With the development of a large-scale and intensive production industry, the number of laying hens in China is rapidly increasing. Oils, as an important source of essential fatty acids, can be added to the diet to effectively improve the production performance and absorption of other nutrients. The present review discusses the practical application of different types and qualities of oils in poultry diets and studies the critical effects of these oils on production performance, such as the egg weight, feed intake, feed conversion ratio (FCR), and various egg quality parameters, including the albumen height, Haugh units, yolk color, and saturated/unsaturated fatty acids. This article reviews the effects of different dietary oil sources on the production performance and egg quality of laying hens and their potential functional mechanisms and provides a reference for the selection of different sources of oils to include in the diet with the aim of improving egg production. This review thus provides a reference for the application of oils to the diets of laying hens. Future studies are needed to determine how poultry products can be produced with the appropriate proper oils in the diet and without negative effects on production performance and egg quality.

In this study, soybean oil, lard and mixed oils were added to the feed in two concentrations (1.5% and 3% of each), resulting in six experimental groups. The control group was fed with a base diet without additions, and used to compare the effects of feeding on production performance and egg quality of laying hens. The results demonstrated that: (1) the 3% supplemented-oils or lard group showed a decrease in laying rate; (2) 1.5% and 3% added-lard significantly increased the total amount of unsaturated fatty acids in eggs, compared to the control group; (3) 1.5% and 3% soybean oil increased the content of mono/polyunsaturated fatty acids, cholesterol, phospholipids and choline in eggs; (4) glutathione peroxidase (GPx) and superoxide dismutase (SOD) contents were increased in all groups, being the most evident in the lard-treated group; (5) all experimental groups showed an increase in the content of essential and non-essential amino acids in albumen; (6) 3% oils, especially the mixed oils, damaged the structure of globules of cooked egg yolks. Therefore, the use of 1.5% soybean oil in the feed diet of Hyline brown hens resulted in the most adequate oil to ensure animal health and economic significant improvements in this experiment.

Since the early 2000s, the poultry industry in our nation has steadily progressed towards a larger scale and increased intensification. However, the growing demand for animal-based protein, combined with significant increases in feed ingredient costs, presents substantial challenges to the advancement of egg production. The regulation of feed utilization efficiency in laying hens is a complex process, influenced by various factors including the farming environment, feed composition, microbial ecosystems, and hormonal dynamics. The feed conversion rate in laying hens not only serves as a critical indicator of agricultural productivity but also highlights the significant impact of molecular technologies in improving feed efficiency. These technological advancements have enhanced the precision and effectiveness of breeding practices while providing substantial support for optimizing feed management, improving production metrics, and promoting sustainable agricultural practices. This comprehensive synthesis of factors, regulatory pathways, and cutting-edge molecular methodologies establishes a biological framework for future breeding strategies. Notably, this review uniquely emphasizes the pivotal role of modern molecular biology techniques—such as genomic selection, transcriptomic profiling, and gene-editing tools—in decoding feed conversion efficiency (FCE), contributing to broader goals of agricultural sustainability by balancing productivity gains with eco-friendly and cost-effective egg production.

Eggs, recognized as a “complete nutritional food”, constitute a crucial source of high-quality protein and maintain an essential position in China’s animal protein supply system. However, extended storage periods induce biochemical degradation, including protein denaturation, air cell expansion, and microbial growth, substantially affecting both food safety and nutritional value. As consumer demand for food quality assurance increases, research in egg freshness evaluation has made substantial progress. While existing studies have focused on isolated detection methods for egg freshness, there remains a critical gap in systematically integrating multidisciplinary approaches and evaluating their synergistic potential for comprehensive quality assessment. This review systematically categorizes conventional and emerging detection methodologies, including sensory assessment, physical characterization, chemical analysis, and intelligent detection technologies. The paper presents a comprehensive analysis of current research developments while offering perspectives on practical applications and future directions for egg freshness evaluation systems.

Lipids are commonly incorporated into the diets of laying hens at a rate of 1% to 2% during production. However, the effects on egg quality can vary based on the source and timing of lipid addition. Hence, this experiment was conducted to investigate the impacts of adding the same concentration of soybean oil, lard, and mixed oils (1.5%) to the daily feed of layer during two feeding periods. This study aimed to assess the changes in nutritional composition and functional properties and offer valuable insights to determine suitable types of oils and fat. In this study, the experiment was conducted in two test periods, 7 days and 21 days after the addition of the lipids, to assess the effects on the nutritional composition and functional properties of eggs. The study revealed the following results: (1) Changes in the yolk’s nutritional composition. Compared to the 7-day addition period, the inclusion of lard significantly increased the unsaturated fatty acids after 21 days; (2) Changes in the albumen’s nutritional composition. Compared to the 7-day addition period, the inclusion of lard and mixed oils significantly reduced the essential and nonessential amino acids after 21 days; (3) Changes in the functional characteristics of the eggs. After 21 days of addition, the eggs from the soybean oil group exhibited significantly higher foaming and emulsifying properties compared to the groups supplemented with lard and mixed oils; (4) Changes in the antioxidant capacity of the eggs. Compared to the 7-day addition period, the inclusion of all oils and fat significantly increased the superoxide dismutase (SOD) content in egg yolk after 21 days. The aim of this experiment was to provide valuable scientific data to assist producers in making informed decisions regarding the utilization of feeding oils.