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PubMed2005

Improvement in embryo recovery using double uterine flushing.

The objective of the present study was to evaluate the effects of double uterine flushing on the recovery of embryos/ova in cattle. Two hundred and ten embryo recovery procedures were conducted using a double uterine flushing method, and the results were compared with 432 conventional single-flushing procedures. Cyclic Limousin (n = 403) and Guzera (n = 239) donor cows received an intravaginal progesterone releasing device and 2 mg of estradiol benzoate on Day 0. Between Days 5 and 9, donors received decreasing doses of FSH, which ranged from 200 to 300 IU (Bos indicus) and 300 to 500 IU (Bos taurus). On the afternoon of Day 7, donors received an injection of 500 microg cloprostenol and progesterone implants were removed 12 h later (morning of Day 8). Artificial insemination was performed between 14 and 26 h after first detection of behavioral estrus. Cows were randomly assigned to have embryos recovered by a double-flushing method (n = 210) or the conventional single-flushing procedure (n = 432). For the double-flushing procedure, after first flushing the whole uterus with 1L of Dubelco's Phosphate Buffered Saline (DPBS), a Foley catheter was positioned in the uterine body to permit refilling of the uterus with fresh DPBS (80-150 mL). The catheter was closed with the plunger of a disposable 5 mL syringe, and the donors were allowed to rest in a holding area for 30 min. Thereafter, a second flush was performed to recover the solution remaining in the uterus. Animals from the control group were subjected to a single uterine flush. From 210 double-flushing procedures, 1409 viable embryos were recovered. In comparison, from 432 cows receiving the single-flushing procedure, 1993 embryos were recovered. Double flushing increased (P < 0.05) the number of embryos recovered per procedure compared to single flushing (6.7 +/- 0.4 versus 4.6 +/- 0.2, respectively; mean +/- S.E.M.). When double flushing was performed, average recovered embryos/ova increased (P < 0.05) from 8.3 +/- 0.4 to 12.7 +/- 0.7 in Limousin and from 7.9 to 11.5 in Guzera. Also, utilization of double flushing increased (P < 0.05) the number of viable embryos from 4.7 +/- 0.3 to 6.9 +/- 0.5 in Limousin and from 4.5 +/- 0.4 to 6.4 +/- 0.7 in Guzera. Mean total embryos/ova was similar (P > 0.05) between the control group and after the first uterine flushing in the double-flushing group; therefore, both flushings were conducted efficiently. In conclusion, double uterine flushing increased embryo recovery in cattle.

Animals↗

PubMed1996

Enhanced growth of mice lacking the cyclin-dependent kinase inhibitor function of p27(Kip1).

SUMMARY: Disruption of the cyclin-dependent kinase-inhibitory domain of p27 enhances growth of mice. Growth is attributed to an increase in cell number, due to increased cell proliferation, most obviously in tissues that ordinarily express p27 at the highest levels. Disruption of p27 function leads to nodular hyperplasia in the intermediate lobe of the pituitary. However, increased growth occurs without an increase in the amounts of either growth hormone or IGF-I. In addition, female mice were infertile. Luteal cell differentiation is impaired, and a disordered estrus cycle is detected. These results reflect a disturbance of the hypothalamic-pituitary-ovarian axis. The phenotypes of these mice suggest that loss of p27 causes an alteration in cell proliferation that can lead to specific endocrine dysfunction.

Animals↗

PubMed1997

A bovine oxytocin transgene in mice: expression in the female reproductive organs and regulation during pregnancy, parturition and lactation.

Transgene bovine oxytocin 3.5 (bOT3.5) consists of the bovine oxytocin structural gene flanked by 0.6 kbp of upstream and 1.9 kbp of downstream sequences. We have examined the expression of bOT3.5 in the female reproductive organs, and we show tissue-specific and physiological regulation dependent on the stage of pregnancy and lactation. In the ovary, no transgene expression could be detected during the estrus cycle, or during pregnancy. However, high levels of transgene RNA were found at day 1 of lactation. Expression dropped 10-fold by day 2 of lactation, and was undetectable thereafter. Interestingly, the expression of bOT3.5 in the mouse ovary at the beginning of lactation mimics that of the endogenous OT gene in the bovine ovary. Expression of the bOT3.5 transgene correlates with a parturition defect that results in considerable maternal mortality.

