Further studies on Vitamins and the Reproductive Cycle of Ovaries In Cod (Gadus morrhua)

Abstract

The relations between vitamin B6, vitamin B12, biotin and total dry matter and the reproductive cycle of the ovaries in cod has been investigated. The stage of maturation or regeneration was expressed as the percentage ovary of the fish weight, and the cycle divided into 8 groups from the juvenile stage to the pre-spawning stage. Vitamin B6 showed a strong increase in the first stages, from 0.04 to 2.5 µg per g fresh weight. It remained on this level until spawning. Calculated on the basis of dry matter, the trend was the same and the corresponding values 0.23 to 8.5 µg per g. Vitamin B12 showed a significant decrease from 0.359 µg per g fresh weight in juvenile to 0.266 in the first stage of maturation. It then decreased slowly but significantly to 0.139 to drop just before spawning to 0.092 µg per g fresh weight. The corresponding values calculated on total dry matter were 2.35, 1.63, 0.46 and 0.38 µg per g. Biotin showed an increase in the first stages from 0.119 to 0.220 µg per g fresh weight. Just before spawning the concentration decreased to 0.132 µg per g fresh weight. The trend is similar to the change in dry matter, and calculated on this basis the values remained about 0.75 µg per g until the time of spawning, when it decreased to 0.55 µg per g. Total dry matter increased significantly from 15.3 % to about 30 % to decrease significantly just before spawning.