ABSTRACT The objective of this study was to evaluate the reproductive performance of ewes subjected to a short-term protocol for estrus induction using 1 mg of Norgestomet during the non-breeding season in Brazil. A total of 84 ewes were randomly divided into two equal groups (n = 42 per group). Controlled Internal Drug Release (CIDR) containing 330 mg progesterone was inserted into the vagina in the first 42 ewes, and for the other 42 ewes in the second group, 1 mg of Norgestomet was placed subcutaneously in the convex surface of the ear. Implants and devices were removed in both groups on day 6. Following the removal of implants and devices, 10 mg of PGF2α and 300 IU of eCG were injected in all the ewes. After 48 h of application, three fertile rams were added to the herd. Ewes and rams were kept together for four days. Rams were removed on day 12, and after 42 days, pregnancy was diagnosed by ultrasound scanning. Short-term protocols using either an intravaginal device or ear implant were similarly effective to estrus induction (95.23 vs. 92.85%), and all ewes from both groups had estrus manifestation within 72 h after implant removal (72±9 h). In addition, no significant difference in pregnancy rate was observed between ewes treated with the intravaginal device and ear implant protocols (52.38 vs. 57.14%). These results suggest that 1 mg of Norgestomet is a good alternative for short-term protocols for estrus induction/synchronization during the non-breeding season in ewes. It is possible to replace the progesterone-releasing intravaginal device by the ear implant and obtain the same reproductive effectiveness in ewes.

RESUMO: O estudo foi conduzido para avaliar o desempenho reprodutivo de novilhas Nelore, não imunizadas para herpesvirus bovino tipo 1 (BHV-1), vírus da diarreia viral bovina (BVDV) e leptospirose bovina (LB), submetidas a diferentes protocolos vacinais em manejo de inseminação artificial em tempo fixo (IATF) e repasse com touro em monta natural. Um total de 763 animais foram distribuídos em quatro grupos: T1 - controle sem vacinação; T2 - vacinação contra LB; T3 - vacinação contra BHV-1 e BVDV T4 - vacinação com LB+ BHV-1 e BVDV. A vacinação foi iniciada 30 dias antes da IATF (D-40) com a aplicação da segunda dose em D-10. Verificou-se a taxa de ocorrência de infecção natural por LB, BHV-1 e BVDV realizando-se exames sorológicos. O diagnóstico de gestação inicial foi feito aos 30, 60 e 120 dias. Avaliou-se as taxas de prenhez em função dos grupos, do peso, escore de condição corporal, presença ou ausência de cio, inseminador, touro, ocorrência de abortos ou morte embrionária. Os resultados obtidos revelaram que soropositividade para leptospirose foi de 100% para todos os grupos, variando de 77,0% a 94,0% para BHV-1 e 64,0% a 87,0% para BVDV. O protocolo vacinal não interferiu na taxa de prenhez, de mortalidade embrionária ou fetal. Houve diferença na taxa de prenhez em relação ao peso dos animais no início da estação reprodutiva e a presença de cio no momento da IATF. Concluiu-se que o protocolo vacinal não interferiu no desempenho reprodutivo dos grupos experimentais.

ABSTRACT: This study evaluated the reproductive performance of Nellore heifers without previous vaccination undergoing fixed-time artificial insemination (FTAI) and subsequent natural breeding under different vaccination protocols against infectious bovine herpesvirus 1 (BHV-1), bovine viral diarrhea virus (BVDV), and bovine leptospirosis (BL). A total of 763 animals were included; the group assignment was as follows: T1, control without vaccination; T2, vaccination against BL; T3, vaccination against BHV-1and BVDV; T4,vaccination against combination of BL + BHV-1and BVDV. Vaccination was started 30 days before FTAI (D-40), and a booster dose was administered at D-10. Serological tests were used to verify the occurrence rate of natural infection by BL, BHV-1, and BVDV. Initial pregnancy was diagnosed at D30, D60, and D120 after FTAI. Final pregnancy rates were evaluated by group, weight, body-condition score, occurrence of estrus, inseminator, bull, and occurrence of abortions or embryonic death. In all groups, results indicated seropositivity of 100% for leptospirosis, 77.0-94.0% for BHV-1, and 64.0-87.0% for BVDV. The vaccination protocol was not a significant influencing factor of pregnancy rate and embryonic or fetal mortality; whereas, animal weight at the beginning of the breeding season and presence of estrus at FTAI were significant influencing factors of pregnancy rate. The vaccination protocol had no interference with the reproductive performance of the experimental groups.

Analisou-se taxa de prenhez (TP) e de natalidade (TN) de matrizes Nelores criadas extensivamente no Cerrado/Pantanal, acasaladas durante 4 estações de monta natural (2009 a 2012), avaliando relação com índice de temperatura e umidade (ITU) e efeito do ano da estação de monta. Utilizaram-se 2.116 informações de matrizes, pertencentes às categorias de multíparas (n = 1430), primíparas (n = 338) e nulíparas (n = 348). Nos meses de estação de monta (dezembro a fevereiro) coletaram-se informações da temperatura e umidade relativa do ar, para o cálculo de índice de temperatura e umidade (ITU). Realizaram-se análise de variância com um modelo contendo como fontes de variação os efeitos fixos de categoria e ano de estação de monta sob a TP e TN; e análise da regressão linear e correlação entre o ITU e a TP e TN. Observaram-se efeito significativo (p < 0,05) de categoria sob a TP. Classificou-se o ITU médio entre as estações de monta como moderado. O ITU das estações de monta apresentou relação alta e significativa (p < 0,05) apenas na TN das nulíparas, e baixas tendências de relação com as demais. Conclui-se que o ano da estação de monta e o ITU não apresentaram relação com desempenho das matrizes, exceto as nulíparas considerando ITU e TN.

We analyzed the pregnancy rate (PR) and birth rate (BR) of Nellore cows raised extensively in the Cerrado/Pantanal during 4 mating seasons (2009-2012), assessing the relationship with the temperature and humidity index (THI) and the effect of the year and breeding season. We used information from 2,116 cows, which were categorized as either multiparous (n = 1430), primiparous (n = 338), or nulliparous (n = 348). In the months of the breeding season (December-February), temperature and relative humidity data were collected to calculate the temperature and humidity index (THI). An ANOVA was performed with a model that included sources of variation from the fixed effects of category of cow and year on PR and BR; and a linear regression analysis and correlation between THI and PR and BR. We observed a significant effect (p < 0.05) on PR. We classified the average across breeding seasons as a moderate THI. The THI of the breeding seasons showed high and significant (p < 0.05) effects only on the nulliparous BR, and low values in other categories. It is concluded that the seasonal THI was not related to the performance of cows, except BR in nulliparous cows.