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Protocols to artificially induce cows and heifers into lactation are effective and commercially available in Brazil. However, these protocols demand long hormonal treatments, which is debatable since little research has been done in the subject. To further understand artificial induction to lactation (AIL) protocols, we conducted two experiments. In experiment 1, our objective was to better characterize steroidal profile during an AIL protocol and assess the estradiol (E2) and progesterone (P4) serum profiles of Jersey cows (n=6) subjected to a conventional protocol. In experiment 2, we aimed to compare milk production and serum E2 concentrations of Holstein heifers induced into lactation by the standard AIL protocol (15 injections of E2 and 8 P4 injections) and by a short protocol in which the number of E2 injections and, consequently, the overall dosage of E2, were reduced (8 injections of E2 and 8 P4 injections). We hypothesized that a short AIL protocol (8 days) would be as efficient as the long standard protocol of 15 days. Our hypothesis was confirmed, since we demonstrated that a shorter protocol was able to induce lactation in Holstein heifers without hindering milk production. [ABSTRACT FROM AUTHOR]

Although several studies have shown the inhibitory effects of Tropaeolum majus extracts (HETM) on angiotensin-converting enzyme (ACE) activity, no studies have been carried out during the beginning of pregnancy, when humoral and hormonal imbalance may affect zygote and early embryo transport. This study investigates whether HETM can affect embryonic development when administered during the one-cell-blastocyst period. Pregnant Wistar rats received orally the HETM (3, 30, and 300 mg/kg/day) from the est to the 7th gestational day. Rats were killed on the 8th day of pregnancy and the following parameters were evaluated: clinical symptoms of toxicity (including organ weights), number of corpora lutea, implants per group, preimplantation losses ratio, and the serum levels of dehydroepiandrosterone (DHEA), estradiol, and progesterone. No clinical symptoms of maternal toxicity were evidenced. On the 8th day of pregnancy, the levels of DHEA and estradiol were increased and significant preimplantation losses were observed at all doses used. The present study reveals that the HETM can raise levels of DHEA and estradiol and induce difficulty in the embryo implantation in the early stages of pregnancy. The data contributes significantly to the safety aspects of using this natural product when trying to get pregnant or during pregnancy. [ABSTRACT FROM AUTHOR]

Abstract: In Experiments 1, 2, and 3, we evaluated the effects of temporary weaning (TW), equine chorionic gonadotropin (eCG), and follicle-stimulating hormone (FSH) treatments on results of a fixed-time artificial insemination (TAI) protocol in postpartum Bos indicus cows. In Experiment 1, treatment with 400 IU eCG or with TW for 48h consistently improved pregnancy rates (PRs) at TAI, but, in Experiment 2, FSH treatment was less effective than eCG or TW. In Experiment 3, the inclusion of eCG treatment in cows subjected to TW did not improve PRs. We concluded that TW or 400 IU eCG should be included in the TAI protocol in postpartum Bos indicus cows to enhance fertility. In Experiment 4, we used records from heifers and cows treated with the proposed protocol during the 2006–2007 (n =27,195) and 2007–2008 (n =36,838) breeding seasons from multiple locations in Brazil to evaluate factors potentially affecting PRs. Overall PR at TAI was 49.6% (31,786 of 64,033). Pregnancy rate differed (P <0.01) among farm within location (results ranging between 26.8% and 68.0%; P <0.01), cow group within farm, by breed (Bos indicus, 48.3% [26,123 of 54,145]; Bos taurus, 61.7% [3652 of 5922]; and crossbred Bos indicus × Bos taurus, 50.7% [2011 of 3966]), category (nulliparous, 39.6% [2095 of 5290]; suckled primiparous, 45.2% [3924 of 8677]; suckled multiparous, 51.8% [24,245 of 46,767]; and nonsuckled multiparous, 46.1% [1522 of 3299]), body condition score at TAI (≤2.5, 43.0% [3409 of 7923]; 3.0, 49.6% [18,958 of 38,229]; and ≥3.5, 52.7% [9419 of 17,881]). Days postpartum at beginning of protocol did not affect PR (30 to 60 d, 47.6% [4228 of 8881]; 61 to 90 d, 51.7% [16,325 to 31,572]; and 91 to 150 d, 50.8% [7616 to 14,991]; P >0.1). Pregnancy rate was also consistently affected (P <0.01) by sire (results ranging from 7.2% to 77.3%) and artificial insemination technician (results ranging from 15.1% to 81.8%). [Copyright &y& Elsevier]

This trial was to evaluate the effect of progesterone (P4) and/or 17β-estradiol (E2) on incidence of short cycles (SC) after induction of ovulation with calf removal (CR) and GnRH injection in anestrous Nelore cows. Cows (n=142; 43±12 DPP) were evaluated by 2 ultrasound (US) exams 8 d apart (day -16 and day -8) for cyclicity. Anestrous cows (n=114) were randomly assigned to receive a 6 d treatment with an intravaginal P4 device (CIDR® Pfizer Animal Health, Brazil) prior CR and/or 1 mg i.m. injection of 17β-estradiol 48h after beginning of CR (4 treatments; 2x2 factorial design). On day -2 all cows suffered CR for 54h and received a GnRH injection at the end of CR (day 0). Only cows that ovulated within 48 h after GnRH injection (evaluated by US on days 0 and 2) were used (Control, n=23; E2, n=25; P4, n=19; P4+E2, n=18). Blood samples were collected on days 0, 5, 7, 9, 12, 15 and 19 for corpus luteum lifespan evaluation, by serum P4 analysis. Cows were considered having SC if P4 decreased more than 50% between days 5 and 7. Percentage of cows exhibiting SC was analyzed by logistic regression and P4 were analyzed by PROC MIXED of SAS. P4 were higher on day 5 than on day 0 (P<.01) on all treatments. Serum P4 increased (P<.05) between days 5 and 7 on P4 (from 2.3±0.5 to 3.7±0.5 ng/mL) and P4+E2 (from 2.4±0.5 to 3.3±0.5 ng/mL) groups and decreased (P<.01) on Control (from 2.9±0.4 to 1.9±0.4 ng/mL) and E2 (from 1.9±0.4 to 0.8±0.4 ng/mL) groups. Cows treated with P4 (P4 and P4+E2) had higher serum P4 than cows not treated (Control and E2) on days 7, 9, 12 and 15 (P<.01). Incidence of SC was lower in cows treated with P4 than in cows not treated (23.5 vs. 79.2%; P<.01), while treatment only with 17β-estradiol did not differ (P>.10) from control group (76 vs 82.6%). Cows not treated with P4 that showed heat had the same incidence of SC than cows not detected in estrus (75 vs. 80%; P>.1). In conclusion, 6 d treatment with P4 prior ovulation on anestrous cows warranted a normal luteal lifespan, while administration of 1mg of 17β-estradiol did not prevent occurrence of SC. [ABSTRACT FROM AUTHOR]