Influence of Age and Breed on Bovine Ovarian Capillary Blood Supply, Ovarian Mitochondria and Telomere Length

Paweł Kordowitzki,Pascal-Kolja Hass,Roswitha Merle,Johanna Plendl,Juliane Rieger,Sabine Kaessmeyer

doi:10.3390/cells10102661

Abstract

Worldwide, dairy cows of the type of high-producing cattle (HPC) suffer from health and fertility problems at a young age and therefore lose productivity after an average of only three lactations. It is still contentious whether these problems are primarily due to genetics, management, feeding or other factors. Vascularization plays a fundamental role in the cyclic processes of reproductive organs, as well as in the regeneration of tissues. In a previous study, HPC were shown to have a greater ovarian corpus luteum vascularization compared to dual-purpose breeds. We hypothesize that this activated angiogenesis could likely lead to an early exhaustion of HPC′s regenerative capacity and thus to premature reproductive senescence. The objective of this study was to investigate if a HPC breed (Holstein-Friesian, HF) exhibits higher ovarian angiogenesis than a dual-purpose breed (Polish Red cow, PR) and if this is related to early ovarian aging and finally reproductive failure. For this purpose, we assessed the degree of vascularization by means of ovarian blood vessel characterization using light microscopy. As indicators for aging, we measured ovarian mitochondrial size and telomere length in peripheral leukocytes. We report in this study that in both breeds the distance between capillaries became smaller with increasing age and that the mean telomere length decreased with increasing age. The only difference between the two breeds was that PR developed larger capillaries than HF. Neither a relationship between telomere length, nor the morphology of the mitochondrial apparatus and nor angiogenesis in HF was proven. Although the data trends indicated that the proportion of shortened telomeres in HF was higher than in the PR, no significant difference between the two breeds was detected.

Highlights

The development of various phenotypic and genetic analytical approaches within the past decades has extensively contributed to our current understanding of cattle reproduction
This longtime activated angiogenesis could likely lead to an early exhaustion of high-producing cattle (HPC) s regenerative capacity, eventually leading to decreased vascularization and to premature senescence, after a short lifespan characterized by constant, maximal performance that takes its toll on the body
The objective of this study was to investigate whether there is a relationship between telomere length, the morphology of the mitochondrial apparatus and angiogenesis in HPC and whether there is a difference between HPC (Holstein-Friesians, HF) and a robust dual-purpose breed (Polish Red cow, PR)

Summary

Introduction

The development of various phenotypic and genetic analytical approaches within the past decades has extensively contributed to our current understanding of cattle reproduction. It has been hypothesized that high-producing dairy cows, with a severe negative energy balance in the early post-partum period, suffer more often from health and fertility problems at a younger age than other breeds or domesticated animals [4,5]. It is still contentious whether this is mainly due to genetics, management, feeding or other factors. In most human somatic cell types, telomeres shorten with each cell cycle due to the absence of telomerase and the end replication problem [17]

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