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Calorimetry, chemical composition and in vitro digestibility of sugarcane treated with calcium hydroxide
Sugar cane is a source of roughage in animal feeding. It presents high production per unit of cultivated area, relatively easy cultivation and low cost of production per hectare, better quality and a high DM yield in periods when forage is scarce. This study aimed to evaluate the effect of increasing levels of calcium hydroxide in sugarcane forage on chemical composition, and in vitro digestibility of DM, neutral detergent fiber (NDF), and acid detergent fiber (ADF), and kinetics of thermal decomposition processes of weight loss and heat flow. The sugarcane was collected close to the ground and were formed heaps of 50 kg, of fresh material, and mixed four doses of calcium hydroxide (Ca(OH)2) (0, 8, 16 and 24 g/kg of sugarcane in nature). Concentrations of NDF and ADF decreased linearly with higher amounts of calcium hydroxide, while that of hemicellulose increased linearly. The in vitro digestibility of DM, NDF, and ADF were enhanced quadratically with increasing amounts of calcium hydroxide added to sugarcane. The release of heat, measured by ∆H, augmented linearly with increased calcium hydroxide levels, which was likely representative of enhanced digestibility of the fiber components. Weight loss decreased linearly between 272.2 and 397.7°C with increased amounts of calcium oxide added to sugarcane, which was likely due to change in the structure of cellulose that became denser and thermodynamically more stable than native cellulose following the alkaline treatment. Calcium hydroxide changed chemical composition and digestibility of the fibrous fraction of sugarcane, resulting in better nutritional value. As the highest release of heat and in vitro digestibility of fiber were observed when adding 16 g calcium hydroxide per kilogram of sugarcane, this is the dose recommended to enhance the nutritive value of sugarcane as ruminant feed.
CP17287 Accepted 10 January 2018
© CSIRO 2018