ABSTRACT: In Brazil, urea is the most used nitrogen (N) fertilizer to improve forage production. However, their excessive use can cause environmental impacts through N losses, such as ammonia (NH3) volatilization. Therefore, the current study adjusted and estimated the NH3 volatilization from urea applied on tropical pastures in three rainfall conditions using mathematical models. Data were collected from Marandu grass (Brachiaria brizantha) fertilized with 50 kg N ha-1 during wet, intermediate, and dry conditions. Ammonia volatilization was measured in five semi-open chambers for 21 days. The linear, quadratic, exponential, Gompertz, Groot, and Richards models were tested for fitting and estimating the NH3 volatilization. The Gompertz, Groot, and Richards models generated predictions similar to the observed data, with a high determination coefficient, indicating a better fit of these equations to data, with precision and accuracy. However, the Groot model was selected due to the lowest root mean square error of prediction (0.29 % total N lost as NH3). The greatest N loss as NH3 volatilization occurred in the wet, followed by intermediate and dry conditions (20.2, 17.0, and 11.3 % total N lost as NH3, respectively). Therefore, nitrogen losses as NH3 volatilization after application of 50 kg N ha-1, as urea source, are altered according to the weather conditions, reaching 20% of N added in the wet rainfall period. The Groot model is recommended for fitting and estimating the NH3 volatilization from urea applied on Marandu grass pastures in the wet and dry rainfall conditions.

RESUMO: No Brasil, a ureia é o fertilizante nitrogenado mais utilizado para melhorar a produção de forragem. No entanto, seu uso excessivo pode causar impactos ambientais por meio de perdas de nitrogênio (N), como a volatilização da amônia (NH3). Portanto, o objetivo do presente estudo foi ajustar a volatilização de NH3 da ureia aplicada em pastos tropicais em três condições de chuva utilizando modelos matemáticos. Dados foram coletados de pastos de capim-marandu (Brachiaria brizantha) adubado com 50 kg N ha-1 em condições úmidas, intermediárias e secas. A volatilização da NH3 foi medida em cinco câmaras semiabertas durante 21 dias. Os modelos, linear, quadrático, exponencial, Gompertz, Groot e Richards foram testados para ajuste e estimativa da volatilização do NH3. Os modelos de Gompertz, Groot e Richards geraram predições semelhantes aos dados observados, com alto coeficiente de determinação, indicando um melhor ajuste dessas equações aos dados, com acurácia e precisão. No entanto, o modelo Groot foi selecionado devido ao menor erro quadrático médio das predições (0,29% de N total perdido como NH3). A maior volatilização de NH3 ocorreu em condições climáticas úmida, seguido por intermediária e seca (20,2; 17,0 e 11,3% de N total perdido como NH3, respectivamente). Portanto, as perdas de N como volatilização de NH3 após a aplicação de 50 kg N ha-1, como fonte de ureia, são alteradas de acordo com as condições climáticas, atingindo a 20% do N adicionado nas condições úmidas. O modelo Groot é recomendado para ajuste e estimativa da volatilização de NH3 da ureia aplicada em pastos de capim Marandu em condições úmidas e secas.

Resumen El pasto Panicum maximum cv. BRS Tamani es una planta forrajera híbrida de alta calidad, de tamaño pequeño y con intensa actividad de macollaje. Este estudio se llevó a cabo para examinar el potencial del pasto Panicum maximum cv. BRS Tamani en diferentes edades de rebrote (49, 63, 77 y 91 días) para la producción de heno, en el período lluvioso. El experimento se realizó en la Escuela Agrícola de la Universidad Federal de Mato Grosso do Sul-Brasil, entre octubre de 2015 y abril de 2016. Los tratamientos correspondieron a cuatro edades de rebrote, con cuatro repeticiones, distribuidas en parcelas de 9 m2. Las edades de rebrote influyeron en las características morfogenéticas del pasto, excepto por la senescencia de la hoja y la longitud final de la hoja. Los rendimientos de materia verde (9.6-17.6 t ha-1) y seca (2.6-5.9 t ha-1), el rendimiento de heno (3.4-6.9 t ha-1) y las proporciones de tallo (91.6-455.9 g kg-1) y material senescente (34.8-98.4 g kg-1) aumentaron con las edades de rebrote, mientras que la proporción de hojas (837.7-402.1 g kg-1) y la relación hoja:tallo (15.9-0.9) disminuyeron (P<0.05). Los contenidos de materia seca (881.7-852.8 g kg-1) y de proteína (81.2-47.6 g kg-1) del heno disminuyeron con las mayores edades de rebrote; sin embargo, los contenidos de fibra detergente neutro (746.5-759.2 g kg-1), fibra detergente ácido (519.8-567.7 g kg-1) y lignina (74.3-86.4 g kg-1) aumentaron a medida que lo hicieron las edades de rebrote. La digestibilidad de los nutrientes disminuyó con las edades de rebrote (P<0.05). Panicum maximum cv. BRS Tamani tiene el potencial de producir heno ha-1, mejor valor nutritivo y una alta proporción de hojas en el intervalo de rebrote de 49 a 63 días.

