It has been projected that world food consumption will be doubled between 2010 and 2050 and the meat consumption per capita will also be rising due to the improvement in economic status in the developing areas of the world (Godfray et al., 2010). Modern-day broiler chickens are superior to other animals in producing meat from feedstuffs. The broiler industry is expected to expand in the coming decades, at the annual rate of 2.5% per year, to fulfil the increasing demand for a high quality and relatively inexpensive animal protein source, short generation intervals and very low greenhouse gas emissions (Cowieson and Selle, 2011). However, the broiler industry is facing many new challenges to meet society's expectation of having clean and green products without compromising food safety and quality, animal welfare and environmental care. ... The present study aimed to provide an insight into the efficacy of betaine in broiler production through its two roles, by examining its osmolytic capacity in enhancing the efficiency of energy utilisation, digestibility of other nutrients and activities of the gut microbial community, and by evaluating its methyl donor function, which partially replaces dietary methionine and improves carcass quality.