RESUMO
Pesticides are used worldwide to control arthropod parasites in cattle herds. The indiscriminate and/or inappropriate use of pesticides without veterinary guidance is a reality in several countries of South America. Improper pesticide use increases the chances of contamination of food and the environment with chemical pesticides and their metabolites. Reduction of these contamination events is an increasing challenge for those involved in livestock production. The horn fly, Haematobia irritans (Linnaeus) (Diptera: Muscidae), is one of the most economically important parasites affecting cattle herds around the world. As such, horn fly control efforts are often required to promote the best productive performance of herds. Pesticide susceptibility bioassays revealed that pyrethroid resistance was widespread and reached high levels in horn fly populations in the Brazilian state of Rondônia. The knockdown resistance (kdr) sodium channel gene mutation was detected in all horn fly populations studied (n = 48), and the super kdr sodium channel gene mutation was found in all homozygous resistant kdr individuals (n = 204). Organophosphate resistance was not identified in any of the fly populations evaluated.
Assuntos
Resistência a Inseticidas/genética , Inseticidas/farmacologia , Muscidae/efeitos dos fármacos , Organofosfatos/farmacologia , Piretrinas/farmacologia , Animais , Brasil , Muscidae/genéticaRESUMO
The aim of this study was to determine the effects of the cumulative gain in expertise in carrying out handmade cloning (HMC) procedures on embryo yield and pregnancy outcome in cattle. Results from in vitro and in vivo embryo development after HMC during three periods of 7 months, separated by 3-month intervals, were compiled and designated as P1, P2 and P3. Blastocyst yield, morphological quality and stage of development, and pregnancy per embryo transfer (ET) on Day 30 of gestation were compared. Zona-intact oocytes were activated chemically in each experiment replicate, and development of parthenogenetic blastocysts was used as a control measurement of oocyte quality and in vitro culture conditions. A total of 21,231 cumulus-oocyte complexes (COCs) were in vitro-matured, with 5,432, 10,721 and 5078 COCs used in 16, 18 and 10 replicates for P1, P2 and P3, respectively. Cloned blastocyst yields on Day 7 increased from 15.5% (124/798) in P1 to 21.6% (309/1428) and 36.6% (280/764) in P2 and P3, respectively. No differences were observed in blastocyst development of parthenogenetic embryos, which average 30.0, 37.6, and 36.4% in P1, P2, and P3, respectively. A 10-fold higher probability of obtaining cloned blastocysts at more advanced stages of development and of higher morphological grade was seen during P3 compared with P1. Pregnancy per ET on Day 30 also increased with gain in expertise, being 6.7% (2/30), 20.8% (10/48) and 40.0% (24/60) for P1, P2 and P3, respectively. The relative efficiency for the establishment of pregnancies (per total COC) increased from 0.04% (1:2716) in P1 to 0.22% (1:460) in P2, reaching 0.47% (1:212) in P3. Results demonstrated a gradual improvement in in vitro and in vivo embryo development over time after establishment of HMC procedures in the laboratory, highlighting the importance of gaining experience and technical skills on the overall cloning efficiency.
Assuntos
Blastocisto/citologia , Clonagem de Organismos/veterinária , Oócitos/citologia , Animais , Blastocisto/fisiologia , Bovinos , Técnicas de Cultura de Células/veterinária , Clonagem de Organismos/métodos , Eficiência , Desenvolvimento Embrionário , Feminino , Oócitos/fisiologia , Partenogênese , Gravidez , Resultado da Gravidez/veterináriaRESUMO
Cloning procedures often interfere with conceptus growth and life ex utero, in a set of symptoms known as abnormal offspring syndrome (AOS). The aim of the present study was to compare the developmental pattern of in vivo-derived (IVD), IVF-derived and handmade cloning-derived (NT-HMC) Day 225 bovine concepti using established procedures. Pregnancy diagnosis was performed on Day 30 following blastocyst transfer on Day 7. Conceptus morphometry was assessed by ultrasonography on Day 51, and on Day 225 pregnant cows were killed for morphological examination of concepti. Pregnancy outcome was similar between groups, with greater pregnancy losses in the first trimester (70.6%) and smaller fetuses on Day 51 in the NT-HMC group than in the IVD (14.3%) and IVF (20.0%) groups. However, NT-HMC-derived concepti were twofold larger on Day 225 of gestation than controls. A higher frequency (63.5%) of placentomes larger than the largest in the IVD group was observed in the NT-HMC group, which may be relevant to placental function. Conceptus traits in the IVF group were similar to the IVD controls, with only slight changes in placentome types. Morphological changes in cloned concepti likely affected placental function and metabolism, disrupting the placental constraining mechanism on fetal growth in mid- to late pregnancy.
