Effect of Non-starch Polysaccharides on Mucin Secretion and Endogenous Amino Acid Losses in Pigs

P C H Morel,G Ravindran,R M Padilla

doi:10.5713/ajas.2003.1332

Abstract

This study was undertaken to examine the influence of soluble non-starch polysaccharides on growth performance, mucin secretion, and endogenous amino acid flows in weaner pigs. Different levels (0, 4 and 7.5%) of purified corn arabinoxylan (AX) or barley β-glucan extract (BG) were substituted for cellulose in a purified diet based on starch, sucrose and enzymatically hydrolyzed casein. All diets contained titanium oxide as an indigestible marker. Each experimental diet was fed to five, 6-wk old weaner pigs for 21 days. Average daily gain (p<0.05) and feed conversion ratio (p<0.01) were improved with dietary inclusion of 7.5% AX and BG, indicating high degradation rates of AX and BG in pigs. Crude mucin contents and endogenous nitrogen flow were increased (p<0.05) with increased levels of AX, but not with BG. Numerical increases in endogenous amino acid flow (EAAF) were observed with increased levels of AX but no definite trend with BG. Endogenous amino acid flow in pigs fed mixed NSP diets (4% BG and 3.5% cellulose) was significantly higher (p<0.05) than those fed 7.5% BG diets. Among diets containing pure sources of soluble non-starch polysaccharides, endogenous amino acid flows were highest in 7.5% AX (p<0.05), intermediate in BG, and lowest in control diet. Increased flows (p<0.01) of threonine, proline and serine in pigs fed 7.5% AX diets are consistent with the increased flow of crude mucin determined in this treatment. In conclusion, mucin and endogenous amino acid flows were increased with dietary inclusion of AX, which could be related to its physicochemical property, particularly its high water-holding capacity. In contrast, β-glucan, due to its high degradation rate in pig, may be considered as unimportant factor in inducing mucin and endogenous amino acid secretions, at least at levels such as those used in this study. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 9 : 1332-1338)

Highlights

Soluble and insoluble non-starch polysaccharides (NSP), found in viscous cereals such as wheat and barley, play an important role in monogastric nutrition because of their effects on endogenous protein secretion and nutrient digestion
Several studies have demonstrated that endogenous nitrogen losses in the distal ileum of pigs are influenced by various dietary factors, including the type and level of fiber (Sauer and Ozimik, 1986; Leterme et al, 1998; de Lange et al, 1989; Zebrowska and Kowalczyk, 2000) but how fiber components influences the increase in endogenous secretion remains unclear
Among the three pure Non-starch polysaccharide (NSP) sources, greater endogenous amino acid flows were observed in pigs fed with 7.5% AX, intermediate flow for 7.5% barley β-glucan extract (BG) and lowest for pigs fed with 7.5% cellulose

Summary

INTRODUCTION

Soluble and insoluble non-starch polysaccharides (NSP), found in viscous cereals such as wheat and barley, play an important role in monogastric nutrition because of their effects on endogenous protein secretion and nutrient digestion. A number of researchers (Fernandez and Jorgensen, 1986; Graham et al., 1986; Yin, 1994; Jorgensen et al, 1996) have shown that addition of dietary fiber to the diet results in reductions in the apparent ileal digestibility of starch, crude protein, fat and minerals These reductions can be associated with changes in the rate of absorption of nutrients or increased endogenous secretions. The effects of feeding different levels and types of soluble (arabinoxylan, β-glucan) and insoluble (cellulose) NSP on mucin secretion and, endogenous nitrogen and amino acid flows were investigated. AX=Arabinoxylan; BG=β-glucan. 1 Glutamic acid and aspartic acid values included glutamine and asparagines, repectively

MATERIALS AND METHODS

RESULTS

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DISCUSSION