Northern Prairie Wildlife Research Center

# Urinary 3-methylhistidine and Progressive Winter Undernutrition in White-tailed
Deer

## Results

Temporal patterns of urinary 3-methylhistidine in the treatment group differed
significantly from those of the controls (F_{2,46} = 10.90; *P*
< 0.0001). Initially, 3-methylhistdine:creatinine ratios of controls versus
treatment deer were not significantly different (**Fig. 1;** H_{0}:
equal intercepts, F_{1,5} =1.46; *P* = 0.280). However, whereas
values in the controls remained nearly constant through time (H_{0}:
β_{1} = 0, T_{46}
= 0.86, *P* = 0.392; H_{0}: β_{2}
= 0, T_{46} = 1.50, *P* = 0.140), 3-methyhistidine: creatinine
values of treatment deer exhibited a marked increase by 31 March (**Fig.
1;** H_{0}: β_{1}
= 0, T_{46} = 2.42, *P* = 0.018; H_{0}: β_{2}
= 0, T_{46} = 4.42, *P* < 0.0001).
Similarly, a significant curvilinear relationship was observed between 3-methylhistidine:
creatinine and progressive percent mass loss in the seven deer (**Fig.
2;** H_{0}: β_{0}
= 0, T_{6} = -0.06, *P* = 0.951; H_{0}: β1
= 0, T_{41} = 1.42, *P* = 0.162; H_{0}: β2
= 0, T_{41} = - 2.53, *P* = 0.015; H_{0}: β3
= 0, T_{41} = 4.29, *P* = 0.0001; *R*^{2} = 0.82).
The single observation with 32% mass loss (solid triangle, **Fig. 2**)
was excluded from the regression analysis. This deer was near death and was
the only animal to experience >29% mass loss during the study. This deer's
final 3-methylhistidine:creatinine ratio did not adhere to the general trend
of values and may have been reflective of a breakdown of "normal" physiological
processes as it approached death. Until more data are available for such extreme
mass loss, we think it prudent to limit statistical inference to the range
of mass loss values ≤ 29%.

The 3-methylhistidine:creatinine ratios were strongly related (*r*^{2}
= 0.89) to urea nitrogen:creatinine ratios (**Fig.
3**). Short-term (4 days) acute, severe nutritional restriction had
a minimal effect on urinary 3-methylhistidine:creatinine values in control
deer, but it had a dramatic effect on the ratios of the treatment deer (**Table
1**).

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