Laurent C, Caillat H, Girard C L, Ferlay A, Laverroux S, Jost J, Graulet B
Université Clermont Auvergne, INRAE, VetAgro Sup, UMR Herbivores, F-63122 Saint-Genès-Champanelle, France.
FERLus, INRAE, Les Verrines, 86600 Lusignan, France.
Animal. 2023 Jan;17(1):100683. doi: 10.1016/j.animal.2022.100683. Epub 2022 Nov 21.
The content, composition and variation of vitamin compounds in goat milk have been little studied. An experimental design was based on 28 commercial farms, selected considering the main feeding system (based on main forage and especially pasture access), goat breed (Alpine vs Saanen) and reproductive management (seasonal reproduction), in the main French goat milk production area. Each farm received two visits (spring and autumn) that included a survey on milk production conditions and bulk milk sampling. Milk vitamins (A, E, B, B, B, B) and carotenoid concentrations plus colour indices were evaluated. A stepwise approach determined the variables of milk production conditions that significantly altered milk indicators. The main forage in the diet was the major factor altering goat milk vitamin and carotenoid concentrations and colour indices. Bulk milk from goats eating fresh grass as forage was richer in α-tocopherol (+64%), pyridoxal (+35%) and total vitamin B (+31%), and b* index (characterising milk yellowness in the CIELAB colour space) was also higher (+12%) than in milk from goats eating conserved forages. In milk from goats eating fresh grass, concentrations of pyridoxamine, lutein and total carotenoids were higher than in milk of goats fed corn silage (+24, +118 and +101%, respectively), and retinol and α-tocopherol concentrations were higher than in milk of goats fed partially dehydrated grass (+45 and +55%). Vitamin B concentration was higher in milk of goats eating fresh grass than in milk of goats fed hay or corn silage as forage (+10%). However, bulk milk when goats had access to fresh grass was significantly poorer in vitamin B than when fed corn silage (-46%) and in γ-tocopherol (-31%) than when fed conserved forage. Alpine goats produced milk with higher vitamin B and folate concentrations than Saanen goats (+18 and +14%, respectively). Additionally, the milk colour index that discriminates milks based on their yellow pigment contents was 7% higher in milk from Alpine than Saanen herds, but milk from Saanen goats was richer in lutein (+46%). Goat milks were richer in vitamins B and B and folates, but poorer in vitamin B in autumn than in spring (+12, +133, +15 and -13%, respectively). This work highlights that goat milk vitamin and carotenoid concentrations and colour indices vary mainly according to the main forage of the diet and secondly according to the breed and season.
山羊奶中维生素化合物的含量、组成及变化情况鲜少有人研究。在法国主要的山羊奶生产区，基于28个商业农场进行了一项实验设计，选择这些农场时考虑了主要饲养系统（基于主要饲料尤其是牧场可及性）、山羊品种（阿尔卑斯山羊与萨能山羊）以及繁殖管理（季节性繁殖）。每个农场接受两次走访（春季和秋季），走访内容包括对牛奶生产条件的调查以及采集散装牛奶样本。对牛奶中的维生素（A、E、B₁、B₂、B₆、B₁₂）、类胡萝卜素浓度以及颜色指数进行了评估。采用逐步分析方法确定了显著改变牛奶指标的牛奶生产条件变量。日粮中的主要饲料是改变山羊奶维生素、类胡萝卜素浓度及颜色指数的主要因素。以鲜草为饲料的山羊所产散装牛奶中，α - 生育酚含量更高（+64%）、吡哆醛含量更高（+35%）、总维生素B含量更高（+31%），并且b*指数（在CIELAB颜色空间中表征牛奶黄色程度）也比以青贮饲料为食的山羊所产牛奶更高（+12%）。在以鲜草为食的山羊所产牛奶中，吡哆胺、叶黄素和总类胡萝卜素的浓度高于以玉米青贮饲料为食的山羊所产牛奶（分别高出+24%、+118%和+101%），视黄醇和α - 生育酚浓度高于以半干牧草为食的山羊所产牛奶（分别高出+45%和+55%）。以鲜草为食的山羊所产牛奶中维生素B₆的浓度高于以干草或玉米青贮饲料为食的山羊所产牛奶（高出+10%）。然而，山羊能够吃到鲜草时所产的散装牛奶中，维生素B₁₂含量比以玉米青贮饲料为食时显著更低（-46%），γ - 生育酚含量比以青贮饲料为食时更低（-31%）。阿尔卑斯山羊所产牛奶中维生素B₆和叶酸浓度高于萨能山羊（分别高出+18%和+14%）。此外，基于黄色色素含量区分牛奶的颜色指数在阿尔卑斯山羊群所产牛奶中比在萨能山羊群所产牛奶中高7%，但萨能山羊所产牛奶中叶黄素含量更丰富（+46%）。山羊奶中维生素B₁、B₂和叶酸含量更丰富，但秋季的山羊奶中维生素B₁₂含量比春季更低（分别为+12%、+133%、+15%和-13%）。这项研究突出表明，山羊奶中维生素和类胡萝卜素浓度以及颜色指数的变化主要取决于日粮中的主要饲料，其次取决于品种和季节。
