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1.
Reprod Fertil Dev ; 34(2): 36-51, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35231233

RESUMO

Genomic selection combined with in vitro embryo production (IVEP) with oocytes from heifer calves provides a powerful technology platform to reduce generation interval and significantly increase the rate of genetic gain in cattle. The ability to obtain oocytes with developmental competence from calves has been recognised for more than 60years. There is renewed interest in the potential of this reproductive technology as the beef and dairy industries seek to identify and multiply animals that satisfy consumer demand for efficient utilisation of natural resources, with minimal environmental impact and high product quality. Heifer calves show a good follicular response to FSH stimulation and oocytes can be recovered by ovum pick-up (OPU). However, the efficiency of OPU/IVEP remains lower for calves compared with peripubertal heifers and cows, in both indicus (Zebu, Bos indicus ) and taurus (Bos taurus ) breeds. Indicus cattle generally have more follicles, yield a greater number of oocytes, and have a better IVEP outcome, compared with taurus cattle. The treatment of prepubertal heifers with bovine somatotrophin (bST) and propylene glycol before OPU/IVEP has yet to show a major improvement in embryo production. Holstein (taurus) dairy heifers derived from different reproductive technologies (AI, MOET, OPU/IVEP) showed a similar age at puberty and first-lactation milk production. OPU/IVEP Holstein embryos transferred to beef or dairy cows likewise yielded heifers with the same performance. The gains in productivity that can be achieved with strategic use of OPU/IVEP in heifer calves make this a relevant and highly important reproductive technology in cattle breeding. Ongoing optimisation of the technology is needed for the potential of OPU/IVEP in young donors to be fully realised.


Assuntos
Fertilização in vitro , Oócitos , Animais , Bovinos , Embrião de Mamíferos , Feminino , Fertilização in vitro/veterinária , Lactação , Oócitos/fisiologia , Gravidez , Doadores de Tecidos
2.
Reprod Domest Anim ; 56(12): 1536-1542, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34510600

RESUMO

The aim of this study was to identify the impact of Trueperella pyogenes in cows with clinical endometritis (CE) on reproductive performance and milk production in affected cows. In total, 230 lactating Holstein dairy cows from six commercial dairy herds were sampled once between 28 and 33 days post-partum. Cows included in the present study did not receive antibiotic or anti-inflammatory treatments prior to the experimental period. Clinical endometritis (CE) was characterized as cow with vaginal mucus score = 3 (>50% of purulent vaginal discharge) and >18% polymorphonuclear neutrophilic leukocyte (PMNL). The body condition scores (BCS) and milk production were evaluated at the time of enrolment. The identification of isolated bacteria was carried out through the analysis of MALDI-TOF MS (matrix-assisted laser desorption ionization time-of-flight mass spectrometry). According to uterine health, three groups of dairy cows were formed: healthy control cows without T. pyogenes (n = 147), CE cows with T. pyogenes (n = 22) and CE cows without T. pyogenes (n = 61). CE cows with T. pyogenes had lower BCS, milk production and conception at first AI (p < .01) than CE cows without T. pyogenes and control cows. Furthermore, CE cows with T. pyogenes had higher (p < .01) service per pregnancy and had greater (p < .01) days to get pregnant than CE cows without T. pyogenes and control cows. This study demonstrates that CE cows with T. pyogenes had impaired reproductive performance and milk production when compared to cows without CE and CE cows without T. pyogenes. This information can contribute to a strategic treatment in cows affected by clinical endometritis, favouring the rational use of antibiotics on dairy farms.


Assuntos
Actinomycetaceae/patogenicidade , Infecções Bacterianas/veterinária , Doenças dos Bovinos , Endometrite , Animais , Bovinos , Doenças dos Bovinos/microbiologia , Endometrite/microbiologia , Endometrite/veterinária , Feminino , Lactação , Leite , Gravidez , Reprodução
3.
Biol Reprod ; 103(6): 1157-1170, 2020 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-32776148

