The effect of in-ovo injection of L-thyroxine and triiodothyronine in broiler breeder eggs on hatchability and broiler performance

In this research determine to effect of in – ovo injection of L-thyroxine and triiodothyreonine to fertile broiler eggs on hatchability, embryo mortality, chick quality and broiler performance. On the first stage the 600 fertile eggs used in this experiment were obtained from a Cobb-500 broiler breeder flock of 40 weeks of age. Treatments were following: 1) control grup, without injection (250 eggs), 2) group injected with 25 ng triiodothyreonine (T3) per egg in 0.1 ml physiologycal saline solution, 3) group injected with 50 ng L-throxine (T4) per egg in 0.1 ml physiologycal saline solution. All treatments are incubated in standart condition. Upon hatch, embryo mortality, hatchability, hatching time, weight, lenght and rectal temperature of newly-hatched chicks, yolk sac and without yolk sac body weight were measured. On the second stage for all control and T3 groups 4 replicate and 20 chicks per replicate, for T4 group 4 replicate and 15 chicks per replicate were transferred to experimental house and reared for 6 weeks (42 days). Live weight and feed intakes were measured for every each weeks and then weight gain and feed conversion ratio were calculated. The result of the research injection of T3 and T4 had no significant effect (P>0.05) on hatchability, rectal tempereture and without yolk sac body weight, hatching time, chick weight and lenght and yolk sac significantly (P<0.05) effected. Injection of T4 has the earliest hatching. The highest chick weight and yolk sac weight determined in T3 group and the highest chick length detected in T4 group. Also there were no significant effect (P<0.05) on feed conversion ratio, carcas properties and organ-related properties except relative liver weight. Chicks that received in – ovo injection of T4 had better body weight (0 – 6 weeks), wieght gain (1 – 3 weeks) and feed intake (1 – 3 weeks) compered with control group. In conclusion, the injection of L-thyroxine and triiodothyreonine showed that have positive effect on some incubation and broiler performance properties. In this regard, in – ovo injection of L-thyroxine and triiodothyreonine may suggested as a method increase to incubation performance and the development performance.