The objective of this study was to determine the effect of feeding two fermented total mixed ration (FTMR) on methane production in dairy heifers. Four Holstein Friesian dairy heifers with mean body weight (BW) of 301.1 ± 42.2 kg were used in a simple cross-over design trial. Treatments consisted of 2 FTMR formulated to yield either low (LMD) or high CH 4 production (HMD). No differences were observed in dry matter intake (DMI; 6.49 and 6.19 kg/d), BW change (-3.37 and -7.25 kg), or DM digestibility (50.64 and 46.99%) between diets. Ruminal pH, total volatile fatty acids (TVFA) and molar proportions of acetate, propionate and butyrate were not different among diets. Concentrations of blood glucose were higher (P=0.05) for HMD compared with LMD at 2 h post feeding; however, blood urea nitrogen was not different. Methane emissions were 236.32 L/d for LMD and 273.70 L/d for HMD and not different. Feeding the FTMR differing in CH 4 potential did not affect DMI, digestibility, ruminal TVFA production or molar proportions of VFAs in dairy heifers.

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