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This study aimed to evaluate the role of prostaglandin F2a (PGF) on ovulation. In Experiment 1, cows were randomly allocated to two treatments to receive 150 ug of d-Cloprostenol (PGF Group, n = 12) or 2 mL of NaCl 0.9% (Control Group, n = 11) and CIDRs, were removed 4 days later. No cow ovulated in Control and PGF groups. In Experiment 2, cows were randomly separated into two experimental groups to receive 4 injections of 150 ug of d-Cloprostenol (n = 9) or 2 mL of NaCL 0.9% (n = 9). In this experiment, ovulation was not observed in any cows. In Experiment 3, ovariectomized cows receive three injections of 300ug of PGF analog (PGF Group, n = 5), 100ug of Lecirelin (GnRH Group, n = 5) or 2 mL of PBS (Control Group, n = 4). The LH concentration was higher (P 11.5 mm) were treated with Saline (Control Group, n = 6); Lecirelin (GnRH Group, n = 7) or Cloprostenol Sodium (PGF Group, n = 6). There was a significant increase in the vascular area of follicles from 0 to 24 h in GnRH and PGF treatments. In conclusion, PGF was not able to induce ovulation in cows with high or low plasma progesterone concentration. Additionally, PGF alone was not able to induce LH release and follicle luteinization, but increased follicular vascularization. O objetivo deste estudo foi avaliar o papel da prostaglandina F2a (PGF) na ovulação. No Experimento 1, as vacas foram alocadas aleatoriamente em dois tratamentos para receber 150 ug de d-Cloprostenol (Grupo PGF, n = 12) ou 2 mL de NaCl 0,9% (Grupo Controle, n = 11) e os CIDR, foram removidos 4 dias depois. Nenhuma vaca ovulou nos grupos Controle e PGF. No Experimento 2, as vacas foram separadas aleatoriamente em dois grupos experimentais para receber 4 injeções de 150 ug de d-Cloprostenol (n = 9) ou 2 mL de NaCL 0,9% (n = 9). Não foi observada ovulação em nenhum dos animais deste experimento. No Experimento 3, vacas ovariectomizadas receberam três injeções de 300ug de análogo de PGF (Grupo PGF, n = 5), 100ug de Lecirelina (Grupo GnRH, n = 5) ou 2 mL de PBS (Grupo Controle, n = 4). A concentração de LH foi maior (P 11,5 mm) foram tratadas com solução salina (Grupo Controle, n = 6), Lecirelina (Grupo GnRH, n = 7) ou Cloprostenol Sódico (Grupo PGF, n = 6). Houve um aumento significativo na área vascular dos folículos de 0 a 24h nos tratamentos com GnRH e PGF. Em conclusão, a PGF não foi capaz de induzir ovulação em vacas com alta ou baixa concentração plasmática de progesterona. Além disso, a PGF sozinha não foi capaz de induzir a liberação de LH e a luteinização do folículo, mas aumentou a vascularização folicular . Made available in DSpace on 2021-05-14T02:20:32Z (GMT). No. of bitstreams: 1 cpafro-18563.pdf: 1421435 bytes, checksum: dade7a90b48343362cf148d99ae6e08a (MD5) Previous issue date: 2021

An 18-y-old female llama ( Lama glama) in Saskatoon, Saskatchewan was examined during a routine herd check, and a mass was detected in the ventral cervical area just below the angle of the jaw. No clinical signs were evident except for the mass and chronic loss of body condition. Postmortem examination revealed bilateral enlargement of the thyroid gland with multiple cysts. Histopathology of the thyroid gland revealed follicular compact-cellular carcinoma lesions, with infiltration of neoplastic thyroid follicular cells in regional lymph nodes.