Abstract The grass Panicum maximum cv. BRS Tamani is a hybrid high-quality, small-sized forage plant with intense tillering activity. This study was carried out to examine the potential of the grass Panicum maximum cv. BRS Tamani at different regrowth ages (49, 63, 77, and 91 d) for hay production, in the rainy period. The experiment was conducted at the Farm School of the Federal University of Mato Grosso do Sul-Brazil, between October 2015 and April 2016. The treatments corresponded to four regrowth ages, with four replicates, distributed into 9 m2 plots. Regrowth ages influenced the morphogenetic characteristics of the grass, except for leaf senescence and final leaf length. Green (9.6-17.6 t ha-1) and dry-matter (2.6-5.9 t ha-1) yields, hay yield (3.4-6.9 t ha-1), and proportions of stem (91.6-455.9 g kg-1) and senescent material (34.8-98.4 g kg-1) increased with the regrowth ages, while the proportion of leaves (837.7-402.1 g kg-1) and the leaf: stem ratio (15.9-0.9) decreased (P<0.05). The dry matter (881.7-852.8 g kg-1) and protein contents (81.2-47.6 g kg-1) of the hay decreased with the higher regrowth ages; however, the neutral detergent fibre (746.5-759.2 g kg-1) acid detergent fibre (519.8-567.7 g kg-1) and lignin (74.3-86.4 g kg-1) contents rose as the regrowth ages did. Nutrient digestibility decreased with the regrowth ages (P<0.05). Panicum maximum cv. BRS Tamani has the potential to produce of hay ha-1, better nutritive value and a high proportion of leaves in the regrowth interval of 49 to 63 d.

ABSTRACT The effects of diets containing oilseeds were measured to evaluate the productive and economic parameters in the finishing of young, feedlot Nellore bulls. Twenty-four young Nellore bulls were used, with an initial body weight (BW) of 311.46±0.37 kg and 24 months of age, distributed into individual stalls ( 4 × 20 m) in a completely randomized design, totaling four treatments with six repetitions per treatment. Four diets (control, based on corn and soybean meal, and three diets containing cottonseed, soybean, and sunflower) were evaluated. Feed and orts were measured daily to calculate intake and costs. The dry matter intake of the control group was higher than soybean (10.64 kg/day), cotton (9.88 kg/day), and sunflower (9.30 kg/day) treatments, respectively. The cottonseed treatment showed the highest average neutral detergent fiber intake. There was a dietary effect of diets on average daily gain, total weight gain, and final weight. The soybean treatment showed the highest performance, total gain (232.55 kg), and final weight (544.38 kg). Oilseed intake can modify the fatty acids profile in the meat, decreasing its saturated fatty acid content. Whole soybean seed favors performance, improves feed efficiency, fatty acid profile, and fat distribution in the carcass, and can reduce production costs.

