Two trials were conducted to study the effect of feeding a protected-fat supplement on reproduction. In the first trial eight ovariectomized brangus cows were used to study the effect of feeding a protected-fat supplement on LH release after GnRH injection. The cows were equally divided at random into two groups (control and treatment), placed in individual pens, and fed a ration supplying 4.0 kg of TDN per head daily. Cows in the treatment group received a .68 kg of protected fat daily for the entire experimental period (30 days). On the last day of the experiment an indwelling jugular catheter was inserted into the cows and blood samples were taken every ten minutes for a period of 5 hours. After the sixth sample was taken, 200 (mu)g of GnRH were injected intramuscularly to induce LH release. The samples taken before the GnRH was injected were used to establish basal LH levels. LH levels were analyzed by using the double antibody radioimmunoassay technique. Average weight of the cows at the start of the trial for the control and treatment group were 491 and 457 kg respectively. Cows in the control group lost weight (-8 kg) during the experimental period, whereas those in the treatment group gained 33 kg. The highest LH peak value was 12 ng/ml for the controls and 43 ng/ml for the treated cows. Mean LH values were 4.9 ng/ml for the control group and 43 ng/ml for the treatment group. In the second experiment twenty multiparous four-year-old pregnant brangus cows are used to determine the effect of a protected fat diet on postpartum pituitary response to GnRH. As cows calved they were randomly assigned to either the control or treatment group. The treatment consisted of adding .68 kg of protected fat to the ration. The diet for both groups was designed to supply approximately 4.4 kg of TDN daily per animal. This was about 80% of the NRC requirement. On day 7 postpartum an indwelling catheter was inserted into the jugular vein. Blood samples were taken for 5 hours every ten minutes. After the sixth sample was taken 200 (mu)g of GnRH were injected intramuscularly to induce LH release. The pre-GnRH injection period was used to establish basal LH levels. Luteinizing hormone levels were analyzed using the radioimmunoassay double antibody technique. The latter part of this experiment was designed to assess the effect of a protected fat diet on postpartum estrus activity. Estrus was also checked by daily visual observation. Average weight of the cows at the start of the experiment was 514 and 474 kg for the control and the treatment group respectively. By the end of the trial (75th day) cows in the control group lost 35 kg, and those in the treatment group lost 22 kg. Average daily gain of calves whose mothers were on treatment or control did not differ. Mean LH levels were 18 and 13 ng/ml for the treatment and control cows respectively. This difference was not statistically significant due to a large mean standard error. Fifty percent of the cows receiving the protected fat supplement had shown standing estrus by day 45 postpartum vs 20% for the control group. By day 15 pospartum 60% of the cows in the treatment group had shown signs of postpartum estrus activity vs only 10% for the control group. By day 45 postpartum all the cows receiving the protected fat supplement had shown signs of estrus activity vs only 50% for the control.

No description available.

Factors affecting bovine ovarian responsiveness to stimulation by pregnant mare's serum gonadotropin (PMSG) were studied. Initially, the effects of plasma progesterone concentration on the response were considered using a progesterone-releasing intravaginal device (PRID) to provide an artificial source of the hormone. Due to inherent biological variation in vivo, in vitro methods were developed in which cAMP and progesterone production by granulosa cells were measured. Regardless of the size of the follicles from which the cells originated, PMSG stimulated significant cAMP accumulation. Cyclic AMP production was similar between aspirated granulosa cells and those scraped from the follicle wall, between ovaries with and without a corpus luteum from the same animal, and between follicles from animals early ( 10 days) in their estrous cycles. The PMSG failed to stimulate bovine granulosa cells to synthesize significantly more progesterone than untreated cells. Unlike porcine granulosa cells, bovine cells from antral follicles of any size appeared to luteinize spontaneously in culture. / Hormonal changes in the preovulatory follicle were measured using the PMSG/hCG-treated prepubertal gilt as a model. After hCG administration, follicular fluid levels of cAMP peaked at 4 hr followed 24 hr later by a rise in prostaglandins F and E (PGF, PGE) concentrations which peaked near the expected time of ovulation. Indomethacin injection blocked ovulation and the prostaglandin rise, although the inhibition could be reversed by the administration of PGF(,2)(alpha). Temporal changes in estrone, estradiol-17(beta), progesterone, androstenedione, testosterone and 5 (alpha)-dihydrotestosterone were also measured. / In an effort to decrease endogenous levels of inhibin, thereby increasing endogenous FSH and thence follicular development, heifers, ewes and does were actively immunized against porcine follicular fluid or proteinaceous fractions of bovine seminal plasma. In some animals, plasma FSH concentrations were elevated although ovulation rates and estrous cycle lengths were not altered. / A culdoscopy technique was developed for repeated monitoring of ovarian morphological changes in cows.

