Mg Of Norgestomet Research Articles

Fertility in Cebú × brown Swiss cows treated with prostaglandins, progesterone and eCG

Objective: To evaluate the application of one or two doses of prostaglandin F2?(PGF2?), the application of a progestogen on different days of the estrous cycle and theusage of eCG in the estrus synchronization and fertility of Zebu × Brown Swiss cows.Design / methodology / approach: The study was based on three protocols. The firstconsisted of two treatments: PGI) 26 cows were injected with a single 25 mg dose ofPGF2? and 10 cows with two 25 mg doses of PGF2? at a 14-day interval. Protocol 2consisted of two treatments: NG14) 11 cows were implanted with 3 mg of Norgestometon day 7 of their estrous cycle and NG7) 11 animals received the same dose on day 14.In protocol 3 all cows were implanted with 3 mg of Norgestomet for 9 days, 48 h beforeremoving the implant, 25 mg of PGF2? was applied. Once the implants were removed,they were distributed into two treatments. Norgestomet (n = 11) without eCG andNorgestomet + eCG (500 IU) (n = 11). Results: The application of PGF2? at two times had no influence (p > 0.05) in theestrous percentages and conception. The NG7 achieved estrous synchronization in 81.8% of the cows, in between 24 and 36 h, compared to 45.4 % of the NG14; however, theconception rate was lower (p ? 0.05). The eCG application synchronized 90.9 % ofestrous between 24 and 36 h, compared with 36.4 % of the group with no eCGapplication.Study limitations / implications: Transrectal ultrasounds are required to assess theovarian structures present at the time of the estrus onset in a synchronization protocol.Findings / conclusions: Cows that present corpus luteum do not require more thanone injection of PGF2?, the pregnancy percentage increases when Norgestomet isimplanted on day 14 of the estrous cycle, in addition the application of eCG increasesthe synchronization percentage of the heat between 24 to 36 h after the progestogenwithdrawal.

Effectiveness of a low-dose Norgestomet ear implant in short-term protocols to induce estrus in ewes during the non-breeding season in Brazil.

ABSTRACT The objective of this study was to evaluate the reproductive performance of ewes subjected to a short-term protocol for estrus induction using 1 mg of Norgestomet during the non-breeding season in Brazil. A total of 84 ewes were randomly divided into two equal groups (n = 42 per group). Controlled Internal Drug Release (CIDR) containing 330 mg progesterone was inserted into the vagina in the first 42 ewes, and for the other 42 ewes in the second group, 1 [...]

110 First ovum pickup-in vitro-produced lidia breed calves using Lidia breed recipients: influence of age and state of the recipients and in vitro-produced embryos on pregnancy rates

We previously demonstrated the success of in vitro embryo production (IVP) in Lidia breed cattle (Gamarra Lazo et al. 2017 Reprod. Fertil. Dev. 30, 187). As in other species, the success of IVP is linked to the birth of calves from this technique. In the Lidia breed, an important factor to consider is the use of Lidia recipients in order to keep the temperament characteristic of this breed to next generations. The aim of the study was to produce ovum pickup (OPU)-IVP calves in the Lidia breed and to assess the effects of recipient and embryo related factors (status of the recipients; development stage of IVF embryos) on pregnancy rate following embryo transfer. Ovum pickup-IVP embryos from Lidia breeds were produced by a standard protocol (Gamarra Lazo et al. 2017 Reprod. Fertil. Dev. 30, 187). Numbers of blastocysts and expanded blastocysts were recorded on Day 7. A total of 27 blastocysts (B) and 34 expanded blastocysts (EB) of excellent quality (grade 1 according to IETS classification) were selected for fresh transfer. All embryos were transferred to Lidia breed recipients (heifers or cows) by a single operator under similar environmental and field conditions. Recipients were synchronized by subcutaneous insertion of an ear implant of 3.3mg of Norgestomet (Crestar®, MSD, Courbevoie, France) for 9 days. Two days before implant withdrawal, 0.5mg of Cloprostenol (Estrumate®, MSD) was injected. No oestrous detection was performed and synchronized females were selected as recipients when they presented a well developed corpus luteum at Day 9 after implant withdrawal (Day 6 to 7 after the expected oestrus). Blood samples were collected from recipients to determine pregnancy status using the bovine pregnancy associated glycoprotein (Idexx, Westbrook, ME, USA) 50-60 days after transfer. Pregnancy rates were analysed by chi-square analysis to compare results between heifers and cows and between B and EB embryo stages. The overall pregnancy rate after transfer of IVP fresh embryos from Lidia breed averaged 41.0% (n=25). A higher pregnancy rate was achieved in cows compared to heifers [51.2% (21/41) v. 20.0% (4/20) respectively, P<0.05]. There was no difference in pregnancy rate between grade 1B [37% (10/27)] and EB [44.1% (15/34)] embryos (P>0.05). Surprisingly, these results suggest that Lidia breed cows are the best recipients for OPU-IVP embryos. This may be related to the limited feasibility of manipulating the uterine horn during the embryo transfer in Lidia breed heifers, which have a low weight (less than 280kg) and present a narrow rectum diameter. It has been also observed that the cervix is very thin and difficult to cross, thus increasing the stress and potentially inflammatory and immune products secretion. Development stage of embryos did not affect pregnancy rate. To our knowledge, no OPU-IVP Lidia breed calves have been reported previously following transfer into Lidia breed recipients. In the current work, 13 OPU-IVP Lidia breed calves were born. Therefore, we confirmed the possibility of applying OPU-IVP and embryo transfer techniques in this breed within a genetic program.

