Table 1.
Composition of the layer hen feed.
Fig 1.
Weather trends across the 2022 grazing season.
(A) Daily average temperatures and total precipitation (B) Monthly average temperature and total precipitation and their comparison to the 30-year normal. *Signifies average monthly total precipitation that is greater than three standard deviations from the 30-year normal.
Table 2.
Characteristics of the soil by month1.
Fig 2.
Monthly forage composition and estimated hen forage intake.
(A) Illustrates the proportion and types of species that make up the monthly forage composition. (B) Height of forage before and after the hens grazed representing intake estimates across the year. *Pre-Graze height data not available.
Fig 3.
Seasonal changes in the forage quality and proximate analysis.
Means and standard error of the mean (SEM) are shown. (A) Forage proximate analysis data (B) Forage quality based on total digestible nutrients. ADF; acid detergent fiber, NDF; neutral detergent fiber, TDN; total digestible nutrients. Results of one-way ANOVA. a-e, means within a row with different letters significantly differ p < 0.05. † Indicates Low (45%), Medium (52%), and High (58%) quality forage based on TDN (% DM).
Table 3.
Physical characteristics of the eggs by month1.
Fig 4.
Significant changes in the yolk antioxidant profile.
Monthly means and SEM are shown. (A) Changes in the vitamin A and total carotenoid content (B) Changes in yolk vitamin E content. Results of one-way ANOVA. a-e, means within a row with different letters significantly differ (p < 0.05).
Table 4.
Egg yolk branched chain and conjugated linoleic fatty acids by month (g of fatty acid per 100 g of fresh egg yolk)1.
Fig 5.
Notable seasonal variations in the yolk FA profile.
Monthly means and SEM are shown. (A) Total SFA, MUFA, and PUFA values across the grazing season compared to the USDA expected value for total FA. (B) Palmitic, stearic, and total cholesterol across the season compared to expected USDA nutrient content. (C) Monthly changes in the n-6: n-3 ratio compared recommendation [17]. (D) Seasonal variations in the total and individual omega-3 fatty acid content. SFA, saturated fatty acids; MUFA, monounsaturated fatty acids, PUFA, polyunsaturated fatty acids; † USDA Cage-Free egg yolk expected nutrient value (25.45 g total fat, 6.86 g palmitic acid, 0.104 g stearic acid, and 1.08 g per 100 g) [40]. Results for the yolk SFAs, cholesterol, and the n-6:n-3 ratio as shown as mean ± SEM.
Fig 6.
Spearman correlation matrix illustrating significant relationships across monthly averages of egg nutrients, forage nutrients, environmental changes, and forage species parameters (p < 0.05).
The color intensity represents the strength of the correlation depicted: Blue represents R coefficient values between 0 to 1, while red represents values between 0 to –1. Text colors distinguish between sample type: purple for environment, blue for forage species present in the pasture, green is assigned to forage nutrients, and yellow to egg nutrients. total omega-3 fatty acids, total n-6; total omega-6 fatty acids, total SFA; total saturated fatty acids; TDN, total digestible nutrients.
Fig 7.
(A) sparse Partial Least Squares Discriminant Analysis (sPLS-DA) plot using egg nutrient parameters only showing separation and clusters based on month, with some overlaps. (B) Random Forest (RF) variable importance plot showing yolk nutrient parameters that differentiate between monthly collections. (C) sPLS-DA plot using forage and feed nutrient parameters only showing separation and clusters based on month, with some overlaps. (D) RF variable importance plot showing nutrient parameters that differentiate between monthly collections and layer hen feed. For sPLS-DA plots, ellipses are representative of 95% confidence interval regions. For RF plots, the y-axis represents nutrient parameters in order of importance for monthly classification (from top to bottom). The x-axis shows mean decrease accuracy, with a higher value indicating the importance of that phytochemical in predicting groups. Total SFA; total saturated fatty acids, total MUFA; total monounsaturated fatty acids, total PUFA; total polyunsaturated fatty acids, t. carotenoids; total carotenoids, total n-3; total omega-3 fatty acids, total n-6; total omega-6 fatty acids, t. phenolics; total phenolics.