| Aflatoxins are toxins with great accumulative toxicity, which were classified as group I caicinogen by World Health Organisation. Aflatoxin B1 (AFB1) is the most widespread and toxic one of all the types of aflatoxins. Epidemiological investigation of duck feeds be contaminated by AFB1, pathogenicity of AFB1 on meat ducklings and the control measures were studied in this paper.1. Epidemiological investigation of duck feeds be contaminated by aflatoxin B1The purpose of this part was to investigate the pollution situation of aflatoxin B1 (AFB1) contaminated in duck feed materials during 2013 to 2015. ELISA method was used in the experiment to test the corn, soybean meal and peanut meal which was sampled from producing areas. (1) Test results of corn:According to the detection rate of toxin in corn to sort the areas during the period of 2013 to 2014:Central China region> East China region> Northwest region> North China region> Northeast region. Results of the detection rates were 100%, 52.4%,29.2%,19% and 15.4% respectively. Exceeding standard rates in Central China region was 85.7%, and 33.3% in East China region. All of the samples in the other areas do not exceed the standard of 20μg/kg. The pollution degree of AFB1 in corn was significantly lower during the period of 2014 to 2015. According to the detection rate of toxin in corn to sort the areas during the period of 2014 to 2015:Central China region> East China region> Northwest region> North China region> Northeast region. Results of the detection rates were 33.3%,24.4%,24.1%, 9.3% and 7.3% respectively. Exceeding standard rates in Central China region was 8.3%, and 4.4% in East China region. All of the samples in the other areas do not exceed the standard of 20μg/kg. (2) Test results of peanut meal:During the period of 2013 to 2014,90 samples which were collected from Henan and Shandong provinces were tested. Results of the detection rates were 100%. Exceeding standard rates in Henan province was 85.1%, and 93.8% in Shandong province. During the period of 2014 to 2015,131 samples were tested. Results were 96.9% and 100% respectively. Exceeding standard rates in Henan province was 77.3%, and 85.3% in Shandong province. (3) Test results of soybean meal:During 2013 to 2015,50 samples were tested. Result of the detection rate was 10%. All samples do not exceed the standard.During the period of 2013 to 2015, effects of feed which content of AFB1 exceeds the allowed figure on the performance in duck were analysed though visiting farm in Shandong, Anhui, Jiangsu and Hubei provinces combined with clinical symptoms, pathological changes and histological changes. The method of ELISA was used to test the contents of AFB1 in the feed in the farm. Twelve batches of feed which content of AFB1 exceeds the allowed figure were collected. Survey results showed, effects on meat duckling were most seriously, it could cause toxicity in meat duckling, and resulted in 10%-20% mortality. AFB1 intoxication death had not found in laying ducks, but toxin-contaminated feed lead to drop in laying production by 50%-80% and drop in egg weight by 20%-30%.2. Pathogenicity of AFB1 on meat ducklingsThe purpose of this study was to research the effects of AFB1 in feed on the growth, pathological changes of meat ducklings. And research the analgesic effect of mycotoxin adsorbent to the toxin-contaminated feed. A total of 160 healthy SM4 meat ducklings aged 1 day were randomly to 2 groups. The experiment was conducted for 28 days. The control group was fed by normal diet (AFB1 content was 8μg/kg). The dies of AFB1 group were formulated with naturally mycotoxin-contaminated corn, and AFB1 content was 60μg/kg. Performances were compared. At day 28, ducklings from each group were slaughtered for determining pathological section. Indexes reflect performance:Average daily gain (ADG), Average daily feed intake (ADFI), feed intake(FI), body weight(BW), feed to gain ratio(F/G), mortality rate.The results showed as follow:(1) Compared with the control group, the AFB1 group significantly decreased final weight (P<0.05). The results showed that the effects of toxin-contaminated feed on meat duckling were serious. (2) ADFI of the control group and AFB1 group were 114.48g and 107.05g respectively. Compared with the control group, the AFB1 group significantly decreased ADFI (P<0.05). The results showed that the effects of toxin-contaminated feed on ADFI on meat duckling were seriously. (3) F/G of the control group and AFB1 group were 1.70 and 1.82 respectively. Compared with the control group, the AFB1 group significantly increased F/G (P<0.05). The results showed that the effects of toxin-contaminated feed on F/G on meat duckling were serious. (4) Mortality rates of the control group, and AFB1 group were 1.25% and 11.25% respectively. Compared with the control group, the AFB1 group significantly increased the mortality rate (P<0.05). The results showed that the effects of toxin-contaminated feed on mortality rate on meat duckling were serious. (5) The pathological changes in liver of the AFB1 groups were serious. The form of hepatic lobules were indistinct, vacuolar degeneration and swollen in