RESUMO

Kisspeptin (KISS1) is encoded by the KISS1 gene and was initially found to be a repressor of metastasis. Natural mutations in the KISS1 receptor gene (KISS1R) were subsequently shown to be associated with idiopathic hypothalamic hypogonadism and impaired puberty. This led to interest in the role of KISS1 in reproduction. It was established that KISS1 had a fundamental role in the control of gonadotropin releasing hormone (GnRH) secretion. KISS1 neurons have receptors for leptin and estrogen receptor α (ERα), which places KISS1 at the gateway of metabolic (leptin) and gonadal (ERα) regulation of GnRH secretion. More recently, KISS1 has been shown to act at peripheral reproductive tissues. KISS1 and KISS1R genes are expressed in follicles (granulosa, theca, oocyte), trophoblast, and uterus. KISS1 and KISS1R proteins are found in the same tissues. KISS1 appears to have autocrine and paracrine actions in follicle and oocyte maturation, trophoblast development, and implantation and placentation. In some studies, KISS1 was beneficial to in vitro oocyte maturation and blastocyst development. The next phase of KISS1 research will explore potential benefits on embryo survival and pregnancy. This will likely involve longer-term KISS1 treatments during proestrus, early embryo development, trophoblast attachment, and implantation and pregnancy. A deeper understanding of the direct action of KISS1 at reproductive tissues could help to achieve the next step change in embryo survival and improvement in the efficiency of assisted reproductive technology.


Assuntos
Implantação do Embrião/fisiologia , Kisspeptinas/metabolismo , Gado/fisiologia , Ovário/fisiologia , Técnicas de Reprodução Assistida/veterinária , Animais , Feminino
4.
Mol Reprod Dev ; 87(2): 206-222, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31944459

RESUMO

Cell-cell adhesion molecules have critically important roles in the early events of reproduction including gamete transport, sperm-oocyte interaction, embryonic development, and implantation. Major adhesion molecules involved in reproduction include cadherins, integrins, and disintegrin and metalloprotease domain-containing (ADAM) proteins. ADAMs on the surface of sperm adhere to integrins on the oocyte in the initial stages of sperm-oocyte interaction and fusion. Cadherins act in early embryos to organize the inner cell mass and trophectoderm. The trophoblast and uterine endometrial epithelium variously express cadherins, integrins, trophinin, and selectin, which achieve apposition and attachment between the elongating conceptus and uterine epithelium before implantation. An overview of the major cell-cell adhesion molecules is presented and this is followed by examples of how adhesion molecules help shape early reproductive events. The argument is made that a deeper understanding of adhesion molecules and reproduction will inform new strategies that improve embryo survival and increase the efficiency of natural mating and assisted breeding in cattle.


Assuntos
Proteínas ADAM/metabolismo , Caderinas/metabolismo , Desintegrinas/metabolismo , Implantação do Embrião/fisiologia , Integrinas/metabolismo , Oócitos/fisiologia , Interações Espermatozoide-Óvulo/fisiologia , Espermatozoides/fisiologia , Animais , Bovinos , Adesão Celular/fisiologia , Feminino , Masculino , Gravidez
5.
Reprod Fertil Dev ; 32(6): 539-552, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32024582

RESUMO

Survival of the embryo and establishment of a pregnancy is a critical period in the reproductive function of female cattle. This review examines how the transforming growth factor-ß (TGFB) superfamily (i.e. bone morphogenetic protein (BMP) 15, growth differentiation factor (GDF) 9, anti-Müllerian hormone (AMH)) and interferon-τ (IFNT) affect ovarian function and embryo development. The oocyte in a primary follicle secretes BMP15 and GDF9, which, together, organise the surrounding granulosa and theca cells into the oocyte-cumulus-follicle complex. At the same time, the granulosa secretes AMH, which affects the oocyte. This autocrine-paracrine dialogue between the oocyte and somatic cells continues throughout follicle development and is fundamental in establishing the fertilisation potential and embryo developmental competency of oocytes. The early bovine embryo secretes IFNT, which acts at the uterine endometrium, corpus luteum and blood leucocytes. IFNT is involved in the maternal recognition of pregnancy and immunomodulation to prevent rejection of the embryo, and supports progesterone secretion. Manipulation of BMP15, GDF9, AMH and IFNT in both invivo and invitro studies has confirmed their importance in reproductive function in female cattle. This review makes the case that a deeper understanding of the biology of BMP15, GDF9, AMH and IFNT will lead to new strategies to increase embryo survival and improve fertility in cattle. The enhancement of oocyte quality, early embryo development and implantation is considered necessary for the next step change in the efficiency of natural and assisted reproduction in cattle.


