Table 2.
Descriptive statistics of the parameters included in the meta-analysis.
| Parameter 1 | Studies | Minimum | Maximum | Mean | Median | SD |
|---|---|---|---|---|---|---|
| Treatment duration (d) | 22 | 22.0 | 427 | 143 | 80.5 | 125.0 |
| Days in milk (d) | 14 | 20.0 | 296 | 171 | 183 | 60.16 |
| DMI (kg/d) | 16 | 15.6 | 27.4 | 21.4 | 22.4 | 3.547 |
| Milk yield (kg/d) | 23 | 18.2 | 49.2 | 31.0 | 30.1 | 6.559 |
| Milk Fat (%) | 16 | 3.32 | 4.80 | 4.03 | 3.92 | 0.445 |
| Milk protein (%) | 16 | 2.79 | 3.51 | 3.25 | 3.29 | 0.190 |
| Milk lactose (%) | 8 | 4.43 | 5.27 | 4.75 | 4.76 | 0.206 |
| Milk SCC (log/mL) | 3 | 3.91 | 4.92 | 4.46 | 4.63 | 0.429 |
| FPCM yield (kg/d) | 20 | 21.3 | 47.1 | 32.9 | 32.1 | 5.957 |
| FCE (kg/kg) | 16 | 1.17 | 1.97 | 1.52 | 1.48 | 0.207 |
| Rumen pH | 3 | 6.46 | 6.78 | 6.62 | 6.62 | 0.147 |
| Total VFA (mmol/L) | 8 | 50.8 | 165 | 103 | 101 | 29.56 |
| Acetate (%) | 7 | 57.7 | 76.5 | 66.3 | 66.8 | 6.252 |
| Propionate (%) | 7 | 14.9 | 26.0 | 19.3 | 18.4 | 3.630 |
| Butyrate (%) | 7 | 8.74 | 14.1 | 10.9 | 10.0 | 1.931 |
| Protozoa (log cells/mL) | 3 | 5.00 | 5.80 | 5.43 | 5.52 | 0.333 |
| CH4 production (g/d) | 8 | 229 | 445 | 321 | 291 | 78.86 |
| CH4 yield (g/kg DMI) | 8 | 9.79 | 46.2 | 19.7 | 17.0 | 10.75 |
| CH4 intensity (g/kg FPCM) | 8 | 6.66 | 17.2 | 12.2 | 13.3 | 3.310 |
1 DMI, dry matter intake; SCC, somatic cell counts; FPCM, fat and protein corrected milk; FCE, feed conversion efficiency; VFA, volatile fatty acids.