Non-specific immune parameters and physiological response of Nile tilapia fed β-glucan and vitamin C for different periods and submitted to stress and bacterial challenge.
This study attempts to describe the effects of different administration periods of dietary β-glucan and Vit C on the non-specific immune response, physiological parameters and disease resistance of Nile tilapia against Aeromonas hydrophila infection. Therefore, a feeding trial (288 fish) was conducted to determine the best administration period (7, 15, 30 and 45 days) for a Nile tilapia diet supplemented with 0.1% β-glucan and 600 mg Vit C/kg diet. After the administration period, three different groups of 96 fish were exposed to one of the following three stresses: cold-induced stress, transport-induced stress, and A. hydrophila challenge. Hematological, biochemical and immunological responses were analyzed before and/or after stress. Cold-induced stress increased cortisol levels and reduced the leukocyte count in fish fed the test diet for seven days compared with the other periods. After transport-induced stress, fish fed the test diet for seven days required more hours to return to the baseline levels of cortisol and neutrophils. Moreover, independently of the administration period, fish needed 24 h for leukocyte and glucose levels to return to the initial values. The lowest survival after bacterial infection was observed in fish test diet for seven days. Based on fish hematological and biochemical responses, diet supplemented with 0.1% of β-glucan and 600 mg of Vit C/kg fed for at least 15 days is recommended for Nile tilapia especially when fish are likely to encounter transport-induced stress, and this stress was more severe than cold-induced stress or bacterial challenge.
UNESP, Univ. Estadual Paulista, FMVZ, AquaNutri, Botucatu, SP, Brazil. Electronic address: mbarros@fmvz.unesp.br.
Margarida Maria
MM
Barros
UFRP, Univ. Federal Rural Pernanbuco, Serra Talhada, PE, Brazil.
Dario Rocha
DR
Falcon
UNESP, Univ. Estadual Paulista, FMVZ, AquaNutri, Botucatu, SP, Brazil.
Ricardo de Oliveira
Rde O
Orsi
UNESP, Univ. Estadual Paulista, FMVZ, AquaNutri, Botucatu, SP, Brazil.
Luiz Edivaldo
LE
Pezzato
UNESP, Univ. Estadual Paulista, FMVZ, AquaNutri, Botucatu, SP, Brazil.
Ademir Calvo
AC
Fernandes
UFG, Univ. Federal de Goiás, LAPAQ, Jataí, GO, Brazil.
Igo Gomes
IG
Guimarães
UNESP, Univ. Estadual Paulista, FMVZ, AquaNutri, Botucatu, SP, Brazil.
Ary
A
Fernandes
UNESP, Univ. Estadual Paulista, FMVZ, AquaNutri, Botucatu, SP, Brazil.
Carlos Roberto
CR
Padovani
UNESP, Univ. Estadual Paulista, FMVZ, AquaNutri, Botucatu, SP, Brazil.
Maria Márcia Pereira
MM
Sartori
D016980:Aeromonas hydrophila; D000704:Analysis of Variance; D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D017756:Aquaculture / Q000379:methods; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D001938:Brazil; D023681:Cichlids; D003080:Cold Temperature; D019587:Dietary Supplements; D060467:Disease Resistance / Q000187:drug effects / Q000276:immunology; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology*; D016905:Gram-Negative Bacterial Infections / Q000276:immunology / Q000662:veterinary*; D013312:Stress, Physiological / Q000187:drug effects; D047071:beta-Glucans / Q000008:administration & dosage / Q000494:pharmacology*
D047071:beta-Glucans; D001205:Ascorbic Acid
Aeromonas hydrophila; Immunostimulant; Stress; Vit C; β-glucan