ISOALDEHYDEDIUREAS AS NONPROTEIN NITROGEN SOURCES FOR RUMINANT ANIMALS

In experiments designed to evaluate isovaleridenediurea (IVDU; butanal, 3-methyl-di-urea) as a nonprotein nitrogen supplement for ruminant animals IVDU and isobutylidenediurea (IBDU; propanal, 2-methyl-di-urea) were compared to urea. Ammonia concentrations were increased (P < 0.05) by 2–5 mM when IBDU or IVDU were added to an in vitro incubation medium in comparison with up to 24 mM when equal amount of urea nitrogen was used. Isobutyric and isovaleric acid concentrations in the incubation medium were higher (P < 0.05) when IBDU and IVDU, respectively, were present. In an in vivo experiment, ammonia concentrations were reduced (P < 0.05) from 7.0 to 4.7 mM at 0.5 h after feeding when a mixture of 6 g IBDU and 6 g IVDU was substituted for 6.8 g urea in the diet of four sheep fed 1200 g hay and 100 g concentrate daily in a crossover experimental design. No differences (P > 0.05) in isobutyric or isovaleric acid concentrations in the rumen fluid were observed between treatments. Apparent digestibilities were not influenced by diet. It was concluded that although IVDU and IBDU had potential as nonprotein nitrogen supplements, degradation rates of both compounds were low and excessive amounts of the compounds may escape from the rumen undegraded. Key words: Sheep, isobutylidenediurea, isovaleridenediurea, nonprotein nitrogen supplements, in vitro, in vivo