Domestic queens under natural temperate photoperiod do not manifest seasonal anestrus

Domestic cat seasonality between the tropics and the arctic zones is scarcely described and results are inconsistent. The aim of this study was to describe domestic feline seasonal patterns under a natural temperate photoperiod. A total of 372 estrous cycles were studied in 34 post pubertal cats during 900 days. The queens were housed in a cat colony (31°25' South Latitude, 64°11' West Longitude), acclimated under natural photoperiod and daily observed for reproductive behavior. Vaginal cytology was conducted three times a week. For each cat the number of estrous cycles and days in estrus per month for each year were recorded. The months of the year were grouped in four periods of 3 months each according to day length and photoperiod. Comparisons of estrous days among periods were performed by ANOVA for repeated measures. All the cats had estrous cycles throughout the year without intervals of anestrus. Mean number of estrous days differed among the periods (P<0.01), those of long day length and ascending photoperiod being greater (12.5±0.6) to those of descending photoperiod either with long (8.9±0.7) or short (9.3±0.7) days. When the two periods with ascending day lengths were merged and compared to the two periods with descending day lengths merged, the number of estrous days were greater when day length ascended (P<0.01). Nearly 60% of the estrous cycles occurred during the periods of ascending day length. It is concluded, that domestic cats under natural temperate photoperiod have estrous cycles throughout the year showing peak activity the months with increasing photoperiod.     

Occurrence of flehmen in male buffaloes (Bubalus bubalis) with special reference to estrus

Pheromonal cues present in the urine and vaginal mucus during the estrus period elicit courtship behaviour in mammals including the characteristic flehmen behaviour. In the present study, the flehmen behaviour was assessed in male buffaloes by exposing them to heifers for three consecutive estrous cycles. Behavioural observations revealed that the bulls sniffed the female's external genitalia, responded to the chemical signal(s) and exhibited the flehmen behaviour similar to those reported in other ungulates. The flehmen behaviour was recorded daily during 15-min contact with females for three consecutive estrous cycles. Out of 180 observations during five days estrus periods (-3 to +1 days) which included high frequency of flehmen behaviour and out of 637 observations with or without flehmen behaviour during diestrus periods, the bull displayed 365 and 441 flehmen behaviour, respectively. Average numbers of all (2.03 +/- 0.66) and repeated flehmen (1.05 +/- 0.64) behaviour during estrus periods were significantly higher than those of diestrus periods of all (0.69 +/- 0.25) and repeated flehmen (0.11 +/- 0.10). The statistical significance was higher (P < 0.001) in repeated flehmen behaviour of estrus as compared to that in diestrus. In case of all flehmen behaviour, the statistical significance was higher (P < 0.01) in estrus when compared to that in diestrus. The occurrence of flehmen behaviour in male buffaloes clearly indicates that the specific pheromonal compound(s) present in the urine/vaginal mucus during estrus significantly influence the flehmen behaviour.     

Photoperiod manipulation to increase the productivity of black‐footed ferrets (Mustela nigripes) and Siberian polecats (M. eversmanii)

The endangered black‐footed ferret (Mustela nigripes) reproduces naturally in the spring. The Black‐Footed Ferret Recovery Program would benefit from increased productivity in the captive population by manipulating photoperiod and temperature to create three artificial cycles in 1½ years. In the present study the photoperiod was set at 8 hr light:16 hr dark for 1–2 months, then switched to 16 hr light:8 hr dark for 4–5 months. The males' light was switched 1 month before the females' light. Three cycles were performed in 2 years. During the first cycle, 0% of the males bred, 17% of the females came into estrus and were bred through artificial insemination, and 0% of the females whelped. In the second cycle, 100% of the females came into estrus and were bred naturally, and 77% whelped. In the third cycle, all males showed testicular recrudescence but none bred; all females showed signs of estrus, 40% were bred using artificial insemination, and 0% whelped. Siberian polecats (Mustela eversmanii), the black‐footed ferrets' closest living relative, also were put on an artificial photoperiod, coinciding with the black‐footed ferrets' third cycle. All female polecats came into estrus and were bred naturally, and 33% whelped. All males showed testicular recrudescence, and 22% produced sperm and bred. The low rate of success in breeding and whelping suggests that multiple cues may be needed to induce estrus in ferrets and polecats. Zoo Biol 22:1–14, 2003. © 2003 Wiley‐Liss, Inc.     

