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PubMed2001

Persistent ovarian follicles in dairy cows: a therapeutic approach.

Anestrus is common during the postpartum period in high-producing dairy cows. In a previous investigation, we were able to diagnose persistent follicles of 8 to 12 mm in anestrous cows. This report describes 2 consecutive studies. The objectives of the first were to 1) assess the association of persistent follicles with anestrus; and 2) evaluate 2 therapeutic treatments. In the second study, we compared the effectiveness of the best treatment established in Study 1 with the Ovsynch protocol. For Study 1, anestrous cows were considered to have a persistent follicle if it was possible to observe a single follicular structure > 8 mm in the absence of a corpus luteum or a cyst in 2 ultrasonographic examinations performed at an interval of 7 d. At diagnosis (Day 0), cows were assigned to 1 of 3 treatment groups. Cows in Group GnRH/PGF (n=17) were treated with 100 microg GnRH i.m., and 25 mg PGF2alpha i.m. on Day 14. Cows in Group PRID (n=18) were fitted with a progesterone releasing intravaginal device (PRID, containing 1.55 g of progesterone) for 9 d and were given 100 microg GnRH i.m. at the time of PRID insertion, and 25 mg PGF2alpha i.m. on Day 7. Cows in Group Control (n=18) received no treatment. The animals were inseminated at observed estrus and were monitored weekly by ultrasonography until AI or 5 weeks from diagnosis. Blood samples were also collected on a weekly basis for progesterone determination. The mean size of persistent follicles on Day 0 was 9.4 +/- 0.04 mm. Progesterone levels were < 0.2 ng/mL during the first 35 d in 16 of 18 Control cows. Cows in the PRID group showed a lower persistent follicle rate (16.7% < 70.6% < 88.9%; P < 0.0001; PRID vs GnRH/PGF vs Control, respectively); a higher estrus detection rate (83.3% > 29.4% > 11.1%; P < 0.0001) and a higher pregnancy rate (27.8% > 5.9% > 0%; P = 0.02). For the second study, 145 cows with persistent follicles were randomly assigned to 1 of 2 treatment groups: cows in Group Ovsynch (n=73) were treated with 100 microg GnRH i.m. on Day 0, 25 mg PGF2alpha i.m. on Day 7, and 100 microm GnRH i.m. 32 h later. Cows in this group were inseminated 16 to 20 h after the second GnRH dose (Ovsynch protocol). Cows in Group PRID (n=72) were treated as those in the PRID group of Study 1, and were inseminated 56 h after PRID removal. Cows in the PRID group showed a higher ovulation rate (84.8% > 8.2%: P < 0.0001); a higher pregnancy rate (34.2% > 4.1%; P < 0.0001) and lower follicular persistence rate (22.2% < 63%; P < 0.0001) than those in Ovsynch. Our results indicate that persistent follicles affect cyclic ovarian function in lactating dairy cows. Cows with persistent follicles can be successfully synchronized and time inseminated using progesterone, GnRH and PGF2alpha but show a limited response to treatment with GnRH plus PGF2alpha.

Anestrus↗

PubMed1990

Proliferative changes in the genital tissue of female mice during the oestrous cycle.

Changes in proliferation and number of epithelial cells of the murine genital tract, during the oestrous cycle, have been studied. A total of 47 animals in the prooestrous, metoestrous and dioestrous phases of the cycle were staged retrospectively on the basis of the genital tract histology. The average duration of the oestrous cycle in these animals was 4 days, and half of this period was occupied by the prooestrous/oestrous phases. Significant cycles of growth were observed in the luminal uterine epithelium and in the basal epithelium of the cervix-vagina. Most of this growth occurred during the pro-oestrous phase, which lasted approximately 1 day. During this time the numbers of luminal epithelial cells in the uterus and suprabasal cells in the cervix-vagina increased 2-3 fold. This pattern of growth appeared partly synchronous and corresponded to the period when serum oestrogen levels are at their highest. A corresponding and rapid reduction in the numbers of uterine luminal epithelial cells and suprabasal cells in the cervix and vagina was noted during the early metoestrous phase; and this occured during the period when serum oestrogens are at their lowest levels. No significant periodicity in the proliferation and numbers of the uterine gland epithelial cells was noted during the cycle. The kinetic role and function of the gland cells is discussed in relation to these data.

