Table 1 Dry matter intake, milk yield, and apparent nitrogen balance in low and high nitrogen efficient Holstein cows.

From: Bacterial community structure in the rumen and hindgut is associated with nitrogen efficiency in Holstein cows

Item1

Phenotype

P-value

Low Neff (n = 6)

High Neff (n = 5)

DMI, kg/day

27.8 ± 1.24

25.7 ± 1.36

0.27

Milk yield, kg/day

32.8 ± 1.36

39.4 ± 1.49

< 0.01

 Protein, %

3.11 ± 0.08

2.98 ± 0.08

0.27

 Fat, %

3.99 ± 0.17

3.68 ± 0.19

0.26

 SCC, cells/mL

53.5 ± 2.81

62.6 ± 3.08

0.06

N balance, g/day

 N intake

713 ± 31.6

658 ± 34.6

0.27

 Milk N

162 ± 9.65

199 ± 10.57

0.03

 Urinary N

222 ± 15.1

212 ± 16.6

0.68

 Fecal N

245 ± 12.9

219 ± 14.1

0.20

 Manure N

467 ± 21.7

431 ± 23.8

0.29

 Retained N

83.1 ± 23.4

27.9 ± 25.7

0.15

N, g of N/kg of milk

 Urinary N

6.76 ± 0.39

5.39 ± 0.42

0.04

 Fecal N

7.54 ± 0.36

5.56 ± 0.40

 < 0.01

 Manure N

14.3 ± 0.54

11.0 ± 0.59

 < 0.01

Neff, %

22.8 ± 0.83

30.3 ± 0.91

 < 0.01

  1. 1Values expressed as mean ± SEM.
  2. DMI dry matter intake, SCC somatic cell count
  3. Manure N = urinary N + fecal N.
  4. Retained N = \({\text{N}}\;{\text{intake }} - ({\text{milk}}\;{\text{N}} + {\text{manure }}\;{\text{N}})\).
  5. N efficiency (Neff) = \(({\text{milk }}\;{\text{N}}\;({\text{g/d}}){\text{/N}}\;{\text{intake}} \;({\text{g/d}})) \times 100\).
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