Assuntos
Clonagem de Organismos , Desenvolvimento Embrionário/fisiologia , Animais , Bovinos , Transferência Embrionária/veterinária , Feminino , Fertilização in vitro/veterinária , Técnicas de Transferência Nuclear/veterinária , Gravidez , Resultado da Gravidez , Ultrassonografia Pré-Natal/veterináriaRESUMO
Postpartum anovulation is a natural process that is observed in most mammals, including women. In lactating dairy cows, the interval from calving to first ovulation typically averages 4 to 5 weeks, but a substantial proportion of cows have not resumed estrous cyclicity by 60 days postpartum. Extended delay in resumption of first postpartum ovulation is known to exert long-lasting detrimental effects on fertility in dairy cows including the lack of spontaneous estrus and subsequent timely insemination postpartum, but when anovular cows have the estrous cycle synchronized for artificial insemination (AI), still pregnancy per AI is reduced and the risk of pregnancy loss increased. Many risk factors exist for extended postpartum anovulatory periods such as negative nutrient balance and diseases, and these risk factors are also known to depress fertility by themselves. A key feature in anovular cows when inseminated is that they develop the ovulatory follicle under subluteal or low concentrations of progesterone. Progesterone from the corpus luteum is pivotal for follicle development, oocyte competence, embryo growth, and endometrial function; however, many of these effects exerted by progesterone are mediated either by secretion of gonadotropins influencing follicular function and oocyte competence or by endometrial histotroph secretion influencing embryo/conceptus growth and developmental biology
Assuntos
Feminino , Animais , Bovinos , Bovinos/embriologia , Infertilidade Feminina/classificação , Infertilidade Feminina/complicações , Infertilidade Feminina/diagnóstico , Ovulação , ProgesteronaRESUMO
Postpartum anovulation is a natural process that is observed in most mammals, including women. In lactating dairy cows, the interval from calving to first ovulation typically averages 4 to 5 weeks, but a substantial proportion of cows have not resumed estrous cyclicity by 60 days postpartum. Extended delay in resumption of first postpartum ovulation is known to exert long-lasting detrimental effects on fertility in dairy cows including the lack of spontaneous estrus and subsequent timely insemination postpartum, but when anovular cows have the estrous cycle synchronized for artificial insemination (AI), still pregnancy per AI is reduced and the risk of pregnancy loss increased. Many risk factors exist for extended postpartum anovulatory periods such as negative nutrient balance and diseases, and these risk factors are also known to depress fertility by themselves. A key feature in anovular cows when inseminated is that they develop the ovulatory follicle under subluteal or low concentrations of progesterone. Progesterone from the corpus luteum is pivotal for follicle development, oocyte competence, embryo growth, and endometrial function; however, many of these effects exerted by progesterone are mediated either by secretion of gonadotropins influencing follicular function and oocyte competence or by endometrial histotroph secretion influencing embryo/conceptus growth and developmental biology (AU)
Assuntos
Animais , Feminino , Bovinos , Infertilidade Feminina/classificação , Infertilidade Feminina/complicações , Infertilidade Feminina/diagnóstico , Bovinos/embriologia , Ovulação , ProgesteronaRESUMO
The objective was to evaluate the individual and combined effect of anovulation and cytological endometritis (CTE) on the reproductive performance of dairy cows. A total of 1,569 cows from 3 data sets were used. In data set 1, 403 Holstein cows from 5 dairies in New York were used. In data set 2, 750 Holstein cows from 2 dairies, one in Florida and one in California were used. In data set 3, 416 dairy cows, 165 Holsteins, 36 Jerseys, and 215 Holstein-Jersey crossbreeds from a grazing dairy in Florida were used. Cyclicity and CTE was determined at 35±3 (data set 2) or 49±3 d in milk (data sets 1 and 3). A variable (VarCycCTE) containing all 4 possible permutations between cyclicity (cyclic = Cyc; anovular = Anov) and CTE (present = CTE; absent = Healthy) was created. In the combined data set (sets 1, 2, and 3), pregnancy per artificial insemination (P/AI) diagnosed at 30 to 38 d after first AI was affected by VarCycCTE, with AnovCTE cows having decreased P/AI compared with CycHealthy cows (21.3 vs. 46.7%), whereas AnovHealthy (37.9%) and CycCTE cows (36.0%) had intermediate P/AI. Pregnancy per artificial insemination for the individual data sets and for pregnancy diagnosed at 63 to 74 d after artificial insemination followed a similar pattern. Pregnancy loss was not affected by VarCycCTE. Hazard of pregnancy up to 300 d in milk was affected by VarCycCTE in the combined data sets 1 and 2, with AnovCTE [hazard ratio (HR)=0.55], AnovHealthy cows (HR=0.71), and CycCTE (HR=0.8) having decreased hazard of pregnancy compared with CycHealthy cows. Median days open were 200, 159, 145, and 121 for AnovCTE, AnovHealthy, CycCTE, and CycHealthy, respectively. Hazard of pregnancy for the individual data sets followed a similar pattern. In summary, both anovulation and CTE were negatively associated with reproductive performance and, when combined, they had an additive negative effect.
