Estrous expression during a fixed-time artificial insemination protocol enhances development and interferon-tau messenger RNA expression in conceptuses from Bos indicus beef cows

Expression of estrus (EST) near the time of fixed-time artificial insemination (FTAI) increases pregnancy success in beef females. This outcome has been associated with improved pregnancy establishment and maintenance, although research is still warranted to validate this theory. Hence, this experiment compared ovarian, uterine and conceptus factors associated with pregnancy establishment in Bos indicus beef cows according to estrous expression during a FTAI protocol. One hundred lactating multiparous Nelore cows received a 2 mg injection of estradiol benzoate and an intravaginal progesterone (P4) releasing device on day −11, a 12.5 mg injection of prostaglandin F_2α on day −4, P4 device removal in addition to 0.6 mg injection of estradiol cypionate and 300 IU injection of equine chorionic gonadotropin on day −2, and FTAI on day 0. An estrous detection patch was attached to the tailhead of each cow on day −2, and estrous expression was defined as removal of >50% of the rub-off coating from the patch at FTAI. Overall, 39 cows expressed EST, 55 did not express EST (NOEST), and six cows lost their patch and were discarded from the experiment. Ovarian ultrasonography was performed at FTAI, and on days 7 and 15 of the experiment. Blood samples were also collected on days 7 and 15. Only cows without a corpus luteum (CL) on day 0, and with a CL on days 7 and 15 remained in the experiment (EST, n=36; NOEST, n=48). On day 15, cows were randomly selected within each group (EST, n=29; NOEST, n=30) for conceptus collection via transcervical flushing, followed by endometrial biopsy in the uterine horn ipsilateral to the CL. Within cows not assigned to conceptus collection, blood samples were collected for whole blood RNA extraction (day 20) and pregnancy status was verified by transrectal ultrasonography (day 30). Diameter of dominant follicle on day 0 and plasma P4 concentrations on day 7 were greater (P⩽0.02) in EST v. NOEST cows. Conceptus length and messenger RNA (mRNA) expression of prostaglandin E synthase and interferon-tau were greater (P⩽0.04) in EST v. NOEST cows. Moreover, EST cows diagnosed as pregnant on day 30 had greater (P<0.01) blood mRNA expression of myxovirus resistance 2 on day 20 compared with NOEST. In summary, estrous expression near the time of FTAI enhanced pregnancy establishment factors in B. indicus cows, including conceptus development and mRNA expression of interferon-tau.     

Endothelial vasodilator production by uterine and systemic arteries. IV. Cyclooxygenase isoform expression during the ovarian cycle and pregnancy in sheep

Uterine artery endothelial production of the potent vasodilator, prostacyclin, is greater in pregnant versus nonpregnant sheep and in whole uterine artery from intact versus ovariectomized ewes. We hypothesized that uterine artery cyclooxygenase (COX)-1 and/or COX-2 expression would be elevated during pregnancy (high estrogen and progesterone) and the follicular phase of the ovarian cycle (high estrogen/low progesterone) as compared to that in luteal phase (low estrogen/high progesterone) or in ovariectomized (low estrogen and progesterone) ewes. Uterine and systemic (omental) arteries were obtained from nonpregnant luteal-phase (LUT; n = 10), follicular-phase (FOL; n = 11), and ovariectomized (OVEX; n = 10) sheep, as well as from pregnant sheep (110-130 days gestation; term = 145 +/- 3 days; n = 12). Endothelial and vascular smooth muscle (VSM) COX-1 protein levels and uterine artery endothelial cell COX-1 mRNA levels were compared. Using immunohistochemistry and Western analysis, the primary location of COX-1 protein was the endothelium; that is, we observed 2.2-fold higher COX-1 protein levels in intact versus endothelium-denuded uterine artery and a 6.1-fold higher expression in the endothelium versus VSM (P < 0.05). COX-2 protein expression was not detectable in either uterine artery endothelium or VSM. COX-1 protein levels were observed to be higher (1.5-fold those of LUT) in uterine artery endothelium from FOL versus either OVEX or LUT nonpregnant ewes (P < 0.05), with substantially higher COX-1 levels seen in pregnancy (4.8-fold those of LUT). Increases in uterine artery endothelial COX-1 protein were highly correlated to increases in the level of COX-1 mRNA (r(2) = 0.66; P < 0.01) for all treatment groups (n = 6-8 per group), suggesting that increased COX-1 protein levels are regulated at the level of increased COX-1 mRNA. No change in COX-1 expression was observed between groups in a systemic (omental) artery. In conclusion, COX-1 expression is specifically up-regulated in the uterine artery endothelium during high uterine blood flow states such as the follicular phase and, in particular, pregnancy.     