Abstract This study was carried out to evaluate the time for the establishment of tropical forage grasses in the “Cerrado” biome, based on morphogenetic and structural traits. Three Brachiaria brizantha (Syn. Urochloa brizantha) cultivars (Paiaguás, Ipyporã and Marandu) and two Panicum maximum (Syn. Megathyrsus maximus) cultivars (Quênia and Tamani) were distributed in a randomized-block design with four replicates. Morphogenetic and structural traits of the pasture were assessed from d 35 to d 65 after sowing, at seven-day interval. Canopy height rose linearly with the establishment period, in all cultivars. In the Megathyrsus cultivars, tiller density decreased as the experimental period progressed, whereas the number of tillers in the Urochloa cultivars increased. The cultivars Ipyporã and Marandu had the highest leaf appearance rates. The lowest leaf elongation rates occurred in the cultivars Paiaguás, Ipyporã and Tamani, and the highest elongation rates in cv. Quênia. As a result, cv. Quênia showed the highest values of final leaf length (64.9 cm) and leaf blade mass (3,352.9 kg DM ha-1). The higher senescence rate of cv. Tamani (2.1 cm tiller-1 d-1) resulted in the highest percentage of dead material (1,815.5 kg ha-1) being found in the herbage mass of this cultivar. Cultivars Paiaguás, Marandu and Tamani were established at 44 d, whereas cv. Quênia and Ipyporã were established at 51 and 58 d after sowing, respectively, in the Brazilian Cerrado.

Resumen Este estudio se llevó a cabo para evaluar el tiempo para el establecimiento de gramíneas forrajeras tropicales en el bioma del “Cerrado”, con base en rasgos morfogenéticos y estructurales. Se distribuyeron tres cultivares (Paiaguás, Ipyporã y Marandu) de Brachiaria brizantha (Sin. Urochloa brizantha) y dos cultivares (Quênia y Tamani) de Panicum maximum (Sin. Megathyrsus maximus) en un diseño de bloques al azar con cuatro repeticiones. Los rasgos morfogenéticos y estructurales del pasto se evaluaron desde el día 35 hasta el día 65 después de la siembra, a intervalos de siete días. La altura del dosel aumentó linealmente con el período de establecimiento, en todos los cultivares. En los cultivares de Megathyrsus, la densidad de macollos disminuyó a medida que avanzaba el período experimental, mientras que el número de macollos en los cultivares de Urochloa aumentó. Los cultivares Ipyporã y Marandu tuvieron las tasas más altas de aparición foliar. Las tasas de elongación foliar más bajas se presentaron en los cultivares Paiaguás, Ipyporã y Tamani, y las tasas de elongación más altas en el cv. Quênia. Como resultado, el cv. Quênia mostró los valores más altos de longitud foliar final (64.9 cm) y masa de lámina foliar (3,352.9 kg MS ha-1). La mayor tasa de senescencia del cv. Tamani (2.1 cm macollo-1 d-1) dio como resultado que el mayor porcentaje de material muerto (1,815.5 kg ha-1) se encontrara en la masa de forraje de este cultivar. Los cultivares Paiaguás, Marandu y Tamani se establecieron a los 44 d, mientras que los cv. Quênia e Ipyporã se establecieron a los 51 y 58 días después de la siembra, respectivamente, en el Cerrado brasileño.

Abstract Our hypothesis was that different sources of unsaturated fatty acids from oilseeds (sunflower, soybeans, and cottonseed) could alter milk yield, fatty acid profile, and the amount of unsaturated fatty acids yielded in milk. It aimed to evaluate the effects of lipid sources on yield and composition and fatty acids in milk of primiparous Girolando cows. Five cows in lactation (35 ± 8 days), with 410 ± 7.15 kg BW were randomly distributed in a 5 x 5 Latin square. Five experimental diets, namely a control diet without an additional source of lipid and four diets with different lipid sources: cottonseed, sunflower seed, whole soybean, or soybean oil, as lipid source, to reach 70 g/kg of ethereal extract dry matter basis were used. Cottonseed and soybean oil addition reduced daily yield by 15 and 22%. Oilseed can alter fatty acid profile in milk. Whole soybean provided greater daily milk and fatty acids yields.

