OSORIO, José Henry; SALAMANCA, Diana Marcela    PEREZ, Jorge Enrique. COMPARISON OF THYROID HORMONE LEVELS BETWEEN TWO LINES OF BROILERS. []. , 10, 2, pp.9-15. ISSN 1657-9550.

Objective: to establish reference values for TSH and free T₄ in two lines of broilers (Ross and Cobb), and also to compare the thyroid hormone levels in serum of those two lines. Materials and methods: after fasting, serum of one-hundred, 35 days of age broilers (50 Ross and 50 Cobb) was obtained, and TSH and free T₄ levels were measured using enzymatic immunoassay. Results: the TSH values for the Ross line (µUI/mL) were: average 0.00; minimum 0.06; maximum 0.34; and 0.07 standard deviation. For the Cobb line (µUI/mL) the values were: average 0.01; minimum 0.08; maximum 0.42; and 0.09, standard deviation. The P value for the F test is superior or the same as 0.05. As a consequence, there is no statistically significant difference with a confidence level of 95 %. for TSH between the two analyzed lines The free T₄ values for the Ross (ng/dL) line were: average 0.71; minimum 0.60; maximum 1.15; and 0.27 standard deviation, and the values found for the Cobb line were: average 0.76; minimum 0.20; maximum 1.26; and 0.28 standard deviation. The P value for the F test is superior or the same as 0.05. As a consequence there is no statistically significant difference with a confidence level of 95 %. for free T₄ between the two analyzed lines. Conclusion: levels of TSH and free T₄ are similar for the two lines tested, which can be attributed to a similar hormonal response they have due to the genetic selection they have undergone. Reference values for TSH and free T₄ are presented.

: metabolism; broilers; TSH; free T4.

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