Análise econômica de dois protocolos para inseminação artificial em tempo fixo (IATF) em novilhas de corte / Economic analysis of two protocols for fixed-time artificial insemination (FTAI) in beef heifers

Foram avaliadas 731 novilhas de corte submetidas à inseminação artificial em tempo fixo (IATF) aolongo de três anos. Os protocolos fundamentaram-se na inserção de um dispositivo intravaginal de progesterona(DIP) e aplicação de benzoato de estradiol e PGF2α (PEPE - 428) ou aplicação do protocolo Ovsynch modificadopela inserção de um DIP por sete dias (OVSP4 - 303). A avaliação econômica levou em consideração valoresreais de mercado em maio/2015. Os dados foram analisados com o programa SPSS. As taxas de prenhez para osgrupos PEPE e OVSP4 foram, respectivamente, de 30,1% e 46,7% no ano 1 (P < 0 ,05), 44,8% e 48,0% no ano 2e 34,7% e 57,6% no ano 3 (P < 0,05). O valor da prenhez para os respectivos grupos e anos foi de R$ 79,24 e R$59,10, R$ 53,24 e R$ 57,50 e R$ 68,73 e R$ 47,94. Na média dos anos, a taxa de prenhez foi de 39,0% para ogrupo PEPE e de 51,5% para o grupo OVSP4 (P < 0,01), com respectivo valor da prenhez de R$61,15 e R$53,59. A modificação do protocolo Ovsynch, pela inserção do DIP, resultou em taxa de prenhez satisfatória emelhor resposta econômica para novilhas de corte.(AU)

Data from 731 beef heifers submitted to fixed-timed artificial insemination (FTAI) along of three yearswere evaluated. Two protocols were utilized. The protocol called PEPE is based on the insertion of anintravaginal progesterone device (IPD) and injections of estradiol benzoate and PGF2α (428 animals). Theprotocol called OvsynchP4 was modified by insertion of IPD for seven days (303 animals). The economicanalysis considered values of the market in may/2015. The data were analyzed with the program SPSS. Thepregnancy rate in the PEPE and OVSP4 groups were, respectively, 30,1% and 46,7% in the first year (P <0,05), 44,8% and 48,0% in the second year 2 and 34,7% and 57,6% in the third year 3 (P < 0,05).Thepregnancy costs to the respective groups and years were R$ 79,24 and R$ 59,10, R$ 53,24 and R$ 57,50 and R$68,73 and R$ 47,94. The average pregnancy rate was 39,0% in the PEPE and 51,5% in the OVSP4 (P < 0,01),with respective pregnancy cost of R$ 61,15 and R$ 53,59. The OvsynchP4 protocol, modified by insertion of asIPD, results in satisfactory pregnancy rate and better economic results in beef heifers.(AU)

Análise econômica de dois protocolos para inseminação artificial em tempo fixo (IATF) em novilhas de corte / Economic analysis of two protocols for fixed-time artificial insemination (FTAI) in beef heifers

Foram avaliadas 731 novilhas de corte submetidas à inseminação artificial em tempo fixo (IATF) aolongo de três anos. Os protocolos fundamentaram-se na inserção de um dispositivo intravaginal de progesterona(DIP) e aplicação de benzoato de estradiol e PGF2α (PEPE - 428) ou aplicação do protocolo Ovsynch modificadopela inserção de um DIP por sete dias (OVSP4 - 303). A avaliação econômica levou em consideração valoresreais de mercado em maio/2015. Os dados foram analisados com o programa SPSS. As taxas de prenhez para osgrupos PEPE e OVSP4 foram, respectivamente, de 30,1% e 46,7% no ano 1 (P < 0 ,05), 44,8% e 48,0% no ano 2e 34,7% e 57,6% no ano 3 (P < 0,05). O valor da prenhez para os respectivos grupos e anos foi de R$ 79,24 e R$59,10, R$ 53,24 e R$ 57,50 e R$ 68,73 e R$ 47,94. Na média dos anos, a taxa de prenhez foi de 39,0% para ogrupo PEPE e de 51,5% para o grupo OVSP4 (P < 0,01), com respectivo valor da prenhez de R$61,15 e R$53,59. A modificação do protocolo Ovsynch, pela inserção do DIP, resultou em taxa de prenhez satisfatória emelhor resposta econômica para novilhas de corte.