Treatment of dairy cows with PGF2alpha or NSAID, in combination with antibiotics, in cases of postpartum uterine inflammation

ABSTRACT: BACKGROUND: The aim of the study was to test the effect of two treatments in cases of acute puerperal metritis (APM) and clinical metritis (CM). METHODS: Cows with APM and CM (n = 40)) were matched according to plasma fibrinogen levels (Fb) into three groups. Two negative control groups D (n = 11) and E (n = 17) were composed of healthy cows. The proportion of animals with APM and CM was similar within the groups. Treatment was started on the 3rd day postpartum (PP). In group A (n = 15), intramuscular (i.m.) administration of ceftiofur was used for five days in combination with flunixin for three days. Group B (n = 15) received i.m. administration of ceftiofur for five days followed by two injections of prostaglandin F2alpha, with an interval of 8 h, on the 8th day PP. Group C (n = 10) served as a control group with no treatment. The general health status, body temperature (BT) and vaginal discharge were evaluated daily. Endometrial biopsies for bacteriology were taken once a week for seven weeks PP. Blood samples for the analysis of acute phase proteins were collected once a week for six weeks PP. Samples for progesterone analysis were taken twice a week for seven weeks PP. Fertility performance data were recorded. RESULTS: The area under the curve of BT was higher in group B than in group D cows (P < 0.05). No differences were found for vaginal discharge. There were no differences in bacterial growth, start of ovarian activity or serum amyloid-A or fibrinogen levels among the groups. The haptoglobin concentration was higher in the first and second weeks PP in group B compared with the other groups (P < 0.05). The number of days open was higher in group A than in both groups B and D (P < 0.05). The pregnancy rate after the first two services was higher (P < 0.05) in groups B and D than in groups A and C. The number of services per pregnancy was lower in group B than in group C (P < 0.05). CONCLUSIONS: Regardless of more severe uterine inflammation found in animals from group B, these cows showed the same fertility parameters as healthy animals.     

Evaluation of cytokine expression by blood monocytes of lactating Holstein cows with or without postpartum uterine disease

Whereas neutrophils are the main phagocytic leukocytes, monocytes and macrophages are actively involved in immunomodulation after infection. Recent studies have demonstrated that neutrophil function is impaired by the state of negative energy balance around parturition, and that cows that develop uterine disease have a greater degree of negative energy balance than healthy cows. The objectives of this study were to compare monocyte gene expression and protein secretion of selected cytokines from calving to 42 d after calving in Holstein cows that did or did not develop uterine disease. Real time quantitative RT-PCR (Tumor necrosis factor-α (TNFα), Interleukin (IL)-1β, IL-6, IL-8 and IL-10) and ELISA (TNFα, IL-1β and IL-8) were used to evaluate cytokine response following in vitro stimulation of blood-derived monocytes with irradiated E. coli. Relative to unstimulated cells, E. coli-stimulated monocytes from cows with metritis had lower gene expression of key pro-inflammatory cytokines than healthy cows from calving to 14 d after calving (TNFα at 0, 7, and 14 d after calving, IL-1β and IL-6 at 7 and 14 d after calving; P < 0.05). There were no significant differences between groups for expression of IL-8 or the anti-inflammatory cytokine IL-10. This was due, in part, to higher gene expression in unstimulated monocytes (TNFα, IL-1β, IL-6 and IL-10) in early lactation from cows with metritis. Expression of mRNA in stimulated cells (relative to housekeeping genes) was lower for TNFα (7 and 14 d postpartum) and for IL-10 (7 and 14 d postpartum) in cows with metritis. Concentration of TNFα was lower in the culture medium of E. coli-stimulated monocytes from cows with metritis than healthy cows at calving and 7 and 21 d after calving (P < 0.05). Circulating cytokine concentrations were not different between groups for IL-8 and were below the limits of detection for TNFα and IL-1β. Cytokine gene expression and production were similar between healthy cows and cows that developed endometritis, diagnosed cytologically at 42 d after calving. We concluded that altered levels of expression and production of pro-inflammatory cytokines postpartum could contribute to impaired inflammatory response and predispose cows to development of metritis.     

