Submitted to: Grassland International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 11, 2001
Publication Date: February 11, 2001
Interpretive Summary: Leucaena is a tropical browse legume that has proved useful in livestock production systems because of its high nutritive value (crude protein and digestibility) and persistence. The presence of a toxic nonprotein amino acid, mimosine, which is converted by ruminal microorganisms to a goitro- genic compound limited utilization of leucaena diets. Leucaena can be detoxified when animals are colonized with a unique rumenal bacteria, Synergistes jonesii. This bacteria should allow leucaena to be safely used to feed ruminants, such as giraffe, in zoological parks. Rumen fluid and fecal cultures can be used to determine the presence of the bacteria, but fecal culture is the best method for use with zoological ruminants because of ease of sample collection. Because the bacteria starts to die when ex- posed to air, we looked at the effect of time post collection and storage temperatures to see if current fecal culture methods could be used with older samples. This study showed that temperatures had relatively little effect on the detection frequency of the bacteria, but detection frequency declined with storage time and indicates relatively fresh (<6 h old) fecal sample should be used.
Synergistes jonesii is a rumen bacterium that degrades 3, 4- dihydroxpyri- dine (3,4 DHP), the toxic breakdown product of mimosine in leucaena (Leucaena leucocephala). Fecal culture is the most practical way to deter- mine S. jonesii presence in zoological ruminants, particularly if feces can be collected from night penning facilities. Fresh rumen fluid and fecal or fecal slurry (sheep [Ovis spp.] only, 1:4 wt to vol. feces and culture media) from cattle (Bos spp.) and sheep, known to be colonized by S. jonesii, were subjected various storage times (0,6,12, and 24 h) and temp- eratures (5,23, and 30 C). Samples were inoculated into a culture medium that contained 3,4 DHP. In general, storage temperature had no effect on detection frequency. Regardless of species, detection of S. jonesii was higher (P=0.001) in rumen (97%) than fecal (40%) samples and level of de- tection in rumen samples was relatively unaffected by time. Detection fre- quency was similar for both fecal sample types regardless of time (34% fecal vs. 29% fecal slurry). For all fecal samples, detection frequency generally exhibited a linear decline (P=0.01) with time. This study showed that it will be important to collect fresh fecal samples (<6 h old) from night penning facilities.