Influência da palha e tempo de preparo da calda antes da hidrólise da cana-de-açúcar em dietas de vacas leiteiras
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2016-02-16
Autores
Endo, Viviane [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A cana-de-açúcar tem papel importante no agronegócio brasileiro para a produção de etanol e açúcar. A palha da cana-de-açúcar é um resíduo orgânico pobre em sacarose para produção de etanol e de baixo valor nutritivo para a alimentação animal. Devido a isso, o processo de queima dos canaviais ocorre em larga escala com intuito de facilitar a colheita da cana-de-açúcar, além de limpar o canavial para a próxima safra. Entretanto, a queima causa danos à saúde e impacto ambiental. No estudo foram avaliados dois fatores da cana-de-açúcar: a influência da palha e a influência dos tempos de preparo da calda de hidróxido de cálcio (Ca(OH)2) antes da hidrólise da cana-de-açúcar. Os parâmetros avaliados neste estudo foram: composição bromatológica, temperatura e pH da cana-de-açúcar, digestibilidade de nutrientes, desempenho de vacas leiteiras e uso de imagens de microscopia eletrônica de varredura (MEV) da cana-de-açúcar antes e após a digestão in vitro. O primeiro estudo foi um arranjo fatorial 2 x 5 [cana-de-açúcar com ou sem palha e cinco tempos de preparo da calda de Ca(OH)2 antes da hidrólise da cana-de-açúcar (72, 48, 24, 0,5 horas e sem preparo)]. No segundo estudo foi avaliado a digestibilidade in vitro dos nutrientes em um delineamento inteiramente casualizado, com cinco tratamentos: cana-de-açúcar fresca sem palha, HPT0,5 (cana-de-açúcar hidrolisada com palha e a calda preparada 0,5 horas antes da hidrólise), HPT72 (cana-de-açúcar hidrolisada com palha e a calda preparada 72 horas antes da hidrólise), HT0,5 e HT72, cana-de-açúcar hidrolisada sem palha usando os mesmos procedimentos de preparo da calda na cana-de-açúcar com palha. Posteriormente, utilizou-se um delineamento em quadrado latino 5 x 5 (cinco vacas em lactação e cinco tratamentos) para estudo de desempenho. Imagens de MEV foram feitas como complemento para visualização da cana-de-açúcar com e sem digestão in vitro. Como resultados, a cana-de-açúcar fresca sem palha e hidrolisada com palha e a calda preparada 72 horas antes apresentou menor teor de fibra em detergente neutro (FDN). O pH da cana-de-açúcar hidrolisada, devido à presença do agente alcalinizante foi maior em comparação à cana-de-açúcar fresca independente da palha. A temperatura foi influenciada pela palha, apresentando-se maior quando esta estava presente. Em relação à digestibilidade dos nutrientes, a cana-de-açúcar hidrolisada com palha, quando comparada à hidrolisada sem palha, apresentou menor digestibilidade in vitro de matéria seca (MS) e maior digestibilidade in vitro da FDN. Para o desempenho das vacas, houve menor consumo de MS para a cana-de-açúcar com palha em comparação à cana-deaçúcar sem palha. A produção de leite manteve-se constante entre os tratamentos, assim como a sua composição. Nas imagens da MEV, algumas pequenas partículas de cana-de-açúcar que foram observadas nas amostras não digerida, após a digestão in vitro parecem ter sofrido alguma digestão. O que permaneceu foram partículas maiores, ou seja, partículas indigestíveis. A utilização da cana-de-açúcar com palha e a calda de Ca(OH)2 preparada 72 horas antes da hidrólise é recomendada devido à melhor eficiência alimentar das vacas, além de facilitar a mão-de-obra.
