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1.
Abstract

Plasma prolactin secretion during the luteal phase and pregnancy was studied in 11 mated but non-parturient and 26 parturient blue fox vixens. Prolactin was measured in blood plasma once or twice a week using a heterologous double-antibody radioimmunoassay. Data for all females were fitted with an animal model. In both groups of females, prolactin concentrations increased slowly during the early post mating period. For the parturient vixens the prolactin values increased further until parturition, whereas there was only a slight increase in the non-parturient vixens. Statistically significant differences (p < 0.05) were observed in prolactin release between the non-parturient and parturient animals from day 36 after mating. A possible role of prolactin may exist in the luteotrophic complex maintaining pregnancy in blue fox vixens, because higher levels of plasma prolactin and progesterone appeared in the parturient vixens compared to the non-parturient during the second half of gestation.  相似文献   

2.
The uterine acetylcholinesterase and total cholinesterase (acetylcholinesterase plus butyrylcholinesterase) activities in normal and fenchlorphos treated blue fox vixens were determined during various reproductive states.AChE and Total-ChE of non-medicated vixens in oestrus were about one half of those in anoestrus. In pregnant uteri (luteal phase) the activities were 25 % and 30% compared to anoestrus.In vixens given 100 mg/kg fenchlorphos for 3 weeks during anoestrus, the remaining activity of AChE in uterus were in average 37%. Pregnant and non-pregnant vixens in the luteal phase medicated prior to mating and during time of implantation, displayed AChE activities which were only moderabely reduced (remaining activities 83% and 72% compared to medicated animals in anoestrus: remaining activity 37%).Plasma ChE-activity increased during pregnancy in the controls while enzyme activity was strongly reduced in animals given 100 mg/kg fenchlorphos daily through the whole pregnancy.It was concluded that the previous reported embryotoxic effect of fenchlorphos in the blue fox did not seem to be directed towards the moderate inhibition of the uterine cholinesterases.  相似文献   

3.
Red foxes ( Vulpes vulpes ) are a major pest species in Europe and Australia. Traditional methods of control such as hunting or poisoning are no longer sufficient or feasible. As with domestic dogs and cats, prolactin (PRL) in the vixen is an essential luteotropin during the second half of gestation. Hence, PRL inhibitors such as cabergoline have been used to induce abortions. Eighteen mated silver fox vixens (three groups of six foxes each) were treated orally with a placebo of paraffin oil (I), or with 15  μ g/kg cabergoline in feed once (II) or twice (III), on day 30 (I and II) or days 30 and 32 (III) post-coitum. Blood samples were taken prior to and after treatments and concentrations of PRL and progesterone (P4) were determined. Normal parturitions were observed in five of six, five of six and two of six vixens in groups I, II and III, respectively. In group III plasma concentrations of PRL and P4 decreased significantly but only temporarily. This drop in hormone concentrations was more pronounced in the vixens that did not carry to term. In conclusion, doses in excess of 15  μ g/kg of cabergoline are likely to prevent the development of fetuses to term in pregnant vixens.  相似文献   

4.
The possible effect of fenchlorphos, 0-0-dimethy1-0-(2.4.5-trichlorophenyl) phosphorothioate, upon the reproductive endocrinology in blue foxes (Alopex lagopus) was investigated. Five females were administered fenchlorphos orally at a dose of 100 mg/kg daily from 10 days before oestrus and up to the 21st day of gestation. This dose represents the therapeutic dose for the treatment of sarcoptic mange. Blood samples were collected for the analyses of progesterone, oestradiol-17β and luteinizing hormone (LH) in plasma. The vixens were ovario-hysterectomized on day 23, except 1 animal in the control group which was operated on day 17. Additionally, sperm quality and mating performance in 3 male blue foxes, which were administered 100 mg/kg fenchlorphos daily during the first 3 weeks of the mating season, were examined.Pregnancy was recorded in 2 medicated and 4 control animals. No pathological changes were observed in the uterus and the ovaries. The plasma concentrations of the hormones were similar to those obtained from the control group. No evidence of any disturbances concerning spermatogenesis in the males was observed. However, their libido appeared to be reduced. None of the males achieved a mating during and after the period of medication.  相似文献   