Data from 731 beef heifers submitted to fixed-timed artificial insemination (FTAI) along of three yearswere evaluated. Two protocols were utilized. The protocol called PEPE is based on the insertion of anintravaginal progesterone device (IPD) and injections of estradiol benzoate and PGF2α (428 animals). Theprotocol called OvsynchP4 was modified by insertion of IPD for seven days (303 animals). The economicanalysis considered values of the market in may/2015. The data were analyzed with the program SPSS. Thepregnancy rate in the PEPE and OVSP4 groups were, respectively, 30,1% and 46,7% in the first year (P <0,05), 44,8% and 48,0% in the second year 2 and 34,7% and 57,6% in the third year 3 (P < 0,05).Thepregnancy costs to the respective groups and years were R$ 79,24 and R$ 59,10, R$ 53,24 and R$ 57,50 and R$68,73 and R$ 47,94. The average pregnancy rate was 39,0% in the PEPE and 51,5% in the OVSP4 (P < 0,01),with respective pregnancy cost of R$ 61,15 and R$ 53,59. The OvsynchP4 protocol, modified by insertion of asIPD, results in satisfactory pregnancy rate and better economic results in beef heifers.

Efeito da aplicação de benzoato de estradiol ou da Gonadotrofina Coriônica humana em protocolos de ressincronização da ovulação sobre a prenhez da IATF / Effects of estradiol benzoate or human Chorionic Gonadotropin for ovulation resynchronization protocols on pregnancy rate per TAI

Background: Programs of resynchronization of ovulation have the objective of allowing reinsemination of females that did not get pregnant after fixed time artificial insemination (TAI), in the lowest time interval possible. These protocols are usually composed of administration of estradiol benzoate (EB) concomitant to the insert of progesterone-based (P4) intravaginal implants 22 to 24 days after the first TAI. However, little information is available on the impact of hormonal manipulation in a pre-established pregnancy. The objective of this study was to evaluate if resynchronization of ovulation, started 24 days after the first TAI, would interfere in the function of the corpus luteum (CL), production of P4, and pre-established pregnancy.Materials, Methods & Results: For this study, 526 Brangus heifers with ages between 24 and 26 months, were subjected to TAI program in the beginning of the breeding season. Synchronization protocol for the first TAI started with insertion of an intravaginal implant containing 750 mg of P4 and administration of 2 mg of estradiol benzoate (EB) intramuscular (im) on day -9 (D-9). After seven days (D-2), P4 implants were removed, and 150 µg of D-cloprostenol (PGF), i.m., and 1 mg of estradiol cypionate (EC), i.m., were administered. The TAI was performed between 48 and 54 h after removal of the P4 implant (D0). Twenty-four days after the first TAI (D24), heifers were randomly divided into the following experimental groups: Control (n = 167, no treatment), EB (n = 208, 1 mg of EB, i.m.), and hCG (n = 151, 1000 IU of hCG, i.m.). Heifers of EB and hCG groups received a new intravaginal device containing 750 mg of P4 on D24. On day 31 (D31), P4 implants were removed and pregnancy diagnosis were performed by ultrasound. Pregnancy rates from the first TAI on D31 were 58.7% (98/167), 53.4% (111/208) and 52.9% (80/151) respectively for groups Control, EB and hCG.[...](AU)

Efeito da aplicação de benzoato de estradiol ou da Gonadotrofina Coriônica humana em protocolos de ressincronização da ovulação sobre a prenhez da IATF / Effects of estradiol benzoate or human Chorionic Gonadotropin for ovulation resynchronization protocols on pregnancy rate per TAI