Animals↗

PubMed1975

Effects of prostaglandin F2alpha on the oestrous cycle and pregnancy in mares.

Several experiments indicated that prostaglandin F2alpha (PGF2alpha) has luteolytic and abortifacient properties in mares. A single subcutaneous injection of 1-25 mg PGF2alpha on Day 6 of dioestrus was as effective as 10 mg PGF2alpha in inducing luteolysis. Oestrus and ovulation appeared to be synchronized when a single injection of 1-25 mg PGF2alpha was given on Days 7, 10 or 13 after ovulation but not on Days 1 or 4 after ovulation or on Day 2 of oestrus. Intramuscular administration was as effective as subcutaneous administration and 1-25 mg PGF2alpha was the minimal effective systemic dose to induce luteolysis. Administration of PGF2alpha into the uterus or directly into the CL did not improve the luteolytic efficacy of the intramuscular injection of PGF2alpha. All thirteen mares aborted following injections of 2-5 mg PGF2alpha at 12-hr intervals; an average of 3-7 injections were given before abortion occurred.

Abortion, Induced↗

PubMed1985

Control of pig reproduction in a breeding programme.

Important improvements in the management of sows have been made over the past 20 years in Europe and the U.S.A. Nevertheless, annual productivity varied between 15 and 25 piglets weaned per sow per year in France for 1983. Reasons for such a difference in productivity have been analysed quantitatively. Marked differences exist between herds in the genotype of pig used and in the age of puberty. Transportation acts as a stress stimulus and stimulates puberty attainment. However, there is variability in the occurrence of oestrus amongst different purchased batches of pigs. Recent endocrine results led to four phases in sexual maturation of gilts being distinguished (perinatal, infancy, activation and resting) and permitted a better understanding of the variation in the onset of puberty. After a lactation of 3 weeks or more, about 25% of primiparous sows did not return to oestrus within 1 week of weaning. Fertility of these sows with a delayed oestrus was 10% lower than in sows having a normal oestrus after weaning. The past 3 decades of research on control of ovulation have yielded positive results. However, there is no satisfactory method for the induction of puberty. One method used to regulate the oestrous cycle in gilts is treatment with a progestagen. This method is still available commercially in France. The close synchronization obtained with a progestagen treatment has led to the use of AI at fixed days (Days 6 and 7) in crossbred gilts but not for purebred gilts. Some environmental factors (e.g. male stimulation, age of gilts at treatment, diet and month of AI) have been analysed to evaluate their effects on farrowing rate and litter size. After weaning, a short treatment with a progestagen (20 mg/day) tends to improve the synchronization of oestrus (3-9 days), especially in primiparous sows. Farrowing rate and litter size are similar in treated sows and control sows. However, this technique does not permit fixed-time AI without detection of oestrus. Diagnosis of pregnancy was successful with ultrasound scanning. This technique can be performed 20 days after insemination if the sow is tied up during the examination and at 22 days if the sow is restrained in a retention box. From 22 days after mating, errors made for positive and negative diagnoses were less than 5%. These techniques contribute to a better control of reproduction in different management systems.

Animal Husbandry↗

PubMed1975

The effects of nutrition on the reproductive performance of Finn x Dorset ewes. II. Post-partum ovarian activity, conception and the plasma concentration of progesterone and LH.

