Nutraceuticals vs. antibiotic growth promoters: differential impacts on performance, meat quality, blood lipids, cecal microbiota, and organ histomorphology of broiler chicken

Abstract

The main goal of this study was to evaluate the effect of nutraceuticals vs. in-feed antibiotics on performance, blood lipids, antioxidant capacity, cecal microbiota, and organ histomorphology of broiler chickens. A total of 320 one-day-old male broiler chickens were distributed into 5 treatment groups with 8 replicates each. The control group was fed on a basal diet without any additives (NC); the antibiotic group was fed on a basal diet supplemented with 100 mg kg-1 avilamycin (PC); the algal group was fed on a basal diet supplemented with a mixture of Spirulina platensis and Chlorella vulgaris (1.5 g + 1.5 g/kg feed) (SP+CV); the essential oil group was fed with a basal diet containing 300 mg/kg feed rosemary oil (REO); and the probiotics group (a mixture of 1 × 10¹¹ CFU/g Bacillus licheniformis, 1 × 10¹¹ CFU/g Enterococcus facieum, 1 × 10¹⁰ CFU/g Lactobacillus acidophilus, and 2 × 10⁸ CFU /g Saccharomyces cerevisiae) was fed with a basal diet supplemented with 0.05% probiotics (PRO). The experiment lasted for 35 d. A beneficial effect of SP+CV and PRO (P < 0.01) was noticed on final body weight, body weight gain, feed conversion ratio, and breast yield. The dietary supplementation with SP+CV, REO, and PRO increased (P < 0.001) broilers' cecal lactic acid bacteria count compared to the control. Lower cecal Clostridium perfringens and Coliform counts (P < 0.001) were noticed in chickens fed the PC and supplemental diets. Malondialdehyde (MDA) concentration was decreased, while glutathione peroxidase (GPx), superoxide dismutase, and catalase enzymes were increased in the breast and thigh meat (P < 0.001) of broiler chickens fed SP+CV, REO, and PRO diets. Dietary SP+CV, REO, and PRO supplementation decreased (P < 0.001) serum total lipids, cholesterol, triglycerides, low-density lipoprotein, and MDA, but increased serum high-density lipoprotein and GPx compared to PC and NC. No pathological lesions were noticed in the liver, kidney, or breast muscle among broilers. The SP+CV, REO, and PRO groups had greater (P < 0.001) intestinal villi height and crypt depth while lower goblet cell densities (P < 0.01) than the control. The present findings suggest that PRO and SP+CV, followed by REO could be suitable alternatives to in-feed antibiotics for enhancing the performance, health, and meat quality of broiler chickens.

Keywords: antibiotic alternative; broiler chicken; meat quality; nutraceutical; performance.

Figure 1

Histological examination of the small intestine (duodenum, jejunum, and ileum) of broiler chickens showed normal features without any pathological lesions. TM, tunica mucosa; V, intestinal villi; TS, tunica submucosa; G, goblet cells; M, tunica muscularis; S, tunica serosa. Small intestine stained by Hematoxylin and Eosin (×40 & ×100). NC, negative control, basal diets; PC, positive control, basal diet supplemented with antibiotics; SP+CV, basal diets supplemented with a combination of Spirulina platensis and Chlorella vulgaris; REO, basal diets supplemented with rosemary essential oil; PRO, basal diets supplemented with probiotics.

Figure 2

Scanning electron microscope of the small intestine (duodenum, jejunum, and ileum) of broiler chickens showed normal features. TM, tunica mucosa; V, intestinal villi; TS, tunica submucosa; M, tunica muscularis; S, tunica serosa. NC, negative control, basal diets; PC, positive control, basal diet supplemented with antibiotics; SP+CV, basal diets supplemented with a combination of Spirulina platensis and Chlorella vulgaris; REO, basal diets supplemented with rosemary essential oil; PRO, basal diets supplemented with probiotics.

Figure 3

Histological structure of the liver of the treatment groups. The livers of broiler chickens showed normal features, normal arrangement of hepatic plates and hepatocytes (H), normal central vein (CV), portal area (PA), and normal sinusoids (S). A fine network of reticular fibers appeared in black color (red arrow) and collagen fiber was stained in green color (black arrow). NC, negative control, basal diets; PC, positive control, basal diet supplemented with antibiotics; SP+CV, basal diets supplemented with a combination of Spirulina platensis and Chlorella vulgaris; REO, basal diets supplemented with rosemary essential oil; PRO, basal diets supplemented with probiotics.

Figure 4

Histological structure of kidney of the treatment groups. Kidneys showed normal structure. RC, renal cortex; RM, renal medulla; CG, cortical glomeruli; MG, medullary glomeruli; CT, renal collecting tubules; proximal convoluted tubules (red arrow); and distal convoluted tubules (black arrow). (H&E stain). NC, negative control, basal diets; PC, positive control, basal diet supplemented with antibiotics; SP+CV, basal diets supplemented with a combination of Spirulina platensis and Chlorella vulgaris; REO, basal diets supplemented with rosemary essential oil; PRO, basal diets supplemented with probiotics.

Figure 5

Cross section of breast muscle of the experimental broilers. Breast muscles show normal architecture without any pathological lesions. The muscle fibers (MF) appear rounded or polygonal in shape with their nuclei peripherally situated. Thin connective tissue septa surround and support the muscle bundles or fascicles, called perimysium (black arrow). A thin delicate reticular network surrounds the individual muscle cell containing blood capillaries, nerve (blue arrow), and fibroblasts called endomysium (red arrow). NC, negative control, basal diets; PC, positive control, basal diet supplemented with antibiotics; SP+CV, basal diets supplemented with a combination of Spirulina platensis and Chlorella vulgaris; REO, basal diets supplemented with rosemary essential oil; PRO, basal diets supplemented with probiotics.