COMPARACIóN DE LOS NIVELES DE HORMONAS TIROIDEAS ENTRE DOS LíNEAS DE POLLO DE ENGORDE

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.