After lambing forty-five ewes were allocated to three groups, two of sixteen and one of thirteen ewes. The lambs of the two groups of sixteen ewes were weaned on Day 1 after lambing and the ewes were fed a diet of 100% (Group H) or 50% (Group R) of maintenance energy requirements. The thirteen ewes in the third group (Group L) suckled twin lambs and were fed freely. During the first 3 weeks after lambing, oestrus was observed for 11/16 (Group H) and 8/16 (Group R) ewes; of the ewes which had shown oestrus in the two groups, ovulation occurred in 5/8 and 5/7 respectively. Only 1/13 Group-L ewes showed oestrus and ovulated during the same period. The mean plasma concentrations of progesterone and LH were unaffected by the treatments and were around 0-4 and 1-5 ng/ml, respectively. Restricted feeding had no effect on oestrus, ovulation or the hormone levels during the oestrus cycle following synchronization. The onset of oestrus and the start of the preovulatory discharge of LH were 3 and 6 hr later, respectively, in the lactating ewes (Group L) than in those in Groups H and R. Ewes in Group L also had a higher ovulation rate, 2-8 +/- 0-2 versus 2-1 +/- 0-2 (P less than 0-05). Restricted feeding reduced the number of ewes lambing; only 1/11 ewes in Group R, considered to have conceived because of the presence of high progesterone levels 17 days after mating, subsequently lambed compared with 6/12 in Group H and 5/9 in Group L.

Animal Nutritional Physiological Phenomena↗

PubMed1987

Plasma patterns of LH, FSH and prolactin in rats with a polycystic ovarian condition induced by oestradiol valerate.

The patterns of plasma LH, FSH and prolactin concentrations were investigated in rats with a polycystic ovary condition (PCO). The condition was induced by treatment with oestradiol valerate 9 weeks before blood sampling. Serial blood samples were taken at 10-min intervals for 4 h from ten rats with PCO. All samples were assayed for LH, those from five animals for FSH and those from the remaining five animals for prolactin. In addition, five control animals with normal oestrous cycles were sampled during oestrus and the samples assayed for LH. Mean concentrations of LH, FSH and prolactin in rats with PCO were 140 ng/l, 76 micrograms/l and 7.6 micrograms/l respectively. All three hormones exhibited an episodic pattern. The mean peak amplitudes of LH, FSH and prolactin were 120 ng/l, 25 micrograms/l and 3.5 micrograms/l respectively. All three hormones exhibited a similar mean frequency of four or five episodes per 4 h. The LH and FSH patterns were closely synchronized; nearly all FSH peaks coincided with LH peaks. The prolactin pattern did not, however, correlate with that of the gonadotrophins. Despite the persistent oestrous condition of the animals with PCO, it was clear that their pattern of LH did not resemble that of cyclic animals in normal oestrus; in the normally cyclic animals in oestrus the pulse period was nearly twice as long and the pulse amplitude was more than sixfold greater than those in animals with PCO. We conclude that the unique episodic patterns of gonadotrophins are more important than mean blood concentrations of these hormones in establishing and maintaining the polycystic ovary syndrome.

Animals↗

PubMed1999

Serum prolactin concentrations in the captive female African elephant (Loxodonta africana): potential effects of season and steroid hormone interactions.

Research was conducted to determine whether seasonal changes in prolactin secretion occur in nonpregnant female African elephants and to examine potential functional interrelationships between secretion of prolactin, cortisol, and progesterone. Weekly blood samples were taken for 18 months from four female African elephants and the sera were analyzed by RIA for progesterone, cortisol, and prolactin concentrations. There was no significant effect of season on serum concentrations of prolactin. Estrous cycles averaged 14 weeks in length and were composed of a 9-week luteal phase and a 5-week follicular phase (based on progesterone concentrations consistently >200 and <200 pg/ml, respectively). Estrous cycle synchronicity was evident between pairs of elephants. Serum concentrations of prolactin (3.91 +/- 0.69 ng/ml; range: 0.84-15.8 ng/ml) were significantly lower during the luteal, compared with the follicular, phase (P < 0.0001; t test) and were positively correlated with serum concentrations of cortisol (r = 0.14; P < 0.05). Mean (+/-SE) serum concentration of cortisol was 5.7 +/- 1.3 ng/ml (range: 1.4-19.3 ng/ml), and concentrations of this adrenal steroid were negatively correlated with progesterone concentrations (r = -0.15; P < 0.01). Increased serum concentrations of prolactin detected during the follicular phase suggest that this hormone may be regulated by ovarian estrogens and may play a role in modulating ovarian function in the elephant.

