The sward height at the early stockpiling period modifies the structural characteristics of marandu palisadegrass under continuous stocking

The control of sward height at the early stockpiling period influences the structural characteristics of stockpiled sward in winter. So, we conducted this work on the Cerrado region of Brazil based on the hypothesis that the reduction of pasture height at the beginning of stockpiling period results in: (i) lower stock of forage mass; and (ii) higher live leaf mass, but lower stem mass in stockpiled pasture during the winter. The treatments were four sward heights (15, 25, 35, and 45 cm) at early stockpiling period of marandu palisadegrass (Brachiaria brizantha syn. Urochloa brizantha cv. Marandu). The experiment was conducted in a completely randomized design, with three replications (paddocks with 800 m²). The stockpiled swards were evaluated during the grazing period in winter on days 7 (beginning), 45 (middle) and 90 (end). The vegetative tiller number (VEGT), live leaf mass (LLM) and leaf area index (LAI) were greater in the 15 cm stockpiled pasture than the other treatments. Greater heights (35 and 45 cm) at stockpiling resulted in greater forage mass than lower heights (15 and 25 cm). The VEGT, LLM, number of reproductive tillers, live stem mass, forage mass and LAI values were higher at the beginning than at the end of the grazing period. Our hypothesis has been proven, so that the reduction of sward height of the marandu palisadegrass at the beginning of the stockpiling period results in lesser forage mass, but with better structural characteristics.

Comparisons between intake values observed and predicted by nutritional systems for confined nellore cattle

This study compared the dry matter intake (DMI) of Nellore heifers and bulls in the feedlot, predicted by the BR-Corte (2010 and 2016) and NRC (2000) nutritional systems. Hence, two experiments were conducted in a completely randomized design. The first one used 47 Nellore bulls, not castrated, with an average initial weight of 413 kg, and 19 months of age. The second experiment used 24 Nellore heifers with an average initial weight of 300 kg and 23 months of age. The accuracy and approximation of the DMI estimates by the nutritional systems were adjusted with the simple linear regression model and the root mean square error of prediction (RMSEP). The DMI was 8.06 kg day-1 for Nellore heifers and 11.54 kg day-1 for bulls, which are higher than the values ​​ predicted by the nutritional systems. The NRC (2000) and BR-Corte (2010 and 2016) underestimated DMI in 20.84, 20.09, and 19.35% for heifers and 28.07, 16.20, and 11.78% for bulls, respectively. It was concluded that the BR-Corte 2010 and 2016 were the most suitable models to estimate the DMI of Nellore heifers and bulls for higher precision and accuracy.

Consumption of dry matter observed and predicted by the nutritional systems in senepol bulls kept in confinement / Consumo de matéria seca observado e previsto pelos sistemas nutricionais em touros senepol mantidos em confinamento

The objective was to compare the dry matter consumption (CMS) observed, through the use of the GrowSafe® electronic system, with that predicted by the BR-Corte (2010 and 2016) and NRC (2000) nutritional systems in confined Senepol bulls. To this end, 24 Senepol Bulls were used in a completely randomized design, uncastrated with an average initial weight of 368 kg and 16 months of age. The evaluation of the accuracy and approximation of the CMS estimates by the nutritional systems was adjusted by the simple linear regression model and the decomposition of the mean square of the prediction error (QMEP). The mean CMS observed was 10.33 kg.day-1, higher than the values predicted by the nutritional systems, in which the values predicted by the NRC (2000) and BR-Corte 2010 and 2016 underestimated the CMS by 29.62, 6.19 and 2.03%, respectively. The verification of QMEP and its decomposition made it possible to infer the proximity of the values predicted by the BR-Corte 2010 and 2016 models and the values observed, which presented a better adjustment in relation to the NRC. Surprisingly the values predicted by the NRC, created from a database with Bos taurus animals, showed greater distance from the values predicted and observed, and it was expected greater accuracy of the NRC models for this category and animal breed. It is concluded that the BR-Corte 2016 was the most appropriate model to estimate the CMS of confined Senepol bulls.

