Previous Insemination Research Articles

P–079 A spontaneous LH peak before triggering for intrauterine insemination with donor sperm (IUI-D) is associated to lower live birth rates

Abstract Study question Are live birth rates after IUI with donor sperm (IUI-D) and controlled ovarian stimulation comparable between women with a spontaneous LH peak vs those without? Summary answer Biochemical, clinical, ongoing pregnancy rates and live birth rates were higher among women without an LH peak. What is known already It is common clinical practice to trigger ovulation in IUI cycles once specific criteria are met; if a natural LH surge appears, adjusting the IUI timing may become necessary. Pregnancy rates seem to be slightly better when IUI is scheduled in relation to the presence or absence of an LH peak in non-stimulated cycles. In IUI with stimulated cycles, however, there is no consensus in the medical literature regarding the best moment to program the IUI, due to different inclusion criteria, different IUI timing and definition of LH peak among studies. Study design, size, duration Retrospective cohort study of 9,657 IUI-D cycles performed between 2012 and 2019 in one fertility center. IUI-D without LH peak (n = 6,679) versus IUI-D with LH peak (n = 2,978) were compared. Differences in pregnancy outcomes between study groups were evaluated using a Pearson’s Chi2 test. A p < 0.05 was considered statistically significant. Participants/materials, setting, methods The definition used to define an LH peak is > 10UI/L in the last follicular control. In cases without an LH peak, when at least one dominant follicle reached 17mm, ovulation was triggered with human chorionic gonadotropin in the following 24h, and IUI-D was performed 38h after triggering. In cases with an LH peak, ovulation was triggered the 6h following the detection, and IUI-D was also performed 38h later. Main results and the role of chance The women BMI and age were comparable between groups, with a mean±SD of 35.2±4.8 years old, and 24.3±4.7 for BMI. Other characteristics such as number of previous inseminations, type of stimulation drug, initial dose, total dose, stimulation length and number of follicles > 16mm in the last follicular control were also comparable. As expected, the LH level at the last follicular control was different between groups, with a mean of 5.1UI/L in the no-LH peak and 21.4IU/L in the LH peak group. The group without an LH peak had higher biochemical, clinical, ongoing and live birth rates compared to the group with LH peak: 27.7% vs. 20.7%; 19.5% vs. 15.5%; 17.7% vs. 13.7%; 16.3% vs. 12.6%, respectively (p-value<0.001). Limitations, reasons for caution The main limitation of the study is its retrospective nature. Also, a definition of LH peak based in absolute values was used; a definition based in relative values may lead to different results. Wider implications of the findings: A definition of LH peak based on absolute numbers is imprecise, and the cut-off of 10UI/L does not allow a good scheduling for IUI. A LH peak based on relative values could improve the detection of patients starting ovulation and the accuracy in programming IUI. Trial registration number Not applicable

Resynchronizing the first eligible estrus in dairy cattle after a prior insemination and fertility of the prior insemination after gonadotropin-releasing hormone and progesterone treatments