5.
Pathogenesis of blue fox parvovirus on blue fox kits and pregnant vixens   总被引：2，自引：0，他引：2  
To study the pathogenicity of a newly isolated parvovirus of blue fox (Alopex lagopus), pregnant vixens and 43 kits of different ages were experimentally infected with the agent. The kits had no clinical signs of disease, even though most of them excreted virus in their feces, and they responded immunologically to viral exposure. Infection during pregnancy appeared to affect the fetuses. A group of 15 blue fox vixens inoculated with the virus produced a statistically smaller number of kits (78) than did 15 untreated controls (131). Vaccination with a homologous inactivated virus preparation appeared to afford protection against reproductive losses. After infection, 15 vaccinated vixens gave birth to 97 kits, compared with 54 kits born to a similar, non-vaccinated experimental group.  相似文献   

6.
This study aims at determining both the accuracy and the rate of heat detection together with the so-called post-insemination anoestrus incidence in four Moroccan dairy herds under natural or semi-hand mating insemination. 369 females (cows and heifers) were involved from 4 large dairy units in which a herd fertility survey took place on a weekly basis. Heat detection was performed several times a day by the herdsman. Blood was sampled for plasma progesterone (P) determination on the oestrus and the mating day, on day 12 later as well as on day 21 after mating. Accuracy (A) was defined as the ratio of correct oestrus on detected oestrus during the mating days. Heat detection rate (R) was defined as the ratio of oestrus detected on oestrus expected, according to the P values 21 days after mating when the females were confirmed to be cycling. Post-insemination incidence was the complementary ratio to the latter. In the Moroccan dairy unit conditions, A = 91 p. 100, and R = 49 p. 100, the post-insemination anoestrus incidence was therefore just over 50 per cent. The distribution of the non-in-heat but mated females (9 per cent) allows two roughly equal sub-populations to be distinguished: those mated in mid-luteal phase and those with a 1-2 day overlap between the follicular phase and the oestrus. Finally the high incidence of post-insemination anoestrus demonstrates the inadequacy of heat detection for pregnancy diagnosis even under natural or semi-hand mating conditions.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

7.
Nine of 10 mature blue fox vixens (Alopex lagopus) in spontaneous oestrus ovulated approximately 2 days after the preovulatory increase in luteinizing hormone (LH). Plasma concentrations of follicle-stimulating hormone and progesterone increased simultaneously with the LH peak, whereas oestradiol-17 beta peaked 1 day previously. In the tenth vixen, an LH peak was not observed, and neither visible follicles nor corpora lutea were found in the ovaries 6 days after peak vaginal electrical resistance. Eggs were ovulated as primary oocytes, but oocyte maturation was initiated within the day of ovulation (2 days after the LH peak). Within the next 2 days (3-4 days after the LH peak) the first polar body was extruded, and the cumulus mass was completely dissociated from the zona pellucida. The interval between the preovulatory LH peak and initiation of the final oocyte maturation is thus considerably longer in the blue fox than for example in the cow (48-72 h compared with 9-12 h). This suggests that the relationship between these two events is somewhat different in the blue fox.  相似文献   

8.
Aims: To determine the reproductive performance of cows diagnosed as anoestrus prior to the planned start of mating (PSM) when they were either treated when first diagnosed, or left untreated until 16 days after the PSM.

