1. Introduction
The contribution of intensive pig production to manure malodour and ammonia emissions is caused in part through
oversupply of dietary protein (Hayes et al., 2004). Excessive protein consumption causes both urinary nitrogen (N) excretion
as urea, and the conveying of undigested proteinaceous material to the distal gastrointestinal tract (dGIT) (Carpenter et al.,
2004; Lynch et al., 2007a). The bacterial degradation of such nitrogenous compounds generates ammonia and pungent
volatile fatty acids which contribute to subsequent manure emissions