Ovarian cycle of the captive formosan gem‐faced civets (Paguma larvata taivana)

Formosan gem‐faced civets are classified to be endemic sub‐species of Paguma larvata in Taiwan. Little about their reproductive physiology has been reported. This study was designed to characterize the ovarian activity throughout the year and define ovarian cycle length and the lengths of its component phases. Serum samples were collected for enzyme immunoassay (progesterone and estradiol) from seven captive civets twice weekly for 1 year. Meanwhile, periodic changes in external genitalia (vulva swelling) and vaginal cytology were examined and recorded. Results showed estrous cycles exhibited two types: 18‐day (18.5±1.1, n=64) and 28‐day (27.6±1.0, n=28) as shown by progesterone and estradiol fluctuations and corresponding changes in vulva morphology and vaginal cytology. Both types showed a similar 7‐day follicular phase, peaking progesterone at Day 7. The 18‐day cycle type prevails in the spring and summer whereas the 28‐day cycle type is significant in the autumn. In summary, female gem‐faced civets are polyestrous (approximately 13 cycles/year), and non‐typical seasonal breeders, with follicular phase and two distinct durations of luteal phases (diestrus) cycling throughout the year, but the frequency of ovarian cycles was remarkably gradually decreased from September to February of next year. Zoo Biol 0:1–11, 2007. © 2007 Wiley‐Liss, Inc.     

Vaginal pH during estrus in mares

Vaginal hydrogen ion concentration of Saddlebred mares was measured throughout the behavioral estrous period. The mean pH on the day of ovulation was significantly (P=<.01) lower than on all other tested days of estrus. Follicular development and vaginal pH values in pony mares at time of slaughter were highly correlated. A significant decrease in vaginal pH values, determined through a series of carefully monitored measurements during estrus, was found to be characteristic and indicative of ovulation.     

Characteristics of the estrous cycle of the swamp buffalo under temperate conditions

Estrous cycle, duration of estrus and time of ovulation of eight cyclic buffaloes were examined during a period of one year. Animals were kept under loose-housing conditions and fed according to the Japanese Feeding Standards for dairy cattle. All the animals were observed for the occurrence of estrus twice daily by using a vasectomized bull, and ovarian cycles of each animal were monitored by weekly rectal palpation. Duration of estrus and time of ovulation were determined in 32 estrous periods from eight animals. Animals came in estrus throughout the year. The estrous cycles corresponding to single ovarian cycles ranged from 11 to 38 days with a mode interval of 20 days, averaged 21.5 +/- 4.7 days. Percentage of the cycles within a range of a mean +/- 1 SD (17-26 days) was 79.2 %, whereas that of cycles shorter or longer than the expected range was 9.4 % and 11.4 %, respectively. Estrus took place regardless of the time of day and lasted 9 to 27 hr (19.9 +/- 4.4 hr). Ovulation occurred 6 to 21 hr (13.9 +/- 3.4 hr) after the end of estrus, with a mode interval of 12 hr. There were no significant seasonal variations in the estrus characteristics studied.     

Sexual characteristics of domestic queens kept in a natural equatorial photoperiod

The objective of this study was to describe the sexual characteristics of domestic queens kept under natural equatorial photoperiod conditions without mating. Estrous signs were detected in 25 pubertal queens by manual stimulation and by exposure to a tomcat twice daily for 6 months (January to June). The signs observed were tail deflection, spinal flexion, rubbing or rolling, vaginal discharge, vocalization, treading of the hind legs, body or tail tremor and rigidity, blow or scratches, and discomfort on manipulation. The queen was considered in estrous when neck grip, tail deflection and attempted penile intromission by the male were allowed after mounting. From 187 cycles, there were (mean +/- S.E.M.) 7.5 +/- 0.7 cycles detected per queen; the duration of the cycle, estrus and non-acceptance were 18.1 +/- 0.9, 7.9 +/- 0.5, and 10.3 +/- 0.9 d, respectively. Queens always maintained some signs of sexual behaviour; they remained ambivalent for no more than 24 h at a time. It was noted that 85.3% of the observations of body or tail tremor and rigidity were made during estrus; therefore, these signs were considered characteristic of sexual receptivity. There was no evidence of prolonged anestrus or of a circannual pattern to estrus cyclicity.     

