Twenty-four finishing boars (78 kg; SD ± 2.3 kg; n = 6) were blocked based on sex, and assigned to 1 of the 4 experimental treatments. After a 14-d dietary adaptation period, the pigs were transferred to individual metabolism crates. The pigs were allocated 5-d to adapt to the metabolism crates before collections commenced. The collection period was subdivided into
three parts to facilitate studies on manure ammonia emissions (d 1–2), manure odour emissions (d 3–5) and faecal collections
(d 6–10). The daily feed ration [digestible energy (DE) intake (MJ/d) = 3.44 × (BW)0.54 ; Close, 1994] was offered over 2 meals.
Fresh water was provided with meals in a 1:1 ratio. Between meals water was provided ad libitum. The metabolism crates were located in a temperature controlled room maintained at a constant temperature of 22 ◦C (±1.5 ◦C). Upon cessation of
the collections from the metabolism crates, the pigs were slaughtered and digesta samples were taken from the ileum in order to measure apparent ileal N and GE digestibility using the acid insoluble ash technique (McCarthy et al., 1977). Celite was added to all diets at a rate of 1 kg/tonne.