The hypothesis of this study tested whether application of designed treatments to synchronize estrus in nonpregnant previously inseminated lactating dairy cows increased the proportion of nonpregnant cows in estrus before early pregnancy diagnosis on Day 32 after the previous insemination (Day 0) and increase fertility of the pretreatment insemination. A progesterone insert (CIDR) and GnRH were applied to cows after insemination to resynchronize the returning estrus of cows that failed to conceive on Day 0. The combination of GnRH (Day 14) and a CIDR insert (d 17 through 24) in experiment 1 (n = 347 cows) did not increase (P = 0.13) the proportion of nonpregnant cows returning to estrus before pregnancy diagnosis, but increased (P < 0.01) the synchrony of their return by 24.4% points, and delayed (P < 0.01) that return by 2.3 ± 0.3 d compared with controls. Ovulation risk after GnRH treatment on Day 14 was only 10%. For cows that failed to return to estrus before Day 32, progesterone concentration on Days 14 and 17 were less than that in cows that returned to estrus by Day 32 and in pregnant cows. Cows that returned to estrus had larger follicles and fewer numbers of CL on Day 21 than pregnant cows and cows that failed to return to estrus, but concentrations of pregnancy-associated glycoproteins on Day 28 indicated that cows failing to return to estrus were likely pregnant but suffered embryo death. In experiment 2 (n = 881), use of GnRH alone (Day 7), a CIDR insert alone (Days 14 through 21), or in combination, failed to increase the proportion of nonpregnant cows in estrus before pregnancy diagnosis on Day 32 compared with controls. Cows receiving the CIDR insert had increased (P < 0.01) synchrony of estrus by 24–34% points compared with cows that did not receive a CIDR insert. More cows receiving GnRH had 2 or more CL on Days 14 and 21 compared with controls. Ovulation risk after GnRH on Day 7 was greater than 66%. In both experiments combined, treatments with GnRH or GnRH + CIDR insert increased (P = 0.015) pretreatment pregnancy per AI by 7.1% points, but did not affect pregnancy loss. Although administering GnRH with or without a CIDR insert synchronized returns to estrus, treatments failed to increase the proportion of nonpregnant cows reinseminated before pregnancy diagnosis, but increased pretreatment pregnancy risk.

Investigation of Effective Factors on Calving Interval of Cows in Faryab Province

This research was conducted to investigate the effects of factors (Identification of female cows, timely insemination of identified begging cows, diseases related to the reproductive system and nutrition) on the calving interval of dairy cows in Faryab province. Whereas, the long interval between two deliveries due to the identification of female cows, the increase in the number of inseminations (due to the failure of previous insemination), poor nutritional management and genital infections cause a long interval between calving to retrieval of cows. In that case, it will significantly reduce milk production and livestock income, because calving interval is one of the most important indicators of reproduction and economic characteristics of dairy cows, which is the interval between two calving intervals. Under the best of circumstances, one cow gives birth to only one calf per year. Calves born are important from both the point of view of meat production and replacement of old and low-producing cows. Identifying the effective factors and their effects on the calving interval between dairy cows and preventing the economic losses of dairy farmers due to increasing the calving interval between calves are the general purpose of this research. In this research, Andkhoy, Qurghan and other Faryab districts were randomly selected from three villages in each district and 10 owners from each village, which included three districts, 9 villages and nine livestock, respectively. The results of the present research showed that the interval between calving of dairy cows in the research area was due to the untimely identification of female cows by herders, increasing the number of inseminations due to the failure of previous inseminations of diseases related to the reproductive system and inadequate nutrition. The average time after delivery for the uterus to return to its previous state was 465 days.

Effect of heat stress on age at first calving of Japanese Black cows in Okinawa.

Calving records from birth certificates of cows were analyzed to investigate the effect of heat stress on age at first calving (AFC) of Japanese Black cows. The data set covered 20 years (1990-2009) of calving records. Total number of records was 9279. Daily weather information from weather stations in the vicinity of the farms was used. Temperature-humidity index (THI) fitted to a linear model covered 30 days pre-insemination to 61 days post-insemination. Statistical analysis was conducted with procedures of SAS/STAT. Preliminary analysis showed that THI of the lowest temperature and humidity was most conducive to AFC. Covariance analysis, including main effect of sire, farm and year of insemination and covariates of THI on days showed that regression coefficients of THI on day -7, day -2 and day +31 were statistically significant. The estimated piecewise regression line showed different responses of AFC to THI on days: roof-shasped downward trend on day -7, hockey-stick shaped upward trend on day -2 and day +31. The difference among the estimated regression lines may be caused by direct and indirect factors on reproduction: indirect effect of reduced feed intake, failure of conception at previous insemination, direct effect of heat stress on oocyte and embryo development.

