EFFECTS OF VITAMIN-A AND VITAMIN-E ON BLOOD-PLASMA VITAMIN STATUS ANDDAILY BODY-MASS GAIN OF DIFFERENT FAT-TAILED SHEEP BREEDS

Ninety ram lambs of three Iranian fat-tailed sheep breeds including th e Shal breed (age: 4-6 months) in one experiment and the Sanjabi and B akhtiari breeds (6-9 months) in another experiment were assigned to fi ve groups of 5-7 lambs each to receive a basal diet plus different lev els of vitamins A and E supplementation. The groups received 0, 50 or 100 IU vitamin A/kg body mass (b.m.) and 0, 15 or 30 IU vitamin E/kg o f diet. In the vitamin A groups a constant level of 15 IU vitamin E an d in the vitamin E groups a constant level of 50 IU vitamin A suppleme ntation was provided. Blood plasma samples were taken at the beginning and at the end of the experiments and the concentrations of vitamins A and E were determined by high-performance liquid chromatography (HPL C). Vitamin A supplementation of the highest level (100 IU/kg b.m.) si gnificantly increased the retinol content of the blood plasma in the S hal (P < 0.01) and Bakhtiari (P < 0.05) breeds. The mild increase of r etinol concentration in the Sanjabi breed was not significant (P > 0.0 5). Vitamin A supplementation greatly decreased the alpha-tocopherol c ontent of the blood plasma in all three breeds (P < 0.01). It increase d the average daily body mass gain of lambs of the Shal breed (P < 0.0 1) but decreased that of Bakhtiari lambs (P < 0.05). Supplementation o f vitamin E mildly decreased the retinol content of the blood plasma i n all the breeds and the decrease was statistically significant CP < 0 .05) for the Shal breed at the highest dose level. Vitamin E supplemen tation greatly increased the alpha-tocopherol concentration of the blo od plasma in all the breeds (P < 0.01-0.001). It decreased the average daily body mass gain of the Shal breed (P < 0.001) but improved it in the two other breeds. That increase was statistically significant (P < 0.05) in the Bakhtiari breed. It was concluded that the Shal breed g ave a better response to vitamin A supplementation while the Sanjabi a nd Bakhtiari breeds to vitamin E. This indicates that fat-tailed breed s have dissimilar requirements for vitamins A and E supplementation. A higher level of vitamin E intake is required for raising the alpha-to copherol content of the blood plasma above the level critical for shee p (0.8 mu g/ml).