Evaluation of buffaloes' follicular dynamics and stress state under different ovulation synchronization protocols.

The aims of the present study were to analyze the effect of different hormonal protocols using an implant containing Norgestomet, at the ovulation synchronization in buffaloes and to verify the effect of the stress caused by manipulation of the herd during the experiment. Twenty-four female Murrah breed buffaloes, lactating, multiparous, aged from three to eight years, with a body condition score of 3.5 or higher (0 to 5) and with more than 45 days post partum, were used. These females were randomly distributed into one of the three groups (group 1, group 2 and group 3) with eight subjects in each. On day 0 (day 0), all animals received an ear progesterone implant with 3.0 mg of Norgestomet and an intramuscular (IM) injection with 2.0 mg of estradiol benzoate (EB). The implants were removed after nine days (day 9) and one single dose of PGF2α (0.15 mg d-cloprostenol, IM) was administered to all animals. On the same day, the group´1 and group 3 buffaloes were treated with 500 UI of eCG (IM). Two days later (day 11), 1000UI of hCG (IM) were administered to the group 1 and group 2 buffaloes. After the implant had been removed, an ultrasound evaluation was performed every 12 h, in order to access the ovarian follicular dynamics, using an Aloka 500 equipment with a 5 MHz transrectal probe. Blood samples were also taken on days 0, 9 and 11 to determine the plasmatic concentrations of cortisol and progesterone. No difference was observed in the ovulation rate (group 1: 62.5%, group 2: 50%, group 3: 75%). However, the size of the preovulatory follicles and the plasmatic concentration of cortisol had (P < 0.05). G3 was the most efficient group in promoting the ovulation synchronization, which suggests that this protocol can be used in Fixed Timed Artificial Insemination programs (FTAI) among postpartum, lactating Murrah breed buffaloes’.

Comportamiento sexual de novillas Brahman en el trópico bajo mediante control farmacológico del estro

Se utilizaron 33 novillas Brahman, con edades y pesos similares y se conformaron tres grupos para evaluar el comportamiento sexual mediante control farmacológico del estro. A cada grupo se le asignó al azar uno de los siguientes tratamientos: Grupo control, conformado por nueve novillas (G1); día cero: implante subcutáneo en la cara externa de la oreja con 3 mg de norgestomet, más inyección muscular de 3 mg de norgestomet y 5 mg de valerato de estradiol. Día siete: inyección muscular de 0,15 mg de (D+) cloprostenol. Día nueve: retiro del implante. Grupo dos (G2), igual que G1, pero en el día nueve se introdujeron 3 novillas en celo. Grupo tres (G3), igual que G1, pero el día nueve se introdujeron 3 novillas en anestro. Las novillas se observaron por 96 horas continuas. Los datos se recolectaron por el método de “Registro de secuencias”. La información se analizó mediante estadística descriptiva y se compararon los grupos para establecer diferencias. El 100% de las novillas expresaron signos de celo y su inicio no se vio alterado con la inclusión de novillas en celo o en anestro. Después de retirado el implante, el inicio de celos para G1 fue a las 29.5 ± 4.8 h; para G2 a las 26.1 ± 4.7 h y para G3 a las 26.36 ± 4.6 horas. La duración del celo para los grupos en el mismo orden fue de 13. 6 ± 9.1 h; 12.7 ± 6.5 h y 18.7 ± 4.7 horas. El mayor porcentaje de celos y número de conductas sexuales se alcanzó entre las 30-34 horas post-retiro de los implantes (G1: 100%; G2:88.8%; G3: 100%). La inclusión de novillas el día nueve del protocolo no alteró la iniciación o retardo de la presentación de celos.

Morphology and vascularization of the corpus luteum of peccaries (Pecari tajacu, Linnaeus, 1758) throughout the estrous cycle

The current paper characterizes the changes in morphology and vascularization of the corpus luteum of collared peccaries during the estrous cycle and correlates progesterone synthesis (P4). Twenty females were subjected to a treatment for estrus synchronization; an ear implant containing 1.5 mg of norgestomet was implanted on D0, whereas on D9 the peccaries received an IM injection of eCG 200UI and 50g of PGF2a. The animals were divided into four groups (G1, G2, G3 and G4) and euthanized on post-ovulation days 3, 12, 18 and 22. The ovaries were collected and the corpora lutea were measured and processed for histological and vascular density (Dv). Blood was collected for dosage of P4 serum. The morphology of the ovaries, the corpora lutea and P4 varied significantly during the estrous cycle (P&lt;0.001). There was a significant co-relationship between weight and length of the ovaries and CL (r = 0.66, r = 0.52, P&lt;0.05, respectively) and between weight, length and width of the CL and P4 (r = 0.51, r = 0.54 and r = 0.68, P&lt;0.05, respectively). The luteal Dv was highly influenced by the estrous cycle phase (P&lt;0.0001). The P4 and luteal Dv concentrations were higher in G2 and evidenced maximum secretory activity, with a highly significant correlation (P&lt;0.0001). Assessed lutein parameters may estimate the phase of the estrous cycle in peccaries and the functional activity of the corpus luteum.