Background: Programs of resynchronization of ovulation have the objective of allowing reinsemination of females that did not get pregnant after fixed time artificial insemination (TAI), in the lowest time interval possible. These protocols are usually composed of administration of estradiol benzoate (EB) concomitant to the insert of progesterone-based (P4) intravaginal implants 22 to 24 days after the first TAI. However, little information is available on the impact of hormonal manipulation in a pre-established pregnancy. The objective of this study was to evaluate if resynchronization of ovulation, started 24 days after the first TAI, would interfere in the function of the corpus luteum (CL), production of P4, and pre-established pregnancy.Materials, Methods & Results: For this study, 526 Brangus heifers with ages between 24 and 26 months, were subjected to TAI program in the beginning of the breeding season. Synchronization protocol for the first TAI started with insertion of an intravaginal implant containing 750 mg of P4 and administration of 2 mg of estradiol benzoate (EB) intramuscular (im) on day -9 (D-9). After seven days (D-2), P4 implants were removed, and 150 µg of D-cloprostenol (PGF), i.m., and 1 mg of estradiol cypionate (EC), i.m., were administered. The TAI was performed between 48 and 54 h after removal of the P4 implant (D0). Twenty-four days after the first TAI (D24), heifers were randomly divided into the following experimental groups: Control (n = 167, no treatment), EB (n = 208, 1 mg of EB, i.m.), and hCG (n = 151, 1000 IU of hCG, i.m.). Heifers of EB and hCG groups received a new intravaginal device containing 750 mg of P4 on D24. On day 31 (D31), P4 implants were removed and pregnancy diagnosis were performed by ultrasound. Pregnancy rates from the first TAI on D31 were 58.7% (98/167), 53.4% (111/208) and 52.9% (80/151) respectively for groups Control, EB and hCG.[...]

Administration of human chorionic gonadotropin to improve luteal function in lactating beef cattle / Administração de gonadotrofina coriônica humana para estimulação da função luteal em vacas de corte lactantes

Background: Pregnancy rate after fixed-time artificial insemination (FTAI) in beef cattle is affected by ovulation rate,luteal function and embryo survival. Cows in early post partum period frequently have low progesterone productionand short luteal phases. Treatments using human chorionic gonadotropin (hCG) after FTAI have been tested in aneffort to increase progesterone concentration, improve embryo development and consequently pregnancy rates. Theobjectives of this work were to evaluate the effects of administration of hCG on day 4 after FTAI on induction ofovulation of the first dominant follicle, corpus luteum (CL) development, progesterone production and pregnancyrate in lactating beef cows.Materials, Methods & Results: Five hundred and sixty nine multiparous Angus suckled beef cows, 45-70 dayspostpartum, were synchronized to FTAI. On day -9, intravaginal implants containing 0,750 g of progesterone wereinserted and 2mg of estradiol benzoate administered, im. Seven days later, cows had their implants removed andwere injected with 150 µg of d-cloprostenol, im, and 1 mg of estradiol cipionate, im. Cows were inseminated 52-56h after implant removal. Four days later, cows were assigned into two groups, hCG (1500 UI of hCG, im, n = 269) orControl (1,5 mL saline, im, n = 300). Blood samples were collected on days 4, 7, 10 and 14 after FTAI for analysisof serum progesterone concentration by radioimmunoassay. Ovarian ultrasonographic exams were done on day 0 todetermine the diameter of ovulatory follicle (OF), on day 4 to measure the diameter of the first dominant follicle and,on day 7, to determine the CL area (cm2) and the number of accesory CL. Pregnancy diagnosis were done on day 30.Pregnancy rates were compared by chi-square test, progesterone concentration and CLs parameters were comparedby student-t test. The administration of hCG resulted in higher serum progesterone concentration, improved CL areaand the frequency of accessory CL...

Administration of human chorionic gonadotropin to improve luteal function in lactating beef cattle / Administração de gonadotrofina coriônica humana para estimulação da função luteal em vacas de corte lactantes