Resumen Se planteó la hipótesis de que es posible que el inóculo de diferentes especies de rumiantes con capacidades digestivas diferentes que se alimentan de un determinado forraje puede mostrar diferentes utilizaciones de alimento en comparación con otras especies de rumiantes. Se evaluaron cinco gramíneas Brachiaria: B. decumbens cv. Basilisk, B. decumbens acceso D70, B. humidicola cv. Tupi, B. humidicola cv. Común, y B. ruziziensis acceso R124, en dos edades de rebrote (21 y 42 d). Se analizó la producción, el contenido bromatológico, la digestibilidad de materia seca in vitro (DMSiv) y la digestibilidad de la fibra detergente neutro in vitro (DFDNiv) utilizando inóculos bovinos u ovinos. El experimento utilizó un diseño factorial de 5 × 2 × 2 y encontró efectos significativos para la variedad de gramínea y la edad de rebrote. Además, se encontraron interacciones significativas de gramínea × edad en la materia seca, la proteína cruda, la fibra detergente neutro y la fibra detergente ácido de la muestra total y lamina de la hoja. Hubo un efecto significativo de la variedad de gramínea y la edad de la gramínea en la masa del forraje, la relación lámina de la hoja/tallo, lámina de la hoja, tallo, material senescente y crecimiento. En los ensayos de la digestibilidad in vitro, el origen del inóculo mostró un efecto significativo en algunas variedades. Debido a las diferencias en los ensayos in vitro, se recomendó el uso de inóculos específicos de las especies para las evaluaciones de alimentos según el animal al que se destina. Asimismo, B. decumbens cv. Basilisk presentó la mejor digestibilidad in vitro (DMSiv y DFDNiv) en inóculo bovino, mientras que B. humidicola cv. Tupi tuvo mejor digestibilidad in vitro (DMSiv y DFDNiv) en inóculo ovino.

Abstract It was hypothesized that it is possible that inoculum from different ruminant species with different digestive abilities feeding from a certain forage may show different feed utilizations comparing to other ruminant species. Five Brachiaria grasses were evaluated: B. decumbens cv. Basilisk, B. decumbens access D70, B. humidicola cv. Tupi, B. humidicola cv. Common, and B. ruziziensis access R124, at two regrowth ages (21 and 42 d). Production, bromatological content, in vitro dry matter digestibility (ivDMD) and in vitro neutral detergent fiber digestibility (ivNDFD) were analyzed using bovine or ovine inoculums. The experiment used a 5 × 2 × 2 factorial design and found significant effects for grass variety and regrowth age. In addition, significant interactions from grass × age on dry matter, crude protein, neutral detergent fiber and acid detergent fiber of total sample and leaf blade were found. There were significant effect of grass variety and grass age on forage mass, leaf blade/stem ratio, leaf blade, stem, senescent material and growth. In vitro digestibility assays of inoculum source showed significant effect in some varieties. Due to differences in in vitro assays, it was recommended the use of species-specific inoculums for feed evaluations according to the animal it is intended for. Also, B. decumbens cv. Basilisk presented the best in vitro digestibility (ivDMD and ivNDFD) in bovine inoculum, whereas B. humidicola cv. Tupi had better in vitro digestibility (ivDMD and ivNDFD) in ovine inoculum.

RESUMO Objetivou-se avaliar o efeito de dois teores de proteína bruta no suplemento mineralnitrogenado para terminação de novilhos Nelore. Foram utilizados 90 animais, com peso médio inicial de 382,35±32,95 kg, submetidos a dois tratamentos: suplemento com 30% de proteína bruta (75% de milho, 8,91% ureia e 16,09% mineral) e 40% de proteína bruta (66,67% de milho, 11,90 % ureia e 21,43% mineral). Os animais foram mantidos em dois piquetes de Uruchloa brizantha cv. MG-5 (sin. Brachiaria brizantha). Foram realizadas pesagens ao início, aos 45 e aos 94 dias de experimento, quando foram abatidos com 451,1±35,38 kg. Foi avaliado o consumo de suplemento, o ganho de peso e variáveis econômicas. Houve efeito do tratamento sobre o consumo de suplemento (P<0,05), com médias de 0,69±0,21 (40% PB) e 2,26±0,52 (30% PB) kg/dia. A média de ganho de peso total foi superior (P<0,01) para os animais que receberam suplemento com 30 % PB (71,46 vs 64,33 kg/animal). Foi obtido maior peso de abate nos animais do tratamento com 30% PB (456,66 vs. 443,84 kg). Em ambos tratamentos, o desempenho e as caracteristicas de carcaça foram satisfatórios. Sob o ponto de vista econômico, recomenda-se a suplementação com 40 % PB na terminação de novilhos em pastagens, porém o sucesso para redução dos custos de produção no campo depende das variações entre as cotações nas diferentes regiões do país e mercado de oportunidades.

