The effect of organic and inorganic zinc source, used with lignocellulose or potato fiber, on microbiota composition, fermentation, and activity of enzymes involved in dietary fiber breakdown in the large intestine of pigs

The study aimed at determining the effects of Zn sources, used with potato fiber (PF) or lignocellulose (LC), on microbiota ecology in the large intestine of pigs. The hypothesis was that organic Zn source, i.e. Zn glycinate (ZnGly), and PF improve polysaccharide digestibility via effects on microbiota involved in degradation of dietary fiber. Twenty four piglets of initial body weight 10.8 +/- 0.82 kg were divided into 4 groups (n=6) fed diets with: LC and ZnSO4, LC and ZnGly, PF and ZnSO4, and PF and ZnGly. Fiber supplements introduced 10 g crude fiber/kg diet, while Zn additives provided 120 mg Zn/kg diet. After 4 weeks of feeding digesta was taken from 4 segments of the large intestine. Pigs fed ZnGly diets had greater population of Clostridium herbivorans in the cecum (P = 0.021) and proximal colon (P = 0.024), and reduced that of Clostridium spp. in the proximal colon (P = 0.037) in comparison with ZnSO4. ZnGly had no effect on bacterial enzymes activity but increased total phenols concentration in the proximal (P = 0.012) and distal colon (P = 0.008). Feeding PF diets decreased Clostridium spp. population in the distal colon (P = 0.010), while increased it in the proximal (P < 0.001) colon (P = 0.034) as compared to LC diets. In all parts of the colon, pigs fed PF diets had beta-glucosidase activity twice as high as animals on LC diets (P < 0.05), while activity of cellulase did not differ between treatments. The interaction affected Clostridium spp. population in the cecum (P = 0.034) and middle colon (P = 0.005), ammonia concentration (P = 0.032) and beta-glucosidase activity (P = 0.026) in the proximal colon, and isoacid concentrations in the distal colon (P < 0.05). The lack of interactive effect on most of the analyzed indices suggest that Zn source and fiber supplementation act independently on microbiota ecology and ZnGly and PF contribute to increase of fiber digestibility in different ways, i.e. by stimulation of C. herbivorans growth or by increase of beta-glucosidase activity.