ANALYSIS OF CORPORA LUTEA TO ESTIMATE REPRODUCTIVE CYCLES OF WILD HAWAIIAN MONK SEALS (MONACHUS SCHAUINSLANDI)

Ovaries from 14 female Hawaiian monk seals, O-24 yr of age, collected from the northwestern Hawaiian Islands were analyzed by gross and histological examination for the presence of corpora hemorrhagica (CH), lutea (CL), albicantia (CA), and dominant follicles. Seven seals, 5-24 yr of age, were mature females, and another seven seals, O-5 yr of age, were immature based on the presence or absence of CL and CA in the ovaries. Two 5-yr-old seals did not have CL and CA, but one J-yr-old and both 6-yr-old seals had CL or CA. In addition, the weight of the more active ovary increased at 5 yr of age, indicating that puberty in these female Hawaiian monk seals occurred about 5 yr of age. The total number of CL and CA was significantly correlated to the ovarian weight, but not age of the seals, indicating that visible CA of Hawaiian monk seals probably degenerate within a year. If an ovulation resulted in pregnancy, we assumed that the resulting CL from that pregnancy persisted throughout gestation and regressed approximately 2 yr after ovulation. However, the CL of pregnancy were not easily differentiated from cyclic CL that did not result in pregnancy. Four of seven mature seals were clearly polyestrous from the analyses of their ovaries and reproductive histories. The remaining three seals were pregnant in previous consecutive years, and we could not positively determine whether they were also polyestrous. The ovaries from Hawaiian monk seals had unusually large, rounded granular cells containing the aging pigment, lipofuscin. These cells were located between loose fibrous tissues in all regressing CL and CA but were not present in any CH.     

REPRODUCTION IN THE FEMALE SUBANTARCTIC FUR SEAL, ARCTOCEPHALUS TROPICALIS

The reproductive tracts of 89 female subantarctic fur seals, taken at Gough Island between November 1977 and October 1978, were examined. Females started ovulating at age 4 yr and all 6-yr-old females were sexually mature. They are mono-ovulatory, alternating between ovaries, and only single embryos were found. Females older than 13 yr ( n = 11) showed poor follicular development and some failed to ovulate. The gestation period (first recorded ovulation to first recorded birth) was 360 d, while delayed implantation (first recorded ovulation to first recorded implantation) lasted for 139 days. Follicle numbers in the functional ovary declined sharply after ovulation while the corpus luteum increased in size until at least 1 mo prior to parturition. The number of follicles in the contralateral ovary increased after midwinter (June/July), and the mean size of the largest follicles peaked prior to ovulation in December. The mean size of the largest follicles increased in both ovaries near implantation time, after reaching a low subsequent to, ovulation. The regressing corpus albicans, conspicuous for approximately 3 mo after parturition, could not be detected macroscopically within one year postpartum. Subantarctic fur seals at Gough Island have a distinct postreproductive class of older females. The pregnancy rate for all females ≥4 yr of age was 79%, and it was 84.5% for the sexually mature group of ≥6 yr of age, while the mean age at puberty was 4.80 yr.     

AGE, GROWTH, AND REPRODUCTION IN NEW ZEALAND FUR SEALS

Growth and reproductive biology of New Zealand fur seals ( Arctocephalus forsteri ) were studied by examining 127 seals (57 females, 64 males) killed incidentally in fishing gear in New Zealand waters in 1996. Tooth sections were used to age the animals, and male and female reproductive organs were examined macroscopically and histologically. The maximum age observed was 22 yr for females and 12 yr for males. Males were significantly larger than females, but growth was similar up to 5 yr. Males reached sexual maturity between 5 and 9 yr of age, whereas females did so between 4 and 6 yr. The mean pregnancy rate in females was 0.69 (95% CI = 0.54–0.81).     