Evaluation of estradiol benzoate as a pre-treatment for oocyte recovery in sheep

O objetivo deste estudo foi comparar o número de folículos, oócitos e a taxa de recuperação em ovelhas submetidas ao protocolo one-shot com ou sem priming ovariano de benzoato de estradiol (BE). Ovelhas não lactantes (n=33), multíparas, com idade média de cinco anos (intervalo 4-6) e um escore de condição corporal de 3,0±0,3 foram divididas em três grupos. O grupo one-shot (n=10) foi tratado com um implante subcutâneo contendo 1,5 mg de norgestomet do D0 ao D10, além de receberem 0,04 mg de D-loprostenol, 200 UI de hormônio folículo estimulante (FSH) e 300 UI de gonadotrofina coriônica equina (eCG) no D8. As ovelhas do grupo BE (n=11) receberam o mesmo tratamento do oneshot e uma aplicação de 0,6 mg de BE no D0. Os animais do grupo não tratado (n=12) não receberam hormônios. A aspiração folicular foi realizada por laparotomia 36 horas após a administração da gonadotrofina (D10) e os oócitos pesquisados e classificados com base na morfologia. Observou-se um aumento (p&lt;0,05) no número de folículos aspirados no grupo one-shot comparado com os grupos BE e não tratado (16,3±5,6 vs. 9,5±2,4 e 12,1±4,1) respectivamente. O número médio de oócitos e taxa de recuperação foram superiores (p&lt;0,05) nos grupos one-shot e BE em comparação com o grupo não tratado, o que resultou em 14,2±9,0 e 87,1% (142/163), 11,0±6,2 e 91,4% (122/134) vs. 6,8±3,5 e 71,9% (82/114), respectivamente. Concluiu-se que a BE não aumentou a eficiência do protocolo one-shot, mas foi significativamente superior os animais não tratados.

Prostaglandin treatment at the onset of norgestomet and estradiol-based synchronization protocols did not alter the ovarian follicular dynamics or pregnancy per timed artificial insemination in cyclic Bos indicus heifers

The aim of the present study was to evaluate the effects of the PGF2α treatment given at the onset of a synchronization of ovulation protocol using a norgestomet (NORG) ear implant on ovarian follicular dynamics (Experiment 1) and pregnancy per AI (P/AI; Experiment 2) in cyclic (CL present) Bos indicus heifers. In Experiment 1, a total of 46 heifers were presynchronized using two consecutive doses of PGF2α 12 days apart. At first day of the synchronization protocol the heifers received implants containing 3mg of NORG and 2mg of estradiol benzoate (EB). At the same time, heifers were randomly assigned to receive 150mg of d-cloprostenol (n=23; PGF2α) or no additional treatment (n=23; Control). When the ear implants were removed 8 days later, all heifers received a PGF2α treatment and 1mg of EB was given 24h later. The follicular diameter and interval to ovulation were determined by transrectal ultrasonography. No effects of PGF2α treatment on the diameter of the largest follicle present were observed at implant removal (PGF2α=9.8±0.4 vs. Control=10.0±0.3mm; P=0.73) or after 24h (PGF2α=11.1±0.4 vs. Control=11.0±0.4mm; P=0.83). No differences in the time of ovulation after ear implant removal (PGF2α=70.8±1.2 vs. Control=73.3±0.9h; P=0.10) or in the ovulation rate (PGF2α=87.0 vs. Control=82.6%; P=0.64) between treatments were observed. In Experiment 2, 280 cyclic heifers were synchronized using the same experimental design described above (PGF2α; n=143 and Control; n=137), at random day of the estrous cycle. All heifers received 300 IU of equine chorionic gonadotropin (eCG) and 0.5mg of estradiol cypionate (as ovulatory stimulus) when the NORG ear implants were removed. Timed artificial insemination (TAI) was performed 48h after implant removal and the pregnancy diagnosis was conducted 30 days later. No effects on the P/AI due to PGF2α treatment were observed (PGF2α=51.7 vs. Control=57.7%; P=0.29). In conclusion, PGF2α treatment at the onset of NORG-based protocols for the synchronization of ovulation did not alter the ovarian follicular responses or the P/AI in cyclic Bos indicus beef heifers synchronized for TAI.

Reproductive performance in out-of-breeding season of fatty ewes using implant norgestomet with or without PMSG

