Table 3. Rumen fermentation characteristics of Holstein and Jersey steers with different levels of mineral supplementation
Parameters | Holstein | Jersey | SEM | Mixed p-value |
Con | NM | HM | Con | NM | HM | Breed | Treat | B × T |
pH | 6.98 | 7.18 | 7.11 | 6.85 | 6.94 | 6.93 | 0.091 | 0.044 | 0.340 | 0.865 |
NH3-N (mg/dL) | 4.18c | 5.01a | 4.82b | 4.25y | 4.42y | 5.48x | 0.035 | 0.228 | < .0001 | < .0001 |
Total VFA (mmol/L) | 66.95 | 68.78 | 67.09 | 86.89 | 89.32 | 89.34 | 2.516 | < .0001 | 0.781 | 0.924 |
Acetate (%) | 57.52 | 61.37 | 56.20 | 56.94 | 57.81 | 55.18 | 0.928 | 0.135 | 0.049 | 0.466 |
Propionate (%) | 26.23 | 22.79 | 24.06 | 25.85 | 23.53 | 23.89 | 1.359 | 0.967 | 0.315 | 0.945 |
Butyrate (%) | 16.25 | 15.84 | 19.74 | 17.21 | 18.66 | 20.93 | 1.471 | 0.305 | 0.178 | 0.857 |
A:P | 2.23 | 2.69 | 2.34 | 2.21 | 2.46 | 2.34 | 0.129 | 0.584 | 0.213 | 0.765 |
Con, only TMR (without mineral supplementation); NM, TMR + NRC recommended concentration of mineral supplementation (Se 0.1 ppm + Zn 30 ppm + Cu 10 ppm)/kg DM; HM, TMR + higher than recommended concentration of mineral supplementation (Se 3.5 ppm + Zn 350 ppm + Cu 28 ppm)/kg DM; B, breed effect; T, trace mineral supplementation effect; B × T, interaction effect between breed and trace mineral supplementation.
Means with different superscripts in a row differ significantly among different treatment groups in Holstein steers while
Means with different superscripts in a row differ significantly among different treatment groups in Jersey steers (p < 0.05).
A:P, acetate: propionate; NH3-N, ammonia-nitrogen; VFA, volatile fatty acid; TMR, total mixed rations; NRC, National Research Council; DM, dry matter.