Modulation of rumen fermentation and microbial community through increasing dietary cation–anion difference in Chinese Holstein dairy cows under heat stress conditions

Abstract

Aims The effect of increasing dietary cation–anion difference (DCAD) on rumen fermentation and ruminal microbial community in dairy cows under heat stress (HS) conditions were evaluated. Methods and Results This study was performed as a two‐period cross‐over design during the summer season, with eight lactating dairy cows randomly distributed to either a control DCAD diet (CON: 33·5 mEq/100 g DM) or high DCAD diet (HDCAD: 50·8 mEq/100 g DM). Throughout the present study, the temperature and humidity index (THI; 80·2 ± 4·29) was generally elevated above the threshold (THI = 72) that is reported to cause HS in lactating dairy cows. Rumen liquid samples were collected on 15 and 21 d during each 21 d‐period. The absolute concentration of ruminal total volatile fatty acid (TVFA) in HDCAD treatment was significantly (P < 0·05) higher than those in the control, whilst the ruminal pH, NH3‐N, and VFA molar percentages were unaffected through increasing DCAD. Furthermore, the copy numbers of the cellulolytic bacteria Ruminococcus albus and Ruminococcus flavefaciens in rumen fluid significantly (P < 0·05) rose along with the increment of DCAD. Although the Alpha diversity indexes and the bacterial microbiota structure were unaffected, increasing DCAD significantly (P < 0·05) enriched the phylum Fibrobacteres and genus Fibrobacter in the microflora of rumen fluid, whilst the genera Flexilinea and Dubosiella were the most differentially abundant taxa in the control. Conclusions Increasing DCAD under HS conditions resulted in a greater concentration of total VFA without affecting rumen bacteria diversity or structure, although the enrichment of some cellulolytic/hemicellulolytic bacteria was observed. Significance and Impact of the Study The present study provides information on the modulation of rumen fermentation and microbial community through the increment of DCAD in Holstein dairy cows under HS conditions.

Fermented Soybean Meal Replacement in the Diet of Lactating Holstein Dairy Cows: Modulated Rumen Fermentation and Ruminal Microflora

“…Many studies, including our previous investigations, have verified that Bacteroidetes, Firmicutes, and Proteobacteria are primarily the three most predominant bacterial phyla existing within the rumen ecosystem despite different ages or regions of the ruminants, employing the 16S rRNA amplicon sequencing based on either DNA or RNA isolated from the rumen contents (Jami et al, 2013;Rey et al, 2014;Liu et al, 2016;Wang et al, 2016aWang et al, , 2017aWang et al, , 2020c. The current trial also showed that the ruminal microbiota at the phylum level was sequentially dominated by Firmicutes, Bacteroidetes, and Proteobacteria via the full-length 16S rRNA gene sequencing, which further confirmed the conclusions of previous studies.…”

Bacillus amyloliquefaciens TL106 protects mice against enterohaemorrhagic Escherichia coli O157:H7‐induced intestinal disease through improving immune response, intestinal barrier function and gut microbiota

“…Information on the ecology and biology of Dubosiella is scarce, and the differentiation mechanism of the above taxa among different treatments in this experiment are undefined, so further investigations are necessary (Wang et al . 2020a, 2020b). We conclude that oral administration of TL106 to mice improved gut microflora and enhanced intestinal health in mice.…”

Supplementary Practices Improving Holstein Cattle Performance During Hot Seasons

“…The treatment group tended to visit drinking troughs more frequently compared with the control group. Therefore, Wang et al (2020) recommended supplementation of an appropriate electrolyte dose for Bos Taurus exposed to heat stress, that enhanced milk production in the treatment group, while the fat % was decreased logically.…”

“…Abdelatty et al (2018) and Conte et al (2018) observed that the hyperthermia led to increase respiratory rate accompanied by panting that decreased the HCO 3 buffer levels in saliva and blood and contributed to an increase in incidence rate of ruminal acidosis where acetate concentrations and acetate to propionate ratios increased significantly. The threshold of heat stress in dairy cattle was reported to be above 72 temperature-humidity index (THI) (Wang et al, 2020). Recently, many management plans were set to avoid heat stress consequences that are considered one of the main climatic change's manifestations.…”

“…Potassium deficiency could cause a reduction in dairy cow production. This deficiency may occur through some conditions like K + secretion via milk representing about 15 to 40% of total daily K intake, high environmental temperatures that led to an increase in potassium loss via sweating (Atrian & Shahryar, 2012;Wang et al, 2020), and low potassium content in animal feeding.…”