Ovulation, insemination and mating in the tsetse fly Glossina pallidipes

ABSTRACT. Analyses of the ovulation, insemination and mating of female Glossina pallidipes Austen, were carried out in the field and laboratory. In unmated females, ovulation was delayed until at least the fifteenth day of adult life. The predictable pattern of growth and development of eggs was used to age nulliparous females to the nearest day in the field. Inseminated females first appeared at 5–6 days old and most females became inseminated at 8–10 days of age. There were no significant differences in the age at insemination in Zimbabwe or Kenya. Ovulation had occurred in the field by 10–11 days old. Mating therefore occurs at or just before ovulation. Females were able to mate at up to 12 days old and still produce a viable larva from their first egg. In laboratory flies originating from Uganda, factors which reduced and minimized the effects of disturbance, maximized insemination rate, so that under the best conditions the age at mating was identical to that found in the field. Nevertheless, the insemination rate of Fl generation Zimbabwe flies reared from wild-caught females was negligible. The differences in the laboratory mating behaviour of the Zimbabwe flies and the flies from the long-established colony of Uganda origin, are considered to be due to wild G. pallidipes being easily disturbed under laboratory conditions, whereas colony breeding rapidly selects for passivity. The concept of gross differences in G. pallidipes mating behaviour between geographic areas in thus rejected.     

Effect of transfer of one or two in vitro-produced embryos and post-transfer administration of gonadotropin releasing hormone on pregnancy rates of heat-stressed dairy cattle

Pregnancy rates following transfer of an in vitro-produced (IVP) embryo are often lower than those obtained following transfer of an embryo produced by superovulation. The purpose of the current pair of experiments was to examine two strategies for increasing pregnancy rates in heat stressed, dairy recipients receiving an IVP embryo. One method was to transfer two embryos into the uterine horn ipsilateral to the CL, whereas the other method involved injection of GnRH at Day 11 after the anticipated day of ovulation. In Experiment 1, 32 virgin crossbred heifers and 26 lactating crossbred cows were prepared for timed embryo transfer by being subjected to a timed ovulation protocol. Those having a palpable CL were randomly selected to receive one (n = 31 recipients) or two (n = 27 recipients) embryos on Day 7 after anticipated ovulation. At Day 64 of gestation, the pregnancy rate tended to be higher (P = 0.07) for cows than for heifers. Heifers that received one embryo tended to have a higher pregnancy rate than those that received two embryos (41% versus 20%, respectively) while there was no difference in pregnancy rate for cows that received one or two embryos (57% versus 50%, respectively). Pregnancy loss between Day 64 and 127 only occurred for cows that received two embryos (pregnancy rate at Day 127=17%). Between Day 127 and term, one animal (a cow with a single embryo) lost its pregnancy. There was no difference in pregnancy rates at Day 127 or calving rates between cows and heifers, but females that received two embryos had lower Day-127 pregnancy rates and calving rates than females that received one embryo (P < 0.03). Of the females receiving two embryos that calved, 2 of 5 gave birth to twins. For Experiment 2, 87 multiparous, late lactation, nonpregnant Holstein cows were synchronized for timed embryo transfer as in Experiment 1. Cows received a single embryo in the uterine horn ipsilateral to the ovary containing the CL and received either 100 microg GnRH or vehicle at Day 11 after anticipated ovulation (i.e. 4 days after embryo transfer). There was no difference in pregnancy rate for cows that received the GnRH or vehicle treatment (18% versus 17%, respectively). In conclusion, neither unilateral transfer of two embryos nor administration of GnRH at Day 11 after anticipated ovulation improved pregnancy rates of dairy cattle exposed to heat stress.     

Dramatic shifts in Hawaiian monk seal distribution predicted from divergent regional trends

Total estimated abundance of Hawaiian monk seals was just 1,161 individuals in 2008 and this number is decreasing. Most monk seals reside in the remote Northwestern Hawaiian Islands (NWHI) where the decline is approximately 4%/yr, whereas relatively fewer seals currently occupy the main Hawaiian Islands (MHI). It is widely accepted that the MHI population is increasing, although there are no formal estimates of total abundance, population growth rate or vital rates. This lack of information has hampered efforts to anticipate future scenarios and plan conservation measures. We present the first estimates of MHI monk seal survival and age‐specific reproductive rates. Using these rates, a conservative estimate of current MHI abundance and a previously published stochastic simulation model, we estimate the MHI population growth rate and projected abundance trend. Analogous estimates for the NWHI are derived from a much richer data set. Estimated survival from weaning to age 1 yr is 77% in the MHI, much higher than recent NWHI estimates ranging from 42% to 57%. Moreover, MHI females begin reproducing at a younger age and attain higher birth rates than observed in the NWHI. The estimated MHI intrinsic rate of population growth is 1.07 compared to a 0.89–0.96 range in the NWHI. Assuming an initial abundance of 152 animals in the MHI, projections indicate that if current demographic trends continue, abundance in the NWHI and MHI will equalize in approximately 15 yr. These results underscore the imperative to mitigate the NWHI decline while devoting conservation efforts to foster population growth in the MHI, where documented threats including fishery interactions, direct killing, and disease could rapidly undo the current fragile positive trend.     