Estrus induction in the bitch using a combination diethylstilbestrol and FSH-P

The purpose of the study was to induce estrus and ovulation in normal bitches using a combination of diethylstilbestrol (DES) and follicle stimulating hormone of porcine pituitary origin (FSH-P). Thirteen mature mongrel female dogs were divided into two groups, the first group was treated for estrus induction during late anestrus and the second group during mid-anestrus. The dogs were monitored by teasing, vaginal cytology, and hormonal assay during the induced (n = 13) and the previous spontaneous estrous cycle (n = 9). Six of eight and three of five bitches came into standing estrus in the first and second group, respectively. Of the bitches that came into estrus, three conceived in the first group and one in the second. The average induced litter size was 7.0 versus 7.5 for the colony. Based on vaginal cytology the induced proestrus and estrus lasted 1.7 (0 to 3) and 12.9 (4 to 24) d, respectively, while the spontaneous proestrus and estrus lasted 5.8 (0-17) and 12.8 (9-15) d, respectively. Progesterone profiles were similar between the induced and spontaneous estrous cycles, although the progesterone peak was higher during the spontaneous cycle. The preovulatory luteinizing hormone (LH) surge was observed in only one induced estrous cycle. Modest results were obtained with this therapy. However, the litter sizes were normal and the induced cycles were very similar to the physiologic ones. No side effects were seen with the oral form of DES.     

Estrous cycle of the tayra,Eira barbara

Thirty-three estrous cycles of three female tayras were defined using vaginal cytology and/or behavioral observations. Estrous cycles averaged 56.0 ± 4.73 and 52.2 ± 15.5 days in length for two young tayras and 93.9 ± 21.0 for an older female. The complete absence of parabasal cells in vaginal smears coincided with vulvar tumescence and was diagnostic of estrus.     

Effects of using vasectomized bulls in artificial insemination practice on the reproductive efficiency of Italian buffalo cows

The effects of the presence or absence of vasectomized male buffaloes on the reproductive efficiency of buffalo cows (n = 396) undergoing artificial insemination (AI) was studied on six farms owned and operated by a single consortium. Lactating animals were separated into two groups of various sizes on each farm and kept under semi-range conditions. Vasectomized bulls were present in one group at a bull/empty-cow ratio of 1:30. No bulls were present in the other group. Reproductive efficiency between the two groups over a period of 3.5 months was compared and evaluated on the basis of: 1) the number of spontaneous overt estruses associated with either feeble or intense signs of estrous behaviour; 2) the number of functional estrous cycles, i.e. estrous cycles with luteal phases defined as normal, based on specified progesterone concentrations in milk or blood plasma 8–10 days after estrus; 3) the number of consecutive functional estrous cycles in cases of induced estrus; and 4) pregnancy rate.Groups with bulls present demonstrated a significantly higher reproductive efficiency than groups without them. There was a higher incidence of spontaneous estrus (92 versus 69%; P < 0.01); spontaneous estrus of high intensity (62.2 versus 31.1%; P < 0.01); and higher incidence of functional estrous cycles following both spontaneous (65.8 versus 57.1%) and induced (77.0 versus 59.5%; P < 0.05) estrus. Exposure to vasectomised bulls also increased the incidence of consecutive functional estrous cycles (90.5 versus 68.1%; P < 0.01), and the pregnancy rate in cows inseminated at spontaneous (42.5 versus 18.9%; P < 0.01) or induced (51.1 versus 33.3%; P < 0.05) estrus. Overall pregnancy rate did not differ significantly between cows inseminated at induced or spontaneous estrus, although in the absence of bulls, pregnancy rate per AI was higher in cows inseminated at induced than at spontaneous estrus (33.3 versus 18.9%).     

