Supplementation of laying-hen feed with annatto tocotrienols and impact of α-tocopherol on tocotrienol transfer to egg yolk

The chemical composition of free-range and conventionally-farmed eggs available to Canadians in rural Nova Scotia

In rural Nova Scotia (NS), many small family farms raise free-range hens that consume a varied diet that is different from that of conventionally-farmed hens in caged housing systems. However, it is not known how this varied diet impacts the quality of these eggs. The objective of the present study was to compare the chemical composition of free-range eggs obtained from a small family farm in rural NS to that of conventionally-farmed eggs purchased from a local grocery store. The values obtained from the present study were also compared to published values in the Canadian Nutrient File (CNF) and the U.S. Department of Agriculture FoodData Central database. The egg components and the amino acid compositions were evaluated, and protein concentrations were determined using the Kjeldahl method whereas the fatty acid profiles of the egg yolks were determined using gas chromatography. No difference (P = 0.3) in protein content was observed in free-range eggs (10.6 ± 1.1%) compared to conventionally-farmed eggs (9.7 ± 0.6%). Similar values were also observed for the physical properties of the two types of eggs measured except for the weights of the egg shells. Conversely, the amino acid cysteine, was in higher amounts (P = 0.05) 0.26 g/100 g in the CNF compared to the measured values of ~0.16 g/100 g. Notably, the polyunsaturated linoleic acid (C18:2n-6) was higher (P = 0.001) in the free-range eggs (45.6%) compared to (40.8%) the conventionally-farmed eggs. The cholesterol content of egg yolks was lower in free-range eggs (253.4 ± 0.01 mg/extra-large yolk or 14 mg cholesterol/g of yolk) vs. for conventionally-farmed eggs (263 ± 0.7 mg/extra-large yolk or 15.4 mg cholesterol/g of yolk), respectively. In terms of protein nutrition, free-range eggs may be a suitable alternative to conventionally-farmed eggs, moreover, the lower cholesterol content may be a favourable attribute for Canadian consumers who wish to purchase local free-range eggs.

Time course of nutritional and functional property changes in egg yolk from laying hens fed docosahexaenoic acid-rich microalgae

Marine microalgae (MA) has received wide attention as a promising source of omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) enrichment in animal products to improve the health status and wellbeing of the consumers. This study evaluated dynamic changes in n-3 LC-PUFA, color, and functional properties as well as atherogenic and thrombogenic health lipid indices of egg yolk from hens fed graded levels (0, 0.5, and 1.0%) of docosahexaenoic acid (DHA)–rich MA (Aurantiochytrium sp.) during a 56-D feeding period. Egg freshness parameters and yolk lipid oxidative stability were also measured after 0, 14, and 28 D of refrigerated storage. The hen performance and egg quality (except for yolk color) were not affected (P > 0.05) by MA supplementation. Docosahexaenoic acid contents in yolk from hens fed 1.0% MA increased quadratically with feeding time with a plateau at about 30 D (P < 0.05). Afterward, the DHA content leveled off to a constant value (946.3 mg/100 g yolk) with the n-6/n-3 ratio at 3.5: 1. Dietary inclusion of 1.0% of MA also significantly decreased the atherogenic and thrombogenic indices of yolk lipid (P < 0.05). Because the microalgal carotenoids incorporated into egg yolk, the L∗ value of yolk from hens fed MA decreased whereas a∗ value increased (P < 0.05), corresponding to yolk Roche color scores. As expected, there were no significant changes in yolk functional properties (e.g., viscosity and emulsifying activity) related to DHA enrichment (P > 0.05). Microalgal carotenoids enrichment also helped attenuate fatty acid oxidation of the DHA-enriched yolk and increase their lipid oxidative stability. In conclusion, dietary supplementation with up to 1.0% of MA significantly increased DHA contents with more health-promoting n-6/n-3 ratio and atherogenic and thrombogenic indices, as well as more intense yolk color within consumers' acceptability, and the feeding strategy had a minimal impact on yolk physical and functional properties or oxidative stability during subsequent refrigerated storage.

Tocopherol and annatto tocotrienols distribution in laying-hen body

The impact of supplementing laying-hen feed with annatto tocotrienols (T3s) and alpha-tocopherol on the distribution of various forms of vitamin E and cholesterol throughout the hen's body was evaluated. A total of 18 organs or tissues (skin, fat pad, liver and gall bladder, heart, oviduct, forming yolk, laid yolk, lungs, spleen, kidney, pancreas, gizzard, digestive tract, brain, thigh, breast, manure, and blood) were collected after 7 wk of feeding on diets enriched with various levels of alpha-tocopherol and annatto extract that contained gamma-T3 and delta-T3. Tissue weights, contents of lipid, alpha-tocopherol, gamma-T3, delta-T3, cholesterol, and fatty acid composition of extracted lipids from the collected organs and tissues were determined. Tissue weight and lipid content did not change significantly with feed supplementation treatments, except that the liver became heavier with increased levels of supplementation. Overall, the main organs that accumulated the supplemented vitamin E were fat pad, liver and gall bladder, oviduct, forming yolks, laid yolks, kidney, brain, thigh, and breast. Much of annatto gamma-T3 and delta-T3 (> 90%) was found in the manure, indicating poor uptake. In some tissues (brain and oviduct,) a significant increase in polyunsaturated fatty acids was seen with increased supplementation. Alpha-tocopherol impacted the transfer of gamma-T3 to forming and laid yolks, but did not impact delta-T3 transfer. No significant differences were found in most of the tissues in cholesterol, except a reduction in heart, based on tissue as-is. Blood samples showed large variations in individual hens with no significant differences in total and HDL cholesterol, or total triacylglycerols. Supplementing feed with annatto T3s and alpha-tocopherol showed that the vitamin E profile and distribution of the laying-hen body can be altered, but to different extents depending on tissue. The result of this research has significance in enhancing meat nutrient content.