Influência da progesterona injetável na taxa de prenhez e perda gestacional de fêmeas nelore de distintas categorias reprodutivas submetidas a inseminação artificial em tempo fixo / Influence of injectable progesterone on the pregnancy rate and gestational loss of Nellore females of different reproductive categories undergoing fixed-time artificial insemination

Progesterone (P4) is essential for embryonic development and maintenance of pregnancy when deficiency causes early embryonic loss. In this study, we investigated the ability of hormonal supplementation to improve the fertility of Nellore females subjected to fixed-time artificial insemination (IATF) protocols. Here, we evaluated the effect of long-acting injectable progesterone (iP4) supplementation in the D4 after IATF on pregnancy rate and pregnancy loss in Nellore females (Bos taurus indicus) from different reproductive categories in Western Amazonia. Eight hundred thirteen Nellore females from 5 farms were selected and distributed into 2 groups: control [GC; administration of 0.5 mL of 0.9% saline solution, intramuscularly - IM] (n = 407) and a group that received injectable progesterone (iP4) that was long-acting [GiP4; administration of 0.5 mL of iP4, 300 mg, via IM four days after IATF] (n = 406). Each group contained 3 subgroups: heifers, primiparous cows, and multiparous cows. Of the 407 animals in the CG, 103 were heifers, 107 primiparous, and 197 multiparous. Of the 406 animals in the GiP4 group, there were 101 heifers, 107 primiparous, and 198 multiparous. On a random day of the estrous cycle (D0), an intravaginal device containing 1 g of P4 and 2 mg of estradiol benzoate (BE) was inserted by intramuscular injection. On D8, the P4 device was removed and 150 µg of D-cloprostenol (PGF2α), 300 IU eCG, and 1 mg BE were administered IM. Cows were inseminated at D10, 48-52 h after procedure on D8. Pregnancy diagnosis was made between 35 and 40 days after insemination through ultrasound examination. Between 80 and 90 days after insemination, a new ultrasound examination was performed to assess early pregnancy loss. The data were processed using the SAS 9.2. The conception rate, pregnancy loss, and final conception rate were analyzed using PROC GLIMMIX according to groups (CG and GiP4), categories (heifers, primiparous and multiparous), and their interactions as variables. The differences in the means of least squares were adjusted using the Tukey­Kramer method. Statistical significance was defined as P < 0.05. The general conception rate was 46% (375/816). Regardless of the animal class, GiP4 animals (51.97%) had higher conception rates (P < 0.05) than CG (40.29%). In the subgroups (heifers, primiparous and multiparous cows), there was a difference (P < 0.05) between animals treated with iP4 (52.48%, 57.94%, and 48.48%, respectively) and those who were not (39.81%, 41.12%, and 40.10%, respectively). Gestational losses, regardless of the animal class, were higher in females in the CG (7.93%) [P < 0.05] compared to those in the GiP4 group (2.84%). Regardless of treatment with iP4, the percentage of gestational loss in heifers was significantly higher (10.64%) than that in primiparous and multiparous cows (3.77% and 2.86%, respectively). The final conception rates were higher in animals that received long-acting iP4, which increased the final pregnancy in all parity categories. In the present study, the use of iP4 increased the pregnancy rate in Nellore females, regardless of the category. Although there has been no consensus on the use of iP4, there is an agreement that increases in the pregnancy rate are related to the moment of exogenous P4 application. In addition to influencing the pregnancy rate, reduction in pregnancy losses is also attributed to iP4 treatment, a fact demonstrated in the present study, where animals treated with iP4 had a lower pregnancy loss rate than normally occurs in beef cattle. Supplementation with long-acting iP4 increased the pregnancy rate at D35-40, reduced pregnancy losses, and increased the conception rate on D80-90 days in Nellore females reared in the Western Amazon, regardless of the animal category.(AU)

Reproductive toxicity of Samanea tubulosa on rats / Toxicidade reprodutiva de Samanea tubulosa em ratos

Samanea tubulosa is a plant used for medicinal and feeding purposes. However, ingestion of S. tubulosa pods has been associated with bovine abortion. Thus, the aim of this work was to investigate the effects of diet containing 5% of S. tubulosa pod meal on male and female Wistar rats. Diet was administered to male rats (n = 10) for 60 days before mating. Female rats (n = 10) received the treatment for 30 days, during cohabitation and from gestational day (GD) 0 to GD20. Treated animals were mated with untreated rats. In male rats, plant consumption caused decreased food consumption and 20% fertility index reduction. Litters from treated males presented lower body weight and crownrump length. Female rats treated with the plant increased water and food intake and body weight. Decreases in fertility, fecundity and gestation indices and increase of placenta weight and mean number of corpora lutea were found. Thus, owing to the possible general and reproductive toxic effects, long-term consumption of S. tubulosa is not recommended for phytotherapic or food purposes...

