Institute of Animal Science, Physiology and Hygiene Unit, University of Bonn, 53113 Bonn, Germany.
Institute of Animal Science, Physiology and Hygiene Unit, University of Bonn, 53113 Bonn, Germany.
J Dairy Sci. 2019 Jul;102(7):6551-6554. doi: 10.3168/jds.2018-15531. Epub 2019 May 2.
Lameness and body condition are closely related. Recent studies have shown that cows with low body condition score (BCS) have a greater risk for developing lameness than cows with higher BCS. Among other reasons, this relationship might be related to the reduced thickness of the digital fat cushion in lean cows. The digital cushion is not a homogeneous structure but consists of different fat pads and connective tissue. We hypothesized that either high or low BCS will result in concordant adipocyte sizes in the fat pads of the digital cushion and subcutaneous tailhead fat irrespective of the localization of the latter. Right front claws were collected from 18 Holstein Friesian cows. Cows were selected according to their BCS: 9 cows with BCS <3 (low BCS) and 9 cows with BCS ≥3 (high BCS). After dissecting the horn capsule of the lateral claw, samples of the axial and abaxial fat pads were prepared for histomorphological examinations (adipocyte size measurement) and protein abundance of vascular endothelial growth factor A (VEGF-A) via Western blotting. In addition, fat samples were excised from the tailhead of all cows and used for the same purposes. Adipocyte size in tailhead fat was greater in high-BCS than in low-BCS cows. Similar differences between the BCS groups were apparent for adipocytes from the axial fat pad, although adipocytes in tailhead fat were larger than those in the digital cushion. In contrast to that in the axial fat pad and tailhead fat, adipocyte size in the abaxial fat pad was similar in cows from both BCS groups. A relationship between adipocyte size and VEGF-A protein was only confirmed for the axial fat pad, not for the other fat depots. When comparing BCS groups, differences in VEGF-A protein abundance between high-BCS and low-BCS cows were also limited to the axial fat pad, being absent in tailhead fat and the abaxial fat pad. Taken together, our results show that the fat pads from the digital cushion should not be considered uniform adipose tissue locations but rather discrete units reacting differently to fat mobilization.
跛行和体况密切相关。最近的研究表明，体况评分（BCS）较低的奶牛比体况评分较高的奶牛发生跛行的风险更大。除其他原因外，这种关系可能与瘦牛的数字脂肪垫厚度降低有关。数字垫不是均质结构，而是由不同的脂肪垫和结缔组织组成。我们假设，无论后者的定位如何，高或低的 BCS 都会导致数字垫脂肪垫和皮下尾头脂肪的脂肪细胞大小一致。从 18 头荷斯坦弗里生奶牛采集右前爪。根据 BCS 选择奶牛：9 头 BCS<3（低 BCS）和 9 头 BCS≥3（高 BCS）。在解剖侧爪的角胶囊后，准备轴向和背侧脂肪垫的样本进行组织形态学检查（脂肪细胞大小测量）和通过 Western blot 检测血管内皮生长因子 A（VEGF-A）的蛋白丰度。此外，从所有奶牛的尾头切除脂肪样本，并用于相同目的。高 BCS 奶牛的尾头脂肪细胞大小大于低 BCS 奶牛。虽然尾头脂肪的脂肪细胞比数字垫的脂肪细胞大，但在轴向脂肪垫中，BCS 组之间也存在类似的差异。与轴向脂肪垫和尾头脂肪不同，背侧脂肪垫的脂肪细胞大小在两个 BCS 组的奶牛中相似。仅在轴向脂肪垫中证实了脂肪细胞大小与 VEGF-A 蛋白之间存在关系，而在其他脂肪组织中则没有。在比较 BCS 组时，高 BCS 和低 BCS 奶牛之间 VEGF-A 蛋白丰度的差异也仅限于轴向脂肪垫，在尾头脂肪和背侧脂肪垫中不存在。综上所述，我们的结果表明，数字垫的脂肪垫不应被视为均质的脂肪组织位置，而应是对脂肪动员反应不同的离散单元。