Ovarian responses and embryo survival in recipient lactating Holstein cows treated with equine chorionic gonadotropin

The objectives of Experiment 1 were to determine a dose of eCG that would increase total luteal volume and plasma progesterone (P4) concentration on estrous cycle Day 7 in cows. The objectives of Experiment 2 were to determine the effects of treating embryo recipient lactating Holstein cows with eCG on pregnancy per embryo transfer (P/ET). In Experiment 1, lactating dairy cows at 63 ± 3 d postpartum (DIM) received no treatment (control, n = 10), or 600 (eCG6, n = 19), or 800 (eCG8, n = 19) IU of eCG 2 d after the start of the ovulation-synchronization protocol, Day -8 (Day -10 GnRH, Day -3 PGF 2α, Day 0 GnRH). Blood was sampled on Days -10, -8, -3, 0, 7, and 14 for P4 concentration. Ovaries were examined by ultrasound on Days -10, -3, 0, and 7. In Experiment 2, lactating dairy cows were paired according to parity and previous insemination (0 or > 1 insemination) and assigned to receive 800 IU of eCG (eCG8, n = 152) 2 d after the start of the ovulation-synchronization protocol (Day -10 GnRH, Day -3 PGF 2α, Day 0 GnRH) or to receive no treatment (control, n = 162). Blood was sampled on Days -10, -3, 0, 7, and 14 for determination of P4 concentration. Ovaries were examined by ultrasound on Days -10, -3, and 7, and cows with a CL > 20 mm in diameter on Day 7 received an embryo. In Experiment 1, P4 concentration on Day 7 was higher ( P < 0.05) for eCG8 cows (2.3 ± 0.3 ng/mL) compared with control (1.2 ± 0.3 ng/mL) and eCG6 (1.1 ± 0.3 ng/mL) cows. In Experiment 2, eCG8 primiparous cows had more ( P < 0.01) follicles > 10 mm on Day -3 compared with control primiparous cows (2.5 ± 0.9 vs 1.7 ± 0.5 mm), but multiparous control and eCG8 cows did not differ. A larger ( P = 0.03) percentage of control cows received an embryo (87.5 vs 79.1%) compared with eCG8 cows. Among cows that received an embryo, total luteal volume on Day 7 was affected ( P = 0.05) by treatment (eCG8 = 8.3 ± 0.4 cm 3, control = 6.2 ± 0.4 cm 3), but P4 concentration on Day 7 did not differ significantly between treatments. The percentage of cows pregnant 53 d after ET (overall, 24.2%) was not significantly different between control and eCG8 cows. In the current study, no differences in P/ET were observed between control and eCG8 cows and treatment with eCG increased the percentage of cows with asynchronous estrous cycle.

İneklerde Bulanık Mantık Modeli ile Hareketlilik Ölçüsünden Yararlanılarak Kızgınlığın Tespiti

Summary The aim of this study was the accurately oestrus detection of cows by fuzzy logic model, where the traits activity, movement behavior of cows and period since last oestrus was used simultaneously. The animal material of the study formed the 117 Holstein cows in different ages grown up in private farm. The trait activity was measured by pedometer, which were attached at the left foreleg of each cow. The trait period since last oestrus include information about previous inseminations and oestrus cases. It was also used the certain input named cow’s type which determined the cow’s movement behavior. As the result of the study, the rate of the detection of cows in oestrus by using fuzzy logic system was considerable quite high as 98.0% was determined.

150 EXAMINATION OF ESTRUS SYNCHRONIZATION USING A PRID® + PROSTAGLANDIN F2α AND PREGNANCY RATE AFTER ARTIFICIAL INSEMINATION FOLLOWING TRANSFER OF IN VITRO-PRODUCED EMBRYOS IN REPEAT-BREEDING COWS