Animals↗

PubMed1997

GnRH antagonist inhibition of luteinizing hormone secretion and ovulation in the pig.

A GnRH antagonist, Ac-D-p-Cl-Phe1,2, D-Trp3, D-Arg6, D-Ala10 GnRHb (Organon), was utilized to determine the effective dosage and duration to inhibit LH secretion in the pig. In a preliminary trial, barrows received either 10, 50, or 250 micrograms/kg BW of the GnRH antagonist. Secretion of LH was inhibited within 30 min for a duration of 12 h with the 100 micrograms/kg dose but persisted for greater than 48 h with the 250 micrograms/kg treatment. A second study determined effectiveness of the antagonist for inhibiting ovulation in cyclic gilts. At first detection of standing estrus, cyclic gilts were treated with either saline (control), 100, or 200 micrograms/kg BW of the GnRH antagonist (GnRH1). A second group of GnRH antagonist gilts received 200 micrograms/kg BW of the GnRH antagonist approximately 8 h prior to standing estrus (GnRH2). The GnRH1-treatment failed to inhibit or delay ovulation. Ovulation was inhibited and estrous cycles lengthened in GnRH2-treated gilts. These preliminary results suggest that ovulation in the gilt can be inhibited if the GnRH antagonist is administered prior to the LH surge.

Animals↗

PubMed1996

Chronic estrogen-induced cervical and vaginal squamous carcinogenesis in human papillomavirus type 16 transgenic mice.

High-risk human papillomaviruses (HPVs), including type 16, have been identified as factors in cervical carcinogenesis. However, the presence and expression of the virus per se appear to be insufficient for carcinogenesis. Rather, cofactors most likely are necessary in addition to viral gene expression to initiate neoplasia. One candidate cofactor is prolonged exposure to sex hormones. To examine the possible effects of estrogen on HPV-associated neoplasia, we treated transgenic mice expressing the oncogenes of HPV16 under control of the human keratin-14 promoter (K14-HPV16 transgenic mice) and nontransgenic control mice with slow release pellets of 17beta-estradiol. Squamous carcinomas developed in a multistage pathway exclusively in the vagina and cervix of K14-HPV16 transgenic mice. Estrogen-induced carcinogenesis was accompanied by an incremental increase in the incidence and distribution of proliferating cells solely within the cervical and vaginal squamous epithelium of K14-HPV16 mice. Expression of the HPV transgenes in untreated transgenic mice was detectable only during estrus; estrogen treatment resulted in transgene expression that was persistent but not further upregulated, remaining at low levels at all stages of carcinogenesis. The data demonstrate a novel mechanism of synergistic cooperation between chronic estrogen exposure and the oncogenes of HPV16 that coordinates squamous carcinogenesis in the female reproductive tract of K14-HPV16 transgenic mice.

Animals↗

PubMed2003

Evidence for the regulation of glycosylation of golden hamster (Mesocricetus auratus) oviductin during the estrous cycle.

The oviduct contributes to the reproductive environment by secreting various factors, including a family of glycoproteins termed oviductins. Although many studies have demonstrated that ovarian hormones modulate oviductin gene expression in several mammalian species, there has been controversy surrounding the regulation of golden hamster oviductin. The current study was undertaken to investigate the transcriptional and translational modifications of hamster oviductin during the estrous cycle. First, we verified that hamster oviductin mRNA expression remains constant throughout the estrous cycle by semiquantitative reverse transcription polymerase chain reaction. We then developed a polyclonal antibody against recombinant hamster oviductin (rhaOvm). The anti-rhaOvm antibody was subsequently used in conjunction with quantitative immunocytochemistry to investigate the oviductin levels in the hamster oviduct during the estrous cycle. Quantification of immunolabeling revealed a high, consistent level of glycoprotein throughout the estrous cycle. Therefore, it appears that the production of oviductin is not regulated differentially during the estrous cycle. Size variations in hamster oviductin expression were also investigated by Western blot analysis. The oviduct contains several forms of oviductin at each stage of the estrous cycle, the native glycosylated form(s) of 160-350 kDa, and several precursor forms of 70-100 kDa. Although variations in the intensities of the polydispersed band were not evident during the estrous cycle, additional bands ranging from 90 to 100 kDa were detected in the estrus, metestrus, and diestrus 1 stages. The results from the present investigations suggest that whereas ovarian hormones do not appear to influence the hamster oviductin mRNA and protein expressions, glycosylation of hamster oviductin appears to be differentially regulated during the estrous cycle.

