Energy values and metabolizability of lipid sources of plant and animal origin in the diet of Japanese quail

The objective of this study was to determine the energy values and metabolizability of different lipid sources in the diet of Japanese quail at the laying phase. The quail were distributed in a completely randomized design with ten replications of seven poultry per treatment, totaling six treatments: basal feed (control) and basal feed containing 10% soybean oil, corn oil, canola oil, sunflower oil, and poultry fat. The values of nitrogen-corrected apparent metabolizable energy (AMEn) and the metabolizability coefficient (MC%) were evaluated. No significant difference was found between the different lipid sources for AMEn (kcal/kg) and MC (%). The value of metabolizable energy corrected for nitrogen for soybean oil was 8,790 kcal/kg; 8,773 kcal/kg for corn oil; 8,784 kcal/kg for canola oil; 8,788 kcal/kg for sunflower oil; and 8,681 kcal/kg for poultry fat in laying Japanese quail. The digestibility coefficients were 93.88% for soybean oil, 93.53% for corn oil, 93.32% for canola oil, 93.74% for sunflower oil, and 93.06% for poultry fat.

Effects of a hepatoprotectant and different feed energy sources on milk composition and nutrient partitioning in lactating cows / Efeitos de um hepatoprotetor e diferentes fontes de energia na dieta sobre a composição do leite e a partição dos nutrientes em vacas lactantes

The present study aimed at assessing the effects of hepatoprotective agents in diets that contain sources of energy on milk production, milk composition, and nutrient partition in lactating cows. Sixteen Holstein x Gir crossbred mid-lactation cows with an average body weight of 553 ± 85 kg were used in this study. These animals were allocated in a 4x4 Latin square design. A 2x2 factorial arrangement was employed in this feeding experiment. In each treatment, cows received diets with or without a hepatoprotective agent and variable in ground corn grain or citrus pulp as energy sources. Evaluated parameters included nutrient intake and digestibility, milk production, milk composition, energy balance, and nitrogen balance. Performance and nutrient balance variables were assessed and no interaction was observed between the hepatoprotective compounds and the dietary sources of energy. Dry matter intake, milk production and net energy for lactation were higher in corn as an energy source whereas milk fat content was higher in citrus pulp diets. There was a reduction in protein and casein contents in the milk of cows that was supplemented with an hepatoprotective agent. In this study, the hepatoprotective agent improved nitrogen balance in dairy cows. The use of the hepatoprotective compounds in the diet of these lactating cows in confinement reduced the milk protein fraction and favored a higher nitrogen balance in these animals. Retention of nitrogen compounds in the metabolism of lactating cows under confinement is influenced by hepatoprotective agents.(AU)

Objetivou-se com este estudo avaliar os efeitos de fontes de energia associadas a um hepatoprotetor sobre a produção, composição do leite e a partição dos nutrientes em vacas lactantes confinadas. Foram utilizadas 16 vacas mestiças Holandês x Gir no terço médio da lactação, com peso corporal médio de 553 ± 85 kg, distribuídas em delineamento experimental quadrado latino 4x4 quádruplo em arranjo fatorial 2x2. Os tratamentos consistiram de dieta com ou sem a inclusão do hepatoprotetor, e variação de milho moído ou polpa cítrica como fontes de energia. Não houve interação (P>0.05) entre as fontes de energia e o hepatoprotetor para as variáveis de desempenho e balanço de nutrientes. O consumo de matéria seca, a produção de leite, o leite corrigido para 4% de gordura foram maiores (P<0.05) nas dietas com milho moído como fonte de energia. O teor de gordura do leite foi maior (P<0.05) nas dietas com a polpa cítrica. Houve redução (P<0.05) no teor de proteína bruta e caseína no leite das vacas que receberam o hepatoprotetor na dieta. O hepatoprotetor favoreceu maior (P<0.05) retenção e balanço de nitrogênio nas vacas. Portanto, o milho moído pode ser utilizado na dieta como fonte de energia para impulsionar a produção de leite. Enquanto, a fonte de energia proveniente da polpa cítrica afeta a composição do leite, através do incremento no teor de gordura. O uso de hepatoprotetores na dieta favoreceu maior retenção de nitrogênio em vacas lactantes confinadas.(AU)

Vegetable lipid sources in the diet of japanese quails in the rearing phase and effects on the initial phase of production / Fontes lipídicas vegetais na alimentação de codornas japonesas em fase de recria e sua repercussão na fase inicial de produção

This study aims to evaluate the residual effect of different lipid sources in the diet of Japanese quails (Coturnix japonica) in the rearing phase on the performance and egg quality in the initial phase of egg-laying. In the first stage, 400 Japanese quails aged 21 days were used, being distributed in a completely randomized experimental design, with five treatments and ten replicates of eight birds/replicate Treatments consisted of basal ration (BR) with 2.5% soybean oil; BR with 2.5% corn oil; BR with 2.5% cottonseed oil; BR with 2.5% sunflower oil; and BR with 2.5% canola oil.At 42 days, maintaining the initial design, all quails received a basal ration with soybean oil, in order to evaluate the residual effect of the previous phase on the performance and egg quality in the initial phase of egg-laying (43 - 84 days). The different lipid sources did not affect the performance of quails in the initial phase of production. For egg quality, yolk height, yolk diameter, yolk index, gravity, and Haugh unit (HU) showed better results in the treatment using sunflower oil. There was a residual effect of the use of lipid sources of vegetable origin in the rearing phase diet of Japanese quails on egg quality traits. Lipid sources from soybean, corn, cottonseed, canola, and sunflower seeds can be used as energy sources in the rearing diet of egg-laying quails for not being harmful to their initial performance. The longevity in egg production of quails fed with different lipid sources in the rearing phase was similar.

A pesquisa foi conduzida com objetivo de avaliar o efeito residual de diferentes fontes lipídicas na dieta de codornas japonesas (Coturnix japonica) na fase de recria sob o desempenho e a qualidade de ovos na fase inicial de postura. Na primeira etapa foram utilizadas 400 codornas japonesas com idade de 21 dias, as aves foram distribuídas em tratamentos seguindo um delineamento inteiramente casualizado com dez repetições, de oito aves, em cinco tratamentos: ração basal (RB) com 2,5% de óleo de soja, RB com 2,5 % de óleo de milho, RB com 2,5% de óleo algodão, RB com 2,5% de óleo de girassol e RB com 2,5% de óleo de canola. Aos 42 dias mantendo o delineamento inicial, todas aves receberam ração basal com óleo de soja, para que fosse avaliado o efeito residual da fase anterior sobre o desempenho e a qualidade dos ovos na fase inicial de postura (43 - 84 dias). As diferentes fontes lipídicas não afetaram o desempenho das aves na fase inicial de produção. Para a qualidade dos ovos, os parâmetros de altura, diâmetro e índice de gema, gravidade e UH foram melhores no tratamento com utilização de óleo de girassol. Houve efeito residual da utilização de fontes lipídicas de origem vegetal na dieta em fase de recria de codornas japonesas sobre as características da qualidade dos ovos. As fontes lipídicas oriundas das sementes de soja, milho, algodão, canola e girassol podem ser utilizadas como ingredientes energéticos na dieta de recria de codornas poedeiras por não serem prejudiciais ao desempenho inicial das aves. A longevidade na produção dos ovos das aves alimentadas com diferentes fontes lipídicas na fase de recria foi semelhante.

