Adaptation to the digestion of non-starch polysaccharide in growing pigs fed on cereal or semi-purified basal diets

Pigs (25-45 kg) were fed on either cereal or semi-purified basal diets supplemented with either high or low levels of sugar-beet pulp or wood cellulose (Solka-floc). The apparent digestibility and retention of N and apparent digestibility and metabolizability of energy (GE) and the apparent digestibility of non-starch polysaccharides (NSP) and their constituent monomers were measured during weeks 2, 4 and 6 of the trial. N and GE were less well-digested, retained or metabolized from cereal basal diets than from the corresponding semi-purified diets during all three periods. NSP from sugar-beet pulp was highly digestible, unlike that from Solka-floc which was relatively poorly digested. These differences of NSP digestibility were seen more clearly when incorporated in semi-purified diets. There was no significant increase in the digestibility or retention of N, or digestibility or metabolizability of GE, or in the digestibility of sugar-beet pulp NSP with increasing time-period on the diets. In contrast, the digestibility of Solka-floc NSP tended to increase with the time-period. The digestibility of NSP from the semi-purified diet with the high level of Solka-floc inclusion was much lower than that for the low level of inclusion, indicating that microbial activity had been reduced. In conclusion, adaptation to the diets in terms of N and GE balance may be complete after 1 week, but 3-5 weeks may be necessary before stability of measurements of the digestibility of resistant NSP monomers can be obtained.