Background: Pregnancy rate after fixed-time artificial insemination (FTAI) in beef cattle is affected by ovulation rate,luteal function and embryo survival. Cows in early post partum period frequently have low progesterone productionand short luteal phases. Treatments using human chorionic gonadotropin (hCG) after FTAI have been tested in aneffort to increase progesterone concentration, improve embryo development and consequently pregnancy rates. Theobjectives of this work were to evaluate the effects of administration of hCG on day 4 after FTAI on induction ofovulation of the first dominant follicle, corpus luteum (CL) development, progesterone production and pregnancyrate in lactating beef cows.Materials, Methods & Results: Five hundred and sixty nine multiparous Angus suckled beef cows, 45-70 dayspostpartum, were synchronized to FTAI. On day -9, intravaginal implants containing 0,750 g of progesterone wereinserted and 2mg of estradiol benzoate administered, im. Seven days later, cows had their implants removed andwere injected with 150 µg of d-cloprostenol, im, and 1 mg of estradiol cipionate, im. Cows were inseminated 52-56h after implant removal. Four days later, cows were assigned into two groups, hCG (1500 UI of hCG, im, n = 269) orControl (1,5 mL saline, im, n = 300). Blood samples were collected on days 4, 7, 10 and 14 after FTAI for analysisof serum progesterone concentration by radioimmunoassay. Ovarian ultrasonographic exams were done on day 0 todetermine the diameter of ovulatory follicle (OF), on day 4 to measure the diameter of the first dominant follicle and,on day 7, to determine the CL area (cm2) and the number of accesory CL. Pregnancy diagnosis were done on day 30.Pregnancy rates were compared by chi-square test, progesterone concentration and CLs parameters were comparedby student-t test. The administration of hCG resulted in higher serum progesterone concentration, improved CL areaand the frequency of accessory CL...(AU)

Resposta reprodutiva de novilhas de corte associada a marcadores moleculares relacionados à fertilidade / Reproductive Performance of Beef Cattle Heifers Associated with Molecular Markers Related to the Fertility

Background: The marker assisted selection (MAS) is indicated as an auxiliary strategy to increase the productive performance in cattle. The principle consists in the identifi cation and selection of molecular markers associated with genes involved directly or indirectly with the expression of a desired trait, usually multifactorial and polygenic. The pregnancy rate is a form of expression fertility, with great economic importance in cattle production systems. The pregnancy rate is a multifactorial trait, which is infl uence by genetics, environment and their interactions. In the current study was search for an association between the reproductive response, expressed by pregnancy rate at insemination and pregnancy rate at the end of the mating season, and molecular markers of genes related to IGF-1 receptor, LHß, Leptin, receptors of FSH and LH. Materials, Methods & Results: Data were evaluated from 249 beef heifers of British breeds, Angus, Devon and crosses. The animals at fourteen or twenty seven months were subjected to different protocols for artificial insemination (AI) and fixed-time artificial insemination (TAI), followed by clean up bulls. The protocols AI and TAI, called AI/TAI, were: Group 1 -Ovsynch protocol (27th months). At day zero the animals received an injection of a GnRH at a dose of 10 µg buserelin, at seventh day received 500 µg of cloprostenol sodium, at ninth day the animals received another dose of 10 µg of buserelin. TAI was performed 10 h after the application of buserelin; Group 2 - Protocol Crestar® with ½ dose of estradiol valerate injectable (27th months). At eighth day the implant was removed, followed by 375 µg of cloprostenol sodium. At ninth day, was administered 1 mg of estradiol benzoate. TAI was performed in tenth day, 52 h after implant removal; Group 3 - Control group (27th months), with AI 12 h after estrus during the fi rst seven days. Seventh day, was applied 375 µg of cloprostenol sodium on all heifers not inseminated, followed by AI for fi ve days more; Group 4 (14th months) - Same protocol of the Group 2; Group 5 (14th months) - Same protocol of the Group 3. During the group formation, blood samples for extraction of DNA were obtained individually from all experimental animals. Microsatellite markers (short tandem repeats, STR) and/or single nucleotide polymorphisms (SNPs) were investigated by means of polymerase chain reaction (PCR). The STR investigated were the AFZ-1, HEL5, ILST002, IDVGA51, FSHR and LHR. We considered the effects of the treatment groups, age, body condition score (BCS), reproductive tract score (RTS), weight at the beginning of the breeding season, daily weight gain on pregnancy rate to AI/TAI and pregnancy rate to final. Molecular markers investigated did not show association with pregnancy rate. The mean pregnancy rate at insemination was 41.0% and the pregnancy rate final was 91.6%. There were no differences in pregnancy between the age of the animals. The average weight at the beginning of the mating was 313 kg without differentiate between animal that become pregnant or empty during the reproductive season. The RTS influenced the pregnancy rate after insemination in respectively 0%, 32.1% and 49.5% (P < 0.05) for RTS 1, 2 and 3. Discussion: Molecular markers AFZ-1, HEL5, ILST002, IDVGA51, FSHR and LHR could not be associated with pregnancy rate at insemination and pregnancy in beef heifers, perhaps because the high degree of reproductive selection that these animals are subjected. The nutritional status of the herd, expressed by weight and body condition score at mating of animals contributed to the achievement of significant pregnancy rates. The reproductive tract score can be considered as a predictor of fertility in herds of beef heifers.