Pregnancy in out-of-breeding season in ewes increases the economical goals. Synchronization of estrus and ovulation is essential for above program. The aims of this study using implant norgestomet with or without Pregnant Mare Serum Gonadotropin (PMSG) were to evaluate the serum progesterone (P4) concentration changes: the conception rate and estimation of the lambing rate and litter size. In total, 80 non-cycling multiparous Iranian Kurdish breed fat-tailed ewes with <0/5 ng/ml P4 were used in April and May 2008 in the suburb of Mashhad, Iran. The animals were randomly divided into three groups: a control group (n = 30) without hormonal treatment, another group (n = 25) received 3 mg of norgestomet implant placed subcutaneously in the convex surface of the ear for 9 days, and the third group (n = 25) treated with 3 mg of norgestomet implant for 9 days with an IM injection of 500 IU PMSG at implant removal. The progesterone of treatment and control groups were measured on days 4, 9, and 13 after removal of the norgestomet using radioimmunoassay. Every five ewes were exposed to one ram after 24 h of norgestomet removal in treatment and control groups, simultaneously. The pregnancy was examined after 25 days of ram removal using ultrasonography. Progesterone concentration was significantly higher in treatment groups on 9 and 13 days after norgestomet removal (P < 0.05). The pregnancy rate in the control, non-PMSG, and PMSG treatments groups were 17%, 52%, and 72%, respectively. The rates of single and twin pregnancy in the non-PMSG treatment group were 69% and 31%, respectively. These rates in norgestomet and PMSG treatment group were 50% and 39%, respectively. Triplet pregnancy (11%) was observed only in the PMSG treatment group. It was concluded that using implant norgestomet especially accompanied with PMSG can increase and improve the fertilization rate of ewe in the out-of-breeding season program.

Effect of Artificial Cooling and its Combination with Timed Artificial Insemination on Fertility of Holstein Heifers During Summer

Correa-Calderón, A., Leyva, C., Avendaño, L., Rivera, F., Diaz, R., Alvarez, F.D., Ardon, F. and Rodriguez, F. 2009. Effect of artificial cooling and its combination with timed artificial insemination on fertility of Holstein heifers during summer. J. Appl. Anim. Res., 35: 109–112. In order to evaluate artificial cooling and timed artificial insemination (TAI) protocol on fertility during summer months, 90 Holstein heifers were randomly and equally assigned to three treatments: a) control group (S) with visual heat detection and insemination a.m-p.m after heat detection; b) a group (TAI+C) using a norgestomet ear implant (3 mg) plus an injection of 3 mg of norgestomet and 5 mg of estradiol valerate. The implant was removed after 9 d and 500 IU i.m ofeCG were administered at the same time, plus a cooling period with spray and fans beginning at time of implantation until 21 d after AI; c) a third group (C) with heat detection and AI a.m-p.m, starting the artificial cooling when animals initiated in the treatment until 21 d after AI. Temperature-humidity index (THI) averaged 85 during the trial. T3 concentration increased in treatment groups. Conception rate among treatment groups was similar (P>.05). Artificial cooling increased heifers comfort and TAI plus cooling did not show any improvement on fertility.

Embryo production and quality of Holstein heifers and cows supplemented with β-carotene and tocopherol

The hypothesis was that the intramuscular injection (i.m.) of β-carotene associated to tocopherol improves cow ( n = 86) and heifer ( n = 91) embryo production and quality. Time of estrus was synchronized in animals with an ear implant with 3 mg of norgestomet associated with an i.m. injection of 6 mg of norgestomet and 10 mg of estradiol valerate (CRESTAR ®, Intervert International B.V., Boxmeer, Holland) and superovulated by 8 i.m. FSH/LHp injections (400 IU-heifers and 500 IU-cows) in decreasing concentrations at 12 h intervals. Animals were inseminated 12 and 24 h after observed onset of estrus and embryos recovered 7 days later. Animals were randomly allocated to one of three treatments: (1) vegetable oil vehicle (control), (2) 800 mg of β-carotene and 500 mg of tocopherol (T800) and (3) 1200 mg of β-carotene and 750 mg of tocopherol (T1200). Supplemental injections were given at the day norgestomet implants were inserted and at first superovulatory injection. An index (Embryo Quality Index or EQI) was proposed to more precisely evaluate embryo quality (excellent*1 + good*2 + regular*3 + poor*4 + degenerate*5 + unfertilized ova*5)/total. There was an interaction between physiological stage (heifer or cow) and treatment on EQI ( P = 0.01) and on the proportion of viable embryos ( P = 0.03), where both variables were improved in T1200 cows, but not in heifers. The average EQI for heifers and cows in control, T800 and T1200 were 2.6 ± 0.3 and 3.6 ± 0.3; 2.5 ± 0.3 and 3.6 ± 0.3; 2.9 ± 0.3 and 2.7 ± 0.3, respectively. The average total number of viable embryos was greater ( P = 0.01) in supplemented cows (3.5 ± 1.1; 5.4 ± 1.4 and 7.5 ± 1.2 in control, T800 and T1200, respectively), but less ( P = 0.01) in heifers (7.5 ± 1.2; 5.6 ± 1.2 and 4.0 ± 1.1 in control, T800 and T1200, respectively). Supplementation injections of β-carotene associated to tocopherol improved embryo quality in superovulated Holstein cows, in the present experimental conditions and may be advantageous in similar embryo production systems. However, at dosages applied in the present experiment, this treatment should not be recommended for nuliparous heifers.

