Dry matter was determined by oven drying at 105 °C overnight
(AOAC, cod. 930.15, 1995). Crude protein was measured by a Kjeldahl
nitrogen analysis (AOAC cod. 954.01, 1995). Ash content was determined
by combusting for 3 h at 550 °C. Neutral detergent fiber
(NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL)
content were determined according to Van Soest, Robertson, and
Lewis (1991). Lipids were extracted by diethyl ether using a Soxhlet
apparatus.