Impacts of Time-Fed Concentrate-Based Diets on Plasma Metabolites, Rumen Histology, and mRNA Expression of Hepatic Enzymes of Wethers

Abstract

Transition to grain increases inflammation and causes parakeratosis, which can decrease growth performance in fattening animals. It is unknown if ruminants adapt to these inflammatory responses over time. In a three-phase, 49-day experiment, all wethers (n = 13, BW = 50.6 ± 4.7 kg; 4.9 ± 0.3 months of age) were fed an 80% forage diet during P1(day 0 to 21). On day 21, 4 wethers were slaughtered to obtain baseline liver and rumen tissue. During P2 (day 22 to 25), the remaining wethers were fed an 80% concentrate diet. Four wethers were slaughtered on day 25 to obtain P2 liver and rumen tissue. During P3 (day 22 to 49), the remaining five wethers were fed 80% concentrate diets and were slaughtered on day 49 to obtain P3 liver and rumen tissue. Rumen parakeratosis was greater (p ≤ 0.02) in wethers sampled in P2 and P3 when compared to those sampled in P1. Among positive acute phase reactants, expression of serum α-amyloid (SAA) and haptoglobin (HPT) tended (p ≤ 0.12) to be 6- and 10-fold greater, respectively, in wethers sampled in P2 compared to wethers sampled in P1; however, SAA and HPT expression was not different between wethers sampled in P3 and P1. Plasma glucose and β-hydroxybutyric acid (BHBA) increased (p ≤ 0.03) in wethers sampled in both P2 and P3 compared to the wethers sampled in P1, while total protein and cholesterol decreased (p ≤ 0.06) only in wethers sampled from P2 compared to those sampled in P1. Hepatic acute phase responses suggest that the wethers adapted to an 80% concentrate diet over time.

Ameliorative effects of supranutritional selenium on TLR‐4‐NF‐kB‐TNF‐α‐mediated hepatic oxidative injury and inflammation in goats fed high concentrate diet

“…Albumins represent 40–60% of total proteins in circulation and the decreased albumin concentrations is a consequence of reduced synthesis which may be due to increased utilization of amino acids for the synthesis of cytokines and APPs (Girardi et al, 2018 ; Tothova et al, 2014 ). In accordance with our findings, feeding HC diet downregulated ALB gene expression in sheep (Chishti et al, 2020 ). Supranutritional Se supplementation attenuated the expressions of HC diet‐induced APPs in liver.…”

“…HC diet‐derived LPS elicits acute phase response (APR) by regulating the synthesis and secretion of acute phase proteins (APPs) in liver thus any fluctuation in their concentrations in the peripheral blood reflects the functional disturbance and inflammation of liver (Guo et al, 2017 ; He et al, 2019 ; Minuti et al, 2015 ). Many studies have reported that HC diets increased levels of positive APPs and decreased negative APPs in peripheral blood of ruminants (Chandra et al, 2018 ; Ohtaki et al, 2020 ; Zhang et al, 2016 ) accompanied with alteration at transcriptional level in liver (Chishti et al, 2020 ; Li et al, 2019 ). Moreover, the modulation of hepatic APPs genes expressions in LPS‐challenged goats, sheep, and cattle (Cao et al, 2006 ; Jiang et al, 2008 ; Wang et al, 2017 ) indicate that HC diet induce hepatic inflammatory response through LPS translocated from GIT via portal vein (Chang, Zhang, Xu, Jin, Guo, et al, 2015 ; Chang, Zhang, Xu, Jin, Seyfert, et al, 2015 ).…”

“…The upregulation of Hp is linked with ruminal acidosis, damaged GIT wall and elevated blood LPS levels thus the overexpression of Hp has been considered as potential marker of severe ruminal acidosis in ruminants (Girardi et al, 2018 ). Hence, lack of effect of HC diet on Hp expression suggests gradual adaptation to concentrated diet over a period (Chishti et al, 2020 ).…”

“…On interaction with hepatocytes, the LPS stimulate innate immunity through acute phase proteins (APPs) modulation; thus, the resultant fluctuation in blood APPs concentrations reflects the functional disturbance and inflammation of liver (Guo et al, 2017 ; Minuti et al, 2015 ). APPs including serum amyloid A (SAA), α‐acid glycoprotein (AGP), LPS‐binding protein (LBP), haptoglobin (Hp), and albumin (ALB) have been found to be modulated by HC feeding (Chishti et al, 2020 ; Li et al, 2019 ; Ohtaki et al, 2020 ). LBP is highly sensitive to LPS, and its plasma levels drastically raise up to 200% in goats fed HC diets and hence considered as reliable biomarker of systemic inflammation (Chang, Zhang, Xu, Jin, Seyfert, et al, 2015 ; Dong et al, 2013 ).…”