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To ascertain an appropriate level of isoleucine for LSL-LITE layers (23- to 30-week-old), diets containing total isoleucine concentrations (levels) of 0.66 (Control), 0.69, 0.72, 0.75, 0.78, 0.81, and 0.84% were fed as 7 treatments (2730 kcal/kg metabolizable energy) x 7 replicates x 10 birds per replicate. Significance for performance, egg quality, serum biochemistry, and ileal digestibility of protein was determined at P ≤ 0.05. Level, week, and level*week (L*W) were significant for production, egg mass, and feed intake. Level and week were significant for FCR. Week was significant for weight gain. Level was significant for egg weight, specific gravity, and shell thickness; week was also significant for these external egg parameters as well as shape index and proportional shell thickness. L*W was significant for all except shape index. For internal egg measurements, level was significant for proportional yolk, proportional albumen, yolk index, and yolk:albumen. Week was significant for internal egg parameters while L*W significantly affected Haugh unit, proportional albumen weight, yolk index, albumen index, and yolk color. Level was significant for globulin and glucose in serum. Isoleucine at 0.72%, 0.81%, and 0.84% produced the lowest FCR, an important standard in the poultry industry. Considering the low FCR of 1.45 and cost for inclusion as a dietary ingredient, 0.72% isoleucine was chosen for further studies with varying quantities of other branched chain amino acids in diets for young laying hens., Competing Interests: I have read the journal’s policy and the authors of this manuscript have no competing interests.

The sensory attributes and consumer acceptance of eggs from flax seed-fed hens were evaluated by trained and untrained panelists. Hens were fed diets containing 0% flax seed (control), 10% flax seed (flax), 10% flax seed+100 IU/kg of vitamin E (flax+α-tocopherol), or 10% flax seed+100 mg/kg of butylated hydroxytoluene (BHT) (flax+BHT). Fresh eggs collected within 24 h were hard-boiled, coded, and were offered to trained panelists in 4 testing sessions. Sensory traits evaluated were aroma, flavor, off-flavor, and overall difference. The trained panelists rated flax, flax+α-tocopherol, and flax+BHT eggs to be different from control eggs (P<0.001). In a second study, sensory attributes were tested by untrained panelists. The majority (75 to 80%) of the panelists could not distinguish flax seed-fed versus control eggs for aroma and flavor. A consumer preference test was also conducted to gauge end-user response to flax seed-fed eggs. Consumer acceptance testing did not find any significant difference (P>0.05) between control and flax seed-fed eggs. These results suggest that flax seed when incorporated at 10% in the layer diet can produce eggs that are acceptable to untrained panelists and consumers. However, trained panelists are able to detect differences in flavor, aroma, and off-flavor and overall difference in eggs from hens fed flax seed. Antioxidant supplementation (vitamin E, BHT) did not enhance the acceptability of flax seed-fed eggs by trained panelists.

An experiment was conducted to investigate the effect of dietary antioxidants and storage on fatty acid profile, oxidative stability, and vitamin E concentration of n-3 fatty acid-enriched eggs. Eggs (384, 48/diet) were collected from ISA Brown layers fed diets containing corn-soy (control) with 100 g/kg of flax seed and 2 types of antioxidants [alpha-tocopherols (alpha-TOC) and butylated hydroxytoluene (BHT)] at 0, 50, 100, or 150 IU or mg/kg. Eggs were stored at 4 degrees C. On d 0, 20, 40, and 60 of storage, 2 eggs were selected randomly from each replicate (totaling 12 eggs per treatment) and analyzed. Eggs from hens fed flax had increased alpha-linolenic (18:3n-3), eicosapentaenoic (20:5n-3), and docosahexaenoic acids (DHA, 22:6n-3) and decreased arachidonic acid (20:4n-6) and total n-6:n-3 ratio when compared with control eggs (P<0.05). The n-6:n-3 fatty acid ratio was lowest in the flax+50 IU of alpha-TOC, flax+100 IU of alpha-TOC, and flax+BHT supplemented group when compared with the flax group (P<0.05). With the exception of flax+100 mg of BHT, addition of antioxidants led to a reduction in palmitic acid in fresh eggs (P<0.05). During the first 20 d of storage, over a 17% reduction in total n-3 fatty acids was observed in eggs from flax+50 mg of BHT supplemented groups (P<0.05). Docosahexaenoic acid was the predominant long-chain n-3 fatty acid in egg and was stable during storage in the control, flax, flax+100 IU of alpha-TOC, flax+150 IU of alpha-TOC, and flax+150 mg of BHT groups. However, antioxidant supplementation had no effect on DHA upon storage in flax+50 IU of alpha-TOC and flax+50 mg of BHT eggs where over 13 to 17% reduction in DHA content was observed during 20 to 60 d of storage (P<0.05). Inclusion of alpha-TOC led to over 4.5- to 12-fold increases in alpha-TOC in eggs. Egg storage for 40 d or longer led to over 50% reduction in egg alpha-TOC (P<0.05). Feeding flax seeds led to an increase in TBA reactive substances in eggs (P<0.05). alpha-Tocopherol was better in preventing lipid oxidation than BHT at d 0 of storage. However, neither had a significant effect on egg TBA reactive substances upon 60 d of storage (P>0.05). These studies demonstrate that the level and type of antioxidants and duration of egg storage significantly affected the fatty acid profile, alpha-TOC status, and oxidative stability of chicken eggs.