The objective of this work was to determine the digestible (DE) and metabolizable (ME) energy values of some feeds for weaned pigs. Fourteen feeds were evaluated in five experiments, using 144 piglets with an average initial weight of 9.42+0.76 kg at 28 days of age. The DE and ME contents were determined by means of the total collection of feces and urine method. The protein sources from milk had higher energy and protein digestibility than soybean by products. Among these, concentrated protein and textured protein had the highest energy digestibility, and full fat extruded soybean had the smallest. The dry matter and energy digestibility values obtained for corn and soybean meal with 46.5% crude protein were similar to the values obtained for adults pigs, indicating that the capacity of piglets to digest these two feeds did not differ from adults swine. There was a reduction in the ME/DE ratio with increasing protein levels and with unbalance among dietary amino acids. The gross energy to N excreted in the urine ratio was reduced when dietary protein was increased and vices versa. These data indicate the need to determine a correction factor for the EM values, specific to the different groups of feeds and experimental conditions.
digestibility; metabolism; swine