Repeat-breeding Holstein cows (RBCs), i.e. cows that have undergone three or more AIs, have reduced pregnancy rates. The present study aimed to determine whether application of a combination of a PRID� (ASKA Pharmaceutical Co., Inc., Tokyo, Japan) + prostaglandin F2α (PGF2α) for estrus synchronization and AI + embryo transfer (ET) would improve pregnancy rates in RBCs. All RBCs selected showed a normal interval between the previous insemination and estrus, and were free of clinical disorders. The RBCs (n = 107) received a PRID for 9 days with a capsule containing 10 mg of estradiol benzoate, 0.5 mg IM of cloprostenol (PGF2α, Resipron�-C; ASKA, Japan) at 2 days before PRID removal. The cows were inseminated with frozen–thawed semen from a bull at 0 to 12 h after onset of estrus. Seven days after AI, single in vitro-produced embryos were transferred to the same RBCs. Pregnancy was diagnosed by palpation per rectum at e60 days post-insemination. Exp. 1 estimated the response to estrus synchronization treatment (n = 107). The factors examined were lactation number (mean � SD: 2.3 � 1.5, range: 1–6), insemination number (5.2 � 2.2, range: 3–13), and the interval from calving to next AI (275.9 � 97.6 days, range: 93–650 days). Exp. 2 compared the pregnancy rate in control RBCs (n = 161) and PRID-treated RBCs (n = 100). The factors examined included lactation number (2.5 � 1.6, range: 1–12), insemination number (6.0 � 2.5, range: 3–19), the interval from calving to next AI (288.0 � 102.1 days, range: 102–797 days), and whether the ET was into the uterine horn ipsilateral or contralateral to the CL in a total of 261 RBCs. Data were analyzed using logistic regression. The results for Exp. 1: 103 cows (96.3%) were confirmed to be in estrus (2.0 � 0.3 days after PRID removal). Although the frequency of estrus was affected by the lactation number (P = 0.014) and the interval from calving to the first AI (P = 0.005), the AI number did not have an affect (P = 0.624). Exp. 2: PRID synchronization had no effect on pregnancy rate (control: 37.3%, 60/161; and PRID-treated: 40.0%, 40/100). For the RBCs, the pregnancy rate was not affected by lactation number (P = 0.093), AI number (P = 0.694), or the interval from calving to next AI (P = 0.762). No significant difference (P = 0.428) in pregnancy rate was observed in cows when the embryos were transferred into the uterine horn contralateral to the CL (43.5%, 20/46), compared to those embryos transferred into the uterus horn ipsilateral to the CL (37.2%, 80/215). In conclusion, our findings suggest that the pregnancy rate may be improved by considering lactation number and the interval from calving to the next AI of RBCs in estrus synchronization using a combination of PRID + PGF2α and AI + ET.

The effect of a progesterone releasing intravaginal device (PRID) on pregnancy risk to fixed-time insemination following diagnosis of non-pregnancy in dairy cows

The objective was to compare the probability of pregnancy after fixed-time insemination in cows diagnosed as non-pregnant and re-inseminated following the Ovsynch protocol, with or without exogenous progesterone. Cows ( n = 415) used in this study originated from 25 farms. Upon diagnosis of non-pregnancy between 30 and 60 days after AI, cows were randomly assigned to receive either a progesterone releasing intravaginal device (PRID; n = 208) or a placebo intravaginal device (PID; n = 207). All cows received GnRH at enrollment (Day 0), PGF 2α concurrent with intravaginal device removal 7 days later, GnRH on Day 9 and fixed-time insemination 16 h later (Day 10). Cows observed in estrus prior to Day 7, had the device removed and were inseminated. Ovaries were examined by transrectal palpation at the time of enrollment and the prominent structures were assessed and recorded. Body condition score, lameness status, interval from previous insemination, and times bred at enrollment were recorded. At intravaginal device removal, the occurrence and intensity of vaginitis was determined according to the amount of debris on the device. Overall, the intravaginal device retention rate was 91%. A total of 5.2% of PID-treated cows and 2.9% of PRID-treated cows were detected in estrus within the 7 days treatment period. Pregnancy status was diagnosed between 30 and 56 days after insemination and all cows were followed for a minimum of 150 days after enrollment. Approximately 28% of cows had evidence of mild vaginitis in response to the intravaginal device, whereas 6% of cows had copious debris associated with the intravaginal device at removal. The probability of pregnancy after fixed-time insemination was 43.8% versus 34.9% in PRID-treated versus PID-treated animals. Exogenous progesterone provided through an intravaginal device to non-pregnant cows that had not displayed estrus improved the probability of pregnancy after fixed-time AI.

