title: Comparison of D-alanine and diaminopimelic acid as bacterial markers in young calves.
abstract: D-alanine (DAL) and diaminopimelic acid (DAP) were compared as markers to estimate proportion of bacterial N in total N reaching the abomasum of young calves. Sixteen Holstein bull calves fed complete pelleted starter or unpelleted starter plus hay and weaned at 4 or 8 wk of age were fitted with ruminal and abomasal cannulas and sampled twice weekly from 2 to 11 wk of age. Isolated ruminal bacterial cells contained more DAL than DAP at all weeks and averaged 7.0 and 5.4 mg N/g N, respectively. Weekly mean marker concentrations were highly correlated (.89) in ruminal bacteria, except at 3 wk of age. Concentration of DAL in abomasal digesta was greater than that of DAP at all weeks and averaged 5.2 and 2.4 mg N/g N, respectively. Weekly mean DAL correlated with DAP .61 in abomasal digesta and correlated .57 and .89 with starter intake, respectively. The proportion of bacterial N in total abomasal N was greater at all weeks when estimated by DAL than by DAP and averaged 77% and 46%, respectively. Estimates by DAL exceeded 100% in several cases and reflected large variation in analytical estimates. Estimates by DAL and DAP correlated .33 and .92 with starter intake. D-alanine was not an acceptable bacterial marker in this study.
authors: University of New Hampshire, Durham 03824.
authors: J D
authors: JD
authors: Quigley
authors: C G
authors: CG
authors: Schwab
mesh_terms: D000409:Alanine / Q000032:analysis*; D000599:Amino Acids, Diamino / Q000032:analysis*; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D003960:Diaminopimelic Acid / Q000032:analysis*; D005766:Gastrointestinal Contents / Q000032:analysis*; D007422:Intestines / Q000382:microbiology*; D008297:Male; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*
chemical_list: D000599:Amino Acids, Diamino; D003960:Diaminopimelic Acid; D009584:Nitrogen; D000409:Alanine