Development and Use of Rumen Molecular Techniques for Predicting and Enhancing Livestock Productivity

The world's livestock sector is amidst a massive transformation, fuelled by high demand for meat and milk, which is likely to double over the next two decades in developing countries. The major driving force behind this soaring demand for livestock products is a combination of population growth, urbanization and income growth, especially in developing countries. The challenge is to enhance animal productivity without any adverse effects on environment.
A large proportion of the global ruminant population is located in tropical environments, where animals feed predominantly on low quality highly fibrous forages. Recent studies in respiration chambers have confirmed that methane emissions from ruminants fed on fibrous diets are higher than outputs from better quality temperate forages. The excretion of methane from the rumen can represent a loss of up to 15% of the digestible energy depending on the type of diet. Therefore, reducing methane production could benefit the ruminant energetically provided the efficiency of ruminal metabolism is not compromised. The challenge therefore is to devise strategies, which reduce methane emissions from ruminants and improve production efficiency.
Current approaches to the evaluation of digestibility and nutritive value of feed resources using conventional in vitro feed evaluation and animal studies have resulted in a large body of information about nutrient composition, digestion kinetics and digestibility. However, these techniques are unable to describe the microbial mechanisms involved in ruminal digestion, and are unlikely to result in the development of rational feeding strategies.
Conventional culture-based methods of enumerating rumen bacteria are being rapidly replaced by the development of nucleic acid based techniques which can be used to characterise complex microbial communities. The foundation of these techniques is SSU rDNA (eg. 16S rRNA sequences) sequence analysis which has provided a phylogenetically based classification scheme for enumeration and identification of microbial community members. The molecular based ecology techniques are also likely to provide better insight into the interactions between methanogens and the other rumen microorganisms. All this information should assist in the development of strategies for improving production by reducing methanogenesis.
The Overall Objective of this CRP is to improve ruminant performance through a reduction in methane production. It is aimed to: i) reduce the level of methane production by up to 50% in animals fed roughage diets, ii) increase microbial protein and energy supply through reduced methane production using approaches such as inhibitors of methanogens, dietary approaches (e.g. use of polyunsaturated fatty acids or ingredients containing these acids), supplementation strategies, etc, iii) build in-country capacity to develop and use molecular techniques for studying rumen function, iv) develop molecular probes for quantifying populations of methanogens, fibre degrading bacteria, fungi and protozoa, v) correlate methane production to methanogen numbers, vi) determine effects of reduced methanogen numbers on fibre degrading bacteria, fungi and protozoa. Through these investigations, feeding strategies and or supplements that reduce methane production and improve productivity in ruminants on tropical diets will be developed, and better insight into the mechanism of feed digestion particularly interactions between various groups of rumen microorganisms will be available. This would lead to development of guidelines for reduction in methane emission and enhancement of animal productivity, for use at a wider scale.