Physical and environmental characteristics of the compost barn system and its effects on the physical integrity, reproduction and milk production of dairy cattle: a scoping review

Compost barn (CB), although recent in Brazil, is increasingly gaining popularity among the intensive breeding systems in the dairy sector. This system promises to offer several advantages to producers and animals: such as providing an environment in which milk production is increased and the physical integrity of cattle is improved, reducing mastitis episodes, and promoting thermal comfort for animals. Another factor that highlights CB concerning other intensive systems is the composting process, generated by the deposition of carbon-rich materials (bedding) with nitrogen sources (urine and feces) from animals. For the full benefits of this composting to be achieved, management, especially of bedding, must be carried out correctly, considering the development requirements of the compost, the use of quality organic material, adequate ventilation, and an ideal rate of animal capacity, so that the generation of heat occurs efficiently. However, there is a general lack of information about the CB system. Hence, there is an increasing need for data surveys of Brazilian regions to compare the diversity of materials used in bedding, assessing energy efficiency and performance over time. Therefore, this bibliographical review addressed the main points of the CB system approach, considering that studies such as this are consistently relevant for rural producers, facilitating decisions regarding the implementation and management of the CB system on their farms.

Protein and energy for maintenance and gain of European quail fed different energy sources and housed at two temperatures

The objective of this study was to evaluate whether replacing corn starch (CS) energy with isolated soy protein (ISP) and soybean oil (SO) and the ambient temperature affect the protein and energy requirements for maintenance and gain of European quail. Thus, a total of 432 European quail from 10 to 30 days of age, distributed in a completely randomized design, were used to estimate the protein and energy requirements for maintenance through the comparative slaughter methodology. The treatments consisted of three diets formulated with the replacement of CS, corresponding to 15% of the metabolizable energy in the diet, with ISP and SO, two controlled temperatures (26 and 35 °C), and three levels of feed supply (ad libitum, and 70 and 40% of ad libitum intake), with four replicates of six birds. Protein and energy requirements for weight gain were determined from 160 European quail, slaughtered every five days at 10, 15, 20, 25, and 30 days of age. Birds were housed in four groups of 40 birds in a room with thermoneutral temperature (26 °C). The energy sources of the feed and temperatures studied affected protein and energy requirements for maintenance and gain of European quail. Replacing CS energy by 15% of dietary energy with SO results in lower protein and energy maintenance requirements for European quail at both temperatures. The protein and energy weight gain requirements of quail fed SO as an energy source is higher than CS and ISP.(AU)

One size doesn't fit all: Singularities in bat species richness and activity patterns in wind-energy complexes in Brazil and implications for environmental assessment

Wind energy is an important electricity source. Even though it is cleaner than other energy sources in terms of greenhouse gas emissions, gathering energy from the wind has impact on organisms that fly, including bats. Understanding whether and how bat activity patterns are affected by environmental variables may be useful when trying to mitigate these impacts, for example bat mortality from collisions with wind turbines. Northeastern Brazil concentrates one of the world's largest wind potentials and has thousands of wind turbines in operation. In spite of this scenario, there is a lack of basic information, such as the presence of bat species and their activity patterns in those wind farms. We used passive acoustic monitoring to assess species richness and species composition and obtain data on activity patterns of insectivorous bats in four wind farm complexes in northeastern Brazil. We also investigated the possible correlation between environmental variables (wind speed and direction, air temperature and humidity, and percentage of moon illumination) and bat activity. The acoustic monitoring carried out for 30 nights produced approximately 120,000 bat passes of 29 sonotypes and four families. Environmental variables may influence bat activity, but in a site-specific way, i.e., although the environmental conditions of wind-energy complexes were similar, there was not an activity pattern common to all. Considering such specificities, we strongly recommend long-term specific on-site monitoring in each wind complex, avoiding generalizations for the environmental licensing of wind energy in Brazil.(AU)

Effect of exogenous emulsifier and different fat sources on the performance, carcass characteristics, nutrient digestibility, and serum lipid profile of broiler chickens / Efeito de emulsificante exógeno e diferentes fontes de gordura no desempenho, características de carcaça e digestibilidade de nutriente e perfil lipídico sérico em frangos de corte

A study was conducted to evaluate the effect of an emulsifier on reduced-energy diets using two fat sources for broilers. The study was designed as a 2 x 3 factorial arrangement of treatments. The first factor was 2 fat sources (poultry fat or beef tallow). The second factor was a basal diet with the recommended energy levels, a diet with a 0.83 MJ/kg of energy reduction, and a diet with an energy reduction and inclusion of 1 g emulsifier/kg of diet. The emulsifier used in this study was composed of soy lecithin and polyethylene glycol ricinoleate. The emulsifier increased apparent metabolizable energy (AME) and apparent metabolizable energy corrected for nitrogen balance (AMEn) in beef tallow diets compared to energy-reduced diets (P<0.001). Broilers fed poultry fat had higher weights and weight gains at 35 and 42 d of age (p=0.001), and they had higher daily deposition of fat in the carcass (P = 0.025) when compared to diets with beef tallow. The inclusion of emulsifiers in broiler diets improves AME and AMEn but did not affect the energy reduction diets, which resulted in reduced performance, decreasing daily fat deposition, but without effects on serum lipid profile in broilers.(AU)