Objetivou-se comparar o consumo de matéria seca (CMS) observado, por meio do uso do sistema eletrônico GrowSafe®, com o predito pelos sistemas nutricionais BR-Corte (2010 e 2016) e NRC (2000) em touros da raça Senepol em confinamento. Para isso, foram utilizados 24 Touros da raça Senepol em delineamento inteiramente casualizado, não castrados com peso inicial médio 368 kg e 16 meses de idade. A avaliação da exatidão e aproximação das estimativas do CMS pelos sistemas nutricionais foi ajustada pelo modelo de regressão linear simples e decomposição do quadrado médio do erro de predição (QMEP). O CMS médio observado foi de 10,33 kg.dia-1, valor superior aos valores preditos pelos sistemas nutricionais, no qual os valores preditos pelo NRC (2000) e BR-Corte 2010 e 2016 subestimaram o CMS em 29,62, 6,19 e 2,03%, respectivamente. A verificação do QMEP e sua decomposição possibilitou inferir sobre a proximidade dos valores preditos pelos modelos BR-Corte 2010 e 2016 e os valores observados, os quais apresentaram melhor ajuste em relação ao NRC. Surpreendentemente os valores preditos pelo NRC, criado a partir de banco de dados com animais Bos taurus, apresentou maior distanciamento dos valores preditos e observados, sendo que era esperada maior precisão dos modelos NRC para esta categoria e raça animal. Conclui-se que o BR-Corte 2016 foi o modelo mais adequado para estimar o CMS de touros da raça Senepol em confinamento.

Intake and performance simulation of goats fed exclusively tifton 85, mulberry or leucaena / Simulação do consumo e do desempenho de caprinos alimentados exclusivamente com tifton 85, amoreira e leucena

Intake and performance of goats fed exclusively forages Tifton 85, mulberry or leucaena were simulated to verify which nutrients limit performance. Simulations were performed using the nutritional model similar to Cornell Net Carbohydrate and Protein System (CNCPS) with modifications related to the kinetic attributes of digestion and feed passage. The animal category chosen to perform the simulations was female Saanen goats in growing phase between weaning and mating, with 20 kg of body weight and 150 g of daily gain. The intake of 0.870 kg/day of Tifton 85 was adopted for performance simulations because in this point caused rumen fill and also attended the energy requirement of the animal. For performance simulations of mulberry, the amount of dry matter intake of 0.580 kg/day was adopted based on average intake obtained from the study of Sabino Jr. (1996) and simulations for leucaena used the intake of 0.220 kg/day, corresponding to 30g/100g of dry matter intake that would supply the energy requirement of these female goats. The limiting factor of performance of Saanen female growing goats fed exclusively Tifton 85 or mulberry is the metabolizable protein and not the energy. The intake of leucaena exclusively would be able to supply the requirement of metabolizable protein to promote the target weight gain of 150 g/day. The forages do not present perfect synchronization between carbohydrates and proteins, demonstrated by the positive ammoniacal balance in rumen environment that indicates an excess of nitrogen compounds supplied by these feed.

Simulações de consumo e desempenho de caprinos alimentados exclusivamente com as forrageiras Tifton 85, amoreira e leucena foram realizadas para verificar quais nutrientes seriam limitantes para o desempenho. Assimulações foram feitas utilizando o modelo similar ao Cornell Net Carbohydrate and Protein System (CNCPS) com algumas modificações em relação à cinética de digestão e passagem do alimento. A categoria animal escolhida foi a de cabritas Sannen em fase de crescimento entre o desmame e a puberdade, com 20 kg de peso corporal e ganho médio diário de 150 gramas por dia. Foi adotado o consumo de 0,870 kg/dia de Tifton 85 para realizar as simulações de desempenho, porque nesse ponto ocorreria repleção ruminal e ao mesmo tempo atenderia a demanda de energia do animal. Para simulações de desempenho da amoreira, foi adotada o consumo de matéria seca de 0,580 kg/dia obtido em estudo de Sabino Jr. (1996) e para as simulações com a leucena foi usado o consumo de matéria seca de 0,220 kg/dia, que corresponde à quantidade que iria suprir o requerimento de energia desses animais. O principal fator limitante do desempenho de fêmeas Saanen em crescimento alimentadas exclusivamente com Tifton 85 ou amoreira é a proteína metabolizável e não a energia. O consumo exclusivo de leucena seria capaz de suprir o requerimento de proteína metabolizável para promover ganho médio diário de 150 g/dia. As forrageiras não apresentaram perfeita sincronização entre carboidratos e proteína, verificado pelo balanço amoniacal positivo no rúmen, que indica excesso de nitrogênio desses alimentos.