The peripubertal golden hamster and the transition between daily and estrous cycle hormone rhythms

Transitional patterns of LH, FSH, and progesterone (P4) in the circulation were studied in peripubertal female golden hamsters. A daily rhythm, with afternoon surges of these hormones, is typical of the immature female, whereas 4-day rhythms characterize the estrous cycle of the adult. Blood samples were collected repeatedly from maturing individuals at either 1400 or 1700 h. Each animal was examined daily for the appearance of regular vaginal estrous cycles as indicated by a mucous exudate on the morning of ovulation. Between Days -10 and -5 relative to first vaginal estrus (FVE), afternoon surges of LH, FSH, and P4 were often observed. From Days -5 to -1 relative to FVE, afternoon surges of LH and FSH were less frequent, but P4 retained the daily rhythmicity until Day -2. A 4-day pattern of LH secretion, but not of FSH or P4, was established prior to FVE. To determine whether or not ovulations were occurring prior to the appearance of external vaginal estrous cycles, reproductive tracts were collected from 26-34 days of age and examined for evidence of ovulation. Of 124 females, concordance between the record of daily vaginal examinations and the examinations of the ovaries and oviducts was found in 103 cases (83%). The development of ovarian follicles was correlated with FVE in peripubertal hamsters by unilateral ovariectomy. Antral follicles were found only in the last 3 days prior to vaginal estrus.     

Relationship between opposite changes of vaginal and vestibular impedance during estrous cycle in sows

Several bioimpedance techniques have been developed for noninvasive monitoring of reproductive events occurring in cyclic gilts and sows. Our objective was to compare the changes of vaginal and vestibular impedance during the porcine estrous cycle (experiment 1). In addition, we examined the causes of impedance variations in the vaginal vestibule during periestrus (experiment 2). The vaginal and vestibular impedance were measured with specially designed instruments. Sows were monitored for estrus via exposure to a sexually mature boar. The impedance in the vagina decreased gradually after weaning (P<0.01) reaching its nadir 2 days before estrus and increased during estrus to near maximum 2 days after estrus onset (P<0.01). The vaginal impedance during diestrus reached approximately the same level as on the weaning day. In contrast, the impedance in the vaginal vestibule increased gradually after weaning, then markedly during estrus (P<0.01) reaching its maximum 2 days after the onset of estrus followed by an abrupt decrease during early diestrus (P<0.01). The vestibular impedance after early diestrus reached almost the same level as before estrus. A significant negative correlation was found between the vaginal impedance in proestrus and vestibular impedance in periestrus. In experiment 2, interaction of the interval from weaning to estrus and parity significantly influenced the vestibular impedance in periestrus. The breed of sows did not affect the impedance in the vaginal vestibule through the whole experiment. From the present study we conclude that closely related inverse changes of the vaginal and vestibular impedance take place in pigs during the estrous cycle.     

Reproductive steroid hormones and ovarian activity in felids of the Leopardus genus

Reproductive endocrine patterns were characterized in female ocelots (Leopardus pardalis; n = 3), tigrinas (Leopardus tigrinus; n = 2), and margays (Leopardus wiedii; n = 2) housed in captivity in southern Brazil. Females were maintained as singletons and exposed to natural fluctuations in photoperiod. Cyclic changes in ovarian steroids were monitored by analyzing estrogen and progestogen metabolites in fecal samples collected five times weekly for 14 to 18 months. Based on intervals between fecal estrogen peaks, mean (± SEM) duration of the estrous cycle was 18.4 ± 1.6 days for the ocelots (range, 7–31 days; n = 75 cycles), 16.7 ± 1.3 days for the tigrinas (range, 11–27 days; n = 23 cycles), and 17.6 ± 1.5 days for the margays (range, 11–25 days; n = 32 cycles). Fecal progestogen analyses combined with two laparoscopic observations of the ovaries confirmed that ocelots and tigrinas did not ovulate spontaneously. In contrast, non‐mating–induced luteal phases of 40.1 ± 6.3 days in duration (range, 30–60 days) were observed frequently in both margays. There was no evidence of gonadal seasonality in margays in either follicular or luteal activity. In ocelots, cyclic changes in estrogen excretion were observed during each month of the year; however, only one female cycled continuously. In the other two ocelots, periods of acyclicity of several months’ duration were observed. It was not possible to conclude whether tigrinas were aseasonal because estrous cyclicity was observed in only one of two individuals. In the female that cycled, a 3‐month period of acyclicity was observed in the late fall/early winter. These data demonstrate similarities among three felid species of the genus Leopardus, including evidence they are polyestrous but experience unexplained periods of ovarian inactivity. Only the margays differed by exhibiting occasional spontaneous, non‐mating–induced ovulations. Historically, these species have not bred well in captivity. However, it is hoped that understanding the biological similarities and differences among them could lead to improved management strategies that may one day result in increased reproductive success. Zoo Biol 20:103–116, 2001. © 2001 Wiley‐Liss, Inc.     