Gonadal steroids hormones indirectly regulate gonadotropin-rleasing hormone (GnRH) secretion. Kisspeptin (Kp) co-expresses steroid receptors and modulates GnRH release. The objective of the study was to characterise the number and proportion of GnRH and Kp immunoreactive cells and their association in the preoptic area (POA) and hypothalamus during different phases of the oestrous cycle in cows. Daily ovarian ultrasonography was performed to detect follicle development and ovulation (Day 0) after prostaglandin treatment. On Day 5, cows were assigned randomly to the following groups: proestrus (n = 2), metestrus (n = 2) or diestrus (n = 3). Cows in the diestrus group were killed on Day 8. Cows in the proestrus and metestrus groups were given luteolytic dose of prostaglandin on Day 5.5 and Day 6 and were killed on Day 7 and 24 h after the ensuing ovulation, respectively. Cow heads were perfused with 4% paraformaldehyde via the carotid arteries to fix the brain in situ. The brain-stem (rostral portion of the POA to the mamillary body) was isolated by dissection and placed in 4% paraformaldehyde for 48 h. Following cryoprotection, the tissue block containing the POA and hypothalamus was frozen at –80°C and sectioned serially at a thickness of 50 mm using a cryostat microtome. Every 20th free-floating section was processed for double labelling using 2 sequential immuno-peroxidase reactions and ABC staining; Kp was immuno-labelled with Nickel-DAB at a dilution of 1:10,000 rabbit anti-kisspeptin (AC566, INRA, France), and GnRH was stained with DAB using 1:40,000 rabbit anti-GnRH (LR-5, Dr Benoit). The numbers of neuron cell bodies and fibres were recorded in different areas of the POA and the hypothalamus by brightfield microscopy using 10× and 40× objective lenses. Data were compared among groups by ANOVA. Major aggregations of Kp cells were localised in the mPOA, OVLT, and ARC. Overall, the number of Kp cells was higher in the metestrus v. diestrus group (719 ± 94 v. 378 ± 8; P = 0.01), but was similar to the proestrus group (558 ± 9). The number of Kp cells in the POA (mPOA, OVLT) tended to be higher in the metestrus v. diestrus group (395 ± 56 v. 147 ± 44; P = 0.06), and was intermediate in the proestrus group (206 ± 6). The number of Kp cells in the ARC did not differ among groups (metestrus 310 ± 26, diestrus 206 ± 53, proestrus 321 ± 99; P = 0.4). The number of GnRH cells bodies was not different among groups (metestrus 40 ± 3, diestrus 50 ± 9, proestrus 43 ± 8; combined; P = 0.8), and the distribution was higher in the POA (metestrus 25 ± 2, diestrus 30 ± 3, proestrus 33 ± 2) than hypothalamus. The proportion of GnRH cells in apposition to Kp fibres tended to be highest in the proestrus v. metestrus and diestrus groups (50.5 ± 1% v. 34.1 ± 9% and 31.4 ± 3%; P = 0.09). In conclusion, the number of Kp immunoreactive cells, but not GnRH cells, present in the POA and hypothalamus changed among different phases of the oestrous cycle due primarily to an increase in number of Kp cells in POA during metestrus. The proestrous phase was associated with an increase in apposition between Kp fibres and GnRH cells.

Treatment with gonadotropin-releasing hormone (GnRH) has been used to induce ovulation in prepubertal heifers. The objective of this study was to evaluate whether peripubertal heifers will continue to ovulate at regular intervals (i.e. attain puberty) after GnRH treatment. Prepubertal crossbred Hereford heifers, 11.0 ± 0.5 months of age, 344 ± 26 kg of body weight, and at random stages of ovarian follicular wave status, were assigned to 2 groups (age- and weight-matched) and given GnRH (n = 24) or no treatment (Control, n = 22) on Day 0. Ovarian ultrasonography was performed every second day from Day 0 to 44 to record the size of 2 largest follicles and the corpus luteum (CL). Thereafter, examinations were done every 4 days until the third ovulation or Day 100, whichever came first. The first and second interovulatory intervals (IOI) were categorized as short (24 days), and the onset of the puberty was defined by the occurrence of 2 consecutive short or normal IOI (i.e. 3 uninterrupted ovulations). Proportional data were compared among groups by chi-squared test. Single-point measurements were compared by analysis of variance and multiple comparisons were made using Tukey’s test. Two heifers (one in each group) failed to ovulate during the experiment. The diameter of the largest follicle on Day 0 did not differ (P = 0.31) between the GnRH and Control groups (12.6 ± 0.37 mm and 13.1 ± 0.29 mm, respectively). The proportion of heifers that ovulated by Day 4 after treatment was higher in the GnRH than in the Control group (9/24 v. 1/22; P

