The aim of the experiment was to investigate the ability of the heavy pig to utilize diets rich in fibre. Eight Landrace x
Large White fattening barrows were fed 3 high fibre (HF) diets (on average 17.8% NDF on DM) and a traditional (C) diet
(13.5% NDF) in a Latin Square design. Feeding was restricted. Each of the 4 periods included 21 days adaptation and 7
days digestibility/calorimetry. The HF diets included wheat bran (coarse or milled) or beet pulp. In periods 1, 2, 3 and 4
the eight pigs weighed, on average, 105, 124, 140 and 158 kg. Fibre digestibility (%) of HF diets increased from period
1 to period 4: 56.2, 56.6, 58.8, 62.2 for NDF and 46.0, 47.1, 49.0, 53.4 for ADF. A similar trend was registered for the
digestibility of DM, OM, CP, EE and energy. Comparing the digestibility of diet C with HF diets, independently of the periods,
diet C always had significantly higher digestibility (e.g. DM=87.5 vs 84.9%) except for fibre which gave similar coefficients.
Methane energy losses increased significantly from period 1 to period 4 for HF diets (0.40 vs 0.59% of the intake
energy, IE, P<0.05), while heat production and retained energy (% of IE), did not differ significantly between periods.
Retained energy of diet C (37.1% IE) and of HF diets (35.3%) considered as the average of the four periods, were similar,
confirming that the heavy pig can utilize fibre to a good extent. Considering the N balance of treatment HF, passing
from period 1 to period 4 concomitantly with a lower faecal excretion a significantly greater urinary excretion was recorded:
35.7 and 51.9% of intake N in periods 1 and 4, respectively (P<0.05). Total N excretion was similar in the four periods
(on average 0.98 g/BW0.75). However, expressing the data as % of the intake N, total N excretion increased from period
1 (54.6%) to period 4 (68.2%) (P<0.05). As a consequence, protein deposition (N*6.25) decreased from 155 to 126
g/d from period 1 to period 4 (P<0.05). On the contrary, fat deposition increased, as expected, in the four periods: 315,
359, 374 and 394 g/d