Abstract
This study was conducted to determine the effects of dietary supplementation of either 100 mg/kg chito- oligosaccharide (COS) or chlortetracycline (CTC) with corn-soybean-fish meal on immunity in broiler chickens. A total of 147 one-day old male broiler chicks were randomly allocated to 3 treatments with 7 replicate pens per treatment and 7 birds per pen. The experimental diets consisted of a control diet based on corn, soybean and fish meal without COS and any antibiotic supplement and similar diets supplemented with either CTC (80 mg/kg from d 1 to 21 and 50 mg/kg from d 22 to 42) or COS (100 mg/kg from d 1 to 42). During the entire experimental period, all birds had ad libitum access to diets and water. The main immune organ indices, T- lymphocyte proliferation, serum cytokine concentrations, serum NO level and serum iNOS activity were measured on d 21 and d 42. On d 21, broilers fed 100 mg/kg COS had improved (p<0.01) indices of spleen, thymus, and bursa of Fabricius compared with the control and CTC birds. Birds receiving 100 mg/kg COS had higher (p<0.05) serum concentrations of IL-1β, IL-6, IgM, NO and iNOS than birds on the control treatment. Serum Ca 2+ level of birds fed 100 mg/kg COS tended to be higher (p = 0.049) than in birds fed CTC. On d 42, the birds fed 100 mg/kg COS had higher (p<0.05) concentrations of TNF-α and IgM in serum than birds in both the CTC and control treatments. Birds fed 100 mg/kg COS had a higher concentration of IFN-γ than the control group. In conclusion, dietary supplementation of COS appeared to improve the immunity of broilers by promoting the weight of the main immune organs, increasing IgM secretion, stimulating microphages to release TNF-α, IL-1β, IL-6 and IFN-γ, and activating iNOS to induce NO. (Key Words : Chito- oligosaccharide (CTC), Immune Organ Indices, Cytokines, NO, Broiler)
Highlights
In modern broiler production, intensive genetic selection for fast growth rates and efficient feed conversion of broiler chickens is usually accompanied by greater mortality rates, mainly due to metabolic disorders, and eventually results in susceptibility to infectious diseases (Shapiro et al, 1998).Antibiotics, as growth promoters and therapeutic medicines to decrease susceptibility to infectious diseases, have been widely used in animal production for many years
The indices of spleen, thymus and bursa of Fabricius were significantly improved by supplementation with 100 mg/kg COS compared with the control and CTC treatments (p< 0.05)
Dietary supplementation of CTC in this experiment as negative control treatment would result in increased shedding of salmonellae and improve the severity of disease, as reported in Royal et al (1970)
Summary
Intensive genetic selection for fast growth rates and efficient feed conversion of broiler chickens is usually accompanied by greater mortality rates, mainly due to metabolic disorders, and eventually results in susceptibility to infectious diseases (Shapiro et al, 1998). Our previous studies have proved that dietary supplementation with COS could improve average daily gain of broilers and increase the apparent digestibility of broiler diets (Li et al, 2007). The objective of puncture into an anticoagulant vacuum tube to determine the present study was to investigate the effects of COS peripheral blood T-lymphocyte proliferation according to supplementation on immunity by determining the the method of Yuan et al (2005) with some modifications. The Control (Group 1) was fed the 5% CO2 for 66 h, and 10 ml of 3-(4, 5-dimethylthiazolcorn-soybean-fish basal diet without COS and any 2-yl)-2, 5 diphenyl tetrazolium On d 21 and d 42, one bird per pen (seven birds per the determination of the serum concentrations of calcium treatment group) was randomly selected, weighed and ion (Ca2+), NO, iNOS, tumor necrosis factor-α (TNF-α),
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