Although numerous studies reported the effects of heat stress in chickens, it was not investigated in the Transylvanian Naked Neck breed. In our research, Transylvanian Naked Neck chickens, 24 h after hatching, were heat-treated at 38.5 °C for 12 h. We compared the control and heat-treated adult chickens’ productivity parameters following 12 weeks of heat-stress at 30 °C. We found that the heat-treated layers had significantly higher egg production in heat stress, but in cockerels, the sperm quality did not differ significantly between the two groups. To detect the effect of heat-treatment on a molecular level, the expression of two heat-shock proteins and four heat-shock factors were analysed in the gonads of control and heat-treated chickens. We found that the expression level of HSP90 and HSF4 increased significantly in heat-treated female chicken gonads. Still, in adult females, the expression of HSF2 and HSF3 were substantially lower compared to the control. In adult heat-treated males, the HSP70, HSF1 and HSF3 expression levels showed a significant increase in both gonads compared to the control. We think that the presented significant differences in egg production might be related to the increased expression level of HSP90 and HSF4 in heat-treated female gonads.

As an alternative method for preserving female genetic material, the cryopreservation and orthotopic transplantation of day-old gonadal tissue have become well-developed techniques in a few poultry species. The aim of the present study was to apply these methods for the first time to domestic geese. Cryopreservation was accomplished using the previously developed vitrification technique. Native and frozen/thawed White Hungarian geese ovarian tissue was transplanted onto Grey Landes geese recipients. Both donors and recipients were less than 24 h old. The surgical protocol previously used in chickens needed to be modified regarding anaesthesia; ketamine, xylazine, and midazolam were administered partly intramuscularly and partly intravenously. After sexual maturation, the Grey Landes recipients were paired with White Hungarian ganders, and eggs were collected and hatched individually. The origin of the offspring was determined by phenotype- and microsatellite markers. Donor-derived offspring were obtained from native and frozen/thawed ovarian tissue transplantation, which had not been published earlier. The ratio of donor-derived progeny producing layers was 40% and 58% in native and frozen/thawed gonadal tissue transplantation, respectively. The highest rate of donor-originated progeny was 78.9%. Consequently, gonadal tissue transplantation appears to be a suitable method for preserving female genetic material in domestic geese; the technique is already implemented in Hungarian gene bank practice.

Orthotopic transplantation of ovarian tissue at one day of age is a promising solution for preserving female genetic material in avian species; using sterile recipients can ensure that all offspring are donor-derived. This study focuses on the suitability of the Mulard duck as a sterile recipient for Pekin duck donors and provides an investigation of the hormonal background. Firstly, native Pekin ovarian tissue was grafted into Mulard duck recipients, resulting in a 40% adhesion rate and follicular development in 50% of the adhered grafts. Secondly, the transplantation of cryopreserved ovarian tissue resulted in a 66% adhesion rate, with 33% of the adhered grafts showing follicular development. Ovulation occurred in 16% of the recipients with adhered grafts, but the eggs did not move into the oviduct. Estrogen levels were elevated in the recipients with adherence but were lower than in the control Pekin group, while progesterone levels remained unchanged. Consequently, recipients received buserelin acetate, a GnRH analogue, to stimulate follicular and oviductal activity. In this group, graft adhesion occurred in 31% of animals, and primordial follicle development in 25%. The hormonal levels of the recipients with adhered ovaries were elevated, but the GnRH analogue treatment did not affect the ovulation process. We conclude that while the Mulard duck shows potential as a sterile recipient in ovarian transplantation, several questions remain unanswered regarding the adequacy of follicular maturation and ovulation.