الفهرس 
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Abstract
The present study was carried out at Feeds and Fattening Unit in Animal Production Farm, located in Abbis region, belonging to the Animal and Fish Production Department, Faculty of Agriculture (El- Shatby), Alexandria University, during the period from April to August 2008, to investigate the effect of organic selenium as selenium yeast (SeY) and/or vitamin E (Vit. E) supplementation to the diet of buffalo calves on their growth performance, body measurements, nutrients utilization, blood biochemical and hematological parameters. Twenty four weaned male buffalo calves, average body weight (BW) 74.7 ±1.5 kg, were used in this study. Calves were distributed into 4 experimental groups (6 calves for each) and randomly assigned to the following treatments:
1. Control group was fed a basal diet which consisted of concentrate and berseem hay without any supplementations. Two types of concentrates (starter concentrate mixture for the first 8 weeks and commercial concentrate for another 8 weeks) were used.
2. Selenium yeast group was fed control diet supplemented with 0.3 mg SeY /head/day.
3. Vitamin E group was fed control diet supplemented with 250 mg Vit. E/head/day.
4. Selenium yeast and vitamin E group was fed control diet supplemented with 0.3 mg SeY plus 250 mg Vit. E/head/day, respectively.
These supplementations were incorporated daily with the concentrate.
The results obtained could be summarized as follow:-
1. Final BW of buffalo calves numerically increased by dietary supplementation of SeY and/or Vit. E as compared to the control group.
2. Average daily gain (ADG) of buffalo calves didn’t significantly affect by different supplementations, while calves supplemented with Vit. E recorded the best ADG as compared to the other groups.
3. Average feed conversion ratio (FCR, kg dry matter/kg gain) insignificantly improved as a result of different supplementations. However, the best improvement of FCR was noticed with buffalo calves supplemented with Vit. E followed by calves supplemented with SeY plus Vit. E.
4. All body measurements of buffalo calves insignificantly affect by different supplementations at 8 and 16 weeks from the beginning of the experiment. However, calves supplemented with SeY plus Vit. E recorded the highest value of height at wither (HW) at 8 weeks from the beginning of the experiment. Meanwhile, at 16 weeks from the beginning of the experiment, the highest values of HW, width at pin bones (WP) and body depth (BD) were observed with supplementation of Vit. E alone, while inclusion of SeY showed the highest values of chest girth (CG) and diagonal body length (DBL).
5. Changes in CG, body length (BL) and DBL of buffalo calves significantly influenced as a result of different supplementations at 8th week of the experiment, the highest value of CG change was recorded with SeY plus Vit. E group, while the highest value of BL change was observed with Vit. E group and the highest value of DBL change was recorded with control group. Meanwhile, at 16th week of the experiment, changes in CG, HW and BD differed significantly (P<0.05) with different supplementations. Selenium yeast plus Vit. E treatment showed the highest value of CG change, meanwhile Vit. E treatment showed the highest values of changes in HW and BD.
6. The results revealed that there were a positive correlation between different body measurements and BW of buffalo calves during allover the experimental periods. At 4 months of age (at 8 weeks of the experiment), correlation coefficients of CG, HW and WP were significant (P<0.01). The highest correlation coefficient (0.63) and prediction variable or regression coefficient (40%) were found with the WP, so the convenience linear regression equation is Y= -11.824 + 4.127(WP). Meanwhile, at 6 months of age (at the end of the experiment), all correlation coefficients of different body measurements with BW were significant except BD. Diagonal body length showed the highest correlation coefficient (0.62) and regression coefficient (38%), thus the suitable linear regression equation is Y= 52.23 + 1.06 (DBL).
7. All the experimental supplementations significantly increased the overall means of serum total protein and globulin as compared to the control group. Meanwhile, SeY plus Vit. E supplementation significantly increased overall mean of serum albumin as compared to the control group and insignificantly as compared to SeY or Vit. E supplementation. All the experimental supplementations decreased overall mean of serum albumin/globulin ratio as compared to the control group.
8. Vitamin E supplementation alone or plus SeY significantly decreased total mean of serum total cholesterol in comparison with the control group and insignificantly in comparison with SeY group. Regarding to serum triglycerides, all the experimental supplementations significantly decreased total mean of serum triglycerides in comparison with the control group.
9. Selenium yeast plus Vit. E supplementation resulted in a significant increase overall mean of serum high density lipoprotein (HDL) as compared to other groups, also, SeY or Vit. E treatments increased (P<0.05) serum HDL as compared to the control group. Meanwhile, overall mean of serum low density lipoprotein significantly decreased with different supplementations as compared to the control group.
10. Adding the combination of SeY and Vit. E to the diet of buffalo calves had a positive effect on liver and kidney functions as indicated from the reduction (P<0.05) of overall means of serum aspartate transaminase enzyme activity and creatinine level, respectively.
11. All dietary supplementations significantly increased total mean of serum glutathione peroxidase activity as compared with the control group.
12. Selenium yeast plus Vit. E supplementation considerably increased total mean of white blood cells count in comparison with other supplementations and the control group. Meanwhile, red blood cells count (RBCs) didn’t affect by different supplementations, while, the highest value of RBCs count was observed by dietary supplementation of SeY plus Vit. E. Dietary supplementation with Vit. E alone or in a combination with SeY significantly increased total mean of hematocrit percent in comparison with the control group and insignificantly in comparison with SeY supplementation.
13. Selenium yeast supplementation led to increase (P<0.05) overall mean of lymphocytes percent as compared to SeY plus Vit. E supplementation. However, overall means of monocytes, basophils, eosinophils and neutrophils percents didn’t prove any effects as a result of different supplementations.
14. Calves supplemented with the combination of SeY and Vit. E insignificantly improved digestibility coefficients of all nutrients when calves were fed starter concentrate diet. Concerning the commercial concentrate diet, the digestibility coefficients of crude fiber (CF) and ether extract were improved (P<0.05) when SeY plus Vit. E was supplemented. There were no significant effects for the SeY supplementation, while Vit. E supplementation declined (P<0.05) the digestibility coefficient of CF.
15. Total digestible nutrients (TDN) and digestible crude protein (DCP) didn’t significantly affect by different supplementations when calves were fed starter concentrate diet. Meanwhile, supplementation of SeY plus Vit. E improved (P>0.05) TDN and DCP when commercial concentrate diet was fed.