Table 5.
Effect of dietary supplementation of exogenous alpha-amylases (AMA) on rumen pH, volatile fatty acids, and ammonia nitrogen concentrations by lactating dairy cows
| Item | Control2 | RMD3 | Variance component4 | Bias | |||||
|---|---|---|---|---|---|---|---|---|---|
| N1 | Mean | STD | Effect size | P | Ω2 | τ2 | Funnel Test5 (P-value) |
I 2 (%) | |
| pH | 12 | 6.3 | 0.3 | −0.03 (−0.06,0.01) | 0.10 | 0 | 0 | 0.1 | 0 |
| Total VFA6 (mmol/L) | 16 | 111.9 | 45.6 | 0.86 (−4.56, 6.3) | 0.66 | 9.06 | 0 | 0.07 | 73.48 |
| Acetate (%) | 17 | 62.5 | 3.3 | −0.32 (−1.23,0.59) | 0.38 | 2.18 | 0 | 0.62 | 42.90 |
| Propionate (%) | 17 | 20.0 | 2.6 | 0.03 (−1.41,1.46) | 0.95 | 0.64 | 0 | 0.91 | 60.52 |
| Butyrate (%) | 17 | 13.4 | 1.9 | 0.14 (−0.65,0.93) | 0.55 | 0.27 | 0 | 0.73 | 43.48 |
| A:P ratio7 | 13 | 3.10 | 0.5 | −0.10(−0.42,0.23) | 0.41 | 0.15 | 0 | 0.38 | 73.59 |
| NH3−N (mg/dL) | 16 | 21.0 | 6.5 | 0.06(−0.78,0.91) | 0.84 | 0 | 0 | <0.01 | 71.63 |
Positive values in RMD indicate an increase by addition of AMA, whereas negative values in RMD indicate a decrease by addition of AMA respect to the control.
Total number of comparisons.
No AMA in the diet.
Raw mean difference (weighted) between control vs. AMA treatment.
Ω2 = between-studies-within-cluster variance component, τ2 = between-cluster variance component (Hedges et al., 2010; Fisher et al., 2017).
P-value for X2 (Q) test for heterogeneity; I2 = Proportion of total variation of size effect estimated due to heterogeneity.
Total volatile fatty acids.
Acetate:Propionate ratio.