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Exogenous β-glucans are known for their ability to modulate the immune system. Two experiments were conducted to evaluate the effects of β-glucan inclusion in the diet on growth performance and immune function after lipopolysaccharide (LPS) challenge.
In Exp. 1, a total of 40 weaned pigs ((Landrace×Yorkshire)xDuroc) with an initial body weight (BW) of 7.89 ± 0.84 kg and 21 ± 2 d of age were used in a 28-day (d) experiment to determine the effects of dietary β-glucan on growth performance. Pigs were randomly allotted to two treatments consisting of addition of 0 or 0.1 g β-glucan/kg diet with four replicate pens per treatment and five pigs per pen. Growth performance was not affected by β-glucan supplementation. However, dietary β-glucan reduced (P<0.05) the counts of fecal Escherichia coli.
In Exp. 2, a total of 20 weaned barrows (6.22 ± 0.25 kg of BW and 21 ± 2 d of age) individually raised in metabolic cages to evaluate immunological responses following LPS challenge. Pigs were fed 0 or 0.1 g β-glucan/kg diet for 42 d. At the end of the trial, half of the pigs (n = 5) from each treatment were injected intraperitoneal with E. coli LPS at a concentration of 100 g/kg BW and the other half were injected with sterile saline solution. Treatments were arranged as a 2×2 factorial, with the main effect of LPS challenge (saline vs. LPS) and β-glucan supplementation (0 g/kg vs. 0.1 g/kg). After LPS injection, blood was taken at 0, 2, 4, 6, 8 and 12 hours (h) for the blood cell counts and blood inflammatory response. Dietary β-glucan increased (P<0.05) leukocytes counts at 4, 6 and 8 h, and blood lymphocyte concentrations at 2, 4 and 6 h and LPS challenge increased (P<0.05) counts of leukocytes at 2, 4, 6 and 8 h and blood lymphocyte at 2 and 4 h post-challenge. The rectal temperature was increased (P<0.05) at 2, 4, 6 and 8 h after LPS challenge. Dietary β-glucan reduced (P<0.05) and LPS challenge increased (P<0.05) blood plasma tumor necrosis factor (TNF-α) concentration at 2 and 4 h post-challenge. Dietary β-glucan increased (P<0.05) the concentration of the cluster of differentiation antigens 4 cells (CD4+) at 2, 4 and 6 h, and of 8 (CD8+) at 4 and 6 h post-challenge, respectively. The LPS challenge increased (P<0.05) CD4+ and CD8+ cell concentrations at 2, 4 and 6 h post-challenge. The CD4+:CD8+ ratio was reduced (P<0.05) by LPS challenge but was increased (P<0.05) by dietary β-glucan at 2, 4, 6 and 8 h post-challenge.
In conclusion, dietary β-glucan decreased E. coli numbers but did not affect growth performance in weaned pigs and may offer benefits on immune function in weaned pigs challenged with LPS.
Zhou, T.X., Jung, J.H., Zhang, Z.F., Kim. I.H. (2013) Effect of dietary β-glucan on growth performance, faecal microbial shedding and immunological responses after lipopolysaccharide challenge in weaned pigs. Animal Feed Science and Technology. 179: 85-92. http://dx.doi.org/10.1016/j.anifeedsci.2012.10.008