Quantification and classification of pregnancy wastage in 5-day cyclic young through middle-aged rats

Fecundity was quantified in 4 to 11-month old rats with regular 5-day cycles. On the day following mating, less than 5% luteinized unruptured follicles occurred in either 4-month old or 11-month old rats; ovulation rate and also fertilization rate were similar in these young and middle-aged rats. At day 19 of pregnancy embryonic and fetal mortalities were quantified. Pregnancy wastage increased gradually with age; it was already significant in 7-month old rats. In rats of 9 months old it was about 30% and in 11-month old rats it was greater than 65%. Pregnancy wastage was mainly due to preimplantation and early-postimplantation mortality. Pregnancy wastage did not decrease when the pre-ovulatory surge of luteinizing hormone (LH) was reinforced and timed, by injection of the LH-releasing hormone analogue Ovalyse at noon on the day of prooestrus. The results corroborate the idea that pregnancy wastage in middle-aged rats with regular cycles is caused by an age-related reduction of the viability of ovulating eggs.     

Sighting patterns reveal unobserved pupping events to revise reproductive rate estimates for Hawaiian monk seals in the main Hawaiian Islands

We used sighting reports, including decades of citizen-reported Hawaiian monk seal (Neomonachus schauinslandi) sightings, to describe female breeding biology and reproductive success in the main Hawaiian Islands. We first used this data set to describe the timing of events in the female reproductive cycle. We then conducted an expert review of patterns in sighting histories to detect unobserved pupping events. Finally, we estimated the age-specific reproductive curve for female monk seals in the main Hawaiian Islands. Charting reproductive cycles showed indications of the robust condition of female monk seals in the main Hawaiian Islands; they nursed pups 12% longer than their counterparts in the Northwestern Hawaiian Islands and regained condition to molt more quickly after weaning a pup. By examining sighting histories, we were able to infer 25 unobserved pupping events that had previously gone uncounted. We accounted for additional uncertainty with a randomization procedure. After accounting for unobserved pupping events, the age-specific reproductive rate of main Hawaiian Islands monk seals exceeded 0.70 for prime aged females (8–18 years). This is the highest reproductive rate reported for any of the Hawaiian monk seal breeding sites, illustrating the important role of the main Hawaiian Islands population in Hawaiian monk seal recovery.     

ENTANGLEMENT IN MAN-MADE DEBRIS OF ANTARCTIC FUR SEALS AT BIRD ISLAND, SOUTH GEORGIA

Neck collars of man-made marine debris were seen on 208 Antarctic fur seals (and removed from 170) during the 142 days of the 1988–1989 pup-rearing season at Bird Island, South Georgia. This represents at least 0.1% of the total Bird Island population and a minimum of 0.4% of animals in the best covered areas; a maximum value might approach 1%. Polypropylene straps (packaging bands) formed 59% of collars, nylon string (16%), fishing net (13%) and six other materials comprised the rest. Males accounted for 71% of entanglements, 88% of which were of young (1–4 yr old) animals; females accounted for 64% of animals older than this. Obvious physical injury was being caused to 30% of animals and only on 19% of animals was the collar loose enough potentially to come off. The magnitude of the problem at South Georgia is similar to that with northern fur seals at the Pribilof Islands, where a significant population decline has occurred concurrently. Antarctic fur seals are still increasing in numbers but stricter controls on the jettisoning of debris into the Southern Ocean ate needed if the entanglement problem is not to increase beyond the level of a potential threat.     

Reproduction in Brahman cows calving for the first time at two or three years of age

A comparison of the subsequent reproduction of heifers that calved for the first time at 2 vs. 3 yr of age was conducted on a purebred Brahman herd from 1971 to 1978 in central Florida. Pregnancy rate, birth rate and weaning rate were obtained on 1,612 animals. Sire of the cow had a significant effect on all three reproduction traits, indicating possible genetic differences in these important traits. Age at first calving (either 2 or 3 yr) had no significant effect on overall reproduction rates; however, subsequent pregnancy and weaning rate was 4% higher in females calving first at 2 yr of age. Thirty-eight percent of the females that became pregnant at 15 to 17 mo of age, weighed 650 to 700 lbs. These heifers had been born early in the previous calving season. It is suggested that Brahmans can be selected to calve at 2 yr of age if good nutrition and management are provided.     

