In vitro fermentation patterns and methane production as influenced by cultivar and season of harvest of Lolium perenne L.

Abstract

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 (l) of CH 4 production at both time of 0AE5A(T 1 2 )(lCH 4 T 1 2 ) and at 48 h (lCH 4 48h) were significantly (P < 0AE05) 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 < 0AE01). In Experiment 2, regrowth number significantly modified the majority of measured samples (P < 0AE01); cultivar effects were limited to the lag phase of the cumulative CH 4 production curve and DigOM/ CH 4 at 8 h only (P < 0AE05). 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.

Nutritional Value ofAcacia AmentaceaandParkinsonia TexanaGrown in Semiarid Conditions

“…It is often claimed that forage-based diets generally result in higher enteric CH4 (Klevenhusen et al, 2011); nevertheless, a negative correlation albeit no significant (r=-0.932; P=0.068) was found between the tannin content and CH 4 production (Guglielmelli et al, 2011), indicating that CH4 production consistently declined as the structural compounds content increased. Nevertheless, in this study GEL values were not related to the NDF (r=0.040; P>0.01), whereas the relationship with the NSC (data not shown) was negative (r=-0.477; P<0.01) as also found by Lovett et al (2006).…”

“…Significant differences in chemical composition among seasons in native browse plants have been reported by others (Lovett et al, 2006). Environmental changes alter the nutritional quality of plants; in this way, high temperatures and the development of its water transport system (xylem) increased the NDF content (Hoffman et al, 2007).…”

Effect of feeding dried high-sugar ryegrass (‘AberMagic’) on methane and urinary nitrogen emissions of primiparous cows

“…Lovett et al (2004) found no effects on CH 4 production in vitro, but this may be attributed to the unexpected low differences in the WSC concentration of test cultivars of only 11 g/kg DM. However, later Lovett et al (2006) showed a potential of lowering in vitro CH 4 formation when the difference in the WSC concentration of ryegrass was 33 g/kg DM whereas again no effect was found when the difference was low (14 g/kg DM). Comparing three ryegrass cultivars with WSC concentrations of around 300 g WSC/kg DM to a ryegrass cultivar ('Premium') with 270 g WSC/kg DM, only one of the high-WSC cultivars decreased in vitro CH 4 emissions (Niderkorn et al, 2009).…”

“…When related to milk yield, CH 4 might still be low due to the expected high concentration of net energy for lactation (NEL) of high-WSC grasses, which promotes feed conversion efficiency and might increase milk yield. However, in two in vitro experiments (Lovett et al, 2006;Niderkorn et al, 2009), CH 4 formation per unit of feed was found to be lower with high-WSC compared to low-WSC ryegrass cultivars. A preliminary report (abstract by Kim et al, 2011) indicated that this also might be true in vivo.…”

Strategies for Reducing Methane Emissions from Ruminants (Estratégias para a Redução da Emissão de Metano por Ruminantes)

“…One option that should be explored is the development through breeding of tropical grass cultivars containing high levels of water soluble carbohydrates to increase animal performance as a consequence reduce CH 4 per unit of product as has been shown with ryegrass genotypes in the UK (Lovett et al, 2006 genetic improvement of forage grasses and legumes to reduce greenhouse gas emissions.…”