Assuntos
Comunicação Celular , Desenvolvimento Embrionário , Fertilidade , Interferon Tipo I/metabolismo , Ovário/metabolismo , Proteínas da Gravidez/metabolismo , Proteínas da Superfamília de TGF-beta/metabolismo , Animais , Hormônio Antimülleriano/metabolismo , Proteína Morfogenética Óssea 15/metabolismo , Bovinos , Feminino , Fator 9 de Diferenciação de Crescimento/metabolismo , Gravidez , Técnicas de Reprodução Assistida/veterinária , Transdução de Sinais
6.
J Dairy Sci ; 101(5): 4595-4614, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29550131

RESUMO

The objectives of the current study were to determine the association between body condition score change during the dry period (ΔBCS) and postpartum health and reproductive and productive performance of Holstein cows. Data from 16,104 lactations from 9,950 parous cows from 2 dairies located in the San Joaquin Valley of California were used. Within dairy, cows were scored for body condition at dry off and parturition by the same herd workers, who were trained by veterinarians from the Veterinary Medicine Teaching and Research Center of the University of California Davis. Cows were classified as having excessive loss of BCS (ΔBCS ≤-0.75; n = 1,604), moderate loss of BCS (ΔBCS = -0.5 to -0.25; n = 6,430), no change in BCS (ΔBCS = 0; n = 4,819), and gained BCS (ΔBCS ≥0.25; n = 3,251). Data regarding morbidity, mortality, and reproductive and productive performance were recorded until 305 d postpartum or until cows were dried off or left the herd. Loss of BCS during the dry period was associated with greater incidence of uterine disease and indigestion. Additionally, loss of BCS during the dry period was associated with greater likelihood of treatment with antimicrobials, anti-inflammatories, and supportive therapy. Loss of BCS during the dry period was associated with reduced likelihood of pregnancy after the first and second postpartum inseminations. Cows that gained BCS during the dry period had greater yield of milk, fat, and protein and had reduced somatic cell linear score in the subsequent lactation. In the current study, loss of BCS during the dry period was a predisposing factor associated with health disorders and reduced productive and reproductive performance in Holstein cows.


Assuntos
Período Pós-Parto/fisiologia , Animais , California , Bovinos , Dieta/veterinária , Feminino , Lactação , Leite/metabolismo , Parto , Gravidez , Reprodução
7.
J Assist Reprod Genet ; 32(4): 543-9, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25701140

RESUMO

PURPOSE: This study aimed to induce follicular wave emergence (FWE) using pharmacological (recombinant hCG administration) or mechanical (aspiration of dominant follicle) interventions in infertile women. METHODS: Sixteen infertile women (≤35 years) with indications for in vitro fertilization due to tubal and/or male factor infertility were randomized into three groups: control (n = 6), pharmacological (n = 5) and mechanical (n = 5) groups. Women in both experimental groups underwent serial transvaginal sonograms (TVS) from menstrual cycle day 10 until identification of a dominant follicle ≥15 mm. Women in the pharmacological group received 250 µg of recombinant-hCG to induce ovulation, and resumed serial TVS 2 days later. In the mechanical group, dominant and subordinate follicles ≥10 mm were aspirated, and daily TVS was resumed on the following day. An increased pool of follicles ≥5 and ≤9 mm after interventions characterized FWE. Women in the control group underwent ovulation induction (OI) with 150 IU/day of recombinant follicle-stimulating hormone started on menstrual cycle day 3 (D3). OI was started on the day of FWE in the experimental groups. Endometrial asynchrony with development of the embryo was expected in the experimental groups. Therefore, all viable embryos were cryopreserved and transferred in an endometrial-stimulated cycle. RESULTS: The number of follicles ≥5 and ≤9 mm increased after the interventions in both experimental groups (p < .001), indicating induction of FWE. OI outcomes were similar among the groups. CONCLUSIONS: The pharmacological and mechanical interventions are efficient in inducing FWE; outcomes of OI synchronized with FWE should be further investigated.