Assuntos
Anovulação/veterinária , Doenças dos Bovinos/fisiopatologia , Bovinos , Endometrite/veterinária , Reprodução , Animais , California , Dieta/veterinária , Feminino , Florida , Abrigo para Animais , Inseminação Artificial/veterinária , Leite , New York , Gravidez , Estudos RetrospectivosRESUMO
[...] A wealth of information in the scientific literature is available linking diseases with depressed reproduction in dairy cows. Unfortunately, only few studies have established a causal relationship between a specific disease and fertility, and little is known about the mechanisms that underlie the decrease in pregnancy in dairy cows that had disease in early lactation. It is clear that dairy cows that suffer from disease processes have impaired resumption of postpartum ovulation, compromised fertilization and pre-and peri-implantation conceptus development, altered conceptus gene expression, increased pregnancy loss and, ultimately reduced pregnancy per insemination that causes an extension in time to pregnancy. Because mechanisms are poorly understood, no target intervention is available at this time to reverse the poor reproduction in cows that develop periparturient diseases, except methods to induce cyclicity in anovular cows or to improve insemination rate in cows not detected in estrus. Regardless of a better understanding of the underlying biology of poor fertility in diseased cows, a pivotal approach is to implement strategies that mitigate the risk factors that predispose cows to disease. Such interventions include, but are not limited to, improving transition cow management and grouping, proper dietary formulation to prevent periparturient diseases associated with intermediary and mineral metabolism, strategies for reducing calving-related disorders, and methods to prevent mastitis and lameness. Future developments in target strategies to improve reproduction of cows suffering from peripartum diseases will require a better understanding of the impaired biological processes that compromise establishment and maintenance of pregnancy in this subfertile population of cows. (AU)
Assuntos
Animais , Feminino , Bovinos , Reprodução , Complicações na Gravidez/veterinária , Período Pós-Parto , Doenças dos Bovinos/prevenção & controle , Nível de SaúdeRESUMO
[...] A wealth of information in the scientific literature is available linking diseases with depressed reproduction in dairy cows. Unfortunately, only few studies have established a causal relationship between a specific disease and fertility, and little is known about the mechanisms that underlie the decrease in pregnancy in dairy cows that had disease in early lactation. It is clear that dairy cows that suffer from disease processes have impaired resumption of postpartum ovulation, compromised fertilization and pre-and peri-implantation conceptus development, altered conceptus gene expression, increased pregnancy loss and, ultimately reduced pregnancy per insemination that causes an extension in time to pregnancy. Because mechanisms are poorly understood, no target intervention is available at this time to reverse the poor reproduction in cows that develop periparturient diseases, except methods to induce cyclicity in anovular cows or to improve insemination rate in cows not detected in estrus. Regardless of a better understanding of the underlying biology of poor fertility in diseased cows, a pivotal approach is to implement strategies that mitigate the risk factors that predispose cows to disease. Such interventions include, but are not limited to, improving transition cow management and grouping, proper dietary formulation to prevent periparturient diseases associated with intermediary and mineral metabolism, strategies for reducing calving-related disorders, and methods to prevent mastitis and lameness. Future developments in target strategies to improve reproduction of cows suffering from peripartum diseases will require a better understanding of the impaired biological processes that compromise establishment and maintenance of pregnancy in this subfertile population of cows.
