Interaction between protein nutrition and reproductive features in bovine dams

Dietas com excesso de proteína bruta, em especial contendo uréia, têm sido associadas a menores taxas de prenhez, alterações hormonais e diminuição na qualidade de embriões de fêmeas bovinas. A condição de exposição desses animais à uréia por exemplo, dose diária, tipo de dieta, estádio fisiológico) parece ser fator decisivo para manifestação dessas respostas. O mecanismo pelo qual a uréia agiria ainda não foi completamente elucidado, mas algumas hipóteses aventadas são ação sobre oócitos e embriões durante as primeiras clivagens e modificações em ambiente uterino. Entretanto, o uso de uréia em alguns estudos mostrou-se inócuo ao desempenho reprodutivo de fêmeas bovinasDiets containing excessive amounts of crude protein, mainly from urea, have been associated to lower pregnancy rates, shifts in hormonal patterns and poor embryo quality in bovine female. Exposure conditions to urea (e.g., daily dose, type of diet, physiologic status) may be decisive to manifestation of these responses. Mechanism by which urea may act has not been elucidated yet, although some hypotheses are action on oocyte and early embryo and changing in the uterine milieu. Nevertheless, in some studies urea feeding has been shown being harmless to reproduction performance of bovine damn

Heat shock response in PBMCs of Nellore cows after in vitro thermal stress

Abstract Adaptation is an important feature to be studied in animals when thinking about maintenance and raise of productivity. Although Nellore breed is widely disseminated in Brazil, the knowledge related to its thermotolerance in tropical climate conditions remains unknown. Hence, the aim of this study was to understand the Nellore breed cellular adaptation when exposed to heat shock in vitro, using peripheral blood mononuclear cells (PBMCs). The comprehension of the most expressed and sensible heat shock proteins in Bos taurus indicus may elucidate a molecular marker for genetic improvement related to thermotolerance. Previous to blood sampling, the physiological parameters of 16 cows were measured in order to classify them in efficient and non-efficient on heat loss. For this experiment, the blood was collected in three different heparin tubes by jugular venipuncture only in 10 cows, 5 efficient and 5 nonefficient, at morning. The molecular analyzes were performed in Physiology and Molecular Endocrinology Laboratory, Faculty of Veterinary Medicine and Animal Science, University of São Paulo. After sampling, each blood tube were placed in three different water bath devices calibrated for: 38°C, 40°C and 42°C for two consecutive hours. The PBMCs were separated, washed with hemolysis solution, the RNA extracted, the cDNA synthetized and performed the qPCR for the genes HSP60, HSP70 and HSP90. There was a maintenance on HSPs transcripts on 38°C and 40°C and a decrease on all HSPs transcripts at 42°C. Among all, the HSP70 was the most expressed at 38°C and 40°C, elucidating its protective importance. No difference was observed between gene expression and heat loss efficiency. In conclusion, the Nellore cell adaptability was confirmed by the maintenance of heat shock proteins 60, 70 and 90 kDa. The pathway for understanding responses involving thermotolerance is still long and requires more knowledge of cell signaling, either in vitro or in vivo conditions. Taken together, these informations may contribute in future keys for genetic selection of adapted animals

Manipulation of ovarian and uterine function to increase conception rates in cattle

In cattle, embryonic and fetal losses are the major causes of reproductive failure. Losses associated with failure in the process of maternal recognition of pregnancy can amount to as much as 30%. Successful estabblishment of pregnancy depends on a delicate balance between luteolytic mechanisms inherent to the endometrium at the end of diestrus and antiluteolytic mechanisms, orchestrated by the conceptus to change endometrial function and ultimately, block luteolysis. Antiluteolytic strategies are pharmacological, mechanical, nutritional and management manipulations of the process of maternal recognition of pregnancy that aim to increase the probability of succssful gestations. Objective of the present paper is to review the recent literature on antiluteolytic strategies in cattle. Specifically, we focused on strategies to simulate production of progesterone, strategies to reduce production of estradiol and other strategies. Future directions for research in this area are propose

Growth factors and steroidogenesis in the bovine placenta

The control of placental hormone biosynthesis is critical during gestation, since their coordinated action is essential for the normal progress of pregnancy. Hormonal synthesis regulation in placenta is still not elucidated and differs from that observed in other steroidogenic tissues since specific tropic hormones have not yet been identified. Cellular localization of growth factors in the placenta, including VEGF, EGVEGF and bFGF, points that these factors have additional roles in the organ besides their well known modulation on cell proliferation and angiogenesis. In vitro experiments bring new evidence that growth factors play regulatory roles modulating processes related to steroid hormone secretion in the placenta. Importance of local estrogen function has been highlighted and a key enzyme for its synthesis is aromatase cytochrome P450. The objective of this review was to describe some aspects of placental steroidogenesis, mainly focusing on aromatase cytochrome P450 steroidogenic enzyme expression and growth factors as others potential modulators of hormonal synthesis in the orga