Grey seal (Halichoerus grypus) pup production at North Rona: A study of birth and survival statistics collected in 1972

The Grey seal breeding assembly on North Rona was studied throughout autumn 1972. Weekly censuses provided data on birth rate and mortality. It is estimated that 1736 pups were born in 1972. This is about 500 less than the mean production estimate for this assembly during the period 1959–71, possibly a result of disturbance of the breeding site by the expedition. About 600 of the pups died before putting to sea. The mean date of birth and the duration of the pupping season agree closely with earlier work on North Rona, although the mean daily birth rate curve is somewhat irregular, perhaps because there was an unusually dry spell of weather at a critical time in the pupping season. An improved estimate of mortality at this assembly showed a relationship with pup density similar to that observed at the Fame Islands. Techniques for estimating pup production (and consequently total population), though not reliable for determining absolute values, are useful for indicating trends and they suggest a stable population of 8000–9000 animals at North Rona. Such estimates might be improved by the use of better methods of aerial photography.     

Pregnancy rate of Nelore females inseminated with male-sexed semen

Pregnancy rates of Nelore females inseminated with male-sexed semen and conventional semen from the same bulls were evaluated. The females included 433 heifers (2 years old) and 230 non-suckling cows, totaling 663 animals. Average body condition score was 3.5 (1-5 scale). Estrus was induced with prostaglandin F2α. The total pregnancy rate of females inseminated with male-sexed semen of bulls A, B and C was 38.8% (131/338) less (P<0.0001) than the total pregnancy rate observed for females inseminated with conventional semen from the same bulls (57.9% [188/325]). Pregnancy rates of non-suckling cows inseminated with male-sexed semen was 43.3% (49/113), which was similar (P≥0.05) to the values found for heifers inseminated with male-sexed semen from the same bulls (36.4% [82/225]). The pregnancy rate of females inseminated with male-sexed semen was less compared with females inseminated with conventional semen. In addition, there was no significant difference in the pregnancy rate of heifers versus non-suckling cows.     

ESTIMATION OF AGE-SPECIFIC PROBABILITIES OF FIRST RETURN AND ANNUAL SURVIVAL RATES FOR THE MALE GRAY SEAL (HALICHOERUS GRYPUS) ON SABLE ISLAND FROM CAPTURE-RECAPTURE DATA

We used a longitudinal capture-recapture study to estimate the age-specific probabilities of first return to the breeding colony and annual survival rates for male gray seals ( Halichoerus grypus ), based on resightings of seals branded as young on Sable Island. We estimated that the average age of first returns for seals born in 1969–1970 to be 9.1 (SE 0.4) yr; for seals born in 1973–1974 it is estimated to be 9.8 (SE 0.2) yr. The estimated annual survival rate of these males was estimated to be 0.976 (SE 0.003).     

The effect of the gonadotrophin-releasing hormone analog, buserelin, administered in diestrus on pregnancy rates and pregnancy failure in mares

Two trials involving 578 mares were performed to investigate the effect of a single intramuscular treatment of 40 microg buserelin, an analog of gonadotrophin releasing hormone, on pregnancy rate in mares. All mares were bred by natural mating and were allocated into pairs One mare in each pair was injected with buserelin either on Day 10 or 11 (Trial 1) or on Days 8 to 10 (Trial 2) after ovulation. Pregnancy status of mares was determined by transrectal ultrasonographic examination on Day 14 or 15 after the day of ovulation and was repeated between Days 28 and 30 of pregnancy. In Trial 1, buserelin treatment increased the pregnancy rate at Days 14 and 15 (72.5 vs 66.6%, P < 0.01). At the second pregnancy examination, pregnancy losses were lower in the treated group of mares (4.1 vs 7.4%; P < 0.05). In Trial 2, buserelin also improved the pregnancy rate (57.2 vs 53 5%; P < 0.05) at Days 14 and 15 Pregnancy losses between the first and second examinations were lower in the treated group of mares (6.5 vs 12.0%; P < 0.05). Buserelin increased pregnancy rates after breeding at the first estrus in both trials. In addition, buserelin treatment increased the pregnancy maintenance rate at Days 28 to 30.     

