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Table 4 Urinary nitrogen, purine derivatives (PD), and estimated microbial protein (MCP) supply to the dairy cows fed 3 experimental diets

From: Effects of the dietary nonfiber carbohydrate content on lactation performance, rumen fermentation, and nitrogen utilization in mid-lactation dairy cows receiving corn stover

Itemsd Treatmentc SEM P-value
AH L-NFC H-NFC
Urine volume, L/d 34.3a 32.7a 28.6b 1.52 0.02
Urinary PD, mmol/d
 Allantoin 358 377 325 22.0 0.26
 Uric acid 60.8 59.2 52.7 4.97 0.22
 Endogenous PD 52.6 52.7 52.5 1.28 0.68
MCP, g/d 1690 1766 1516 117 0.31
Urea nitrogen, mg/dL 670 730 664 30.1 0.09
  1. a-b Least squares means within a row with different superscripts differ significantly (P < 0.05)
  2. cAH = Total mixed rations containing alfalfa hay; L-NFC = Total mixed rations containing corn stover with a low content of non-fiber carbohydrates; H-NFC = Total mixed rations containing corn stover formulated to have similar non-fiber carbohydrate concentrations as the AH diet
  3. dUrine volume (L/d) = BW (kg) × 29 (mg/d)/creatinine (mg/L) [18]; Microbial protein (MCP) was indirectly estimated by the following eq. [15]: MCP = (allantoin + uric acid − endogenous PD) × 70 × 6.25/(0.116 × 0.83 × 1000)