Perfil fermentativo em silagem de ração total contendo capim-mombaça
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Data
2019-12-19
Autores
Brito, Vinícius Martins
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A silagem de ração total (SRT) é basicamente o produto da ensilagem conjunta do volumoso e do concentrado que pode substituir as misturas diárias para o preparo da ração total (RT). Além das vantagens operacionais, a SRT tem sido investigada no aproveitamento de coprodutos regionais com elevadas concentrações nutricionais, mas que tem seu armazenamento dificultado devido aos altos teores de umidade. Desta forma, a SRT seria viável no Brasil onde a produção dos capins tropicais apresenta um excedente em determinados períodos, mas os elevados teores de umidade não proporcionam uma capacidade de fermentação (CF) adequada. Com isso, o objetivo desse trabalho foi comparar o perfil fermentativo, químico-bromatológico e a digestibilidade in vitro entre as silagens RT e SRT contendo Megathyrsus maximus cv. Mombaça colhido em diferentes alturas. O delineamento experimental foi inteiramente casualizado com esquema em fatorial e cinco repetições, onde os fatores testados corresponderam a (i) duas estratégias de mistura do volumoso com o concentrado (rações RT e SRT); e (ii) duas alturas de colheita do capim Mombaça (alturas 70 e 130 cm). Os tratamentos correspondem a SRT com 50% de capim-Mombaça colhido a 70 cm de altura e 50% de concentrado (SRT70); SRT com 50% de capim-Mombaça colhido a 130 cm de altura e 50% de concentrado (SRT130); RT composta por capim-Mombaça colhido a 70 cm de altura e ensilado com polpa cítrica (RT70) e RT composta por capim-Mombaça colhido a 130 cm de altura ensilado com polpa cítrica (RT130). Os silos experimentais foram do tipo-fardo com aproximadamente 45 kg e compactados com o auxílio de uma prensa hidráulica com densidade média de 493±33 kg massa natural m-3. Para a coleta do efluente e estimativa da recuperação de matéria seca (RMS) foram acoplados no fundo de cada silo-fardo um saco de tecido de algodão previamente pesado e identificado com 14,6 kg de areia seca e peneirada. Após 95 dias do fechamento os silos foram pesados e abertos para a retirada de uma amostra por unidade experimental para a realização das análises laboratoriais. Os dados foram submetidos à análise de variância e as médias foram comparadas por meio de teste de T (P≤0,05). Os perfis fermentativo, nutricional e a digestibilidade foram afetados pelos diferentes tratamentos. As silagens exclusivas de capim-Mombaça e polpa cítrica apresentaram os menores valores de N-NH3 na comparação com as SRT (1,4; 1,8 e 2,3; 2,9 % do N total, respectivamente). Os maiores teores de ácido lático foram observados nas SRT (3,5 e 2,5 % MS). As maiores médias de MS foram observados em SRT e nos tratamentos com o capim ensilado a 130 cm de altura (27,6 e 28,0, respectivamente). Os valores de RMS não diferiram entre os tratamentos. No tratamento SRT130 foi observada a maior CF e menores perdas de MS na forma de efluente. Em SRT70 foi observado o menor valor de pH (4,2). A SRT diminuiu a concentração dos compostos fibrosos (FDN e FDA) e aumentou a taxa de DIVMO dessas silagens. A SRT pode ser realizada sem prejuízos a qualidade e perdas de massa seca da silagem.
