Efeitos de níveis e de tempos de adaptação a lasalocida sódica sobre a degradabilidade ruminal do feno de Coast-cross (Cynodon dactylon) e do farelo de soja em bovinos

The objectives of the present study were to determine the effects of time of adaptation and different levels of sodium lasalocid on soybean meal dry matter and crude protein degradability on Coast Cross hay (Cynodon dactylon) dry matter and neutral detergent fiber degradability. Experimental design used was a 4 x 4 Latin Square with repeated measures on time using four rumen cannulated cows, with an average live weight of 500 kg. The experiment was conducted in subperiods of 42 days, divided in 28 days for data collection and 14 days for eliminating the carry over effects of treatments. Diets were formulated using coast-cross hay (82 % NDF and 8 % CP) and concentrate (8.5 % soybean meal, 41 % ground corn and 0.5 % of mineral supplement) in a proportion of 1:1. Treatments arrangements included four different adaptation times (0 to 7, 8 to 14, 15 to 21 and 22 to 28 day) and four levels of sodium lasalocid per animal per day (zero, 50 mg, 100 mg and 200 mg). No level effects were observed on Coast-Cross hay DM and NDF effective degradability and on soybean meal DM and CP effective degradability . Effective degradability was not affected by treatment X time interaction, however sodium lasalocid levels showed a quadratic effect (P<0.05) on NDF potential degradability, with the lowest values of the potential degradability for the 100 mg level. The low quality of Coast-Cross hay used (CP=8 %) may be the main cause why DM and NDF degradability were not affected by sodium lasalocid. Based on results obtained in this study it can be concluded that sodium lasalocid does not alter the effective degradability of CP soybean meal nor the effective degradability of NDF of coast-cross hay.