Abstract
The study about the relation between the body weights of Broilers chicks and chickens and their serum Triiodothyronine (T`-j) and Thyroxine levels is presented -for this purpose one hundred newborn chicks were used 50 o-f them were Hubbard cross breeds the others were Isa Brown cross-breeds. They were put into.four groups according to their body weights. The research period was eight weeks the di mention o-f the cages was 225 X 100 cm. They were -fed ad libitum. Every chick had its own number. At the end o-f every week (i.e. ?th, 14th, 21st, 35th, 42nd, 49th and 56th days) blood samples were taken and their weights were noted. As a -fact o-f normal development the animals were getting heavier gradually, however serum T^ ancj j levels were variable. The medium weight at the end o-f the -first week was 139.34 g. in the -first group, 152.20 g. in the second group, 145.20 g. in the third group and 135.60 g. in the -fourth group. At the end o-f the last week these values were 2133.00 g., 2266.80 g., 2243.04 gr and 2063.13 gr. Serum T^ levels were on -follows s 0.375 ng/ml, 0.264 ng/ml, 0.280 ng/ml and 0.277 ng/ml at the end o-f the first week and 0.622 ng/ml, 0.438 ng/ml, 0.472 ng/ml and 0.535 ng/ml at the end of the eighth week. Serum T4 levels were as follows s 1.100 %Kg, 1.005 %ffg, 1.008 %Mg, 0.910 %Mg at the end of the first week and 3.004 %ftg, 2.204 %Mg, 2.113 %Mg and 2.383 %Mg at the end of the last week. As a result a valuable correlation between the weights and serum T^ level was found (p<0.05 in the third week, p<0.01 in the eights week). In fact there was on meaningful correlation between serum T^ and j^ levels (p<0.01>, no significant correlation was seen between serum T. levels and the body weights.
