S. N. Kalita

Postnatal Gross Morphological and Histoenzymic Studies on the Thyroid Gland of Assam Goat

The thyroid gland was composed of right and left lateral lobes connected by a narrow isthmus. The location of the isthmus over the trachea varied in male goats which ranged from 4th to 9th tracheal rings. Various biometrical parameters viz. length, width, thickness and weight of the thyroid gland showed a highly significant (P<0.01) increase between various age groups as well as between the thyroids of right and left sides of the body in Assam goats. Accessory thyroid tissue was not observed in any of the male goats. Different biometrical parameters of the isthmus showed an increasing trend with the advancement of age and the variations were found to be highly significant (P<0.01) between various age groups, except in respect of their weight. The activity of LDH in the follicular epithelium of the thyroid gland varied from weak to intense from 4 to 10 months of age (groupsIII to VI). However, MDH showed a strong activity in these cells at birth (group-I), which was reduced to moderate in 4 month old kids (group-III) and again elevated in older goats. The enzymic activity of G-6-PDH was variable from mild to moderate in the male goats. The intertubular stroma of the thyroid gland showed no activity for MDH and G-6-PDH in all the age groups. But a mild activity of LDH enzyme was seen in goats from 6 month of age (group-IV) onwards.

Post Natal Changes in the Concentration of certain Serum Biochemicals, Metabolic and Steroid Hormones in Male Assam Goats (Capra hircus) from Birth to Ten Months of Age

The mean concentration of blood glucose showed an increasing pattern with advancing age in the male Assam goats ranging from 39.32 ± 0.12 mg percent at birth to 51.92 ± 0.05 mg percent in 10 months old bucks. Serum cholesterol concentration showed a declining trend that varied from 108.93 ± 1.35 mg percent at birth to 62.23 ± 0.66 mg percent in 10 months old goats. Similarly, the levels of serum total protein increased from 3.96 ± 1.35 to 8.16 ± 0.02 g percent at birth and at 10 month of age, respectively. The serum thyroid hormones showed a declining trend in the male Assam goats with increasing age. The mean concentrations of Triiodothyronine (T3) and Thyroxine (T4) were recorded as 1.65 ± 0.03 and 114.38 ± 0.62 ng/ml at birth and 0.81 ± 0.01 and 24.47 ± 0.31 ng/ml at 10 months of age respectively. On the other hand, serum concentrations of testosterone hormone raised from 0.11 ± 0.01 ng/ml in 2 months old kids to 1.13 ± 0.01 ng/ml in the goats at 10 month of age. Testosterone could not be estimated in the serum of day-old kids because the level was too low to measure. Serum concentrations of all the hormones showed a highly significant (P<0.01) variation between different age groups under study.