Uso do protocolo Crestar® em tratamentos utilizando benzoato de estradiol, PGF2±, PMSG e GnRH para controle do ciclo estral e ovulação em vacas de corte

O objetivo foi avaliar a eficiência do controle da ovulação utilizando os hormônios PMSG, GnRH, Benzoato de Estradiol e PGF2a junto ao protocolo CrestarÒ, para IA em tempo fixo. Foram utilizadas 348 vacas, cruzadas Nelore (Bos taurus indicus) X Charolês (Bos taurus taurus), divididas em dois grupos: 179 vacas paridas com 90 a 120 dias pós-parto e 169 vacas solteiras. Estes animais foram submetidos a cinco tratamentos: todas as vacas receberam o protocolo Crestar® como agente sincronizador do crescimento folicular. (implante subcutâneo com 3mg de norgestomet e injeção 3mg de norgestomet + 5mg de valerato de estradiol - i.m.). Após a remoção do implante (10 dias), as vacas foram submetidas aos cinco tratamentos de controle da ovulação: T1 - (n=70): injeção de solução fisiológica 48h após a retirada do implante (D 12); T2 - (n=68): 0,75mg de benzoato de estradiol 24h após a retirada do implante (D 11); T3 - (n=70): aplicação de 150mg de PGF2a, no dia da retirada (D 10) e 0,75mg de benzoato de estradiol 24h após a retirada do implante (D 11); T4 - (n=70): 500 UI de PMSG na retirada do implante (D 10) e T5 - (n=70): 500mg de GnRH 48h após a retirada dos implante (D 12). Todos os animais foram inseminados 54-56h após a retirada do implante. As taxas de prenhez foram analisadas estatisticamente por regressão logística. Não houve diferença entre os tratamentos (p&gt;;0,05) onde: 35,7, 31,4, 22,0, 37,0 e 42,8% para T1, T2, T3, T4 e T5 respectivamente.

Avaliação da reutilização de implantes auriculares contendo norgestomet associados ao valerato ou ao benzoato de estradiol em vacas nelore inseminadas em tempo fixo

Em fêmeas bovinas a utilização da técnica de inseminação artificial em tempo fixo (IATF) é possibilitada pelo emprego de fármacos que tem como objetivos sincronizar a emergência das ondas foliculares, os estros e a ovulação. Em rebanhos comerciais, o custo de tais fármacos deve estabelecer uma vantajosa relação com os benefícios. O presente estudo, objetivou comparar as taxas de prenhez em vacas Nelore (Bos taurus indicus) inseminadas em tempo fixo, tratadas com implantes auriculares contendo 3mg de norgestomet (Crestar®), novos (IN) ou utilizados uma vez (IR; reutilizados), associados a administração de norgestomet (NG) e valerato de estradiol (VE) ou progesterona (P4) e benzoato de estradiol (BE). Vacas Nelore PO (n=241), amamentando, com o bezerro ao pé, receberam um dos quatro tratamentos: Crestar®novo durante 10 dias associado a administração de 3mg de NG e 5mg de VE (grupo IN/NG+VE; n=61); Crestar®novo inserido durante 8 dias associado a 50mg de P4 e 2mg de BE (grupo IN/P4+BE; n=61); Crestar®reutilizado inserido durante 10 dias associado a administração de 3mg de NG e 5mg de VE (grupo IR/NG+VE; n=58) ou Crestar®reutilizado inserido durante 8 dias associado a e 50mg de P4 e 2mg de BE (grupo IR/P4+BE; n=61). No dia da remoção dos implantes os animais receberam 7,5mg de Luprostiol e 24 horas após a remoção 1mg de BE. A IATF foi realizada 54 a 56 horas após a retirada dos implantes. Após a IATF, as vacas tiveram os estros observados durante um período de 49 dias e em estro foram reinseminadas 12 horas após a observação. O diagnóstico de gestação foi realizado por ultra-sonografia 35 dias após a IATF e após o final da estação de monta. Foram avaliadas as taxas de prenhez na IATF (TP IATF) e no final da estação de monta (TP EM). Não houve interação entre as características dos implantes (novos e reutilizados) e os tratamentos administrados no dia da inserção do implante (NG+VE e P4+BE). A utilização do CIDR®novo ou reutilizado não teve efeito nas TP IATF (48,3% vs 48,7%) e nas TP EM (85,2 vs 86,5%). Os tratamentos com NG+VE e P4+BE não tiveram efeito nas TP IATF (49,5 vs 47,5%) e TP EM (86,5 vs 85,2%). Houve efeito do número de parições (primíparas e multíparas) nas TP IATF (35% vs. 52,7%; P&lt;0,01) e nas TP EM (71,9% vs. 90,2%; P&lt;0,01). Conclui-se que implantes de norgestomet novos e reutilizados, quando associados ao NG+VE ou P4+BE promovem taxas de prenhez bastante satisfatórias em vacas Nelore e que melhores taxas são obtidas em fêmeas multíparas.

363 EFFECT OF OESTRADIOL VALERATE OR BENZOATE ON INDUCTION OF A NEW FOLLICULAR WAVE EMERGENCE IN BOS INDICUS COWS AND HEIFERS TREATED WITH NORGESTOMET AURICULAR IMPLANT

