Table 1.
Summary of statistics of regressors and response variables.
| Variable | N | Number of experiments | Mean | SDb | Range |
|---|---|---|---|---|---|
| N (%DM)a | 137 | 44 | 2.33 | 0.54 | 0.8–3.51 |
| Concentrate (%DM) | 141 | 46 | 43.6 | 24.0 | 0–90.5 |
| NDF (%DM) | 109 | 33 | 40.5 | 11.4 | 19.2–76.5 |
| CH4 (L/d) | 163 | 54 | 168 | 178 | 0–744 |
| CH4/DMI (L/kg MS) | 151 | 49 | 23.3 | 10.1 | 0–44.8 |
| DMI (kg/d)c | 83 | 25 | 10.8 | 6.89 | 0.99–28 |
| ECM (kg/d) | 26 | 10 | 27.6 | 10.8 | 1.17–46.2 |
| ECM/DMI (kg/kg DM) | 26 | 10 | 1.41 | 0.17 | 1.14–1.81 |
| BMG (kg/d) | 38 | 13 | 0.75 | 0.44 | 0.022–1.55 |
| BMG/DMI (kg/kg DM) | 38 | 13 | 0.11 | 0.044 | 0.025–0.17 |
| DMD (%) | 46 | 17 | 68.6 | 4.48 | 56.8–76.4 |
| DMf (kg/d) | 44 | 16 | 6.91 | 6.09 | 0.46–19.8 |
| OMD (%) | 37 | 13 | 71.1 | 3.98 | 62–79.2 |
| OMf (kg/d) | 30 | 10 | 9.11 | 5.37 | 0.44–18.5 |
| ND (%) | 38 | 14 | 69.1 | 7.28 | 53.4–82.9 |
| Nf (kg/d) | 34 | 12 | 0.20 | 0.17 | 0.019–0.49 |
| NDFD (%) | 34 | 12 | 53.8 | 8.30 | 30.7–64.9 |
| NDFf (kg/d) | 34 | 12 | 2.50 | 1.16 | 0.18–4.84 |
| EF (MJ/100 MJ GEI) | 44 | 17 | 29.5 | 4.79 | 14.1–35 |
| EF (MJ/d) | 31 | 12 | 27.0 | 29.0 | 1.56–89.9 |
| H2 (L/d) | 54 | 15 | 37.6 | 78.3 | 0–193 |
| H2 (MJ/d) | 38 | 9 | 0.41 | 1.04 | 0–2.26 |
| EG (MJ/100 MJ GEI) | 18 | 6 | 5.28 | 1.57 | 2.7–8.4 |
| EG (MJ/d) | 38 | 9 | 9.67 | 7.46 | 0.34–27.1 |
| UE (MJ/100 MJ GEI) | 36 | 14 | 3.70 | 1.33 | 1.20–6.4 |
| UE (MJ/d) | 29 | 11 | 2.89 | 2.69 | 0.19–8.7 |
| HP (MJ/100 MJ GEI) | 21 | 8 | 42.6 | 9.76 | 27.7–61.8 |
| HP (MJ/d) | 21 | 8 | 53.7 | 48.1 | 5.49–138 |
| Rumen pH | 50 | 17 | 6.50 | 0.32 | 5.5–7.33 |
| Rumen total VFA (mM) | 86 | 30 | 89.8 | 24.9 | 47.5–161 |
| Acetate (mM) | 86 | 30 | 55.3 | 15.4 | 31–99.2 |
| Propionate (mM) | 86 | 30 | 18.2 | 6.42 | 6.49–38.5 |
| Butyrate (mM) | 86 | 30 | 10.9 | 4.31 | 4.73–23.5 |
| Isobutyrate (mM) | 54 | 18 | 1.69 | 1.52 | 0.48–7.46 |
| Valerate (mM) | 63 | 22 | 2.01 | 1.22 | 0.36–6.04 |
| Isovalerate (mM) | 59 | 20 | 2.04 | 1.12 | 0.12–4.76 |
| Acetate/propionate (mM/mM) | 67 | 24 | 3.32 | 0.90 | 1.95–6.1 |
| (mM) | 65 | 22 | 9.65 | 7.66 | 1.64–30 |
| Bacteria (log10 16S rRNA gene copies/g rumen contents) | 27 | 10 | 10.4 | 1.55 | 7.03–12.5 |
| Protozoa (log10 18S rRNA gene copies/g rumen contents) | 25 | 9 | 6.44 | 2.76 | 1.46–12.0 |
| Methanogens [log10 (16S rRNA + mcrA) gene copies/g rumen contents] | 27 | 10 | 7.92 | 2.28 | 2.47–11.9 |
a
BMG, bodymass gain; CH4, methane; DM, dry matter; DMD, dry matter digestibility; DMf, dry matter output in feces; DMI, dry matter intake; ECM, energy-corrected milk; EF, energy output in feces; EG, energy output in gases; GEI, gross energy intake; H2, dihydrogen; HP, heat production; N, nitrogen; ND, nitrogen digestibility; NDF, Neutral detergent fiber; NDFD, neutral detergent fiber digestibility; Nf, nitrogen output in feces; , ammonium; OMD, organic matter digestibility; OMf, organic matter output in feces; UE, urine energy; VFA, volatile fatty acids.
b
Standard deviation.
c
Only experiments with ad libitum feeding considered.