Um estudo foi conduzido para avaliar o efeito de um emulsificante em dietas com baixo teor de energia usando duas fontes de gordura para frangos de corte. O estudo foi delineado em arranjo fatorial 2 x 3 de tratamentos, o primeiro fator foi 2 fontes de gordura (gordura de frango ou sebo bovino) e o segundo fator uma dieta basal com os níveis de energia recomendados, uma dieta com 0,83 MJ / kg de redução de energia e uma dieta com redução de energia e inclusão de 1 g de emulsionante / kg de dieta (composto de lecitina de soja e ricinoleato de polietilenoglicol). O emulsificante aumentou a energia metabolizável aparente (EMA) e a energia metabolizável aparente corrigida para o balanço de nitrogênio (EMAn) em dietas com sebo bovino em comparação com dietas com redução de energia (P <0,001). Frangos de corte alimentados com gordura de frango apresentam maiores pesos e ganhos de peso aos 35 e 42 dias de idade (p=0,001), e maior deposição diária de gordura na carcaça (P=0,025) quando comparados às dietas com sebo bovino. O emulsificante incluído nas dietas de frangos de corte melhora a EMA e EMAn, mas não supre a redução energética, causando efeitos negativos no desempenho, diminuindo a deposição diária de gordura, mas sem efeitos no perfil lipídico sérico em frangos de corte.(AU)

The sperm mitochondria: clues and challenges

Sperm cells rely on different substrates to fulfil thei energy demand for different functions and diverse moments of their life. Species specific mechanism involve both energy substrate transport and their utilization: hexose transporters, a protein family of facilitative passive transporters of glucose and other hexose, have been identified in spermatozoa of different species and, within the species, their localization has been identified and, in some cases, linked to specific glycilitic enzyme presence. The catabolism of hexose sources for energy purposes has been studied in various species, and recent advances has been made in the knowledge of metabolic strategies of sperm cells. In particular, the importance of aerobic metabolism has been defined and described in horse, boar and even mouse spermatozoa; bull sperm cells demonstrate to have a good adaptability and capacity to switch between glycolysis and oxidative phosphorylation; finally, dog sperm cells have been demonstrated to have a great plasticity in energy metabolism management, being also able to activate the anabolic pathway of glycogen syntesis. In conclusion, the study of energy management and mitochondrial function in spermatozoa of different specie furnishes important base knowledge to define new media for preservation as well as newbases for reproductive biotechnologies.(AU)

Comparison of chemical composition, energy content, and digestibility of different sources of distillers corn oil and soybean oil for pigs

The objective of this study was to determine and compare the chemical composition; oxidation indicators; ether extract (EE) digestibility; and digestible, metabolizable, and net energy (DE, ME, and NE, respectively) content of distillers corn oil (DCO) from Brazil (CBR) and the United States (CUS), with refined (RSB) and degummed soybean oil (DSB) from Brazil offered to pigs. Fifty crossbred barrows (23.1±3.4 kg body weight) were fed a corn-soybean meal basal diet, or diets composed of 90% basal diet and 10% of one of the four oil sources (CBR, CUS, RSB, or DSB). Pigs were fed an amount of their respective experimental diets equivalent to 2.8 times the maintenance DE requirement for 9 d (sequentially 7 d for adaptation and 2 d for partial collection of feces). Distillers corn oil from Brazil contained lower linoleic acid (47.4%) than CUS (53.9%), RSB (54.2%), and DSB (51.5%), but greater contents of oleic (32.1%) and palmitic (14.6%) acids compared to CUS (27.0 and 12.9%), RSB (22.9 and 11.2%), and DSB (23.5 and 11.2%). The moisture and unsaponifiable contents of CBR (0.17 and 1.64%) and CUS (0.20 and 1.64%) were similar, but greater than the values found for RSB (0.05 and 1.20%) and DSB (0.12 and 1.02%). The anisidine value, free fatty acid content, and acidity of DCO samples were higher than soybean oils. The peroxide value and thiobarbituric reactive substances content increased in the oil samples over time. The apparent total tract digestibility (ATTD) of gross energy and the DE, ME and NE values of the oils did not differ among oil sources and ranged from 87.8 to 91.5%, and from 8280 to 8630, 8139 to 8459, and 7162 to 7444 kcal/kg, respectively. The ATTD of EE was greater in RSB and DSB than for CBR, but similar to CUS. The DCO produced in Brazil is an excellent energy source for pigs, with DE, ME, and NE values similar to those of DCO from the US and soybean oils.(AU)

Lipídios em dietas para ruminantes e seus efeitos sobre a qualidade da carne

Para satisfacer la demanda de los consumidores, cada vez más preocupados por la salud y el bienestar, se han adoptado estrategias como la modificación del perfil de ácidos grasos de productos de rumiantes (carne y leche) para obtener una menor proporción de ácidos grasos saturados (AGS) que son generalmente asociado con el riesgo de desarrollar enfermedad cardiovascular. La inclusión de fuentes lipídicas, como los aceites vegetales, ricos en ácidos grasos insaturados en la dieta de los rumiantes, ha tenido como objetivo mejorar la eficiencia del uso energético, ya que tiene un menor aumento calórico en comparación con los carbohidratos, así como mejorar la calidad cualitativa. aspectos de la carne, principalmente en lo que respecta al perfil de ácidos grasos, y al aumento de los compuestos funcionales de la carne. Sin embargo, debido a que la naturaleza alimentaria de los rumiantes está asociada al consumo de forrajes, los cuales son pobres en este nutriente, existe una limitación en su uso, ya que son tóxicos para los microorganismos ruminales. Así, se han realizado investigaciones que evalúan la inclusión de fuentes lipídicas en la dieta de los rumiantes como alternativa alimentaria para mejorar la calidad de la carne, minimizando los efectos sobre la fermentación ruminal.

To meet the demand of consumers, increasingly concerned about health and well-being, strategies such as modifying the fatty acid profile of products from ruminants (meat and milk) have been adopted to obtain a lower proportion of saturated fatty acids (SFA) which are generally associated with the risk of developing cardiovascular disease. The inclusion of lipid sources, such as vegetable oils, rich in unsaturated fatty acids in the diet of ruminants, has been aimed at improving the efficiency of energy use, as it has a lower caloric increase compared to carbohydrates, as well as improving the qualitative aspects of the meat, mainly with regard to the fatty acid profile, and the increase in the functional compounds of the meat. However, because the food nature of ruminants is associated with the consumption of forages, which are poor in this nutrient, there is a limitation in their use, since they are toxic to ruminal microorganisms. Thus, researches evaluating the inclusion of lipid sources in the diet of ruminant animals have been carried out as a food alternative to improve meat quality, minimizing the effects on ruminal fermentation.