Synchronization of parturition in beef cattle using delay as well as induction

Two methods for synchronization of parturition in beef cattle were examined. In the first experiment, four groups of cows and heifers were used: untreated (C, n=9), 10 mg flumethasone on day 281 of gestation (F, n=9), 100 mg progesterone daily from days 276 through 283 and 50 mg progesterone on day 284 (P, n=6), and (P + F on day 284, n=7). Variances in gestation lengths (C, 26.01; F, 0.77; P, 11.97; P + F, 1.93) and proportions of cows and heifers with retained placentas (C, 0 9 ; F, 4 9 ; P, 1 6 ; P + E, 0 7 ) differed significantly among groups. Differences among groups in calving difficulty scores and proportions of dead calves were not significant. Four of the thirteen cows and heifers treated with progesterone required assistance in calving and all four delivered dead calves. Pulling of these calves was not accompanied by uterine contractions. Conversely, the difficult calvings in the control- and flumetha-sone-treated cows and heifers were accompanied by uterine contractions. In the second experiment, two groups of cows were used: 1) a single injection of 20 mg dexamethasone on either day 276, 277 or 278 followed by injections of saline every 12 h for 2.5 additional days (n=6), and 2) repeated injections of 20 mg dexamethasone every 12 h for 3 days beginning on day 276, 277 or 278 (n=8). The interval from time of first treatment to calving was not different between groups (43.6 and 43.0 h, respectively). Differences between calving difficulty scores, proportions of dead calves and incidence of retained placentas were not significant. Induction very close to the expected calving date could reduce the problems of retained placenta; however, methods must be identified to safely delay parturition.     

Strategic use of gonadotrophin-releasing hormone (GnRH) to increase pregnancy rate and reduce pregnancy loss in lactating dairy cows subjected to synchronization of ovulation and timed insemination

The objective of this study was to determine the effect of GnRH (100 microg i.m.) treatment 5 and 15 days after timed insemination (TAI) on pregnancy rate and pregnancy loss in lactating dairy cows subjected to synchronization of ovulation. The study included 831 lactating dairy cows subjected to a Presynch-Ovsynch protocol for first service. On the day of TAI (Day 0), cows were randomly assigned to one of four experimental groups. Cows in Group 1 (n = 214) were treated with GnRH on Day 5; cows in Group 2 (n = 209) were treated with GnRH on Day 15; cows in Group 3 (n = 212) were treated with GnRH on both Day 5 and Day 15; cows in Group 4 (n = 196) were not treated. Pregnancy rate was evaluated at Day 27 and Day 45 after TAI. The interestrus interval and the proportion of cows diagnosed not pregnant based on expression of estrus and insemination before pregnancy diagnosis on Day 27 were determined. The results of this study are: (1) GnRH treatment on Day 5 or Day 15 did not increase pregnancy rate, or reduce pregnancy loss between Day 27 and Day 55 after TAI; (2) cows treated with GnRH on both Day 5 and Day 15 had a lower (P < 0.01) proportion of cows diagnosed not pregnant based on expression of estrus before ultrasonography on Day 27 (26.5%) compared to control cows (52.9%), and these cows had an extended (P = 0.05) interestrus interval (23.4 days vs. 21.5 days); and (3) GnRH treatment on both Day 5 and Day 15 after TAI reduced pregnancy rate on Day 27 (36.8% vs. 44.4% for control cows; P < 0.03) and Day 55 (28.3% vs. 36.2% for control cows; P < 0.01). Therefore, strategies to stimulate CL function using multiple doses of GnRH during the luteal phase need to consider potential negative effects.     