Five experiments were undertaken to identify metabolites and hormones that could mediate the effect of dietary energy status on reproduction, particularly pulsatile secretion of luteinizing hormone (LH) postpartum dairy cows. / In the first two experiments, the concentration of progesterone (P4) in tailhead adipose tissue and plasma in 12 cows at different stages of pregnancy and lactation was determined as was P4 produced in vitro by explants of tailhead adipose tissue. Concentration of P4 in adipose tissue was correlated with that of plasma P4 near estrus and during the luteal phase of the estrous cycle, and P4 was released in vitro by fat mobilization. / In the third and fourth experiments, blood was collected continuously for 16 h from four ovariectomized cows offered maintenance or restricted energy diets after priming with P4 or estradiol (E2) using a crossover experimental design. The results indicated that P4 released during body fat mobilization is minor and is not related to LH secretion. Dietary energy restriction influenced plasma LH concentration and pulse amplitude but the effect was modulated by P4 and E2 priming. Dietary energy restriction decreased glucose concentration but did not influence plasma non-esterified fatty acids (NEFA), cortisol, P4 and insulin levels. Cortisol was negatively related to LH pulse frequency. Glucose and insulin were positively and negatively correlated with LH pulse amplitude, respectively. Cortisol, NEFA and glucose jointly had a negative correlation with LH concentration. / In the fifth experiment, blood samples were collected daily for 60 d and every 10 min for 8 h on 18, 36 and 54 d postpartum from 24 cows (12 ovariectomized) fed low (1.4 Mcal/kg DM) (L) or high (1.7 Mcal/kg DM) (H) energy in a 2 x 2 factorial treatment design. LH pulse frequency was reduced at 18 d postpartum in ovariectomized cows, but not in intact cows, fed L. First postpartum ovulation occurred later in intact cows fed L compared to those fed H. Energy balance and plasma glucose concentration were lower, but plasma NEFA, $ beta$-hydroxybutyrate (BHB) and E2 concentrations higher, in cows fed L compared to those fed H. E2 concentration in intact cows fed L was elevated for a prolonged period prior to first ovulation. Diet had no influence on plasma P4 and insulin concentrations. Plasma E2 and BHB concentrations were positively correlated with LH pulse frequency in intact cows across diets and ovariectomized cows fed L, respectively. NEFA were negatively correlated with LH pulse amplitude in ovariectomized cows fed L. Glucose, NEFA and P4 were negatively, but BHB, E2 and insulin positively correlated, individually or in association, with LH concentration. / Overall, the results suggest that the effect of dietary energy status on LH patterns and timing of onset of postpartum ovulation is modulated by priming with or presence of ovarian steroids. The relationships of metabolites and hormones with LH patterns appear to change with dietary energy level, ovarian status and mutual associations among the metabolites and hormones. These parameters, especially glucose and BHB, may be potential mediators of the effect of dietary energy status on LH patterns. (Abstract shortened by UMI.)

No description available.

