Changes in the Oxidative Status of Dual-Purpose Hens Rearing in the Free-Range System during Cold, Thermoneutral and Hot Period.

This study aimed to assess the changes in the oxidative status of six genotypes of free-range laying hens during cold, thermoneutral, and hot periods by measuring the levels of lipid peroxidation (LPO), total glutathione (tGSH), and the activity of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in erythrocyte suspension, in relation with their egg production. Two identical experiments were conducted in two consecutive years. Thermal stress adversely affected the oxidative status of hens. The induced OS is expressed by an increase in LPO and the activities of antioxidant enzymes SOD and GPx during cold and hot periods and a decrease in CAT and tGSH during the cold period in both years. The factor "temperature period", compared to "year" and "genotype", had the most significant influence on all biochemical parameters (p < 0.001). Significant phenotypic correlations (p < 0.05) were detected among studied biochemical parameters, except between SOD and tGSH. The chicken genotypes showed differences in their susceptibility to OS and this had an effect on egg production­from 37.87% to 74.93%. The OS is genotypically specific and can play a significant role in determining welfare and egg production in free-range systems.

Comparative analysis of nutrient content and energy of eggs from different chicken genotypes.

BACKGROUND: Eggs are important foods in the daily diet of humans and have great biological activity and a high digestibility. Egg yolk is a good source of biologically active substances such as fatty acids, phospholipids, sterols and tocopherols. The eggs of seven chicken genotypes were analyzed for their chemical composition, and a detailed study of the lipids in egg yolk was conducted. RESULTS: Energy composition of the egg yolk and egg albumen was 29.06-30.51 MJ kg-1 and 19.77-20.93 MJ kg-1 respectively. Regarding their chemical composition: water ranged from 471.7 to 515.4 g kg-1 and 878.3-885.9 g kg-1 ; fat content in dry matter ranged from 607 to 647 g kg-1 and 6.7-11.6 g kg-1 ; protein varied from 302 to 331.7 g kg-1 and 823.6-892.5 g kg-1 ; ash ranged from 33.7 to 37.7 g kg-1 and 63.8-74.0 g kg-1 ; and nitrogen-free extracts ranged from 12.7 to 36.5 g kg-1 and 35.0-96.2 g kg-1 . The sterols and phospholipids in the yolk lipids were 16-26 g kg-1 and 59-127 g kg-1 . The main fatty acids in the lipids were oleic (39.1-47.3%) and palmitic (26.0-35.5%) acids. Cholesterol in the yolk lipids ranged from 15.9 to 25.9 g kg-1 . Phosphatidylcholine (389-573 g kg-1 ), phosphatidylethanolamine (219-355 g kg-1 ) and phosphatidylinositol (112-284 g kg-1 ) were the main phospholipids. The content of saturated fatty acids in the phospholipids was significantly higher than that in triacylglycerols. CONCLUSION: Small variations in the chemical composition of eggs from seven different genotypes were observed. Significant differences in the fatty acid compositions of the main classes of phospholipids and the triacylglycerol fraction were established. © 2019 Society of Chemical Industry.