The objective of this study was to evaluate the effect of a PGF2α-analogue (PGF) on ovulation and pregnancy rates after timed artificial insemination (TAI) in cattle. In experiment 1, crossbred dual-purpose heifers, in a crossover design (3 × 3), were given an intravaginal progesterone-releasing insert (controlled internal drug release [CIDR]) plus 1 mg estradiol benzoate (EB) intramuscularly (im) and 250 μg of a PGF-analogue im on Day 0. The CIDR inserts were removed 5 days after follicular wave emergence, and the heifers were randomly divided into three treatment groups to receive the following treatments: (1) 1 mg of EB im (EB group, n = 13); (2) 500 μg of PGF im (PG group, n = 13); or (3) saline (control group, n = 13), 24 hours after CIDR removal. Ovulation occurred earlier in EB (69.81 ± 3.23 hours) and PG groups (73.09 ± 3.23 hours) compared with control (83.07 ± 4.6 hours; P = 0.01) after CIDR removal. In experiment 2, pubertal beef heifers (n = 444), 12 to 14 months of age were used. On Day 0, the heifers were given a CIDR insert plus 2 mg EB im. On Day 9, the CIDR was removed and the heifers were given 500 μg of PGF im. Heifers were randomly assigned into one of three treatment groups: (1) 1 mg of EB (EB group; n = 145); (2) 500 μg of PGF (PG group; n = 149), both 24 hours after CIDR removal; or (3) 600 μg of estradiol cypionate (ECP group; n = 150) at CIDR removal. Timed artificial insemination occurred 48 hours after CIDR removal in the ECP group and 54 hours in the PG and EB groups. The percentage of heifers ovulating was higher in the PG group compared with the other groups (P = 0.08). However, the pregnancy rates did not differ among groups (47.6%, 45%, and 46.6%, for EB, PG, and ECP, respectively; P = 0.9). In experiment 3, 224 lactating beef cows, 40 to 50 days postpartum with 2.5 to 3.5 of body condition score were treated similarly as described in experiment 2, except for the ECP group, which was excluded. The treatments were as follows: 1 mg EB (EB group; n = 117) or 500 μg PGF (PG group; n = 107), 24 hours after CIDR removal. The calves were temporarily separated from their dams from Days 9 to 11. No difference was detected on the pregnancy rate between the EB and PG groups (58.1% vs. 47.6%, respectively; P = 0.11). Taken together, the combined results suggested that PGF2α could be successfully used to induce and synchronize ovulation in cattle undergoing TAI, with similar pregnancy rates when compared with other ovulatory stimuli (ECP and EB).

The objective was to determine the effects of exogenous prostaglandin F2α (PGF), with or without progesterone treatment, on first ovulation in prepubertal heifers. We tested the hypothesis that PGF has a luteolysis-independent ovulatory effect in cattle. Crossbred Angus heifers (12 to 14 mo old, 250 kg body weight, and an average body condition score of 3 out of 5) were examined by transrectal ultrasonography on two occasions, 11 days apart. Heifers in which a CL was not detected at either examination were considered prepubertal. Heifers were assigned randomly to three experimental groups: (1) PG group (N = 14); heifers were treated with a PGF analog (500 μg cloprostenol im) 5 days after the emergence of a spontaneous (i.e., naturally occurring, noninduced) follicular wave; (2) PPG group (N = 12); heifers were given an intravaginal progesterone-releasing insert (CIDR; Pfizer Animal Health, Montreal, QC, Canada), and a follicular wave was induced with 50 mg of progesterone + 2 mg of estradiol benzoate im, and a PGF analog was given at the time of CIDR removal, on Day 5 of the follicular wave (on average, 8.6 ± 0.5 days after CIDR insertion); and (3) control group heifers were given no treatment (N = 14). Heifers were examined daily by transrectal ultrasonography from the start of the experiment to confirmation that ovulation had occurred, or to 5 days after PGF injection (PG and PPG groups) or until dominant follicles of the next follicular wave reached 8 mm (control group). The percentage of heifers that ovulated within 10 days after wave emergence was higher in PPG (10/12; 83.3%) and PG (11/14; 78.5%) groups than in control (1/14; 7.1%; P < 0.0001). Ovulations occurred 69.6 ± 6 h and 93.8 ± 5 h after PGF treatment in PPG and in PG groups, respectively, whereas only one heifer in the control group ovulated 96 h after Day 5 of follicular wave (P = 0.13). In summary, PGF treatment was associated with ovulation in prepubertal heifers whether or not exogenous progesterone was used as a pretreatment. The hypothesis that PGF will induce ovulation by a luteolysis-independent mechanism was supported.

