Six plant sources of hydrolyzable tannins (HT) or HT and condensed tannins (CT; designated as HT1, HT2, HT3, HT + CT1, HT + CT2, and HT + CT3) were evaluated to determine their effects in vitro on CH(4) production and on ruminal archaeal and protozoa populations, and to assess potential differences in biological activities between sources containing HT only or HT and CT. Samples HT1, HT2, and HT3 contained only HT, whereas samples HT + CT1, HT + CT2, and HT + CT3 contained HT and CT. In experiment 1, in vitro incubations with samples containing HT or HT + CT resulted in a decrease in CH(4) production of 0.6 and 5.5%, respectively, compared with that produced by incubations containing the added tannin binder polyethylene glycol-6000. Tannin also suppressed the population of methanogenic archaea in all incubations except those with HT2, with an average decrease of 11.6% in HT incubations (15.8, 7.09, and 12.0 in HT1, HT2, and HT3) and 28.6% in incubations containing HT + CT (35.0, 40.1, and 10.8 in HT + CT1, HT + CT2, and HT + CT3) when compared with incubations containing added polyethylene glycol-6000. The mean decrease in protozoal counts was 12.3% in HT and 36.2% in HT + CT incubations. Tannins increased in vitro pH, reduced total VFA concentrations, increased propionate concentrations, and decreased concentrations of iso-acids. In experiment 2, when a basal diet was incubated with graded levels of HT + CT1, HT + CT2, and HT + CT3, the total gas and CH4 production and archaeal and protozoal populations decreased as the concentration of tannins increased. Our results confirm that tannins suppress methanogenesis by reducing methanogenic populations in the rumen either directly or by reducing the protozoal population, thereby reducing methanogens symbiotically associated with the protozoal population. In addition, tannin sources containing both HT and CT were more potent in suppressing methanogenesis than those containing only HT.

No abstract

No abstract

The aim of this experiment was to determine CH4 production and energy partition for a range of diets fed to Bos indicus cattle. Six Brahman cattle were fed on three different diets in a replicated Latin square experiment over three periods. The diets were (1) long-chopped Angleton grass (Dicanthium aristatum) hay ad libitum (DM digestibility (DMD) 41 (se 2)%; 4 g N/kg), (2) long-chopped Rhodes grass (Chloris gayana) hay ad libitum (DMD 60 (se 1)%; 14 g N/kg) or (3) 2 kg long-chopped lucerne (Medicago sativa) hay/d plus a high-grain diet (ad libitum) (DMD 70 (se 1)%; 31 g N/kg). CH4 production was measured using confinement-type respiration chambers. Metabolizable energy intake (MJ/d) of cattle fed on Angleton grass (18·4 (se 2·0)) was lower (P< 0·01) than that for Rhodes grass (54·9 (se 2·1)), which was lower (P< 0·01) than that for the high-grain diet (76·7 (se 5·8)). CH4 production (g/d) for cattle fed on Rhodes grass (257 (se 14)) was higher (P< 0·01) than that for cattle fed on both the high-grain diet (160 (se 24)) and Angleton grass (113 (se 16)). CH4 conversion rate (MJ CH4 produced per 100 MJ gross energy intake) was not significantly different between cattle fed on Angleton (10·4 (se 1·1)) and Rhodes (11·4 (se 0·3)) grass, but was higher (P< 0·01) than for cattle fed on the high-grain diet (6·7 (se 0·7)). CH4 production (g/kg live-weight gain) was associated (P< 0·001) with both live-weight gain and feed: gain ratio. We conclude that the relationships between CH4 production, energy utilization and live-weight change of cattle fed on tropical forages differ from those of cattle fed on diets based on temperate forages.

The relationship between dry matter intake (DMI) and methane (CH4) production was investigated using results obtained from 190 energy balance trials with dairy cattle, beef cattle, sheep and goats to predict total methane emission from livestock in Japan.The results were as follows : 1) CH4 production per unit of feed intake decreased as feeding level increased although the absolute amount of CH4 production (X, kg/day) can be expressed as a quadratic form. The equation best fitted to the data for all aminals was Y=-17.766+42.793X-0.849X2 (r=0.966).3) From the estimation equation, average dry matter intake and cattle populations, annual CH4 production was estimated to be 0.182 teragrams (Tg) from dairy cattle and 0.150Tg from beef cattle.Total CH4 emission from ruminant livestock in Japan was estimated to be 0.332 Tg/year, and total CH4 emission from all livestock including ruminants, pigs and horses was 0.345 Tg/year in Japan. This only accounts for around 0.5% of total CH4 emissions from animals all over the world.