SUMMARY The objective of this study was to evaluate the effects of two protein levels in mineral-protein-energy supplements on the productivity and economic performance of Nellore steers. Ninety animals weighing 382.35±32.95 kg on average, were treated with mineral-nitrogen supplements containing 30% crude proteins (CP; 75% ground maize, 8.91 % urea and 16.09% mineral) and 40% CP (66.67 % ground maize, 11.90% urea, and 21.43% mineral). The animals were housed in two paddocks of Uruchloa brizantha ‘MG-5’ (syn. Brachiaria brizantha) and were weighed at the beginning, at 45 days, and at 94 days of the experiment, when they were slaughtered at an average weight of 451±35.38 kg. We evaluated supplement intake, weight gain and economic aspects. The 40 and 30% CP treatments significantly affected supplement intake (P<0.05), with averages of 0.69 and 2.26 kg/day, respectively. The average total weight gain was higher (P<0.01) in animals receiving the supplement containing 30 % CP (71.46 kg / animal) than in animals receiving 40% CP (64.33 kg/animal). Greater slaughter weight was attained in the animals treated with 30% CP (456.66 vs. 443.84 kg). The mineral-nitrogen supplementation in both CP levels provided satisfactory animal performance and carcass characteristics. Owing to economic considerations, it is recommended to use 40% CP mineral-nitrogen supplements on finishing steers on pasture, although success in reducing production costs of livestock ultimately depends on the variations in prices between the different regions of the country and market opportunities.

Resumo: Tradicionalmente, a contabilidade faz o rateio dos custos indiretos na atividade pecuária bovina de ciclo completo com base no custo unitário por animal (cabeça). Por esse critério, o valor de custo atribuído a um bezerro é o mesmo para um animal adulto (vaca), o que sugere não ser o critério mais adequado. O uso de insumos agropecuários, o consumo de alimentos e a compra e venda de animais ocorrem em função do peso corporal. Desenvolver um critério de rateio que permite distribuir os custos de produção ao rebanho levando em conta o peso corporal seria o mais adequado. Propor o rateio dos custos indiretos da atividade da pecuária bovina de ciclo completo com base na Unidade Animal (U.A.) é o objetivo deste trabalho, uma vez que ela permite classificar bovinos de diversas idades e sexo em uma mesma base de avaliação. Os resultados confirmaram diferenças entre os critérios de rateio, apontando que o em U.A., é o mais adequado para rateio dos custos na pecuária bovina de ciclo completo.

Abstract: Traditionally, accounting makes the apportionment of indirect costs in the full cycle beef cattle activity based on the unit cost per animal (head). By this criterion, the cost value attributed to a calf is the same for an adult animal (cow), which suggests not be most appropriate criterion. The use of agricultural inputs, food consumption and the purchase and sale of animals occur according to body weight. Provide an apportionment criterion that allows distribution of the production costs to the herd taking into account the body weight would be the most appropriate. Proposing the apportionment of the overhead costs of the full cycle beef cattle activity based on the animal unit (AU) is the objective of this study, since it allows classifying beef cattle of different ages and sex in the same evaluation basis. The results confirmed differences among the apportionment criteria, pointing out that the animal unit is the most appropriate for apportioning costs in full cycle beef cattle

RESUMO Objetivou-se avaliar fontes de nitrogênio não-proteico (NNP) combinadas para suplementação de novilhos Nelore na recria mantidos em pastagens diferidas. Após o deferimento de quatro piquetes de Brachiaria brizantha cv. MG4 por 60 dias (20 ha cada) 80 novilhos Nelore castrados, com peso corporal médio de 280,40±19,59kg, foram avaliados durante 120 dias. O manejo adotado foi pastejo rotacionado, com mudanças de piquetes a cada 15 dias. Foram avaliados quatro tratamentos com diferentes combinações de fontes de NNP: Ureia + Ureia extrusada + Ureia revestida; Ureia + Ureia revestida; Ureia + Ureia extrusada; Ureia extrusada. Em todos os tratamentos foram fornecidos suplemento proteico-energético-mineral ad libitum, com 30% de proteína bruta e 40% de nutrientes digestíveis totais.Quando avaliadas individualmente, as fontes de NNP apresentaram solubilidades distintas em água e solução tampão, sendo o menor valor observado para ureia revestida (P<0,05). Os animais dos tratamentos Ureia + Ureia extrusada + Ureia revestida e Ureia extrusa da apresentaram ganho médio diário superior (0,4kg/dia; P<0,05) aos animais dos tratamentos Ureia + Ureia extrusada (0,34kg/dia). Os animais do tratamento Ureia extrusada apresentaram maior ganho de carcaça (1,71 @/animal) em relação aos demais (P<0,05). A margem líquida do tratamento Ureia extrusada (R$ 158,20/animal) foi superior em 10,8%, 8,2% e 35,8% aos tratamentos Ureia + Ureia extrusada + Ureia revestida, Ureia + Ureia revestida e Ureia + Ureia extrusada, respectivamente. Recomenda-se a utilização de ureia extrusada como fonte de nitrogênio não proteico em suplementos para novilhos Nelore em pastagem diferida.

