Two hypotheses currently exist regarding to the determining factors for sexual development and differentiation in birds. One is based on the unbalanced sex chromosome, meaning that avian sex determination is dominated by ¡§Z-chromosome dosage¡¨. The other brings up (reconsider this) the key factor of ¡§W chromosome¡¨ which is a particular sex chromosome in female birds (ZW). In the previous studies, we constructed a female-subtract-male cDNA library before morphological gonad differentiation. After sequencing and annotation, a total of 279 expression sequence taqs (ESTs) were identified, with potentially higher expression levels in females. By utilizing quantitative RT-PCR, 16 potential ESTs and three marker transcripts (HINT1, FET1 and WDR36), which identified to be involved in sexual development at 3, 5, 7, 9 days post-coitum (dpc) was analyzed in chicken embryos. Results indicated that AGR2, CPT2, DUSP19, HINTW, LOC771368 and EY53070791 had higher expression levels in female than in male embryos at 3 and 5 dpc; FET1 expression level in female embryos gradually increased from 3 to 9 dpc. Moreover, both HINT1 and WDR36 were higher expressed in male than in female embryos across 3 to 9 dpc. However, HINT1 exhibited higher expression levels starting at early stage, whereas WDR36 at later stage. Next, we constructed HINT1-GFP fusion protein and overexpressed this protein in chicken B-cell line (DT40), resulting in upregulation of WDR36 expression. On the contrary, overexpressed HINTW-GFP fusion protein in DT40 cells had decreased WDR36 expression level. Moreover, we designed a small hairpin RNA by utilizing RNA interference technique to knockdown expression of HINTW, which resulted in WDR36 upregulation. Finally, we then estimated the regulation of WDR36 promoter activity through analyzing HINT1-GFP overexpression. Results had shown that HINT1-GFP can improve WDR36 promoter activity. Therefore, we suppose that HINT1 can regulate WDR36 transcription via WDR36 proximal promoter region. Ongoing HINT1 responsive element(s) must be identified to characterize whether HINT1 or HINTW regulates WDR36.

As activity levels of intensively managed broiler chicken vary over time, detailed knowledge on their influence is potentially useful to further adjust welfare assessment schemes. Therefore, this study investigated the influence of daytime and age on the performance of broiler chicken in two applied fear tests.On-farm studies were carried out in 14 flocks of intensively managed broiler chicken. A forced and a voluntary approach test were conducted during morning and evening hours and at three different ages (1: 6-12d; 2: 21-24d; 3: prior to slaughter). At each observation, avoidance distances (AD) and the number of animals voluntarily approaching (VA) an observer were collected.No significant correlation was found between daytime and AD or VA. When tested at different ages, daytime and VA were significantly correlated (1: r= 0.56*; 2: r= 0.40*; 3: r= 0.64*), but the results were not consistent. At three weeks the VA was found to be higher in the morning but at younger age and prior to slaughter, more birds approach an observer in the evening. Both, approach and avoidance peaked at three weeks and decreased prior to slaughter. Further, the effect of differing observer locations in the chicken house on the behavioural response of broiler chicken was studied. A higher proportion of birds voluntarily approached an unknown human in the area close to the main entrance door, but the avoidance behaviour was not affected.From the results of this study I conclude, that the time of assessment has no effect on avoidance or approach behaviour of commercial slow-growing broiler chicken. However, fear related behaviour changed depending on age. This makes the applied tests potentially applicable independent of daytime restrictions when performed with birds of the same age.