COMPARISON OF LONG-TERM PROGESTERONE-BASED PROTOCOL ON REPRODUCTIVE PERFORMANCE OF PREPUBERTAL AND PUBERTAL BEEF HEIFERS.

The aim of this study was to investigate estrus synchronization in prepubertal and pubertal heifers (crossbred ½ Nelore x Red Angus - commercial herd) submitted to a long-term progesterone-based protocol for timed artificial insemination (TAI), as well as overall pregnancy rates. Four hundred forty-seven heifers underwent ultrasound examination of the ovaries and were assigned to one of 3 groups: (1) prepubertal heifers (PPNS; n = 114) with ovarian follicles 8 mm in diameter and/or a CL that underwent the same protocol as PPTAI heifers. Overall pregnancy rate was determined by transrectal ultrasonography on d 45 after NS or TAI. Data were analyzed using the FREQ procedure of SAS (SAS Inst. Inc., Cary, NC). Pregnancy rates were as follows: 20.1% in PPNS, 37.0% in PPTAI, and 48.5% in PTAI (P < 0.05). In conclusion, TAI after estrus synchronization with a hormonal protocol using EB and ECP in prepubertal and pubertal heifers resulted in higher pregnancy rates than prepubertal heifers exposed to natural service, and exposure of prepubertal heifers to a long-term progesterone-based protocol effectively synchronized estrus

CORRELAÇÃO ENTRE A BIOMETRIA TESTICULAR, A IDADE E AS CARACTERÍSTICAS REPRODUTIVAS DE TOUROS DA RAÇA NELORE

O objetivo da pesquisa foi o de correlacionar a dinâmica de crescimento da biometria testicular com as características espermáticas em animais em fase de crescimento e destinados à reprodução. Foram utilizados 20 animais da raça Nelore entre 10 e 24 meses de idade, criados sob condições extensivas de pastoreio e com suplementação mineral. Constituíram-se dois grupos (G), sendo o G1 (n=10) formado por animais com a idade variando de 10 a 18 meses e o G2 (n=10) por animais com idade entre 18,1 e 24 meses ao início do experimento. Por um período de dez meses, em três distintos momentos experimentais, com intervalos de cinco meses entre eles, nos animais de ambos os grupos, realizou-se a aferição do peso corporal, mensurações da circunferência escrotal (CE), além de avaliação do vigor, motilidade e concentração espermáticas.  Houve influência da idade e do desenvolvimento corporal sobre as características reprodutivas estudadas. Ao se comparar o crescimento testicular, verificou-se que os animais do G1, tiveram maior proporção de crescimento biométrico testicular (P<0,001) que os animais do G2; a concentração espermática foi constantemente maior nos animais do G2, nos três momentos estudados (P<0,001), porém os grupos não diferiram quanto ao vigor e a motilidade espermática em todo o período experimental.The aim of the present experiment was to establish an interrelationship between the testicular and spermatic biometry of young bulls for breeding. Twenty bulls of the Nelore bred, between 10 and 24 months were used. The animals a monthly measurement of the perimetral scrotum and vigor, motility and sperm concentration were submitted. During the experimental period bulls lived under pasturage conditions with mineral supplement. The experimental bulls were divided in two groups: G1 formed by 10 animals, aging from 10 to 18 months, and G2, also with 10 animals but aging 18,1 to 24 months. The evaluated reproductive parameters allowed conclude that both age and body development may exert influence on the studied reproductive characteristics. By comparison of both groups in regard to the age, it has been found that the animals from the G1 disclosed a superior testicular biometric development (p<0.001) than the bulls from the G2, the sperm concentration increased in G2, as they age increased (p<0.001). The vigor and the sperm motility did not affected by the age in the period

Comparison between temporary weaning versus equine chorionic gonadotropin protocols after treatment with intravaginal progesterone for timed artificial insemination in Bos taurus indicus cows

