This study was aimed at investigating (1) the effect of aflatoxin (AF) given in the feed, on fat, muscle and bone growth of broiler chicks, and (2) the possible reversal of aflatoxicosis by an anabolic agent, nandrolone decanoate (Trade name Deca-Duraboline). There groups, each of sixty four 1-day â€“old broiler chicks, were fed for 12 weeks a diet containing AF mixed at the rate of 2.5Âµg/g of feed and AF-free diet. Thirty two chicks from each group were injected with Deca-Duraboline at a dose of 0.1 MI/bird. Eight birds from each group were slaughtered at the age of 6 and 12 weeks.
Effect of Aflatoxin (AF)
1 AF. At a dose pf 5.0 Âµg /g of feed, significantly decreased, the live body weight (9% and 17%), dressed carcass weight (5% and 19%), carcass muscle weight (15% and 18%)and carcass bone weight (12% and 14%) after 6 and 12 weeks, respectively. The weight of carcass adipose tissue was, decreased with both AF doses.
2 The liver and kidney weights increased significantly after feeding AF mixed diet. A dose of 2.5 Âµg/g administered for 6 weeks did not affectliver weight. However, at 12 weeks of age an increase in the liver weight (18%) was obvious. Kidney weighty increased 9 and 10% at aflatoxin dose levels of 2.5 Âµg/ g and 5.0 Âµg/g respectively, only after 6 weeks. After 12 weeks, none of the doses of AF had any effect on kidney weight. A significant depression in the weight of immunogenic organs i.e. bursa of Fabricius and spleen was observed under all experimental conditions.
3 A significant decrease in the weights and lengths of most of the long bones was observed after AF feeding at a dose of 5.0 Âµg/g for 6 and 12 weeks. No significant effect of AF on circumference of all the long bones was observed.
4 The growth at the proximal tibial epiphysis, determined by oxytetracycline labelling, was significantly reduced after AF-mixed feeling at both doses.
5 Histological sections of the proximal tibial epiphyses were prepared, after incubating the epiphyseal ends in a medium containing 3H-thymidine, decalcification and autoradiography. Thickness of the proximal tibial growth plate, as measured in the histological sections, at the age of six weeks, was significantly reduced after AF treatment at the age of six weeks, was significantly reduced after AF treatment at the age of six weeks, was significantly reduced after AF treatment at both dose levels. Thickness of the proliferative zone within the growth plate and the number of cells/mm3 were not significantly affected at both dose levels. the percentage of tritium labelled cells in the proliferative zone were reduced in AF treated birds at both levels.
6 Proximal tibial growth plate cartilages were analysed for DNA and hydroxyproline contents and the rate of glycosaminoglycans synthesis. The DNA content was decreased in proximal tibial growth plate of broilers after treatment with AF at both the AF dosage regimes. The incorporation was also reduced at both the AF dosage regimes. The hydroxyproline content was not affected by any of the two doses.
7 Radial dimensions of muscle fibers of pectoralis and semitendinosis muscle were smaller in the birds given AF at both dose level for 6 and 12 weeks.
8 The total protein, RNA and DNA contents of both pectoralis and semitendinosis were significantly less in birds given AF at 5.0 Âµg/g level. Lower AF dose had no effect.
9 Cryosections of pectoralis and semitendinosis muscles were stained for AT Pase, phosphorylase and succinate dehydrogenase to classify them into type I, type IIA, types IIB and type IIC. Type IIC fiber type could not be seen in broilers. Both in pectoralis and semitendinosis type I fibers were proportionately decreased in number and type IIB were proportionately increased in the birds treated with AF at both dose levels.