SUMMARY The objective of evaluating sources of non-protein nitrogen (NPN) combined for supplementation of Nelore steers in deferred pasture. After the deferral of four pickets of Brachiaria brizantha cv. MG4 (20 ha each) of 60 days, 80 Nellore steers, with average body weight 280.40 ± 19.59 kg, were evaluated for 120 days. The management adopted was rotational grazing, with pickets changes every 15 days. We evaluated four treatments with different combinations of NNP sources: Urea +Urea extruded + Urea coated; Urea + Urea coated; Urea + Urea extruded and Urea extruded. In all treatments were provided protein supplement-mineral energy ad libitum, with 30% of crude protein and 40% of total digestibility nutrient. When evaluated individually, the NPN sources presented different solubility in water and buffer, and lowest value observed for coated urea (P<0.05).The animals of the treatments Urea + Ureaextruded + Urea coated and Urea extruded showed average daily gain (0.4 kg/day; P<0.05) of animals treatments Urea + Urea extrudedthe animals(0.34 kg/day).The animals of the Urea extruded treatment higher carcass gain (1.71 @/animal) compared to other (P<0.05).The net margin of the Urea extruded treatment (R $ 158,20/animal) was superior in 10.8%, 8.2% and 35.8% to treatments Urea + Urea + Urea coated, Urea + Ureaextruded and Urea + Ureacoated, respectively. It is recommended to use extruded urea as source of non-protein nitrogen (NPN) in supplements of Nellore steers in deferred pasture.

RESUMO Objetivou-se avaliar a terminação de novilhos Nelore, castrados e não castrados, em confinamento recebendo dieta alto grão, por meio do consumo de nutrientes, desempenho produtivo e viabilidade econômica da dieta. Foram utilizados 180 animais da raça Nelore, distribuídos em dois tratamentos (castrados e não castrados), com 90 animais por tratamento, com peso médio inicial de 415,64kg, recebendo dieta alto grão, constituída de 85% de milho grão e 15% de núcleo mineral-proteico-energético. O período experimental foi de 63 dias, sendo 15 dias para adaptação as dietas e 48 dias de confinamento. Houve efeito significativo para os consumos de nutrientes (P<0,05), apresentando médias de consumos de matéria seca de 7,60 e 7,96kg para animais castrados e não castrados. Houve efeito para as variáveis de desempenho produtivo em função da classe sexual (castrado e não castrado). Os animais não castrados apresentaram maiores (P<0,05) peso de abate, ganho de peso, peso de carcaça quente, rendimento de carcaça e melhor conversão alimentar quando comparados aos animais castrados terminados em confinamento recebendo dieta alto grão. Os animais castrados apresentaram maior espessura de gordura que os animais não castrados, de 4,80 e 3,40mm, respectivamente. Os animais não castrados apresentaram margem de lucro/animal de R$ 256,00 e os castrados de R$ 202,80. Recomenda-se a terminação de novilhos Nelore em confinamento recebendo dieta alto grão. Os animais não castrados apresentaram maior ganho de peso e lucro no sistema de terminação em confinamento recebendo dieta alto grão.

SUMMARY This study aimed to evaluate the finishing Nellore steers castrated and no-castrated in feedlot receiving high-grain diet through the nutrients intake, productive performance and economic viability of the diet. 180 Nellore animals were divided into two treatments (castrated and no-castrated), with 90 animals per treatments, with an average initial weight of 415.64kg, receiving high-grain diet with 85% corn grain and 15% supplement mineral-protein-energy. The experimental period was 63 days with 15 days for adaptation diets and 48 days of feedlot. Was no significant effect on intake of nutrients (P<0.05), presenting a mean intake of dry matter (DM) of 7.60 and 7.96kg for castrated and no-castrated. Effects were observed for productive performance as a function of sex condition (castrated and no-castrated). The not castrated animals had higher (P<0.05) slaughter weight, total weight gain, hot carcass weight, carcass yield and better feed conversion when compared to castrated animals finished in feedlot receiving high-grain diet. Castrated animals have a higher fat thickness that animals no-castrated, 4.80 and 3.40mm, respectively. The no-castrated animals showed profit margin lucre/animal of R$ 256.00 and R$ 202.80 for castrated. Receiving the termination of Nellore steers in a feedlot is recommended high-grain diet. The no-castrated animals showed greater weight gain and profit in the feedlot finishing system receiving high-grain diet.

