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- Title
Effect of inhibition of methane synthesis on biohydrogenation in the presence or absence of protozoa in continuous culture.
- Authors
Karnati, S. K. R.; Ribeiro, C. V. D. M.; Sylvester, J. T.; Firkins, J. L.
- Abstract
Ruminal methanogenesis disposes reducing equivalents generated from anaerobic metabolism of sugars. Our objectives were to assess the role of protozoa in biohydrogenation (BH) of dietary unsaturated FA, and to determine if inhibition of methanogenesis increased BH. Four dual-flow continuous culture vessels were modified to retain protozoa and used in a 4 x 4 Latin square design; each experimental period was split into 10-d faunated or defaunated (DEF) sub-periods, each with 7 d of adaptation and 3 d of sampling. Once daily, the fermenters were fed 40 g of a 30:70 concentrate:forage diet containing either no additive, 4% animal-vegetable fat, bromoethanesulfonate (BES 250 μM, methane inhibitor), or monensin ( MON 2.5 μM). pH in the fermenters was not controlled and ranged between 6.2 and 6.7. The model included the fixed effects of period, treatment, and filter, and the random effect of fermenter. Means were compared using protected LSD. Digestibilities of OM and NDF were increased (P<0.05), whereas total VFA production decreased (P=0.05) by DEF. Methanogenesis was not affected by DEF, but acetate:propionate decreased (P<0.01) from 3.53 to 3.29 and molar proportions of butyrate (P=0.09), isobutyrate and isovalerate (P<0.01) increased by DEF. Dietary fat increased the flow (mg/day) of the trans (t) BH intermediates t10 and t11, and the effect was more pronounced by DEF (DEF x treatment interaction P<0.01). Because the same interaction persisted for the ratio of total t18:1/18:0, but there was no interaction for total t18:1/total unsaturated FA, DEF probably decreased the rate of the second step of BH. DEF increased VA more than it increased t10 18:1 in fat diets (interaction of VA/t10 ratio). The flow of CLA was unaffected by DEF or by treatments other than added fat. MON tended (P=0.07) to decrease methanogenesis, but increased isovalerate. MON did not affect flows of t10, t11, or total t18:1 FA. Protozoa increased BH intermediates possibly by stimulating lipolysis or the first step of BH or by inhibiting the second step of BH by influencing the bacterial community structure by selective predation.
- Subjects
METHANE as fuel; FIXED effects model; PROTOZOA; ANAEROBIC metabolism; MAGIC squares; METHANE
- Publication
Journal of Animal Science, 2006, Vol 84, p127
- ISSN
0021-8812
- Publication type
Article