O objetivo do estudo foi comparar a eficiência reprodutiva utilizando dois protocolos com desmame temporário de bezerros e a gonadotrofina coriônica equina (eCG), visando a sincronização do estro e da ovulação na inseminação artificial em tempo fixo (IATF). Um total de 534 vacas multíparas Bos taurus indicus foram distribuídas em três grupos: grupo desmame temporário (DT) no dia 8 do protocolo (GDT8; n=225); grupo DT no dia 9 (GDT9; n=139) e grupo gonadotrofina coriônica equina (GeCG, n=170). O GDT8 recebeu no dia zero (d0) um dispositivo intravaginal com progesterona (P4; 0,558g) + benzoato de estradiol (BE; 2mg, im). No d8, houve a remoção do dispositivo, injeção de PGF (0,075mg, im) + cipionato de estradiol (CE; 0,5mg, im) + DT por 48 horas. No d10, executou-se a IATF e o retorno dos bezerros às mães. O GDT9 foi submetido a idêntico protocolo do GDT8, exceto a remoção do dispositivo, o DT, aplicação da PGF e do CE, que ocorreu no dia 9. No d11 foi realizada IATF e a volta dos bezerros às mães. O GeCG foi submetido a idêntico protocolo ao do GDT8, exceto que no d8 recebeu a eCG, no d9 o BE (1mg, im) e a IATF no d10. O diagnóstico de gestação foi feito no d45 (ultrassonografia). As vacas não-prenhes (pós IATF) foram re-inseminadas sob a observação do estro (IA convencional). As vacas não-prenhes remanescentes da IA convencional, permaneceram com o touro por outros 45 dias. As taxas de prenhez após a IATF foram de 47,1 (GDT8), 40,2 (GDT9) e 51,7% (GeCG)(p=0,13); já a TP após IA convencional foi de 19,3; 31,3 e 26,8 %. As taxas de prenhez ao final da estação reprodutiva resultaram em 95,1; 90,6, e 92,3% respectivamente para GDT8, GDT9 e GeCG. Concluiu-se, que não houve diferença na eficiência reprodutiva na IATF entre os protocolos aplicados; o emprego do DT ou da eCG pode ser adotado na estação reprodutiva de vacas de corte.The aim of the study was to compare the reproductive efficiency of two protocols with temporary weaning (TW) of calves and one using equine chorionic gonadotropin (eCG), the synchronization of estrus and ovulation in timed artificial insemination (TAI) protocol. A total of 534 multiparous cows were distributed into three groups: temporary weaning on day 8 of the protocol group (TW8G; n = 225); temporary weaning on day 9 group (TW9G; n = 139) and equine chorionic gonadotropin group (eCGG, n = 170). TW8G received on day zero (d0) an intravaginal device with progesterone (P4; 0.558g) + estradiol benzoate (EB; 2mg, im). On d8, the device was removed with P4 + PGF (0.075mg, im) + estradiol cypionate (EC 0.5 mg, im) + removal of the calf for 48 hours. On d10, TAI was performed, and the calves returned to their mothers. The TW9G was subjected to the same protocol as the TW8G, except for the removal of the device with the P4, which occurred on the 9th, and on the d11, TAI was performed, and the calves returned to their mothers. eCGG was subjected to the same protocol as TW8G, except that on d8 it received eCG (300IU, im), on d9 estradiol benzoate and TAI on d10. The pregnancy diagnosis was made change for done at d45. The non-pregnant cows (post TAI) were re-inseminated under the observation for estrus observation (conventional AI). The remaining empty cows from conventional AI remained with the bull for another 45 days. PR after TAI was 47.1 (TW8G), 40.2 (TW9G) and 51.7% (GeCG), while PR after conventional AI was 19.3%; 31.3% and 26.8%. PR at the end of the breeding season resulted in 95.1, 90.6, and 92.3% respectively for TW8G, TW9G and eCGG. It was concluded that there was no difference in reproductive efficiency in the timed artificial insemination between the applied protocols; the use of TW or eCG can be implemented in the breeding season of beef cows

Efficiency and accuracy of different ovulation inducers after progesterone device removal in crossbred multiparous cows

The aim of this study was to verify the efficiency and ovulation time after the administration of different inducers for synchronization of ovulation in beef cows. One hundred and eight non-lactating cows were distributed into the control group (CG; untreated; n=28), estradiol benzoate (EB) group (EBG; n=28); 17 beta-estradiol (17ßE) group (17ßEG; n=28), and deslorelin (DES) group (DESG; n=24). On day minus 11 (D-11) of the protocol, the CG underwent application of cloprostenol and ultrasound examination (US); on D0, progesterone (P4) was inserted plus EB; on D7, cloprostenol was applied; on D9, P4 was removed and cloprostenol plus 400 IU of equine chorionic gonadotropin (eCG) was injected. The EBG was subjected to treatment identical to that of the CG, except on D10, when the cows received EB. The 17ßE was subjected to the same protocol used in the CG except for the administration of 17ßE on D10. And, the DESG was subjected to the same treatment as the CG, except on D10, when the group received DES acetate. Twelve hours after the administration of EB, 17ßE and DES, ovarian US were performed every 6 hours. The preovulatory follicle (POF) diameters measured before ovulation were 19.5; 14.7; 18.7 and 19.8 mm respectively for CG, EBG, 17ßEG and DESG; and the time intervals between inducer application and ovulation were 20.2; 18.9; 21.0 and 22.5 hours respectively. In conclusion, all ovulation inducers were efficient in promoting ovulation; the inducers caused ovulation between 18.9 and 22.5 hours; EB promoted ovulation in a shorter time (P<0.05); 17ßE and DES showed greater variation in application/ovulation time between groups. Keywords: Ovulation inductors; Deslorelin acetate; Cows; Ovulation synchronization; 17 beta-estradiol

