Degradabilidade ruminal e balanço energético em vacas leiteiras a pasto suplementadas com torta de dendê

With the objective to verify the most appropriate level of palm kernel cake inclusion in the concentrate of dairy cows on pasture, 16 multiparous dairy cows crossbreed Gir and Holstein were used, with average weight of 436.6kg (±59.7) in latin square design, with the cows distributed in four Latin squares (4 x 4 simultaneous; four treatments x four periods x four animals in each treatment). Ruminal degradability and energy balance were evaluated under grazing conditions, supplemented with concentrate, containing levels of 0, 25, 50 and 75% of palm kernel cake. The values of fractions A, B and C in DM of palm kernel cake were 2.41, 66.65% and 0.0272 respectively. Potential and effective degradability of DM of palm kernel cake were: PD (69.06%) of ED 2%/h (40.84%) 5%/h (25.91%) and 8%/h (19.34%), fractions B and I, 66.65% and 30.94% respectively. Energy availability for lactation and net energy intake linearly decreased with palm kernel cake inclusion. Energy balance although positive was negative correlated to all levels of palm kernel cake inclusion. The best level of palm kernel cake inclusion is zero. However, in practice, it can be indicated the level of 25% of palm kernel cake in concentrate supplement for lactating cows on pasture, by the proximity of energy availability values with the most appropriate level (0% palm kernel cake).