Para atender a demanda dos consumidores, cada vez mais preocupados com a saúde e bem estar, estratégias como a modificação do perfil de ácidos graxos dos produtos oriundos de ruminantes (carne e leite) têm sido adotadas, para obter uma menor proporção de ácidos graxos saturados (AGS) os quais geralmente estão associados ao risco de desenvolvimento de doenças cardiovasculares. A inclusão de fontes lipídicas, como por exemplo os óleos vegetais, ricos em ácidos graxos insaturados na dieta de ruminantes, têm tido como objetivo melhorar a eficiência de utilização de energia, uma vez que apresenta menor incremento calórico em comparação aos carboidratos, bem como melhorar os aspectos qualitativos da carne, principalmente no que se refere ao perfil de ácidos graxos, e aumento dos compostos funcionais da carne. Entretanto, devido à natureza alimentar dos ruminantes ser associada ao consumo de forragens, pobres nesse nutriente, há uma limitação em sua utilização, uma vez que são tóxicos aos microrganismos ruminais. Assim, pesquisas avaliando a inclusão de fontes lipídicas na dieta de animais ruminantes, têm sido realizadas como alternativa alimentar para melhorar a qualidade da carne, minimizando os efeitos sobre a fermentação ruminal.

Sources of acid insoluble ash as marker of corn digestibility in broilers / Fontes de cinza insolúvel em ácido como indicador de digestibilidade do milho em frangos de corte

The objective was to evaluate three sources of acid insoluble ash (AIA) (celite, kaolin, and sand), as indicators, to determine the apparent metabolizable energy of corn on a natural matter (AME) basis, dry matter digestibility coefficient (DMDC), and crude protein digestibility coefficient (CPDC) using total and partial excreta collection methods. Two hundred and ten Ross broiler chicks of 18 to 27 days of age were used. Broilers were adapted to experimental the diet for four days, and excreta were collected for 5 days. A reference diet (RD) based on corn and soybean meal was prepared to meet the nutritional requirements of the birds. A test diet was prepared with 40% replacement of RD with corn. The formulated diets were: D1, 99% Reference diet + 1% celite; D2, 59.4% RD + 39.6 % corn + 1% celite; D3, 99% Reference diet + 1% kaolin; D4, 59.4% RD + 39.6 % corn + 1% kaolin; D5, 99% Reference diet + 1% sand; D6, 59.4% RD + 39.6 % corn + 1% sand. The treatments were distributed in a completely randomized design, with six diets and five replicates of seven birds each in a 2x3 factorial arrangement. There were significant interactions for all variables investigated. It was observed that the AME and DMDC values of corn were similar in the two methods of collection, and CPDC values using kaolin and celite makers were similar. However, the AME and CPDC of corn using sand with partial collection method were underestimated by 17.70 and 15.53%, respectively compared to those with the total collection method. The AME values of corn with the collection methods using celite and, the DMDC using celite and sand were significantly different. It was observed that the DMDC using celite and sand provided significantly lower values (4.67 and 5.15%), respectively, and the AME using celite was 2.86% lower than that obtained by total collection. To determine the EMA, DMDC, and CPDC in broilers, it is more efficient to use celiteTM and kaolin as markers with partial collection of excreta. Sand should not be used with partial excreta collection method, because it provides lower values of AME and CPDC compared to with total excreta collection method.(AU)

Objetivou-se avaliar três fontes de cinza insolúvel em ácido (CIA) (celite, caulim, e areia), como indicadores para determinação da energia metabolizável aparente do milho na matéria natural (EMA), coeficiente de digestibilidade da matéria seca (CDMS), e coeficiente de digestibilidade da proteína bruta (CDPB) por meio dos métodos de coleta total e parcial de excretas. Foram utilizados duzentos e dez frangos da linhagem comercial Ross no período de 18 a 27 dias de idade. Os frangos foram adaptados à dieta experimental por quatro dias, e as excretas foram coletadas por 5 dias. Foi formulada uma dieta referência (DR) a base de milho e farelo de soja para atender as exigências nutricionais das aves. A dieta teste com substituição de 40% de milho à DR. As dietas formuladas foram: D1, 99% dieta referência + 1% celite; D2, 59.4% DR + 39.6 % milho + 1% celite; D3, 99% dieta referência + 1% caulim; D4, 59.4% RD + 39.6 % milho + 1% caulim; D5, 99% dieta referência + 1% areia; D6, 59.4% DR + 39.6 % milho + 1% areia. Os tratamentos foram distribuídos em delineamento inteiramente casualizado, com seis dietas e cinco repetições de 7 aves cada em esquema fatorial 2x3. Houve interações significativas para todas as variáveis investigadas. Observouse que os valores de EMA e CDMS do milho são semelhantes pelos dois métodos de coleta utilizando caulim, e CDPB utilizando caulim e celite. Contudo, a EMA e o CDPB do milho usando areia na coleta parcial foram subestimados em 17,70 e 15,53%, respectivamente, em relação à coleta total. Os valores EMA do milho para os métodos de coleta usando celite e, o CDMS usando celite e areia foram significativamente diferentes. Observou-se que o CDMS com celite e areia proporcionou valores significativamente menores (4,67 e 5,15%), respectivamente, e a EMA com celite foi 2,86% menor que o obtido pela coleta total. Para determinar a EMA, CDMS e CDPB em frangos de corte, é mais eficiente usar celiteTM e caulim como indicadores na coleta parcial de excretas. A areia não deve ser usada com o método de coleta parcial de excretas, pois fornece valores menores de EMA e CDPB em comparação com o método de coleta total de excretas.(AU)

Lipídios em dietas para ruminantes e seus efeitos sobre a qualidade da carne / Lipids in ruminant diets and their effects on meat quality

Para atender a demanda dos consumidores, cada vez mais preocupados com a saúde e bem estar, estratégias como a modificação do perfil de ácidos graxos dos produtos oriundos de ruminantes (carne e leite) têm sido adotadas, para obter uma menor proporção de ácidos graxos saturados (AGS) os quais geralmente estão associados ao risco de desenvolvimento de doenças cardiovasculares. A inclusão de fontes lipídicas, como por exemplo os óleos vegetais, ricos em ácidos graxos insaturados na dieta de ruminantes, têm tido como objetivo melhorar a eficiência de utilização de energia, uma vez que apresenta menor incremento calórico em comparação aos carboidratos, bem como melhorar os aspectos qualitativos da carne, principalmente no que se refere ao perfil de ácidos graxos, e aumento dos compostos funcionais da carne. Entretanto, devido à natureza alimentar dos ruminantes ser associada ao consumo de forragens, pobres nesse nutriente, há uma limitação em sua utilização, uma vez que são tóxicos aos microrganismos ruminais. Assim, pesquisas avaliando a inclusão de fontes lipídicas na dieta de animais ruminantes, têm sido realizadas como alternativa alimentar para melhorar a qualidade da carne, minimizando os efeitos sobre a fermentação ruminal.(AU)

