Effects of the acid–base treatment of corn on rumen fermentation and microbiota, inflammatory response and growth performance in beef cattle fed high-concentrate diet

Abstract

Beef cattle are often fed high-concentrate diet (HCD) to achieve high growth rate. However, HCD feeding is strongly associated with metabolic disorders. Mild acid treatment of grains in HCD with 1% hydrochloric acid (HA) followed by neutralization with sodium bicarbonate (SB) might modify rumen fermentation patterns and microbiota, thereby decreasing the negative effects of HCD. This study was thus aimed to investigate the effects of treatment of corn with 1% HA and subsequent neutralization with SB on rumen fermentation and microbiota, inflammatory response and growth performance in beef cattle fed HCD. Eighteen beef cattle were randomly allocated to three groups and each group was fed different diets: low-concentrate diet (LCD) (concentrate : forage = 40 : 60), HCD (concentrate : forage = 60 : 40) or HCD based on treated corn (HCDT) with the same concentrate to forage ratio as the HCD. The corn in the HCDT was steeped in 1% HA (wt/wt) for 48 h and neutralized with SB after HA treatment. The animal trial lasted for 42 days with an adaptation period of 7 days. At the end of the trial, rumen fluid samples were collected for measuring ruminal pH values, short-chain fatty acids, endotoxin (or lipopolysaccharide, LPS) and bacterial microbiota. Plasma samples were collected at the end of the trial to determine the concentrations of plasma LPS, proinflammatory cytokines and acute phase proteins (APPs). The results showed that compared with the LCD, feeding the HCD had better growth performance due to a shift in the ruminal fermentation pattern from acetate towards propionate, butyrate and valerate. However, the HCD decreased ruminal pH and increased ruminal LPS release and the concentrations of plasma proinflammatory cytokines and APPs. Furthermore, feeding the HCD reduced bacterial richness and diversity in the rumen. Treatment of corn increased resistant starch (RS) content. Compared with the HCD, feeding the HCDT reduced ruminal LPS and improved ruminal bacterial microbiota, resulting in decreased inflammation and improved growth performance. In conclusion, although the HCD had better growth performance than the LCD, feeding the HCD promoted the pH reduction and the LPS release in the rumen, disturbed the ruminal bacterial stability and increased inflammatory response. Treatment of corn with HA in combination with subsequent SB neutralization increased the RS content and helped counter the negative effects of feeding HCD to beef steers.

Sodium Butyrate More Effectively Mitigates the Negative Effects of High-Concentrate Diet in Dairy Cows than Sodium β-Hydroxybutyrate via Reducing Free Bacterial Cell Wall Components in Rumen Fluid and Plasma

“…Several studies have suggested that HC diet also led to an increase of iE-DAP in the rumen and plasma [ 14 , 40 ]. In this present study, the HC diet significantly increased LPS concentration in plasma, which was in line with previous reports [ 1 ]. Our study also showed the HC diet significantly increased concentrations of LTA and PGN in plasma.…”

“…Compromised rumen epithelium barrier allows the PAMPs to easily cross the rumen epithelium into the peripheral blood [ 3 ]. Thus, HC diet not only elevates LPS concentration in rumen fluid, but also results in a rise in plasma [ 1 , 2 ]. Several studies have suggested that HC diet also led to an increase of iE-DAP in the rumen and plasma [ 14 , 40 ].…”

“…Elevated PAMP concentrations in blood circulation can cause systemic and local immune responses [ 44 , 45 ] and significantly increase the concentrations of proinflammatory cytokines (IL-1 β , IL-6, IL-8, and TNF- α ) and APPs (LBP, SAA, CRP, and Hp) [ 1 , 2 , 3 ]. In the present study, the HC diet significantly increased the concentrations of proinflammatory cytokines and APPs in plasma, which was consistent with previous studies [ 1 , 2 , 3 ]. In addition, when immune responses are activated, the number of immune cells will markedly increase in the blood.…”

“…However, HC diet often results in subacute ruminal acidosis (SARA). During the occurrence and development of SARA, the microbial communities in the rumen are disturbed, and the richness and diversity of rumen microbes are decreased [ 1 , 2 ]. Meanwhile, large amounts of bacterial cell wall components are released into rumen fluid [ 3 ].…”

Active Rumen Bacterial and Protozoal Communities Revealed by RNA-Based Amplicon Sequencing on Dairy Cows Fed Different Diets at Three Physiological Stages

“…The highest diversity of active rumen bacteria during the DP stage reported in the present study is in agreement with other DNA/RNA-based studies [ 48 , 49 ] and is probably related to the high forage content in the diet. High ruminal bacterial diversity with high-forage diets and low bacterial diversity with high-concentrate diets have been already reported [ 50 , 51 ]. Similar negative impacts of a high-concentrate diet on bacterial species richness and diversity have been discussed by Zhang et al [ 52 ] and Pinto et al [ 53 ].…”