EFFECTS OF EGG STORAGE AND MATERNAL DIET ON BROILER BREEDER REPRODUCTIVE PERFORMANCE

Abstract

The purpose of this research was to identify biomarkers of early embryonic mortality (EEM) in broiler breeder chickens, and to elucidate the mechanisms by which egg storage and parental diet may influence egg biochemical composition and embryonic outcomes. The objective of the first study was to validate the use of Multiple Reaction Monitoring (MRM), a targeted mass spectrometry technique, on broiler breeder egg yolks, and to establish a lipidomic and metabolomic profile of eggs subjected to pre-incubation storage and early embryonic mortality. A discovery phase screened a total of 3706 lipid species across 26 lipid classes, as well as 693 metabolite species. Of the species screened, 510 lipid and 126 metabolite species were determined to be reliably detectable in broiler breeder egg yolk for samples with and without early embryonic mortality. Preliminary statistical analyses identified 58 lipid and 28 metabolite species significantly impacted by early embryonic mortality. This validated the use of MRM profiling for future experimentation, provided a base lipidomic and metabolomic profile for screening, and identified preliminary lipid and metabolite species that may be influenced by EEM. A subsequent exploratory phase analysis examined the impacts of egg storage and early embryonic mortality on broiler breeder yolk composition. A total of 277 lipidomic and metabolomic candidate biomarkers associated with storage were identified, indicating a robust impact of prolonged egg storage on yolk biochemical composition. Another 34 lipidomic and metabolomic candidate biomarkers were found to be related to early embryonic mortality, indicating a more specific influence of EEM. These findings provided candidate biomarkers of egg quality and offered mechanistic insight into how egg storage can influence yolk composition and embryonic viability. A second study was conducted to explore the effects of egg storage on embryonic gene expression in early development. Whole embryos from eggs stored for either 2 or 10 days were collected on day three of incubation. Reverse transcription-quantitative PCR (RT-qPCR) was performed to assess differences in mRNA levels between storage groups. Seven genes (TUBB1, ID2, CPT1A, CLTC, FABP2, GPX7, and PLK1) were significantly (p<0.05) up-regulated in the 10-day storage condition, implicating shifts in mitochondrial fatty acid oxidation, oxidative stress, cellular transport, and early developmental signaling in response to prolonged egg storage. This supported the lipidomic and metabolomic findings that pre-incubation egg storage has significant impacts on embryonic development. The final study aimed to explore the impacts of high oleic acid enriched soybean meal on broiler breeder reproductive performance. We hypothesized that a diet containing high oleic soybean meal could improve broiler breeder reproductive efficiency and potentially reduce instances of early embryonic mortality. Cobb 500 broiler breeder chickens were fed either a standard or high-oleic soybean meal diet. Egg production and early embryonic mortality were not impacted by diet. However, a significant diet x day interaction (p<0.001) revealed that fertility increased progressively in standard-diet birds but plateaued early in high-oleic birds, resulting in a significantly lower estimated fertility in the high oleic group by mid-trial. Although the findings did not support our initial hypothesis, they do support the use of dietary intervention as a means to alter reproductive outcomes in broiler breeder chickens. The results of these studies provide novel insight into how pre-incubation egg storage and dietary alteration can impact embryonic viability, egg quality, and overall reproductive success. Collectively, these findings may be used to inform commercial management strategies to improve broiler breeder reproductive performance.