To meet the demand of consumers, increasingly concerned about health and well-being, strategies such as modifying the fatty acid profile of products from ruminants (meat and milk) have been adopted to obtain a lower proportion of saturated fatty acids (SFA) which are generally associated with the risk of developing cardiovascular disease. The inclusion of lipid sources, such as vegetable oils, rich in unsaturated fatty acids in the diet of ruminants, has been aimed at improving the efficiency of energy use, as it has a lower caloric increase compared to carbohydrates, as well as improving the qualitative aspects of the meat, mainly with regard to the fatty acid profile, and the increase in the functional compounds of the meat. However, because the food nature of ruminants is associated with the consumption of forages, which are poor in this nutrient, there is a limitation in their use, since they are toxic to ruminal microorganisms. Thus, researches evaluating the inclusion of lipid sources in the diet of ruminant animals have been carried out as a food alternative to improve meat quality, minimizing the effects on ruminal fermentation.(AU)

Para satisfacer la demanda de los consumidores, cada vez más preocupados por la salud y el bienestar, se han adoptado estrategias como la modificación del perfil de ácidos grasos de productos de rumiantes (carne y leche) para obtener una menor proporción de ácidos grasos saturados (AGS) que son generalmente asociado con el riesgo de desarrollar enfermedad cardiovascular. La inclusión de fuentes lipídicas, como los aceites vegetales, ricos en ácidos grasos insaturados en la dieta de los rumiantes, ha tenido como objetivo mejorar la eficiencia del uso energético, ya que tiene un menor aumento calórico en comparación con los carbohidratos, así como mejorar la calidad cualitativa. aspectos de la carne, principalmente en lo que respecta al perfil de ácidos grasos, y al aumento de los compuestos funcionales de la carne. Sin embargo, debido a que la naturaleza alimentaria de los rumiantes está asociada al consumo de forrajes, los cuales son pobres en este nutriente, existe una limitación en su uso, ya que son tóxicos para los microorganismos ruminales. Así, se han realizado investigaciones que evalúan la inclusión de fuentes lipídicas en la dieta de los rumiantes como alternativa alimentaria para mejorar la calidad de la carne, minimizando los efectos sobre la fermentación ruminal.(AU)

Beta-glucanases e xilanases na nutrição de não ruminantes / Beta-glucanases and xylanases in non-ruminant nutrition / Beta glucanasas y xilanasas en la nutrición de no rumiantes

A busca por custo x benefício na avicultura envolve compreender como melhorar o desempenho animal através da alimentação ao mesmo tempo em que haja diminuição dos custos. Tendo em vista o crescente aumento monetário da matéria prima da ração, várias pesquisas se voltam para novas fontes energéticas derivados de plantas, que contem quantidades significativas de fibras e agem como fatores antinutricionais, interferindo no desempenho zootécnico das aves. Os principais componentes das fibras, as beta glucanas e xilanas, podem ser quebradas e melhor aproveitadas quando no uso de enzimas exógenas chamadas de carboidrases, sendo a beta glucanase e xilase as respectivas enzimas que fazem a lise desses componentes. É necessário, portanto, melhor compreensão da forma de ação de cada enzima, assim como a fonte nutritiva das bases alimentares alternativas. Essa obra tem por objetivo abordar e revisar as duas principais fontes de fibras, beta glucanas e xilanas, e suas respectivas enzimas, beta glucanase e xilase.(AU)

The pursuit for cost-benefit in poultry farming involves understanding how to improve animal performance through feeding while reducing costs. In view of the growing monetary increase in feed raw material, several researches are focused on new energy sources derived from plants, which contain significant amounts of fiber and act as anti-nutritional factors, interfering with the zootechnical performance of birds. The main components of fiber, beta glucans and xylans, can be broken down and better utilized when using exogenous enzymes called carbohydrases, with beta glucanase and xylase being the respective enzymes that lyse these components. It is therefore necessary to better understand the mode of action of each enzyme, as well as the nutritive source of alternative food bases. This work aims to address and review the two main sources of fiber, beta glucans and xylans, and their respective enzymes, beta glucanase and xylase.(AU)

La búsqueda de la relación costo-beneficio en la avicultura implica comprender cómo mejorar el rendimiento animal a través de la alimentación y reducir los costos. Ante el creciente aumento monetario de la materia prima de los alimentos, varias investigaciones se enfocan en nuevas fuentes de energía derivadas de las plantas, que contienen cantidades significativas de fibra y actúan como factores antinutricionales, interfiriendo en el desempeño zootécnico de las aves. Los principales componentes de la fibra, los betaglucanos y los xilanos, se pueden descomponer y utilizar mejor cuando se usan enzimas exógenas llamadas carbohidrasas, siendo la betaglucanasa y la xilasa las enzimas respectivas que lisan estos componentes. Por lo tanto, es necesario comprender mejor el modo de acción de cada enzima, así como la fuente nutritiva de las bases alimenticias alternativas. Este trabajo tiene como objetivo abordar y revisar las dos principales fuentes de fibra, beta glucanos y xilanos, y sus respectivas enzimas, beta glucanasa y xilasa.(AU)

Substitution of dry corn grain by rehydrated and ensiled corn grain, finely or coarsely ground, on performance of young bulls finished in feedlot

We investigated the effects of corn grain, finely or coarsely ground, rehydrated and ensiled to 35% moisture in substitution of dry corn grain on performance of beef cattle in the feedlot. Forty non-castrated young Angus crossbred bulls with average age of 13±1.4 months and average initial body weight (BW) of 374±14 kg. The experiment was conducted in blocks by weight, and bulls were randomly assigned into four groups of five animals each in a 2 × 2 factorial scheme. The factors evaluated were particle size (finely and coarsely ground) and two grain sources (dry ground corn and rehydrated corn grain silage). The treatments were diets containing dry corn grain, finely ground (DCF; 1.86 mm); dry corn grain, coarsely ground (DCC; 3.53 mm); rehydrated and ensiled corn grain, finely ground (RCF; 1.86 mm); and rehydrated and ensiled corn grain, coarsely ground (RCC; 3.53 mm). Initial BW, final BW, average daily gain (ADG), feed efficiency, and intake of dry matter (DMI), acid detergent fiber, and metabolizable energy were not affected by treatment. Ensiling corn grain decreased DMI by 10.3% (11.6 vs. 10.4 kg/d for dry and ensiled, respectively) and increased feed efficiency by 13.3% (0.13 vs. 0.15 kg/d for dry and ensiled, respectively), but there was no effect of particle size, grain source, and their interaction on ADG. Effects of particle size and grain source were observed for fecal starch and total tract starch digestion, with evidence that treatments containing rehydrated corn diets showed greater efficiency in the utilization of dietary starch. Animals fed RCF diets showed lower fecal starch losses of 37, 55, and 75% when compared with treatments RCC, DCF, and DCC, respectively. Our results suggested that ensiled rehydrated corn grain improves feed efficiency in substitution of dry corn grain. The finely and coarsely ground of rehydrated and ensiled corn grain increases the digestibility of starch for finishing cattle in feedlot.(AU)

