Thirty clinical normal Friesian calves (15 males and 15 females) were used in this study to reveal th: effect of animal age and sex on serum calcium, inorganic phosphorus levels as well as the relationship of the two parameters with the daily body weight gain.
Blood samples were taken on fixed day at monthly interval from the first month. Separated serum samples were analysed for calcium, inorganic phosphorus and Ca; ph ratio was recorded. Body weight of the calves was recorded monthly until the end of the experi mental period. The obtained results concluded that animal age has a sinificant effect on blood calcium, and inorganic phosphorus levels, while sex had no significant influence on these two para meters.
The maximum daily body weight gain in both sexes was observed during the fourth month, while the lowest gain was recorded between 5-7 months of age, then tend to be increased with the advance of age till reaches 1.03 kg. gain at 18 months of age.