Digestion of diets containing molassed or plain sugar-beet pulp by growing pigs

Abstract

Large White × Landrace pigs were grown from 25 to 55 kg on diets containing 0, 150, 300 or 450 g kg −1 molassed (M) or plain (P) sugar-beet pulp (SBP) (coded C, 15 M, 30 M, 45 M, 15 P, 30 P, 45 P, respectively). The apparent digestibilities of dry matter (DM), nitrogen (N), non-starch polysaccharides (NSP) and neutral detergent fibre (NDF) of the diets were determined when pigs attained live weights of 27 and 50 kg. Diets contained similar amounts of DM, N and gross energy (GE). Levels of dietary NSP and NDF increased with SBP content. The major NSP residues in SBP were uronic acids, arabinose and glucose, in the approximate ratio of 1:1:1, whereas glucose accounted for 66% of the NDF NSP. In 27-kg pigs given Diet 45 P, digestibilities of DM and N were significantly reduced relative to the control. In contrast, digestibilities of the NDF and NSP fractions of most SBP diets were higher than those of Diet C. When pigs had attained 50 kg live weight, digestibilities of all components had increased, and there were no significant differences in the digestibility of DM between each of the seven diets. However, the abilities of 50-kg pigs to digest the N and NSP fractions of Diet C were higher and lower respectively, than those of similar pigs fed Diet 45 P. The arabinose and uronic-acid content of the diets were highly digestible as were the minor components mannose, galactose and non-cellulosic glucose. Xylose and glucose were poorly digested by 27-kg pigs, but their digestion by 50-kg pigs was substantially improved. Increasing inclusion levels of SBP resulted in concomitant increases in faecal bulk. These results indicate that young pigs fed diets containing up to 300 g kg −1 MSBP, can digest DM and N as well as, and NDF and NSP better than, pigs fed a conventional diet without SBP.