Samanea tubulosa é uma planta utilizada na fitoterapia e na alimentação animal. Entretanto, a ingestão de vagens de S. tubulosa tem sido associada à ocorrência de abortos em bovinos. Assim, o objetivo do trabalho foi investigar os efeitos da dieta contendo 5% de vagens de S. tubulosa em ratos machos e fêmeas Wistar. A dieta foi administrada para ratos machos (n = 10) por 60 dias antes do acasalamento. Ratos fêmeas (n = 10) receberam o tratamento por 30 dias, durante a coabitação e do dia gestacional (GD) 0 ao GD 20. As fêmeas tratadas foram acasaladas com ratos não tratados. Em machos, o consumo da planta causou diminuição no consumo de ração e redução de 20% no índice de fertilidade. A prole de machos tratados apresentou menor ganho de peso e comprimento cabeça cauda. Fêmeas tratadas com a planta apresentaram aumento do consumo de ração e água e do peso corporal. Ainda, foram observadas diminuição na fertilidade, fecundidade e no índice de gestação e aumento do peso da placenta e no número médio de corpos lúteos. Desse modo, em decorrência aos possíveis efeitos tóxicos sistêmicos e reprodutivos, o consumo prolongado de S. tubulosa não é recomendado para fins fitoterápicos ou alimentar...

Perfil sorológico dos anticorpos colostrais para Neospora caninum em bezerros livres da infecção / Serological profile of colostral antibodies to Neospora caninum in infection free calves

Neospora caninum é considerado a principal causa de aborto bovino mundial. O diagnóstico laboratorial correto é muito importante para identificar os animais infectados e para aplicar medidas de controle. O objetivo deste trabalho foi mostrar o declínio de anticorpos colostral em bezerros. Este estudo empregou oito bezerros holandeses, recém-nascidos, machos, descendentes de vacas soronegativas para N caninum. Amostra de sangue pré-colostral foram colhidas destes bezerros e todos estavam soronegativos pra N. caninum. Estes bezerros foram alimentados com dois litros de um pool de colostro de vacas soropositivas dentro de duas horas após o nascimento. Amostras de sangue dos bezerros foram colhidas semanalmente até os animais soroconverterem negativo. As amostras foram testadas para anticorpos de N. caninum usando teste de imunofluorescência indireta nos títulos de 1:50; 1: 100 e 1:200. Os resultados mostraram que 3 dos 8 bezerros não soroconverteram e foram excluídos do estudo. Os restantes cinco bezerros soroconverteram em todos os títulos no quinto dia após a inoculação. No título 1:50, um bezerro permaneceu positivo por 21 semanas, dois por 20 semanas e um por 13 semanas. No título 1:100, um bezerro foi positivo por 15 semanas e o restante quatro bezerros por 13 semanas. No título 1:200, cada bezerro foi positivo por 1; 7; 12; 12 e 13 semanas, respectivamente. Estes resultados demonstram que o anticorpo colostral para N. caninum pode permanecer até 21 semanas após o nascimento nos bezerros e é muito importante excluir os bezerros até quatro meses de idade nos estudos de soroprevalência para impedir os resultados falso-positivos.

Neospora caninum is considered the main cause of bovine abortion worldwide. The correct laboratorial diagnose is very important to identify the infected animals and to apply control measure. The objetive of this study was to show the persistence period of colostral antibodies in calves. Eight newborn Holstein Friesan calves, males, were selected from N. caninum soronegative dams. Pre-colostral blood samples were collected of these calves and all of them were seronegative to N. caninum. They were fed with two liters of pooled colostrum from seropositive cows within two hours after birth. Blood samples were collected and tested weekly until the animals turned negative. Serum samples were tested for antibodies to N. caninum using indirect fluorescence antibody test at 1:50; 1: 100 and 1:200 dilutions. Antibodies were not detected from three out of eight calves and they were excluded from the study. The remaining 5 calves seroconverted in all dilutions at the fifth day after colostrums ingestion. At 1:50 dilution, one calf remained positive for 21 weeks, two for 20 weeks and one for 13 weeks. At 1:100, one calf was positive for 15 weeks and the remaining 4 calves for 13 weeks. At 1:200, each calf was positive for 1, 7, 12, 12 and 13 weeks, respectively. These results demonstrate that the colostral antibody to N. caninum may persist until 21 weeks after birth in calves and it?s very important to exclud the calves at the first month of age in the seroprevalence studies to avoid the false-positive results.

