Growth performance and intestinal microbial changes of <scp><i>Carassius auratus</i></scp> in response to pomegranate (<scp><i>Punica granatum</i></scp>) peel extract‐supplemented diets
Hamidreza Ahmadniaye Motlagh, Zahra Rokhnareh, Omid Safari, Yahya Selahvarzi
Abstract
Abstract This study aimed to investigate the effect of pomegranate ( Punica granatum ) peel extract (PPE) on growth indices, intestinal bacteria, and total fungi count of Carassius auratus intestine. Ninety C. auratus fries (11.04 ± 0.22 g) were distributed among 15 aquariums (100‐L) in a completely randomized design (triplicated), and were fed diets containing 0.1, 1, 2, and 4% PPE for 60 days at a feeding rate of 2% body weight during the experiment. A spectrophotometry assessment indicated that the total phenol and flavonoid content of PPE was 5.44 ± 0.03 and 49.80 ± 1.00 mg/g, respectively. According to the results, the extract significantly reduced the growth indices (final weight, weight gain, specific growth rate (SGR), and feed conversion ratio (FCR)) at 4% compared to the control ( p < .05). PPE did not affect the total aerobic bacteria or total lactic acid bacteria count, but the enteric gram‐negative bacteria count was significantly reduced in the experimental treatments ( p < .05). The total fungi count showed a significant increase in all treated fish ( p < .05). According to the results, because of the negative effect of the high dose of PPE on growth, there is a recommendation for it to be used at 2% of the diet to reduce intestinal gram‐negative bacteria and increase the total fungi count.