| A cottonseed meal naturally contaminated with aflatoxins is used as the source of aflatoxins in this study. The objective of the study is to investigate the effects of aflatoxins on growth performance, immune indices, liver function and hepatic pathological observation for Cherry Valley Ducks, and evaluate the efficacy of different kinds of binders in eliminating aflatoxin-induced adverse effects. A total of 360 one-day-old Cherry Valley male ducks were randomly divided into 4 dietary treatments with 6 replications per treatment. The four diets formulated included a basal diet(T1), a contaminated diet(T2) and two contaminated diets supplemented with 2 g/kg binders of montmorillonite or yeast cell wall(T3, T4). Of those, the contaminated diet was formulated by replacing common cottonseed meal with 8% naturally moldy one(aflatoxins, 1337.21 ug/kg) on the equal nutrient level basis. Ducks had access to feed and water ad libitum throughout the whole study period, starter(1-14d) and finisher(15-35d). Indexes reflect performance: Live weight(LW), average daily gain(ADG), average daily feed intake(ADFI), feed/gain(F/G), slaughter performance; Indexes reflect immune function: relative weight of spleen, thymus and bursa of fabricius, concentration of immunoglobulin A(Ig A), immunoglobulin G(Ig G) and immunoglobulin M(Ig M); Indexes reflect liver function: concentration of total protein(TP), albumin(ALB), activity of alkaline phosphatase(ALP), alanine transaminase(ALT), aspartate transaminase(AST), relative weight of liver, the pathological changes in the liver tissue sections were measured on d 7, 14, 21, 28, 35.(1) The equations between live weight, breast muscle weight and thigh muscle weight and age were better fitted with Gompertz functional equation(R2≥0.97). The weight of growth inflexion was decreased and the ages of it were delayed with the ducks feeding the contaminated feed. The correlation between breast muscle and live weight was better fitted with polynomial regression and power regression(R2=0.99). The correlation between thigh muscle and live weight was better fitted with linearity regression, polynomial regression and power regression(R2=0.99). All the results of F-test were significant(P<0.01).(2) Moldy cottonseed meal(MCM) significantly decreased LW, ADG and ADFI of every stage(P<0.05), and significantly increased F/G of every week(except d 7-14)(P<0.05). Mycotoxin binders(MB) significantly increased LW of every stage(P<0.05), significantly increased ADG and ADFI of every week(except d 22-28)(P<0.05), decreased F/G of d 15-21, 29-35, 15-35(P<0.05). T3 group had significant improved the LW of d 14, the ADG of d 8-14 and 1-14, the ADFI of d 8-14, 22-28, 1-14, 15-35, and lowered the F/G of d 22-28 and 15-35 than T4 group(P<0.05).(3) MCM significantly increased relative weight of spleen in whole experiment period(except d 28)(P<0.05), increased relative weight of thymus and bursa of fabricius of every stage(P<0.05), increased serum Ig A of d 14, 21, 28(P<0.05), decreased Ig G and Ig M of the whole experiment(P<0.05). MB significantly decreased relative weight of spleen of d 7, 21, 35 and the relative weight of thymus and bursa of fabricius of every stage(P<0.05), decreased serum Ig A of d 14, 28 and Ig G and Ig M of every stage(P<0.05). Ducks in T4 group had higher relative weight of spleen at d 14, 21, 35, relative weight of thymus at d 7, 28, 35, relative weight of bursa of fabricius in every stage, Ig A at d 28 and lowered Ig G and Ig M in whole experiment than that in T3 group(P<0.05).(4)MCM decreased TP, ALB of all stages and the ALP activities of d 14, 21, 28(P<0.05), increased the ALT activities and relative weight of liver of every stage and the AST activities of d 7, 14, 28(P<0.05), induced significantly pathological changes in the liver tissue sections. MB increased TP of d 7, 14, 21, 35, ALB of d 14, 21, 35 and the ALP activities of d 14, 28(P<0.05), decreased the ALT activities and the relative weight of liver of every stage and the AST activities of d 7, 14, 28(P<0.05). Ducks in T4 group had lower serum TP at d 7, 14, 28, ALB at d 14, 35, ALP activities at d 14 and 28 than that in T3 group(P<0.05). T4 group had significant improved the relative weight of liver of d 14, 21 and 28, the ALT activities of the whole stage, and the AST activities at d 7,14,28(P<0.05).These results indicated that feeding diet with the natural moldy cottonseed meal could decrease the growth performance, the immune function was heavily damaged, tissue lesion happened in liver, and the function of liver was changed with varied enzyme activities changes. The adsorbents were effective in increasing performance, alleviating the damage to immune function caused by aflatoxins and the hepatotoxicity of aflatoxins. And addition of montmorillonite could more effectively ameliorate the negative effect of the moldy cottonseed meal than the yeast cell wall. |
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