Determination of digestibilities of amino acids of soybean meal and sesame meal using caecectomized roosters

The apparent and true amino acid digestibilities of two vegetable protein sources were determined using adult caecectomized roosters. The test ingredients were soybean meal and sesame meal. Each test ingredient was offered to six caecectomized and six intact roosters individually. The apparent digestibilities of cystine, lysine, threonine, arginine, serine, aspartic acid and glutamic acid and true digestibilities of most of the amino acids of soybean meal were higher (P<0.01 to 0.001) in intact cockerels. On the contrary, the apparent as well as true digestibilities of all the 16 amino acids of screw pressed sesame meal were higher (P<0.001) in caecectomized roosters. The intact cockerels overestimated the amino acid digestibilities of soybean meal and underestimated those of sesame meal. These results revealed that the caecal microbial population played a pivotal role in altering the amino acid composition of digesta entering and leaving the large intestinal segment.