Effects of different non-protein amino acids on in vitro dry matter digestibility of lucerne chaff

Some plants not only contain various nutrients which support the growth of animals, but also contain anti-nutritional factors which have adverse effects on animals. NPAAs, such as ODAP and DABA, are among those compounds. In addition to the direct adverse effects on animals by NPAAs, studies also have shown that ODAP, a major non-protein amino acid in some forage legumes, inhibited the growth of some non-ruminal microorganisms. Experiments were conducted to determine the effects of ODAP and DABA on in vitro dry matter (DM) digestibility of lucerne chaff as means to test their effects on ruminal microorganisms. The results showed the in vitro DM digestibility of lucerne chaff at 24, 48 and 72 h was significantly reduced by 18.6, 11.0 and 8.6% when three levels of ODAP (40.67, 81.34 and 122 μg/ml, C18 reverse phase chromatography-fractionated extracts from L. sativus) were included in the medium. No inhibitory effect of diaminobutyric acid on in vitro DM digestibility of lucerne chaff was observed when pure DABA was used at a concentration of up to 300 μg/ml. The results indicated that although ODAP and DABA are similar in structure, they have different effects on ruminal organisms. Therefore, the use of DABA-containing plants as a feed supplement is not likely to cause any adverse effect on feed utilization, whereas the use of ODAP-containing plants may have some adverse effects on feed digestibility.