Service, conception and pregnancy rates of nelore cows treated with human corionic gonadotropin and estradiol-17'beta' after timed artificial insemination

Avaliaram-se estratégias para reduzir a mortalidade embrionária em bovinos. Vacas Nelore (Bos taurus indicus) foram inseminadas em tempo fixo (IATF - 'D IND. 0') após o protocolo GnRH/'PGF2 IND. a'/GnRH e divididas nos grupos: Controle (Gc; n=55), hCG ('G IND. hCG'; n=55) recebeu 3000 UI da hCG no 'D IND. 5' , 'E IND. 2' ('G IND. E2'; n=55) recebeu 5 mg de '17 IND. b'- Estradiol ('E IND. 2') no 'D IND. 12' e hCG/'E IND. 2' ('G IND. hCG/E2'; n=55) recebeu 3000 UI da hCG no 'D IND. 5' e 5mg do 'E IND. 2' no 'D IND. 12'. A 'IA IND. TF' foi o '1 POT. o' dia da estação de reprodução de 64 dias. Usou-se o teste do 'c POT. 2' para comparar as taxas de serviço (TS), concepção (TC) e prenhez à 'IA IND. TF' ('TP IND. IATF'), às IAs de repasse e acumuladas. A TS e a TC das IAs de repasse não diferiu (P>0,10). Houve diferenças nas 'TP IND. IATF' (P<0,05), pois a 'TP IND. IATF' do 'G IND. E2' (5,4%) foi a mais baixa e a do Gc (34,5%) e 'G IND. hCG' (36,5%) tenderam (P<0,10) ser maiores que a do 'G IND. hCG/E2' (18,2%). Não houve efeito da hCG sobre as taxas de prenhez. O 'E IND. 2' reduziu a 'TP IND. IATF' e ao final da estação as vacas que receberam o 'E IND. 2' ('G IND. E2' + 'G IND. hCG/E2') tiveram 'TP IND. acum' (66,4%) mais baixa (P<0,05) de que aquelas (80,9%) que não receberam ('G IND. C' + 'G IND. hCG'). Em conclusão, as estratégias adotadas de manipulação luteínica ou folicular não aumentaram as taxas de prenhez em vacas Nelore após uma 'IA IND. TF'Strategies to reduce embryo mortality in cattle have been evaluated. Nelore (Bos taurus indicus) cows were submitted to timed artificial insemination (TAI - 'D IND. 0') after a GnRH/'PGF IND. 2a'/GnRH protocol. Cows were divided in the following groups: Control (Gc; n=55), hCG ('G IND. hCG'; n=55) received 3000 IU of hCG on 'D IND. 5' , 'E IND. 2' ('G IND. E2'; n=55) received 5 mg of Estradiol-'17 IND. b' ('E IND. 2') on 'D IND. 12' and hCG/'E IND. 2' ('G IND. hCG/E2'; n=55) received hCG on 'D IND. 5' and 'E IND. 2' on 'D IND. 12'. TAI represented the '1 POT. st' day of a 64 day breeding season. The 'qui POT. 2' test was applied to compare mating rate (MR), conception rate (CR) and pregnancy rate (PR) to TAI and AIs after natural estrus within the season as well as their accumulated figures at the end of the season. MR and CR for AIs within season did not differ (P>.10). PR to TAI differed (P<.05) among groups. GE2 showed the lowest rate (5,4%). Gc (34.5%) and 'G IND. hCG' (36.5%) tended (P<.10) to be higher than 'G IND. hCG/E2' (18.2%). There was no effect of hCG on pregnancy rates. 'E IND. 2' reduced PR to TAI and at the end of season which means that cows receiving 'E IND. 2' ('G IND. E2' + 'G IND. hCG/E2') had lower (66.4%; P<.05) PR than cows not receiving 'E IND. 2' ('G IND. C' + 'G IND. hCG'; 80.9%). In conlusion, the strategies to manipulate luteal and follicular function herein tested did not increase pregnancy rates in Nelore cows submitted to a TAIFAPESP 99/03313-9FAPESP 02/08363-

Immunohistochemical detection of receptors for oestrogen and progesterone in endometrial glands and stroma during the oestrous cycle in Nelore (Bos taurus indicus) cows