Avaliação do desempenho reprodutivo de vacas de corte lactantes submetidas à IATF a partir da aplicação do GnRH, da manifestação estral, da reutilização de dispositivos intravaginais e da condição corporal / Evaluation of reproductive performance of lactating beef cows subjected to FTAI from the application of Gnrh, estrus manifestation, re-use of intravaginal devices and body condition

Background: The success of fixed-time artificial insemination (FTAI) is linked to several factors that affect pregnancy rates. The use of different hormones, estrus expression and body condition score (BCS) are variables that can influence the results of the technique. The increased production of calves provides greater amount of steers to slaughter. The productive intensification of the beef cows breeding depends on factors related to reproductive technique used and the physiological conditioning of animals. The objective of this study was to evaluate the effect of the application of GnRH, estrus manifestation, re-use of progesterone intravaginal devices and BCS on pregnancy rates of cows subjected to FTAI. Materials, Methods & Results: Were analyzed the effects of GnRH injection and re-use of intravaginal device, estrus manifestation and body condition score (BCS) on reproductive performance of 222 Montana beef cows subjected to fixedtime artificial insemination (FTAI). The FTAI protocol was based on the placement of intravaginal progesterone device (1st, 2nd or 3rd use) and application of estradiol benzoate (E.B.) (2 mg) on day 0. On day 8 was applied sodium cloprostenol (500 µg), removed the intravaginal device and performed the separation of calves. On day 9 was applied E.B. (1 mg) and started the observation of estrus in the morning, afternoon and morning of day 10. On the afternoon of day 10 was realized the insemination, part of the animals showed estrus received buserelin acetate (GnRH) (100µg); the same was proceeded with the animals without estrus. After FTAI the calves returned to cows. Thus, it was formed four groups: Without-Estrus/Without-GnRH; Without-Estrus/With-GnRH; With-Estrus/Without-GnRH; With-Estrus/With-GnRH. The evaluation alone of application of GnRH (with and without) and estrus manifestation (with and without) had no effect on pregnancy rates to FTAI and pregnancy final (P > 0.05). The evaluation of the interaction between GnRH and estrus had no effect on the FTAI pregnancy (P > 0.05): cows Without-Estrus/Without-GnRH did not differ those with GnRH, 33.3% and 48.4% respectively; cows With-Estrus/Without-GnRH did not differ those with GnRH, 53.2% and 53.8% respectively. Intravaginal device 1st, 2nd and 3rd use did not influence pregnancy rates to FTAI and final pregnancy, 50.0%, 57.7%, 41.7% and 91.7%, 88.5%, 93 8% respectively (P > 0.05). The BCS influenced the pregnancy rate to FTAI and final pregnancy, animals with BCS ≥ 3.0 had a higher pregnancy rate to FTAI and animals with BCS ≥ 2.5 had a higher pregnancy to final pregnancy (P < 0.05). The BCS also influenced the estrus manifestation, animals with BCS ≥ 2.5 had higher rates of estrus (P < 0.05). The intravaginal device 1st use promoted greater estrus manifestation in relation to the 2nd and 3rd use (P < 0.05). Discussion: The pregnancy rates did not have the effect of application of GnRH. Some studies report that effect of GnRH is related to estrus phase of the cow. Although 11 percentage points above to cows with estrus, the manifestation estrus did not influence the pregnancy and also did not interact with GnRH. However, it is reported that estrus before at insemination may be conducive to conception. The intravaginal devices used did not influence the pregnancy rates, showing that it is possible re-use them. The results showed at importance of BCS to pregnancy, studies report that cows with low BCS have difficulty to pregnant at FTAI and clean-up bulls. The estrus manifestation was influenced by the BCS and the intravaginal device used.