Canine visceral leishmaniasis in Rio Grande do Norte state, Northeastern Brazil - spatial analysis

Background: Human visceral leishmaniasis (HVL) is a potentially fatal disease with a worldwide distribution, being endemic in 12 countries in the Americas. The main reservoir in the urban environment is the dog, whose cases precede the disease in humans. For the control of HVL, the Ministry of Health of Brazil recommends efficiency in the notification of human cases, control of sandflies, elimination of reservoirs and health education, in addition to the interruption in the transmission of the disease by the intensification of surveillance and control of priority areas based on identification by spatial analysis. The objective of the study was to investigate the spatial distribution of canine visceral leishmaniasis (CVL) in the state of Rio Grande do Norte, Brazil, determining areas of risk by identifying spatial clusters, with a view to monitoring and implementing preventive actions. Materials, Methods & Results: Secondary data from sample and/or routine serological surveys for serological diagnosis of LVC in the period from 2011 to 2018 were used. The inclusion of animals in the routine diagnosis per municipality resulted from demands of veterinarians, veterinary clinics, dog tutors, zoonoses control centers and environmental surveillance. The spatial statistical analysis was performed with SatScan software version 9.6 for the detection of spatial clusters, based on using the statistical scan method. Of the total of 231,123 dogs tested in the period, 24,642 (10.6%) were seroreactive for CVL. During the study, the municipalities with the highest number of cases were Natal and Mossoró, with 9,671 and 4,514 cases, respectively. During the years 2011 to 2018, 38 significant clusters (P < 0.05) were identified that included one or more municipalities. Discussion: The state of Rio Grande do Norte has an urban environment susceptible to the occurrence of CVL, with climate and topography that favor the proliferation of the vector and housing in precarious socio-sanitary conditions. The high number of CVL cases in Natal can be explained by the fact that the city is considered endemic for CVL, characterized as an area of intense transmission of the disease, according to the Ministry of Health. In addition, public infrastructure in some locations is deficient and living conditions are unfavorable, so that there is a need to invest in effective protection measures for vector control, as well as a focus on health education, whose HVL control measures in the municipality need to be readjusted. The high rate of cases and the constant presence of clusters in the municipality of Açu can be explained by the increasing degradation of the Caatinga biome, evidenced by the removal of firewood for use in the ceramist pole, whose activity is concentrated on a large scale in the use of raw material and energy, through the production of charcoal, for agricultural and livestock fronts, putting species of fauna and flora at risk. It is also noteworthy that this fact contributes to the destruction of wild ecotopes, resulting in the search for the vector for other sources of human and animal food, allowing an increase in the number of cases of the disease. It's concluded that canine visceral leishmaniasis is distributed in a large part of the state of Rio Grande do Norte. The underreporting and/or deficiency in the disclosure of data by some municipalities represents a challenge in complying with the actions of the Visceral Leishmaniasis Surveillance and Control Program, and attention should be paid to the monitoring and inspection of the execution actions of municipal managers, as well as how to train professionals who are part of the service.

Economic viability of a canadian biodigester for power generation in dairy farming / Viabilidade econômica da implantação de um biodigestor tipo canadense para a geração de energia elétrica destinada à atividade leiteira

This study aimed to analyze the economic viability of implementing and using a Canadian biodigester for power generation in a milk production system. Specifically, we intended to estimate the generated power production, the total production cost (TC), the total operating cost (TOC), and the effective operating cost (EOC) of 1 kW of power generated, and estimate the break-even point of the power produced. The research was carried out on a farm located in southern Minas Gerais (Brazil) from January to December 2017. Three scenarios were analyzed through the tree-point estimation (most likely, optimistic, and pessimistic). Scenario 1 considered the use of power for the acclimatization of free-stall barns during 13 hours day-1 plus the use of 50% of the produced biofertilizer. Scenario 2 considered the use of power during 13 hours day-1 for the acclimatization of free-stall barns and milking parlor, which means an increase in power consumption estimated at 10% compared to scenario 1, plus the use of 75% of the produced biofertilizer. Moreover, scenario 3 considered the use of power for the acclimatization of free-stall barns during 6.5 hours day-1 plus 25% of the produced biofertilizer. All scenarios considered the amount charged per kWh by the Companhia Energética de Minas Gerais (CEMIG).(AU)

Objetivou-se analisar a viabilidade econômica da implantação e utilização de um biodigestor tipo canadense para a geração de energia elétrica em um sistema de produção de leite. Especificamente, pretendeu-se estimar a produção de energia elétrica gerada, estimar o custo total de produção (CT), custo operacional total (COT) e custo operacional efetivo (COE) de um kW de energia gerada, e estimar o ponto de equilíbrio de energia produzida. A pesquisa foi realizada em uma propriedade localizada no sul de Minas Gerais, no período entre janeiro a dezembro de 2017. Realizou-se a análise de cenários MOP (mais provável, otimista e pessimista): cenários 1; 2 e 3. No cenário 1, foram considerados a utilização de energia elétrica para a climatização apenas dos galpões de free stall em 13 h dia-1, mais aproveitamento de 50% do biofertilizante produzido. No cenário 2, a utilização da energia elétrica foi de 13 h dia-1, utilizada para climatização dos galpões de free stall e sala de ordenha, um aumento de energia estimado em 10%, em relação ao cenário 1, mais aproveitamento de 75% do biofertilizante produzido; e, no cenário 3, adotou-se a utilização de energia elétrica para a climatização dos galpões de free stall em 6,5 h dia-1, mais aproveitamento de 25% do biofertilizante produzido. Em todos os cenários foi considerado o valor cobrado por kWh pela Companhia Energética de Minas Gerais (CEMIG). Realizou-se simulações de Monte Carlo com taxas mínimas de atratividade variando de zero a 50%. A geração de energia elétrica apresentou viabilidade econômica em todos os cenários, apresentando valor presente líquido (VLP) positivos, taxas internas de retorno acima da taxa mínima de atratividade, payback simples e descontados abaixo do horizonte de 10 anos e relações benefício-custo satisfatórias. O COE de 1 kWh de energia elétrica foi estimado em R$ 0,1990, R$ 0,1791 e R$ 0,3308 para os cenários 1, 2 e 3, respectivamente, enquanto que o CT médio, considerando todos os cenários, foi de R$ 0,5618 (±0,21), acima dos valores de aquisição na CEMIG, que seria de R$ 0,50. Os CT foram de R$ 99.804,42 para os cenários 1 e 2, e de R$ 92.424,09 para o 3, com taxa mínima de atratividade de 8,50, enquanto que COT foi de R$ 69.486,62 nos cenários 1 e 2, e de R$ 62.229,66 no 3. Em todos os cenários, a quantidade de energia elétrica gerada foi superior ao ponto de equilíbrio. Todos os modelos de simulação de Monte Carlo apresentaram VPL positivos, indicando que há grande probabilidade de ficarem acima do esperado.(AU)

