Abstract
Simple SummaryThe effect of oral supplementation of Tamoxifen on productive and reproductive efficiencies and carcass characteristics of two broiler breeds was investigated in the current study. Tamoxifen supplementation can improve growth performance and carcass efficiency of broilers without changing the sex hormonal profile, however, treatment of broiler chicken with Tamoxifen in different doses caused a gradual decrease in follicle production rate and eventually led to an increase of the atretic follicles in different stages of atresia. Further research is required to estimate the best concentration required for each breed.This research was aimed at estimating the effect of oral supplementation of Tamoxifen on productive efficiency, carcass characteristics, hormonal profile and gonadal structure of two broiler breeds. One hundred and eighty chicks of each breed of Avian48 and Arbor Acres were divided into three groups: control group; TAM10 group, supplied with 10 mg Tamoxifen/kg of body weight at 3, 5, 7 and 9 days of life; and TAM20 group, supplied at the same intervals with 20 mg Tamoxifen/kg of body weight. Both levels of Tamoxifen improved productive performance at early ages, but Arbor Acres produced better results with TAM20 levels than TAM10, while Avian48 breeds reacted adversely. On the contrary, Tamoxifen supplementation significantly decreased feed intake and feed conversion (after the first two weeks of life) compared to control with a higher level of decrease reported for TAM20 treatments than TAM10 and for Arbor Acres compared to Avian48 breed. Carcass traits were not affected significantly with Tamoxifen supplementation compared to control although Arbor Acres responded better to TAM20 and Avian48 for TAM10. With regard to the effect of Tamoxifen (TAM) on sex hormones, it could be concluded that TAM10 treatments showed a stimulating effect on the level of such hormones as compared with the TAM20 group with the most favourable results being clearly detectable in 42-day-old birds although both concentrations of Tamoxifen did not differ significantly from control. However, treatment of broiler chickens with Tamoxifen in different doses caused a gradual decrease in follicle production rate and eventually led to an increase of the atretic follicles in different stages of atresia. Finally, we can conclude that Tamoxifen supplementation can improve performance and carcass efficiency of broilers without changing the hormonal profile, however much research is required to estimate the best concentration required for each breed.
Highlights
Oestrogen plays an important role in bird sex differentiation, which is essential for the growth of ovaries and the regulation of the proliferation of the left gonadal cortex [1]
This experiment was designed to determine the effect on performance and carcass traits of different broiler breeds (Avian48 and Arbor Acres) of oral administration treated with different levels of aromatase inhibitor (Tamoxifen) at an early age
The Avian48 breed attained higher body weight, carcass weight, dressing percentage and percentage carcass cuts compared to the Arbor Acres breed except for thigh percentage and giblets weights that were higher in the Arbor Acres breed
Summary
Oestrogen plays an important role in bird sex differentiation, which is essential for the growth of ovaries and the regulation of the proliferation of the left gonadal cortex [1]. 17b-Hydroxysteroid dehydrogenase and aromatase enzymes that are responsible for converting androgens to estradiol-17b are detectable only in the gonads of female embryos [2]. Oestrogens cause their effects in target cells through oestrogen receptors (ERs) located in the ovary and oviduct and in different tissues including the pituitary gland and hypothalamus [3]. Low doses of TAM advanced ovarian and oviductal development, increased oestrogen and androgen in plasma, and induced early egg laying in hens [6,7]. The various administration techniques of Tamoxifen were studied: in-ovo inoculation [9], per os in gelatine capsules [15] and intra muscular injection as well as the use of different preparation doses, e.g., 0.5; 1.0; 5.0; 10.0 or even 25 mg/kg body weight
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