The apparent dry matter digestibility (ADMD), apparent protein digestibility (APD), and apparent amino acid digestibility (AAAD) of thirteen feedstuffs used for marine shrimp diets were determined for the marine shrimp, Penaeus vannamei. The feedstuffs evaluated were casein, corn starch, gelatin, soy protein, wheat gluten, fish meal, rice bran, shrimp meal, soybean meal, squid meal, cellulose, chitin, and diatomaceous sand. Each feedstuff comprised 88% of the experimental diets. The ADMD values ranged from 91.4% to -21.4%.The purified feedstuffs were more efficiently digested than the practical feedstuffs. The dietary fillers (cellulose, chitin, and diato maceous sand) were either poorly digested or not digested.The APD values ranged from 99.1% to 3.0%. There were no differences in APD due to animal or plant feedstuff origin. The AAAD were determined for arginine, lysine, leucine, iso leucine, threonine, valine, histidine, phenylalanine, glutamate, aspartate, glycine, proline, serine, tryrosine, and alanine. The digestibility trends observed for APD were similar for AAAD. The high AAAD for chitin suggested that the low APD was due to the low digestibility of the amine fraction of the chitin structure and not a low protein digestibility. Arginine, lysine, and glutamate were most efficiently digested, while alanine had the lowest apparent digestibility value.