Animals↗

PubMed1991

Social control of reproduction in breeding and non-breeding male naked mole-rats (Heterocephalus glaber).

Eight male naked mole-rats, from three colonies were studied in captivity. When non-breeding male naked mole-rats were removed from their colonies and paired with a non-breeding female, or removed and housed singly for 6 weeks before pairing with a female, concentrations of urinary testosterone and plasma luteinizing hormone (LH) increased significantly (P less than 0.05). Concentration of these hormones were highest while the males were singly housed: urinary testosterone (mean +/- s.e.m.) increased from 8.2 +/- 1.3 ng/mg urinary creatinine (Cr) in a non-breeder in a colony to 49.1 +/- 5.5 ng/mg Cr when singly housed and 21.8 +/- 2.5 ng/mg Cr when paired with a female. Plasma LH concentrations increased from 4.7 +/- 1.0 miu/ml when a non-breeder in a colony to 19.8 +/- 4.0 miu/ml when singly housed and 9.9 +/- 1.1 miu/ml when paired with a female. After pairing with a female, the pattern of urinary testosterone secretion in the male was synchronized with the ovarian cycle of the female mate, such that urinary testosterone concentrations were significantly higher during the early follicular phase of the female's cycle (P less than 0.05). These results suggest that active suppression of reproductive physiology by social cues occurs in non-breeding male naked mole-rats, and that this is readily reversible if social cues are removed and males are housed singly. When a male was subsequently paired with a female, endocrine suppression was partially reimposed on the reproductively active males, such that urinary testosterone concentrations were suppressed to values similar to those in non-breeding males, except for periods prior to mating.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Thermoregulatory effects and electrical conductivity in vagina of cow during oestrous cycle.

Measurement of vaginal temperature and electrical conductivity of cervicovaginal mucus were conducted in 20 dairy cows and were related to the phase of the oestrus cycle. Temperature and electrical conductivity in the anterior part of the vagina changed in synchronicity with phases of the oestrous cycle. About 12 hours before ovulation, the vaginal temperature increased from 37.94 +/- 0.33 degrees C to 39.00 +/- 0.64 degrees C, as compared to the pre-oestrus value. The occurrence of oestrus was accompanied by an increase in electrical conductivity of mucus in the anterior part of the vagina from 7.60 +/- 0.33 mS to 12.00 +/- 0.54 mS. Vaginal temperature dropped to 38.50 +/- 0.29 degrees C, and electrical conductivity dropped to 10.00 +/- 0.55 mS at ovulation time. Rises in vaginal temperature and electrical conductivity in the anterior part of the vagina were additional symptoms of oestrus and were followed by decrease in these values, indicating ovulation in cows.

Animals↗

PubMed2000

Appearance of a nocturnal peak of leptin secretion in the pubertal rat.

