Differential expression of ASIP transcripts reveals genetic mechanism underpinning black-tail independence from body plumage in yellow-bodied chickens.

The genetic foundation of chicken body plumage color has been extensively studied. However, little attention has been paid to the inheritance patterns and molecular mechanisms underlying the formation of distal feather colors (tail and wingtip). Differences in these colors are common; for example, the Chinese Huiyang Beard chicken has black tail feathers, but yellow body plumage. Here, the hybrid offspring of Huiyang Beard and White Leghorn chickens were used to study the inheritance patterns of tail-feather color. The expression levels of pigment genes in differently colored feather follicles were analyzed using quantitative real-time PCR. The results showed that genetic regulation of tail-feather color was independent of body-plumage color. The Dominant White locus inhibited eumelanin synthesis in tail feathers without affecting the formation of yellow body plumage, whereas the Silver locus had the opposite effect. The expression of agouti signaling protein (ASIP) gene class 1 transcripts was significantly lower in black tail-feather follicles than in yellow body follicles, whereas tyrosinase-related protein 1 (TYRP1) gene expression was significantly higher in black tail feathers. These differentially expressed genes were confirmed to exert an effect on eumelanin and pheomelanin formation in feathers, thus influencing the regulation of chicken tail-feather color. In conclusion, this study lays the foundation for further research on the genetic mechanisms of regional differences in feather color, contributing to a better understanding of plumage pigmentation in chickens.

Effects of Glycine Supplementation in Drinking Water on the Growth Performance, Intestinal Development, and Genes Expression in the Jejunum of Chicks.

Glycine, the most basic amino acid found in nature, is considered an essential amino acid for chicks. However, the precise understanding of high concentrations of glycine's significance in promoting the growth performance of chicks, as well as its impact on intestinal development, re-mains limited. Consequently, the objective of this study was to investigate the effects of glycine supplementation in drinking water on growth performance, intestine morphology, and development in newly hatched chicks. In this study, 200 newly born chicks were selected and pro-vided with a supplementation of 0.5%, 1%, and 2% glycine in their drinking water during their first week of life. The results revealed that glycine supplementation in drinking water could significantly increase the average daily gain of chicks from days 7 to 14. Furthermore, a significant difference was observed between the group supplemented with 1% glycine and the control group. Concurrently, this glycine supplementation increased the villus height and the ratio of the villus height to crypt depth in jejunum on both day 7 and day 14. Glycine supplementation in drinking water significantly affected the mRNA expression level of the ZO-1, GCLM, and rBAT genes in jejunum, which may have certain effects on the mucosal immune defense, cellular antioxidant stress capacity, and amino acid absorption. Overall, the findings of this study indicate that glycine supplementation in drinking water can enhance the growth performance of chicks and promote their intestine development.

Chicken LEAP2 Level Substantially Changes with Feed Intake and May Be Regulated by CDX4 in Small Intestine.

Ghrelin O-acyltransferase (GOAT), ghrelin, and GHSR have been reported to play important roles that influence feed intake in mammals. LEAP2, an endogenous antagonist of GHSR, plays an important role in the regulation of feed intake. However, chicken ghrelin has also been reported to have an inhibitory effect on feed intake. The role of the GOAT-Ghrelin-GHSR-LEAP2 axis in chicken-feed intake remains unclear. Therefore, it is necessary to systematically evaluate the changes in the tissue expression levels of these genes under different energy states. In this study, broiler chicks in different energy states were subjected to starvation and feeding, and relevant gene expression levels were measured using quantitative real-time PCR. Different energy states significantly modulated the expression levels of LEAP2 and GHSR but did not significantly affect the expression levels of GOAT and ghrelin. A high expression level of LEAP2 was detected in the liver and the whole small intestine. Compared to the fed group, the fasted chicks showed significantly reduced LEAP2 expression levels in the liver and the small intestine; 2 h after being refed, the LEAP2 expression of the fasted chicks returned to the level of the fed group. Transcription factor prediction and results of a dual luciferase assay indicated that the transcription factor CDX4 binds to the LEAP2 promoter region and positively regulates its expression. High expression levels of GHSR were detected in the hypothalamus and pituitary. Moreover, we detected GHSR highly expressed in the jejunum-this finding has not been previously reported. Thus, GHSR may regulate intestinal motility, and this aspect needs further investigation. In conclusion, this study revealed the function of chicken LEAP2 as a potential feed-intake regulator and identified the potential mechanism governing its intestine-specific expression. Our study lays the foundations for future studies on avian feed-intake regulation.