Animals↗

PubMed1995

Progesterone, estradiol, and prolactin involvement in lactation, including lactation following a postpartum mating, in the Djungarian hamster (Phodopus campbelli).

The endocrinology of lactation in the Djungarian hamster was investigated through once-daily sampling of females on Days 0, 3, 6, 9, 12, 15, and 18 postpartum. Serum prolactin (PRL) was elevated during early lactation but declined with time. Serum progesterone (P4) levels were uniformly low, and serum estradiol (E2) levels increased after Day 9. New CL were formed after the postpartum ovulation and persisted throughout lactation. During the first 9 days, the CL had the high P4 content typical of pregnancy. After Day 9, each individual CL decreased in P4 content and increased in E2 content. As evidenced by the reappearance of large antral follicles, lactating females probably returned to ovulatory cycles at about that time. The Djungarian hamster has a postpartum estrus and is capable of delivering a second litter without a diapause (18 days), although the majority of second litters are delayed. Mating during the postpartum estrus had no detected effect on growth or survival of the first litter. Second pregnancies were developmentally delayed by 3 to 7 days. P4 was effectively absent from serum for the first 12 days after mating. Although CL contained high levels of P4, the CL remained small and poorly vascularized. Mated females did not have higher serum P4 levels than nonpregnant, lactating females until Day 18. In response to the competing demands of lactation and concurrent gestation, the endocrine conditions associated with pregnancy were the most affected.

Animals↗

PubMed1975

Synthesis and inducibility of the Uterine estrogen-induced protein, IP, during the rat estrous cycle: clues to uterine estrogen sensitivity.

Analysis of newly labeled soluble proteins in uteri of mature rats throughout the estrous cycle indicates that the relative rate of synthesis of the uterine estrogen-induced protein, IP, is high at proestrus, when endogenous estrogen secretion is maximal; it is not synthesized at detectable levels at estrus and metestrus; and some minimal synthesis is seen in diestrus uteri. Injection of exogenous estrogen results in some increase in the IP synthesis rate at proestrus; slight induction of IP synthesis at estrus; and maximal induction (as great as that induced in the mature, ovariectomized uterus by estrogen) at metestrus and diestrus. Studies in the immature (day 21-24) rat, aimed at determining the possible causes of the uterine recalcitrance to exogenous estrogen seen at estrus, indicate that one can reproduce in the immature uterus a period of feeble responsiveness to a second injection of estrogen after exposure to a first, high dose of estrogen. After a single injection of estrogen, there is a lag between the gradual return of full IP inducibility (requiring over 40 hours to reach the control level) and the return of nuclear-translocatable receptor (at control level by 24 hr). This suggests that in addition to the presence of nuclear-translocatable receptor, the response to a second injection of estrogen is dependent upon other factors whose replenishment and/or reactivation is slower than that of the receptor.

Age Factors↗

PubMed1995

Anti-müllerian hormone and anti-müllerian hormone type II receptor messenger ribonucleic acid expression in rat ovaries during postnatal development, the estrous cycle, and gonadotropin-induced follicle growth.

