ANBAR JOURNAL OF AGRICULTURAL SCIENCES

Abstract

This experiment was conducted to examine the effects of injected gibberellic acid GA3 in subcutaneous of hens neck and supplemental vitamin D3 to control basal diet on productive performance and egg shell thickness ,relative weight of egg shell of aged laying hens. Two hundred and seventy Lohmann Brown laying hens at 73 weeks of age were randomly assigned to three treatments groups. Each treatment consist of three replicates (30 hens / replicate). The treatments were : T1 control were injected subcutaneous with 0.2 ml / kg of body weight of ethanol: sesame oil solution, T2 and T3 were injected subcutaneous with 0.2 ml / kg of body weight of ethanol: sesame oil solution which contained 400 µg GA3/ kg of body weight /week during 8 weeks (treatment period) and allowed without injection for 4 weeks (recovery period). During the treatment and recovery periods all the hens of treatments were fed the control basal diets, only T3 supplemented with 500 IU vitamin D3 / kg diet during the treatment period (8 weeks).
The results showed a significant improvement in egg production (H.D%), egg mass and feed conversion ratio, whereas, feed intake and egg weight were decreased significantly for hens in T2 and T3 compared with those in T1 during both periods of experiment (treatment and recovery period). Hens that received T2 or T3 tended to increased the relative weights of eggshell and shell thickness compared with hens received T1during the period of treatment and recovery.
We can concluded that gibberellic acid GA3 injection alone or with VD3 supplementation to diets improve some of productive parameters especially the relative weights of eggshell and shell thickness of aged laying hens.