Assuntos
Hormônio Foliculoestimulante/uso terapêutico , Infertilidade Feminina/terapia , Fase Luteal/efeitos dos fármacos , Folículo Ovariano/fisiologia , Indução da Ovulação/métodos , Técnicas de Reprodução Assistida , Adulto , Gonadotropina Coriônica/farmacologia , Gonadotropina Coriônica/uso terapêutico , Feminino , Hormônio Foliculoestimulante/farmacologia , Humanos , Infertilidade Feminina/tratamento farmacológico , Folículo Ovariano/crescimento & desenvolvimento , Projetos Piloto , Resultado do Tratamento
8.
J Anim Sci ; 1022024 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-38586898

RESUMO

The pleomorphic adenoma gene1 (PLAG1) encodes a DNA-binding, C2H2 zinc-finger protein which acts as a transcription factor that regulates the expression of diverse genes across different organs and tissues; hence, the name pleomorphic. Rearrangements of the PLAG1 gene, and/or overexpression, are associated with benign tumors and cancers in a variety of tissues. This is best described for pleomorphic adenoma of the salivary glands in humans. The most notable expression of PLAG1 occurs during embryonic and fetal development, with lesser expression after birth. Evidence has accumulated of a role for PLAG1 protein in normal early embryonic development and placentation in mammals. PLAG1 protein influences the expression of the ike growth factor 2 (IGF2) gene and production of IGF2 protein. IGF2 is an important mitogen in ovarian follicles/oocytes, embryos, and fetuses. The PLAG1-IGF2 axis, therefore, provides one pathway whereby PLAG1 protein can influence embryonic survival and pregnancy. PLAG1 also influences over 1,000 other genes in embryos including those associated with ribosomal assembly and proteins. Brahman (Bos indicus) heifers homozygous for the PLAG1 variant, rs109815800 (G > T), show greater fertility than contemporary heifers with either one, or no copy, of the variant. Greater fertility in heifers homozygous for rs109815800 could be the result of early puberty and/or greater embryonic survival. The present review first looks at the broader roles of the PLAG1 gene and PLAG1 protein and then focuses on the emerging role of PLAG1/PLAG1 in embryonic development and pregnancy. A deeper understanding of factors which influence embryonic development is required for the next transformational increase in embryonic survival and successful pregnancy for both in vivo and in vitro derived embryos in cattle.


The pleomorphic adenoma gene1 (PLAG1) produces PLAG1 protein which, by binding to specific regions on DNA, influences the activity of other genes that regulate many body functions. One gene is insulin-like growth factor 2 (IGF2) which controls cell metabolism and growth. The PLAG1 gene is particularly active during embryonic and fetal growth, and through IGF2 determines stature later in life. IGF2 protein is also very important in early embryonic development. This review explores the hypothesis that PLAG1 is an important determinant of embryonic survival and the establishment of pregnancy in mammals.


Assuntos
Proteínas de Ligação a DNA , Animais , Bovinos/genética , Feminino , Gravidez , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Reprodução/genética , Desenvolvimento Embrionário/genética , Fator de Crescimento Insulin-Like II/genética , Fator de Crescimento Insulin-Like II/metabolismo
9.
Reprod Fertil Dev ; 25(7): 998-1011, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23106933

RESUMO

Equine chorionic gonadotrophin (eCG) has been widely used in superovulation and artificial insemination programmes and usually promotes an increase in corpus luteum (CL) volume and stimulates progesterone production. Therefore, to identify eCG-regulated genes in the bovine CL, the transcriptome was evaluated by microarray analysis and the expression of selected genes was validated by qPCR and western blot. Eighteen Nelore crossbred cows were divided into control (n=5), stimulated (n=6) and superovulated groups (n=7). Ovulation was synchronised using a progesterone device-based protocol. Stimulated animals received 400 IU of eCG at device removal and superovulated animals received 2000 IU of eCG 4 days prior. Corpora lutea were collected 7 days after gonadotrophin-releasing hormone administration. Overall, 242 transcripts were upregulated and 111 transcripts were downregulated in stimulated cows (P ≤ 0.05) and 111 were upregulated and 113 downregulated in superovulated cows compared to the control animals (1.5-fold, P ≤ 0.05). Among the differentially expressed genes, many were involved in lipid biosynthesis and progesterone production, such as PPARG, STAR, prolactin receptors and follistatin. In conclusion, eCG modulates gene expression differently depending on the treatment, i.e. stimulatory or superovulatory. Our data contribute to the understanding of the pathways involved in increased progesterone levels observed after eCG treatment.