hepatocytes widely, fatty degeneration occured seriously, bile duct epithelium proliferated in the portal area. Kidney, renal tubules were dilated, and hyperaemia appeared. Multiple spotty necrosis and small inflammatory infiltrates could be found in the pancreas. The pathological structure of spleen was not affected in this experiment.3. Study on adsorption function of the mycotoxin adsorbentsThree experiments were conducted to determine the adsorption characteristics and effects of mycotoxin adsorbents on AFB1, vitamins and trace elements in Feed. Three adsorbents were selected as below:adsorbent A, main component is HSCAS; adsorbent B, main component is yeastcell extracts; adsorbent C, the compound of HSCAS and yeast cell extracts. Adsorption capacities of the three adsorbents were tested. A total of 240 healthy SM4 meat ducklings aged 1 day were used.The results showed as follow:(1) Adsorbent A was added into the AFB1 solution, contained 3 levels of adsorbent A (2mg/ml,3mg/ml,4mg/ml). With increase in adding levels, adsorbent A bound 57.14%,68.57%,74.29% of the AFB1 in solution respectively, and adsorbance per unit quality was 20μg/g,16μg/g,13μg/g respectively. Adsorbent B was added into the AFB1 solution, contained 3 levels of adsorbent A (0.5mg/ml, lmg/ml,2mg/ml). With increase in adding levels, adsorbent B bound 8.57%,10.00%,7.14% of the AFB1 in solution respectively, and adsorbance per unit quality was 12μg/g,7μg/g,2.5μg/g respectively. Adsorbent C was added into the AFB1 solution, contained 3 levels of adsorbent A (0.5mg/ml,1mg/ml,2mg/ml). With increase in adding levels, adsorbent C bound 42.86%,64.29%,78.57% of the AFB1 in solution respectively, and adsorbance per unit quality was 60μg/g,45μg/g,27μg/g respectively. (2) Adsorbent A, B, C were added into the vitamin B1 solution respectively, and the additive concentration of adsorbent was 50mg/ml. The stability of adsorbents in vitro condition were conducted. Adsorbent A and adsorbent C bounded 100% of the Vitamin B1 in solution respectively. Adsorbent B could not bound any of the Vitamin B1 in solution. Adsorbent A, B, C were added into the vitamin B6 solution respectively, and the additive concentration of adsorbent was 50mg/ml. The stability of adsorbents in vitro condition were conducted. Three adsorbents bounded 18.3%,5.08%,25.42% of the Vitamin B6 in solution respectively. Adsorbent A, B, C were added into the vitamin E solution respectively, and the additive concentration of adsorbent was 50mg/ml. The stability of adsorbents in vitro condition were conducted. Adsorbent C bounded 12.67% of the Vitamin E in solution. Adsorbent A and B could not bound any of the Vitamin E in solution. (3) Adsorbent A, B, C were added into the copper ion solution respectively, and the additive concentration of adsorbent was 50mg/ml. The stability of adsorbents in vitro condition were conducted. Three adsorbents bounded 37.45%,3.20%,42.01% of the copper ion in solution respectively. The same methods were used, three adsorbents had no absorption function to ferric ion, manganese ion and zinc ion. (4) Based on above experimental results, adsorbent A was selected to be tested on meat ducklings. The test was carried out with the methods used in the second part. The control group was fed by normal diet (AFB1 content was 3μg/kg). The dies of AFB1 group were formulated with naturally mycotoxin-contaminated corn, and AFB1 content was 52μg/kg. The dies of mycotoxin adsorbent group were same as the AFB1 group, but content 0.4% mycotoxin adsorbent. The results showed as follow:Compared with the AFB1 group, the mycotoxin adsorbent group significantly increased final weight (P<0.05). There was no significant difference in the control group and the mycotoxin adsorbent group(P>0.05). The results showed that mycotoxin adsorbent could alleviate the toxic effect significantly. ADFI of the control group, AFB1 group, and mycotoxin adsorbent group were 114.56g,108.73g and 115.75g respectively. Compared with the AFB1 group, the mycotoxin adsorbent group significantly increased ADFI (P<0.05), and the mycotoxin adsorbent group had no different to the control group. The results showed that mycotoxin adsorbent could increase ADFI significantly and up to the degree of the qualified feed. F/G of the control group, AFB1 group, and mycotoxin adsorbent group were 1.67,1.79 and 1.71 respectively. Compared with the control group, the AFB1 group and the mycotoxin adsorbent group both significantly increased F/G (P<0.05). Compared with the AFB1 group, the mycotoxin adsorbent group significantly decreased F/G (P<0.05). The results showed that mycotoxin adsorbent could decrease F/G significantly, but could not up to the degree of the qualified feed. Mortality rates of the control group, AFB1 group, and mycotoxin adsorbent group were 0,8.75% and 1.25% respectively. Compared with the AFBi group, the mycotoxin adsorbent group significantly decreased mortality rate (P<0.05). There was no significant difference in the control group and the mycotoxin adsorbent group(P> 0.05). Based on above experimental results, adsorbent A is an ideal adsorbent. |
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