<p>Odour emissions have been identified as a potential threat for the sustainable
development of the broiler industry. Few of the methods examined to reduce odour
emissions from poultry operations have proved effective. The methods including
biofilters, litter treatments, neutralising agents, air scrubbers, ozone treatment are
either impractical to apply or too costly to use in commercial farms. If diets could be
formulated to more closely meet nutrient requirements, there would be reduced
excretion of undigested components and lower level of substrates available for
microbes to metabolize them to odorous compounds. Diet affects water intake, water
to feed intake ratio, litter moisture, litter pH and litter water activity all of which may
have an impact on the emission of odorants from the litter. This thesis details the role
of diet composition, necrotic enteritis and litter condition on odour emission from
broiler production. This thesis includes a comprehensive review on key odorants
from broiler production, their origin, analytical techniques for odour measurements
and nutritional factors affecting odour emissions. The five chapters that follow
investigate the role of phytase enzyme (chapter 2), protein sources (chapter 3),
protein levels (chapter 4), probiotic and saponin (chapter 4), litter condition (chapter
4 and 5), necrotic enteritis and high sodium diet (chapter 5) and the effect of
<i>Clostridium perfringens</i> culture (chapter 6) on odour emissions. Nutritional strategies
such as increasing meat meal in the diet, decreasing dietary protein levels and the
addition of a <i>Bacillus subtilis</i> based probiotic and saponin blend may lower odour
emission from broiler production. The results also indicate that odour is related to
litter condition and if litter moisture content and water activity can be reduced and
necrotic enteritis prevented, odour problems can be alleviated in broiler sheds.</p>