K.D. Kerr L.D. Mech M.R. Riggs U.S. Seal G. D. DelGiudice 1998 <div>Physiological indicators of muscle catabolism would aid assessment of winter nutritional restriction of ungulates, and urinary 3-methylhistidine has exhibited potential in this regard in several species. We examined the effect of chronic moderate and severe nutritional restriction during winter on urinary 3-methylhistidine:creatinine ratios in seven adult white-tailed deer (<i>Odocoileus virginianus</i>) and the relationship of these ratios to urinary urea nitrogen:creatinine ratios. Mean base line estimates of urinary 3-methylhistidine:creatinine ratio for the control and severely restricted deer (0.043 and 0.086 µmol:mg, respectively) were similar (<i>P</i><span>&nbsp;</span>= 0.280) and remained unchanged in the control deer throughout the study. In contrast, mean 3-methylhistidine:creatinine ratios increased dramatically as nutritional restriction and cumulative mass loss progressed; the quadratic component of the data for the chronically restricted deer was significant (<i>P</i><span>&nbsp;</span>&lt; 0.001). Likewise, there was a strong curvilinear relationship (<i>R</i>²<span>&nbsp;</span>= 0.82) between cumulative mass loss (up to 29%) of the pooled deer and urinary 3-methylhistidine:creatinine ratios. Further, urinary urea nitrogen:creatinine ratios were strongly related to 3-methylhistidine:creatinine ratios (<i>r</i>²<span>&nbsp;</span>= 0.89). Our study indicates that further investigation of 3-methylhistidine as an indicator of physical condition and muscle protein breakdown is warranted.</div> application/pdf 10.1139/z98-148 en Canadian Science Publishing Urinary 3-methylhistidine and progressive winter undernutrition in white-tailed deer article