Whether leptin is involved in the timing of puberty remains highly controversial in the rat. Daytime leptin secretion shows little change during the transition into adulthood. Because leptin exhibits a diurnal variation in the adult, it is possible that the ontogeny of such a rhythm provides important information for the timing of puberty. To begin to evaluate this hypothesis, we determined the development of the diurnal leptin secretion in the rat. The young females were raised in a light-controlled environment (12L, 0700 h light on). A cannula was placed in the right atrium on the previous day, and blood samples were collected every 4 h on Days 21, 24, 28, 32, 36 (1 day after vaginal opening), and 48 (adult, diestrus of estrous cycle). In addition to vaginal opening, plasma prolactin levels were determined as an endocrine index of puberty. Changes in food intake were monitored because nocturnal food intake has been considered to be a synchronizer for the leptin rhythm. This pattern of food intake was clearly evident throughout the ages studied. By contrast, there was no leptin rhythm at 21 and 24 days of age. Beginning at 28 days, leptin secretion exhibited a significant nocturnal peak (2300 h); this nocturnal peak increased in amplitude at 32 and 36 days and was still apparent in the cycling adult at Day 48. Plasma prolactin did not exhibit a diurnal rhythm but it increased from Days 32 to 48. The present findings indicate that in the rat, both the appearance of the nocturnal leptin rhythm and the nocturnal increase in circulating leptin levels during development carry information for timing the onset of puberty.

Aging↗

PubMed1985

Changes in circadian rhythm and suppression of the plasma cortisol level after prolonged stress in the sheep.

Diurnal variations in the plasma cortisol level were studied in anoestrous, pro-oestrous and pregnant ewes subjected to weak electric stimulation of the fore-limbs 9 h daily for 3 consecutive days. In non-pregnant ewes the cortisol level rose on each of the 3 days when the stimulation was applied and then decreased on the day following the stimulation. A similar decrease in plasma cortisol concentrations in pregnant ewes appeared on the second day of footshocking. The acrophase of the circadian rhythm on electrostimulation days was synchronous with the time of application of footshocks; therefore, in stimulated ewes it was significantly accelerated compared to the prestimulatory day. A decrease in the plasma cortisol level in pro-oestrous and pregnant ewes was accompanied by disappearance of its normal rhythmicity. Since a normal plasma cortisol response to exogenous corticotrophin was noted after 3 days of footshocking it seems unlikely that the decrease in the cortisol level after prolonged stress was caused by exhaustion of the adrenal cortex. Some central mechanisms which could account for the biphasic changes in the plasma cortisol level and for disturbances of the hormone diurnal rhythmicity under conditions of prolonged stress are discussed.

Animals↗

PubMed1975

Transitory changes in plasma progestins, estradiol, and luteinizing hormone approaching ovulation in the bovine.

Progestins, estradiol, and luteinizing hormone were measured by radioimmunoassay in bovine plasma samples collected from indwelling jugular catheters daily on days minus 6 to minus 4, every 6 h on days minus 3 and minus 2, and every 2 h from day minus 1 to ovulation. Least squares analyses characterized time trends within animals and interrelationships between these hormones. Plasma progestins decreased from 5.7 ng/ml at day minus 6 to .07 ng at the peak of luteinizing hormone. No preovulatory peripheral increase in plasma progestins was detected. Estradiol increased from 2 pg/ml at day minus 4 to 6 pg at minus 12 h and then increased abruptly to 7.4 pg at the peak of luteinizing hormone. This matter increase in estradiol was synchronous with the acute preovulatory surge of luteinizing hormone. Association was positive between estradiol and luteinizing hormone, but negative between progestins and estradiol. Estradiol decreased 50% by 5 h following the peak of luteinizing hormone with a return to base (2 pg) at 14 h. An increase of .1 ng luteinizing hormone/ml plasma per day was linear from day minus 6 to 8 h prior to the luteinizing hormone peak. Luteinizing hormone increased to a peak of 13.5 ng/ml and remained elevated for 10.5 h. These results are consistent with the hypothesis that an increase at proestrus in estradiol rather than progestins triggers the preovulatory surge of luteinizing hormone in the bovine.

Animals↗

PubMed1982

Vaginal flora. A dynamic ecosystem.

