Effects of dietary supplementation with delta-aminolevulinic acid on growth performance, hematological status, and immune responses of weanling pigs

Delta-aminolevulinic acid (ALA) is a non-protein amino acid that plays a rate limiting role in the process of heme biosynthesis. In this study, the effects of supplementation of the diet with ALA on growth performance, hematological status, and immune responses in early-weanling pigs were evaluated. A total of 144 weaned castrated male pigs (6.37 ± 0.52 kg, 21 d of age) were blocked by BW and litter and allocated to pens, and, then, pens were assigned to 1 of 4 dietary treatments. There are 6 pigs per pen and 6 pens per treatment. The experiment were arranged as a 2 × 2 factorial arrangement of treatments with the inclusion of 2 levels of ALA (0 or 10 mg/kg) and antibiotics (0 or 40 mg/kg of apramycin). Blood samples were collected on d 0 and 42 to determine the hematological status and lymphocyte subpopulations via flow cytometry. Treatments with apramycin had greater ADG during d 7 to 21 (P < 0.05), whereas ALA had no effect on growth performance throughout the experiment. The serum hemoglobin (Hb) and hematocrit (HCT) values increased in response to ALA supplementation (P < 0.05). The total iron concentration and iron binding capacity (TIBC) were not affected by ALA or apramycin. The interaction between ALA and apramycin resulted in higher levels of cluster of differentiation antigens positive cells (CD) 8+ (CD8+), B cell, and majority histocompatibility complex cells I (MHC-I) (P < 0.01). The addition of ALA to the diet increased (P < 0.01) CD2+, CD8+, B-cell, MHC-I, and MHC-II compared with the group without ALA addition. Overall, the results of this study indicate that dietary supplementation with ALA had no effect on the growth performance of weanling pigs, but it improved iron status and affected the immune responses.