3 to 8 days after the treatment than before the treatment in ovariectomized goats (P<0.05), and from 1 to 3 days after the treatment than before in hysterectomized goats (P<0.05). Thus higher concentrations of plasma IGF-I tended to last longer in ovariectomized than hysterectomized goats. The area under the IGF-I response curve for the 8-day period after the first injection of E2 tended to be greater in ovariectomized than in hysterectomized goats. The results show that E2 increases plasma IGF-I concentrations in goats, and suggest that E2-stimulated IGF-I in plasma may originate mainly from the uterus.

Animals↗

PubMed1985

Prenatal diagnosis of a thyroglobulin synthesis defect in goats.

A strain of goats with congenital goitre due to a thyroglobulin (Tg) synthesis defect was studied. All goats excreted low molecular weight iodinated material (LOMWIOM) in their urine, but non-goitrous goats excreted in the LOMWIOM fraction less than 5 micrograms iodine per 24 h and the goitrous ones more than 15 micrograms iodine per 24 h. Prenatal diagnosis of the Tg synthesis defect in goats is possible since non-goitrous goats pregnant with goitrous kids excrete in the LOMWIOM fraction more than 10 micrograms iodine per 24 h while non-goitrous goats pregnant with non-goitrous kids excrete 10 micrograms or less iodine per 24 h as LOMWIOM. In 24 out of 25 cases a correct diagnosis could be made in the last 47 days of pregnancy. We argue that prenatal diagnosis of analogous defects in man may also be possible, using the excretion of LOMWIOM in maternal urine as yard-stick. By means of field desorption mass spectrometry (FOMS) and high performance liquid chromatography (HPLC) monoiodohistidine was identified as the major component of the LOMWIOM fraction in the urine of goitrous goats.

Animals↗

PubMed1997

Parathyroid hormone-related protein in neonatal and reproductive goats determined by a sensitive time-resolved immunofluorometric assay.

OBJECTIVE: High concentrations of parathyroid hormone-related protein (PTHrP) have been found in goat milk but it is not known whether it can enter the circulation of the neonate. In this study we have developed a sensitive two-site lanthanide immunofluorometric assay (IFMA) using dissociation and enhancement time-resolved fluorometry to address this question. METHOD: Affinity-purified anti-PTHrP 38-67 raised in rabbit was biotinylated and immobilized in streptavidin-coated microtitration wells as a 'capture' antibody. As a signal, affinity-purified anti-PTHrP 1-34, raised in sheep, was labeled with an europium chelate. A sensitivity of 0.3 pmol/l was achieved. PTHrP levels were determined in the plasma of eleven neonatal, seven parturient and six non-pregnant, non-lactating goats as well as in goat milk. RESULTS: The circulating PTHrP levels (mean +/- S.D.) were significantly increased at day 1 (6.1 +/- 1.7 pmol/l: P < 0.01) and day 3 (3.5 +/- 0.6 pmol/l: P < 0.05) after birth in the male kids (n = 8) bottle-fed with milk from the dams, compared with before (2.2 +/- 0.7 pmol/l) and 30 min after (2.0 +/- 0.6 pmol/l) the first feeding and 14 days (2.4 +/- 0.8 pmol/l) later. In the female kids (n = 3) fed with formula there was no such increase and the concentrations remained between 1.6-1.9 pmol/l. In the parturient goats the mean +/- S.D. PTHrP levels before, during and after parturition were 2.9 +/- 1.7, 4.2 +/- 2.4 and 3.7 +/- 2.2 pmol/l respectively (n = 7) which demonstrated that plasma PTHrP was higher during and after parturition in comparison with before (P < 0.05). The levels in non-pregnant, non-lactating goats were 3.3 +/- 1.5 pmol/l (n = 6). PTHrP levels in goat milk were in the nanomolar range and were highest in the colostrum. CONCLUSIONS: A significant increase of plasma PTHrP was observed in goat kids fed with milk from their dams and this increase was not found in kids fed with formula. Plasma PTHrP was also increased during parturition.

Aging↗

PubMed1990

Pregnancy-specific protein B and progesterone concentrations in French Alpine goats throughout gestation.

