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The purpose of this study was to determine the effect of different crude protein (CP) levels and protease (PT) supplementation on effect in weaned pigs. A total of 24 barrow weaned pig, 7-week-old and with an initial weight of 10.94 ± 1.26 kg, were performed in the 2-week experiment. The experiment followed a 2 × 2 factorial design with two levels of CP (18.78% and 16.92%) and two levels of PT supplementation (0, 0.1%). No difference was observed in growth performance by the variations in CP and PT levels. In fecal score, the low CP (LP) diet showed an increased frequency of 0 scores compared to the high CP (HP) diet. The apparent total tract digestibility (ATTD) of dry matter (DM) increased during the first week in the LP diet compared to the HP diet. At second week, the ATTD of DM was increased in the LP diet compared to the HP diet and the ATTD of CP increased in the PT10 compared to the PT0. Also, DM had an interaction between CP and PT. In the ATTD of amino acids in the first week, the LP diet had a higher methionine digestibility than the HP diet, and the tryptophan digestibility was higher in the HP diet than the LP diet. In second week, the PT10 diet had a higher digestibility than the PT0 diet for indispensable amino acids excluding lysine and tryptophan, and for methionine, the LP diet had a higher digestibility than the HP diet. In the ATTD of indispensable amino acids, the digestibility of threonine, isoleucine, leucine, arginine, and methionine was higher in the PT10 diet compared to the PT0 diet. Blood urea nitrogen (BUN) and hydrogen sulfide (H2S) gas emissions were decreased in the LP diet and PT10 compared to HP and PT0. In the nitrogen utilization, total excretion decreased in the LP and PT10 compared to HP and PT0, and the nitrogen retention ratio increased at second week. In this study, supplementation of PT in the LP diet can improve weaned pig's fecal score, nutrients digestibility, BUN, H2S emission, and nitrogen utilization in weaned pigs.
An et al. (Wed,) studied this question.