Made available in DSpace on 2014-08-13T14:50:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-07-29Bitstream added on 2014-08-13T18:00:52Z : No. of bitstreams: 1 000753005.pdf: 2398846 bytes, checksum: 88a9bdc09aaab4eb0166b0e572c83bb7 (MD5) / As alterações no microambiente do trato reprodutivo comprometem a competência oocitária e o desenvolvimento embrionário pré-implantacional em bovinos. Vacas Bos indicus apresentam adaptações fenotípicas e genotípicas conferindo maior resistência e tolerância à temperatura elevada quando comparadas as vacas Bos taurus, que sofrem redução nos índices de prenhez durante os meses quentes do ano. Esta infertilidade causada pelo estresse térmico é um problema de ordem multifatorial, entretanto já foi demonstrado que o oócito e embrião são extremamente susceptíveis aos efeitos deletérios da temperatura elevada. Os danos celulares desencadeados pela temperatura elevada podem ser manipulados pelo fator de crescimento semelhante à insulina-I (IGF-I), que além de minimizar a morte celular espontânea, resgata células que já iniciaram apoptose induzida por diferentes agentes ou estresses. A primeira etapa deste projeto visou avaliar o efeito dose resposta do IGF-I durante a maturação in vitro (MIV) em meio quimicamente não definido (pré-experimento 1: meio MIV - 10% de soro fetal bovino) e semidefinido (pré-experimento 2: meio MIV - 6 mg/mL de albumina sérica bovina) na competência de desenvolvimento de oócitos bovinos. Para tanto, complexos cumulus-oócito (CCOs) de vacas (mestiças Bos indicus) oriundas de abatedouro foram maturados in vitro em meio MIV não definido ou semidefinido suplementado com 0 (controle veículo), 6,25; 12,5; 25; 50; 100 ou 200 ng/mL de IGF-I por 22-24 h. Em seguida os oócitos foram fecundados (FIV) e cultivados in vitro (CIV). A adição de 25 ng/mL de IGF-I no meio MIV semidefinido ou não definido aumentou a porcentagem de oócitos clivados no dia 3 e a taxa de blastocisto no dia 8 após a fecundação. Dessa forma, a dose de 25 ng/mL de IGF-I foi utilizada na segunda etapa deste projeto, cujo objetivo foi avaliar o papel do IGF-I na competência de desenvolvimento de ... / Microenvironmental alterations on reproductive tract compromise oocyte competence and pre-implicational embryo development in bovine. This fact is well characterized in animals exposed to heat stress. Bos indicus have fenotypic and genotypic adaptations which confers a higher tolerance to high temperatures compared with Bos taurus, suffering a reduction in the pregnancy rates during the hot months. This infertility caused by heat stress is a multifactorial problem, however it has been shown that oocyte and embryo are very susceptible to deleterious effects of high temperature. The cellular damage induced by high temperature could be manipulated by insulin-like growth factor I (IGF-I), which besides minimizing the spontaneous cell death, IGF-I rescue cells which have already initiated the apoptosis induced by different agents or stresses. The first step of this project aimed to evaluate dose-response effect of IGF-I during the maturation in vitro (MIV) in a non-defined medium (pre-experiment 1: MIV - 10% of bovine fetal serum) and semi-defined (preexperiment 2: MIV - 6 mg/mL of bovine albumin serum) in competence of bovine oocytes. Therefore, cumulus-oocyte complexes (CCOs) obtained of cows (Bos indicus crossbreed) from a slaughterhouse were matured in vitro in non-defined and semidefined MIV medium supplemented with 0 (vehicle control), 6,25; 12,5; 25; 50; 100 or 200 ng/mL of IGF-I for 22-24 h. After, oocytes were fertilized (FIV) and cultured in vitro (CIV). The adition of 25 ng/ml of IGF-I on non-defined and semi-defined MIV medium increased porcentage of cleavage on day 3 and blastocysts rate in day 8 after fertilization. In this way, 25 ng/ml IGF-I was used on second step of this experiment, which objective was to evaluate the role of IGF-I on oocyte competence of oocytes collected from Bos indicus – Nelore (NEL; n= 6) and Bos taurus-Holstein (HPB; n= 6) exposed to heat stress. Therefore, cows adapted ...

