Methane formation in faunated and ciliate-free cattle and its relationship with rumen volatile fatty acid proportions

Abstract

1. Twelve steers fitted with rumen cannulas were used in three separate experiments to investigate the effects of the presence or absence of rumen ciliate protozoa on methane production. The diet consisted of 850 g barley and 150 g protein supplement/kg, and was given in three feeds daily at a restricted level of 61 g/kg live eight^''^. Animals were defaunated initially by allowing ad lib. consumption of this diet and were then maintained ciliate-free by isolation or were faunated by inoculation with a mixed ciliate suspension. Samples of rumen fluid were taken routinely for the assessment of microbial populations and for volatile fatty acid (VFA) analysis and energy and nitrogen balances and digestibility measurements were made at intervals while animals were confined in respiration chambers.2. In each experiment the rumen VFA proportions changed from a high-propionate pattern under ciliate-free conditions to a low-propionate, high-butyrate pattern in the presence of ciliates: differences between treatments were highly significant (P < 0.001). There were also marked differences between treatments in CH, production but a reliable comparison was possible only in Expt 3, in which CH, was significantly higher (P < 0.001) in the presence of a rumen ciliate population. In Expt 3 the increased loss of energy as CH, in the faunated animals amounted to 4 4 MJ/100 MJ energy intake.3. Stoichiometric estimates of CH, production derived from the observed VFA proportions showed good agreement with CH, production as measured in respiration chambers. On average, the stoichiometric CH, values overestimated CH, production by a factor of 1.08. 4.Highly significant linear relationships (P < 0.001) were observed between the molar proportion of each major VFA and the quantity of CH, produced: the proportion of propionic acid was inversely related to CH, and showed the lowest residual standard deviation of all the relationships examined.5. The losses of energy in faeces and urine did not differ between treatments hence the increased loss of energy as CH, in the faunated animals resulted in a significant reduction in the metabolizability of the diet from 0.73 to 0.69 (P < 0.05). No significant differences were detected between treatments in heat production, apparent digestibility coefficients or N balance.6. It is suggested that the rumen ciliates, by modifying the rumen VFA proportions, are directly responsible for the increased CH, production in faunated animals.Previous work in this laboratory has shown that rumen ciliate protozoa are normally absent from cattle given ad lib. access to an all-concentrate diet but can be established in large numbers when the same diet is given in amounts below appetite (Eadie et al. 1970). When intake is restricted and the daily allowance is offered in three equal meals the presence of ciliates gives rise to marked changes in the pattern of rumen fermentation. In particular, rumen pH is higher and the volatile fatty acids (VFA) in rumen fluid show a lower proportion of propionic acid and a much high...

Effects of feed carbohydrates with contrasting properties on rumen fermentation and methane release in vitro

“…This was underlined by the fact that butyrate, a major product from sugar fermentation, was found to be positively correlated with methane production (r = 0.67; P < 0.001; n = 32). This relationship was also reported by Whitelaw et al (1984) and Pinares-Patiño et al (2003).…”

Mitigation strategies to reduce enteric methane emissions from dairy cows: Update review

“…However, with the rising public and health authorities concerns about the use of chemical or antibiotic feed additives in animal production, the use of ionophores to mitigate CH 4 production might not be the best conceivable option. Defaunation Defaunation, which is the elimination of protozoa from the rumen by dietary or chemical agents, has been shown to reduce ruminal CH 4 production by about 20 to 50% depending on the diet composition (Whitelaw et al 1984;Itabashi et al 1994;Van Nevel and Demeyer 1996). Whitelaw et al (1984) observed that faunated cattle fed barley diets at restricted levels lost about 12% of GEI as CH 4 compared to 6-8% of GEI in ciliate-free animals.…”

“…Defaunation Defaunation, which is the elimination of protozoa from the rumen by dietary or chemical agents, has been shown to reduce ruminal CH 4 production by about 20 to 50% depending on the diet composition (Whitelaw et al 1984;Itabashi et al 1994;Van Nevel and Demeyer 1996). Whitelaw et al (1984) observed that faunated cattle fed barley diets at restricted levels lost about 12% of GEI as CH 4 compared to 6-8% of GEI in ciliate-free animals. Protozoa in the rumen are associated with a high proportion of H 2 production, and are closely associated with methanogens by providing a habitat for up to 20% of rumen methanogens (Stumm et al 1982;Newbold et al 1995a).…”

Influence of substrate and microbial interaction on efficiency of rumen microbial growth

“…Higher feeding levels and/or grinding concentrate diets lowers protozoal count through acidification and increased tonicity associated with intensive fermentation, reduced salivation and lower k, values, although other factors may be involved (Lyle et al, 1981). Many animals on highconcentrate feeds are defaunated (Johnson, 1976) and high concentrate feeding is in fact an efficient defaunation procedure (Whitelaw et al, 1984a (Coleman, 1979).…”