Microbiome-Metabolome Responses in Ruminal Content and Feces of Lactating Dairy Cows With N-Carbamylglutamate Supplementation Under Heat Stress

Abstract

The objective of the present study was to investigate the effects of N-carbamylglutamate (NCG) supplementation on metabolic profile and microbiota in ruminal content and feces of lactating dairy cows under heat stress (HS). Forty-eight lactating Holstein cows (154 ± 13.6 days in milk) were assigned randomly to four treatments (n = 12), to receive 0, 15, 20, or 25 g/day of commercial NCG (proportion: 97.7%) for the period of 60 days. The recorded ambient temperature–humidity index (THI) suggested that the cows were exposed to HS for almost the entire experimental period (average THI: 80.6). Samples of ruminal content and feces were collected at the end of the trial (day 60) to determine the biological effects of NCG supplementation on metabolome and microbiota using mass spectrometry-based metabolomics and 16S rRNA gene sequencing techniques, respectively. Results showed that NCG supplementation enhanced the levels of ruminal microbial protein, total volatile fatty acids (VFAs), and the molar proportion of propionate in the rumen, but lowered the ruminal pH, ammonia nitrogen (NH3-N), and the ratio of acetate to propionate. NCG at doses of 20 and 25 g/day reduced the community richness and diversity of ruminal microbiota with the decrease of Shannon and Simpson diversity. Compositions of ruminal and fecal microbiotas were altered by NCG, and the PICRUSt results revealed that metabolic pathways of the bacteria, such as amino acid metabolism, energy metabolism, and pyruvate metabolism, were enriched in NCG groups. Distinct changes in the metabolomic profile of ruminal fluid were observed between the control and NCG groups. Changes of 26 metabolites mainly involved in arginine metabolism, glutamate metabolism, and nitrogen metabolism were observed associated with NCG supplementation. These results provided new insights into the effects of NCG on metabolomic profile and microbiota in ruminal content and feces, and the optimal dose of NCG supplemented to dairy cows was 20 g/hd/day, which contributed to understanding the effects of NCG on HS in lactating dairy cows.

N-carbamylglutamate supplementation regulates hindgut microbiota composition and short-chain fatty acid contents in Charollais and Small Tail Han crossbred sheep

“…Observations by Zhang et al ( 16 ) demonstrated that dietary NCG supplementation ameliorated the diminished abundance of Clostridium , Lactobacillus , and Streptococcus within the colonic mucosa of lambs beset by intrauterine growth restriction. Likewise, Li et al ( 17 ) noted that NCG supplementation invoked an elevation in unidentified_Prevotellaceae coupled with a decrease in Acetitomaculum , Marvinbryantia , and unidentified_Christensenellaceae within the fecal microbiome of heat-stressed lactating dairy cows. In line with this, our investigation revealed a consistent pattern of effects following NCG supplementation.…”

The impact of different diets and genders on fecal microbiota in Hanwoo cattle

“…Similarly, the abundance of Blautia was lower in heifers fed a high forage diet for breeding than in those fed the late fattening diet including high concentrate. Marvinbryantia , which is present in the human gut and has the ability to degrade cellulose [ 40 ], was also found in the feces of cattle [ 41 ]. Since Marvinbryantia is more abundant in early fattening heifers than in early fattening steers, this genus may be affected by gender.…”