Assuntos
Bovinos/metabolismo , Corpo Lúteo/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Gonadotropinas Equinas/administração & dosagem , Superovulação , Animais , Corpo Lúteo/anatomia & histologia , Corpo Lúteo/efeitos dos fármacos , Feminino , Hormônio Liberador de Gonadotropina/administração & dosagem , Inseminação Artificial/métodos , Inseminação Artificial/veterinária , Lipídeos/biossíntese , Lipídeos/genética , Análise em Microsséries/veterinária , Indução da Ovulação/métodos , Indução da Ovulação/veterinária , Progesterona/administração & dosagem , Progesterona/biossíntese , Progesterona/genética
10.
Animal ; 17 Suppl 1: 100764, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37567675

RESUMO

The domestic buffalo (Bubalus bubalis), also known as water buffalo, comprises two sub-species the River buffalo (B. bubalis ssp. bubalis; 50 chromosomes) and the Swamp buffalo (ssp. carabanensis; 48 chromosomes). Domestic buffaloes are a globally significant livestock species. In South Asia, the River buffalo is a primary source of milk and meat and has a very important role in food security. The River buffalo also supports high-value, differentiated food production in Europe and the Americas. The Swamp buffalo is an important draft animal and a source of food in Southeast Asia and East Asia. The growing importance of buffaloes requires that they undergo an accelerated rate of genetic gain for efficiency of production, product quality, and sustainability. This will involve the increased use of assisted reproduction. The initial application of reproductive technology in buffaloes had variable success as it relied on the adoption of procedures developed for cattle. This included artificial insemination (AI), sperm cryopreservation, and embryo technologies such as cloning and in vitro embryo production (IVEP). Reproductive technology has been progressively refined in buffaloes, and today, the success of AI and IVEP is comparable to cattle. Ovarian follicular superstimulation (superovulation) combined with in vivo embryo production results in low embryo recovery in buffaloes and has limited practical application. The contribution of elite female buffaloes to future genetic improvement will therefore rely mainly on oocyte pickup and IVEP. This will include IVEP from females before puberty to reduce generation intervals. This review provides for the first time a clear chronology on the development, adoption, and impact, of assisted reproduction in domestic buffaloes.


Assuntos
Búfalos , Sêmen , Bovinos/genética , Animais , Feminino , Masculino , Búfalos/genética , Maturidade Sexual , Reprodução/fisiologia , Inseminação Artificial/veterinária
11.
Theriogenology ; 196: 106-111, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36413866

RESUMO

Clinical endometritis causes serious economic losses in dairy farms, mainly due to its negative health impact on fertility and milk production, as well as the additional costs of medicines used to treat the affected animals. The therapy for uterine diseases is principally performed with antibiotic treatment; however, its indiscriminate use in dairy herds can favor the increase in the resistance of pathogenic bacteria, leading to treatment failures. In this regard, the use of unconventional treatment may be a good option to reduce the use of antimicrobials in milk production. The objective of the present study was to evaluate the antibacterial activity of cinnamon, oregano, and thyme essential oils, and their combinations, against bovine uterine pathogens. The antibacterial activities of these essential oils were evaluated by the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC), and Fractional Inhibitory Concentration (FIC) indices against Escherichia coli and Trueperella pyogenes, which were isolated from dairy cows with clinical endometritis. Among the essential oils evaluated, the lowest MIC and MBC values observed were obtained with cinnamon essential oil alone. The association among essential oils showed different kinds of interactions, and in some situations, antagonism was observed. This study demonstrated a promising antimicrobial activity of cinnamon's essential oil, indicating that it has excellent potential to be explored as a possible alternative in the treatment of clinical endometritis in dairy cows.


Assuntos
Óleos Voláteis , Origanum , Animais , Bovinos , Feminino , Cinnamomum zeylanicum , Óleos Voláteis/farmacologia , Escherichia coli , Óleos de Plantas
12.
Sci Rep ; 13(1): 8176, 2023 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-37210395

