Short communication: Adipocyte sizes in the digital fat pad and their relationship to body condition in dairy cows

Abstract

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.

Morphology, adipocyte size, and fatty acid analysis of dairy cattle digital cushions, and the effect of body condition score and age

“…This study found that adipocyte cell size was significantly larger in animals with a higher BCS. This is consistent with a previous study that investigated adipocyte size in bovine right front claws in cows with a BCS of less than 3.00, and 3.00 or more, on a 1 to 5 scale (Hiss-Pesch et al, 2019), a study which also supports our assertion that the digital cushion is not a homogeneous tissue. Interestingly, the average adipocyte cell size in the current study (between 373 and B) Body condition score grouped into scores of 1.50 to 2.50 (n = 8) and 3.00 to 4.00 (n = 7; P > 0.05 independent samples t-test).…”

“…(C) Age grouped into 2 to <4 yr (n = 5) and ≥4 to 6.5 yr (n = 12; P > 0.05 independent samples t-test). 6248 759 µm 2 for each individual animal), was smaller in comparison to other publications on bovine species, where digital cushion adipocyte averages were between 1,426 and 5,692 µm 2 depending on the breed, location of the sample, and factors such as BCS (Hiss-Pesch et al, 2019). Adipocytes in subcutaneous and retroperitoneal adipose tissues reached around 7,000 and 8,000 µm 2 (Kénéz et al, 2015), whereas another study showed that subcutaneous and visceral depots had adipocyte cell areas ranging from 4,521 to 7,945 µm 2 (Akter et al, 2011).…”

A Prospective Cohort Study on the Development of Claw Horn Disruption Lesions in Dairy Cattle; Furthering our Understanding of the Role of the Digital Cushion

“…The inconsistency regarding when in lactation the SSTT nadir occurs between our study and the Newsome et al ( 17 ) study could be due to the difference in the fat pad targeted. A recent short communication by Hiss-Pesch et al ( 25 ) reported that the fat pads within the digital cushion are not uniform and that fat could be mobilized from them at different rates. It could also be due to different farm management systems or differences in genetics.…”

Genetic parameters and genome-wide association study of digital cushion thickness in Holstein cows

“…The KCNQ3 gene has previously been associated with milk fat percentage and milk yield in Holsteins (Kolbehdari et al, 2008;Jiang et al, 2019), while EFR3A has previously been associated with subclinical ketosis, milk fat percentage, and milk fatty acid composition in Holsteins (Li et al, 2014;Jiang et al, 2019;Soares et al, 2021). The lipid composition of the digital cushion changes with age (Räber et al, 2006) and is correlated with body condition (Hiss-Pesch et al, 2019;Newsome et al, 2021). Although it is not clear how the composition of the digital cushion affects its physical properties, it is plausible that the same genes that affect the fat and fatty acid content of milk could similarly influence the digital cushion.…”