Made available in DSpace on 2014-06-11T19:25:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-05-02Bitstream added on 2014-06-13T19:12:07Z : No. of bitstreams: 1 pinto_rfp_me_botib.pdf: 235047 bytes, checksum: f66f9dd3e29764cee35ce259fd850b2c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O fator de crescimento fibroblástico (FGF10) atua de forma parácrina no complexo cumulus-oócito, aumentando a expressão de genes relacionados à expansão das células do cumulus e à competência oócitária. Objetivou-se com o presente estudo testar se a adição do FGF10 ao meio de maturação melhora a maturação, diminui as taxas de oócitos apoptóticos e influencia na produção de embriões in vitro e na expressão de genes relacionados à competência e implantação embrionárias (COX2, CDX2 e PLAC8). Em todos os experimentos, oócitos foram obtidos de abatedouro, coletados de vacas adultas e maturados por 22 h em meio TCM 199 suplementado com: 2.5 ng/mL FGF10, 10 ng/mL FGF10, 50 ng/mL FGF10 ou na ausência de FGF10 (grupo controle). No Experimento 1, depois da maturação, os oócitos foram fixados e corados com TUNEL para determinar a porcentagem de oócitos apoptóticos e posteriormente com Hoechst-33342 para avaliação dos diferentes estágios da meiose (metáfase 1, metáfase 2 ou metáfase 2 com extrusão do primeiro corpúsculo polar). No Experimento 2, os oócitos foram fertilizados e cultivados até o estágio de blastocisto inicial. No experimento 3 avaliou-se o efeito da suplementação do FGF10 ao meio de maturação in vitro sobre a expressão dos genes COX2, CDX2 e PLAC8 em embriões bovinos. No experimento 1, os resultados demonstraram que a dose de 2,5 ng/mL FGF10 aumentou a porcentagem de oócitos com extrusão do primeiro corpúsculo polar (36%) quando comparado as doses de 10 ng/mL FGF10 (13%), 50 ng/mL FGF10 (12%) e grupo controle (19%; p≤0.05). Com relação ao número de oócitos apoptóticos, as maiores doses de FGF10 apresentaram menor quantidade de oócitos TUNEL-positivos (10 ng/mL and 50 ng/mL FGF10, 5% e 6%, respectivamente) quando comparados a menor... / Not available

Made available in DSpace on 2014-06-11T19:32:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-17Bitstream added on 2014-06-13T19:21:22Z : No. of bitstreams: 1 machado_mf_dr_botib.pdf: 3725562 bytes, checksum: d4f694ed133c9c007068eeeff7ba0042 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Fatores de crescimento fibroblástico (FGFs) regulam o desenvolvimento folicular e a maturação oocitária através de ligação aos seus receptores (FGFRs). Os RNAm que codificam o FGFR2c e o FGFR3c foram detectados em folículos antrais bovinos. Com o objetivo de identificar FGFs que poderiam regular a foliculogênese por meios desses, investigou-se os padrões de expressão do FGF16 e FGF20 em folículos antrais bovinos, bem como os níveis de RNAm desses FGFs e seus receptores (FGFR2c e FGFR3c) durante a maturação in vitro de complexos cumulus-oócito (COCs). Além disso, dados preliminares do nosso laboratório indicativos de que a expressão do FGF17 em oócitos é regulada ao longo da maturação oocitária motivaram a investigação da função dessa proteína na maturação de COCs in vitro. Sendo assim, avaliou-se o efeito do FGF17 na expansão do cumulus e no controle da transcrição de fatores EGF-like [ampiregulina (AREG), epiregulina (EREG) e betacelulina (BTC)] e outros genes reguladores da expansão [cicloxigenase 2 (COX2), hialurona sintase 2 (HAS 2), pentraxina 3 (PTX3), proteína indutora do fator de necrose tumoral 6 (TSG6)]. Os RNAm dos FGF16 e FGF20 e as respectivas proteínas foram detectados no ovário bovino. A abundância de RNAm de FGF16 e FGF20 foi maior em células da granulosa e da teca de folículos atrésicos comparados a folículos saudáveis ou transicionais. O tratamento com FSH diminuiu a abundância de RNAm para FGF16 e FGF20 e o IGF1 inibiu FGF16 em células da granulosa cultivadas in vitro. Ao longo da maturação a expressão do FGF16 e do FGF20 foi estável no oócito, enquanto que a expressão dos receptores FGFR2c e FGFR3c foi estimulada nas células do cumulus pelo FSH. A proteína FGF16 foi localizada no oócito, células do cumulus e da teca e o FGF20 em oócitos, células do cumulus, da granulosa e da teca. O FGF17 aumentou a proporção... / Fibroblast growth factors (FGFs) regulate follicular development and oocyte maturation. Messenger RNA encoding receptors FGFR3c and FGFR2c have been detected in bovine antral follicles. Aiming to identify FGFs that can potentially regulate folliculogenesis through these receptors, the expression patterns of FGF16 and FGF20 were assessed in bovine antral follicles. Messenger RNA expression of these FGFs and their receptors (FGFR2c