Sugarcane has an important role in agribusiness because of ethanol and sugar production. Straw of sugarcane is an organic residue, it has low nutritional value to animal feed and a poor sucrose content which is used to produce ethanol. Because of this, burning of the sugarcane is performed on a large scale aiming to facilitate the sugarcane harvest, besides cleaning the sugarcane fields for the next crop. Burning, however, is not safe for health and causes harmful environmental impact. The study evaluated two sugarcane factors: the influence of straw and the time of lime preparation on the sugarcane hydrolysis. The variables analyzed on this study were: chemical composition, temperature and pH of sugarcane, nutrient digestibility, performance of dairy cows and the use of scanning electron microscopy (SEM) images of sugarcane before and after in vitro digestion. First study was arranged as a factorial 2 x 5 [sugarcane with or without straw and five times of the lime preparation before hydrolysis of sugarcane (72, 48, 24, 0.5 hours and no lime used)]. The lime used was calcium hydroxide (Ca(OH)2. In the second study the in vitro digestibility of nutrients was evaluated and arranged as a completely randomized design with five treatments: fresh sugarcane without straw, HST0.5 (hydrolyzed sugarcane with straw and the lime prepared 0.5 hours before the hydrolysis), HST72 (hydrolyzed sugarcane with straw and the lime prepared 72 hours before the hydrolysis), HT0.5 (hydrolyzed sugarcane without straw and the lime prepared 0.5 hours before the hydrolysis) and HT72 (hydrolyzed sugarcane without straw and the lime prepared 72 hours before the hydrolysis). Posteriorly, a Latin square design 5 x 5 five lactating cows and five treatments was arranged for performance of dairy cows. As complement, SEM images of sugarcane before and after the in vitro digestion were done. As results, fresh sugarcane without straw and hydrolyzed with straw and the lime prepared 72 hours in advance presented lower neutral detergent fiber (NDF) content. The pH of hydrolyzed sugarcane was higher compared to fresh sugarcane, due to the presence of the alkalizing agent, regardless of straw. Temperature was higher when the straw was present. Regarding the digestibility of nutrients, sugarcane with straw showed lower in vitro digestibility of dry matter (DM) and higher in vitro digestibility of NDF compared with hydrolyzed sugarcane. For the cow’s performance, a lower DM intake was observed for sugarcane with straw compared with sugarcane without straw. Milk production was similar among treatments, as well as its composition. Providing sugarcane with straw and the lime of Ca(OH)2 prepared 72 hours before hydrolysis of sugarcane is recommended because it provided better feed efficiency to the cows. Additionally, it facilitates the labor.
Sugarcane has an important role in agribusiness because of ethanol and sugar production. Straw of sugarcane is an organic residue, it has low nutritional value to animal feed and a poor sucrose content which is used to produce ethanol. Because of this, burning of the sugarcane is performed on a large scale aiming to facilitate the sugarcane harvest, besides cleaning the sugarcane fields for the next crop. Burning, however, is not safe for health and causes harmful environmental impact. The study evaluated two sugarcane factors: the influence of straw and the time of lime preparation on the sugarcane hydrolysis. The variables analyzed on this study were: chemical composition, temperature and pH of sugarcane, nutrient digestibility, performance of dairy cows and the use of scanning electron microscopy (SEM) images of sugarcane before and after in vitro digestion. First study was arranged as a factorial 2 x 5 [sugarcane with or without straw and five times of the lime preparation before hydrolysis of sugarcane (72, 48, 24, 0.5 hours and no lime used)]. The lime used was calcium hydroxide (Ca(OH)2. In the second study the in vitro digestibility of nutrients was evaluated and arranged as a completely randomized design with five treatments: fresh sugarcane without straw, HST0.5 (hydrolyzed sugarcane with straw and the lime prepared 0.5 hours before the hydrolysis), HST72 (hydrolyzed sugarcane with straw and the lime prepared 72 hours before the hydrolysis), HT0.5 (hydrolyzed sugarcane without straw and the lime prepared 0.5 hours before the hydrolysis) and HT72 (hydrolyzed sugarcane without straw and the lime prepared 72 hours before the hydrolysis). Posteriorly, a Latin square design 5 x 5 five lactating cows and five treatments was arranged for performance of dairy cows. As complement, SEM images of sugarcane before and after the in vitro digestion were done. As results, fresh sugarcane without straw and hydrolyzed with straw and the lime prepared 72 hours in advance presented lower neutral detergent fiber (NDF) content. The pH of hydrolyzed sugarcane was higher compared to fresh sugarcane, due to the presence of the alkalizing agent, regardless of straw. Temperature was higher when the straw was present. Regarding the digestibility of nutrients, sugarcane with straw showed lower in vitro digestibility of dry matter (DM) and higher in vitro digestibility of NDF compared with hydrolyzed sugarcane. For the cow’s performance, a lower DM intake was observed for sugarcane with straw compared with sugarcane without straw. Milk production was similar among treatments, as well as its composition. Providing sugarcane with straw and the lime of Ca(OH)2 prepared 72 hours before hydrolysis of sugarcane is recommended because it provided better feed efficiency to the cows. Additionally, it facilitates the labor.
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Palavras-chave
Eficiência alimentar, Hemicelulose, pH, Temperatura, Feed efficiency, Hemicellulose, Temperature