effects of thyroxin in ovo injection and post hatch arginine feed supplementation on performance and cold tolerance acquisition in broilers

two experiments were conducted to evaluate the effects of thyroxin in ovo injection and post hatch arginine feed supplementation on performance and cold tolerance acquisition in broilers. in experiment 1, a total of 2400 hatchings eggs were randomly assigned to four treatments: positive controls (intact or pricked with a needle), negative control (intact egg), injected with distilled water and injected with thyroxin. in experiment 2, a total of 240 day old male broiler chicks from the intact and injected with thyroxin treatment groups were assigned in a 2 × 2 factorial trial based on completely randomized design, with two level of injection (non-injection or injected with 65ng of thyroxin) and two type of diet (without arginine or 5 kg/ton arginine). in order to induce ascites in chicks, all of the chicks were exposed to 15°c from 14 to 42 d of age. the results showed that the second grade chicks and yolk sac weight were decreased (p