Experimental design and measurements
The study was conducted as a randomised complete block design with 60 pens divided over three nursery rooms filled 2 weeks apart. Each room had four blocks representing areas within room with five pens. Pens of pigs within block were randomly allocated to be fed one of five dietary regimens during the 35-day study for a total of 12 replicate pens per treatment. Pens (1.1 m × 1.5 m) were equipped with a 4-space dry feeder (model N4-424; Crystal Spring, MB, Canada), a nipple drinker, polyvinyl chloride partitions and plastic flooring. Rooms were ventilated using negative pressure, maintained within the thermo-neutral zone for the pigs and provided a 12-h light (06:00–18:00 h), 12-h dark cycle. Pigs had continuous access to feed and water.
To calculate average daily feed intake (ADFI), average daily weight gain (ADG) and feed efficiency (G:F), individual pigs, pen feed added and feed remaining were weighed weekly. To calculate CATTD of DM, GE and CP, freshly-voided faeces were collected immediately upon defaecation from 08:00 to 16:00 h by grab sampling from pen floors on d 12 and 13 for Phase 1 and d 33 and 34 for Phase 2. To avoid contamination of collected faeces, pens were washed prior to the collection to remove old faeces and feed spills. Faeces were pooled by pen and stored frozen at −20 °C for storage. Afterwards, faeces were thawed, homogenised, sub-sampled and freeze-dried.