Bovine Claw and Limb Disorders Related to Reproductive Performance and Production Diseases

As part of a cross-sectional study of Norwegian Red Cattle, associations of lameness, lesions at the tarsus, claw shapes, and claw lesions with reproductive performance and production diseases were examined. Fifty-five tiestall herds and 57 freestall herds were sampled by computerized systematic selection and 2,665 cows were trimmed and limb and claw disorders recorded by 13 specifically trained claw trimmers during the late winter and spring of 2002. After exclusions, 2,583 cows were included in this study. Most claw lesions were mild (score 1). Prevalence of moderate and severe lesions (score 2 + 3) did not exceed 5% for any of the lesions. Hazard ratios for independent variables were identified using Cox regression analyses incorporating herd as a random effect in a positive stable frailty model. Wounds and swellings at the tarsus were associated with more clinical mastitis [hazard ratio (HR) = 4.0] and teat injuries (HR = 2.5). Moderate and severe heel-horn erosions in first-lactation cows were associated with increased calving interval (HR = 0.60). Moderate and severe hemorrhages of the sole in first-lactation cows were associated with decreased interval from calving to first service (HR = 1.6) and moderate and severe hemorrhages of the sole were associated with more milk fever (HR = 8.6). All hemorrhages of the sole (scores = 1, 2, and 3) were associated with more reproductive hormonal treatments (HR = 2.3). All sole ulcers in first-lactation cows were associated with longer interval from calving to last service (HR = 0.59) and longer calving interval (HR = 0.61), whereas sole ulcers in older cows were associated with longer calving interval (HR = 0.62). All sole ulcers also were associated with more milk fever (HR = 4.8) in all cows. Moderate and severe sole ulcers in older cows were associated with increased interval from calving to first (HR = 0.35) and last (HR = 0.37) service. Moderate and severe white-line fissures in older cows were associated with increased return rate from previous insemination (HR = 2.4). Our study shows that claw disorders are associated with poorer reproductive performance and some production diseases.

Antisperm antibodies of the Ig a class in the cervical mucus and sera of artificially inseminated cows

The aim of this study was to investigate the level of anti-sperm antibodies of the Ig A class in the cervical mucus and sera of artificially inseminated cows. Cervical mucus and sera samples were collected on the day of artificial insemination and the animals were divided into four groups of 20 cows each according to the number of previous inseminations. The titer of antibodies was determined by the indirect immunofluorescence method using sperm cells suspended in Tris egg-yolk extender or the commercial extender "Biociphos +". Our results indicate that titers of antisperm antibodies of the Ig A class elevate with the number of artificial inseminations. Mean titer values were higher in the cervical mucus samples than in sera indicating that the local immune response is more relevant for the immunological reactivity to sperm and extender antigens. In addition, the titer of antisperm antibodies was generally higher when sperm cells suspended in Tris egg-yolk extender were used for the test.

Preprandial inhibition of re-mating in Ixodes ticks (Acari: Ixodidae).

Questing female blacklegged ticks, Ixodes scapularis, Say in Massachusetts rarely bear more than one endospermatophore in their reproductive tracts. We evaluated the cause of this nonrandom distribution by examining the stability of endospermatophore retention in females and the effect of prior insemination of females on the copulatory behavior of male ticks. Endospermatophores were retained without degradation in unfed female ticks for >1 yr at 5 degrees C and for at least 4 mo at 21 degrees C. Males were much more likely to abort preprandial (before feeding) copulations without inseminating females bearing endospermatophores. This remating inhibition activity persisted in unfed females for at least 2 mo after insemination. Perprandial (during feedng) copulations were less restrictive, particularly when females became partially engorged. Males were more likely to remain in copula with previously inseminated females that were engorged, but generally did not transfer spermatophores to them until their fifth day of attachment to a rabbit. Little inhibitory activity was evident during the final, rapid engorgement phase of feeding. Thus, remating inhibition appears to degrade as feeding progresses. In summary, an unknown factor associated with the previous insemination of females inhibits subsequent spermatophore transfer by causing mating pairs to interrupt copulation soon after initiation. Remating inhibition is strongest in unfed ticks and becomes less apparent as females become engorged.

