Abstract. This study was carried out to investigate the effects of vitamins C and E on some plasma metabolites and production performance of layer chickens reared under hot tropical climate. 720 White Leghorn (L33) layer chickens and 39 weeks old were divided into four groups of 180 birds. One group was fed with basal diet (control) and treatment groups were fed with basal diet supplemented with 150 mg of vitamin C/kg of diet, 150 mg of vitamin E/kg of diet, while the last group was supplemented with 150 mg of vitamin C/kg of diet plus 150 mg of vitamin E/kg of diet. Separately or as a combination, supplemental vitamin C and E decreased plasma concentrations of cholesterol, glucose and creatine phosphokinase (P<0.001) compared to control. There were no significant (P>0.05) effects of supplemental vitamin C and E on plasma metabolites of alanine phosphatase and aspartate transaminase. The single supplementation of vitamin E and its combination with vitamin C considerably increased the plasma metabolite of protein (P<0.01). Egg/bird were significantly (P<0.05) higher in all treatment groups compared to control, but P value was highest in vitamin E treated group. The laying index showed a significant (P<0.05) increase in all treatment groups compared to control. Similarly, feed consumption and conversion were significantly (P<0.05) different in treatment groups compared to control. It is concluded that supplementation of vitamins C and E maintained the stability of some plasma metabolites concentration, thereby, sustained production performance and facilitated adaptation of chicken to stressful hot-humid condition.

The experiment was carried out in two stages with the objective of determining the effect of parenteral supplementation of 50 mg Cu on the reproductive behaviour of both hypo-and normocupremic cyclic female cattle. In the first stage, 62 hypocupremic, cyclic animals were selected, 32 heifers (16 in the control group and 16 in the treatment group) and 30 cows (12 in the control group and 18 in the treatment group). In the second stage, 98 normocupremic, cyclic heifers were selected (49 in the control group and 49 in the treatment group). 50 mg of Cu were administered to the animals in the treatment groups parenterally (subcutaneously) every two months until three successive applications were completed, while the control animals were not given copper supplementation. The effects of the copper therapy on cupremia and the percentage of heat and gestations presented were determined. The relative risk of treated animals of presentating anoestrus and service repetition was evaluated by the formation of a 2 × 2 contingency table and the application of a χ² test. The levels of serum copper were compared using a t-test, while heat and gestations were compared using a proportion comparism test. The parenteral administration of 50 mg Cu in hypocupremic, cyclic heifers and cows led to significant increases of cupremia (P<0.001) and the percentages of heat presentations and gestations (P<0.01); in the normocupremic animals, there were significant increases in the values of serum copper (P<0.0001), heat presentations (P<0.01) and gestations (P<0.001), especially in animals with cupremia values below 14 mmol/L. The treatment reduced the relative risk of reproductive disorders. It is concluded that the parenteral administration of 50 mg Cu in female cattle with Cu blood serum level <14 mmol/L increased cupremia and the percentages of heat presentations and gestations, and reduced the relative risk of reproductive disorders.

A 30-day experiment involving 720 White Leghorn (L33) layer chickens of 39 weeks of age and average live weight of 1.8 ± 0.04 kg was carried out in a completely randomized design to evaluate the effects of vitamins C and E on erythrocyte parameters of layers during natural summer conditions. Birds were allotted to 4 treatments containing 0, 150 mg vitamin C, 150 mg vitamin E, and 150 mg vitamin C plus 150 mg vitamin E/kg feed. Each treatment was replicated four times. The exposure of layers to 31±3 °C and 33±0 °C ambient temperature and 84.6% and 81.5% relative humidity, inside and outside the experimental pen, during the study period caused an increase in temperature humidity index 15.5 above the threshold value of 70 established for this species. Total erythrocytes counts were not affected by treatment. However, hematocrit and hemoglobin were significantly (p<0.001) different in vitamin-C and E treated groups, individually or in combination, as compared to the control birds. Also, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration of the birds fed vitamins C or E, or vitamins C+E were significantly (p<0.001) higher than those in control group. The results of the present study showed that the dietary supplementation of vitamin C and E, particularly as a combination, alleviated the counterproductive effects of high ambient temperature and humidity on the birds.

The objective of the present study was to determine the parenteral dosage of the trace mineral copper (Cu) which re-establishes serum and hepatic levels in hypocupperhemic animals without causing intoxication in the liver or residuals in milk. The experiment was carried out in two phases; in the first phase, 20 hypocupperhemic animals were used. Those were divided into 4 groups of 5 cows each: 3 groups which received 25, 50 and 100 mg of Cu respectively and 1 control group without supplementation, but with induced copraemia 5 days before and after the treatment. The milk of the cows treated with 100 mg Cu was examined for residuals of this element for one month. In the second phase, 25 animals were selected and divided into 5 groups of 5 cows each: 1 control group and 4 groups which received 25, 50, 100 and 200 mg of Cu respectively. The impact of this Cu dosages on liver reserves of this element, on hepatic enzymes (alanine-amine-transaminase, aspartate-amine-transferase, alkaline phosphatase and glutamate dehydrogenase) and on bilirubin was analyzed. The groups treated with 50 and 100 mg Cu showed increased levels in blood serum and hepatic tissues (P<0.05) in comparison to the control group and the one treated with 25 mg, obtaining the physiological level considered normal in cows during 60 days without an effect to the level of Cu in milk or to the liver's enzymatic activity. We conclude that treatment with this dosage results in a restoration of the Cu concentration in blood serum and hepatic tissues without toxic effects or residuals.