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In dairy cows, reproductive diseases such as cystic ovarian disease (COD) represent a major problem that impacts on dairy production. It has been postulated that the insulin-like growth factor (IGF) system may contribute to follicular persistence and development of COD. Thus, the aim of the present study was to analyze relevant members of the IGF system in a critical period immediately after the expected time of ovulation, to obtain information about their role in follicular persistence in dairy cows. Proteins of the IGF system were evaluated at 0 (expected day of ovulation), 5, 10 and 15 days of follicular persistence to determine whether the changes previously detected in cows with COD occur early in COD pathogenesis. The serum concentration of IGF1 was higher in cows with 10 and 15 days of follicular persistence than in control cows. IGF1 expression in granulosa cells was similar in the follicles analyzed. In contrast, in theca cells, persistent follicles of days 5 and 10 showed the lowest IGF1 expression. IGF binding protein (IGFBP) 2 and 3 expression was lower in persistent follicles than in dominant follicles of the control group. Although IGF receptor (IGFR) 1 expression was similar in the groups analyzed, p-IGFR1 expression was significantly higher in dominant follicles of the control group than in persistent follicles. These data suggest alterations in the IGF system at the early stages of follicular persistence. The evidences obtained allow supporting that the IGF system could plays a key role in dairy cattle reproduction., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

We aimed to study the protein and gene expression of some hepatic enzymes of lipid metabolism along with plasma biomarkers in grazing dairy cattle during the transition period. Blood and liver biopsies from a group of eight multiparous cows were sampled at -28, -14, +4, +14, +28 and +56 days relative to parturition. Peak concentrations of NEFA and beta-hydroxybutyric acid with high triacylglycerol content in the liver were recorded on day 4 postpartum. Consistent with blood biomarkers, the gene expression of carnitine palmitoyltransferase 1A (CPT1A) and acyl-CoA oxidase 1 (ACOX1) increased, whereas that of diacylglycerol O-acyltransferase 1 (DGAT1) decreased. Nevertheless, CPT1A protein expression did not change during all the period evaluated and ACOX1 protein expression increased on day 56 postpartum. In addition, the protein expression of peroxisome proliferator-activated receptor alpha (PPAR-alpha) increased on day 28 postpartum. On the other hand, DGAT1 protein expression decreased on day 14 postpartum. As expected, the expression of genes associated with fatty acid oxidation increased on the first days postpartum but, notably, protein expression was highest after transition. Since most infectious diseases and metabolic disorders in dairy cattle occur particularly on the first days postpartum, it is not so clear whether an increase in the oxidation capacity of the liver at that time could help to prevent disease and improve dairy production. The valuable results about protein expression of enzymes involved in liver lipid metabolism could help to better characterize the metabolism of dairy cattle during the transition period., (Copyright © 2019 Elsevier Ltd. All rights reserved.)