Reproductive parameters of clouded leopards (Neofelis nebulosa)

Reproductive data compiled from the International Clouded Leopard Studbook revealed that 75% of all litters were born to females between one and five years of age. Sixty-three percent of the males had sired litters by four years of age with reproduction declining after six years of age. Sixteen zoological institutions surveyed worldwide contributed estrous cycle data from 28 clouded leopards. Sexual maturity (age at first estrus) for these females ranged from 17 to 28 months of age with a mean estrous cycle length of 29.9 ± 13.8 days. The mean length of estrus was six days. Gestation length ranged from 85 to 121 days (X? = 93.4 ± 6.3). There was a significantly higher incidence of estrus in fall and winter compared with spring and summer over latitudes ranging from 36°–45° and 51°–55° (P < .005). Mating occurred in all months except June and October, and cubs were produced in all months except December. The highest frequency of mating occurred during the month of December corresponding with a birth peak in March.     

圈养马麝(Moschus sifanicus)发情交配节律的比较研究

在1997～2000年间,甘肃兴隆山麝场的圈养马麝发情交配的时间节律保持相对年间恒定,1996年麝场进行了大规模的圈群间动物调整,导致该年的马麝圈群进入发情较迟,发情持续时间也较其他年份长。总体上,圈养马麝的发情持续时间达3个月,而66％的的发情交配发生于1个月内（从11月21日～12月21日）,发情季节（75％的发情完成累计时间）长36天。雌性圈养马麝发情的时间格局受圈养环境的季节性因子影响。饲养人员的饲养风格及各个饲养区内雌性马麝的社会行为的调节效应,各饲养区动物的发情时间格局有显著差异。年龄可影响马麝的发情交配,5．5岁龄以上的马麝发情定时更早。上一年度的繁殖成功与否和当年动物发情迟早无显著相关。野捕圈养麝群和其F1代圈群间的发情时间格局无显著差异。有较多发情周期的个体并不比发情周期仅1～2次的个体更早进入发情。     

Aspects of reproduction in the eastern rufous mouse lemur (Microcebus rufus) and their implications for captive management

The eastern rufous mouse lemur is one of the smallest primate species. It inhabits the eastern rain forest of Madagascar. Its reproductive biology has not been examined because of its rarity in laboratories. We present the first data on reproduction and variation in reproductive success from a breeding colony of wild‐caught Microcebus rufus. The eastern rufous mouse lemur shows a seasonal change in testicular size and in the occurrence of estrus. Females had 2.5 cycles (range, one to four) per season. The estrous cycle length was 59 days (range, 51–66), the duration of vaginal opening during estrus was 7.5 days (range, 5–8), receptivity occurred on the third day of estrus, gestation length was 56.5 days (range, 56–57), litter size was two neonates (range, one to three). The frequency and duration of mating behavior varied widely among the pairs. Copulation seemed to occur on a single day per estrus within the first to fourth hour after light change to red light. In four cases (three pairs), copulation lasted between 15 and 240 seconds. Breeding success can be increased by choosing mates carefully. Microcebus rufus seems to be a seasonal breeder like its sibling species Microcebus murinus. In wild‐caught animals, males seemed to adapt quickly (first season) to the conditions of captivity, whereas in the females, individual variation (first to third season) in reproductive activity was observed. Air humidity of >60% seems to facilitate the breeding success in wild‐caught pairs. First pregnancy and successful rearing of offspring occurred in the second and fourth year of captivity in two of three females. Wild‐caught eastern rufous mouse lemurs seemed to demonstrate variation in adapting to the conditions of captivity with regard to sex and individuality. Zoo Biol 20:157–167, 2001. © 2001 Wiley‐Liss, Inc.     

