GROSS MORPHOLOGY AND ENCEPHALIZATION QUOTIENT OF BRAIN IN MALE AND FEMALE VANARAJA CHICKENS AT DIFFERENT AGES

One hundred fifty day-old sexed Vanaraja chicks (75 male + 75 female) were taken as experimental birds. Dissection of cranium was performed carefully and study of gross morphology of brain was undertaken at different ages in male and female birds. The brain in situ appeared like a ‘spade’ symbol in playing card but it appeared rather wider and globular in both sexes. The cerebrum varied from pear to oval or even globular in shape in both sexes. On dorsal view, the cerebral hemispheres appeared moderately convex and smooth surfaced. On ventral surface, ill-developed olfactory lobes were observed anteriorly on either side of the median fissure in both male and female Vanaraja birds. The hippocampus was located transversely to the posterior one third parts of both cerebral hemispheres. Duncan’s EQ ranged from 5.801 ± 0.514 (T3-Male) to 5.944 ± 0.451 (T1-Female) on 21st day. There was significant decrease (p<0.05) in EQ from Day 21 to 42 across all the groups. On 84th day, the range of EQ was 1.346 ± 0.115 (T3-Male) to 1.444 ± 0.114 (T1-Female). In case of Cuvier’s EQ, on 21st day the value ranged from 35.079 ± 0.288 (T2-Male) to 36.531 ± 0.312 (T3-Female). There was significant reduction (p<0.05) in Cuvier’s EQ value from Trial-I (21st day) to Trial-II (42nd day). Again, a significant decrease in EQ value was evident from Trial-III (63rd Day) to Trial-IV (84th Day). On 84th day, the EQ ranged from 15.607 ± 0.123 (T3-Male) to 16.038c ± 0.125 (T2-Male). Duncan’s formula had very high correlation coefficient with brain length (0.915). There was also very high degree correlation between brain weight and body weight (0.963). Brain weight and neuronal size are also highly correlated (0.902). Neuronal size and brain volume are also having a high correlation (0.902). The EQ values had medium correlation with neuronal size (0.701 for Cuvier’s Formula and 0.713 for Duncan’s formula). Duncan’s and Cuvier’s value had a very high degree of correlation (0.998).