Effect of administration of eCG to postpartum cows on folliculogenesis in the ovary ipsilateral to the previously gravid uterine horn and uterine involution

This study tested the hypothesis that increased oestradiol secretion by large follicles in the ovary ipsilateral to the previously gravid uterine horn has a local effect to increase the rate of uterine involution. Cows were administered an i.m. water placebo (n = 19), 250 iu equine chorionic gonadotrophin (eCG) (n = 18) or 750 iu eCG (n = 20) 14 days post partum (day 0). Transrectal ultrasonography at the time of treatment and 2, 4 and 6 days later monitored uterine horn diameter and ovarian structures. Blood samples collected contemporaneously were assayed for 15-keto-13, 14-dihydro-prostaglandin F(2alpha) and oestradiol concentration. For control cows, accumulated diameter of the largest follicle in the ovary ipsilateral to the previously gravid uterine horn, compared with the contralateral ovary, was smaller on day 0 (P < 0.05) and days 2, 4 and 6 (P < 0.001). There were no significant differences in the eCG-treated animals. There were 12, 8 and 11 cows with a plasma oestradiol concentration < 1 pg ml(-1) on day 0 in the control, 250 and 750 iu eCG treatment groups, respectively. For control cows, the peripheral oestradiol concentrations were higher on day 6 compared with days 0, 2 and 4 (P < 0.05); for cows treated with 250 iu eCG, concentrations were higher on days 4 and 6 compared with day 0 (P < 0.05); and for cows treated with 750 iu eCG, concentrations were higher on days 2 and 4 compared with day 0 (P < 0.01). Treatment with eCG, or the presence of a follicle > 8 mm in diameter in the ovary ipsilateral to the previously gravid uterine horn, did not affect the rate of uterine involution or plasma 15-keto-13,14-dihydro-prostaglandin F(2alpha) concentration. In conclusion, administration of eCG to increase follicular growth and oestradiol production overcame the inhibition of follicular growth in the ovary ipsilateral to the previously gravid uterine horn, but did not affect uterine involution.     

Timed artificial insemination plus heat II: gonadorelin injection in cows with low estrus expression scores increased pregnancy in progesterone/estradiol-based protocol

The use of tail chalk and estrus/heat expression scores (HEATSC) evaluation is instrumental in identifying cows with greater estrus expression and greater artificial insemination pregnancy rates (P/AI) in cows submitted to timed artificial insemination (TAI), and cows with low or no estrus expression present lower P/AI. It was intended in this study to improve the pregnancy rates in TAI for Bos indicus beef cows, and gonadotrophin-releasing hormone (GnRH) injection was hypothesized to increase pregnancy rates in a TAI program for cows submitted to progesterone–estradiol-based protocols with low or no estrus expression, evaluated by HEATSC. Cows (n= 2284) received a progesterone device and 2 mg estradiol benzoate, after 8 days the device was removed and 1 mg estradiol cypionate, 150 μg of d-cloprostenol and 300 IU equine chorionic gonadotropin was administered. All cows were marked with chalk and HEATSC evaluated (scales 1 to 3) at TAI performed on day 10. Animals with HEATSC1 and HEATSC2 (n= 937) received 100 μg de gonadorelin (GNRH group; n= 470), or 1 ml saline (Control group; n= 467), and cows with HEATSC3 (named HEAT group; n= 1347) received no additional treatment. The larger dominant follicle, evaluated on day 8and at TAI (day 10), was greater in HEAT group (P= 0.0145 and P <0.001, respectively). Corpus luteum (CL) area and progesterone concentration was evaluated on day 17, and CL area was larger in HEAT group, intermediary in Control and lower in GnRH group (Control= 2.68 cm², GnRH= 2.37 cm², HEAT group= 3.07 cm², P <0.001). Greater progesterone concentrations were found in HEAT group than in Control and GnRH groups (Control= 4.74 ng/ml, GnRH= 4.29 ng/ml, HEAT group= 6.08 ng/ml, P<0.001). There was a difference in ovulation rate, greater in HEAT group than GnRH and Control groups (Control= 72.5%; GnRH= 81.25%; HEAT group= 90.71%; P= 0.0024). Artificial insemination pregnancy rates was greater in HEAT group (57.09% (769/1347) than in Control and GNRH groups, with positive effect of GnRH injection at the time of TAI in P/AI (Control= 36.18% (169/467), GnRH= 45.95% (216/470); P<0.0001). In conclusion, GnRH application in cows with low HEATSC (1 and 2) is a simple strategy, requiring no changes in TAI management to increase pregnancy rates in postpartum beef cows submitted to progesterone–estradiol-based TAI protocols, without reaching, however, the pregnancy rates of cows that demonstrate high estrus expression at the TAI.     

