This study assessed the effects of different levels of milk thistle (Silybum marianum) meal (MTM) on egg quality traits, oxidative stability, blood biochemical parameters and liver health indices in laying hens receiving diets supplemented with lipid from different sources. For this purpose, Leghorn laying hens (Hy-Line W-36) were randomly assigned to 12 experimental treatments with eight replicates of five birds each. Dietary treatments consisted of four dietary fat sources (fish oil, sunflower oil, poultry oil and fat powder, each with different fatty acid profiles) and three levels of MTM (0.0, 15 and 30 g/kg) offered through 10 days of adaptation and 70 days of main recording. Results showed that dietary inclusion of polyunsaturated fatty acids, including fish or sunflower oils, reduced serum cholesterol content but increased blood malondialdehyde (MDA) concentration (p < 0.05). While fish oil improved the yolk colour index and Haugh unit (p < 0.05), it decreased yolk cholesterol concentration (p < 0.01). The highest hepatic glycogen content and tissue integrity as well as the lowest liver lipid percentage and MDA content were observed in birds fed diets supplemented with poultry oil. On the other hand, feeding 30 g/kg of MTM reduced not only hepatic lipid percentage but also aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities (p < 0.01), while it improved eggshell strength and thickness (p < 0.05). Supplementation of fat powder enhanced hepatic C16:0 content, while addition of poultry, sunflower or fish oil increased C18:1, C18:2 or C20:5 concentrations respectively (p < 0.01); nonetheless, feeding the highest level of MTM reduced hepatic ΣSFA but increased Σn-3 fatty acids (p < 0.01). The interaction effects indicated that fish or sunflower oil supplementation increased the MTM level required to reduce not only serum or egg cholesterol concentrations (p < 0.05) but also blood or hepatic MDA content (p < 0.01). It was concluded that fish oil and MTM (30 g/kg) supplements might improve internal egg quality traits and eggshell quality respectively. The hepatic fatty acid profile was also found strongly correlated with dietary fatty acids. Finally, the best hepatic health indices and the highest oxidative stability were achieved when the birds were fed diets supplemented with poultry oil and 30 g/kg of MTM.

中文翻译：

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通过补充替代脂质源和水飞蓟粉可改善肝脂肪酸谱、氧化稳定性和鸡蛋质量特性


本研究评估了不同水平的水飞蓟 ( Silybum marianum ) 粉 (MTM) 对饲喂不同来源脂质的蛋鸡的蛋品质性状、氧化稳定性、血液生化参数和肝脏健康指数的影响。为此，来航蛋鸡 (Hy-Line W-36) 被随机分配到 12 个实验处理组，每个处理组有 8 个重复组，每组 5 只鸡。饮食治疗包括四种膳食脂肪来源（鱼油、葵花籽油、家禽油和脂肪粉，每种都有不同的脂肪酸谱）和三个水平的 MTM（0.0、15 和 30 g/kg），经过 10 天的适应和治疗70天的主要录音。结果表明，饮食中添加多不饱和脂肪酸（包括鱼油或葵花籽油）可降低血清胆固醇含量，但增加血液丙二醛 (MDA) 浓度 ( p < 0.05)。虽然鱼油改善了蛋黄颜色指数和哈夫单位 ( p < 0.05)，但它降低了蛋黄胆固醇浓度 ( p < 0.01)。在添加家禽油的饲料中观察到最高的肝糖原含量和组织完整性以及最低的肝脏脂质百分比和丙二醛含量。另一方面，饲喂 30 g/kg 的 MTM 不仅降低了肝脂质百分比，还降低了天冬氨酸转氨酶 (AST) 和丙氨酸转氨酶 (ALT) 活性 ( p < 0.01)，同时提高了蛋壳强度和厚度 ( p < 0.05) 。补充脂肪粉可提高肝脏 C16:0 含量，而添加家禽油、葵花籽油或鱼油则分别提高 C18:1、C18:2 或 C20:5 浓度（ p < 0.01);尽管如此，饲喂最高水平的 MTM 会降低肝脏 ΣSFA，但会增加 Σn-3 脂肪酸 ( p < 0.01)。相互作用效应表明，补充鱼油或葵花籽油不仅提高了降低血清或鸡蛋胆固醇浓度 ( p < 0.05) 所需的 MTM 水平，还提高了降低血液或肝脏 MDA 含量 ( p < 0.01) 所需的 MTM 水平。结论是鱼油和 MTM (30 g/kg) 补充剂可能分别改善鸡蛋内部质量特性和蛋壳质量。还发现肝脏脂肪酸谱与膳食脂肪酸密切相关。最后，当家禽饲喂添加禽油和 30 g/kg MTM 的日粮时，获得了最佳的肝脏健康指数和最高的氧化稳定性。