title: Effect of age and season on the thyroid hormone activity of Mizoram strain female mithun (Bos frontalis).
abstract: OBJECTIVE
  The aim of the present study was to generate baseline data on the normal values of the thyroidhormone (TH) activity as well as their correlation with age and season.
  
  
  METHODS
  Blood samples (10 ml) were collected from jugular vein of 30 female mithun's of three different age groups viz. Calves (6 months to 1 year), heifer (1-3 years) and adult (above 3 years) during the three season's viz. Monsoon, winter and spring of a year. The serum was analyzed for thyroid stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4) activity.
  
  
  RESULTS
  The result showed a significantly (p<0.05) a higher T3 level in heifers followed by adults and calves and higher T4 level in adults followed by heifers and calves in all the seasons. The TSH level was higher in heifers in all the seasons. The winter season recorded higher level of T3, T4, and TSH as compared to the other seasons of a year.
  
  
  CONCLUSIONS
  The TSH and T3 level were the highest for aheifer, whereas T4 level was the highest for adults inall the season. Furthermore, the higher level of TH was observed in winter season. The increased level of the TH during the winter season signifies their calorigenic effect. Similarly in heifers, the increased T3 concentrations show its importance in reproductive physiology and its association with ovarian activity. This indicates that age and season have aprofound effect on TH activity of Mizoram strain female mithun.
authors.affiliation: Department of Veterinary Physiology and Biochemistry, College of Veterinary Sciences and A.H., Central Agricultural University, Selesih, Aizawl, Mizoram, India.
authors.lastname: Lalsangpuii
authors.affiliation: Department of Veterinary Physiology and Biochemistry, College of Veterinary Sciences and A.H., Central Agricultural University, Selesih, Aizawl, Mizoram, India.
authors.forename: M Ayub
authors.initials: MA
authors.lastname: Ali
authors.affiliation: Department of Medical Laboratory Technology, Regional Institute of Paramedical and Nursing Sciences, Mizoram, India.
authors.forename: L Inaotombi
authors.initials: LI
authors.lastname: Devi
authors.affiliation: Department of Veterinary Physiology and Biochemistry, College of Veterinary Sciences and A.H., Central Agricultural University, Selesih, Aizawl, Mizoram, India.
authors.forename: Parthasarathi
authors.initials: P
authors.lastname: Behera
authors.affiliation: Department of Medical Laboratory Technology, Regional Institute of Paramedical and Nursing Sciences, Mizoram, India.
authors.forename: Lalsanglura
authors.initials: L
authors.lastname: Ralte
keywords: age; mithun; season; thyroid hormone; thyroxine; triiodothyronine