RESUMO

1H NMR-based metabolomics was used to study the effect of abrupt weaning on the blood metabolome of beef calves. Twenty Angus calves (258 ± 5 kg BW; 5 to 6 months old) were randomly assigned to a non-weaned (NW) group that remained grazing with their dam or a weaned (W) group that underwent abrupt separation from their dam to a separate paddock on d 0 of the study. Body weight, behaviour, and blood samples for cortisol and metabolomics were measured at d 0, 1, 2, 7, and 14 of the study. On d 1 and 2, W calves spent less time grazing and ruminating, and more time vocalising and walking, had a greater concentration of cortisol, NEFA, 3-hydroxybutyrate, betaine, creatine, and phenylalanine, and lesser abundance of tyrosine (P < 0.05) compared to NW calves. Compared to NW calves at d 14, W calves had greater (P < 0.01) relative abundance of acetate, glucose, allantoin, creatinine, creatine, creatine phosphate, glutamate, 3-hydroxybutyrate, 3-hydroxyisobutyrate, and seven AA (alanine, glutamate, leucine, lysine, phenylalanine, threonine and valine) but lesser (P < 0.05) relative abundance of low density and very low-density lipids, and unsaturated lipids. Both PCA and OPLS-DA showed no clustering or discrimination between groups at d 0 and increasing divergence to d 14. Blood metabolomics is a useful tool to quantify the acute effects of stress in calves during the first 2 days after abrupt weaning, and longer-term changes in carbohydrate, lipid and protein metabolism due to nutritional changes from cessation of milk intake and greater reliance on forage intake.


Assuntos
Creatina , Hidrocortisona , Bovinos , Animais , Ácido 3-Hidroxibutírico , Desmame , Peso Corporal , Carboidratos , Glutamatos , Ração Animal/análise , Dieta/veterinária
13.
Reprod Fertil Dev ; 24(1): 272-7, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22394969

RESUMO

Although embryo transfer technology has been used commercially in cattle for many years, the inefficiency of oestrus detection, especially in recipients, has limited the widespread application of this technology. The most useful alternative to increase the number of recipients utilised in an embryo transfer program is the use of protocols that allow for embryo transfer without the need for oestrus detection, usually called fixed-time embryo transfer (FTET). Most current FTET protocols are based on progestin-releasing devices combined with oestradiol or GnRH, which control and synchronise follicular wave dynamics and ovulation. Conception rates to a single FTET have been reported to be similar to those after detection of oestrus, but pregnancy rates are higher because these treatments have increased the proportion of recipients that receive an embryo. Recent changes to treatments for FTET, such as the administration of eCG, have resulted in increased pregnancy rates and provide opportunities to make these treatments easier to perform on farm.


Assuntos
Bovinos/fisiologia , Transferência Embrionária/métodos , Sincronização do Estro/métodos , Taxa de Gravidez , Prenhez/fisiologia , Animais , Cruzamento , Gonadotropina Coriônica/uso terapêutico , Detecção do Estro , Feminino , Ovulação/fisiologia , Gravidez
14.
Theriogenology ; 167: 1-12, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33743503

RESUMO

Early embryo development, implantation and pregnancy involve a complex dialogue between the embryo and mother. In cattle this dialogue starts as early as days 3-4 when the embryo is still in the oviduct, and it continues to implantation. Immunological processes involving cytokines, mast cells and macrophages form an important part of this dialogue. Amongst the cytokines, interleukin-6 (Il-6) and leukemia inhibitory factor (LIF) are secreted by both the embryo and uterine endometrium and form part of an ongoing and reciprocating dialogue. Mast cells and macrophages populate the uterine endometrium during embryo development and are involved in achieving the correct balance between inflammatory and anti-inflammatory reactions at the uterus that are associated with embryo attachment and implantation. Embryo loss is the major cause of reproductive wastage in cattle, and livestock generally. A deeper understanding of immunological processes during early embryo development will help to achieve the next step change in the efficiency of natural and assisted breeding.


Assuntos
Implantação do Embrião , Embrião de Mamíferos , Animais , Bovinos , Comunicação , Desenvolvimento Embrionário , Endométrio , Feminino , Gravidez , Útero
15.
Reprod Fertil Dev ; 22(1): 67-74, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20003847

RESUMO

Numerous studies have shown that it is possible to manipulate follicular and luteal dynamics, thereby eliminating the need for oestrus detection in embryo transfer (ET) programmes. Fixed-time ET (FTET) protocols are based on the use of gonadotrophin-releasing hormone (GnRH) and prostaglandin (PG) F or progesterone/progestogen (P4)-releasing devices and oestradiol. The FTET protocols increases the proportion of recipients transferred, and therefore pregnancy rates, compared with the use of PGF followed by ET 7 days after oestrus. Furthermore, the addition of equine chorionic gonadotrophin (eCG) to the P4 and oestradiol-based FTET protocols results in an even higher proportion of recipients transferred, and thus higher pregnancy rates. The beneficial effect of eCG treatment may be related to increased growth of the dominant follicle and increased plasma P4 concentrations during the subsequent luteal phase. In Bos taurus x Bos indicus recipients, pregnancy rates were positively correlated with the diameter of the corpus luteum (CL) and the number of CL at ET. When repeat-breeder Holstein cows were used as recipients, FTET protocols increased number of recipients transferred and pregnancy rates compared with the traditional PGF-based synchronisation protocols. In conclusion, the use of FTET protocols eliminates the need for the detection of oestrus and results in a greater proportion of recipients transferred and satisfactory pregnancy rates. Thus, FTET optimises the use of recipients, reducing labour and animal handling and facilitating the use of ET.