Economic viability of a canadian biodigester for power generation in dairy farming / Viabilidade econômica da implantação de um biodigestor tipo canadense para a geração de energia elétrica destinada à atividade leiteira

This study aimed to analyze the economic viability of implementing and using a Canadian biodigester for power generation in a milk production system. Specifically, we intended to estimate the generated power production, the total production cost (TC), the total operating cost (TOC), and the effective operating cost (EOC) of 1 kW of power generated, and estimate the break-even point of the power produced. The research was carried out on a farm located in southern Minas Gerais (Brazil) from January to December 2017. Three scenarios were analyzed through the tree-point estimation (most likely, optimistic, and pessimistic). Scenario 1 considered the use of power for the acclimatization of free-stall barns during 13 hours day-1 plus the use of 50% of the produced biofertilizer. Scenario 2 considered the use of power during 13 hours day-1 for the acclimatization of free-stall barns and milking parlor, which means an increase in power consumption estimated at 10% compared to scenario 1, plus the use of 75% of the produced biofertilizer. Moreover, scenario 3 considered the use of power for the acclimatization of free-stall barns during 6.5 hours day-1 plus 25% of the produced biofertilizer. All scenarios considered the amount charged per kWh by the Companhia Energética de Minas Gerais (CEMIG).

Objetivou-se analisar a viabilidade econômica da implantação e utilização de um biodigestor tipo canadense para a geração de energia elétrica em um sistema de produção de leite. Especificamente, pretendeu-se estimar a produção de energia elétrica gerada, estimar o custo total de produção (CT), custo operacional total (COT) e custo operacional efetivo (COE) de um kW de energia gerada, e estimar o ponto de equilíbrio de energia produzida. A pesquisa foi realizada em uma propriedade localizada no sul de Minas Gerais, no período entre janeiro a dezembro de 2017. Realizou-se a análise de cenários MOP (mais provável, otimista e pessimista): cenários 1; 2 e 3. No cenário 1, foram considerados a utilização de energia elétrica para a climatização apenas dos galpões de free stall em 13 h dia-1, mais aproveitamento de 50% do biofertilizante produzido. No cenário 2, a utilização da energia elétrica foi de 13 h dia-1, utilizada para climatização dos galpões de free stall e sala de ordenha, um aumento de energia estimado em 10%, em relação ao cenário 1, mais aproveitamento de 75% do biofertilizante produzido; e, no cenário 3, adotou-se a utilização de energia elétrica para a climatização dos galpões de free stall em 6,5 h dia-1, mais aproveitamento de 25% do biofertilizante produzido. Em todos os cenários foi considerado o valor cobrado por kWh pela Companhia Energética de Minas Gerais (CEMIG). Realizou-se simulações de Monte Carlo com taxas mínimas de atratividade variando de zero a 50%. A geração de energia elétrica apresentou viabilidade econômica em todos os cenários, apresentando valor presente líquido (VLP) positivos, taxas internas de retorno acima da taxa mínima de atratividade, payback simples e descontados abaixo do horizonte de 10 anos e relações benefício-custo satisfatórias. O COE de 1 kWh de energia elétrica foi estimado em R$ 0,1990, R$ 0,1791 e R$ 0,3308 para os cenários 1, 2 e 3, respectivamente, enquanto que o CT médio, considerando todos os cenários, foi de R$ 0,5618 (±0,21), acima dos valores de aquisição na CEMIG, que seria de R$ 0,50. Os CT foram de R$ 99.804,42 para os cenários 1 e 2, e de R$ 92.424,09 para o 3, com taxa mínima de atratividade de 8,50, enquanto que COT foi de R$ 69.486,62 nos cenários 1 e 2, e de R$ 62.229,66 no 3. Em todos os cenários, a quantidade de energia elétrica gerada foi superior ao ponto de equilíbrio. Todos os modelos de simulação de Monte Carlo apresentaram VPL positivos, indicando que há grande probabilidade de ficarem acima do esperado.

Ontogenetic change in the diet of Semaprochilodus insignis (Characiformes: Prochilodontidae) during migration between two limnologically distinct environments in the Amazon Basin

Semaprochilodus insignis is an Amazonian migratory fish species, moving in large shoals between white- and black-water rivers. It has long been classified as a detritivorous fish. However, it is possible that the trophic plasticity of S. insignis could be higher than previously assumed. The objective of this study was to investigate the relative contributions of autotrophic energy sources to the diet of S. insignis in the Negro and Solimões rivers and to determine if the species undergoes an ontogenetic change in the diet. We found variations between the δ13C and δ15N values of S. insignis between the rivers. In the Negro River, periphyton (84%) was the principal energy source for adults, while juveniles in the Solimões River foraged predominantly on terrestrial plants/C3 macrophytes (50%) and phytoplankton (42%). These variations in isotopic signatures are likely associated with migratory movements of S. insignis at different life stages and hydrological periods. Instead of the previously assumed dietary classification, we suggest that S. insignis varies its diet ontogenetically, with adults acting as illiophagous in black-water while the young are detritivorous in white-water rivers. The results show that this species creates complex links between food chains, thus emphasizing the importance of conserving flooded areas.(AU)

Semaprochilodus insignis é uma espécie de peixe migratório da Amazônia, movendo-se em cardumes entre rios de água branca e preta. Tem sido classificado como um peixe detritívoro-iliófago. Porém, é possível que a plasticidade trófica de S. insignis seja maior do que se supunha. O objetivo deste estudo foi investigar as contribuições relativas de fontes de energia autotróficas para a dieta do S. insignis nos rios Negro e Solimões e se a espécie muda ontogenticamente a sua dieta. Encontramos variações entre os valores de δ13C e δ15N de S. insignis entre os rios: Negro, o perifíton (84%) foi a principal fonte de energia para adultos, enquanto para os juvenis do rio Solimões, foram predominantemente as plantas terrestres/macrófitas C3 (50%) e fitoplâncton (42%). Essas variações nas assinaturas isotópicas provavelmente estão associadas a movimentos migratórios do S. insignis em diferentes estágios da vida e períodos hidrológicos. Ao invés da classificação alimentar previamente assumida, sugerimos que o S. insignis varie sua dieta ontogeneticamente, os adultos são iliófagos em águas negras, enquanto os jovens são detritívoros em rios de águas brancas. Os resultados demonstram que essa espécie promove ligações complexas entre as cadeias alimentares enfatizando, dessa forma, a importância da conservação das áreas inundadas amazônicas.(AU)