Reproductive biology of female striped dolphin (Stenella coeruleoalba) from the western Mediterranean

Data on age and length at sexual maturity, calving interval, lactation period, and ovulation and pregnancy rates were analysed from 84 female striped dolphin collected during the Mediterranean morbillivirus epizootic. Age was determined by counting growth layer groups in tooth dentine, and reproductive status was determined by the macroscopic examination of the ovaries and the uterus. Age at sexual maturity (ASM) was estimated using two different methods; giving average estimates of 12 and 12.3 years. The average length at sexual maturity was 187 cm and the calving interval was four years. The annual pregnancy rate (APR) was calculated using two different criteria. In the first, only females that were pregnant at the time of death, as evidenced by the presence of a foetus, were incorporated in the calculations. This method gave an estimate of 8.9% as the apparent pregnancy rate of the dolphins killed by the epizootic. The second method incorporated in the calculations females that were pregnant at the time of death and females that had young corpus albicans in the ovaries and a distended uterus. This method is considered to reflect the true pregnancy rate of the population and gave an estimate of 25%. Estimates of ovulation rate (0.401) and lactation period (16 months) were considered to be potentially affected by the disease and, therefore, biased. These estimates reflect a peculiar situation of the diseased dolphins but are useful for comparative purposes. Estimates of ASM and APR, parameters which are not likely to be affected by the disease, differed markedly from those of other Stenella populations and could indicate a density-dependent response, possibly reflecting food limitations.     

Reproductive biology and ecology of female polar bears (Ursus maritimus)

Data on age-specific natality rates, litter size, interbirth interval, age of first reproduction, reproductive senescence, age of weaning and cub survival were determined for a free-ranging population of polar bears inhabiting Hudson Bay, Canada, near the southern limit of the species range. Serum progesterone levels were also determined for females at different stages of their reproductive cycle to provide corroborative support for the reproductive parameters described. Animals were live captured using immobilizing drugs and each animal uniquely marked for future identification. First parturition occurred at four or five years of age and the age-specific natality rate increased with age until approximately 20 years, after which it dropped markedly. At least 40% of adult females displayed two-year interbirth intervals and 55% of cubs in their second year were independent of their mother. Mean size of cub litters in spring was 1.9 and 13% of litters had three or more cubs. The natality rate for 5–20-year-old females was estimated as 0.9, higher than that reported for any more northerly polar bear populations where two-year interbirth intervals are rare, fewer than 5% of yearling cubs are weaned and triplet litters occur with less than 1% frequency. Cub mortality was initially high and declined with age. Although cubs in western Hudson Bay were weaned at a younger age and a lighter weight than their counterparts in more northern populations, cub mortality rates were similar. The reason for the marked differences in reproductive parameters in the western Hudson Bay population is not known. We speculate that sea-ice conditions may be sufficiently different to allow weaned bears at a lighter body weight to hunt seals more successfully there than further north.     

The contemporary condition and some demographic characteristics of the Steller sea lion (<Emphasis Type="Italic">Eumetopias jubatus</Emphasis>) reproductive group on Tyuleniy Island,Sea of Okhotsk

In 2010, the largest part of the Steller sea lion breeding community on Tyuleniy Island was located on the harem rookery of northern fur seals, which occupied the eastern beach, as well as on the western side of the island, which was free of fur seals. At the culmination of harem activity on June 29, 26.5% of the animals at the age of 1+ concentrated on the eastern beach and 41.1%, on the western beach in the daytime. However, 52.3% of the pups were born on the eastern beach and only 30.4% were born on the western beach. Pups were also present on the capes: 9.1% of the pups were observed on the northern cape and 8.2% on the southern cape, while the main population on these sites consisted of non-harem bulls, bachelors, and young animals. At the peak of harem activity, the number of females per one harem bull was 13.1 at sites 1 to 3 of the eastern beach and each of them, on average, had 1.05 pups; on sites 7–12 there were, respectively, 9.1 females and 1.42 pups per female, and on the western beach, 21.7 females and 0.64 pups. The resulting abundance of sea lions on Tyuleniy Island in 2010 exceeded 1500, which was almost ten times as many as their number in 1989. A total of about 100 bulls, 60 harem bulls, 1000 females, and 700 pups were recorded there. Half-bulls and young animals amounted to one-third of the entire population. Meanwhile the overall sex ratio at the culmination of harem activity was 11.5 females per one bull and 18.8 per one harem bull. About 75% of the females belonged to the parous group. The mortality rate among newborns reached 5.4%. No mortality was observed in adults. As many as 133 previously branded Steller sea lions were found and 109 of them (81.9%) were immigrants. Among immigrants, 29% were branded individuals of reproductive groups from the Kuril Islands, 54% were from the Iony Islands, 16% were from the Yamsky Islands, and about 1% were from Kamchatka. Four-year-old individuals predominated among the branded immigrants (23.8%). The oldest Steller sea lion (21 years of age) was one that was branded on the Srednego Islands in 1989. The rate of marked animal return from 175 pups that were branded on Tyuleniy Island the year before was 13.8%.     