The objective was to evaluate the effect of weight, age and production efficiency of cows from genetic groups based on the calf weight at calving and at weaning. For a period of five years, data of 120 cows (60 Angus-Nellore (AN) and 60 Simmental-Nellore (SN)) at four to nine-years of age were evaluated. All cows were maintained on Brachiaria decumbens pastures, with two forage availability levels (high and low), distributed in a randomized-block design. The cows were placed together with Canchim bulls to generate the crossbred calves. A supplement, consisting of 200 g/kg crude protein and 820 g/kg of total digestible nutrients, was provided to the calves in creep feeding until 210 days-old (weaning). Supplement had a significant effect on the weight of the cow at calving and weaning. The average weights of the Angus-Nellore cows were 529.19 and 514.23 kg at calving and on the weaning day, respectively. These values were higher for Simmental-Nellore cows, which presented 569.60 and 542.59 kg, respectively. The male-calf weight at weaning was 254.69 kg, which was higher than the females (237.70 kg). Genetic group had no effect on weaning weight. The average weight for Canchim × Angus-Nellore calves was 243.41 kg and for Canchim × Simmental-Nellore it was 248.98 kg. Cow age affected weaning weight, promoting a linear increase of 0.804 kg in the weaning weight each year. Younger and smaller cows (Angus-Nellore) are more efficient for calf production.

The objective of this experiment was to evaluate the effects of replacing eCG with FSH or FSH/LH on the diameter of ovulatory follicles (DOF) and the pregnancy rates (PR) of lactating Bos indicus cows subjected to a synchronization of ovulation protocol and fixed-time artificial insemination (FTAI) based on progesterone, estradiol benzoate (EB), PGF2α, and estradiol cypionate (EC). On day 0, primiparous and multiparous Nellore cows (n = 329) at 68 days postpartum were body condition scored (BCS) and received a P4 implant (PRIMER 1.0 g P4) plus 2 mg EB intramuscularly (IM). At day 8, the implant was removed, and 250 μg cloprostenol were injected IM along with 0.5 mg EC. At the time of implant removal, the animals were divided into one of four treatments: cows received (G1) 1 mL of saline solution IM (Control; n = 80); (G2) 300 IU eCG IM (ECG300; n = 84); (G3) 15 mg FSH IM (Folltropin; n = 82); and (G4) 30 IU FSH/LH IM (Pluset; n = 83); all cows were subjected to FTAI 48-54 h after implant removal (day 10). Transrectal ultrasonography was performed to measure the DOF to FTAI and to estimate the pregnancy rate on day 35. A statistical analysis examined the effects of the treatment, technician, semen, BCS, calf age and parity on PR to FTAI. There was no significant difference in PR and DOF among the treatment groups (G1, 41.3%, 13.1 mm; G2, 46.4%, 14.5 mm; G3, 46.3%, 14.2 mm; and G4, 48.2%, 14.3 mm), but PR was higher in multiparous than in primiparous cows. Commercial FSH solutions (Pluset or Folltropin) do not promote increases in PR or DOF of lactating Nellore cows and are equal to eCG in promoting growth in preovulatory follicles and elevating the PR in Nellore cows with a moderate BCS subjected to a progesterone-based FTAI protocol with EC.