Estradiol given during progestin-treatment promotes emergence of a new follicular wave in cattle. The interval from estradiol treatment to follicular wave emergence is dependent on the estradiol preparation, the dose, and possibly the animal category (cows or heifers). Therefore, this experiment aimed to compare the effects of either estradiol benzoate (EB) or estradiol valerate (EV) on the synchrony of ovarian follicular wave emergence in Bos indicus (Nelore) heifers and cows treated with a Norgestomet implant (Crestar�; Intervet, Boxmeer, The Netherlands; factorial 3 � 2 design). Lactating cows (n = 30; 70-90 days postpartum) and cycling heifers (n = 29) were homogeneously assigned, according to the presence of corpora lutea, to six experimental groups (G2EB, G2.5EV, and G5EV for each animal category). At random stages of the estrous cycle (Day 0), the females received an auricular implant and were assigned to receive 2 mg of EB (Farmavet, S�o Paulo, Brazil; 10 cows and 10 heifers; G2EB), 2.5 mg of EV plus 1.5 mg of Norgestomet (10 cows and 10 heifers; G2.5EV; half of a recommended dose), or 5 mg of EV plus 3 mg of Norgestomet (10 cows and 10 heifers; G5EV, full recommended dose) i.m. Transrectal ultrasonography was performed once daily from Day 0 to confirm the follicular dominance (new growing dominant follicle &gt;8 mm in diameter). The day of wave emergence was retrospectively defined as the day when the dominant follicle was first detected at a diameter of 3 mm. Two-way analysis of variance was used to compare the effects of treatments (G2EB, G2.5EV, and G5EV), category (cows and heifers), and the treatments-by-category interaction on the interval from beginning of the treatment to wave emergence. The LSD was used to locate differences among groups and the Bartlett's test revealed heterogeneity of variance. Statistical analysis was conducted by SAS for Windows (SAS Institute, Inc., Cary, NC, USA). There was a significant effect of treatment and category (P &lt; 0.001), but there were no treatments-by-category interactions (P &gt; 0.05). A new follicular wave was induced in all animals after treatment with EB or EV. The heifers given G2EB (2.50 � 0.19a; 2 to 3x days) had a reduced (P &lt; 0.01) and least variable interval (P &lt; 0.05) than those given G2.5EV (4.20 � 0.27b; 3 to 6xy days) or G5EV (6.10 � 0.57c; 3 to 8y days). The cows given G5EV (4.00 � 0.52b; 2 to 6y days) had the longest (P = 0.05) and more variable interval (P &lt; 0.001) than those given G2EB (2.50 � 0.22a; 2 to 4x days), but were similar to those given G2.5EV (3.10 � 0.41ab; 2 to 6xy days). The effect of EB was similar in heifers and cows (P &gt; 0.05); however, the EV or 2.5EV promoted a longer emergence wave interval in the heifers than in the cows (P &lt; 0.05). Analyzing the main effects, cows and heifers given G2EB (2.50 � 0.15a; 2 to 4x days) had a smaller and less variable interval than those given G2.5EV (3.65 � 0.27b; 2 to 6y) or G5EV (5.05 � 0.44c; 2 to 8z). In conclusion, the EV treatment, in both doses (5 or 2.5 mg), resulted in a delayed and more variable interval to emergence of a new follicular wave than 2 mg of EB in Bos indicus cows and heifers treated with a Norgestomet auricular implant. This work was supported by Intervet, Brazil.

Induction of a new follicular wave in holstein heifers synchronized with norgestomet

Treatments with progestin to synchronize the bovine estrous cycle in the absence of the corpus luteum, induces persistence of a dominant follicle and a reduction of fertility at doses commonly utilized. The objective of the present research was to induce a new wave of ovarian follicular development in heifers in which stage of the estrous cycle was synchronized with norgestomet. Holstein heifers ( n=30) were used, in which estrus was synchronized using two doses of PGF 2α i.m. (25 mg each) 11 days apart. Six days after estrus (day 0=day of estrus) heifers received a norgestomet implant (6 mg of norgestomet). On day 12, heifers were injected with 25 mg of PGF 2α i.m. and assigned to treatments (T1 to T4) as follows: treatment 1, heifers received a second norgestomet implant (T1: N+N, n=6), treatment 2, received 100 μg of GnRH i.m. (T2: N+GnRH, n=6), treatment 3, 200 mg of progesterone i.m. (T3: N+P 4, n=6), treatment 4, control treatment with saline solution i.m. (T4: N+SS); in the four treatments (T1 to T4) implants were removed on day 14. For treatment 5, heifers received 100 μg of GnRH i.m. on day 9 and 25 mg of PGF 2α i.m. (T5: N+GnRH+PGF 2α) at the time of implant removal (day 16). Ovarian evaluations using ultrasonographic techniques were performed every 48 h from days 3 to 11 and every 24 h from days 11 to 21. Blood samples were collected every 48 h to analyze for progesterone concentration. A new wave of ovarian follicular development was induced in 3/6, 6/6, 3/6, 1/6 and 6/6, and onset of estrus in 6/6, 0/6, 6/6, 6/6 and 6/6 for T1, T2, T3, T4 and T5, respectively. Heifers from T1, T3 and T4 that ovulated from a persistent follicle, showed estrus 37.5±12.10 h after implant removal and heifers that developed a new wave of ovarian follicular development showed it at 120.28±22.81 h ( P<0.01). Ovulation occurred at 5.92±1.72 and 2.22±1.00 days ( P<0.01), respectively. Progesterone concentration was <1 ng/ml from days 7 to 15 in T1, T2 and T4; for T3 progesterone concentration was 2.25±0.50 ng/ml on day 13 and decreased on day 15 to 0.34±0.12 ng/ml ( P<0.01). For T5, progesterone concentration was 1.66±0.58 ng/ml on day 15. The more desirable results were obtained with T5, in which 100% of heifers had a new wave of ovarian follicular development induced, with onset of estrus and ovulation synchronized in a short time period.

