الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Contamination of feeds and feed ingredients may occur at any time before and after harvest and drying, during storage, processing and manufacturing. Chemically, Aflatoxins, a group of extremely toxic chemicals, are secondary metabolites produced by fungal species of the genus Aspergillus and the major types of aflatoxins are aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2). Among the aflatoxins, AFB1 was identified to be the most toxic and most prevalent compound, followed by G1, B2 and G2 with decreasing toxicity. Severe economic losses in poultry and livestock industries caused by the aflatoxin toxicity were reported. Aflatoxin intake in broilers is associated with liver damage, poor performance, immunosuppression and mortality. Aflatoxin toxicity in poultry is also associated with biochemical, hematological, reproductive and pathological changes and increased susceptibility to environmental and microbial stresses. Adverse clinical signs depend on the nature and concentration of mycotoxin, duration of exposure, animal species, age and the nutritional and health status of birds at the time of exposure to the contaminated feeds.
The present study was carried out at the Poultry Nutrition Farm, Poultry Production Department, Faculty of Agriculture, Ain Shams University during the period from 8 April 2011 till 20 May 2011. This current study was conducted in the two separate experiments. In the first experiment used the diets consisting of corn, soybean meal (Basal diets) and contain very low levels of Aflatoxins (less than recommended rates). In the second experiment used the diets consisting of corn, soybean meal (Basal diets) and contain high levels of Aflatoxins (higher than recommended rates). It was then added clay minerals, yeast and rice hulls to broiler diets in order to study the effect of getting rid of the negative effects of Aflatoxins on
productive performance, physiological parameters, histophathological changes and aflatoxin clearance for broiler chicks and economic evaluation.
Four hundred unsexed one-day old of Hubbard broiler chicks were obtained from commercial hatchery (Cairo poultry company), randomly distributed over 10 treatments within two experiments, Each treatment comprised of 40 chicks which divided into 4 replicates of 10 chicks each. Three periodical diets were formulated in two experiments includes, starter from 1 to 14 days of age, grower from 15 to 28 days of age and finisher from 29 to 42 days of age. Diets were formulated to contain 3000, 3100 and 3200 ME Kcal/Kg diets with 23, 21 and 19% crude protein for starter, grower and finisher diets respectively. The composition and calculated analysis of the diets formulated for starter, grower and finisher periods were done according to the based requirements of Hubbard broiler chicks at the strain recommended catalog. Chicks were vaccinated against Newcastle disease at 7, 21 and 28 days of age. Experimental diets and water were offered ad-libitum throughout the experimental periods. Body weight and feed consumption for all groups were recorded at the end of each period. Blood samples were collected from the slaughtered birds at the end (42 days of age) was determined.
Experiment 1:-
A total number of 200 unsexed one-day old Hubbard broiler chicks were used in this study. Chicks were divided randomly into five equal treatments (40 birds each). The first group of chicks was received the basal diets which containing 0.95, 1.13 and 1.32 μg of total aflatoxins /kg in starter, grower and finisher. Chicks of treatments 2, 3, 4 and 5 were received the control diet supplemented with 2.5% Rice hulls (RH), 5% RH, 0.2% hydrated sodium calcium
aluminosilicate (HSCAC) and 0.05% yeast cell wall (YCW), respectively. Main results obtained can be summarized as follows:
1- Rice hulls contained (dry matter 92%, crude protein 3%, crude fat 7%, crude fiber 39.40% and ash 18.90%); (Al 351.2, Si 900.7, P 4431, Ca 1086, Cu 6.451, Fe 723.5, Mn 84.52, Zn 14.49, k 6619 and Na 143) mg/ kg.
2- Broilers group fed 5% RH diet had the lowest average body weight and body weight gain at different periods of age. In addition, no significant differences were observed in LBW and BWG of birds fed control diet and those fed 2.5% RH, 0.2% HSCAS and 0.05% YCW diets.
3- There were no significant differences in feed consumption among birds fed different experimental diets during starter, grower and overall phases. Conversely, during the finisher phase (4-6 weeks of age), birds fed 5% RH diet consumed significantly (p<0.05) less feed than those fed control diet.
4- Feed conversion ratio (FCR) was significantly (P≤0.01) impaired with chicks fed 5% RH diet as compared to those un-supplemented control diet, 2.5% RH, HSCAS or YCW diet during the experimental period. In addition, no significant differences were observed between birds fed control, 2.5% RH, HSCAS and YCW diets.
5- The results in this study showed no significant differences among broiler groups fed different dietary treatments in relative weight of edible parts, carcass, heart and bursa. Birds fed 5% RH diet gave the highest values for giblets, gizzard and liver than those fed control diet and other treated groups.
