Ad libitum feeding alters mRNA abundance in the ovarian cortex of broiler breeder hens

Abstract

Ad libitum feeding in broiler breeder (BB) hens causes reduced egg production, lower fertility and improper eggshell deposition. Restricted feeding (RF) is the only effective intervention available to normalize ovarian function and improve reproductive efficiency. This study aimed to assess the transcriptional changes in ovarian cortex of BB hens with free access to feed compared to those on a restricted feeding (RF) diet. RNA was isolated from the ovarian cortex of Cobb 500 pullets raised to 10 and 16 weeks of age on either a full-feeding (FF) or RF diet. Microarray analysis identified 386 differentially expressed genes (DEGs) between the two feeding groups at 16 weeks of age. Gene ontology enrichment identified overrepresentation of Neuroactive ligand-receptor interaction pathways, Cell adhesion molecules, Steroid hormone biosynthesis, and various KEGG pathways. From these groups, 46 genes were selected for follow-up validation by qPCR. The findings show that 33 of the 46 genes had significantly different abundance by age and/or feeding level. Most of these genes were repressed in RF hens and belonged to the steroid biosynthesis and neuropeptide signaling groups. The VIPR2 receptor was higher in the FF group leading us to hypothesize that VIP is an important regulator of small cortical follicles. Culture of cortical follicles with VIP increased Star, an indication of increased steroidogenic activity, although did not elevate Cyp11a1. These results offer insights and suggest the possible mechanisms and pathways responsible for the increases in cortical follicle growth associated with excess feed intake in BB hens.

Impact of In Ovo Leptin Injection and Dietary Protein Levels on Ovarian Growth Markers and Early Folliculogenesis in Post-Hatch Chicks (Gallus gallus domesticus)

“…We found that the level of dietary protein alters the mRNA transcripts of HPG-axis genes, particularly in the ovaries of early life broiler chicks, potentially affecting future folliculogenesis. Our results are consistent with those of other studies and suggest that maternal or neonatal imbalanced nutritional intake influences folliculogenesis and reproduction during the pubertal and prepubertal stages in animals, including BB hens [10,44,45].…”

“…Similarly, in BB hens fed ad libitum, ovarian expression of the steroidogenic markers cytochrome P450 aromatase (CYP19A1) and CYP11A was reported to be higher and was associated with increased follicular development at week 16 [16]. Another study revealed that nutrition modifies ovarian gene expression, with feed restriction significantly suppressing most steroid biosynthesis and neuropeptide-related genes in BB hens at 10 and 16 weeks of age [10].…”

“…Obesity and higher abdominal fat deposition are closely associated with elevated plasma glucose, insulin, cholesterol, triacylglycerol, and phospholipid levels in BB hens [6,7]. Overfeeding alters the transcription of ovarian growth markers as well as plasma progesterone and estradiol levels, resulting in hyper-recruited prehierarchical follicles and irregular follicular hierarchy in adult birds [6,[8][9][10]. This ovarian phenotype in BB hens resembles a human condition known as polycystic ovary syndrome (PCOS), which is associated with obesity, abnormal folliculogenesis and ovulation, and poor reproductive efficiency [7,11,12].…”