The potential of Spirulina platensis to substitute antibiotics in Japanese quail diets: impacts on growth, carcass traits, antioxidant status, blood biochemical parameters, and cecal microorganisms

Abstract

The development of antibiotic-resistant microorganisms prompted the investigation of possible antibiotic substitutes. As a result, the purpose of the current study is to assess the effect of dietary Spirulina platensis extract as an antibiotic alternative on Japanese quail (Coturnix japonica) growth, antioxidant status, blood parameters, and cecal microorganisms. There was a total of 150 Japanese quails used in this study, divided equally among 5 experimental groups (10 birds per group with 3 replicates): group 1 (G1) received a basal diet without any S. platensis extract, group 2 (G2) received a basal diet supplemented with 1 mL S. platensis extract/kg, group 3 (G3) received a basal diet supplemented with 2 mL S. platensis extract/kg, group 4 (G4) received a basal diet supplemented with 3 mL S. platensis extract/kg, and group 5 (G5) received a basal diet supplemented with 4 mL S. platensis extract/kg from d 7 until d 35. The results showed that compared to the control birds in G1, Japanese quail supplemented with 4 mL of S. platensis extract/kg of diet (G5) had significantly better live body weight, body weight gain, feed intake, feed conversion ratio, digestive enzymes, blood parameters, liver and kidney functions, lipid profile, antioxidant profile, immunological parameters, and cecal microorganism's count. There were no significant changes in the percentage of carcasses, liver, and total giblets among all the 5 groups. Only gizzard percentage showed a significant increase in G2 compared to birds in G1. In addition, intestinal pH showed a significant drop in G2 and G5 compared to birds in G1. After cooking the quail meat, the juiciness and tenderness increased as S. platensis extract levels increased, whereas aroma and taste declined slightly as S. platensis extract levels increased. Furthermore, when a high concentration of S. platensis extract was used, the lightness of the meat reduced while its redness and yellowness increased. The disk diffusion assay showed that S. platensis extract had significant antibacterial activity against Staphylococcus aureus, Listeria monocytogenes, Campylobacter jejuni, and Salmonella typhi, with inhibition zones ranging from 16 to 42 mm. This activity may be attributable to the volatile chemicals in S. platensis extract, of which Geosmin and 2-methylisoborneol are the primary components. In the diet of Japanese quails, it is possible to draw the conclusion that the extract of S. platensis can be utilized as a feed additive and as an alternative to antibiotics.

Keywords: Japanese quail; Spirulina platensis; antibiotic alternative; cecal microorganisms; liver and kidney functions.

Figure 1

Photomicrograph of sections of quail intestine (upper panel) and liver (lower panel) stained with hematoxylin and eosin at 100×. (A upper panel), in the intestine of control quail (birds not supplied with S. platensis extract), showing the denuded villi tips (arrow) due to desquamations enterocytes into their lumina (star) with limitation of their goblet cells (100×), (B upper panel) G2 (birds fed with 1 mL S. platensis extract/kg diet) showing a few desquamated parts in lumen (arrow) with mild goblet cells metaplasia (100×), (C upper panel) G3 (birds fed with 2 mL S. platensis extract/kg diet) showing more healthy arranged tall separated villi (arrow) with increase intestinal crypts activation (star) (100×), (D upper panel) G4 (birds fed with 3 mL S. platensis extract/kg diet) showing more healthy arranged tall separated villi (arrow) with increase intestinal crypts activation (star) (100×), (E upper panel) (birds fed with 4 mL S. platensis extract/kg diet) showing marked thin villi (star) with still presence of mild goblet cells metaplasia (arrow) (100×). (A lower panel), in the liver of control quail (birds not supplied with S. platensis extract/kg diet), liver cell showing normal cell architecture (arrow) without any structural abnormality (star), (B lower panel) G2 (birds fed with 1 mL S. platensis extract/kg diet) liver cell showing normal cell architecture (arrow) without any structural abnormality (star), (C lower panel) G3 (birds fed with 2 mL S. platensis extract/kg diet) showing showed normal hepatocytes and sinusoids of control quails, no eosinophilia, centrilobular necrosis, vacuolation or inflammatory cell infiltration (arrow) (100×), (D lower panel) G4 (birds fed with 3 mL S. platensis extract/kg diet) showing showed normal hepatocytes and sinusoids of control quails, no eosinophilia, centrilobular necrosis, vacuolation or inflammatory cell infiltration (arrow) (100×), (E lower panel) (birds fed with 4 mL S. platensis extract/kg diet) showing showed normal hepatocytes and sinusoids of control quails, no eosinophilia, centrilobular necrosis, vacuolation or inflammatory cell infiltration (arrow) (100×).

Figure 2

Antibacterial activity of Spirulina platensis extract (SPE) against pathogenic bacteria. SA, Staphylococcus aureus; LM, Listeria monocytogenes; CJ, Campylobacter jejuni; and ST, Salmonella typhi. Values with same letter are not significantly (P>0.05) different according to protected least significant difference (LSD) test. IZD, inhibition zone diameter in mm; MIC, minimum inhibitory concentration.