During fetal development, anti-müllerian hormone (AMH) is produced only by Sertoli cells, but postnatally, granulosa cells also produce this peptide growth/differentiation factor. We recently identified a candidate AMH type II receptor (AMHRII). In the present study, postnatal ovarian AMH and AMHRII messenger RNA (mRNA) expression was studied by in situ hybridization and ribonuclease protection. In ovaries from adult rats, AMH and AMHRII mRNAs were found to be mainly expressed in granulosa cells from preantral and small antral follicles. Corpora lutea and large antral follicles express little or no AMH and AMHRII mRNA, and primordial follicles and oocytes appeared to be AMH and AMHRII mRNA negative. Thecal and interstitial cells express no detectable AMH mRNA and little or no AMHRII mRNA. The colocalization of AMH and AMHRII mRNAs in granulosa cells of specific follicle types suggests that actions of AMH via AMHRII are autocrine in nature. There is a decreased level of AMH and AMHRII mRNA expression when follicles become atretic. Both mRNA species are eventually lost from atretic follicles, although AMHRII mRNA expression seems to persist somewhat longer than AMH mRNA. During the estrous cycle, no marked changes in the patterns of AMH and AMHRII mRNA expression were detected, except at estrus, when expression of both mRNA species in preantral follicles was decreased compared to that on the other days of the cycle. On postnatal day 5, total ovarian AMH mRNA expression is low and is located in small preantral follicles. During the first weeks of postnatal development, AMH mRNA expression in preantral follicles increases, and the later formed small antral follicles also express AMH mRNA. In contrast, AMHRII mRNA is expressed on postnatal day 5 at a higher level than AMH mRNA, but cannot be localized to specific cell types. From postnatal day 15 onward, AMHRII mRNA expression becomes more restricted to the preantral and small antral follicles. Treatment of prepubertal rats with GnRH antagonist (Org 30276) and human recombinant FSH (Org 32489) or with GnRH antagonist and estradiol benzoate resulted in follicle growth and inhibition of AMH and AMHRII mRNA expression in some, but not all, preantral and small antral follicles. These results indicate that FSH and estrogens may play a role in the down-regulation of AMH and AMHRII mRNA expression in vivo when small antral follicles differentiate into large antral follicles. Furthermore, the FSH surge on the morning of estrus may inhibit AMH and AMHRII mRNA expression in preantral follicles.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2004

Ability of intravaginal progesterone inserts and melengestrol acetate to induce estrous cycles in postpartum beef cows.

Postpartum anestrous interval in beef cows is a major factor contributing to reproductive failure during a defined breeding season. Our objectives were to determine the ability of a controlled internal drug-releasing device (CIDR, 1.9 g of progesterone), a normal dose of melengestrol acetate (MGA, 0.5 mg x cow(-1) x d(-1)), or a high dose of MGA (4.0 mg x cow(-1) x d(-1)) to induce ovulation and to eliminate short estrous cycles. Multiparous beef cows (n = 100) were equally assigned to one of four treatments: CIDR, normal MGA, high MGA, or control by age, days postpartum, body condition, and body weight. All cows were fed carrier (0.9072 kg x cow(-1) x d(-1)) with (normal MGA, 0.55 mg/kg; high MGA, 4.41 mg/kg) or without MGA for 7 d (d -6 to 0). On d -6, CIDR were inserted and then removed on d 0. Estrous behavior was monitored continuously from d -6 until 29 using HeatWatch electronic mount detectors. Blood was collected on d -13, and three times weekly from d -6 to 29. Treatment influenced (P = 0.03) the percentage of cows that were detected in standing estrus. Beginning on d 2, more CIDR-treated cows had exhibited standing estrus compared with high MGA-treated or control cows, but CIDR- and normal MGA-treated cows did not differ. The percentage of CIDR-treated cows that had ovulated was greater (P < 0.05) than the percentage of normal MGA-treated, high MGA-treated, or control cows beginning on d 4. The percentage of cows that exhibited standing estrus before the first postpartum ovulation (CIDR = 65%, normal MGA = 57%, high MGA = 35%, control = 30%) did not differ (P = 0.09) among treatments. Luteal life span following the first ovulation postpartum and the percentage of cows with a normal luteal life span (i.e., progesterone > 1 ng/mL for > or = 10 d) was greater (P < 0.01) in CIDR-treated cows (14.0 +/- 0.8 d; 20/20, 100%) compared with normal MGA-treated (6.2 +/- 1.0 d; 3/13, 23%), high MGA-treated (9.6 +/- 1.0 d; 8/14, 57%), or control cows (6.1 +/- 0.9 d; 4/17, 24%), and greater (P < 0.03) in high MGA-treated cows than in normal MGA-treated or control cows. In the present study, treatment of early postpartum suckled beef cows with CIDR induced ovulation and initiated estrous cycles with a normal luteal life span in more cows than did treatment with MGA. Treatment with MGA (normal or high dose) did not induce ovulation earlier than in control cows, but a high dose of MGA increased the percentage of cows with normal luteal life spans following the first ovulation postpartum.