The 34 French Alpine dairy goats originated from a single flock and were artificially inseminated 44 h after synchronization of oestrus. They were bled daily at the jugular vein from 15 to 27 days after AI. An early pregnancy diagnosis by RIA of progesterone concentration was performed 21 days after AI. In pregnant goats (greater than 1.5 ng progesterone/ml) daily sampling was extended until 30 days after AI and, from those, 9 were bled every 2 weeks until the end of pregnancy and at 50 and 63 days post partum. Pregnancy-specific protein B (PSPB) was also assayed. The kidding rate was 67.6% (23/34). PSPB concentrations (ng/ml) in pregnant goats were significantly different from those of non-pregnant goats at 24 days after AI (0.82 +/- 0.18 vs 1.78 +/- 0.19; mean +/- s.e.m.) and rose to 40 ng/ml at the end of pregnancy. From Day 25 and throughout gestation, females with 2 fetuses had higher PSPB concentrations than did those with a single fetus (P less than 0.05). In the 2 goats exhibiting late embryonic mortality according to progesterone concentrations, one had a PSPB profile very similar to those of pregnant goats until 30 days while the other did not show any elevation of PSPB concentration. It is concluded that PSPB profiles in goats are similar to those found in cows throughout pregnancy and that PSPB RIA may be useful for pregnancy diagnosis or diagnosis of late embryonic mortality.

Animals↗

PubMed2005

Alterations in follicular dynamics and steroidogenic abilities induced by heat stress during follicular recruitment in goats.

We investigated the changes in follicular dynamics and steroidogenic activity during heat stress in goats. Adult female goats were exposed to heat stress at 36 degrees C and 70% relative humidity for 48 h and then injected with prostaglandin (PG) F2alpha (the time of PGF2alpha injection was designated as 0 h). In experiment 1, every follicle greater than 2 mm in diameter was monitored by ultrasonography to investigate the follicular dynamics, and plasma concentrations of FSH, LH, progesterone, and oestradiol were measured from -48 h to 120 h. In experiment 2, the follicles were recovered from the goats at 48 h, and the concentration of oestradiol, the aromatase activity, and the LH receptor level in the follicles were determined. In control (non-heat-stressed) goats, ovulatory follicles were mainly recruited from -24 h to 0 h, whereas no follicles recruited during that period were ovulated in the heat-stressed goats. The timing of the recruitment of ovulatory follicles was delayed by heat stress by approximately 24 h. The plasma concentration of oestradiol in the heat-stressed goats was significantly lower from 36 to 54 h compared with the controls, although the concentrations of FSH and progesterone did not differ between the treatments. In addition, the concentration of oestradiol, the aromatase activity, and the LH receptor level in the follicles from heat-stressed goats were significantly lower compared with the controls. These results indicate that heat stress during follicular recruitment suppresses subsequent growth to ovulation, accompanied by decreased LH receptor level and oestradiol synthesis activity in the follicles.

Animals↗

PubMed1975

Metabolic clearance rate, production rate and mammary uptake of progesterone in the goat.

The dynamics of progesterone uptake and metabolism in the mammary gland of the goat have been measured and related to the metabolic clearance rate and production rate of the hormone determined by tracer kinetic techniques. The metabolic clearance rate of progesterone from blood was 3-13 plus or minus 0-35 (S.E.M.) 1/min in ten experiments on six goats; values tended to be slightly higher in pregnant than in non-pregnant goats. The production rate of progesterone at oestrus, and at day 3 of the normal cycle, was less than 0-01 mug/min. During the luteal phase of the oestrous cycle the production rate was 8-5 and 14-6 mug/min in 2 animals, and in the second half of pregnancy, 15-3 plus or minus 0-6 mug/min (5 animals). Progesterone was extracted from the circulation by the mammary gland of conscious goats with an efficiency of 49-4 plus or minus 11-3% in non-pregnant, and 51-7 plus or minus 11-5% in pregnant aniamals. The mean clearance rate of progesterone by the udder was 0-279 1/min, 8-8% of the metabolic clearance rate. Mammary uptake of progesterone in goats with an actively secreting corpus luteum was 0-64 plus or minus 0-29 mug/min, which gave an estimated value of 0-11-1-88 ng/min/g mammary gland. The mammary extraction of progesterone was investigated in a goat 3 days after oestrus when any high affinity receptor sites would presumably be unoccupied. During the infusion of progesterone into a mammary artery, tissue sample were taken from various organs, including the mammary gland, and the concentration of labelled compounds at steady state was determined. A high mammary extraction of progesterone was found to be determined. A high mammary extraction of progesterone was found to be attributable principally to progesterone metabolism. The metabolites of progesterone were removed from the gland in venous blood and were not stored to any appreciable extent in mammary tissue. Experiments in vitro confirmed the findings in vivo that mammary tissue metabolized labelled progesterone and also pregnenolone and androstenedione; metabolism of dehydroepiandrosterone, oestradiol-17 beta, oestrone and cortisol was relatively small. Confirmation of our previous finding that the mammary gland of the goat can synthesize progesterone from labelled pregnenolone infused into the gland in vivo, further implicated this organ as an active site of metabolism of certain steroids. The physiological role of steroid metabolism in the mammary gland is discussed.

Androstenedione↗

PubMed1985

Hormone concentrations, mammary development and milk yield in goats given long-term bromocriptine treatment in pregnancy.

