AMMONIA TREATMENT FOR SUGAR-CANE HARVEST RESIDUES .1. DIGESTIBILITY AND CRUDE PROTEIN-CONTENT

Three experiments to evaluate the effect of ammonia treatment to sugar cane harvest residues on digestibility and crude protein content were carried out. Four grade Holstein heifers of 250 kg average LW were used to evaluate through an analysis of regression the effect of the duration of the ammonia treatment (0, 4, 7, 10 and 14 days) on dry matter digestibility. Four plastic bags with 5 g of sample in each animal were used in each treatment. Crude protein content of the residues in each period was calculated. Four heifers (2 grade Holsteins and 2 Zebu) of 220 kg average LW were used in the second experiment to evaluate the effect of ammonia on organic matter digestibility, structural carbohydrates and N disappearance from fibrous material in the rumen. Four plastic bags with 5 g of untreated and treated residues were introduced in the rumen . In the third experiment 8 Holstein bulls of 400 kg average LW were used in a completely randomized design with 2 treatments (untreated and treated) to evaluate the effect of ammonia on dry matter digestibility of leaves and sugar cane. Three plastic bags with 5 g of the fractions of various animals were employed. The ammonia treatment significantly increased (P<0.001) dry matter digestibility of leaves and sheaths and a significant quadratic (P < 0.001) relationship was obtained between dry matter digestibility and duration of the residue treatment. The values of crude protein (N x 6.25) were three times higher from the 10th day onwards increasing organic matter digestibility and hemicellulose in 14 percentage units and cellulose in 10 units. 90% of the total N increasing with the treatment, disappeared from the fibrous material during rumen digestion. The results indicate the favourable results attained when sugar cane harvest residues are treated with ammonia.