Chromium chloride and ascorbic acid relieve the consequences of high temperature stress of summer in broiler

الملخص EN

Seventy-two Hy-line white hens with 32 weeks old were maintained in layer batteries with three decks to the fortieth week of age from July to September where the maximum ambient temperatures was 34 °C ± 2.

Birds were individually weighed and distributed randomly into four experimental groups of 18 hens with six replicates (cages) of three hens each.

The laying hens of each group were fed the basal diet alone as control (group 1) or the basal diet supplemented with 80 mg CrCl3.6H20 (group 2), or with 250 mg vitamin C (group 3) and with the combination of Cr and Vit C (group 4).

The basal diet was formulated to contain 18 % crude protein and 2800 Kcal ME / kg of diet.

The obtained results showed significant increasing in plasma concentration of T3 hormone by the supplementation with Cr especially when it added together with vitamin C.

All supplementations ; Cr, vitamin C and their combination increased significantly the plasma concentration of T4 hormone.

The same effect could be observed by the supplementation with Cr and became higher when added together with vitamin C on increasing significantly the plasma concentration of insulin.

The MDA (malondialdhyde) levels in plasma were decreased significantly especially by the application of Cr together with vitamin C, followed by Cr application individually and then by vitamin C alone.

Supplementations with Cr, vitamin C separately and in combination have pronounced effects on the plasma concentrations of glucose, total lipids and cholesterol, but their effect on total protein and albumin was not significant.

Plasma calcium (Ca) and inorganic phosphorous (Pi) were significantly changed by dietary supplements of Cr and vitamin C, since, Ca significantly increased in all treatments, however, Pi had inconsistent trend.

The activities of ALP, AST and ALT enzymes showed pronounced changes under the effect of the addition of Cr and vitamin C either separately or in combination together.

ALP activity decreased significantly by the adding of Cr alone and also in combination with vitamin C.

AST activity decreased significantly by vitamin C supplementation, while the ALT enzyme activity increased significantly by the supplementation with vitamin C and became higher when supplemented together with Cr.

As results of the pronounced changes in plasma hormones, metabolites, minerals and enzymes activities under the effect of the supplementation with Cr and vitamin C, the productive performance of the laying hens were affected diversely.

No significant effect on body and egg weights of laying hens along the experimental period could be detected under all treatments.

Feed intakes significantly increased by adding Cr and/or vitamin C.

Significant improvement in feed conversion ratio could be obtained by Cr, vitamin C and Cr + vitamin C supplementation along the whole experimental period The supplementations with Cr or vitamin C separately or in combination together were significantly increased egg number and egg mass of laying hens along the experimental period in addition to an enhancement in egg shell thickness (mm) of treated hens.

The result indicates that the combination between Cr and vitamin C as dietary supplementation could achieve good results better than their individual supplementation.