Ten British Saanen goats were treated daily with 5 mg bromocriptine intramuscularly from week 8 of pregnancy until week 20 (day 140). By comparison with untreated control goats (n = 8), concentrations of prolactin in plasma were suppressed throughout the treatment period and remained significantly lower until 3 days prepartum, parturition occurring on day 153 +/- 0.7 (mean +/- S.E.M., n = 10). Growth hormone concentrations were low, but the incidence of levels exceeding 1 microgram/l was increased in bromocriptine-treated goats. Plasma concentrations of placental lactogen, progesterone and oestrone sulphate were unaffected. The accumulation of pre-colostrum in the udder (lactogenesis stage I) was not affected by bromocriptine treatment in goats carrying twin fetuses, but in goats with single kids it was delayed by about 4-6 weeks to week 17 of pregnancy. Secretion could not be expressed from the udder and the concentration of alpha-lactalbumin in plasma remained low. Udder volume was significantly reduced in week 15-16 but not week 20-21 of pregnancy by bromocriptine treatment. Milk yields after 50 or 203 days of lactation were not significantly different from those in control goats. Placental lactogen concentrations in late pregnancy and udder volume in week 20-21 were the only variables measured which correlated with milk yield post partum. It is concluded that in vivo placental lactogen is an effective mammotrophic hormone, although less potent than prolactin as evidenced by the delay in lactogenesis stage I in bromocriptine-treated goats bearing single kids.

Animals↗

PubMed1987

Passive immunization of pregnant goats against ovine LH.

Groups of three goats at 50, 90 and 130 days of gestation were passively immunized against ovine LH (oLH) by i.v. infusion of 8 ml serum equivalent of the immunoglobulin fraction of rabbit anti-oLH serum (LHAS). Goats at the same stages of gestation as above served as controls and received 8 ml serum equivalent of the immunoglobulin fraction of normal rabbit serum (NRS). Plasma concentrations of progesterone were determined by specific radioimmunoassay of blood collected at 20-min intervals from 6 h before infusion of LHAS or NRS to 12 h after infusion. Less frequent sampling was performed from 2 days before to 6 days after infusion. Plasma from all LHAS-immunized goats exhibited binding of oLH. Twelve hours after immunization, titres ranged from 1:135 to 1:215. All LHAS-treated goats had titres of less than 1:10 by 5 days after immunization, but a low level of oLH binding was still detectable. Treatment with LHAS or NRS did not shorten the length of gestation, with all goats delivering live offspring between 142 and 147 days after conception. Plasma concentrations of LH ranged from less than 0.15 micrograms/l to 4.8 micrograms/l and were greater than 0.15 micrograms/l in 181 of 255 samples (71%) for both the NRS-treated group, throughout the experiment, and the LHAS-treated groups before infusion of antiserum. Luteinizing hormone was not detectable in plasma samples obtained after LHAS infusion in goats at 50 or 130 days of pregnancy. Plasma concentrations of LH exceeded 0.15 micrograms/l in only five of 51 (10%) samples in 90-day-pregnant goats treated with LHAS, the maximum value reached being 0.80 micrograms/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

The regulation of oxidative drug metabolism by growth hormone in the dwarf goat: differences from and similarities to the mechanisms in rats.

The effects of bovine GH (BST), administered in different dose patterns, on in-vivo oxidative drug metabolism, were studied in female dwarf goats. Animals received recombinantly derived methionyl BST at a dose of 500 micrograms/kg body weight per 24 h for 6 days. It was administered to one group of goats as one s.c. injection per day, another group received a similar 24-h dose divided into three s.c. injections given at 8-h intervals, and the third group received 50 micrograms BST/kg body weight every 2.5 h by a pulsative i.v. infusion. Oxidative metabolic capacity was assessed by determining plasma sulphadimidine (SDD) elimination and urinary metabolite excretion. SDD shows a marked sex-dependent plasma elimination in dwarf goats, with male goats having a lower plasma clearance than female goats. When BST was given by daily injection, no clear effects on SDD plasma clearance or urinary metabolite excretion were observed. However, when the total dose was divided into three injections given at 8-h intervals, the plasma SDD elimination rate decreased. This was associated with a decrease in urinary excretion of the two main hydroxy SDD metabolites. When BST was given by discontinuous i.v. infusion, simulating the male endogenous plasma GH pattern, a marked decrease in SDD plasma clearance was observed. In addition, the excretion of the two urinary hydroxy metabolites was considerably reduced. These results suggest that GH can affect drug oxidation in dwarf goats via mechanisms similar to those suggested for rats. However, in the dwarf goat, the sex differences in drug metabolism are opposite to those in rats.

Animals↗