Methods: A clinical trial was conducted during the 1996/97 and 1997/98 breeding seasons involving 823 anoestrous dairy cows in 14 herds. On Day-8 (PSM = Day 0), cows in one group (Treated) were each treated with an intravaginal device containing 1.9 g of progesterone (CIDR).The CIDR device was removed on Day-2, and on Day-1 each cow was injected intramuscularly with 1 mg oestradiol benzoate. Cows in the second group (Control) remained untreated at the time of first examination. All cows detected in oestrus after the PSM were mated by artificial insemination (AI) or a bull. Sixteen days after the PSM, all cows that had not been mated were presented for veterinary examination, and those which were still classified as anoestrus were treated with the previously described CIDR regimen. Pregnancy status and approximate date of conception were determined by palpation per rectum 10-13 weeks after the PSM or 6 weeks after the end of the mating period.

Results: Treatment of anoestrous cows 8 days before the PSM significantly increased the number of cows detected in oestrus (95.0% vs 63.1%;p < 0.001) and conceiving (59.5% vs 38.8%;p < 0.001) during the first 21 days of mating, and reduced the interval from PSM to conception by 7.5 days (p < 0.001). There was no significant difference between the conception rate of cows mated following the CIDR treatment regimen compared to cows mated at their first spontaneous oestrus after calving (52.4% vs 58.3%; p = 0.143).

Conclusion: Diagnosis and treatment of anoestrous dairy cows prior to the start of mating significantly improves their reproductive performance under the seasonal mating conditions typical of spring-calving New Zealand dairy herds.  相似文献   

9.
There is no safe and accurate method for early termination of pregnancy in the rabbit. So this study was carried out to determine the effect of aglepristone administration in preventing early pregnancy before implantation in this species. Twenty‐two animals (10–12 months old, New Zealand White rabbits) were naturally mated and pregnancies were confirmed in all animals by ultrasonographic examinations on day 6 after mating (5–7.5 MHz linear array transducer Dynamic Imaging Sonostar, UK) and the animals were grouped randomly: Group I & Group III: Aglepristone (Alizin®, Virbac; 10 mg/kg, subcutaneously) was injected twice, 24 h apart, on days 6 and 7 after mating (n = 5; n = 8). Group II & Group IV: The same volume of 0.9% NaCl solution was subcutaneously injected in the same interval and served as controls (n = 5; n = 3). Ultrasonographical examination of the uterus was performed daily from day 7 to day 11 post‐mating to test aglepristone efficiency. Blood samples were collected between days 6 and 30, centrifuged at 3070 g for 10 min and stored at ?20°C. The does in aglepristone groups (Group I, III) were not pregnant whereas all animals in control groups were pregnant (Group II, IV). The does in group I & III were examined only clinically and ultrasonographically; however, does in groups III and IV were laparomized on days 6, 7, 9 and 11 post‐mating to control countable implantation sites. No implantation sites were present in group III whereas they were seen obviously in group IV. Side effects were not observed. The mean serum progesterone (P4) concentrations were not significantly different between control and treated does (p > 0.05). The results indicate that aglepristone treatment on days 6 and 7 after mating could prevent pregnancy after unwanted matings without any side effects in the rabbit. Aglepristone treatments are possibly not affecting further fertilities before implantation.  相似文献   