Drosophila sperm and the fight to fertilize

Genes that are directly involved in reproductive success are under intense selective pressure, and life at the sharp end of evolution is no more readily observed than in the case of sperm competition. That such competition occurs in man is controversial, but sperm wars are particularly well documented in Drosophila. Female drosopholids store sperm from successive mates, and the last male to inseminate fathers most of the offspring. The obvious explanation is that the organisation of the female’s sperm stores means simply ‘last in, first out’. Given the prize at stake, something more devious than a gentlemanly, ‘after-you-old-chap’ arrangement was always suspected, but hard to prove. Some researchers, although not all, found that new seminal fluid can disable sperm from previous inseminations. To re-examine this phenomenon, Price et al.1xSperm competition between Drosophila males involves both displacement and incapacitation. Price, C.S.C. et al. Nature. 1999; 400: 449–452Crossref | PubMed | Scopus (122)See all References1 used spermless mutant males (XO males) to inseminate females two or seven days after a previous mating, and found that the spermless seminal fluid reduced fertilization by seven day-old sperm – but not as much as a normal ejaculate – and had no effect on two-day-old sperm. The seminal fluid seems to block or incapacitate the seven-day-old sperm because the latter does not disappear. Next, to look at normal ejaculate, Price et al.1xSperm competition between Drosophila males involves both displacement and incapacitation. Price, C.S.C. et al. Nature. 1999; 400: 449–452Crossref | PubMed | Scopus (122)See all References1 produced a strain of flies that express green fluorescent protein in their sperm tails and watched how these sperm went about jumping the queue. Seemingly, the first male’s sperm are physically displaced, though not through lack of space. How precisely the mechanisms of displacement and incapacitation work is a mystery, as is the role played by the female manipulating or selecting sperm. No doubt, though, there is a vigorous genetic arms race going on underneath.

Aging, hyaluronidase removal of the cumulus, and microinjection do not affect the sperm binding potential of human oocytes.

We studied the influence of aging, hyaluronidase removal of the cumulus, and microinjection on the sperm binding potential of human oocytes under intact zona assay conditions to determine the safe use of unstored aged unfertilized ICSI oocytes on zona binding tests. Results were also compared with those for aged IVF oocytes under the same conditions. To avoid the large variation in sperm binding scores, we compared the ratios of the number of sperm bound to nontreated versus to treated oocytes. Treated oocytes were those whose zonae were exposed to hyaluronidase, an agent that decreases sperm binding. Experimental groups were fresh oocytes, experimentally aged fresh oocytes, fresh oocytes whose cumulus was removed either mechanically or with hyaluronidase, aged ICSI oocytes, and aged IVF oocytes. Statistical analysis within and between groups showed that aging, previous insemination, cumulus removal by hyaluronidase, and microinjection did not affect the sperm binding potential of human oocytes. As the zona binding ability of fresh and unfertilized aged ICSI oocytes is similar, they can be used safely in zona assays.

Failure of gonadotropin-releasing hormone or human chorionic gonadotropin to enhance the fertility of repeat-breeder cows when administered at the time of insemination

Repeat-breeder dairy cows failing to conceive to two previous inseminations were injected with saline (2 cc i.m.), gonadotropin-releasing hormone (GnRH, 2 cc i.m.) or human chorionic gonadotropin (hCG, 5000 IU i.v.) at the time of the third and succeeding inseminations. This field study involved 240 cows at three dairies. Mean conception rate was high (49.6%) for repeat-breeders, and did not differ among farms (P>0.10) or treatments (P>0.10), varying from 44.0 to 51.9% for farms and from 44.4 to 54.2% for treatments. The percentage of repeat-breeder cows bred during diestrus was very low on each of the three farms (mean = 7.9%). For this and other reasons discussed in the study, hormonal therapy was not successful in improving the conception rate of repeat-breeder cows under field conditions.

