CHROMIUM CHLORIDE AND ASCORBIC ACID RELIEVE THE CONSEQUENCES OF HIGH TEMPERATURE STRESS OF SUMMER IN BROILER

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 oC ±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 CrCl3.6H2O (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
CHROMIUM CHLORIDE AND ASCORBIC ACID252
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