Administration, Intravaginal↗

PubMed2006

Relationship between size of the ovulatory follicle and pregnancy success in beef heifers.

Previous research indicated that the size of the ovulatory follicle at the time of insemination significantly influenced pregnancy rates and embryonic/fetal mortality after fixed-timed AI in postpartum cows, but no effect on pregnancy rates was detected when cows ovulated spontaneously. Our objective was to evaluate relationships of fertility and embryonic/fetal mortality with preovulatory follicle size and circulating concentrations of estradiol after induced or spontaneous ovulation in beef heifers. Heifers were inseminated in 1 of 2 breeding groups: (1) timed insemination after an estrous synchronization and induced ovulation protocol (TAI n = 98); or (2) AI approximately 12 h after detection in standing estrus by electronic mount detectors during a 23-d breeding season (spontaneous ovulation; n = 110). Ovulatory follicle size at time of AI and pregnancy status 27, 41, 55, and 68 d after timed AI (d 0) were determined by transrectal ultrasonography. Only 6 heifers experienced late embryonic or early fetal mortality. Interactions between breeding groups and follicle size did not affect pregnancy rate (P = 0.13). Pooled across breeding groups, logistic regression of pregnancy rate on follicle size was curvilinear (P < 0.01) and indicated a predicted maximum pregnancy rate of 68.0 +/- 4.9% at a follicle size of 12.8 mm. Ovulation of follicles < 10.7 mm or > 15.7 mm was less likely (P < 0.05) to support pregnancy than follicles that were 12.8 mm. Ovulatory follicles < 10.7 mm were more prevalent (28% of heifers) than ovulatory follicles > 15.7 mm (4%). Heifers exhibiting standing estrus within 24 h of timed AI had greater (P < 0.01) follicle diameter (12.2 +/- 0.2 mm vs. 11.1 +/- 0.3 mm) and concentrations of estradiol (9.9 +/- 0.6 vs. 6.6 +/- 0.7) and pregnancy rates (63% vs. 20%) than contemporaries that did not exhibit behavioral estrus. However, when differences in ovulatory follicle size were accounted for, pregnancy rates were independent of expression of behavioral estrus or circulating concentration of estradiol. Therefore, the effects of serum concentrations of estradiol and behavioral estrus on pregnancy rate appear to be mediated through ovulatory follicle size, and management practices that optimize ovulatory follicle size may improve fertility.

Animals↗

PubMed1992

Accessory sperm numbers for cattle inseminated with protamine sulfate microcapsules.

A study utilizing two morphologically distinct sperm populations in a heterospermic trial was conducted to evaluate the effect of microencapsulation on accessory sperm number in artificially inseminated cattle. Inseminates consisted of an equal number (100 x 10(6) of morphologically normal and tapered sperm. In reciprocal inseminates, one of the two sperm types was encapsulated in protamine sulfate microcapsules, and the other type was unencapsulated. Insemination of both sperm types that were unencapsulated served as the control. Thirty-one embryos were nonsurgically recovered 6 d postinsemination, and accessory sperm within the zona pellucida were counted and morphologically classified as normal or tapered. Microencapsulated sperm contributed 25.7% of the accessory sperm obtained for inseminates containing microcapsules. Microencapsulation did not affect the total number of accessory sperm per embryo; however, encapsulation did reduce accessory sperm for the specific sperm type encapsulated. The proportion of morphologically normal to total accessory sperm recovered were 65.8% when both sperm types were unencapsulated, 35.4% when normal sperm were encapsulated, and 80.6% when the tapered sperm were encapsulated. High accessory sperm numbers per embryo were related to embryo quality (P less than .01). Mean accessory sperm and standard deviations for degenerate embryos and for embryos classified fair to poor, good, and excellent were 1.7 +/- 2.9, 11.1 +/- 8.6 24.9 +/- 33.9, and 84.3 +/- 58.3. We conclude that sperm inseminated in protamine sulfate microcapsules can be released and can attach to the zona pelucida of ova in vivo. Microencapsulation failed to increase accessory sperm numbers under conditions of this experiment in which insemination was 12 h after estrus was first detected.

