An experiment was conducted to investigate pH, osmolality, and the concentration of ammonia, total protein, glutamine and glutamic acid in follicular fluid at different developmental stages (<2, 3–4 and 5–6 mm in diameter) and serum of porcine. The concentrations of ammonia and total protein content were determined with the catalyzed indophenols reaction and the Bradford assay method and read on a spectrophotometer set at 625 and 595 nm, respectively. Glutamine and glutamic acid concentrations were determined by HPLC. The pH value was lower (P<0.05) but osmolality was higher (P<0.05) in follicular fluid than in serum. The concentration of ammonia was lower (P<0.05) in follicular fluid than in serum. On the other hand, glutamine and glutamic acid concentrations were higher (P<0.05) in the follicular fluid than in serum. The pH increased and osmolality decreased with increasing follicle size, and protein content was almost similar in small, medium and large follicular fluid. Ammonia, glutamine and glutamic acid concentrations decreased (P<0.001) as follicular size increased. During early follicular development ammonia and amino acids were synthesized for high metabolic breakdown of protein and gradually decreased due to metabolism of ammonia and glutamic acid to glutamate.