Dietary nucleotides supplementation improves the intestinal development and immune function of low birth weight piglets

Abstract Text: This study aimed to determine whether dietary nucleotides supplementation could improve growth performance, intestinal development and immune function of low birth weight (LBW) piglets. Piglets with a birth weight near the mean litter birth weight (SD 0.5) were identified as normal birth weight (NBW), whereas those with at least 1.5 SD lower birth weight were defined as LBW. Fourteen pairs of NBW and LBW piglets (7 day old) were randomly assigned to receive a liquid milk-based control diet (CON diet) or diet supplemented with nucleotides (NT diet) for a period of 21 day. NT diet was formulated by adding 0.74% nucleotides in CON diet, the pattern of nucleotides (5’-AMP, CMP, GMP, IMP, UMP) was similar as that in sow milk. Data were analyzed by SPSS software using the MIXED procedure. Compared with NBW piglets, LBW piglets had significantly lower average daily dry matter intake (P = 0.001) and average daily gain (P < 0.001). Moreover, LBW decreased the villous height (P = 0.008) and villi: crypt ratio (P = 0.014) in duodenum, as well as maltase (P = 0.033) activity in jejunum. In addition, LBW decreased the serum concentrations of immunoglobulin A (P < 0.001), interleukin-1β (P = 0.017) and interleukin-10 (P = 0.008), as well as the percentage of peripheral lymphocytes (P = 0.015). Meanwhile, the down-regulation of innate immunity-related genes such as Toll-interacting protein (TOLLIP) (P = 0.012) and Toll-like receptor (TLR) 2 (P = 0.073) was observed in the ileum of LBW relative to NBW piglets. Regardless of birth weight, however, feeding NT diet decreased (P = 0.001) the feed: gain ratio, increased villous height in duodenum (P = 0.036), activities of lactase (P = 0.019) and maltase (P = 0.055) in jejunum, also increased count of peripheral leukocytes (P = 0.039), serum concentrations of immunoglobulin A (P = 0.001) and interleukin-1β (P = 0.019) as well as gene expressions of TLR-9, TLR-4 and TOLLIP (all P < 0.05) in ileum. In addition, the protein expressions of Claudin-1 and Zonula occludens-1 (P < 0.05) in ileum were markedly increased by feeding NT diet relative to CON diet. Our results indicated that LBW impaired the growth performance, intestinal and immune function, but dietary supplementation of nucleotides improved the growth performance, digestive capability and immunity.

Keywords: low birth weight, nucleotides, immunity