and FGFR3c) was also assessed in oocytes and cumulus cells, respectively, during in vitro maturation. In addition, previous data suggesting that FGF17 mRNA expression is regulated in the oocyte led us to investigate the effects of FGF17 on cumulus expansion and on the expression of EGF-like factors [amphiregulin (AREG), epiregulin (EREG) and betacelullin (BTC)] and other genes that regulate expansion [cyclooxygenase 2 (COX2), hyaluronan synthase 2 (HAS 2), pentraxin 3 (PTX3), protein-inducing tumor necrosis factor 6 (TSG6)]. FGF16 and FGF20 mRNA and proteins were detected in the bovine ovary. Messenger RNA abundance of FGF16 and FGF20 was higher in granulosa and theca cells from atretic follicles compared with healthy or transitional follicles. Treatment with FSH decreased mRNA expression of FGF16 and FGF20 and IGF1 inhibited FGF16 mRNA abundance in cultured granulosa cells. During maturation, mRNA expression of FGF16 and FGF20 was stable in the oocyte, while FGFR2c and FGFR3c were stimulated in cumulus cells by FSH. FGF16 protein was localized to the oocyte, cumulus and theca cells, and FGF20 was detected in the oocyte, cumulus, granulosa and theca cells. Supplementation of maturation medium with FGF17 increased the proportion of fully expanded COCs, but did not alter mRNA expression of COX2, HAS2, PTX3, TSG6, AREG, EREG and BTC in cumulus cells during in vitro maturation. In conclusion, FGF17 enhances bovine cumulus expansion... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:35:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-12-12Bitstream added on 2014-06-13T20:26:12Z : No. of bitstreams: 1 camargos_as_dr_botfmvz_parcial.pdf: 67933 bytes, checksum: 2094efb1e7f37edf06ccd1d3f8b62930 (MD5) Bitstreams deleted on 2015-02-09T14:35:35Z: camargos_as_dr_botfmvz_parcial.pdf,Bitstream added on 2015-02-09T14:36:19Z : No. of bitstreams: 1 000711994.pdf: 521661 bytes, checksum: 002c33dc96d33e4102653cbd3a53db4d (MD5) Bitstreams deleted on 2015-02-09T17:15:01Z: 000711994.pdf,Bitstream added on 2015-02-09T17:15:38Z : No. of bitstreams: 1 000711994.pdf: 521661 bytes, checksum: 002c33dc96d33e4102653cbd3a53db4d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este estudo foi dividido em três experimentos. No experimento 1, objetivou-se avaliar e comparar o efeito da administração de análogo sintético de prostaglandina em diferentes períodos do puerpério de bubalinos. 45 búfalas pluríparas foram distribuídas aleatoriamente em três grupos: CON (controle) – soro fisiológico na primeira e terceira semanas pós-parto; CLO1 – cloprostenol sódico na primeira semana e; CLO3 – cloprostenol sódico na terceira semana. Os animais foram avaliados nos dias 7, 14, 21, 28 e 35 após o parto quanto ao grau de involução uterina, acúmulo de fluido intrauterino, concentração de progesterona plasmática, período de serviços e intervalo entre partos. Não houve diferença entre os grupos quanto ao grau de involução uterina e concentração de progesterona plasmática. Os animais dos grupos CLO1 e CLO3 apresentaram menor acúmulo de fluido intrauterino, período de serviços e intervalo entre partos em relação ao grupo controle. O protocolo com aplicação de cloprostenol na primeira semana apresentou os melhores resultados sobre a eficiência reprodutiva de búfalas pós-parto. No experimento 2, o objetivo do estudo foi verificar se a aplicação de cloprostenol, no puerpério precoce ou intermediário, induz mudanças nas concentrações plasmáticas de progesterona, PGFM e estradiol de búfalas pós-parto, além de efeitos sobre a involução uterina, acúmulo de fluido intrauterino e retorno da atividade ovariana cíclica. 30 búfalas Murrah foram distribuídas aleatoriamente em três grupos: CONT (solução salina); CLO2 (cloprostenol nos dias 2 e 5 pós-parto) e; CLO15 (cloprostenol nos dias 15 e 20 pós-parto). Exames ginecológicos foram realizados nos dias 2, 7, 14, 21 e 28 pós-parto, onde foram avaliados o grau de involução uterina, o acúmulo de fluido intrauterino e a atividade... / This study was divided into three experiments. In experiment 1, the aim was to evaluate and compare the effect of prostaglandin synthetic analogue administration at different periods of buffalo puerperium. 