REDUCTION OF THE VOLUNTARY WAITING PERIOD BY USE OF HORMONAL PROTOCOLS AND FIXED-TIME ARTIFICIAL INSEMINATION (FTAI) IN DAIRY COWS

ABSTRACT: The aim of this study was to reduce the waiting voluntary period in dairy cows by administration of two different hormonal protocols for estrus synchronization and fixed-time artificial insemination (FTAI). One hundred twenty-eight Holstein dairy cows were studied. Three groups (G) were carried out: G1 (44 treated), G2 (34 treated) and G3 (50 as control). In the treated cows the following hormonal protocols was applied between 40 and 45 days post partum: G1- Day 0 (D0) - bovine intravaginal device containing progesterone (P4) plus 1.0 mg of estradiol benzoate (EB), D8 - removal of the P4, plus 0.5 mg of cloprostenol plus 400 IU of equine chorionic gonadotropin (eCG), D9 - 1.0 mg of EB and FTAI after 36 hours. G2 - D0 - P4 intravaginal plus 50 mcg of gonadotropin-releasing hormone (GnRH), D7 - removal of the P4 plus cloprostenol plus 400 IU eCG; D9 - 50 mcg of GnRH and FTAI 16 hours after. G3 – Control group inseminated 12 hours after the visual estrus. Results: G1 and G2 were inseminated (FTAI) respectively in the D55.5 and D56.8 after calving, while the G3 in the D84.5 (p0.05).  In Conclusion: there was significant reduction in the voluntary waiting period in treated cows and higher pregnancy rate although not significant.ABSTRACT: The aim of this study was to reduce the waiting voluntary period in dairy cows by administration of two different hormonal protocols for estrus synchronization and fixed-time artificial insemination (FTAI). One hundred twenty-eight Holstein dairy cows were studied. Three groups (G) were carried out: G1 (44 treated), G2 (34 treated) and G3 (50 as control). In the treated cows the following hormonal protocols was applied between 40 and 45 days post partum: G1- Day 0 (D0) - bovine intravaginal device containing progesterone (P4) plus 1.0 mg of estradiol benzoate (EB), D8 - removal of the P4, plus 0.5 mg of cloprostenol plus 400 IU of equine chorionic gonadotropin (eCG), D9 - 1.0 mg of EB and FTAI after 36 hours. G2 - D0 - P4 intravaginal plus 50 mcg of gonadotropin-releasing hormone (GnRH), D7 - removal of the P4 plus cloprostenol plus 400 IU eCG; D9 - 50 mcg of GnRH and FTAI 16 hours after. G3 – Control group inseminated 12 hours after the visual estrus. Results: G1 and G2 were inseminated (FTAI) respectively in the D55.5 and D56.8 after calving, while the G3 in the D84.5 (p0.05).  In Conclusion: there was significant reduction in the voluntary waiting period in treated cows and higher pregnancy rate although not significant

Impact of Equine Chorionic Gonadotropin Associated with Temporary Weaning, Estradiol Benzoate, or Estradiol Cypionate on Timed Artificial Insemination in Primiparous Bos Indicus Cows

The study aimed to determine the impact of equine chorionic gonadotropin (eCG) associated with different timed artificial insemination (TAI) protocols on the pregnancy rate (PR) in Bos indicus cows previously treated with progesterone. Five hundred and fifty-seven primiparous cows were subjected to the following treatments: on day 0 (d0), GeCGTW (group equine Chorionic Gonadotropin+Temporary Weaning;n=178) received 0,558 g intravaginal progesterone (P4)+1.0 mg of estradiol benzoate (EB) (IM); on d8 (P4 removal+0,075 mg D-cloprostenol + 400 IU eCG + TW for 48 h); on d10, TAI + calves return to dam; GeCGEB (group equine Chorionic Gonadotropin+Estradiol benzoate; n=176) the same as GeCGTW without TW + application of 1.0 mg of EB on d9; GeCGEC (group equine Chorionic Gonadotropin+Estradiol Cypionate; n=203), the same as GeCGTW without TW+1.5 mg EC (IM). On d35, post TAI, pregnancy diagnosis (PD) was performed. Non-pregnant animals remained under clean-up bulls for 90 days. After this period, the animals were subjected to PD using ultrasound. The PR of TAI was 51.1%, 47.1%, and 47.8% for GeCGTW, GeCGEB24, and GeCGEC (P>0.05) respectively. The PR under clean-up bulls was 88.3%, 47.3%, and 31.1% (P<0.05). The final PR (TAI+clean-up bulls) of the groups was 94.4%, 72.1%, and 64.0%, respectively (P<0.05). It was concluded that no differences in PR among the protocols related to TAI were detected; PR in the GeCGTW protocol under clean-up bulls was higher compared to others (P<0.05); the overall PR of cows subjected to TAI+clean-up bulls was significantly higher in GeCGTW than in the other groups