RNA-seq reveals differentially expressed genes involved in the hypothalamus and pituitary function affecting divergent residual feed intake in slow-growing Korat chicken

Feed efficiency (FE) is crucial in poultry production due to the high costs of feed. Korat chicken (KRC), a slow-growing breed, is known for its unique meat flavor and nutritional value, with genetic variation in feed efficiency (FE). Since the brain parts, i.e., the hypothalamus and pituitary gland, act as a convergent and integrative center for multiple nutrient-related signals, understanding the genetic basis of neuronal signaling regulating FE is essential to improve the genetic potential of KRC. Thus, this study aimed to identify genes related to neuronal signaling that influence FE using RNA sequencing in the hypothalamus and pituitary gland from low and high residual feed intake (RFI) groups. RNA was extracted from 20 hypothalamic tissues of males of KRC in the low residual feed intake (low RFI; n=10) and high residual feed intake (high RFI; n=10) groups, and five RNA pools were created from 10 each group. A total of 10 transcriptome libraries were constructed, and candidate genes for FE traits were screened and identified. For the pituitary gland, total RNA was isolated from pituitary samples of 8 chickens from each group (LRFI or HRFI). To increase the quantity of RNA and reduce variation from dissection, an equal mass of RNA from 2 birds was pooled for each sample in each group, yielding a total of n = 4 pools for each of the LRFI and HRFI groups. Pools were defined according to ranked RFI values (e.g., pairs of samples with successive RFI values were pooled). Subsequently, a total of 8 transcriptome libraries were constructed (n=4/treatment), and candidate genes for FE traits were screened and identified.