50 pluriparous buffaloes were randomly divided into three groups: CON (control) – saline at first and third weeks postpartum; CLO1 – chloprostenol at first week and; CLO3 – chloprostenol at third week. Animals were evaluated at days 7, 14, 21, 28 and 35 after parturition about uterine involution degree, uterine fluid accumulation, progesterone plasmatic level, service period and parturition interval. There was no difference between groups on uterine involution degree and progesterone plasmatic level. Groups CLO1 and CLO3 animals presented lower uterine fluid accumulation, service period and parturition interval in relation to control group. The protocol of chloprostenol administration in the first week presented best results on postpartum buffalo reproductive efficiency. In experiment 2, the objective of the study was to verify if chloprostenol administration, at early or intermediary puerperium, can induces changes on progesterone, PGFM and oestradiol plasma concentrations of postpartum buffaloes, beyond effects on uterine involution, intrauterine fluid accumulation and ovarian activity return. 30 Murrah buffaloes were randomly divided into three groups: CONT (saline); CLO2 (chloprostenol at days 2 and 5 postpartum) and; CLO15 (chloprostenol at days 15 and 20 postpartum). Gynecological examinations were performed at days 2, 7, 14, 21 and 28 postpartum, when were evaluated uterine involution degree, intrauterine fluid accumulation and ovarian activity. After exams, were collected blood samples to dosage of progesterone, PGFM and oestradiol plasma concentrations. Group CLO2 showed more uterine involution, faster ovarian activity return and.. (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:35:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-12-02Bitstream added on 2014-06-13T18:46:31Z : No. of bitstreams: 1 calegari_rs_dr_botfmvz.pdf: 6174607 bytes, checksum: b51ee0fe951008c48ebb49f5a60afa88 (MD5) / Universidade Estadual Paulista (UNESP) / Este estudo foi dividido em dois experimentos. No exp. 1, investigou-se a influência do sêmen congelado heterospérmico e homospérmico de touros Nelore sobre o movimento de espermatozóides (ME), integridade da membrana plasmática (IMP) e produção de embriões in vitro (PIV). No exp. 2, a substituição de plasma seminal (PS) de touros com sêmen de média congelabilidade (grupo homospérmico, HoM) por PS heterólogo de touros de alta congelabilidade (grupo homospérmico, HoA), foram avaliados através do ME, IMP, PIV, proteína total (PT), concentração de testosterona plasmática (TP) e padrão eletroforético das proteínas do plasma seminal (PE). O plasma seminal heterólogo (grupo PSH) foi composto pela mistura de PS de touros HoA com espermatozóides de touros HoM. As amostras seminais de oito touros foram classificadas, com base em avaliações anteriores. Para o exp. 1, não foi observada diferença significativa para o ME, IMP e PIV entre os grupos, mas, foi observada entre os touros, independentemente do grupo. No exp. 2, não houve diferença, para o ME, PT, TP e embriões produzidos entre os grupos, entretanto, maior número de membranas plasmáticas intactas (P<0,05) foi encontrado no grupo HoA, bem como para a taxa de clivagem (P<0,05) no grupo PSH. Sete padrões de proteínas (20 a 25 frações) foram detectados no PS. A concentração de PT e TP variou pouco, quando comparada com o PE. Concluindo, o sêmen heterospérmico não melhorou nenhuma característica espermática nem aumentou a produção de embriões in vitro, no entanto, o PSH somente mostrou efeito benéfico sobre a taxa de clivagem. Agradecimentos: Central VR e frigorífico Frig, Araçatuba, SP, Brasil / This study was divided into two experiments. In exp.1, the influence of frozen heterospermic and homospermic bull semen on sperm motion (SM), plasma membrane integrity (PMI) and in vitro embryo production (IVP) were investigated. In exp.2, the replacement of seminal plasma (SP) of bulls with medium semen freezability (homospermic group, MH) by heterologous SP of bulls with high freezability (homospermic group, HH), as evaluated for SM, PMI, IVP, total protein (TP), plasma testosterone level (PT), and electrophoretic profile of plasma seminal protein (EP). The heterologous seminal plasma (HSP) group consisted of a mixture of SP of bull HH with spermatozoa of bull MH. Sperm samples from 8 Nellore bulls were classified based on previous evaluations. In exp. 1, no significant difference was observed for SM, PMI, and IVP among groups, but it was observed among bulls, regardless of group. In exp.2, there was no difference for SM, TP, PT, and yielded embryos among groups, but more intact plasma membranes (P<0.05) were found in group HH as well as for cleavage rate (P<0.05) in group HSP. Seven protein profiles (20 to 25 protein fractions) were detected in SP. Level of TP and PT varied little when compared to the seminal protein profile. In conclusion, heterospermic semen did not improve any sperm characteristic nor enhanced in vitro embryo production, however, HSP only showed beneficial effect on cleavage rate. Acknowledgement: VR Insemination Station and FRIG slaughterhouse, Araçatuba, SP, Brazil