Reproductive data from 304 cows were analyzed in milk herds of the western central region of the Rio Grande do Sul (RS), Brazil, to evaluate the effect of diseases in the postpartum period and their effect on the reproductive issues related to specialist (n = 180), semi-specialist (n = 84), and non-specialist (n = 40) systems of milk production. For statistical analysis ANOVA and correlation at 5% significance were used. The results revealed that 42% of females had postpartum disorders (129/304) and 58% were healthy (175/304). At 60 days after AI, 51% (114/225) of the cows were pregnant. Sick postpartum animals had a low rate of pregnancy (19%). In the specialized and non-specialized systems, a correlation (P = 0.00227; 0.0310) was detected between healthy animals and pregnant, among patients and non-pregnant (P = 0.0289; 0.0160), respectively. The incidence of uterine infection detected by ultrasound after parturition (28%) was higher than the incidence in animals with mastitis (16%). None of the production systems has proved to be an effective model to prevent postpartum disease. The incidence of disease postpartum, as well as the incidence of uterine infections, was similar between the systems of production. The neosporose, uterine infections and mastitis were the reproductive health problems most prevalent in the study. This study was support by CNPq graduate funding to the first and second authors.

The aim of this research was to determine the influence of Neospora caninum (NC) infection on reproductive parameters of Holstein dairy cows. The study was performed at 32 farms in the south of Brazil, latitude 27°30′S to 31°S and longitude 51°30′W to 55°30 W Farms included in this study met rigorous vaccination schedule for infectious bovine rhinotracheitis, bovine viral diarrhea virus, leptospirosis, and brucellosis. Blood samples collected from the dairy cows were submitted to serologic testing by an indirect fluorescent antibody test (IFAT) and were distributed into 2 groups: seropositive (GP; n = 160) and seronegative (GN; n = 558). The dogs (n = 51) of the farms were tested by IFAT. After abortion, fetuses were frozen at -80°C and submitted to PCR detection of NC in tissues. Seropositive cows that aborted were also tested by IFAT. Pregnancies of GP and GN cows were mon- itored by periodic ultrasound exams. After parturition or abortion all cows in GP and GN groups were submitted to gynecological exams. Cows that developed disease (clinical mastitis, metabolic disease, or laminitis) after parturition or abortion were excluded from the analysis to prevent any distortion of data. Farms were divided into 3 categories according to production technology, specifically, average milk production per cow per lactation: high (>25 kg), medium (15-25 kg), and low (< 15 kg). Data was analyzed by ANOVA using SAS® software (SAS Institute, Cary, NC, USA) at a level of 5% significance and Student’s t-test for average reproductive parameters. The alternative hypothesis of the study was that at least 1 reproductive parameter was influenced in GP after abortion compared with GN cows that aborted. The null hypothesis was that there was no influence of NC antibody titer on reproductive parameters. The prevalence of antibody for NC in dairy cows was 24.48%. There was no prevalence difference among production systems (P > 0.05). The prevalence in dogs was 48.6% and did not differ among production systems. Fifty-nine (41.37%) NC-seropositive cows aborted. This differs significantly from the seronegative cow abortion rate (n = 17; 2.6%; P < 0.001). Occurrence of retained fetal membranes (RFM), endometritis, absence of uterine infection after abortion, and days between abortion and first estrus can be observed in Table 1. Abortion occurred between the fifth and eighth month of pregnancy. Occurrence of RFM was more frequent in cows that were seropositive. The period between abortion and first estrus was 79.06 v. 65.8 days for seropositive and seronegative groups, respectively, which differed significantly (P < 0.001). The results suggest that the higher occurrence of RFM after abortion in dairy NC-seropositive cows affects uterine involution, resulting in a delay of ovarian activity. Table 1.Neospora caninum seropositive and seronegative cows that aborted and their reproductive parameters. This study was supported by CNPq graduate funding.