Comparison of different protocols used to induce and synchronize estrus cycle of Saanen goats

The objective of the present study was to determine the efficiency of different protocols in inducing and synchronizing the estrus cycle of Saanen goats by using new or reused synchro-mate-B (SMB) and controlled internal drug release (CIDR) in combination with either equine chorionic gonadotrophin (eCG) or cloprostenol. Female goats ( n=120) were divided at random into six groups of 20 animals each. In the T1-SMB group, the females were injected intramuscularly (i.m.) with 2.5 mg estradiol valerate+1.5 mg norgestomet and received a subcutaneous ear implant containing 2.0 mg of norgestomet for 9 days. On the day of implant removal, the animals received 100 IU of eCG and 0.05 mg of cloprostenol. In the T2-SMB group, the animals were identically treated, except that the ear implant they received had been previously used in cattle. In the T3-SMB group, the treatment was identical to that for T1-SMB, but eCG was not administered. In the T1-CIDR group, the animals were treated for 9 days with an intravaginal device inpregnated with 0.3 g of progesterone and injected i.m. with 100 IU of eCG and 0.05 mg of cloprostenol on the day of implant removal. The animals of the T2-CIDR group were treated like those of the T1-CIDR group, except that the intravaginal implant they received had been previously used in goats. The animals of the T3-CIDR group were treated like those of the T1-CIDR group, but did not receive eCG. The percentages of estrus and fertility were 100/80% (T1-SMB), 90/80% (T2-SMB), 75/75% (T3-SMB), 100/95% (T1-CIDR), 100/100% (T2-CIDR) and 70/65% (T3-CIDR), respectively, with the results for both parameters being lower ( P≤0.05) in the T3-SMB and T3-CIDR groups. It is concluded that auricular implants or intravaginal devices may be reused, at last one more time, because they are efficient for inducing and synchronizing estrus in cyclic dairy goats.

Estrous synchronization with norgestomet and estradiol valerate at the end of lactation accelerates drying off in goats

Sixty-one crossbred criollo multiparous goats kept under range conditions, were used to determine the effect of estrous synchronization with implants of Syncro-Mate-B (SMB; approximately 2 mg of norgestomet), at the beginning, peak and end of lactation, on milk production and composition. The SMB implant was applied for 9 d, and an intramuscular injection of 1 mg estradiol valerate (EV) and 0.75 mg norgestomet were administered concurrently with the insertion of the implant. Treatment for estrous synchronization at the beginning and peak of lactation did not affect milk yield at the post-treatment measurement. Also, the length of lactation (210 d) and total milk yield (112.3 ±23 l, 99 ±18 l and 102 ±24 l for control animals, goats treated at the beginning and peak of lactation, respectively) were not influenced by the estrous synchronization treatment at the beginning and peak of lactation. The percentage of protein and casein was 10% higher ( p<0.05) at the post-treatment measure in the milk of steroids-treated goats at the beginning of lactation than the pre-treatment measurement. Milk yield at the post-treatment measurement of goats treated at the end of lactation was 67% less than the pre-treatment measurement ( p<0.05), and these goats dried off shortly after the removal of the SMB implant. Mean fat concentration was significantly lower ( p<0.05) at the post-treatment measurement among goats treated at the end of lactation than untreated goats. Lactation length was 10 d shorter for goats treated with SMB and EV at the end of lactation than control goats. Consequently total milk yield was 28% lower for goats treated at the end of lactation compared with the untreated animals. These data suggest that the administration close to the end of lactation, of norgestomet and EV for estrous synchronization of goats kept under range conditions, hastens involution of the mammary tissue.

Synchronization of estrus and ovulation and associated endocrine changes in [formula omitted] cows

The effects of 4 estrus synchronization treatments on intervals to and synchrony of estrus and ovulation, on timing of the preovulatory LH surge and associated changes in plasma progesterone, LH, FSH, and 17β-estradiol (E 2) were investigated in 48 Bos indicus cows. Treatment 1 consisted of 2 injections of PGF 2α 14 d apart (n = 12); Treatment 2 of a subcutaneous 3-mg norgestomet implant and an intramuscular injection of 3 mg of norgestomet and 5 mg estradiol valerate, with the implant removed 10 d later (n = 12; norgestomet-estradiol); Treatment 3 of norgestomet-estradiol, with a subcutaneous injection of PMSG given at time of implant removal (Day 10; n = 12); and Treatment 4 of norgestomet implant (as for Treatments 2 and 3) inserted for 10 d, with an intramuscular injection of PGF 2α given at the time of implant removal (n = 12). The experiment was conducted in 2 replicates (24 cows/replicate, 6 cows/group). Estrus, ovulation and timing of the preovulatory surge of LH varied less in cows treated with norgestomet-estradiol and PMSG than in cows in Treatments 1 and 4 (P < 0.008). Treatment with PMSG reduced variation in ovulation times and timing of the LH surge in cows treated with norgestomet-estradiol (P < 0.02). Concentrations of E 2 were higher in cows in Treatments 2 and 3 on the final day of treatment and at about 6 h post ovulation compared with cows in Treatments 1 and 4 (P < 0.05). Different methods for synchronizing estrus did not alter sequential endocrine and behavioral changes in relation to the timing of the LH peak, and the results were consistent with current recommendations for insemination times in Bos taurus cattle.