Efeitos do uso de GNRH no momento da IATF e dias pós-parto sobre a taxa de prenhez em vacas de corte com cria ao pé / Effects of the use of GnRH in the moment of fixed-time artificial insemination and postpartum days on the pregnancy of the nursing beef cows

A falha na detecção de estros e o anestro pós-parto são as principais causas da baixa fertilidade nos rebanhos bovinos. Para minimizar estes problemas uma das biotecnologias recomendadas é o emprego da Inseminação Artificial em Tempo Fixo (IATF). O trabalho avaliou o uso de GnRH no momento da IATF e o número de Dias Pós-Parto (DPP) sobre o desempenho reprodutivo. Foram utilizadas 32 vacas de corte com cria ao pé, 15 vacas formaram o grupo GnRH e 17 o grupo controle. As vacas estavam com data média de 74 DPP por ocasião da IATF.Os animais formavam um grupo homogêneo sendo manejados em iguais condições.As vacas receberam no dia “0” 2 mg de benzoato de estradiol e implante intravaginal de progesterona usado previamente (2º uso), no 6º dia foi aplicado 0,375 mg de Cloprostenol Sódico e no 8º dia, pela manhã, foram retirados os implantes, separados os bezerros e foi aplicado 0,5 mg de cipionato de estradiol. No dia 10º dia pela tarde procedeu-se a IATF. Neste momento, aleatoriamente, de cada duas vacas uma recebia 100μg de análogo sintético ao GnRH. Sete dias após a IATF os animais

The lack of estrous detection and the postpartum anestrous are the largest causes of the low fertility in the beef cattle herds. To minimize these problems one of the recommended biotechnology it is the use of the fixed-time artificial insemination (TAI). This work evaluated the use of GnRH at the moment of TAI and the postpartum days (PPD) on the reproductive performance. Data of the thirty two cows rearing calves were used. Fifty cows formed the group GnRH and 17 the group control. The PPD of the cows were in medium 74 days for occasion of TAI. The animals formed one homogeneous group being handled equally. All cows received in the day “0” 2 mg of estradiol benzoato and one intravaginal implant content progesterone of 2nd use. On the 6th day was applied 0,375 mg of sodic cloprostenol and in the 8th day, by the morning, the implants were take off and the calves were separated temporarily and were applied 0,5 mg of estradiol cipionate. On the 10th day at the afternoon TAI was done. At this time randomly, one of each two cows received 100 µg of synthetic analogue to GnRH. Seven days after TAI the animals were allocated into one field with more 35 cows and 2 clean-up bulls during 60 days. It was evaluated the effects on the GnRH application on the Pregnancy rate at TAI (PRTAI) and the pregnancy rate after clean-up bulls (PRB). The effects of the PPD were analyzed on the PRTAI and PRB. The PRTAI was of 46.7% and 35.3%, respectively for the cows of the groups GnRH and control (P>0.05). The PRB was of 53.3% and 64.7%, respectively for the cows of the group GnRH and control (P>0.05). There was not relationship by the use of GnRH with PRTAI and PRB. For analyze the PPD it was formed two groups. One group (14 cows) with average of 57 ± 18.4 PPD (PPD57) and other group (18 cows) with average of 88 ± 9.1 PPD (PPD88). In the groups PPD57 and PPD88 the PRTAI was respectively 42.9% and 38.9% (P>0.05); and the PRB was respectively 64.3% and 55.6% (P>0,05)

Efeitos do uso de GNRH no momento da IATF e dias pós-parto sobre a taxa de prenhez em vacas de corte com cria ao pé / Effects of the use of GnRH in the moment of fixed-time artificial insemination and postpartum days on the pregnancy of the nursing beef cows