The aim of the present study was to monitor endometrial distribution and concentrations of oestrogen receptors 'alfa' (ER'alfa') and progesterone receptors (PR) by immunohistochemistry in Nelore cows (Bos taurus indicus) during the oestrous cycle. Blood samples were collected for progesterone measurement and endometrial samples were taken from the uterine horn contra lateral to the corpus luteum in 16 cows at days 0 (ovulation), 5, 9, 13 and 19 of the oestrous cycle. Immunostaining evaluation for ER'alfa' and PR in the glandular epithelium and uterine stroma was performed by two methods: positive nuclei counting and staining intensity of the nuclei. Specific positive staining reactions for both receptors were limited to cell nuclei and they were not identified in the cytoplasm. The proportion of ER'alfa' positive nuclei had a temporal variation throughout the oestrous cycle in both cell types evaluated and was higher in uterine stroma than the glandular epithelium (p < 0.05). The greatest proportion of ER'alfa' stained nuclei was observed at oestrus and during the initial and mid luteal phase (days 5, 9 and 13) (p < 0.05) in the glandular epithelium and at days 0, 5 and 9 in the uterine stroma (p < 0.01).The proportion of PR positive nuclei remained constant throughout the entire oestrous cycle for both cell types evaluated (p > 0.05). A higher proportion of PR positive nuclei was measured in the uterine stroma compared with the glandular epithelium (p < 0.05). Intensity of staining for ER'alfa' and PR varied throughout the oestrous cycle (p < 0.01). There was a higher staining intensity at days 0 and 5 in the stroma for ER'alfa' (p < 0.01) and PR (p < 0.01) and in the glandular epithelium at days 0, 5, 9 and 13 for ER'alfa' (p < 0.01) and at days 0, 5 and 9 for PR (p < 0.01) when compared with the other evaluated days. These data demonstrate that ER'alfa' and PR expression varied throughout the oestrous cycle in Nelore cows, in general with highest concentrations at oestrus and the lowest during the luteal phase. This is similar to patterns observed in Bos taurus tauru

Effect of eCG or estradiol benzoate associated with norgestomet on the conception rate of beef cows submitted to FTAI in the postpartum

Este estudo objetivou comparar as taxas de concepção, em vacas de corte no período pós-parto (PPP), tratadas com Gonadotrofina Coriônica Eqüina (eCG) ou Benzoato de Estradiol (BE), após o uso de Norgestomet submetidas à inseminação artificial em tempo fixo (IATF). A hipótese é que a administração de eCG ou BE aumenta as taxas de concepção. Vacas Nelore (n=138) e Brangus (n=63), lactantes, entre 26 e 118 dias do PPP, foram divididas em três grupos homogêneos e dentro de cada grupo subdivididas em dois blocos, um com um PPP < 45 dias (PPP1; n=107) e outro > 45 dias (PPP2; n=94). Todas as fêmeas receberam um implante auricular contendo 3mg de Norgestomet (Crestar®), seguido pela administração de 5mg de Valerato de Estradiol. Os implantes auriculares foram mantidos durante 10 dias. Na retirada dos implantes, as fêmeas receberam 1mL de solução fisiológica (n=68; Grupo Controle) ou 500UI de eCG (Folligon®; n=67; Grupo eCG) ou 1mg de Benzoato de Estradiol (Index; n=66; Grupo BE) 24 horas após a retirada do implante. A IATF foi realizada 54 horas após a retirada do implante. O diagnóstico de gestação foi realizado por ultra-sonografia 30 dias após a IATF. Houve interação entre os tratamentos e o PPP. No PPP1, a taxa de concepção foi maior no grupo eCG comparado ao BE (47,22% vs. 15,38%; P<0,01). No PPP2, as taxas de concepção dos grupos eCG e BE foram maiores que no grupo controle (41,93%, 44,44% vs. 22,22%; P<0,01). Conclui-se que vacas, com até 45 dias do PPP, o eCG associado ao Norgestomet aumenta as taxas de concepçãoThis study aimed to compare conception rates at the postpartum period (PPP) in beef cows which were administered either Equine Chorionic Gonadotrophin (eCG) or Estradiol Benzoate (EB) after Norgestomet and submitted to fixed-time artificial insemination (FTAI). The hypothesis was that the administration of eCG or EB enhances the conception rate. Lactating Nelore cows (n=138) and Brangus (n = 63), between 26 and 118 days of post partum period (PPP) were divided into three homogeneous groups, and subdivided in two blocks, inside each group one of them with a PPP = 45 days (PPP1; n=107) and another with a PPP > 45 days (PPP2; n=94). All cows received an auricular implant containing 3mg Norgestomet (Crestar®), followed by the administration of 5mg Estradiol Valerate. The auricular implants were kept during 10 days. Cows received 1mL saline solution (n=68, Control Group) or 500IU eCG (Folligon®; n=67; eCG Group) or 1mg Estradiol Benzoate (Index, n=66; EB Group) 24 hours after the removal of the implant. FTAI was made 54 hours after the implant removal. The pregnancy diagnosis was carried through ultrasonography 30 days after FTAI. There was an interaction between treatments and PPP. In the PPP1, the conception rate was higher in the eCG Group than in the EB Group (47.22% vs. 15.38%; P=0.01). In the PPP2, the conception rates of the eCG and EB Groups were higher than in the Control Group (41.93%, 44.44% vs. 22.22%: P=0.01). It was concluded that in cows up to 45 days of PPP, the eCG associated with Norgestomet enhances the conception rate

