Date of Award
4-2024
Document Type
Doctoral Thesis
Degree Name
Doctor of Philosophy
Department
Biological and Pharmaceutical Sciences
First Advisor
Dr. Shane O' Connell
Second Advisor
Patrick Quille
Third Advisor
Dr. Tim Yeomans
Abstract
Ruminant dietary additives were investigated for enteric methane (CH4) mitigation and their effects on rumen fermentation characteristics during both in vitro and in vivo supplementation trials. A meta-analysis of the peer reviewed published literature was initially performed to establish the state of the art in the field and allowed benchmarking of the performance of the dietary additives screened during the project. Investigated feed additives included garlic oil (GO), nitrate, Ascophyllum nodosum (AN), Asparagopsis (ASP), Lactobacillus plantarum (LAB), calcareous marine algae (CMA), chitosan (CHI), essential oils (EO) and 3-nitrooxypropanol (3-NOP). The development of an in vitro screening method to evaluate the potential of feed additives utilising freshly collected rumen fluid revealed anti-methanogenic properties in several rumen additives while monitoring rumen fermentation parameters such as total gas production and volatile fatty acid (VFA) profiles. The screening of the feed additives revealed considerable CH4 mitigating potential for CMA rumen buffers (27.6 %), GO (38.1 %) and the combination of the CMA rumen buffer with the essential oil (41.7 %) at their lowest optimum dosages. A correlation between in vitro and in vivo methods for evaluation of rumen CH4 mitigation was also established. Calcareous marine algae fortified with magnesium oxide (CMA.MgO) showed good potential for improved average daily gain (ADG), reduced CH4 production (in agreement with in-vitro work), and maintenance of rumen fermentation metabolite production when supplemented in Angus heifers fed a 50 % w/w: 50 % w/w forage to concentrate (high starch) diet ratio. Additional mode of action investigations demonstrated the relationship between CMA rumen buffering capacity and promotion of favourable VFA profiles that sequester available hydrogen (H2) from methanogenesis pathways resulting in reduced CH4 production.
Recommended Citation
Hodge, Ian, "Investigating Essential Oils, Natural Compounds, and Marine Based Rumen Buffers as Feed Additives for Enteric Methane Mitigation and Improved Ruminant Productivity" (2024). Theses [online].
Available at: https://sword.mtu.ie/allthe/858
Access Level
info:eu-repo/semantics/openAccess