Avaliação do valor nutritivo e estabilidade aeróbia de silagem de palha de feijão-frade e maçã de baixo calibre
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2017-07-04
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Este trabalho teve como objetivo avaliar o valor nutritivo e estabilidade aeróbia de silagens de palha de feijão-frade (Vigna unguiculata (L.) Walp.) e maçã, com diferentes níveis de incorporação destas matérias-primas (15% de palha e 85% de maçã, P15, 30% de palha e 70% de maçã, P30) durante períodos de ensilagem de diferente duração (45 e 60 dias). A composição química das misturas foi determinada antes e após o processo de ensilagem. A avaliação da sua composição microbiológica foi realizada no momento de abertura dos silos laboratoriais (dia 0) e durante um período de 12 dias. A estabilidade aeróbia das silagens foi avaliada durante 12 dias, através da medição da evolução da diferença entre as temperaturas dos silos e a temperatura ambiente e do seu pH. De um modo geral, os resultados obtidos indicaram que o período de ensilagem não teve um efeito significativo (P>0,05) sobre as variáveis analisadas. Como seria expectável, as silagens com maior incorporação de palha apresentaram teores mais elevados em MS (314 vs. 199 g/kg), constituintes da parede celular (NDF, 567 vs. 525 g/kg MS, ADF, 411 vs. 373 g/kg MS, ADL, 109 vs. 100 g/kg MS) e PB (134 vs. 121 g/kg MS). Pelo contrário, as silagens com menor incorporação de palha apresentaram uma concentração superior em WSC (33 vs. 21 g/kg MS). No momento de abertura dos silos, a silagem P15 apresentou valores mais elevados de ácidos acético, propiónico e láctico, e um pH inferior (3,82 vs. 4,29). O ácido butírico não foi detetado em nenhuma das silagens. No momento de abertura do silo (dia 0), as silagens P30 foram as que apresentaram uma maior carga de BAL (0,33 vs. 7,14 log UFC/g), Enterobacteriaceae (3,31 log UFC/g vs. não detetadas) e leveduras e fungos (6,49 vs. 2,44 log UFC/g). Relativamente à estabilidade aeróbia, verificou-se que as silagens P30 apresentaram uma variação de temperatura mais elevada (+9 e +13,5ºC no período de ensilagem de 45 e 60 dias, respetivamente) quando comparada com a observada nas silagens P15 (+6ºC e +5ºC no período de ensilagem de 45 e 60 dias, respetivamente). Relativamente ao pH, a silagem P15 apresentou uma tendência clara para uma maior estabilidade dos seus valores durante o período de aerobiose. Os resultados obtidos neste estudo sugerem que o aumento da incorporação de maçã favoreceu o processo de ensilagem da palha de feijão-frade tendo-se obtido silagens estáveis no final dos dois períodos de ensilagem. Mais ainda, sugerem que o nível de incorporação de palha de 15% é o mais indicado para a obtenção de silagens estáveis após a abertura dos silos. Na medida em que a diminuição dos níveis de hidratos de carbono solúveis foi demasiado elevada em ambas as misturas, poder-se-á concluir que a utilização de aditivos que permitam uma acidificação mais rápida do material a ensilar poderá ser vantajosa
This work aimed to evaluate the nutritional value and aerobic stability of cowpea straw (Vigna unguiculata (L.) Walp.) and low caliber apple silage, at different levels of incorporation (15% apple with 30% straw, P15, and 30% apple with 70% straw, P30) and during different ensiling periods (45 and 60). The chemical composition of the mixtures was determined before and after the ensilage process. The evaluation of the microbiological composition was held at the opening of the laboratory silos (day 0) and during a period of 12 days. The aerobic stability of the silage was evaluated for 12 days by measuring the evolution of the difference between the temperatures of the silos and the room temperature and its pH. In general, the results indicated that the ensilage period had no significant effect (P>0,05) over the analyzed variables. On one hand, as expected, the silage with greater incorporation of straw had higher levels of dry matter (DM, 313.9 vs. 198.6 g / kg), cell wall constituents (NDF, 567 vs. 525 g/kg MS, ADF, 411 vs. 373 g/kg MS, ADL, 109 vs. 100 g/kg MS) and crude protein (134 vs. 121 g / kg DM). On the other hand, the silage with less straw incorporation