Assuntos
Feminino , Animais , Bovinos , Complicações na Gravidez/veterinária , Período Pós-Parto , Reprodução , Doenças dos Bovinos/prevenção & controle , Nível de SaúdeRESUMO
Re-suspension of frozen-thawed ram sperm with ovine and bovine whole seminal plasma (SP) is beneficial for its post-thawing viability. However, neither the influence of SP incubation duration nor the re-suspension with equine SP has been tested. In the first experiment, frozen-thawed ram sperm were incubated with SP from bovine (BSP), equine (ESP) or ovine (OSP) or without SP (-SP) for short (5 min) or long (6 h) periods. Viability parameters such as sperm progressive motility, percentage of live cells and membrane functionality were assessed every 2 h for 6 h. All SP treatments showed higher spermatozoa viability than the -SP treatment in most evaluations. Incubation time did not affect sperm viability for BSP treatment, however, ESP and OSP induced a transitory benefic effect in the short incubation period and detrimental effect in the longer period. In the second experiment, frozen-thawed sperm, with or without short incubation with SP, were selected by swim-up, and their DNA fragmentation rate was assessed using comet assay immediately after swim-up completion and after 5 h of incubation. BSP, ESP and OSP protein profiles were determined by SDS-PAGE. Only ESP was associated with sperm DNA stabilization capacity and SP from rams and bulls showed protein profiles different from that of stallions. These experiments indicate that equine or ovine, but not bovine whole SP supplementation to post-thawing incubation medium of frozen-thawed ram sperm affects its viability in a time dependent manner. The beneficial effect of ESP on stabilizing DNA integrity, even after sperm washing with swim-up method and incubation for 5 h, can be determined by SPP or by antioxidant components from SP.(AU)
Assuntos
Animais , Sêmen/citologia , Espermatozoides/citologia , Criopreservação , Cavalos/classificação , OvinosRESUMO
Re-suspension of frozen-thawed ram sperm with ovine and bovine whole seminal plasma (SP) is beneficial for its post-thawing viability. However, neither the influence of SP incubation duration nor the re-suspension with equine SP has been tested. In the first experiment, frozen-thawed ram sperm were incubated with SP from bovine (BSP), equine (ESP) or ovine (OSP) or without SP (-SP) for short (5 min) or long (6 h) periods. Viability parameters such as sperm progressive motility, percentage of live cells and membrane functionality were assessed every 2 h for 6 h. All SP treatments showed higher spermatozoa viability than the -SP treatment in most evaluations. Incubation time did not affect sperm viability for BSP treatment, however, ESP and OSP induced a transitory benefic effect in the short incubation period and detrimental effect in the longer period. In the second experiment, frozen-thawed sperm, with or without short incubation with SP, were selected by swim-up, and their DNA fragmentation rate was assessed using comet assay immediately after swim-up completion and after 5 h of incubation. BSP, ESP and OSP protein profiles were determined by SDS-PAGE. Only ESP was associated with sperm DNA stabilization capacity and SP from rams and bulls showed protein profiles different from that of stallions. These experiments indicate that equine or ovine, but not bovine whole SP supplementation to post-thawing incubation medium of frozen-thawed ram sperm affects its viability in a time dependent manner. The beneficial effect of ESP on stabilizing DNA integrity, even after sperm washing with swim-up method and incubation for 5 h, can be determined by SPP or by antioxidant components from SP.