2.4. Experiment 2
Sixteen boars, with an initial BW of 18.9±2.2 kg were
used in Exp. 2. A study to determine the coefficients of total
tract apparent digestibility and P, Ca and N utilization was
carried out in conjunction with Exp 1 using pigs of same
genetic stock and previous history. The boars were blocked on
the basis of BW and litter of origin and were randomly
assigned to the four dietary treatments used in the weaner
performance study (Exp. 1). The pigs were allowed a 14-day
dietary adaptation period, weighed and transferred to
individual metabolism crates, which facilitated total but
separate collections of urine and faeces. The pigs were given
5 days to acclimate to the metabolism crates before 7 day
collections begun. The daily food allowance (MJ DE/d) was
calculated as 3.44×BW0.54 according to Close (1994) and was
divided over two meals. Water to feed ratio was 1:1. Fresh
water was provided on an ad libitum basis. The metabolism
crates were located in a temperature controlled room and
maintained at 25± 1.5 °C. During collections, urine was
collected in a plastic container via a funnel below the crate.
To avoid N volatilization, 20 ml (25%) of sulphuric acid
solution was added to the container daily. A solution (2%) of
sulphuric acid was applied to the connecting funnel twice
daily. The urine volume was recorded daily and the container
was then agitated to ensure homogeneity prior to the
collection of a 50 ml sample, which was frozen for laboratory
analysis. Total faeces weight was recorded daily and oven
dried at 100 °C. A sample of freshly voided faeces was
collected daily and then frozen (−20 °C) for N analysis. At
the end of the collection period, the faeces samples were
pooled and sub-sampled for laboratory analysis. Feed
samples were collected each day for chemical analysis.