Assuntos
Bovinos/embriologia , Transferência Embrionária/veterinária , Sincronização do Estro/métodos , Clima Tropical , Animais , Cruzamento/métodos , Transferência Embrionária/métodos , Sincronização do Estro/sangue , Feminino , Gravidez , Taxa de Gravidez , Progesterona/sangue , América do Sul
16.
Theriogenology ; 155: 1-11, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32562738

RESUMO

Heat stress (HS) has a pronounced deleterious effect on fertility in dairy herds throughout the world, especially in hot and humid summer months in tropical and subtropical areas. Summer HS reduces feed intake and increases negative energy balance, induces changes in ovarian follicular dynamics, reduces estrus detection rates and alters oviductal function leading to fertilization failure and early embryonic death. Furthermore, oocytes harvested from lactating cows during summer HS have a decreased ability to develop to the blastocyst stage after in vitro fertilization when compared with oocytes harvested during winter. The present manuscript describes the detrimental effect of HS on reproduction, with emphasis on preovulatory oocytes and carry over effects of HS on embryo development and P/AI. Embryo transfer (ET) has been an effective tool to reestablish fertility during HS because it bypasses the damage to the oocyte and early embryo caused by hyperthermia. Therefore, a management strategy to maintain increased fertility throughout the year would be to produce embryos during the cooler months, when oocyte quality is greater, and use them to produce pregnancies during the periods of HS, when oocyte quality is compromised. However, this strategy only can be implemented using cryopreserved embryos, what is still limiting. During the warmer months, the use of heifers or non-lactating cows as oocyte or embryo donors may facilitate embryo production, mainly because of the lesser deleterious effects of HS comparing to lactating cows. Also, genetic selection of donors for thermoregulation ability is one potential strategy to mitigate effects of HS and increase embryo production during the warmer months. These alternatives enable the transference of fresh embryos with more efficiency during HS periods. Additionally, the application of timed ET protocols, which avoid the need for estrus detection in recipients, has facilitated management and improved the efficiency of ET programs during HS.


Assuntos
Doenças dos Bovinos , Transtornos de Estresse por Calor , Infertilidade , Animais , Bovinos , Transferência Embrionária/veterinária , Feminino , Transtornos de Estresse por Calor/veterinária , Resposta ao Choque Térmico , Infertilidade/veterinária , Lactação , Gravidez
17.
Theriogenology ; 150: 186-192, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32000994

RESUMO

Seasonal breeding in buffalo is influenced by exogenous (photoperiod, climate, nutrition, management) and endogenous (hormones, genotype) factors. Buffalo are negatively photoperiodic and show a natural increase in fertility during decreasing day length. The hormone melatonin is produced by the pineal gland and has a fundamental role in photoperiodic time measurement within the brain. This drives annual cycles of gonadotropin secretion and gonadal function in buffaloes. Some melatonin is released into the systemic circulation and, together with peripherally produced melatonin, acts at somatic tissues. In the ovaries and testes of buffalo, melatonin acts as an antioxidant and scavenges oxygen free radicals to reduce both oxidative stress and apoptosis. This has beneficial effects on gametogenesis and steroidogenesis. Female buffalo treated with melatonin show an improved response to estrus synchronization protocols in out-of-season breeding. Melatonin acts through melatonin receptors MT1 and MT2 and the gene for MT1 (MTNR1A) is polymorphic in buffaloes. Single nucleotide polymorphisms (SNPs) in gene MTNR1A have been associated with fertility in female buffalo. The knowledge and tools are available to lift the reproductive performance of buffalo. This is highly important as the global demand for nutritious buffalo food products has undergone a sharp rise, and continues to grow. Buffalo can make an important contribution to affordable, nutritious animal protein. This will help address global nutritional security.