The understanding of the dynamics of the genital flora in humans is not yet complete. Of the many extrinsic factors that influence the susceptibility of the female genital tract to colonization by bacteria, sex-hormone secretion is considered of prime importance. Hence the knowledge of any cyclic change in the microbial flora could help in reducing postoperative infections by enabling the surgeon to synchronize the surgery with the phase of minimal growth. The aim of this study was to determine the relationship, if any, of bacterial growth in the vagina and hormonal status. To study the bacterial flora and hormonal status, vaginal swab and serial colpocytology were done on five occasions at intervals of four days. Of 89 women studied, 54 were regularly menstruating, 22 had irregular cycles, and 13 were postmenopausal. An endometrial biopsy was done in all cases on the last day of the smears. The swabs were cultured for the presence of aerobic and anaerobic flora. The smears were stained by the Papanicolaou method to evaluate the hormonal status. The results indicated that there was no correlation between the hormonal status and the growth of bacteria.

Adult↗

PubMed1984

Plasma LH concentrations in the ewe in response to repeated injections of low doses of gonadotrophin releasing hormone during the follicular phase of the oestrous cycle.

Oestrus was synchronized in 15 naturally cyclic ewes by the administration of a prostaglandin F2 alpha analogue. Groups of five ewes were then treated i.v. with either small doses of gonadotrophin releasing hormone (GnRH; 125 or 250 ng/injection) or saline, at 2-h intervals from day 14 of the subsequent cycle until 24 h after the onset of oestrus. Treatment with GnRH induced episodic LH release which continued until the onset of a preovulatory LH surge. Mean plasma LH concentrations over this period were significantly (P less than 0.001) higher in animals receiving 250 ng GnRH (2.44 +/- 0.11 microgram/1) than in those receiving either 125 ng GnRH (1.17 +/- 0.06 microgram/1) or saline (1.14 +/- 0.05 microgram/1). However, GnRH treatment did not influence the timing of oestrus or mean ovulation rates.

Animals↗

PubMed1994

Ovarian surface epithelium during ovulatory and anovulatory ovine estrous cycles.

BACKGROUND: Ovarian surface epithelial cells have been implicated in the mechanisms of ovulation and development of common ovarian cancers. An early indication of predisposition to neoplasia is the formation of ovarian epithelial inclusion cysts. It was unclear whether morphological alterations along the ovarian surface are related directly to ovulation per se or associated endocrine parameters of reproductive cyclicity. METHODS: Light microscopic disturbances in ovarian surface epithelium were monitored during synchronous ovulatory and anovulatory estrous cycles of sheep. Ovulation blockade accompanied by normal luteal phases was induced by administration of indomethacin, a prostaglandin synthase inhibitor. RESULTS: Degenerative cells were sloughed from the apical dome of periovulatory follicles. The resultant stigma of luteinizing follicles was void of surface epithelium. Repair of the ovulatory wound by epithelium did not occur until complete involution of the corpus luteum during the subsequent estrous cycle. In a few cases inclusions containing entrapped ovarian surface epithelium were noted within adjacent stroma. Epithelia covering luteinized unruptured follicles remained intact and was not incorporated into the ovary during luteal resorption. CONCLUSION: Localized damage to and subsequent remodelling of the ovarian surface occurs in a cyclic fashion conjoined with the physical process of follicular rupture.

Animals↗

PubMed1987

Bactericidal activity of peripheral blood neutrophils during the oestrous cycle and early pregnancy in the mare.

The oestrous cycles of 20 mixed-breed mares were synchronized with daily injections of 10 mg oestradiol-17 beta and 150 mg progesterone given i.m. for 10 days. On the 10th day, 10-15 mg prostaglandin F-2 alpha was administered i.m. to induce oestrus. Neutrophils were isolated from jugular blood on the 2nd or 3rd day of oestrus, Days 5 and 7 after ovulation or during early pregnancy (Days 18-34 of pregnancy). Neutrophils were challenged with Staphylococcus aureus and their bactericidal activity examined after 30 and 120 min of incubation for a reduction of colony forming units. Bactericidal activity increased with the time of incubation (P less than 0.01) but did not differ for the oestrous cycle or pregnancy (P greater than 0.05).

