ABSTRACT
Sixty growing Najedi ram lambs (23.5 kg BW: 3 months old) were divided randomly to 6 equal groups. Each group was fed on different (isonitrogenous) diet, being either high energy (2.79 Mcal ME/kg DM) or low energy (2.15 Mcal Me/kg DM), supplemented with either 0.5 or 10% poultry offal meal (POM) in replacement of an equal amount of soybean meal (SBM). Feeding was ad libitum for 15 weeks experimental period. Thyroid hormones levels in plasma were determined during the last 7 weeks of the experiment and were related to feed intake and body weight during the same period. Lambs fed high-energy diets showed higher (P < 0.01) levels of both thyroxine (T4) and triiodothyronine (T3) compared to those fed low-energy diets leading to lower T4 to T3 ratios. There was more conversion of T4 to T3 for more utilization of food by the lambs fed the 10% POM diet of the high-energy content.
