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In vitro fermentation patterns and methane production as influenced by cultivar and season of harvest of Lolium perenne L.
Author(s) -
Lovett D. K.,
McGilloway D.,
Bortolozzo A.,
Hawkins M.,
Callan J.,
Flynn B.,
O'Mara F. P.
Publication year - 2006
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/j.1365-2494.2006.00500.x
Subject(s) - lolium perenne , cultivar , perennial plant , ruminant , pasture , agronomy , growing season , biology , grazing , dry matter , zoology , chemistry
In some European countries, the majority of annual enteric methane (CH 4 ) emissions by ruminants occur at pasture – a direct result of the predominance of grazing within ruminant production systems. However, there are only limited data available as to the effect of perennial ryegrass cultivar and season of harvest on CH 4 production. Using the in vitro gas production technique, the effect of perennial ryegrass cultivar on fermentation characteristics and CH 4 production was determined (Experiment 1) and the persistence of these traits throughout the growing season for two cultivars, identified from Experiment 1 as having either a high or low methanogenic potential, was examined (Experiment 2). In Experiment 1, organic matter (OM) digestibility and cumulative total gas production profiles were unaffected by cultivar but, with regard to the kinetics of CH 4 production, the asymptote value ( A ), cumulative CH 4 yield at 72 h, and the fractional rate ( μ ) of CH 4 production at both time of 0·5 A ( T )( μ CH 4 T ) and at 48 h ( μ CH 4 48h) were significantly ( P < 0·05) different. The amount of digested OM, as a proportion of cumulative CH 4 production (DigOM/CH 4 ) at 24 and 72 h after commencement of inoculation, revealed that the amount of substrate required to produce 1 ml of CH 4 also differed significantly between cultivars ( P < 0·01). In Experiment 2, regrowth number significantly modified the majority of measured samples ( P < 0·01); cultivar effects were limited to the lag phase of the cumulative CH 4 production curve and DigOM/CH 4 at 8 h only ( P < 0·05). These results suggest that differences exist between cultivars in how OM is partitioned following microbial fermentation and that these differences demonstrate persistency throughout the growing season. In the course of time it may be possible to exploit these differences through cultivar selection and plant breeding programmes, and thereby reduce enteric CH 4 emissions within pastoral production systems.