Short estrous cycles and associated serum progesterone levels in beef cows

Short estrous cycles in beef cows were investigated in two experiments. In trial 1, breeding dates from 2,854 fall-calving Angus cows were used to determine the incidence of short estrous cycles. Of 198 cycles of less than 17 days, 170 were between the first and second detected estrus. Estrous cycles of 7 to 10 days occurred more frequently (P<.005) than other short estrous cycles. Eight-day estrous cycles were most frequent. In the second experiment, calves were weaned from 25 of 33 anestrous spring-calving, crossbred Simmental cows. Compared to herdmates still nursing calves, an increased percentage of cows which had calves weaned were observed in estrus within 10 and 25 days after the date of weaning (P<.005) and a higher percentage had 7- to 10-day estrous cycles. Cows that were observed in estrus within 10 days after weaning were inseminated with Angus semen at their first estrus and with Simmental semen at their second estrus. No cows conceived on the first estrus of 7- to 10-day estrous cycles; 61.5% conceived on the second estrus. Serum progesterone was higher (P<.01) before the second estrus than the first.     

Conditions for establishment of reflex ovulation in light estrous rats.

Continual anovulatory state associating with persistent vaginal cornification (light estrus) was induced by placing 4-day cycling rats under continuous lighting (LL). Uterine cervical stimulation was applied at arbitrary solar hours to light estrous rats showing continual vaginal estrus for more than 2 weeks. The ovulation was induced between 14 and 16 hr after the stimulation dissociating entirely with solar hours. Injection of anti-LHRH serum 5 min after the stimulation but not later than 20 min blocked this ovulation. Ovulation thus induced was always followed by pseudopregnancy with continual leucocytic vaginal smear lasting 10.70 days. The change in concentrations of peripheral serum progesterone during this period was almost similar to that of normal pseudopregnancy except extremely low levels observed at the start and end. Effectiveness of the cervical stimulation for induction of ovulation in light estrous rats was related to not only the duration of light estrus but also the time after transfer to LL, suggesting that the neural mechanism of ovulation in light estrous rats shifted from that of the spontaneous to reflex ovulators due to the extinction of environmental photic cue.     

Gestation length in Tarsius bancanus

A gestation length of 178 days was determined for Tarsius bancanus based on a vaginal smear containing whole sperm. This value replaces the only previously reported information on gestation length in tarsiers, a rough estimate of approximately 6 months for T. syrichta.     

Changes in vulvar and vestibular tissue of the bovine during the estrous cycle as determined by the use of near-infrared interactance

Near-infrared interactance spectra of the vulva and vestibule of cows were analyzed throughout the estrous cycle to determine if they could be used to detect tissue changes that are associated with estrus. The spectra were collected daily from 16 cyclic Holstein cows beginning at 40 days post partum and continuing for 3 estrous cycles, or until pregnancy was verified. Spectra collected on the day when estrus was exhibited were compared with spectra collected on the nonestrous days. There were spectral differences at 1695 to 1705, at 1790 to 1800 and at 1880 to 1900 nm (P<0.05), regions that are associated with changes in carbohydrate, protein, and water content of the tissues, respectively. Discriminant analysis of interactance measurements at the significant wavelengths was used to develop an equation to predict the day of estrus. The error rate associated with the equation was 26%. Results indicate that near-infrared analysis can detect changes in vestibular and vulvar tissue during the estrous cycle. However, accurate estrus detection using near-infrared interactance techniques will require additional study to reduce variation in the results.