Portal de Pesquisa da BVS Veterinária

Tese em Português | VETTESES | ID: vtt-216127

Resumo

A conservacao de forragens e uma alternativa viavel para minimizar os efeitos da estacionalidade da producao de forragens em regioes semiaridas. Das diversas plantas forrageiras usadas para a ensilagem, a palma forrageira destaca-se por ter elevada producao de fitomassa e alto teor de carboidratos soluveis. Contudo, o teor proteico desta planta e baixo tornando-a inadequada para fornecimento exclusivo em dietas de ruminantes. Por esta razao, e razoavel considerar a adicao de uma fonte proteica no processo de ensilagem, principalmente se for uma leguminosa forrageira, o que melhoraria substancialmente o valor nutritivo das silagens mistas. Dentre as leguminosas forrageiras, a gliricidia ganha importancia por ser bem adaptada ao clima semiarido e por complementar o deficit nutricional da palma forrageira. Objetivou-se avaliar as populacoes microbianas, perfil fermentativo, as perdas fermentativas, a estabilidade aerobia e a composicao bromatologica de silagens de palma forrageira com diferentes niveis de adicao de gliricidia. O material foi coletado na EMBRAPA Semiarido, localizada em Petrolina-PE. As analises laboratoriais foram realizadas nas dependencias desta instituicao e no Laboratorio de Forragicultura da UFPB, Campus II, Areia-PB. O experimento foi conduzido de acordo com um delineamento inteiramente casualizado, com 3 repeticoes, em esquema fatorial (5 x 6). Os tratamentos consistiram em cinco niveis de adicao de gliricidia (0, 25, 50, 75 e 100%) e seis tempos de abertura (1, 7, 15, 30, 60 e 90). Para o ensaio de estabilidade aerobia utilizou-se um esquema fatorial 5 x 2, com 3 repeticoes, avaliando-se cinco niveis de adicao de gliricidia e dois tempos de exposicao ao ar (48 e 96 h). Os dados foram analisados por meio de analise de variancia e regressao. As medias no tempo foram comparadas pelo teste t a 5% de probabilidade. Houve interacao tratamento x abertura para o perfil fermentativo das silagens. Todas as silagens apresentaram valores de pH com indicativo de boa fermentacao (3,8 a 4,2), exceto para o nivel de inclusao de 100% (5,3). A producao de nitrogenio amoniacal, em media, nao passou de 3,4% (% N total). O teor de carboidratos soluveis diminuiu apos 90 dias do processo de ensilagem. A capacidade tampao aumentou conforme adicionou-se gliricidia, mas sem efeito negativo sobre a fermentacao das mesmas. Houve efeito de interacao tratamento x abertura para os acidos latico (AL), acetico (AC), propionico e relacao AL:AC, com teores considerados desejaveis. As silagens apresentaram minimas perdas por gases (PG) e efluentes (PE). As menores PG foram observadas nas silagens com 50% de adicao de gliricidia, enquanto os menores valores de PE foram observados nas silagens com inclusao de 75 e 100% de gliricidia. Verificou-se efeito da inclusao da gliricidia sobre a composicao bromatologica das silagens mistas nos teores de materia seca, materia mineral, materia organica e extrato etereo. Houve interacao tratamento x abertura para os teores de proteina bruta, fibra insoluvel em detergente neutro, fibra insoluvel em detergente acido, lignina, hemicelulose, proteina e cinza insoluvel em detergente neutro, aumentando conforme maior o nivel de inclusao da gliricidia. A gliricidia proporciona melhoria do valor nutritivo das silagens mistas com palma forrageira.

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The forage conservation is a feasible alternative to minimize the seasonality in forage production, mainly in semiarid regions. Among many forages used in ensiling process, the forage cactus has been highlighted due to its high biomass production and high level of water soluble carbohydrates. However, the protein content of this plant is very low, which makes unsuitable the exclusive use of cactus silage in ruminant diets. Because of that, the addition of a protein source in the ensiling process must be considered because it would lead to increases in the nutritive value of the mixed silages. From all legume forages, the gliricidia becomes important due to its adaptation to semiarid climate and also for complementing the nutritional deficit of the forage cactus. The objective of this work was to evaluate the microbial populations, fermentative profile, fermentative losses, aerobic stability and chemical composition of forage cactus silages with inclusion levels of gliricidia. The material was collected from EMBRAPA Semiarido located in Petrolina-PE. Laboratorial analysis was performed at this institution and at the Laboratorio de Forragicultura of UFPB, Campus II, Areia-PB. The experiment was conducted according to a completely randomized design with three replicates in a factorial scheme (5 x 6). The treatments consisted of five addition levels of gliricidia (0, 25, 50, 75 and 100%) and six opening periods (1, 7, 15, 30, 60 and 90 days). Aerobic stability assay was performed using a factorial scheme (5 x 2), with 3 replicates, evaluating five addition levels of gliricidia in two opening periods (48 and 96 h). Analysis of variance and regression equations were calculated with SISVAR 5.0 statistical program. All the means were compared by t test at the 5% probability level. There was an interaction of treatment x opening for fermentative profile of the silages. All silages showed normal pH values, indicating good fermentation (3.8 to 4.2), except in inclusion level of 100% (5.3). Ammoniacal nitrogen production was, on average, 3.4%. Water soluble carbohydrates content decreased after 90 days from ensiling process. Buffering capacity increased as gliricidia was added but was not observed difference on its fermentation. There was interaction of treatment x opening to lactic (LA), acetic (AA) and propionic acids (PA) as well as the LA:AA ratio, indicating satisfactory content. The silages had minimal gases (GL) and effluent (EL) losses. The lower GL were detected in silages with 50% of gliricidia inclusion, whereas the lower values of EL were detected in silages with 75 and 100% of gliricidia inclusion. It was observed effect of inclusion level on chemical composition of mixed silages in dry matter, organic matter, ash and ether extract contents. There was interaction of treatment x opening in crude protein, neutral detergent insoluble fiber, acid detergent insoluble fiber, lignin, hemicellulose, neutral detergent insoluble protein and ash contents. Thus, as the inclusion of gliricidia increased these contents were higher. The gliricidia provides improvements on nutritive value of mixed silages of forage cactus.

Biblioteca responsável: BR68.1