Total ration silage (TRS) is basically the product of combined bulk and concentrate silage that can replace daily mixtures for total feed preparation (TF). In addition to the operational advantages, TRS has been increasingly investigated for the use of regional byproducts with high nutritional concentrations, but its storage for long periods is difficult due to the high humidity content. Thus, TRS would be viable in Brazil where the production of tropical grasses has a surplus in certain periods, but the high humidity contents do not provide an adequate fermentation capacity, causing dry matter (DM) losses and marked changes in chemical composition. Thus, the aim of this work was to compare the fermentative, chemical-bromatological profile and in vitro digestibility between TF and TRS silages containing Megathyrsus maximus cv. Mombaça harvested at different heights. The experimental design was completely randomized with factorial scheme and five replications, where the tested factors corresponded to (i) two strategies of mixture of roughage with concentrate (feed TF and TRS); and (ii) two harvest heights of Mombaça grass (heights 70 and 130 cm). The treatments correspond to TRS with 50% Mombaça grass harvested at 70 cm height and 50% concentrate (TRS70); TRS with 50% Mombaça grass harvested at 130 cm height and 50% concentrate (TRS130); TF composed of Mombaça grass harvested at 70 cm height and ensiled with citrus pulp (TF70) and TF composed of Mombaça grass harvested at 130 cm height ensiled with citrus pulp (TF130). The experimental silos were bale-type with approximately 45 kg and compacted with the aid of a hydraulic press with average density of 493 ± 33 kg. To collect the effluent and estimate the dry matter recovery (DMR) were coupled to the bottom of each silo-bale a bag of cotton cloth previously weighed and identified with 14.6 kg of dry and sieved sand. After 95 days of closure, the silos were weighed and opened for the removal of one subsample per experimental unit for laboratory analysis. Data were subjected to analysis of variance and means were compared by T-test (P≤0.05). Fermentation, nutritional profiles and digestibility were affected by different treatments. The exclusive silages of Mombaça grass and citrus pulp had the lowest N-NH3 values compared to TRS (1.4, 1.8 and 2.3; 2.9% of total N, respectively). The highest lactic acid contents were observed in the SRT (3.5 and 2.5% DM). The highest DM averages were observed in TRS and in the treatments with the ensiled grass at 130 cm height (27.6 and 28.0, respectively). The DMR values showed no interaction effect between the factors nor were affected by the grass ensiling height and the different diets formulations, being the average values of 93.1 and 92.8 and 91.7 and 94.2% for height and rations, respectively. In the SRT130 treatment, the highest FC and lower losses of DM in the effluent form were observed. In TRS70 the lowest pH value was observed (4.2). The TRS decreased the concentration of fibrous compounds (NDF and ADF) and increased the DIVMO rate of these silages. TRS can be performed without impairing the instructional quality and loss of dry mass of the silage.
Total ration silage (TRS) is basically the product of combined bulk and concentrate silage that can replace daily mixtures for total feed preparation (TF). In addition to the operational advantages, TRS has been increasingly investigated for the use of regional byproducts with high nutritional concentrations, but its storage for long periods is difficult due to the high humidity content. Thus, TRS would be viable in Brazil where the production of tropical grasses has a surplus in certain periods, but the high humidity contents do not provide an adequate fermentation capacity, causing dry matter (DM) losses and marked changes in chemical composition. Thus, the aim of this work was to compare the fermentative, chemical-bromatological profile and in vitro digestibility between TF and TRS silages containing Megathyrsus maximus cv. Mombaça harvested at different heights. The experimental design was completely randomized with factorial scheme and five replications, where the tested factors corresponded to (i) two strategies of mixture of roughage with concentrate (feed TF and TRS); and (ii) two harvest heights of Mombaça grass (heights 70 and 130 cm). The treatments correspond to TRS with 50% Mombaça grass harvested at 70 cm height and 50% concentrate (TRS70); TRS with 50% Mombaça grass harvested at 130 cm height and 50% concentrate (TRS130); TF composed of Mombaça grass harvested at 70 cm height and ensiled with citrus pulp (TF70) and TF composed of Mombaça grass harvested at 130 cm height ensiled with citrus pulp (TF130). The experimental silos were bale-type with approximately 45 kg and compacted with the aid of a hydraulic press with average density of 493 ± 33 kg. To collect the effluent and estimate the dry matter recovery (DMR) were coupled to the bottom of each silo-bale a bag of cotton cloth previously weighed and identified with 14.6 kg of dry and sieved sand. After 95 days of closure, the silos were weighed and opened for the removal of one subsample per experimental unit for laboratory analysis. Data were subjected to analysis of variance and means were compared by T-test (P≤0.05). Fermentation, nutritional profiles and digestibility were affected by different treatments. The exclusive silages of Mombaça grass and citrus pulp had the lowest N-NH3 values compared to TRS (1.4, 1.8 and 2.3; 2.9% of total N, respectively). The highest lactic acid contents were observed in the SRT (3.5 and 2.5% DM). The highest DM averages were observed in TRS and in the treatments with the ensiled grass at 130 cm height (27.6 and 28.0, respectively). The DMR values showed no interaction effect between the factors nor were affected by the grass ensiling height and the different diets formulations, being the average values of 93.1 and 92.8 and 91.7 and 94.2% for height and rations, respectively. In the SRT130 treatment, the highest FC and lower losses of DM in the effluent form were observed. In TRS70 the lowest pH value was observed (4.2). The TRS decreased the concentration of fibrous compounds (NDF and ADF) and increased the DIVMO rate of these silages. TRS can be performed without impairing the instructional quality and loss of dry mass of the silage.
Descrição
Palavras-chave
Volumoso, Capacidade de fermentação, Efluente, Effluent, Bulky, Fermentation capacity