showed the higher concentration of water-soluble carbohydrates (33 vs. 21 g / kg DM). Upon opening of the silo, P15 silage showed higher levels of acetic, propionic and lactic acid, and lower pH (3.82 versus 4.29). Butyric acid was not detected in any of the silages. In the silo opening time (day 0), the P30 silages showed a superior content of lactic acid bacteria (0.33 vs. 7.14 log CFU / g), Enterobacteriaceae (3.31 log UFC / g vs. undetected) and yeasts and fungi (6.49 vs. 2.44 log UFC / g). Regarding the aerobic stability, it was found that the P30 silage had a higher temperature range (9 and 13.5 ºC over 45 and 60 days of ensilage, respectively) compared to that observed in P15 silage (5 and 6 ºC over 45 and 60 days of ensilage, respectively). With regard to pH, P15 silage showed a clear tendency for a greater stability of its values during the aerobic period. The results of this study suggest that the addition of apple favored the ensiling process of cowpea straw as both silages were stable at the end of the two ensiling periods. Moreover, they suggests that the 15% straw incorporation level is the most suitable for obtaining stability after opening the silos. To the extent that the decrease of the soluble carbohydrate level was too high in both mixtures, it may be concluded that the use of additives enabling a more rapid acidification of the silage material can be advantageous.
This work aimed to evaluate the nutritional value and aerobic stability of cowpea straw (Vigna unguiculata (L.) Walp.) and low caliber apple silage, at different levels of incorporation (15% apple with 30% straw, P15, and 30% apple with 70% straw, P30) and during different ensiling periods (45 and 60). The chemical composition of the mixtures was determined before and after the ensilage process. The evaluation of the microbiological composition was held at the opening of the laboratory silos (day 0) and during a period of 12 days. The aerobic stability of the silage was evaluated for 12 days by measuring the evolution of the difference between the temperatures of the silos and the room temperature and its pH. In general, the results indicated that the ensilage period had no significant effect (P>0,05) over the analyzed variables. On one hand, as expected, the silage with greater incorporation of straw had higher levels of dry matter (DM, 313.9 vs. 198.6 g / kg), cell wall constituents (NDF, 567 vs. 525 g/kg MS, ADF, 411 vs. 373 g/kg MS, ADL, 109 vs. 100 g/kg MS) and crude protein (134 vs. 121 g / kg DM). On the other hand, the silage with less straw incorporation showed the higher concentration of water-soluble carbohydrates (33 vs. 21 g / kg DM). Upon opening of the silo, P15 silage showed higher levels of acetic, propionic and lactic acid, and lower pH (3.82 versus 4.29). Butyric acid was not detected in any of the silages. In the silo opening time (day 0), the P30 silages showed a superior content of lactic acid bacteria (0.33 vs. 7.14 log CFU / g), Enterobacteriaceae (3.31 log UFC / g vs. undetected) and yeasts and fungi (6.49 vs. 2.44 log UFC / g). Regarding the aerobic stability, it was found that the P30 silage had a higher temperature range (9 and 13.5 ºC over 45 and 60 days of ensilage, respectively) compared to that observed in P15 silage (5 and 6 ºC over 45 and 60 days of ensilage, respectively). With regard to pH, P15 silage showed a clear tendency for a greater stability of its values during the aerobic period. The results of this study suggest that the addition of apple favored the ensiling process of cowpea straw as both silages were stable at the end of the two ensiling periods. Moreover, they suggests that the 15% straw incorporation level is the most suitable for obtaining stability after opening the silos. To the extent that the decrease of the soluble carbohydrate level was too high in both mixtures, it may be concluded that the use of additives enabling a more rapid acidification of the silage material can be advantageous.
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Dissertação de Mestrado em Engenharia Zootécnica
Palavras-chave
Vigna unguiculata , Palha , Maçã , Silagem , Valor nutritivo , Deterioração , Estabilidade aeróbia , Alimentação dos animais