10.
Endometrial expression of oestrogen receptor‐α (ERα), progesterone receptor (PR) and cyclooxigenase‐2 (COX‐2) was evaluated in non‐pregnant and pregnant llamas during the period when luteolysis/maternal recognition of pregnancy is expected to occur. Females (n = 28) were divided into two groups: non‐pregnant llamas were induced to ovulate with a Buserelin injection, and endometrial biopsies were obtained on day 8 (n = 5) or 12 (n = 5) post‐induction of ovulation. Animals of the pregnant group (n = 18) were mated with a fertile male. Pregnancy was confirmed by the visualization of the embryo collected by transcervical flushing in 5 of 9 animals on day 8 post‐mating and by progesterone profile on day 12 post‐mating in 4 of 9 animals, when endometrial biopsies were obtained. An immunohistochemical technique was used to evaluate receptors population and COX‐2 expression. Pregnant llamas showed a higher percentage of positive cells and stronger intensity for ERα than for non‐pregnant llamas in stroma on day 8 and in the luminal epithelium on day 12 post‐induction of ovulation, while a deep decrease in endometrial PR population was reported in pregnant llamas on that day in luminal and glandular epithelia and stroma. In the luminal epithelium, COX‐2 expression was lower in pregnant than in non‐pregnant animals. Briefly, the increase of ERα in pregnant llamas gives further support to the hypothesis that oestrogens are involved in the mechanism of maternal recognition of pregnancy. Endometrial PR decrease in pregnant llamas might be a necessary event to allow the expression of proteins involved in conceptus attachment, a mechanism widely accepted in other species. Moreover, embryo seems to attenuate maternal PGF2α secretion during early pregnancy by decreasing the endometrial expression of COX‐2 in the luminal epithelium of pregnant llamas.  相似文献   

11.
The aim of this study was to determine whether blood plasma progesterone is a reliable indicator of pregnancy in mink at an early stage of gestation. We also attempted to establish the threshold value of progesterone as a pregnancy indicator. The analysis was carried out at a production farm on 42 standard female mink aged 1 year, which were grouped both according to the observed success of mating ("mated" and "unmated") and the level of blood serum progesterone measured afterwards ("pregnant" and "nonpregnant"). It was next verified whether a particular female had been assigned to the proper group in the first place. An analysis of accuracy of mating success assessment within the group of unmated females revealed that more than one-third of decisions were wrong, since some females that had been considered unmated ultimately whelped. This suggests that mating supervision by farm workers lacks reliability. A progesterone test for verification of such management decisions should limit the risk of err,or. We suggest that progesterone tests could be carried out using the threshold values 1.9 ng/ml and 20 ng/ml in blood sampled on 25 March and 8 April, respectively, although some level of uncertainty should be taken into account.  相似文献   

12.
The objective of this experiment was to examine the effects of feeding a vitamin A deficient diet (VAF) to pigs at different times on day 100 of foetal and days 0, 1 and 2 of neonatal development. Three treatments included a control (n = 12), VAF for 100 days before mating and during the first month of pregnancy (n = 13; VAF–control), and VAF during the oestrous cycle before mating and throughout pregnancy (n = 13; control–VAF). On day 100 of pregnancy, maternal liver and plasma retinol concentrations were reduced in both groups of gilts fed a vitamin A free diet compared to controls (P < 0.001 and P < 0.01, respectively). Day 100 foetal liver retinol concentrations were not affected by dietary treatment, whereas foetal plasma concentrations were higher in foetuses carried by gilts fed the VAF–control diet (P < 0.05). Piglets born to mothers fed the control–VAF, but not the VAF–control diet had consistently lower hepatic and plasma liver retinol concentrations (P < 0.05). Moderate reductions in maternal vitamin A at either stage of pregnancy did not affect pregnancy rate, litter size, progesterone secretion or the allometric relationships between foetal or neonatal organ and total body size. Reduced vitamin A during conception and early pregnancy, but not during later pregnancy, was associated with increased within-litter uniformity in birth weight (P < 0.05) and a tendency for fewer low birth weight piglets, but this needs to be confirmed in a greater number of sows. The mechanism underlying this effect is not known, but appears to not involve an alteration in progesterone production.  相似文献   

13.
AIM: To determine whether short-term progesterone supplementation post mating or shearing of ewes in early pregnancy affected either the proportion of ewes that lambed or that had multiple lambs, or the birthweight of lambs.

