Short communication: Telomere lengths in different tissues of dairy cows during early and late lactation

Abstract

Telomeres create a protective cap on the ends of chromosomes that shorten with cell division and are influenced by stressful conditions. With the onset of lactation, high-yielding dairy cows are exposed to metabolic stress. In the present study, we aimed to analyze telomere length (TL) in key metabolic organs, such as liver, subcutaneous (sc) adipose tissue (AT), and mammary gland, as well as in peripheral blood cells during early and late lactation in German Holstein cows (n=21). Animals were fed according to their requirement, and biopsies from scAT, liver, and mammary gland as well as blood cells were collected in early and late lactation. The relative quantity of telomere products (qT), which is proportional to the average TL, was determined in genomic DNA by multiplex quantitative PCR. In this study, relative qT varied widely in the investigated tissues and blood. In late lactation, slowly proliferating tissues, such as liver and scAT, had the highest qT, whereas peripheral blood cells and in the mammary gland had the lowest qT. Comparing early with late lactation, relative qT attrition was limited to blood and mammary gland. Relationships between relative qT in blood, mammary gland, scAT, and liver suggest that blood qT might serve as a surrogate marker for tissue-specific qT. Cows with high initial qT in tissues and blood in early lactation had greater qT attrition during the course of lactation than cows with lower qT. The determination of qT could be included when phenotyping dairy cattle to test for associations with performance and fitness traits.

Method Specific Calibration Corrects for DNA Extraction Method Effects on Relative Telomere Length Measurements by Quantitative PCR

“…This study adds to the emerging literature showing that DNA extraction methods may affect the mean RTL measurement produced by qPCR techniques. We present the first evidence for such effects in non-human vertebrates, documenting similar results in two ruminant species of considerable economic and agricultural importance in which TL variation has recently been examined with some exciting initial results [ 28 – 30 ]. We also show that RTL measurements derived from different DNA extraction methods are highly correlated when rigorous DNA quality control is applied.…”

Correlation in telomere lengths between feathers and blood cells in pied flycatchers

“…Despite signs of moderate DNA degradation in feather samples, we found that telomere length measured from feather samples is significantly positively correlated with telomere length measured in blood cells, thereby suggesting that such relationship is robust. Relationship in telomere length across various tissues has been well characterised in humans and other mammals (Okuda et al 2002, Takubo et al 2002, Benetos et al 2011, Daniali et al 2013, Laubenthal et al 2016, but only to a lesser extent in birds (Reichert et al 2013, Schmidt et al 2016, Parolini et al 2019. Previous studies in birds have investigated telomere correlation between erythrocytes, bone marrow, spleen, muscle, heart, liver and brain in adult zebra finches (Reichert et al 2013), blood, heart and liver in embryonic and juvenile Franklins' gulls, Leucophaeus pipixcan (Schmidt et al 2016) and heart, pectoral muscle, liver and brain in embryonic yellow-legged gulls, Larus michahellis (Parolini et al 2019).…”

“…However, there is currently no information on whether telomere length measured from feather derived DNA provides similar results than blood derived DNA. Previous studies in mammals have shown correlation in telomere length among DNA samples from blood cells and different tissues (Okuda et al 2002, Takubo et al 2002, Benetos et al 2011, Daniali et al 2013, Laubenthal et al 2016. In non-model vertebrates, one study in zebra finch Taeniopygia guttata and one in painted dragon Ctenophorus pictus showed that telomere length from blood cells significantly correlates with telomere length in some tissues, but not all (Reichert et al 2013, Rollings et al 2019, but see Parolini et al 2019 for lack of relationship between different somatic tissues excluding blood).…”

Longitudinal changes in telomere length and associated genetic parameters in dairy cattle analysed using random regression models

“…Not much is known about telomere length and its association with productive lifespan in cattle so far. In cross-sectional studies bovine telomere length declines with age and during the lactation period [ 35 , 69 , 70 ]. A single study found that animals with shorter telomeres were more likely to be culled within the next year [ 35 ].…”