Animals↗

PubMed1993

Factors affecting fertility in the postpartum cow: role of the oocyte and follicle in conception rate.

Four experiments were designed to examine the contribution of the oocyte or the follicular, oviductal, or early uterine environments to low fertility associated with the first ovulation postpartum. At 17-25 days postpartum in experiments 1, 2, and 3, suckled beef cows were assigned at random to receive 6 mg norgestomet, via ear-implant, for 9 days (NOR) or to serve as controls (CON). Calves were weaned from all cows 7 days after assignment to treatment in order to induce estrus, an LH surge, ovulation, and subsequent formation of CL. As cows were detected to be in estrus, they were bred first by natural service and 12 h later by artificial insemination. In experiment 1, on Day 3 after estrus, the oviduct ipsilateral to the side of ovulation was removed and flushed for recovery of an embryo or oocyte. Rates of recovery (86%), fertilization (68%), and development of fertilized oocytes to the 4- to 8-cell stage (100%) did not differ between CON and NOR cows. In experiment 2, uteri were flushed nonsurgically on Day 6 after estrus. Rates of recovery of embryos from the uterus were similar between CON (86%) and NOR (71%) cows. In experiment 3, one half of the cows in each group (CON and NOR) were fed melengestrol acetate (MGA) beginning on Day 4 after estrus and continuing until Day 35. The remaining cows in each group served as controls. Treatment with NOR increased (p < 0.05) the proportion of cows that maintained pregnancy until Day 35 (9/22) as compared to controls (0/18).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Electrophoretic characterization of equine oviductal fluid.

To characterize further the events involved in fertilization and early embryonic development in the mare, effect of the estrous cycle on oviductal fluid proteins was investigated. Five mares had indwelling cannulas placed in their oviducts so that fluid could be collected throughout the estrous cycle. Daily fluid volumes were recorded and mares were monitored for signs of standing estrus. Oviductal fluid samples were pooled across mares according to stage of cycle (either estrus or nonestrus) for further analysis. Two-dimensional polyacrylamide gel electrophoresis (PAGE) was used to determine proteins present in estrus-associated and nonestrus-associated equine oviductal fluid as compared to blood serum from the same mares. Oviductal fluid volumes increased significantly during estrus to an average of 3.94 ml/24 hr from 1.44 ml/24 hr during nonestrus. Total oviductal protein increased significantly from 24.6 mg/24 hr during nonestrus to 53.9 mg/24 hr during estrus. One-dimensional PAGE demonstrated that the proteins in equine oviductal fluid were present throughout the cycle and also common to equine serum. Reducing conditions revealed one band at 106 kDa detected only in nonestrus-associated oviductal fluid, while nonreducing conditions revealed bands at 48 and 25 kDa that were present in oviductal fluid in general. Two-dimensional PAGE demonstrated three 50 kDa proteins that were detected only in estrus-associated oviductal fluid and several 24 kDa proteins detected only in nonestrus-associated oviductal fluid. Those proteins found only in estrus-associated oviductal fluid may be vital to the fertilization process, while those found only in nonestrus-associated oviductal fluid may be vital to early embryonic development.

Animals↗

PubMed1987

Relationships between time of day, estrous behavior, and the preovulatory luteinizing hormone surge in Holstein cows after treatment with cloprostenol.

Using continuously observed primiparous cows, comparisons were made between cloprostenol-induced and preceding or succeeding spontaneous estruses in a crossover design. There were no significant differences between spontaneous and induced estruses in duration or intensity. In a second experiment, estrus was controlled by administration of two cloprostenol injections, 12 h apart, initiated at 0800 or 2000 h during the midluteal phase. Continuous observation and frequent blood sampling were used to determine relationships between behavior and plasma concentrations of LH and estradiol-17 beta. Relationships between plasma concentrations of estradiol-17 beta and the intensity or duration of estrous behavior were not detected. The intervals from treatment to the onset of estrus and to the LH surge were not affected by time of treatment but were highly correlated. The onset of the LH surge always followed the onset of standing to be mounted by 1 to 2 h. Initiating treatment with cloprostenol at 2000 h resulted in an increased proportion of animals exhibiting onset of estrus and increased mounting behavior at night relative to treatment at 0800 h. For efficient detection of estrus after cloprostenol treatment it is suggested that cloprostenol be administered early in the working day.

