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Background : 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 cows 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 cows ( Bos taurus indicus ) from different reproductive categories in Western Amazonia. Materials, Methods & Results : Eight hundred thirteen animals 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 Tukey–Kramer 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 . Discussion: 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. Keywords : abortion, reproductive biotechnologies, Bos taurus indicus , pregnancy, progesterone supplementation. Descritores: aborto, biotecnologias reprodutivas, Bos taurus indicus , gestacao, suplementacao de progesterona. Titulo: Influencia da progesterona injetavel na taxa de prenhez e perda gestacional de femeas nelore de distintas categorias reprodutivas submetidas a inseminacao artificial em tempo fixo.

This study aimed to assess the productive performance and economic viability of intact, surgically castrated, and immunocastrated cattle. The experiment was completely randomized with 102 animals divided into three treatments: intact (control group), surgically castrated (group I), and immunocastrated (group II). Animal production indices, circulating testosterone levels, carcass yield and finishing, and profit generated by each method after slaughter were determined. Control group and immunocastrated animals showed a higher (p

Objetivou-se avaliar o padrão fermentativo e a bromatologia da silagem de capim- elefante cultivar Napier com as folhas de Embaúba na proporção de 50:50 aditivada com torta de semente de cupuaçu, cana-de-açúcar e fubá de milho em diferentes níveis. O experimento foi realizado em delineamento inteiramente casualizado, com quatro repetições por tratamento. Foram testados os tratamentos (0%), (5%), (10%) e (15%) dos aditivos citados. O material foi ensilado em mini-silos de tubos de PVC por 45 dias para efetivação do processo fermentativo. Foram avaliados pH, matéria seca (MS), proteína bruta (PB), fibra em detergente neutro e ácido (FDN/FDA), hemicelulose (HEM) e nutrientes digestíveis totais (NDT). O pH da torta de semente de cupuaçu e do fubá de milho estão dentro da amplitude preconizada na literatura. Os aditivos proporcionaram maior percentual de MS e PB em todos os tratamentos, testando estes dentro dos limites considerados aceitáveis para um adequado processo fermentativo. FDN e FDA aumentaram linearmente à medida que aumentou a inclusão de torta de cupuaçu e fubá, porém permaneceram abaixo do limite considerado limitante ao consumo voluntário dos ruminantes e a digestibilidade. Os aditivos adicionados na forragem de capim-elefante com folhas de Embaúba melhoraram o valor nutritivo da silagem.Palavras-chave: composição bromatológica, Cecropia paphytachua, ensilagem, Pennisetum purpureum. ELEPHANT GRASS SILAGE AND EMBAÚBA WITH ADDED ALTERNATIVE PRODUCTS IN THE WESTERN AMAZON ABSTRACT: This study aimed to evaluate the fermentative pattern and the bromatological of the Elephant grass silage cultivar Napier with the Embaúba leaf’s in the proportion of 50:50, added with of cupuassu cake seed, sugarcane and corn meal at different levels. The experiment was carried out in a completely randomized design, with four replications per treatment. The treatments 0%, 5%, 10%) and 15% of the cited additives were tested. The ensiled material was in mini-silos of PVC pipes for 45 days to affect the fermentation process. pH, dry matter (DM), crude protein (CP), neutral detergent fiber and acid (NDF/ FDA), hemicellulose (HEM) and total digestible nutrients (NDT) were evaluated. The pH of the cupuassu and maize meal are within the range recommended in the literature. The additives provided a higher percentage of DM and PB in all treatments, and these were within the limits considered acceptable for an adequate fermentation process. NDF and ADF increased linearly as the inclusion of cupuassu cake and corn meal increased, but remained below the limits considered limiting the voluntary consumption of ruminants and digestibility. The additives added in the elephant grass fodder with Embaúba leaves improved the nutritive value of the silage.Keywords: bromatological composition, Cecropia paphytachua, ensilage, Pennisetum purpureum.