A falha na detecção de estros e o anestro pós-parto são as principais causas da baixa fertilidade nos rebanhos bovinos. Para minimizar estes problemas uma das biotecnologias recomendadas é o emprego da Inseminação Artificial em Tempo Fixo (IATF). O trabalho avaliou o uso de GnRH no momento da IATF e o número de Dias Pós-Parto (DPP) sobre o desempenho reprodutivo. Foram utilizadas 32 vacas de corte com cria ao pé, 15 vacas formaram o grupo GnRH e 17 o grupo controle. As vacas estavam com data média de 74 DPP por ocasião da IATF.Os animais formavam um grupo homogêneo sendo manejados em iguais condições.As vacas receberam no dia “0” 2 mg de benzoato de estradiol e implante intravaginal de progesterona usado previamente (2º uso), no 6º dia foi aplicado 0,375 mg de Cloprostenol Sódico e no 8º dia, pela manhã, foram retirados os implantes, separados os bezerros e foi aplicado 0,5 mg de cipionato de estradiol. No dia 10º dia pela tarde procedeu-se a IATF. Neste momento, aleatoriamente, de cada duas vacas uma recebia 100μg de análogo sintético ao GnRH. Sete dias após a IATF os animais(AU)

The lack of estrous detection and the postpartum anestrous are the largest causes of the low fertility in the beef cattle herds. To minimize these problems one of the recommended biotechnology it is the use of the fixed-time artificial insemination (TAI). This work evaluated the use of GnRH at the moment of TAI and the postpartum days (PPD) on the reproductive performance. Data of the thirty two cows rearing calves were used. Fifty cows formed the group GnRH and 17 the group control. The PPD of the cows were in medium 74 days for occasion of TAI. The animals formed one homogeneous group being handled equally. All cows received in the day “0” 2 mg of estradiol benzoato and one intravaginal implant content progesterone of 2nd use. On the 6th day was applied 0,375 mg of sodic cloprostenol and in the 8th day, by the morning, the implants were take off and the calves were separated temporarily and were applied 0,5 mg of estradiol cipionate. On the 10th day at the afternoon TAI was done. At this time randomly, one of each two cows received 100 µg of synthetic analogue to GnRH. Seven days after TAI the animals were allocated into one field with more 35 cows and 2 clean-up bulls during 60 days. It was evaluated the effects on the GnRH application on the Pregnancy rate at TAI (PRTAI) and the pregnancy rate after clean-up bulls (PRB). The effects of the PPD were analyzed on the PRTAI and PRB. The PRTAI was of 46.7% and 35.3%, respectively for the cows of the groups GnRH and control (P>0.05). The PRB was of 53.3% and 64.7%, respectively for the cows of the group GnRH and control (P>0.05). There was not relationship by the use of GnRH with PRTAI and PRB. For analyze the PPD it was formed two groups. One group (14 cows) with average of 57 ± 18.4 PPD (PPD57) and other group (18 cows) with average of 88 ± 9.1 PPD (PPD88). In the groups PPD57 and PPD88 the PRTAI was respectively 42.9% and 38.9% (P>0.05); and the PRB was respectively 64.3% and 55.6% (P>0,05)(AU)

Efeitos do número de dias pós-parto sobre o desempenho bioeconômico de vacas de corte submetidas à inseminação artificiall em tempo fixo (IATF) / Bioeconomic performance of beef cows submitted to a fi xed time insemination program in different periods after calving

Sessenta vacas foram divididas em dois grupos (Grupo I, n=35; Grupo II, n=25), conforme os dias pós-parto por ocasião da inseminação artificial em tempo fixo (IATF), realizada em 07/12/2007. Os animais do Grupo I, por ocasião da IATF, apresentaram um número de dias pós-parto (DPP) médio de 89,4 dias, enquanto os animais do Grupo II apresentaram um DPP médio de 65,1 dias (p0,05)...

Sixty cows were divided in two groups (Group I, n=35; Group II, n=25), this division was realized in 07/12/2007 according to the postpartum days for occasion of artifi cial insemination (FTAI) in all animals. The average number of postpartum days was 89.4 in the Group I and in the Group II the average number was 65.1 days (p0,05). However, the pregnancy cost at FTAI was for Group I and Group II, respectively, R$ 83,30 and R$ 148,75. PR-Final resulted in a final cost/ pregnancy of R$ 75,22 and R$ 81,87, respectively for Groups I and II. The cows submitted to the FTAI in different periods postpartum presented different cost/ pregnancy. The variable cost/pregnancy is directly related to the pregnancy rate to the FTAI as well as after the use of clean-up bulls

