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Effects of algae derived β-glucans on nursery pig growth performance and immune response under commercial conditions
A total of 2,484 pigs (PIC 337×1050, initially 7.1±0.12 kg) were used to determine the impact of increasing levels of a commercial β-glucan (Algamune ZPC, Algal Scientific Corporation, Plymouth, MI) on growth performance and Porcine Circovirus Type 2 (PCV2) specific immune response of nursery pigs housed under commercial conditions. Pigs were allotted to 1 of 6 treatments in a randomized complete block design with BW as a blocking factor with 27 pigs/pen and 14 or 16 pens/treatment. Dietary treatments, fed in two phases from d 0 to 12 and d 12 to 40 postweaning, were a negative control diet or the negative control diet with 125, 250, 500, or 750 ppm added β-glucan in both Phases; or the negative control diet with 500 ppm added β-glucan during Phase 1 and the negative control diet in Phase 2. Phase 1 diets contained 1,910 ppm of zinc oxide. All pigs were vaccinated with PCV2 and M. hyopneumoniae vaccines with 2 mL per pig (1 mL Fostera™ PCV and 1 mL Respisure-One®; Zoetis, Florham Park, NJ) at d 3 after birth and at weaning. Blood samples (12 pens/treatment) were collected at d 2, 18 and 38 of the trial from 12 pigs/treatment. For the immune response analysis, weight block within serum sampling period and pen within dietary treatment were included in the model as random effects. Pigs fed increasing β-glucan marginally decreased then increased (quadratic, P=0.09) ADG (457, 448, 450, 453, and 461±15.5 g/d) and tended to increase (linear, P=0.10) ADFI (692, 675, 685, 688, and 704±27.2 g/d). No evidences for differences were observed in G:F (P=0.36). There was no evidence of a difference (P>0.54) in ADG, ADFI or G:F when comparing pigs fed 500 ppm β-glucan in both phases compared with pigs fed 500 ppm β-glucan only in Phase 1. There was a tendency (linear, P=0.07) for decreased PCV2 neutralizing antibody titers as the inclusion of β-glucan increased. There was no evidence of differences (P=0.75) in PCV2 neutralizing antibody titers between pigs fed 500 ppm in both phases and pigs fed 500 ppm only in Phase 1. In conclusion, dietary addition of up to 750 ppm of β-glucan in nursery pig diets from 7 to 25 kg had minimal impact on growth performance. Also, modulation of the specific immune response to PCV2 at d 38 after weaning was negatively related to increasing β-glucan under commercial conditions.
Keywords: β-glucans, immune response, nursery