METHODS: Romney ewes (n=457) were synchronised in oestrus using controlled internal drug-releasing (CIDR) devices containing progesterone, and mated to Romney rams over a 5-day period. The mid-point of mating (Day 0) occurred 2 days after the withdrawal of CIDR devices. Ewes mated (n=397) were randomly allocated to one of four treatment groups: shearing at Day 5, shearing at Day 30, no shearing, and no shearing plus progesterone supplementation using a CIDR device inserted on Day 3 for 6 days. During the period from Day 5 to Day 27, six harnessed Suffolk rams were placed with the ewes and matings recorded. At Day 48, all ewes that did not return to the Suffolk rams were scanned for pregnancy using ultrasound. At Day 140, single- and multiple-bearing ewes were set-stocked at 15.1 and 12.2 ewes/ha, respectively, and equivalent numbers of ewes from each treatment group were placed in each paddock. Blood samples from 10 unshorn and 10 progesterone-supplemented ewes were collected on Days 3, 6 and 9, and analysed for plasma progesterone concentrations. Lambs were identified to their dam and weighed within 12 h of birth, and again at 27 and 93 days after the mid-point of lambing. The ewes were weighed at regular intervals throughout the trial.

RESULTS: Plasma progesterone concentrations of supplemented ewes were higher than those of unsupplemented ewes (3.28 vs 1.75 ng/ml) on Day 6 (p=0.02) but not on Day 9 (4.58 vs 4.63 ng/ml). Treatment of ewes had no effect on either the proportion of ewes which lambed to the synchronised mating period or that had multiple lambs. Lambs born to ewes shorn at Day 30 tended (p=0.09) to be heavier at birth (by 0.28 kg) than those born to unshorn ewes but this effect was not evident when data were corrected for length of gestation. Neither shearing at Day 5 nor progesterone supplementation had any effect on the birthweight of lambs, and the treatment of ewes had no effect on the survival rate of lambs to weaning.

CONCLUSIONS: Progesterone supplementation for 6 days beginning 3 days post mating did not increase either the proportion of ewes that lambed or that had multiple lambs, or the birthweight of lambs. Shearing 5 days after mating had no significant effect on the reproductive performance of ewes and need not be avoided, but is unlikely to result in an increase in lamb birthweight. Shearing ewes at Day 30 may result in an increase in the birthweight of lambs but, ideally, ewes should be further advanced in pregnancy before shearing is undertaken.  相似文献   

14.
Termination of mid-term pregnancy in the dog with oral RU 486   总被引：2，自引：1，他引：1  
A total of four pregnancies were terminated in three bitches (two beagles and one flatcoated retriever) with a single dose of 20 mg/kg (one case), two doses of 8-3 mg/kg (one case) or 20 mg/kg plus 40 mg/kg (two cases) RU 486 by mouth (Mifepristone; Roussel-Uclaf, France) from day 26 to day 36 after the first day of mating of the bitch. Abortions occurred within two, four, 11 and 11 days after the initial treatment, respectively. The clinical status of the bitches was similar to that observed during a normal parturition, ie, lowering of the body temperature, shivering, panting and nesting behaviour. No side effects were seen. The beagle bitch that aborted twice, was mated at the first oestrus after the first abortion, conceived and aborted the same number of puppies the second time. The peripheral plasma progesterone concentration at the time of treatment in all bitches was < 75 nmol/litre. It had decreased to between 24-2 and 13-1 nmol/litre at the time of abortion and to between 4-0 to 0–5 nmol/litre at four to 15 days after the initial treatment. Peripheral plasma levels of prolactin increased three- to fourfold within 24 to 48 hours after treatment, concomitant with the drop in progesterone and had returned to basal levels within two to three days. Prolactin concentrations also increased around the time of intrauterine fetal death. Prostaglandin F2aα-metabolite concentrations increased slowly after treatment, and around the time of abortion the levels increased five- to 10-fold. RU 486 seems to be a safe and effective abortifacient for use during mid-term pregnancy in the dog.  相似文献   