The demanian system, traumatic insemination and reproductive strategy in Oncholaimus oxyuris Ditlevsen (Nematoda, Oncholaimina)

Observations on living specimens confirm the hypothesis formulated by Chabaud et al. about traumatic insemination in Oncholaimus oxyuris. A detailed description is given of the copulation, the formation of copulation pores, interstitial channels and the injection of glandular material and sperm. The terminal structures of the demanian system of O. oxyuris are not pre‐existing structures, but are built by the combined action of males, ejaculatory and female substances. The injected sperm is temporarily stored around the uvette in the main duct; from there they reach the uterus through the ductus uterinus. With each copulation, a new copulation pore and interstitial channel are formed. After withdrawal of the spicules a ‘wound plug’ seals the pore. When copulations follow at short intervals, sperm of the previous insemination are evacuated to the intestine through the osmosium. The hypothesis is formulated that subsequent copulations result in the fertilization of subsequent egg masses by different males.

Rearing and Postembryonic Development of the Myodocopid Ostracode Skogsbergia Lerneri From Coral Reefs of Belize and the Bahamas

ABSTRACT Skogsbergialerneri (Kornicker, 1958) is the second species of the ostracode order Myodocopida to be fully reared. S. lerneri, a meroplanktonic scavenger, was abundant in baited jar traps set on the barrier reef off Belize, Central America, and at San Salvador Island, Bahamas. Live material was maintained in a coral reef aquarium and in small dishes. S. lerneri had 5 subadult instars and required 65-93 days to reach maturity, measured from the time eggs first became visible in the ovary. Brooding time in the marsupium was 14-18 days. New eggs were visible forming within the ovary of the mother as early as 2 days following release from the marsupium of the previous clutch of 1st instars. Females produced as many as 3 clutches of 10-22 1st instars, all apparently fertilized by stored sperm from a previous insemination. Development time of S. lerneri is similar to that of another cypridinid, Vargula hilgendorfii, partially reared at a similar temperature, but is much shorter than that of 2 other myodocopids belonging to different families and kept at 12°C or less. Tables and figures showing ontogenetic changes that can be used to identify each instar and a preliminary key to the instars of the Cypridinidae are presented. Most useful characters are the number of bristles on the following limbs: the 4th segment of the 1st antenna, the ventral side of the 2nd segment of the endopodite of the mandible, and the 6th limb; and the number and shape of bristles on the 7th limb. The first 3 instars have a posterior process on the body. Females of the 5th instar and adults are larger than males. Carapace sizes of 5th instar males and adult males from different clutches of the same mother ostracode overlap.

Concentrations of progesterone in milk as a monitor of early pregnancy diagnosis in dairy cows

