The effect of new monochromatic light regimes on egg production and expression of the circadian gene BMAL1 in pigeons1.

We examined the effect of monochromatic light supplementation on pigeon reproductive performance and on the expression of the brain and muscle aryl hydrocarbon receptor nuclear translocator-like (BMAL1) protein in the hypothalamic-pituitary-gonadal (HPG) axis. White King pigeons were selected randomly from 4 lofts (510 pairs/loft) with 3 subgroups/loft. The lofts were exposed to one of 4 light treatments for 3 months administered in the morning and evening as follows: blue light (480 nm), green light (540 nm), red light (660 nm), and control white light. The laying rate, fertility rate, and birth rate were recorded. After 3 months, 48 birds were selected randomly from the 4 lofts (6 females and 6 males from each loft), sacrificed, and the HPG axis was isolated. Following exposure to red light, laying rate was greater than the control group (P = 0.013), but there were no significant differences in the fertility rate (P = 0.41) or birth rate (P = 0.66). Expression of BMAL1 in the hypothalamus was unaffected by the light regime but was greater in the pituitary of females exposed to red light (P = 0.046) and in the pituitary of males exposed to the control white light (P = 0.059). The change in BMAL1 expression in the pituitary of females was negatively correlated with birth rate in monochromatic light (P = 0.021). We suggest that reproductive performance of pigeons is improved by light supplementation in the morning and evening. According to these data, 100 pigeons exposed to red light could lay 26.68 more eggs per month than the control group. Additionally, BMAL1 expression in the HPG axis of pigeons exposed to monochromatic light correlated with birth rate.

Developmental changes in IGF-I and MyoG gene expression and their association with meat traits in sheep.

In the present study, real time-polymerase chain reaction was applied to analyze the expression of IGF-I and MyoG genes in Hu sheep longissimus dorsi at different growth stages and their association with meat traits. Expression of the IGF-I gene in Hu sheep differed significantly between males and females at the two day-old (0.01 < P < 0.05), one-month old (0.01 < P < 0.05), and three month-old (P < 0.01) stages. IGF-I gene expression in male longissimus muscles was higher than that of females at all growth stages, except for the three month-old stage. There was no significant difference (P > 0.05) between males and females at any growth stage in expression of the MyoG gene. MyoG gene expression in male longissimus muscles tended to be higher than that of females at all growth stages, except for the six month-old stage. IGF-I gene expression was significantly and positively correlated with live weight (P < 0.01) and carcass weight (0.01< P < 0.05), and was non-significantly positively correlated with net meat weight (P > 0.05). In contrast, MyoG gene expression was non-significantly and positively correlated with live weight, carcass, and net meat weight (P > 0.05). Carcass traits showed highly significant positive correlations (P < 0.01). Furthermore, expressions of IGF-I and MyoG genes showed highly significant positive correlations (P < 0.01). We conclude that the expressions of IGF-I and MyoG genes are significantly and positively correlated with early muscle traits of Hu sheep.