Ontogenetic change in the diet of Semaprochilodus insignis (Characiformes: Prochilodontidae) during migration between two limnologically distinct environments in the Amazon Basin

Semaprochilodus insignis is an Amazonian migratory fish species, moving in large shoals between white- and black-water rivers. It has long been classified as a detritivorous fish. However, it is possible that the trophic plasticity of S. insignis could be higher than previously assumed. The objective of this study was to investigate the relative contributions of autotrophic energy sources to the diet of S. insignis in the Negro and Solimões rivers and to determine if the species undergoes an ontogenetic change in the diet. We found variations between the δ13C and δ15N values of S. insignis between the rivers. In the Negro River, periphyton (84%) was the principal energy source for adults, while juveniles in the Solimões River foraged predominantly on terrestrial plants/C3 macrophytes (50%) and phytoplankton (42%). These variations in isotopic signatures are likely associated with migratory movements of S. insignis at different life stages and hydrological periods. Instead of the previously assumed dietary classification, we suggest that S. insignis varies its diet ontogenetically, with adults acting as illiophagous in black-water while the young are detritivorous in white-water rivers. The results show that this species creates complex links between food chains, thus emphasizing the importance of conserving flooded areas.(AU)

Semaprochilodus insignis é uma espécie de peixe migratório da Amazônia, movendo-se em cardumes entre rios de água branca e preta. Tem sido classificado como um peixe detritívoro-iliófago. Porém, é possível que a plasticidade trófica de S. insignis seja maior do que se supunha. O objetivo deste estudo foi investigar as contribuições relativas de fontes de energia autotróficas para a dieta do S. insignis nos rios Negro e Solimões e se a espécie muda ontogenticamente a sua dieta. Encontramos variações entre os valores de δ13C e δ15N de S. insignis entre os rios: Negro, o perifíton (84%) foi a principal fonte de energia para adultos, enquanto para os juvenis do rio Solimões, foram predominantemente as plantas terrestres/macrófitas C3 (50%) e fitoplâncton (42%). Essas variações nas assinaturas isotópicas provavelmente estão associadas a movimentos migratórios do S. insignis em diferentes estágios da vida e períodos hidrológicos. Ao invés da classificação alimentar previamente assumida, sugerimos que o S. insignis varie sua dieta ontogeneticamente, os adultos são iliófagos em águas negras, enquanto os jovens são detritívoros em rios de águas brancas. Os resultados demonstram que essa espécie promove ligações complexas entre as cadeias alimentares enfatizando, dessa forma, a importância da conservação das áreas inundadas amazônicas.(AU)

Influence of energy supplementation on associative effects in Nellore bulls on a tropical pasture during the rainy season / Influência da suplementação energética nos efeitos associativos em touros Nelore em pastagem tropical durante o período das águas

The objective of this study was to evaluate the influence of energy supplementation on associative effects between forage and concentrate supplements and on the performance of beef cattle on a tropical pasture during the rainy season. Twenty-eight Nellore bulls averaging 19 months of age and 325.2 ± 4.1 kg were allotted to a completely randomized design and distributed into four paddocks of two hectares each with a tropical pasture for 84 d. The treatments consisted of bulls on Urochloa brizantha cv. Xaraés pasture without concentrate supplementation or bulls on Urochloa brizantha cv. Xaraés pasture receiving concentrate supplementation at 15 (S15), 30 (S30) or 45% (S45) of the total digestible nutrients (TDN) requirement. All bulls had ad libitum access to mineral supplementation. The amount and chemical composition of the supplement were adjusted every 28 d. Forage and supplement intakes were evaluated in all animals using fecal markers. Crude protein: digestible organic matter ratio decreased with supplementation; consequently, the imbalance between dietary protein and energy increased. Forage intake decreased with increasing supplementation. The substitution rates of pasture for supplementary feed were 0.14, 0.33, and 0.46 for bulls from S15, S30, and S45 treatments, respectively. However, the apparent DM digestibility increased linearly with supplementation level. Supplementation improved the assimilation of ammonia-N in the rumen. Energy supplementation for Nellore bulls on tropical pastures during the rainy season provides excess energy relative to protein, resulting in a substitution effect of supplement intake on forage intake. Moreover, energy supplementation does not improve body weight gain. Protein sources should be added to supplements for balancing protein and energy levels, thereby reducing a likely substitution effect.(AU)

O objetivo deste trabalho foi avaliar a influência da suplementação energética nos efeitos associativos entre a forragem e suplemento concentrado e no desempenho de bovinos de corte em pasto tropical durante o período chuvoso. Vinte e oito touros da raça Nelore com idade média de 19 meses e 325,2 ± 4,1 kg foram alocados em delineamento inteiramente casualizado e distribuídos em quatro piquetes de dois hectares cada, com pasto tropical por 84 dias. Os tratamentos consistiram de touros em pastagem com Urochloa brizantha cv. Xaraés sem suplementação concentrada e touros em pastagem de Urochloa brizantha cv. Xaraés recebendo suplementação concentrada com 15 (S15), 30 (S30) ou 45% (S45) da necessidade de nutrientes digestíveis totais (NDT). Todos os touros tiveram acesso ad libitum à suplementação mineral. A quantidade e a composição química do suplemento foram ajustadas a cada 28 dias. A ingestão de forragem e suplemento foi avaliada em todos os animais por meio de marcadores fecais. A relação proteína bruta: matéria orgânica digestível diminuiu com a suplementação, consequentemente, o desequilíbrio entre proteína e energia da dieta aumentou. O consumo de forragem diminuiu, com efeito substitutivo do consumo de pasto pelo suplemento de 0,14, 0,33 e 0,46 para touros dos tratamentos S15, S30 e S45, respectivamente. No entanto, a digestibilidade aparente da MS aumentou linearmente com o nível de suplementação. A suplementação melhorou a assimilação do nitrogênio amoniacal no rúmen. A suplementação energética para touros Nelore em pastagens com pasto tropical durante a estação chuvosa fornece excesso de energia em relação à proteína, resultando em um efeito de substituição do consumo de forragem por suplemento. Além disso, a suplementação energética não melhora o ganho de peso corporal. Fontes de proteína devem ser adicionadas aos suplementos para equilibrar os níveis de proteína e energia, diminuindo um provável efeito de substituição.(AU)