Relationship between peripheral estrogen concentrations at insemination and subsequent fetal loss in cattle

In a survey on pregnancy rate and embryonic losses in dairy cattle on 6 Israeli farms, cows (n = 78) were divided into 3 groups on the basis of ultrasonography at 21 d post insemination; pregnancy diagnosis at 40 to 50 d post insemination and blood progesterone (P4) levels at 21 d. The groups were either pregnant (P4 level > 1.0 ng/ mL); not pregnant (P4 < 0.5 ng/mL), or showed early embryo loss (P4 > 1.0 ng/mL and the presence of an embryonic vesicle on D 21 but later returned to estrus or were found not pregnant on D 40 to 50). On the day of insemination, peripheral estrogen was significantly higher (P < 0.05) in the early embryo loss group (15.3 +/- 1.1 pg/mL, n = 27) than in pregnant (9.4 +/- 0.6 pg/mL, n = 26) or not pregnant (9.6 +/- 0.7 pg/mL, n = 25) group. The cows on 3 farms which were fed 1 to 2 kg/d of vetch (Vicia sativa), an estrogenic legume, had higher estrogen concentrations on the day of insemination than cows (2 farms) fed other legumes (13.7 +/- 0.64, n = 58 vs 10.7 +/- 0.8 pg/mL, n = 42; P < 0.01). On one of the 3 farms, vetch was replaced with alfalfa after the first year. Following the cessation of vetch feeding the estrogen concentrations in the blood decreased from 32 +/- 5 pg/mL to 14 +/- 2 pg/mL (n = 9). These data suggest that high peripheral estrogen on the day of insemination is associated with early embryonic loss. These data also indicate that estrogen concentrations on the day of insemination can be influenced by diet.     

Transrectal Doppler sonography of uterine blood flow in cows during pregnancy

Transrectal Doppler ultrasound was used for the noninvasive investigation of uterine blood flow in three cows during pregnancy. The uterine arteries ipsi and contralateral to the conceptus were scanned monthly. Blood flow was reflected by the following parameters: resistance index (RI), time-averaged maximum velocity (TAMV), diameter of the vessel (D) and the volume of blood flow (VOL). RI values were negatively correlated to all other blood flow parameters (P < 0.01). Positive correlations occurred between TAMV, D and VOL (P < 0.0001). While blood flow parameters did not differ between cows (P > 0.05), the month of gestation showed a positive effect on RI and negative effects on TAMV, D and VOL (P < 0.0001). The RI was lower and TAMV, D and VOL higher in the uterine artery ipsilateral to the conceptus (P < 0.05). RI values decreased continuously during the first 8 months of gestation and remained from then until birth at a relatively constant level. While TAMV increased especially in two-thirds of pregnancy, a relatively uniform rise of D was noticed. VOL increased exponentially with stage of gestation. The results show that transrectal Doppler sonography is a suitable, noninvasive method for the examination of uterine blood flow during pregnancy in cows. Using this technique it might be possible in the future to determine the role of uterine blood flow in cows at the risk of abortion.     

