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Neospora caninum is an important cause of abortions in dairy cattle, leading to severe economic losses. The objective of this study was to determine the association of serum antibodies against N. caninum with a history of abortion in dairy cows. A total of 46 dairy cows from nine dairy farms were evaluated; 28 with a history of one or more abortions and 18 without a history of abortions. Antibodies against N. caninum were detected by indirect immunofluorescence, and the reaction was considered positive when the titer was ?1:50. Serum antibodies against N. caninum were detected in 39.1% (18/46) of all cows, 57.1% (16/28) of cows with a history of abortion, and 11.1% (2/18) of cows without a history of abortion. Among the seropositive cows, 88.9% had a history of abortion. All farms showed at least one animal positive for N. caninum. These results indicate an association between seropositivity for N. caninum and a history of abortion in cows. Cows with a history of abortion were 10.6 times more likely to be seropositive for N. caninum than cows without a history of abortion. Therefore, we concluded that there is an association between a history of abortion and the presence of antibodies against N. caninum in dairy cows.

O Neospora caninum é um importante agente causador de abortos em bovinos leiteiros, promovendo severos prejuízos econômicos. Objetivou-se neste trabalho associar a presença de anticorpos contra N. caninum com histórico de abortamento em vacas leiteiras. Um total de 46 vacas leiteiras foram avaliadas, sendo 28 com histórico de um ou mais abortamentos e 18 sem histórico de abortamentos, provenientes de nove propriedades leiteiras. Para a detecção de anticorpos contra N. caninum foi realizada a reação de imunofluorescência indireta, sendo consideradas positivas quando os títulos foram maiores ou iguais a 1:50. A soro ocorrência de anticorpos contra N. caninum entre todas as vacas avaliadas foi de 39,1% (18/46), entre as vacas com histórico de abortamento foi de 57,1% (16/28) e de 11,1% (2/18) nas vacas que não haviam abortado. Dentre as vacas soropositivas, 88,9% possuíam histórico de aborto. Todas as propriedades avaliadas apresentaram animais com anticorpos contra o N. caninum. Há uma associação entre vacas soropositivas para N. caninum e histórico de abortamento. Vacas soropositivas apresentaram 10,6 vezes mais chances de serem sororreagentes ao Neospora caninum do que vacas sem histórico de abortamento. Conclui-se que existe associação entre histórico de abortamento e presença de anticorpos contra Neospora caninum em vacas leiteiras.

This study aimed to evaluate the effects of gonadorelin (GnRH), used both at the outset of a timed artificial insemination (TAI) protocol to synchronize follicular wave recruitment and at the end to synchronize ovulation, on the conception rate (CR) in Nellore cows. The experiment was conducted on two beef cattle farms in the Vale do Araguaia, MT. The body condition score (BCS) evaluation and ultrasound examination to determine ovarian status [follicle diameter < 10 mm, ? 10 mm or presence of corpus luteum (CL)] were performed at the beginning (Day 0) of the TAI protocol. Multiparous cows (n = 494) were subjected to the following protocol: Day 0 – insertion of intravaginal progesterone device (P4 DIB®, MSD) previously used for 8 or 16 days and IM administration of 2.0 mg of estradiol benzoate (EB, Gonadiol®, MSD); Day 8 – P4 device withdrawal, IM injection of 300 IU of equine chorionic gonadotropin (eCG, Folligon®, MSD), 1.0 mg of estradiol cypionate (ECP®, Zoetis) and 0.265 mg of Sodium cloprostenol (PGF2?, Ciosin®, MSD); Day 10 – TAI, performed by a single inseminator. Animals were randomly assigned to one of four groups: control (n = 126), GnRH D0 (n = 123), GnRH D10 (n = 123) and GnRH D0 + D10 (n = 122). Animals treated with GnRH received 50 mcg of gonadorelin (GnRH, Cystorelin®, Merial). Pregnancy was diagnosed by ultrasound 39 ± 10 days after TAI. Data were analyzed using the GLIMMIX procedure of SAS program (P < 0.05). The overall CR was 42.71%. Effect of treatment was not detected (P = 0.2482) on CR, which was 36.89% ± 0.19 (47/126) for the control group, 46.08% ± 0.19 (56/123) for GnRH D0, 48.30% ± 0.18 (61/123) for GnRH D10 and 38.48% ± 0.19 (47/122) for GnRH D0 + D10. An effect of farm was detected; the CR was 47.32% ± 0.13 at Farm A and was 38.24% ± 0.13 at Farm B (P = 0.0249). No effects of the interaction between farm and treatment were observed (P = 0.7662), nor of those among ovarian condition and treatment (P = 0.1225) on CR. Cows with follicles < 10 mm had lower CR (16.44% ± 0.08; P = 0.0001) than cows with follicles ? 10 mm (46.15% ± 0.07) and cows with CL (48.35% ± 0.07). It was concluded that GnRH used to both synchronize the follicular wave recruitment and synchronize ovulation as part of a TAI protocol, did not improve the conception rate in Nellore beef cows.