Effects of close-up dietary energy strategy and prepartal dietary monensin on hepatic mRNA expression of enzymes involved in glucose and lipid metabolism in transition cows

monensin;transition cows;close-up diet;glucose and lipid metabolism

Chen, Shuowen ; Loor ; Juan J.

关键词: monensin;    transition cows;    close-up diet;    glucose and lipid metabolism;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/45482/Shuowen_Chen.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

A two-stage feeding system for dry cows (far-off plus close-up groups) has been used by farmers for a long time. However, little basic research has been conducted to evaluate the effects of such approach on liver function. The objective of this study was to 1) to compare the effect of two different diets: one-stage controlled-energy high fiber diet (CON) fed throughout the entire dry period versus a two-stage diet (OVER) with controlled-energy in far-off period followed by higher energy in close-up period; and 2) to evaluate the effect of monensin (M) supplementation to these two different diets on bovine hepatic mRNA expression of enzymes involved in liver adaptive mechanisms during the transition period.The treatments were arranged in a 2 (one-stage CON or two-stage OVER feeding strategy) × 2 (inclusion of 0 or 22g/ton of M) factorial arrangement. The CON diet was formulated for a dietary energy concentration of 1.30 Mcal NEL/kg DM and the OVER diet for 1.49 Mcal NEL/kg DM. We calculated dry matter intake and analyzed serum NEFA and BHBA concentration and liver composition of the cows both prepartum and postpartum. We also examined mRNA expression at -14 and 7 via qPCR of gluconeogenesis genes (FBP1, PC, PCK1), fatty acid oxidation and ATP synthesis genes (CPT1A, ACOX1, ATP5G1), lipid metabolism genes (APOA1, APOB, FADS2, SCD, HMGCR), inflammation, acute phase response, and detoxification/oxidative stress genes (TNF, IL6, HP, GSTM1), growth hormone/IGF-1 axis genes (GHR, IGF1) and transcription factors (FOXA2, HNF4A, NR4A1, SREBPF2).In cows fed the CON diet, serum NEFA concentrations were higher at -2 and -1 week relative to calving and serum BHBA concentrations were also higher at -2 wk. We also observed a lower concentration of BHBA in cows fed monensin at 2 wk. Liver compositions and DMI were not affected by any of the treatments. Cows fed the CON diet had an up-regulated expression of CPT1A, APOA1, PC, PCK1 and a down-regulated expression of ATP5G1, SCD and GHR at -14 d. At 7 d, expression of GHR and IL6 was lower in cows fed CON diet than those fed OVER diet. Inclusion of monensin resulted in an increase in expression of SCD at 7 d and a decrease in APOA1 at -14 d in cows compared with the control group. Expression of IGF1 and GSTM1 was increased by monensin at -14 d. Based on these results, we conclude that the two-stage diet (OVER) had no advantage compared with the one-stage controlled energy-high fiber diet (CON) and inclusion of monensin had very little benefit in improving hepatic adaptations to metabolic changes in transition cows.