15.
The aim of the present study was to investigate the effect of breeding season [late spring (LSP) vs winter (WIN)] on reproductive performances, foetal development and progesterone (P4) concentrations of sheep in the subtropics. Ewes of Farafra breed were exposed for mating in LSP (n = 79) and WIN (n = 45). Ultrasonographic examinations were performed at days 25, 45 and 75 of mating to estimate the pregnancy rate, incidence of twinning and percentage of foetal losses. Foetal growth rate was determined at 10‐day interval, and blood samples were taken on days 0 (oestrus), 8, 18 of oestrous cycle and on days 30, 45, 60 and 90 of pregnancy for P4 analysis. The results showed that pregnancy and lambing rates were greater (p < 0.01) for ewes mated in LSP (93.7% and 92.4%) than for those mated in WIN (75.6% and 71.1%), respectively. There was no effect of season on the incidence of twinning (overall 19.1%) or the frequency of foetal losses (overall 7.3%). Transient reduction of placental size, foetal growth and P4 concentration was observed following LSP matings. In conclusion, pregnancy and lambing rates were higher following LSP matings. Summer heat stress of the late spring mated ewes transiently interferes with foetal growth and P4 concentrations.  相似文献   

16.
The persistence of maternal antibodies transfer from rabies-immune vixens to their fox cubs was studied. Eight vixens (Vulpes vulpes) were vaccinated 1 month before pregnancy with Lysvulpen vaccine for oral vaccination of foxes. Twenty-one were foxes born at the first half of April. The geometrical mean titre of rabies neutralizing antibodies of fox cubs sampled in May was 1.31 IU/ml and has dropped successively to 0.54 IU/ml in June samples and to 0.18 IU/ml in July samples. It has been proven that the duration of rabies maternal antibodies in fox cubs was limited to 2 months after birth.  相似文献   

17.
ABSTRACT

Eighteen beef cows with their calves were assigned to 3 groups considering body conditions scores at calving (BCSC): T1 (high BCSC, maintained throughout the study); T2 (low BCSC, increased during the study); and T3 (low BCSC, maintained throughout). An estrus synchronization protocol was implemented, with fixed time artificial insemination on day 70. Follicular or luteal growth, and pregnancy rate were similar between groups. Of all cows, five showed multiple ovulations (2–6); increasing number of ovulations reduced preovulatory follicle diameter and individual luteal volume (P?<?0.05), but total luteal volume was greater in cows with 2 or 3 ovulations on day 14 after insemination (P?<?0.05). Estradiol and progesterone levels were associated to follicular and luteal growth, respectively. No difference was found in IGF1 or GDF9 levels between groups or associated to fertility. No association was found between BCS, IGF1 or GDF9 levels and the reproductive process.  相似文献   

18.
This study was undertaken to detect pregnancy in Iraqi riverine buffalo (Bubalus bubalis) using three different methods (rectal palpation, plasma progesterone concentration and detection of the presence of pregnancy‐specific protein B (PSPB) with the BioPRYN® enzyme‐linked immunosorbent assay (ELISA) test. The aim of the study was to identify the most sensitive, early and accurate method for detecting pregnancy. Twenty‐two female riverine buffalo that were 6.0 ± 0.93 years old were used. Four blood samples per buffalo were taken via jugular venipuncture at days 22–24, 32–34, 42–44 and 58–61 post‐mating (PM) to measure the progesterone concentration (ng/ml) and to detect the presence of plasma PSPB. The rectal palpation method was employed to evaluate all buffalo on days 42–44 and 58–61 PM. The BioPRYN® test differed (p < 0.01) from the other tests with earlier accuracy for detecting pregnant and non‐pregnant buffalo. Eighty‐eight percent of pregnant and 76.9% of non‐pregnant buffalo were distinguished early (days 22–24 PM) using BioPRYN® and plasma PSPB‐ELISA level (2.09 ± 0.12 ng/ml) in relation to 66.7% and 53.9% detected using the progesterone assay at similar days (4.30 ± 0.40 ng/ml). In conclusion, these results described, for the first time, the early and accurate pregnancy detection of water riverine buffalo using BioPRYN® technology and provided the plasma levels of PSPB using an ELISA test. These findings will improve the reproductive and productive efficiency of Iraqi riverine buffalo by adapting the recent management and reproductive strategies in Iraq and in the world.  相似文献   

19.

