Spirulina platensis as a growth booster for broiler; Insights into their nutritional, molecular, immunohistopathological, and microbiota modulating effects

Abstract

Background: The present study is designed to assess the effect of adding various doses of Spirulina platensis (SP) on broiler chicken growth performance, gut health, antioxidant biomarkers, cecal microbiota, histopathology, and immunohistochemistry of inducible nitric oxide synthase (iNOS). 240 male Cobb 500 broiler chicks (1 day old) were placed into four groups (sixty birds/group), then each group was further divided into three replicates of 20 chickens each for 35 days. Birds were allocated as follows; the 1st group (G1), the control group, fed on basal diet, the 2nd group (G2): basal diet plus SP (0.1%), the 3rd group (G3): basal diet plus SP (0.3%), and the 4th group (G4): basal diet plus SP (0.5%).

Results: Throughout the trial (d 1 to 35), SP fortification significantly increased body weight growth (BWG) and feed conversion rate (FCR) (P < 0.05). Bursa considerably increased among the immunological organs in the Spirulina-supplemented groups. Within SP-supplemented groups, there was a substantial increase in catalase activity, blood total antioxidant capacity, jejunal superoxide dismutase (SOD), and glutathione peroxidase (GPX) activity (P < 0.05). Fatty acid binding protein 2 (FABP2), one of the gut barrier health biomarkers, significantly increased in the SP-supplemented groups but the IL-1β gene did not significantly differ across the groups (P < 0.05). Different organs in the control group showed histopathological changes, while the SP-supplemented chicken showed fewer or no signs of these lesions. The control group had higher levels of iNOS expression in the gut than the SP-supplemented groups (p < 0.05). Cecal Lactobacillus count significantly elevated with increasing the rate of SP inclusion rate (p < 0.05).

Conclusion: Supplementing broiler diets with SP, particularly at 0.5%, can improve productivity and profitability by promoting weight increase, feed utilization, antioxidant status, immunity, and gastrointestinal health.

Keywords: And Antioxidant; Broiler; Growth performance; Gut health biomarker; Spirulina platensis.

Fig. 1

The effect of S. platensis on the antioxidant status of broiler chickens. A represents the serum TAC (mM/L), (B) plasma catalase activity (U/L), (C) jejunal SOD activity (U/gt), and (D) jejunal GPx activity (U/gt). G1: Control—basal diet; G2 basal diet plus 0.1% S. platensis; G3: basal diet plus 0.3% S. platensis; G4: basal diet plus 0.5% S. platensis). Data represented as mean value ± standard error (S.E.) where (n = 3/ replicate). Values with different superscripts are significantly different at P < 0.05

Fig. 2

The effect of S. platensis supplementation on the relative expression level of jejunal FABP2 and IL1β genes. qRT-PCR results are represented for (A) FABP2 gene, (B) IL-1β gene. G1: Control—basal diet; G2: basal diet plus 0.1% S. platensis; G3: basal diet plus 0.3% S. platensis; G4 basal diet plus 0.5% S. platensis). Data represented as mean value ± standard error (S.E.) where (n = 3/ replicate). Values with different superscripts are significantly different at P < 0.05

Fig. 3

Histopathology of chicken organs in different groups. a-d Liver, (a) G1(arrow), (b) G2, (c) G3, (d) G4;(X400). (e–h) intestine, (e) G1, (f) G2, (g) G3, (h) G4;(X100). (i-l) bursa (i) G1(arrow), (j) G2, (k) G3, (l) G4;(X400). (m-p) spleen, (m) G1 (arrow), (n) G2, (o) G3, (p) G4;(X 200). (q-t) thymus (q) G1(arrow), (r) G2, (s) G3, (t) G4; (X200). Hematoxylin and eosin stain. G1: Control—basal diet; G2: basal diet plus 0.1% S. platensis; G3: basal diet plus 0.3% S. platensis; G4: basal diet plus 0.5% S. platensis)

Fig. 4

Immunohistochemistry of iNOS in the chicken intestine. a G1(arrow), (b) G2, (c) G3, (d) G4. G1: Control—basal diet; G2: basal diet plus 0.1% S. platensis; G3: basal diet plus 0.3% S. platensis; G4: basal diet plus 0.5% S. platensis)

Fig. 5

The area % of iNOS expression in the intestine. G1: Control—basal diet; G2: basal diet plus 0.1% S. platensis; G3: basal diet plus 0.3% S. platensis; G4 basal diet plus 0.5% S. platensis). Data represented as mean value ± standard error (S.E.) where (n = 3/ replicate). Values with different superscripts are significantly different at P < 0.05