Ultrasonographic evaluation of endometrial thickness near timed AI as a predictor of fertility in high-producing dairy cows

The objectives were to evaluate changes in endometrial thickness (ET) near the time of a synchronized ovulation and to assess the relationship of ET and fertility in lactating Holstein cows, with or without estrogen supplementation near timed ovulation. In Experiment 1, eight cows were examined with transrectal ultrasonography, once daily for 5 d, starting concurrent with PGF_2α (PGF) treatment during an Ovsynch protocol (GnRH - 7d - PGF - 72h - GnRH). The ET increased rapidly after PGF (from ∼7 to ∼9.5 mm), remained > 9 mm for the next 2 d, then decreased to ∼8 and 7.4 mm, 1 and 2 d, respectively, after the second GnRH. In Experiment 2,642 cows (total of 758 breedings) were subjected to an Ovsynch protocol (GnRH - 7d - PGF - 56h - GnRH - 16h - timed AI); cows received either no further treatment (Ovsynch) or 1 mg of estradiol-17β im 8 h before the second GnRH (Ovsynch + E2). For both uterine horns, ET was measured (∼2 cm from the internal uterine body bifurcation) before E2 treatment (48 h after PGF). In cows with ET ≤ 8 mm vs > 8 mm, rates of ovulation were 86.0% (n = 136) vs 98.1% (n = 472; P < 0.01), respectively, and percentage pregnant per AI (P/AI) were 26.7% (n = 146) vs 42.7% (n = 524; P < 0.01). Treatment with E2 increased P/AI in cows with lower ET (Ovsynch + E2 = 37.0% vs Ovsynch = 23.3%; P = 0.07), but did not significantly improve P/AI in cows with ET > 8 mm (Ovsynch + E2 = 43.4% vs Ovsynch = 42.1%). In conclusion, a single ultrasonographic evaluation of ET in Holstein cows 48 h after PGF treatment in an Ovsynch program was a good predictor of ovulation failure and pregnancy success. Perhaps poor fertility in cows with reduced ET was low peripheral E2 concentrations near AI, poor P4 priming, or luteolysis failure during timed AI procedures.     

Influence of intrauterine infections and follicular development on the response to GnRH administration in postpartum dairy cows

The effects of intrauterine infections and prior follicular development on the response to gonadotropin releasing hormone (GnRH) administration in postpartum dairy cows were studied. Fifty lactating Holstein cows were assigned at random to one of two groups after calving. Group I (control) consisted of 25 cows given a single intramuscular injection of saline on Day 15 postpartum. Group II (treated) consisted of 25 herdmates given a single i.m. injection of 100 mug of GnRH on Day 15 postpartum. Palpation per rectum and real-time ultrasonography were used to monitor ovarian activity, and endometrial swabs were cultured to determine the presence of uterine infection. Blood samples were collected for progesterone (P(4)) and luteinizing hormone (LH) analysis. Fourteen cows (control, n = 5; treated, n = 9) did not ovulate during the first 60 d postpartum. Ovaries in these cows contained 4 to 8-mm size follicles and both P(4) and LH remained at basal concentrations. Fourteen other cows (control, n = 6; treated, n = 8) ovulated by Day 15 postpartum. Follicles >/= 10 mm were demonstrable in the ovaries of these cows before or by Day 12 postpartum. GnRH treatment had no effect on the lifespan of the existing corpus luteum in these cows. In the remaining cows, 7 of 14 Control and all 8 Treated cows ovulated within 3 d of treatment. All cows ovulating within this period were free of uterine infection and the ovaries contained follicles 相似文献   

Low semen dose intracornual insemination of cows at fixed time after PGF2alpha treatment or at spontaneous estrus