6- Bird groups which fed diets containing 5% RH, 2.5% RH, HSCAS or YCW had significantly (P>0.01) increased aflatoxin B1 (AFB1) and total aflatoxins excretion in their excreta as compared to those fed control diet.
7- No significant differences were observed in total plasma protein and AST enzyme among experimental groups. The groups fed 5% RH or HSCAS diet had significantly lower values of total cholesterol and packed cell volume (hematocrit) than contaminated control and other treated groups.
8- Bird groups fed 2.5% RH, YCW and HSCAS gave the higher values in economic efficiency and relative economic efficiency than chicks fed 5% RH diet.
9- It could be concluded that, the possibility to using RH at 2.5 % HSCAS at 0.2 % or YCW at 0.05 % in starter, grower and finisher diets with total aflatoxin (0.95, 1.13 and 1.32 μg/kg) without any adverse effects on chick performance or carcass characteristics.
Experiment II:-
A total of 200 unsexed one-day old Hubbard broiler chicks were used in a completely randomized design to investigate the effects of Rice hulls (RH, at level of 2.5 or 5%), 0.2% HSCAC and 0.05% YCW, respectively, in aflatoxins contaminated diets (80.09, 96.10 and 112.12 μg /kg of feed in starter, grower and finisher period) on the performance, biochemical traits and the internal organ weights of broilers.
The main results can be summarized as the follow:
1. The lowest final live body weight and body weight gain were recorded for chicks received naturally contaminated diet with aflatoxins during the experimental period. Body gain values were significantly increased with supplementation of 2.5% RH, 5% RH, HSCAS and YCW into naturally contaminated diet with aflatoxins during the all experimental periods.
2. Broiler chicks group fed on naturally contaminated diet with aflatoxins had significantly (P≤0.01) reduced feed
consumption and impaired feed conversion ratio as compared with supplementation of 2.5% RH, 5% RH, HSCAS and YCW into naturally contaminated diet with aflatoxins during the all experimental periods.
3. Mortality rate of contaminated control group was higher (25.0%) followed by YCW, HSCAS and 5.0% RH groups (10.0, 7.5 and 5.0%, respectively) but, there is no moralities due to 2.5% RH group.
4. Edible parts, carcass, heart and bursa weights percentage were insignificantly differed in broiler groups received contaminated diet plus adsorbents than in contaminated control birds.
5. Relative weights of liver, gizzard and giblets for birds group fed on a naturally contaminated diet with aflatoxins plus YCW was significantly lower than those fed aflatoxins contaminated diet or other tested diets.
6. Birds fed on contaminated diet excreted low portion of aflatoxins in excreta, though kept high amount in their tissues.
7. Experimental broilers which fed on naturally contaminated diets contained 5.0, 2.5% RH followed by HSCAS group resulted in an increment of aflatoxins excretion in their excreta, thus an improvement in the broilers growth performance were obtained.
8. Broiler group received contaminated diet caused a significant (P0.01) increase in concentrations of ALT, AST, cholesterol and hematocrit than those of the contaminated diets supplemented with RH, HSCAS and YCW.
9. Levels of RH were found in the broiler diets significantly (P0.01) increased plasma total proteins as compared to the contaminated control diet group.
10. The lower values (P>0.01) of hematocrit was recorded for broilers group fed diet containing 5.0% RH, followed by those received diet supplemented with 0.2% HSCAS.
11. Economic efficiency and relative economic efficiency were decreased in the contaminated control group compared to the other treated groups. The highest economic efficiency and relative economic efficiency was obtained by birds given 2.5% RH followed birds by given 5.0% RH, while the other treatment groups were recorded the intermediate values for after mentioned.
12. Birds fed 2.5% RH diet recorded higher body weight gain, feed consumption, economic efficiency, relative economic efficiency, total plasma protein, lower total plasma cholesterol and better feed conversion ratio than those given contaminated control group and other treatment groups.
In conclusion, finally, the present results suggest that RH could be successfully used in broiler diets up to 5.0% RH and 0.2% HSCAS or 0.05% YCW could be supplemented to broiler diets without any harmful effects in the broiler performance, carcass characteristics and economic efficiency. These data indicate that the rice hulls effectively ameliorated the nnegative effect of aflatoxins on growth performance of broiler chicks.
Based upon these results, we suggest that addition of rice hulls to contaminated broilers diets with aflatoxins can be considered as a more effective for reducing the signs of aflatoxins toxicity, thus an improvement in the broilers growth performance were obtained.