In vitro degradation kinetics of protein and carbohydrate fractions of selected tropical forages / Cinética de degradação in vitro das frações de proteína e carboidrato em forrageiras tropicais

Whereas obtain detailed information about nutrient composition and degradation rates of carbohydrate and protein fractions of tropical forages is essential to determine how much of each nutrient can be used by the animal and the main limiting causes to the level of production. A descriptive study was conducted to evaluate the degradation rate of protein and carbohydrate fractions and understand degradation synchronism of carbohydrates and protein fraction in the rumen of goats fed Tifton 85, mulberry and leucaena forages. Contents of crude protein (CP), nonprotein nitrogen (NPN), neutral detergent insoluble nitrogen (NDIN) and acid detergent insoluble nitrogen (ADIN) were measured to obtain the protein fractions A, B1, B2 and C. Degradation profiles of nitrogen fractions were obtained in vitro incubating the forages samples with proteases from Streptomyces griseus. Contents of sugars, starch and soluble fiber (neutral detergent NDSF) were analyzed to determine the fractions A and B1 from total carbohydrates (TC), whereas for fraction B2, C and degradation rate of fraction B2, the gravimetric technique of in vitro degradation of the fiber was used through kinetic interpretation of degradation profiles. It was adopted descriptive statistics to summarize the dataset, to describe the data, tables were compiled and used sample average as position measurement. Regarding Tifton 85, the sum of fractions A and B1 was 51.61 g/100g CP and the fraction B2 was 38.74 g/100g CP. Thus, the portion of slowly degradable protein from this forage is higher and tends to escape from rumen contributing with amino acids in the small intestine. Differently, most of the protein from mulberry and leucaena are present as highly degradable protein in rumen (B1), requiring supplementation with readily fermentable carbohydrate for a better utilization of nitrogen compounds. Considering the partitions of protein in different compartments of the plant, possibly the mixture between forages promotes a better balance for the use of this nutrient by animals. Fractions representing about 80g/100g of the protein from Tifton 85 presents problems to be used by animals. This means that, despite the high levels of protein in Tifton 85, metabolizable protein deficit may occur at any time after the intake of forages by the animals. Mulberry and leucaena are extremely degradable feed, both for cellular content and cell wall, with high possibility of presenting good synchronization between degradation of carbohydrate and protein.

A obtenção de informações detalhadas sobre a composição dos nutrientes e a taxa de degradação das frações de carboidratos e proteínas é essencial para determinar quanto de cada nutriente pode ser usado pelo animal e quais as principais limitações para o nível de produção. Um estudo descritivo foi conduzido para avaliar a taxa de degradação das frações de carboidratos e proteína e compreender o sincronismo de degradação dessas frações no rúmen de cabras alimentadas com as forrageiras Tifton-85, amoreira e leucena. Os conteúdos de proteína bruta (PB), nitrogênio não protéico (NNP), nitrogênio insolúvel em detergente neutro (NIDN) e nitrogênio insolúvel em detergente ácido (NIDA) foram mensurados para obter as frações de protéicas A, B1, B2 e C. O perfil de degradação das frações de nitrogênio foram obtidas por incubação das forragens com proteases de Streptomyces griseus. Os conteúdos de açúcares, amido e fibra solúvel em detergente neutro (FSDN) foram analisados para determinar as frações A e B1 dos carboidratos totais (CT), sendo que para obtenção da fração B2, C e para taxa de degradação da fração B2, a técnica gravimétrica de degradação da fibra in vitro foi utilizada através da interpretação do perfil cinético de degradação. Foi utilizada a estatística descritiva para analisar os dados e como medida de posição foi adotada a média. Em relação ao Tifton 85, a soma das frações A e B1 foram 51.61 g/100g PB e a fração B2 foi 51.61 g/100g PB. Portanto, as frações de proteína de baixa degradação dessa forrageira são altas e tendem a escapar do rúmen e contribuir com aminoácidos no intestino delgado. Por outro lado, a maior parte da proteína da amoreira e leucena são altamente degradáveis no rúmen (B1), o que requer suplementação com carboidratos rapidamente fermentáveis para melhor utilização dos compostos nitrogenados. Considerando as partições da proteína nas diferentes partes da planta, é possível que a mistura entre essas forrageiras permita um melhor balanceamento para uso desse nutriente pelos animais. Cerca de 80g/100g de proteína do Tifton 85 apresentaram problemas de uso pelos animais. Isso significa que, apesar do alto nível de proteína nessa forrageira, deficiência de proteína metabolizável pode ocorrer em algum momento. Amoreira a leucena são alimentos com alta degradação, tanto do conteúdo celular como da parede celular, com alta possibilidade de apresentar boa sincronização entre a degradação de carboidratos e proteína.