The numbers of spermatozoa per insemination and the site of semen deposition in the uterine horn appear to interact to influence pregnancy rate. In two experiments, the effect of a single low dose (2 x 10(6) spermatozoa) intracornual insemination (LD-ICI) on bovine pregnancy rate was compared with that of intracornual (SD-ICI) and conventional (SD-AI) inseminations of 40 x 10(6) spermatozoa. In Experiment 1, 157 cows were treated twice with PGF(2)alpha at a 14-day interval and inseminated at a fixed time (80-82 h) after the second PGF(2)alpha injection using LD-ICI (n=44), SD-ICI (n=61) or SD-AI (n=52). In LD-ICI and SD-ICI groups, semen was deposited in the horn ipsilateral to the ovulatory follicle close to the utero-tubal junction (LD-ICI-UTJ, n=33 and SD-ICI-UTJ, n=41) or in the middle part of the horn (LD-ICI-MH, n=11 and SD-ICI-MH, n=20). Pregnancy rates after LD-ICI-UTJ, LD-ICI-MH, SD-ICI-UTJ and SD-ICI-MH were 27%, 27%, 39% and 35%, respectively (P>0.05). The total pregnancy rate after LD-ICI (27%) did not differ (P>0.05) from that after SD-ICI (37%) or SD-AI (34%). In Experiment 2 (field trial), 362 cows were allotted, at spontaneous estrus, to LD-ICI-UTJ (n=86), LD-ICI-MH (n=97) or SD-AI (n=179). Pregnancy rates after LD-ICI and SD-AI were 47% and 45%, respectively (P>0.05). After LD-ICI-UTJ, the pregnancy rate (54%) did not differ significantly (P>0.05) to that obtained after LD-ICI-MH (41%) and after SD-AI (45%). The results of the study show that the single intracornual insemination of cows with 2 x 10(6) spermatozoa at fixed time, 80-82 h after the second PGF(2)alpha injection or at spontaneous estrus resulted in similar pregnancy percentage as intracornual and conventional inseminations with 40 x 10(6) spermatozoa per semen dose. With intracornual insemination using low or standard dose of spermatozoa, the pregnancy rates were not significantly affected by the exact site of semen deposition in the uterine horn, near the utero-tubal junction or in the middle part.     

Hemodynamic changes evaluated by Doppler ultrasonographic technology in the ovaries and uterus of dairy cattle after the puerperium

The present detailed study aimed to establish for the first time the ovarian and uterine hemodynamic change in dairy cows after the end of the puerperal period to investigate a possible association between Doppler indices and volume of blood flow. Twenty cows weighing 500–600 kg (mean 400 ± 50 kg) and 4–5 years of age (mean 3.2 ± 0.5 years) categorized into two main groups (true anestrum, with corpus luteum, n = 10) and (normal cyclic, n = 10), The period of examination started from day 39 till day 70 after calving with day after day routinely examination by b-mode and Doppler performed on both ovaries with ovarian arteries (OA) and uterus with uterine arteries (MUA) in the ipsilateral (ipsi) and contralateral (contra) side to ovulation, in addition to a thickness in horns and body was measured. Estradiol and progesterone were also measured. Results showed that both Doppler indices in the OA and MUA ipsi and contra had a positive (P ≤ 0.001) correlation with contra Doppler indices, but revealed a negative (P ≤ 0.05) correlation with ipsi and contra Doppler velocities, blood flow rate and volume in anestrum cows. Both ovarian and uterine ipsi indices showed an increase (P ≤ 0.05) in the anestrum cows, and both PSV and EDV of both arteries ipsilateral showed (P ≤ 0.05) a decrease in the anestrum cows, the ipsi and contra ovarian and uterine colored % were lower in anestrum group than the normal group. Estradiol (P ≤ 0.05) decreased in anestrum cows than the normal, while progesterone increased in the anestrum group. Conclusion, although uterine and ovarian morphology were changed in anestrum cows, the vascular system of the ovary as well as uterus underwent much more marked vascular changes, the most significant being that of blood flow velocities and volume.     

Side of gestation in dairy heifers affects subsequent sperm transport and pregnancy rates after deep insemination into one uterine horn

Effects of side of previous gestation on sperm transport and pregnancy rates after deep cornual insemination were evaluated in 1686 Friesian cows in their first lactational period. Only single ovulating animals were used. At insemination, semen was deposited deep into the uterine horn ipsilateral or contralateral to the preovulatory follicle. A total of 876 cows (52%) ovulated in the ovary ipsilateral to the postgravid horn, and 810 cows ovulated in the contralateral ovary. Semen was deposited into the previously nongravid uterine horn of 832 cows, and into the gravid horn of 854 cows. The pregnancy rate was higher (P < 0.00001) for semen deposition into the previously nongravid horn (46.6%) than for semen deposition into the gravid horn (35.7%). For inseminations ipsilateral to the side of impending ovulation, pregnancy rates were higher (P = 0.0004) when ovulations occurred on the opposite side to the postgravid horn than on the same side. Pregnancy rates were higher (P = 0.002) for contralateral inseminations when ovulations occurred on the same side to the postgravid horn than on the opposite side; they were higher (P = 0.0001) for total ipsilateral than for total contralateral inseminations. There was no difference between ipsilateral and contralateral inseminations (P = 0.64) when ovulation occurred ipsilateral to the postgravid horn, but pregnancy rates were higher (P < 0.00001) when ipsilateral insemination was carried out into the nonpostgravid horn. Results indicate that the side of gestation in dairy heifers affects subsequent pregnancy rates after deep insemination into one uterine horn, possibly by affecting sperm transport.     