O trabalho foi conduzido com objetivo de avaliar dois protocolos de sincronização de cio em receptoras de embriões sobre a taxa de aproveitamento ao longo do ano, bem como os custos e as características reprodutivas dos animais sincronizados. Os tratamentos foram: T1: sincronização para transferência em tempo fixo com utilização de implantes de progesterona e estradiol, e T2: sincronização com aplicação de prostaglandina e observação de cio. Foram sincronizadas 2947 receptoras de embriões, e a taxa de aproveitamento foi de 83,24% no tratamento 1, e 60,73% no tratamento 2. Os corpos lúteos foram avaliados no dia da inovulação de embriões, obtendo-se 63,73% da ovulação no ovário direito. As taxas de aproveitamento não apresentaram diferenças entre os meses do ano (P>0,05). O protocolo em tempo fixo apresentou custo mais elevado (US$ 10,51 vs 2,03) que a utilização de prostaglandinas e observação de cio, no entanto a taxa de aproveitamento de receptoras foi maior. As taxas de aproveitamento das receptoras não variam ao longo do ano, quando atendidas as condições de nutrição e manejo adequados para receptoras de embrião bovino.

The study was conducted to evaluate two protocols for synchronization of estrus in embryo recipients on the utilization rate throughout the year, as well as costs and the reproductive characteristics of synchronized animals. The treatments were: syncronization to transfer fixed-time with the use of implants of progesterone and oestradiol, and synchronization with prostaglandin and heat detection. 2947 embryo recipients were synchronized, and the rate of utilization was 83.24% in treatments 1 and 60.73% in treatments 2. The corpus luteum were evaluated on the day of embryo transfer, yielding 63.73% of ovulation in the right ovary. The utilization rate did not differ among months. The protocol at fixed time showed higher cost (U.S. $ 10.51 vs 2.03) than the use of prostaglandins and heat detection, but the utilization rate was higher . The utilization rates of the recipients do not vary throughout the year, when observing the conditions of nutrition and appropriate management for bovine embryo recipients.

To verify the effects of energy supplementation and fat on follicular dynamics, metabolic profile and the production of oocytes, 15 young heifers (Bos taurus indicus) with an average age of 14 months and with an initial weight of 256.35 kg were assigned to two treatments according to weight and follicular population as evaluated by ultrasonography: in T1 (1.0 × M), animals received 100% of the energy requirements for maintenance; in T2 (1.7 × M), animals received 170% of the energy requirements for maintenance, achieved by the addition of 200 g of Megalac®. After a period of adaptation to the diet, the treatments, blood collection and follicular aspirations were started using a randomized design. The dry matter intake and weight gain were lower in the 1.0 × M group than in the 1.7 × M group. No differences were found in the plasma progesterone concentrations, albumin, glucose, urea or gonadotropin (FSH and LH) levels between the groups. The mean concentrations of cholesterol were higher in the 1.7 × M group. The total number of small (<4 mm) and medium follicles (4-8 mm) was not altered by the treatments, but the number of small follicles increased on days 1 and 2 of the estrous cycle, with higher values found in the 1.7 × M group. The average of the oocytes also increased (9.50±2.1 and 12.5±4.4 for the 1.0 × M and 1.7 × M groups, respectively). The rapid increase in the amount of energy offered in the diet changes the amount of follicles and oocytes available for follicular aspiration (OPU) in young heifers without changing their metabolic profile.

The objective of this study was to evaluate pregnancy rates of recipients of different breed groups (Nellore and crossbreed), as well as the effects of size and type of the corpus luteum (CL) on plasmatic concentrations of progesterone and pregnancy rates of embryo recipients. A total of 152 heifers were synchronized with progesterone implants and on the day of embryo transfer, previously obtained by superovulation and frozen in ethylene glycol, the diameter and type of the corpus luteum (cavitary and compact) was measured and blood was collected for progesterone measurement. The pregnancy rate was 44.1%, with a diameter of corpus luteum higher in recipients that became pregnant (2.03±0.41) compared with non-pregnant ones (1.86±0.34 cm). Plasmatic concentrations of progesterone did not differ between pregnant (1.50±1.05) and non-pregnant (1.31±0.91 ng/mL) animals. The type of corpus luteum did not influence the pregnancy rates. Only Angus and crossbred Marchigiana differ among themselves in pregnancy rates (33.3 and 59.2%, respectively). The pregnancy probability was affected only by CL diameter, but not by P4 plasmatic concentration. Selection of the corpus luteum size at the time of embryo transfer is an important factor to increase pregnancy rates in recipients, and compact and cavitary corpora lutea do not influence the pregnancy rates of bovine embryo recipients. Nellore recipients have pregnancy rates that are satisfactory and comparable to crossbred (Bos taurus × Bos indicus) recipients.