Assuntos
Búfalos/fisiologia , Reprodução/fisiologia , Estações do Ano , Animais , Feminino , Melatonina/metabolismo , Melatonina/farmacologia , Fotoperíodo
18.
Theriogenology ; 125: 277-284, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30497026

RESUMO

Nutrition is of fundamental importance in reproductive function of female beef cattle. Nutrition determines live weight (LW) and body condition score (BCs) and both were found more than 50 years ago to underpin fertility in pubertal heifers and postpartum cows. In heifers, LW at weaning and average daily gain (ADG) after weaning determines age and LW at puberty, and subsequent lifetime fertility. In cows, BCS at parturition is the most important factor that determines the period to re-conception postpartum. Nutrition establishes systemic metabolic homeostasis. Metabolic hormones such as leptin, IGF1 and Ghrelin act as signaling factors that regulate activity of GnRH neurons in the hypothalamus. The release of GnRH and function of the reproductive endocrine system is determined by the balance of positive signals (IGF1, leptin) and negative signals (Ghrelin) at GnRH neurons. Nutritional factors also directly influence ovarian follicles, oocytes and embryos. Saturated fatty acids (FAs) are detrimental to oocytes and embryos whilst unsaturated FAs may be beneficial. The ratio of FAs (saturated, monounsaturated, polyunsaturated) is likely the key to optimal reproductive function. Nutrition controls the levels of metabolic hormones (leptin, IGF1, Ghrelin) and metabolic factors (FAs) and both have major roles in reproduction in female beef cattle.


Assuntos
Composição Corporal , Bovinos/fisiologia , Metabolismo Energético , Estado Nutricional , Animais , Feminino , Gravidez
19.
Anim Reprod ; 15(Suppl 1): 1003-1014, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-36249848

RESUMO

As our understanding of ovarian function in cattle has improved, our ability to control it has also increased. Luteal function in cattle has been studied in detail, and prostaglandin F2α has been used for several years for the elective induction of luteal regression. More recently, follicle wave dynamics has been studied and protocols designed to induce follicular wave emergence and ovulation have reduced, and even eliminated, the need for estrus detection. The addition of progestin-releasing devices, estradiol, GnRH and equine chorionic gonadotropin (eCG) have provided opportunities for fixed-time AI (FTAI) and possibilities for increased pregnancy rates. In embryo transfer programs, these same treatments have eliminated the need for estrus detection, permitting fixed-time embryo transfer and the initiation of superstimulatory treatments without regard to day of the estrous cycle. Collectively, new treatment protocols have facilitated the application of assisted reproductive technologies, and this is especially true in South America. Over the last 20 years, the use of AI in South America has increased, due largely to the use of FTAI. There has been more than a 10-fold increase in the use of FTAI in Brazil with more than 11 million treatments in 2016, representing 85% of all AI. Similar trends are occurring in Argentina and Uruguay. Production of in vivo-derived (IVD) embryos has remained relatively stable over the years, but in vitro embryo production (IVP) has increased dramatically over the past 10 to 15 years, especially in Brazil where more than 300,000 IVP embryos were produced in 2010. World-wide, more than 666,000 bovine IVP embryos were produced in 2016, of which more than 57% were produced in South America. The use of assisted reproductive technologies has facilitated the dissemination of improved genetics and increased reproductive performance; other South American countries are now following suit.

20.
Anim Reprod ; 15(Suppl 1): 952-962, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-36249833

RESUMO

Fixed-time artificial insemination (FTAI) has been widely applied in South America within the last 20 years for the genetic improvement of commercial beef herds. Most FTAI treatments for beef cattle used in South America are based on the use of progesterone (P4) releasing devices and estradiol to synchronize follicle wave emergence, with pregnancies per AI (P/AI) ranging from 40 to 60%. More recent protocols focusing on extending the interval from device removal to FTAI (i.e. increasing the growing period of the ovulatory follicle) have been reported to improve P/AI in beef cattle. These new protocols and the more traditional FTAI protocols have also been adapted for use with sexed-sorted semen with acceptable P/AI in beef cattle. Finally, color-flow Doppler ultrasonography has been incorporated recently to determine the vascularity of the CL and thereby detect pregnancy as early as Day 22 after the first AI for re- synchronization of ovulation for a second FTAI in non- pregnant animals. In summary, FTAI protocols have facilitated the widespread application of AI in South American beef cattle by allowing for the insemination and re-insemination of herds during a defined breeding season, without the necessity of clean up bulls to achieve high pregnancy rates.

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