The Effect of Tamoxifen on Some Reproductive Traits in Two Local Chicken Strains. 2. Tamoxifen and Productive Performance of Laying Hens

The present study was conducted to evaluate the responses of Tamoxifen (TAM) administration on sexual maturity, productive and reproductive performance and blood parameters in two local juvenile female strains. Ninety females from each of Gimmizah and Bandarah strains at four weeks of age were divided into three equal groups involving 30 chicks per each and injected intramuscularly with TAM twice a week through all experimental weeks. The first group was injected with 0.2 ml of sunflower oil and ethanol mixture (1:1, v/v) and served as a control, while the second and third groups were injected with 0.2 ml sunflower oil and ethanol mixture which contains 0.5 mg (0.5 TAM) and 1 mg TAM/Kg body weight (1 TAM), respectively. The experiment continued until 28 wks of birds' age. Highest significant (P≤0.05) body weight was recorded for birds group injected with 1 TAM compared with those for 0.5 TAM and control among all experimented ages. Besides, Gimmizah body weight hens were significantly heavier than Bandarah ones at 22 and 28 weeks of age. TAM treatment had no significant effects on feed consumption, mortality rate and egg weight. While, egg number and egg production percentage were significantly (P≤0.05) increased by TAM treatment compared with control group. Moreover, 1 and 0.5 TAM advanced the sexual maturity by 15 and 7 days, respectively as compared to control group. Besides, Bandarah hens were significantly lower and earlier than Gimmizah ones in egg number and age at first egg, respectively. Egg shell percentage and shell thickness were significantly higher in I TAM treatment than the other groups at 28 weeks of age. While, there were no significant differences between Gimmizah and Bandarah hens for all egg quality traits. Tamoxifen had no significant effects on egg shape index, Haugh unit, yolk (%), albumen (%), plasma cholesterol, calcium, GOT and GPT. Hematocrit and total lipids concentrations were significantly higher for all tamoxifen treated hens as compared to control, whereas, the significant increase in estradiol was observed in 1 TAM only compared to control. Tamoxifen enhanced relative weight of ovary at 17 and 28 weeks of age, while oviduct relative weight was significantly increased only at 17 weeks of age compared with the control group. Furthermore, Gimmizah hens had significantly (P≤0.05) higher ovary and oviduct percentage weights compared to those for Bandarah hens at 17 weeks of age only. Tamoxifen treatments had no significant influence on fertility and hatchability percentages. Injection of 1 TAM significantly increased hatched chicks weight compared with other groups. In conclusion, using 1 TAM advanced sexual maturity, improved egg number, egg production percentage, increased egg shell thickness, stimulated estrogen secretion and in turn increased ovary and oviduct percentages.