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AIMS: The study aimed to evaluate the effects of dietary folic acid (FA) on the production performance of laying hens, egg quality, and the nutritional differences between eggs fortified with FA and ordinary eggs. METHODS: A total of 288 26-week-old Hy-Line Brown laying hens (initial body weights 1.65 ± 0.10 kg) with a similar weight and genetic background were used. A completely randomized design divided the birds into a control group and three treatment groups. Each group consisted of six replicates, with twelve chickens per replicate. Initially, all birds were fed a basal diet for 1 week. Subsequently, they were fed a basal diet supplemented with 0, 5, 10, or 15 mg/kg FA in a premix for a duration of 6 weeks. RESULTS: Supplementation of FA could significantly (p < 0.05) enhance the FA content in egg yolks, particularly when 10 mg/kg was used, as it had the most effective enrichment effect. Compared to the control group, the Glu content in the 10 and 15 mg/kg FA groups showed a significant (p < 0.05) decrease. Additionally, the contents of Asp, Ile, Tyr, Phe, Cys, and Met in the 15 mg/kg FA group were significantly (p < 0.05) lower compared to the other groups. Adding FA did not have significant effects on the levels of vitamin A and vitamin E in egg yolk, but the vitamin D content in the 5 and 10 mg/kg FA groups showed a significant (p < 0.05) increase. Furthermore, the addition of FA did not have a significant effect on the levels of Cu, Fe, Mn, Se, and Zn in egg yolk. The dietary FA did not have a significant effect on the total saturated fatty acids (SFA) and polyunsaturated fatty acid (PUFA) content in egg yolk. However, the total monounsaturated fatty acid (MUFA) content in the 5 and 10 mg/kg groups significantly (p < 0.05) increased. These changes in nutritional content might be attributed to the increased very low-density lipoprotein (VLDL) protein content. The significant decrease in solute carrier family 1 Member 1 (SLC1A1), solute carrier family 1 Member 2 (SLC1A2), and solute carrier family 1 Member 3 (SLC1A3) gene expression compared to the control group appeared to be the reason for the decrease in amino acid content in egg yolk within the dietary FA group. CONCLUSION: The findings suggest that the appropriate addition of FA can enhance the levels of MUFA and vitamin D in egg yolks, thereby improving their nutritional value. Excessive intake of FA can decrease the effectiveness of enriching FA in egg yolk and impact the enrichment of certain amino acids. The yolk of eggs produced by adding 10 mg/kg of FA to the feed contains the optimal amount of nutrients. This study informs consumers purchasing FA-fortified eggs.
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BACKGROUND: Shear stress caused by arteriovenous fistula (AVF) enhances endothelium-dependent relaxation (EDR) but oxidized low-density lipoprotein (ox- LDL) counteracts its effect. Probucol, a lipid soluble antioxidant, may preserve EDR of AVF by limiting oxidation of LDL. METHODS: Twenty New Zealand rabbits, fed with 2% cholesterol chow for 4 weeks, underwent AVF. They were then divided into two groups: continuing with 2% cholesterol chow alone (group I) and 2% cholesterol chow with 1% probucol supplement (group II). Another 10, fed regular chow, were assigned to the control (group III). The levels of cholesterol and LDL were measured. Segments of the AVF afferent arteries were harvested to check intimal thickness, and endothelium-dependent and independent relaxations, after 4 weeks dietary treatment had been completed. RESULTS: Both cholesterol and LDL levels were significantly elevated after 4 weeks of cholesterol feeding. These profiles reached higher levels at 8 weeks in group I and were less increased in group II. The intimal hyperplasia ratio was 48% in group I, 34% in group II and 24% in group III. Maximal EDR response to either acetylcholine or receptor-independent calcium ionophore A23187 in group II was greater than that in group I (66 +/- 1.9% versus 38 +/- 1.2%, p = 0.02; 76 +/- 2.4% versus 30 +/- 0.8%, p = 0.01) and not different from that in group III (74 +/- 2.4%, 84 +/- 3.7%). There was no similar difference of denuded arterial rings among the three groups (76 +/- 3.2%, 78 +/- 3.7%, 82 +/- 4.1%). CONCLUSION: Cholesterol can limit EDR of AVF and produce vulnerability to early occlusion and thrombosis. Probucol supplement under hyperlipidemia status preserves EDR and not endothelium-independent relaxation.