Relationships between maternal hormone secretion and embryo development on day 5 of pregnancy in dairy cows

In cattle, increasing early embryonic losses are associated with inadequate progesterone concentrations within the first three weeks of pregnancy. The aim of this study was to investigate the complex relationship between early maternal progesterone concentration and embryo development early within the first week of pregnancy, specifically, on day 5 post-oestrus in dairy cows. Twenty Holstein-Friesian cows at the end of lactation were inseminated at oestrus (day 0) and on day 5 post-oestrus cows were slaughtered and the reproductive tract flushed to determine the presence and stage of embryo development. Three cows that had failed to synchronise correctly were excluded from analysis while in the remaining 17 cows 11 (65%) were pregnant with embryos at the morula (n = 3), 9-16 (n = 3) and 8-cell (n = 5) stages of development. No differences in day 5 plasma progesterone concentrations or corpus luteum (CL) size or progesterone content were observed between pregnant (n = 11) and non-pregnant (n = 6) cows. In cows with embryos beyond the 8-cell stage of development (n = 6) plasma progesterone concentration (P < 0.001) and CL weight (P < 0.01) were higher and plasma insulin concentrations lower (P < 0.001) than in cows with 8-cell embryos (n = 5). In addition there was a negative relationship between plasma progesterone and plasma insulin in pregnant cows (R(2) = 0.65; P < 0.005). In cows with an embryo present in the oviduct, oviductal glucose concentrations were lower (P < 0.05) than in cows with no embryo present. These results confirm progesterone is not only directly associated with embryo development, but that it may indirectly modulate embryo development via changes in the oviductal environment. In summary, the association between maternal progesterone concentration and embryo development exists as early as day 5 of pregnancy in dairy cows.     

Effect of postpartum suppression of ovulation on uterine involution in dairy cows

The objective of this study was to investigate the effect of time of first postpartum ovulation after calving on uterine involution in dairy cows with and without uterine puerperal disease. Transvaginal follicular puncture (FP) of follicles >6 mm suppressed ovulation and development of a CL until Day 42 after calving. Fifty-three lactating Holstein Friesian cows (3.4 ± 1.2 years old, parity 2.5 ± 1.0 [median ± mean absolute deviation]) were divided into groups on the basis of the presence (UD+) or absence (UD−) of uterine disease and whether FP was carried out (FP+) or not (FP−). Uterine disease was defined as the occurrence of retained fetal membranes and/or metritis. This resulted in the following groups: UD−FP− (n = 15), UD−FP+ (n = 13), UD+FP− (n = 13), and UD+FP+ (n = 12). A general examination, vaginoscopy, transrectal palpation, and transrectal B-mode sonography of the reproductive organs were conducted on Days 8, 11, 18, and 25 and then every 10 days until Day 65 after calving. After hormonal synchronization of ovulation (cloprostenol between Days 55 and 60 postpartum and GnRH 2 days later), cows were inseminated in the next spontaneous estrus. On average, the cows ovulated on Day 21.0 ± 6.0 (UD−FP−), 50.0 ± 4.0 (UD−FP+), 16.0 ± 3.0 (UD+FP−), and 48.0 ± 2.0 (UD+FP+) postpartum. Calving-to-conception interval and first-service conception rates were not affected by FP (P > 0.05). Healthy cows with FP had smaller (P < 0.05) uterine horn and cervical diameters assessed sonographically than cows without FP. FP reduced the prevalence of purulent vaginal discharge and uterine size assessed transrectally in UD+ cows (P < 0.05). The results showed that suppression of an early ovulation by transvaginal FP improved uterine involution in cows with and without uterine disease.