The objectives of the experiment were to evaluate the efficacy of using progesterone concentrations in milk and palpation per rectum on days 21 or 22 postbreeding to estimate pregnancy and evaluate management practices; and to investigate physiological occurrences leading to incorrect diagnosis of pregnancy when serial samples of milk were collected. Of particular interest were indications of early embyronic death and insemination of cows not in estrus. Milk samples were collected at the afternoon milking of days 0 or 1 (day 0 = day of estrus), 9 or 10, 21 or 22 and 27 or 28 following breeding in 200 lactating dairy cows. Tentative diagnosis of pregnancy was made based on concentrations of progesterone in milk on days 21 and 22 alone and on days 21 or 22 and 27 or 28. In addition all cows were palpated per rectum on days 21 or 22 postbreeding and a tentative pregnancy diagnosis was made. Pregnancy was confirmed by examination of the genital tract per rectum between 35 and 50 days after breeding. Values of 4 ng/ml or greater and/or the presence of a mature corpus luteum were considered positive signs of pregnancy. Progesterone in milk ranged from 0.1 to 18 ng/ml. On days 0 or 1, 9 or 10, 21 or 22 and 27 or 28 concentrations of progesterone in milk averaged 1.5 ± 0.3, 11.1 ± 0.5, 12.0 ± 0.4 12.5 ± 0.5 ng/ml for pregnant cows. Corresponding samples from nonpregnant cows averaged 1.2 ± 0.2, 10.3 ± 0.4, 3.0 ± 0.4, 6.8 ± 0.6 ng/ml, respectively. Ninety-six and 104 cows were classified as pregnant and nonpregnant on days 21 or 22 as compared to 78 and 118 cows diagnosed as pregnant and nonpregnant on days 21 or 22 and 27 or 28 combined. Pregnancy detection by progesterone in milk on days 21 or 22 with pregnancy determined via rectal palpation 35 to 50 days postbreeding was 77 and 100% accurate for positive and negative diagnosis, respectively. The percent agreement using progesterone in milk on days 21 or 22 and 27 or 28 combined was 95 and 100%, respectively, for positive and negative diagnosis. Diagnosis based on rectal palpation 21 or 22 days postbreeding was 63 92 (69%) and 76 88 (87%) for pregnant and nonpregnant cows, respectively. Ten of the 200 cows had progesterone concentratins in milk of > 4 ng/ml at the time of breeding. Six of these cows were pregnant from a previous insemination. The other four cows were nonpregnant and were inseminated during the luteal phase of the cycle. In conclusion, measurement of progesterone in milk is a useful tool in early detection of pregnant and nonpregnant cows and may be useful in detecting reproductive problems in a dairy herd. It will probably be most useful when used in combination with later pregnancy diagnosis per rectum .

Sperm loss at copulation in Culicoides melleus

ABSTRACTThe loss of sperm at copulation in Culicoides melleus was investigated with respect to the previous sexual experience of the female and the interval between her copulations. Approximately 40% of ejaculated sperm were lost if a male copulated with a female within 16 hours of her previous insemination by another male. By 96 hours after the first insemination, sperm transfer at a second copulation was virtually back to the initial 100% level.

Female sexual behavior as the mechanism rendering Aedes aegypti refractory to insemination.

1. Certain females of A. aegypti are refractory to insemination, either because they are too young or because of previous insemination. Earlier reports indicated that refractory females prevent insemination by expulsion of semen from the bursa copulatrix. The present work indicates that this is not the case. 2. Three lines of evidence indicate that refractory females prevent insemination by failing to give the cues that lead to male ejaculation. First, males exposed to refractory females show no loss in their ability to inseminate. Secondly, refractory females exposed to males show no evidence of external sperm masses resulting from expulsion. Thirdly, refractory females placed with radioactive males show no increase in radioactivity, indicating no transfer of labelled semen. Since the forced-copulation technique overrides normal behavior of females, earlier data obtained using this technique are not relevant to normal insemination. 3. Copulation by a mature virgin female is characterized by firm genital union followed by insemination. A refractory female allows the male to couple but not to copulate. Coupling involves a superficial joining of the genitalia; no ejaculation or insemination occurs.

Artificial Production of Monstrosities in the Rabbit

FOUR doe rabbits of unknown breeding were inseminated with the spermatozoa of one male suspended in a solution of 0·1 per cent colchicine in 0·9 per cent sodium chloride. Doe No. 8 gave birth to six normal young and one monster (Fig. 1). No. 13 gave birth to ten normal young; but on the following day was discovered devouring an eleventh, the normality or abnormality of which could not be determined. No. 14 gave birth to eight normal and one monster (Fig. 2). No. 16 gave birth to five normal and one with unclosed anterior fontanelle (Bregma) and with very small philtrum. This lived only five days. The experimental animals gave, therefore, twenty-nine normal young, two definite monsters, one defective young and one uncertain. In previous inseminations the same does had given fifty-nine young without abnormality. Since February, forty does of similar origin but also unknown heredity had produced 425 young from spermatozoa suspended in 0·9 per cent sodium chloride and no abnormalities had been observed.