Animals↗

PubMed2003

Design and performance of statistical process control charts applied to estrous detection efficiency.

Statistical process control (SPC) charts to monitor production processes have not been widely used in dairy management. Shewhart and cumulative sum (cusum) control charts were designed to determine true changes in estrous detection efficiency (EDE) amidst normal variation in dairy cattle. A stochastic simulation model was used to track performance over time of individual cows in herds of 100 and 1000 cows. Estrous detection ratios (EDR), calculated as observed estruses divided by estimated estrous days (in periods of 1 to 60 d), were used to monitor EDE. Control charts for EDR, using normal and binomial distributions, were designed at 0.65 EDE for both herd sizes; then EDE was set to 0.65 (no change), 0.55, 0.45, or 0.35 and average days to the first detection signal (ATS) in 400 runs was determined. Observed ATS at 0.65 EDE could differ from the target ATS, depending on the SPC chart design and estimated proportions of estrous days for inseminated cows. Observed ATS were shorter for larger changes in EDE and for the 1000-cow herd. Observed ATS for a change to 0.55 EDE were approximately 300 d (100 cows) or 60 d (1000 cows) with the cusum charts. For a change to 0.35 EDE, observed ATS were approximately 50 d (100 cows) and approximately 11 d (1000 cows). Shewhart charts performed similarly or took longer to signal changes depending on period length. Observed ATS on cusum charts were much longer than minimum when non-optimal reference values were used in the design. Observed ATS were also longer when SPC charts were designed with a longer target ATS and change in EDE was small. Control charts using normal and binomial distributions generally performed similarly. Statistical process control charts detected changes in estrous detection efficiency soon enough to be potentially useful in dairy management.

Animals↗

PubMedDate not supplied

Cyclic changes in the expression of endometrial proteins of the mouse during the normal estrus cycle.

Cellular proteins extracted from the endometrial tissue of normal sexually mature outbred mice were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to define the changes in protein expression that occur during the normal estrus cycle. Using one dimensional gradient SDS-PAGE it was possible to resolve approximately 80 protein bands, 8 of which showed cyclic changes. Five protein bands (Mr 28, 40, 135, 150 and 220 kD) were most prominent in the estrus phase and were barely detectable or not visible at all in the diestrus phase. Since the estrus phase is under the influence of estrogen, these five proteins were considered to be estrogen-induced. Two protein bands (Mr 35, and 37 kD) were more prominent in the diestrus phase. The 116 kD protein band was found only in the diestrus phase. These three proteins were considered to be induced by progesterone, the hormone that governs the diestrus phase of the cycle. None of the protein bands was found to be typical of the proestrus and metestrus phases of the cycle, although the 28 kD band appeared more prominent in proestrus than in other phases. These data show that the mouse estrus cycle is associated with phase-specific changes which can be reproducibly and reliably detected by SDS-PAGE.

Animals↗

PubMed1979

Estrous cycle patterns in cattle monitored by electrical resistance and milk progesterone.

An electronic probe with parallel stainless steel electrodes was designed to measure changes in electrical resistance in the anterior vagina associated with increased cervical mucus secretion at estrus. Three groups of Holsteins were probed, and a sample of residual milk after milking was taken for progesterone assay every 2nd day for 28 to 40 days. Group I consisted of 29 cycling virgin heifers, Group II consisted of 24 lactating cows in the Cornell herd, and Group III consisted of 62 lactating cows in three commercial herds. Lactating cows were 26 or more days postpartum when sampling began. In Group I, 77% of the measurements at the ventral surface of the anterior vagina were lowest on the day of estrus and correlated well with days KaMaR Heatmount Detectors were triggered or chalk was erased. In Groups II and III, average electrical resistance also was minimal at estrus and was correlated .92 to .99 with average milk progesterone during the 4 days preceding and including estrus. The electronic probe appears to enable one to detect which cows are cycling normally and to aid in determining when to expect estrus.

Animals↗