Effect of Deca-Duraboline (DD) on AF â€“fed Chicks
1 Deca-Duraboline (DD) treatment in the chicks fed control diet significantly increased live weight (14% and 35%), dressed carcass weight (13% and 33%), and carcass muscle weight (7% and 34%) after 6 and 12 weeks, respectively. Significant increase in bone weight (9%) occurred only after 6 weeks. In chicks fed AF at 205 Âµg/g level, in most of the experimental conditions, a significant increase due to DD treatment occurred in live weight (11% and 14%), dressed carcass weight (5% and 17%),carcass muscle weight (8% and 17%) and carcass fat weight (35% and 11%) after 6 and 12 weeks, respectively. However, no significant effect of DD on the bone weight was seen in chicks fed AF at Âµg/g. DD treatment had no effect on live weight, dressed carcass weight, carcass muscle weight and carcass fat weight in chicks fed AF at 5.0 Âµg/g after 6 and 12weeds. Hence, DD was effective to a certain extent in alleviating the growth retarding effects of aflatoxicosis of the dose level of 2.5 Âµg/g
2 A significant increase (11.3%)due to DD treatment was seen in the liver weight, however, increased 16% in chicks injected with DD and fed on AF mixed diet at 5.0 Âµg/g. Thus DD had an additive role in increasing liver weight which was already increased due to aflatoxin. The kidney of chicks increased significantly in chicks fed AF contaminated diet at 2.5 Âµg/g (12%)and at 5.0 Âµg/g (12%) due to DD treatment. A significant increase of varying degree in the immunogenic organs i.e. bursa of Fabricius, thymus and spleen, occurred by DD treatment in all the experimental conditions at the age of 6 weeks. Increase of varying degree in the weight of lunges, pancreas and intestine was also seen due to DD treated chicks fed on control diet. In the chicks fed AF mixed diets, DD treatment had variable effects.
3 Weight, length and circumference of long bones (femur, tibia, humerus, radius and ulna) were not affected significantly by DD treatment in all of the experimental conditions, except in the case of femur which was increased in weight and length in DD treated chicks fed AFB1 at 5.0 Âµg/g.
4 Growth of tibial bone at the proximal epiphysis was significantly increased by DD treatment at 6 weeks in chicks fed AF mixed diet at 2.5 Âµg/g (10.5%) and 5.0 Âµg/g (11%).
5 Thickness of growth plate, thickness of proliferative zone, numbers of cells/mm3 in proliferative zone and hydroxyproline content of growth plate was not influence by DD treatment.
6 A significant increase in the number of 3H-thymidine labelled cells (8, 10 and 13%), DNA content (20, 8 and 1%) and 35SO4 incorporation (26, 28 and 35%)in the proximal tibial growth plate was evident in the chicks fed control diet and AF mixed diet at 2.5 Âµg/g and 5.0 Âµg/g level, respectively.
7 An increase in he radial dimensions of pectoralis and semitendinosis was observed in DD treated broilers, in all dietary regimes.
8 The RNA content increased (15% and 12%) in pectoralis muscle after DD treatment in broilers fed control diet for 6 and 12 weeks. These values were not affected, however, in chicks fed AF contaminated diet at 5.0 Âµg/g level. RNA content of pectoralis muscle was increased in DD treated chicks, consuming AFB1 at 2.5 Âµg/g (21% after 12 weeks) and 5.0 Âµg/g (22% after 6 weeks and 29% after 12weeds). A significant increase in the RNA content of semitendinosis muscle was also evident in chicks consuming AFB1 at both 2.5 Âµg/g (14% after 6 weeks and 18% after 12 weeks ) and 5.0 Âµg/g levels (18% after 6 weeks and 21% after 12 weeks).
9 No effect of DD administration was seen on various muscle types in pectoralis and semitendinosis under all experimental conditions.
It is concluded that AFB administration had growth suppressing effects on most of the tissues of broiler chicks, particularly at the dose level of the tissues of broiler chicks, particularly at the dose level of 5.0 Âµg/g DD treatment promoted tissue growth and was effective, to some extent, in ameliorating the growth suppressing effects of AFB1 at 2.5 Âµg/g dose level.