Quantification of interferon-tau during the maternal recognition of pregnancy in Bos taurus indicus cows

Durante o período crítico do reconhecimento materno, compreendido entre o 15° e 19° dias da gestação, o concepto deve sintetizar competentemente moléculas capazes de bloquear a síntese de prostaglandina F2a (pGF2a) e a luteólise. Em bovinos, a principal macromolécula protéica envolvida em tal bloqueio é o interferon-tau (IFN-r). Durante o período crítico, falhas neste reconhecimento determinam à mortalidade embrionária em até 40% das fêmeas inseminadas. Informações sobre o IFN-r em animais Bos taurus indicus, ainda são restritas. Este estudo objetivou uma avaliação quantitativa do IFN-r durante o período crítico do reconhecimento materno, em lavados uterinos obtidos por sonda de Foley (dias 14, 16 e 18 pósestro) oupost-mortem (dia 18 pós-estro). Para tanto, foram utilizadas fêmeas multíparas azebuadas (Bos taurus indicus), cíclicas ou prenhes, nos dias 14, 16 e 18 pós-estro. Para a obtenção dos lavados, os úteros foram infundidos com solução de Ringer Simples. Os lavados foram concentrados por ultra-f1ltração e liofilizados. As macromoléculas protéicas foram separadas por Eletroforese Unidimensional SDSPAGE, em gel com 15% de poliacrilamida. A quantificação do IFN-r nos lavados uterinos foi realizada por Western-Blotting e densitometria. Tanto nos lavados obtidos por sonda de Foley quanto nos post-mortem foi possível observar bandas de proteínas que apresentaram reação cruzada com os anticorpos utilizados no WesternBlotting. O IFN-T foi detectado apenas nos lavados uterinos post-mortem de vacas prenhes (P<0,05). A densidade óptica não foi afetada pelo dia do período crítico, estado (cíclico ou prenhe) ou interação dia x estado. Nos lavados post-mortem não houve efeito de peso do concepto ou concentração de progesterona plasmática no dia do lavado na densidade da banda protéica referente ao IFN-T . Concluiu-se que a detecção e quantificação do IFN-T no ambiente uterino de vacas azebuadas, nestas condições ) condições experimentais, é possível apenas em lavados uterinos obtidos post-mortemDuring the critical period of the maternal recognition, which occurs between days 15 and 19 of pregnancy, the conceptus must competendy synthesize molecules capable of blocking the synthesis of prostaglandin F2a (pGF2a) and luteolysis. In canle, the major macromolecule involved in suck blockage is the protein interferontau (IFN-i). During the critical period, failures in the recognition of pregnancy determine embryonic mortality on up to 40% of inseminated cows. Data about IFN-i in Bos taurus indicus are still scarce. Objective of this studywas to quantitatively evaluate the presence of IFN-i during the critical period for maternal recognition of pregnancy in uterine flushings obtained in vivo by Foley catheter (Days 14, 16 and 18 post estrus) or post-mortem (Day 18 post estrus). Multiparous, cyclic or pregnant zebu cows (Bos taurus indicus) on days 14,16 and 18 post estrus were used for in vivo or post mortem uterine flushing collection. In both cases, a Ringer solution was used to wash the uterus of cows. Uterine flushings were concentrated by ultra@tration and lyophilized. Prateins were separated by one-dimensional electrophoresis (SDS-PAGE) in a 15% polyacrilamide geL Interferontau quantification in uterine flushings was performed by western blotting and densitometry. Non-specific protein bands were observed in both in vivo and post mortem uterine flushings. Interferon-tau was detected only in uterine flushings obtained fram pregnant cows post-mortem (p<0.05). Optical density of protein bands was not affected by the day of the critical period, state (cyclic ar pregnant) or interaction day x state. There was no effect of the conceptus weight or progesterone concentration on the day of uterine flushing collection in the optical density of the IFN-i pratein bando It was concluded that the detection and quantification of IFN-i in the uterine environment of zebu cows, in these experimental? conditions, is only possible in uterine flushings obtained post-mortemFAPES