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979
Use of crystalline amino acids in meal feeding does not affect nitrogen retention in growing pigs compared to protein-bound amino acids
The present study was conducted to test the hypothesis that the supplementation of crystalline AA (CAA) affects the N retention for growing pigs in the meal feeding. Ten pigs with initial BW of 53.6 kg (SD = 2.7) were individually housed in metabolism crates. The pigs were allotted to 2 experimental diets according to a cross-over design with 10 animals and 2 periods. Two experimental diets were formulated. A diet was mainly based on corn and soybean meal as N sources (protein-bound form-diet, PBD), and the CAA were supplemented to the PBD at the expense of 14.2% soybean meal (CAA-supplemented diet, CD). The supplementation levels of CAA were determined based on the standardized ileal digestible AA in the SBM. The daily amount of feed allowance per pig was determined as 3 times the maintenance energy of pigs within similar BW and an equal amount of the feeds was provided at 0730 and 1630 h. Total but separate collection of feces and urine was performed according to marker-to-marker and time-to-time methods, respectively. The amounts of excreted and retained N were determined based on the analyzed N contents in the fecal and urinary samples. Nitrogen intake of pigs fed the PBD and CD were 52.4 and 46.2 g/d (P < 0.001), respectively. The fecal N excretion (7.52 and 6.23 g/d, P = 0.014), digested N (44.9 and 39.9 g/d, P < 0.001), and retained N (24.9 and 22.2 g/d, P = 0.014) in the pigs fed the PBD were greater than in the pigs fed the CD. However, the apparent total tract digestibility of N and retention of N did not differ among the pigs fed 2 experimental diets. In conclusion, the use of CAA in the meal feeding did not affect the N retention in growing pigs compared to the protein-bound AA from the SBM.
Keywords:
free amino acid, nitrogen retention, protein-bound amino acid