Efeitos do número de dias pós-parto sobre o desempenho bioeconômico de vacas de corte submetidas à inseminação artificiall em tempo fixo (IATF) / Bioeconomic performance of beef cows submitted to a fi xed time insemination program in different periods after calving

Sessenta vacas foram divididas em dois grupos (Grupo I, n=35; Grupo II, n=25), conforme os dias pós-parto por ocasião da inseminação artificial em tempo fixo (IATF), realizada em 07/12/2007. Os animais do Grupo I, por ocasião da IATF, apresentaram um número de dias pós-parto (DPP) médio de 89,4 dias, enquanto os animais do Grupo II apresentaram um DPP médio de 65,1 dias (p<0,01). Os animais de ambos grupos foram submetidos a um protocolo que combinou a utilização de progesterona, benzoato de estradiol (B.E) e prostaglandinaF2alfa (PGF2alfa). Todos os animais foram inseminados 30 horas+/- 2h após a aplicação da segunda dose de B.E. Cinco dias após a inseminação os animais foram submetidos ao repasse com utilização de 3,33% de touros aptos à reprodução por mais 76 dias. O diagnóstico de gestação foi realizado por palpação retal após 40 dias da inseminação artificial e após 60 dias da retirada dos touros. Foi analisado o escore de condição corporal por ocasião da inseminação artificial (ECC-IA), o escore de condição corporal por ocasião do diagnóstico de gestação (ECC-DG), a taxa de prenhez à inseminação artificial (TP-IA) e a taxa de prenhez após o repasse com touros (TP-Final). Na análise econômica, os parâmetros utilizados foram: custo/vaca inseminada (R$), custo final/vaca (R$), custo/prenhez à IATF (R$) e custo/prenhez final (R$). Os resultados não indicaram diferenças estatísticas para o ECC e taxas de prenhez entre os grupos, sendo as TP-IA e TP-Final de 42,9% e 91,4% e de 24,0% e 84,0%, respectivamente para os grupos I e II (IATF para Grupo I e Grupo II foi, respectivamente, R$ 83,30 e R$ 148,75. A TP-Final re-sultou em um custo/prenhez de R$ 75,22 e R$ 81,87, respectivamente para os grupos I e II. Vacas submetidas à IATF em diferentes períodos pós-parto apresentaram diferentes custo/ prenhez. A variável custo/prenhez está diretamente relacionada com a taxa de prenhez tanto à IATF quanto após o repasse com touros. p>0,05)...(AU)

Sixty cows were divided in two groups (Group I, n=35; Group II, n=25), this division was realized in 07/12/2007 according to the postpartum days for occasion of artifi cial insemination (FTAI) in all animals. The average number of postpartum days was 89.4 in the Group I and in the Group II the average number was 65.1 days (p<0,01). The cows from the two groups were submitted to one protocol using progesterone, prostaglandin F2alfa (PGF2a) and estradiol benzo¬ate. The cows were inseminated already 30 hours +/- 2h after the application of the second dose of estradiol benzoate. Five days after the insemination the animals were submitted to clean-up bulls (3,33%) able to reproduction for more than 76 days. The pregnancy diagnosis was realized by rectal palpation after 40 days of artificial insemination and after 60 days of withdrawal of bulls. The variables analyzed were: The body condition score for occasion of artifi cial insemination (BCS-AI), the body condition score for occasion of pregnancy diagnosis (BCS-GD), the preg¬nancy rate after the end of the mating season (PR-Final) with bulls. For the economic analysis the parameters used were: cost/inseminated cow (R$), final cost/cow (R$), pregnancy cost at FTAI (R$) and final cost/ pregnancy (R$). The results of experiment did not indicate statistical differences for BCS and pregnancy rates between the groups. The results of PR-AI and PR-Final were: 42.9%, 91.4% and 24.0%, 84.0%, respectively for groups I and II (p>0,05). However, the pregnancy cost at FTAI was for Group I and Group II, respectively, R$ 83,30 and R$ 148,75. PR-Final resulted in a final cost/ pregnancy of R$ 75,22 and R$ 81,87, respectively for Groups I and II. The cows submitted to the FTAI in different periods postpartum presented different cost/ pregnancy. The variable cost/pregnancy is directly related to the pregnancy rate to the FTAI as well as after the use of clean-up bulls(AU)