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.