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Joachim M Weitzel, Torsten Viergutz, Dirk Albrecht, Rupert Bruckmaier, Marion Schmicke, Armin Tuchscherer, Franziska Koch and Björn Kuhla

During the transition between late gestation and early lactation, dairy cows experience severe metabolic stress due to the high energy and nutrient requirements of the fetus and the mammary gland. Additional thermal stress that occurs with rising temperatures during the ongoing climate change has further adverse implications on energy intake, metabolism and welfare. The thyroid hormone (TH)-mediated cellular signaling has a pivotal role in regulation of body temperature, energy intake and metabolic adaptation to heat. To distinguish between energy intake and heat stress-related effects, Holstein cows were first kept at thermoneutrality at 15°C followed by exposure to heat stress (HS) at 28°C or pair-feeding (PF) at 15°C for 6 days, in late pregnancy and again in early lactation. Herein, we focused on hepatic metabolic changes associated with alterations in the hypothalamic–pituitary–thyroid axis in HS and PF animals. T3 and T4 levels dropped with HS or PF; however, in HS animals, this decline was more pronounced. Thyroid-stimulating hormone (TSH) levels remain unaffected, while plasma cholesterol concentrations were lower in HS than PF animals. Hepatic marker genes for TH action (THRA, DIO1 and PPARGC1) decreased after HS and were lower compared to PF cows but only post-partum. Proteomics data revealed reduced hepatic amino acid catabolism ante-partum and a shift toward activated beta-oxidation and gluconeogenesis but declined oxidative stress defense post-partum. Thus, liver metabolism of HS and PF cows adapts differently to diminished energy intake both ante-partum and post-partum, and a different TH sensitivity is involved in the regulation of catabolic processes.

Free access

Sabina Börner, Michael Derno, Sandra Hacke, Ulrike Kautzsch, Christine Schäff, Sint ThanThan, Hideto Kuwayama, Harald M Hammon, Monika Röntgen, Rosemarie Weikard, Christa Kühn, Armin Tuchscherer and Björn Kuhla

Free access

Sabina Börner, Michael Derno, Sandra Hacke, Ulrike Kautzsch, Christine Schäff, Sint ThanThan, Hideto Kuwayama, Harald M Hammon, Monika Röntgen, Rosemarie Weikard, Christa Kühn, Armin Tuchscherer and Björn Kuhla

Ghrelin is a gastrointestinal peptide hormone that is present in blood mostly in a non-posttranslationally modified form, with a minor proportion acylated at Ser3. Both ghrelin forms were initially assigned a role in the control of food intake but there is accumulating evidence for their involvement in fat allocation and utilization. We investigated changes in the ghrelin system in dairy cows, exhibiting differences in body fat mobilization and fatty liver, from late pregnancy to early lactation. Sixteen dairy cows underwent liver biopsy and were retrospectively grouped based on high (H) or low (L) liver fat content post-partum. Both groups had a comparable feed intake in week −6 (before parturition) and week 2 (after parturition). Only before parturition was preprandial total ghrelin concentration higher in L than in H cows and only after parturition was the basal plasma concentration of non-esterified fatty acids higher in H than in L cows. Both before and after parturition, H cows had higher preprandial plasma concentrations of acyl ghrelin, a higher acyl:total ghrelin ratio, lower plasma triacylglyceride concentrations and a lower respiratory quotient compared with L cows. These group differences could not be attributed to an allelic variant of the acyl ghrelin receptor. Rather, the ratio of acyl:total ghrelin correlated with several aspects of fat metabolism and with respiratory quotient but not with feed intake. These results show that endogenous ghrelin forms are associated with fat allocation, fatty liver, and utilization of fat during the periparturient period.