The impact of the chromium supplementation on insulin signalling pathway in different tissues and milk yield in dairy cows
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Jovanović, Ljubomir J.
Article (Published version)
© 2017 Blackwell Verlag GmbH
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Thirty days before expected time of parturition, 20 Holstein cows were divided into −Cr and +Cr groups. From day 25 before parturition (BP) up to day 30 after parturition (AP), +Cr cows received 10 mg of Cr (chromium-enriched yeast) daily. Muscle and adipose tissue samples were taken at days −30, −10, +7 and +10 related to parturition, when body condition score (BCS) was also determined. Hepatic tissue samples were taken at days −10 and +7. Tissue samples were used for determination of the insulin signalling pathway protein expressions. Intravenous glucose tolerance test (IVGTT) was performed at days −28, −7, +10 and +30. Milk yield was recorded during first 14 weeks AP. Milk composition was obtained at days 7 and 28 AP. At day 10 BP, protein content of β-subunit of insulin receptor (IRβ) was significantly higher (p ˂ 0.05) in muscle, and phosphorylation of insulin receptor substrate 1 at serine 307 (pIRS-1 Ser307) was significantly lower (p ˂ 0.05) in hepatic tissue of +Cr group. Afte...r parturition, pIRS-1 Ser307 was significantly lower in muscle tissue at days 7 and 28 (p ˂ 0.05 and p ˂ 0.001, respectively), while phosphorylation of Akt at serine 473 (pAkt Ser473) was significantly higher (p ˂ 0.01) in hepatic tissue at day 7 AP in +Cr group. Chromium had opposite effect on insulin kinetics during IVGTTs obtained BP and AP. Insulin secretion was significantly reduced at day 7 BP and significantly enhanced at day 10 AP, when NEFA concentration was also significantly increased. Milk yield and ECM value were depressed in +Cr group. DMI and BCS were significantly enhanced in +Cr group at day 7 BP. In conclusion, chromium modulates insulin signalling pathway in dairy cows, but targeted signalling molecules are different in antepartal then post-partal period, probably due to duration of exposure to chromium and different energy status between those periods.
Keywords:bovine / chromium / insulin signalling pathway
Source:Journal of Animal Physiology and Animal Nutrition, 2018, 102, 1, 41-55
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