LIFE HISTORY OF FRASER'S DOLPHIN, LAGENODELPHIS HOSEI, BASED ON A SCHOOL CAPTURED OFF THE PACIFIC COAST OF JAPAN

Life history of Fraser's dolphin, a little known delphinid species, was examined based on 108 specimens from a school captured by the driving fishing method in Japan. The sex ratio was approximately 1:1, and mature dolphins of both sexes formed the bulk of the school. The oldest animals were two males and a female of 17.5 yr. Age and body length at sexual maturity were estimated at 7–10 yr and 220–230 cm in males and 5–8 yr and 210–220 cm in females. Mature males were larger in body length than mature females and showed apparent secondary sexual features: deepening of the tail stock and widening and darkening of the lateral dark stripe. The annual ovulation rate was 0.49. The estimated neonatal length (110 cm) predicts a gestation period of about 12.5 mo and calving peaks in spring and probably also in fall. The calving interval was estimated to be about 2 yr. These life history parameters are similar to those of the striped and pantropical spotted dolphins, except for longevity. The reproductive rate of this species may be lower than that of other pelagic delphinids, if the observed shorter longevity is real.     

Seasonal variation in energy intake and condition of harp seals: Is there a harp seal morph? Problems for bioenergetic modelling

Seasonal changes in mass, fat depth, condition index and energy intake were measured in eight captive harp seals (Phoca groenlandica) over a 15-month period. Two of the five adult females were pregnant but lost their pups before term. There were large shifts in all variables measured. The range of these changes in the individual adult animals were for mass, 15–89%, blubber depth 56–240%, and condition index 13–23% (girth x 100)/length. Daily energy consumption varied from as little as 1.16 MJ to as much as 70.97 MJ. The two young males showed larger seasonal changes than the adults. Consistent with our earlier studies of harbour seals (Phoca vitulina) , there was either a significantly negative or no correlation between energy intake and changes in mass or fat. Mass and blubber thickness were positively related in the male seals, however, this was true of the females only during spring and summer. Water and air temperature varied indirectly with changes in blubber thickness in all but two seals. It is proposed that metabolic rate varies seasonally in seals. The implications of these findings are discussed in the light of their impact on bioenergetic modelling.     

Pregnancy in the domestic cat after vaginal or transcervical insemination with fresh and frozen semen

The objective was to compare pregnancy rates in domestic cats using fresh semen for intravaginal artificial insemination (IVI), either at the time of hCG treatment for induction of ovulation, or 28 h later, and to compare pregnancy rates following IVI or transcervical intrauterine insemination (IUI) of frozen-thawed semen. Eighteen queens were inseminated during 39 estrus cycles. Fresh semen with 13.5+/-5.4 x 10(6) sperm (range, 6.8-22 x 10(6)) collected by electroejaculation from four male cats was used in Experiment 1, and cryopreserved semen (20 x 10(6) sperm, with 70+/-5% post-thaw motility) from one male cat was used in Experiment 2. Serum concentrations of estradiol-17beta and progesterone were determined in most queens on the day of AI and again 30-40 days later. Treatment with 100 IU of hCG 3 days after the onset of estrus induced ovulation in 95% of treated queens. Pregnancy rates to IVI with fresh semen at the time of hCG administration versus 28 h later were not different (P=0.58); overall 33% (5/15) of the queens became pregnant. For frozen-thawed semen, AI was consistently done 28h after hCG administration; IUI and IVI resulted in pregnancy rates of 41.7% (5/12), whereas no queen (0/12) became pregnant by IVI (P=0.0083). In conclusion, an acceptable pregnancy rate was obtained with frozen-thawed semen in the domestic cat by non-surgical transcervical IUI; this method might also be useful in other small felids.