Zhang Menglu, Liu Zhentao, Wu Kuixian, Zhang Chuankai, Fu Tong, Sun Yu, Gao Tengyun, Han Liqiang
Henan International Joint Laboratory of Nutrition Regulation and Ecological Raising of Domestic Animal, College of Animal Science and Technology, Henan Agricultural University, Zhengzhou 450046, China.
Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs, College of Verterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China.
Animals (Basel). 2024 Sep 9;14(17):2614. doi: 10.3390/ani14172614.
The aim of this study was to evaluate the effect of conjugated linoleic acid (CLA) on milk fat globule (MFG) size and the ruminal microbiome of goats. Twenty-four mid-lactation Saanen dairy goats weighing 49 ± 4.5 kg (168 ± 27 d in milk, 1.2 ± 0.1 kg milk/d, 2-3 years old) were randomly divided into four groups-a control (CON) group, which was fed a basal diet, and three CLA supplementation groups, in which 30 g CLA (low-dose group, L-CLA), 60 g CLA (medium-dose group, M-CLA), or 90 g CLA (high-dose group, H-CLA) was added to the basal diet daily. The experiment lasted for 21 days, during which time goat milk was collected for composition and MFG size analysis. On day 21 of feeding, ruminal fluid was collected from the CON and H-CLA groups for analysis of the changes in microorganismal abundance. The results showed that CLA supplementation did not affect milk production, milk protein, or lactose content in the dairy goats ( > 0.05), but significantly reduced the milk fat content ( < 0.01) compared with the CON group. The CLA supplementation significantly decreased the D and D of the MFGs in a dose-dependent manner ( < 0.01). Moreover, dietary CLA inclusion increased the proportion of small-sized MFGs and decreased that of large-sized ones. The results of 16S rRNA gene sequencing showed that CLA-induced milk fat depression in dairy goats was accompanied by significant changes in the relative abundance of ruminal bacterial populations, most of which belonged to the Firmicutes and Bacteroidetes phyla. The relative abundance of and in Bacteroidetes and , , and norank_f__norank_o__group in Firmicutes was significantly higher in the CON group than in the H-CLA group. In contrast, the relative abundance of norank_f__, norank_f__group, unclassified_f__, and in Firmicutes and norank_f__ in Bacteroidetes was significantly higher in the H-CLA group than in the CON group. Correlation analysis showed that the milk fat content was negatively correlated with the relative abundance of some bacteria, including members of Firmicutes and Bacteroidetes. Similarly, MFG size (D and D) was negatively correlated with several members of Firmicutes and Bacteroidetes, including , norank_f__, , norank_f___group (Firmicutes), and norank_f__ (Bacteroidetes), while positively correlated with the relative abundance of some members of Firmicutes and Bacteroidetes, including , , norank_f__norank_o__group, (Firmicutes), and group (Bacteroidetes). Overall, our data indicated that CLA treatment affected milk fat content and MFG size in dairy goats, and these effects were correlated with the relative abundance of ruminal bacterial populations. These results provide the first evidence to explain the mechanism underlying diet-induced MFG from the perspective of the ruminal microbiome in dairy goats.
本研究的目的是评估共轭亚油酸（CLA）对奶山羊乳脂肪球（MFG）大小和瘤胃微生物群的影响。24只处于泌乳中期的萨能奶山羊，体重49±4.5千克（产奶168±27天，日产奶1.2±0.1千克，2 - 3岁），被随机分为四组——对照组（CON），饲喂基础日粮；三个CLA补充组，分别在基础日粮中每日添加30克CLA（低剂量组，L - CLA）、60克CLA（中剂量组，M - CLA）或90克CLA（高剂量组，H - CLA）。实验持续21天，在此期间收集山羊奶进行成分和MFG大小分析。在饲喂第21天，从CON组和H - CLA组收集瘤胃液，用于分析微生物丰度的变化。结果表明，补充CLA对奶山羊的产奶量、乳蛋白或乳糖含量没有影响（P>0.05），但与CON组相比，显著降低了乳脂肪含量（P<0.01）。补充CLA以剂量依赖的方式显著降低了MFG的D和D（P<0.01）。此外，日粮中添加CLA增加了小尺寸MFG的比例，降低了大尺寸MFG的比例。16S rRNA基因测序结果表明，CLA诱导奶山羊乳脂肪降低伴随着瘤胃细菌种群相对丰度的显著变化，其中大多数属于厚壁菌门和拟杆菌门。拟杆菌门中的 和 以及厚壁菌门中的 、 和norank_f__norank_o__group在CON组中的相对丰度显著高于H - CLA组。相反，厚壁菌门中的norank_f__、norank_f__group、unclassified_f__和 以及拟杆菌门中的norank_f__在H - CLA组中的相对丰度显著高于CON组。相关性分析表明，乳脂肪含量与一些细菌的相对丰度呈负相关，包括厚壁菌门和拟杆菌门的成员。同样，MFG大小（D和D）与厚壁菌门和拟杆菌门的几个成员呈负相关，包括 、norank_f__、 、norank_f___group（厚壁菌门）和norank_f__（拟杆菌门），而与厚壁菌门和拟杆菌门的一些成员的相对丰度呈正相关，包括 、 、norank_f__norank_o__group、 （厚壁菌门）和group（拟杆菌门）。总体而言，我们的数据表明CLA处理影响了奶山羊的乳脂肪含量和MFG大小，并且这些影响与瘤胃细菌种群的相对丰度相关。这些结果提供了首个证据，从奶山羊瘤胃微生物群的角度解释了日粮诱导MFG的潜在机制。
