Basal Steroid Hormone Profiles and Reproductive Organ Development of the Native and Commercial Laying Hens in Different States of Egg Production

Abstract

Basal steroid hormone profiled in plasma of the chicken changed according to states of egg production and degrees of oviduct development. Whereas the levels of basal progesterone and estradiol showed a clear connection with the he-day egg production, the levels of testosterone and progesterone were more likely involved with the degree of oviduct development. The hen with its hen-day egg production record above 80% (Good layer) had higher (P<0.05) concentration of progesterone and estradiol than the hen with its egg production record below 25% (Layer) and the hen which laid no egg at all (Nonlayer). When a comparison was made between the 2 breeds within the same group of Good layer, it was found that the native Good layer had lower testosterone and progesterone concentrations as well as lower oviduct weight than the commercial Good layer (P<0.05). The coincidence indicated a probable involvement of the two hormones in growth and development of the oviduct. States of development of the ovary and oviduct were also related to states of egg production. It was clear that the Good layer always had heavier and longer oviduct than the Layer and the Nonlayer (P<0.05). Despite holding the same good egg production record, the native Good layer tended to have lower degree of the oviduct development than the commercial Good layer, but only the oviduct weight that the significant difference (P<0.05) was observed. The numbers of small-sized follicles (diameter < 2 mm.) of the hens in different states of egg production or of different breeds were comparable (P>0.05). The numbers of medium-size (diameter 2-8 mm.) and large-size (diameter > 8 mm.) follicles tended to increase with the hen-day egg production. The native hen also showed a trend of having fewer number of the medium-sized and large-sized follicles. The differences were, however, not significant (P>0.05).