Fate of Neospora-seropositive animals: an opinion

Neospora caninum es un protozoo que causa abortos en los bovinos produciendo importantes pérdidas económicas en todo el mundo. Existe evidencia reciente que demuestra que los bovinos infectados en forma crónica desarrollan mecanismos inmunes de protección contra el aborto causado por N. caninum. Por otro lado, la existencia de otras pérdidas económicas distintas del aborto es aún tema de controversia. Aunque la eliminación de bovinos seropositivos a la enfermedad a sido recomendado como medida de control sanitaria, un rodeo libre de infección no está exento de sufrir una exposición postnatal y "tormentas" de abortos. La utilización de una vacuna inactivada disminuye la tasa de abortos; sin embargo los anticuerpos vacunales no pueden ser diferenciados de aquellos producidos por infecciones naturales. Considerando que los anticuerpos maternos desaparecen a los 6 meses de vida, la serología de terneras de reemplazo antes del servicio y la vacunación podría ser una posible estrategia de control. Este artículo discute las estrategias de control para limitar la difusión de la neosporosis en bovinos y brinda posibles líneas de investigación.

Neospora caninum is an abortive protozoon in cattle, which causes severe economic losses worldwide. Chronically infected cattle however develop immune responses protecting against further Neospora induced abortions. Controversy about losses other than abortion in Neospora-infected cattle still exists. Although, culling of seropositive animals has been recommended as a strategy for reducing economic losses due to N. caninum, there is no guarantee of escaping postnatal infection and abortion storms by having a "Neospora-sterile herd". An inactivated vaccine has been demonstrated to reduce abortion rates. Antibodies generated by natural infection can not presently be differentiated from those induced by vaccination; however, since maternal antibodies disappear by 6 months in calves born to vaccinated heifers, a test-and cull strategy could be performed in replacement heifers before breeding and vaccination. This review article discusses control strategies for Neospora-infection in cattle, and provides suggestions for further research.

Neosporosis bovina: conceptos generales, inmunidad y perspectivas para la vacunación / Bovine neosporosis: general concepts, immunity and perspectives for vaccination

Neospora caninum es agente causal de aborto en bovinos de regiones ganaderas de todo el mundo. Su ciclo de vida es heteroxeno siendo el perro (Canis familiaris) y el coyote (Canis latrans) los hospedadores definitivos reconocidos hasta el presente. La infección transplacentaria es un eficiente mecanismo de transmisión de la enfermedad pero existe evidencia que demuestra la transmisión postnatal en los bovinos. Debido a las pérdidas económicas que causa la neosporosis, diversas técnicas diagnósticas han sido desarrolladas. La fisiopatología del aborto causado por N. caninum no ha sido completamente esclarecida. La modulación del sistema inmune por efecto de la preñez ocasiona un período de susceptibilidad al aborto por N. caninum. Aunque la resistencia al parásito ha sido asociada con una respuesta de linfocitos T tipo 1, dicha respuesta inmune es incompatible con una preñez exitosa. Sin embargo, los mecanismos inmunes presentes en animales crónicamente infectados protegen del aborto ante una segunda exposición al protozoo. La comprensión de esa respuesta inmune adquirida constituye un desafío para el desarrollo de inmunógenos. Este trabajo menciona conceptos generales de la neosporosis bovina haciendo énfasis en los mecanismos inmunes y las perspectivas para la vacunación.

Neospora caninum causes abortions in cattle worldwide. The Neospora-cycle of life is heteroxenous. Dogs (Canis familiaris) and coyotes (Canis latrans) are the definitive hosts known at present. Although, transplacental infection is an efficiently mode of transmission in cattle; there are also experimental and field data that prove horizontal transmission. Several techniques are available for diagnosis since neosporosis is recognized as a disease that causes economic losses in cattle. The mechanisms that produce the abortion are not completely understood. The immunomodulation observed during the pregnancy, is associated with a susceptible period where Neospora-abortion can occur. Resistance to the parasite is dependent on T helper cell 1 cytokine responses. This has important repercussions for pregnant female bovine because strong T helper cell 1 cytokine responses are incompatible with successful pregnancy. However, it was demonstrated that chronically infected cows develop immune mechanisms against the abortion caused by a second Neospora-exposure. The comprehension of those mechanisms is needed for the formulation of Neospora-vaccines that prevent bovine neosporosis. General concepts about neosporosis with emphasis in the immune response and perspectives for vaccination are mentioned in the present review.