A survey of 7122 dromedary camels in 115 herds in Saudi Arabia was used to estimate the effects of herd size (HZ; <?25 vs. 25–49 vs. 50–100 vs. >?100 camels), herder/camels ratio (H/C; 1:<?25 vs. 1:25–50 vs. 1:>?50), manager experience (ME; <?5 vs. 5–10 vs. >?10 years), male/females ratio (M/F), housing system (HS; free vs. closed vs. mixed), length of the breeding season (winter vs. winter and spring vs. fall, winter and spring), age at first mating (3 vs. >?3 years), and time of mating after parturition (≤?3 vs. >?3 months) and their interactions on the overall pregnancy rate. Barren females of these herds (n?=?886) were examined for the causes of infertility. Results showed that herds with H/C of 1:<?25 had higher overall pregnancy rate (95.29%) than herds with H/C of 1:25–50 (79.84%) and those with H/C of 1:>?50 (72.79%) (p?=?0.003). Herds having ME of >?10 years revealed greater overall pregnancy rate (94.89%) than herds with ME of 5–10 years (80.54%) and those with ME of <?5 years (72.5%) (p?=?0.001). There were significant interactions between H/C × HZ (p?=?0.003), H/C × HS (p?=?0.006), and ME × HS (p?=?0.02). The overall pregnancy rate did not significantly differ between herds bred females by age of 3 years and those bred females by age >?3 years and in females bred within 3 months after parturition and in those bred after 3 months. The mean calving interval was shorter (p?=?0.008) in camels mated within 3 months of parturition (15.25?±?2.8 months) than in those mated after that time (24.33?±?6.5 months). Clinical endometritis, ovarian hydrobursitis, and vaginal adhesions were the common clinical findings in barren females. Thus, efforts to reduce the age at first mating and the interval after calving, increase the number of herders/camels, and control reproductive disorders could improve the reproductive performance and quality of camel herds in Saudi Arabia.

  相似文献   

20.
Despite efforts undertaken to conserve the endangered European mink, its reproduction is still poorly studied. The aim was to study its reproductive cyclicity, faecal progesterone concentration and ovarian changes during early pregnancy, with the emphasis on the pre-implantation period and implantation. During the 2004 breeding season, oestrous cycle was monitored in 39 females as well as ovarian changes during early pregnancy in 22 females. During the 2007 breeding season, faecal progesterone concentration measured by radioimmunoassay was monitored during pregnancy in 10 females throughout their pregnancy. The breeding season 2004 started on March 18 and ended on May 10, with the peak recorded in April. The duration of first oestrus was 1–12 days. If not mated, the vast majority of females entered second oestrus after 12–55 days. In general, relatively low faecal progesterone values were detected in European mink; an average of 42.69 ± 4.70 ng/g faeces in oestrous females with a maximum of 176.44 ± 23.01 ng/g faeces on pregnancy day 12. anova indicated a significant effect of the pregnancy stage. Post hoc comparisons with Fisher least significant difference (LSD) test revealed that faecal progesterone concentrations on days 8 and 12 post coitum (p.c.), but not at the end of pregnancy (day 40), were higher when compared with the initial oestrous level. Implantation in this species occurs on day 12 p.c. and was indicated by prominent uterine swellings and failure to flush the uterine horns beyond this day. Advanced luteogenesis was observed with prominent corpora lutea found in ovaries around the time of implantation. To conclude, European mink is a seasonally polyoestrous species; the early pregnancy of European mink resembles that of European polecat, i.e. in both species, implantation occurs on day 12 p.c. without any implantation delay.  相似文献   

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