Animals↗

PubMed1997

Some effects of adding p-LH in defined amounts to purified p-FSH to modify FSH/LH ratios during the superovulatory treatment of anestrous ewes.

Nonlactating Leccese ewes (n = 61) were used during seasonal anestrus to investigate the effects on ovarian response and embryo production of adding defined amounts of p-LH to purified p-FSH as well as decreasing the FSH/LH ratio during treatment. The ewes were synchronized with FGA-impregnated intravaginal pessaries for 9 days and prostaglandin F2 alpha (Cloprostenol) injected on the seventh day. They were divided into six treatment groups in a 3 x 2 factorial design: three amounts of purified p-LH (100, 50 or 25% equivalent to 525, 262 or 131 IU p-LH) x 2 regimen of p-FSH and p-LH administration (constant or decreasing FSH/LH ratio). Each ewe received a total of 525 IU p-FSH at a decreasing dose, twice daily over a 3-day period. Group I (n = 11), Group II (n = 10) and Group III (n = 10) were treated with p-FSH supplemented with p-LH at 100%, 50% and 25%, respectively, of p-FSH dose and a constant FSH/LH ratio throughout the treatment period. Group IV (n = 10), Group V (n = 10) and Group VI (n = 10) were treated with p-FSH supplemented with p-LH at 100%, 50% and 25%, respectively, of p-FSH dose but with a decreasing FSH/LH ratio over the 3 days of the treatment: 1.7-0.86-0.43 for Group IV; 3.4-1.7-0.86 for Group V; 6-3-1.5 for Group VI. Embryos were flushed surgically on Day 6 after estrus. The ovulation rate did not differ among the groups (8-12.8). Superovulation with 100% p-LH and decreasing the FSH/LH ratio (Group IV) resulted in: (i) the highest ova recovery (9.8 +/- 1.7), and this was significantly different (P < 0.05) from the 25% p-LH treated group (Group VI; 5.0 +/- 1.7), (ii) the highest fertilization rate (90.6 +/- 9.2%), with a significant (P < 0.01) difference compared with the constant ratio regimen (Group I; 62.6 +/- 8.3%); (iii) the highest transferable embryo yield (6.4 +/- 1.1), differing significantly (P < 0.01) from Group VI (2.2 +/- 1.1) and Group I (2.7 +/- 1.0). It is concluded that decreasing the amount of p-LH added to purified p-FSH did not improve the superovulatory response of ewes during the anestrous period. Transferable embryo production was significantly improved when ewes were treated with p-LH equivalent to 100% p-FSH, with the FSH/LH ratio decreasing during treatment.

Anestrus↗

PubMed1999

The concentration of faecal progestins during the oestrous cycle in Nkone cows and the effect of duration of storage of faecal samples at room temperature on faecal progestin levels.

The objectives of this study were to determine whether ovarian function in Nkone cows could be monitored by measuring progestin concentrations in faeces and to assess the effect of duration of storage at room temperature on faecal progestin concentrations. Faecal and blood samples were obtained once a day for 26 days from 21 Nkone cows whose oestrous cycles had been synchronized. Faecal samples from each cow were divided into five portions that were kept at room temperature for 0, 6, 12, 24 and 48 h, respectively, and then frozen. After centrifuging the blood to recover plasma and extracting steroids from the faeces, analysis of progesterone (P4) was carried out using solid-phase radioimmunoassay. The faecal progestin and plasma progesterone profiles corresponded well and were positively correlated (r = 0.70, p < 0.01). Faecal progestin concentrations decreased with increasing duration of storage at room temperature during both the follicular and luteal phases (p < 0.01). In both cases, the decline in faecal progestin concentrations followed an exponential pattern. The progestin concentrations in faeces after 48 h of storage at room temperature were higher (p < 0.05) during the peak luteal phase than in the follicular phase.

Animals↗