Absence of response to oestrus induction and synchronization treatment is related to lipid mobilization in suckled beef cows.

Energy status, follicular growth, oestradiol and LH secretion were investigated in 17 suckled Charolais cows synchronised 59.0 +/- 3.6 days after calving with a 10 day ear implant containing 3 mg of Norgestomet. The cows received 3 mg of Norgestomet and 5 mg of oestradiol valerate by IM injection at implant insertion (day 0) and 600 IU PMSG at implant removal (day 10). They were artificially inseminated (AI) 48 and 72 h after implant removal. Energy status was assessed by measuring weekly plasma concentrations of non-esterified fatty acids (NEFA), beta hydroxy-butyrate (BHB), glucose and insulin 7 weeks before AI. Progesterone plasma concentrations were measured during the same period to assess the presence of a functional corpus luteum. Follicular growth was followed daily by ultrasonography from day -3 to day 13. Oestradiol secretion was measured on day -3, day 6 and day 10 from five hourly samples. Oestradiol and LH plasma concentrations were measured hourly from 29 to 48 h after implant removal for seven cows. Cows were checked for pregnancy by ultrasonography 45 days after AI. Pregnant cows (P) were compared with non-pregnant cows (NP) for energy status, follicular growth, and oestradiol secretion by split-plot ANOVA. Two cows (11.8%) were cyclic before treatment, seven ovulated after treatment (41.2%) and five were found pregnant 45 days after AI (29.4%). There was no difference in body condition score and body weight between P and NP cows on day 0 (2.5 +/- 0.2 and 685 +/- 24 kg vs 2.5 +/- 0.1 and 670 +/- 13 kg; P > 0.05). Mean plasma NEFA concentrations before treatment were significantly lower in P than in NP cows (218 +/- 29 mu eq/L vs 279 +/- 18 mu eq/L; P < 0.05). No significant differences between P and NP cows were found for BHB, glucose and insulin concentrations. P cows presented more medium sized follicles (5 mm < or = diameter < 10 mm) than NP females during the period of observation (2.65 +/- 0.19 vs 2.50 +/- 0.12; P = 0.05). Plasma oestradiol concentrations were not different between P and NP cows on day -3 (8.4 +/- 0.7 pg/mL vs 7.7 +/- 0.4 pg/mL, P > 0.05), day 6 (10.4 +/- 0.6 pg/mL vs 9.8 +/- 0.4 pg/mL, P > 0.05) but were higher in P than in NP cows on day 10 (10.9 +/- 0.6 pg/mL vs 7.8 +/- 0.4 pg/mL; P < 0.05). After implant removal, oestradiol secretion only increased in P cows and a LH peak occurred whereas no increases in oestradiol (11.0 +/- 0.4 pg/mL vs 6.3 +/- 0.3 pg/mL, P < 0.05) and LH (6.0 +/- 0.5 ng/mL vs 1.2 +/- 0.5 ng/mL, P < 0.05) secretion were observed in NP cows. The conclusion was that follicular growth, oestradiol secretion, ovulation and pregnancy rate after oestrus synchronisation treatment are related to mobilization of energy stores before treatment in suckled beef cows in the same body condition score.

Norgestomet implants prevent pregnancy in beef heifers on pasture.

The efficacy of erodible norgestomet implants for preventing pregnancy in postpubertal heifers was evaluated in two experiments at five locations each. Heifers (n = 896) within each study location were stratified by weight and allotted randomly to receive an ear implant containing either 0, 24, 36, or 48 mg of norgestomet (d 0). Heifers were exposed to fertile bulls immediately after implantation for 75 d (d 0 to 74) in Exp. 1 (n = 476) or for 80 d (d 75 to 154) in Exp. 2 (n = 420). Weights were recorded on d 0 and 74 (Exp. 1 and 2) and d 154 (Exp. 2). Each heifer was palpated rectally for pregnancy at the end of each experiment. Pregnancy rates were higher (P < .01) for control heifers (0 mg implant) than for heifers that received 24, 36, or 48 mg of norgestomet. In Exp. 1, pregnancy rates were 96, 29, 6, and 4% for heifers that received 0, 24, 36, and 48 mg implants of norgestomet, respectively. In Exp. 2, pregnancy rates were 85, 36, 19, and 9% for heifers that received 0, 24, 36, and 48 mg implants of norgestomet, respectively. Estrous activity during the first 3 wk of bull exposure was reduced (P < .05) among heifers that received norgestomet implants compared to control heifers but was not completely abolished at any dosage in Exp. 1. During the first 75 d of Exp. 1 and 2, heifers treated with 36 or 48 mg norgestomet implants gained weight faster (P < .05) than control heifers. Combined across both experiments, ADG during the first 74 d were .53, .56, .59, and .60 kg/d for heifers treated with 0, 24, 36, and 48 mg implants of norgestomet, respectively. These data indicate that norgestomet implants increased rate of weight gain, reduced estrous activity, and reduced the occurrence of pregnancy in heifers on pasture.