Dynamic changes and characterization of the protein and carbohydrate fractions of native grass grown in Inner Mongolia during ensiling and the aerobic stage

Abstract

Objective: To improve the utility of native grass resources as feed in China, we investigated the dynamics of protein and carbohydrate fractions among Inner Mongolian native grasses, during ensiling and the aerobic stage, using the Cornell Net Carbohydrate and Protein System.Methods: Silages were prepared without or with lactic acid bacteria (LAB) inoculant. We analyzed the protein and carbohydrate fractions and fermentation quality of silages at 0, 5, 15, 20, 30, and 60 d of ensiling, and the stability at 0.5, 2, 5, and 10 d during the aerobic stage.Results: Inner Mongolian native grass contained 10.8% crude protein (CP) and 3.6% water-soluble carbohydrates (WSC) on a dry matter basis. During ensiling, pH and CP and WSC content decreased (p<0.05), whereas lactic acid and ammonia nitrogen (N) content increased (p<0.05). Non-protein N (PA) content increased significantly, whereas rapidly degraded true protein (PB<sub>1</sub>), intermediately degraded true protein (PB<sub>2</sub>), total carbohydrate (CHO), sugars (CA), starch (CB<sub>1</sub>), and degradable cell wall carbohydrate (CB<sub>2</sub>) content decreased during ensiling (p<0.05). At 30 d of ensiling, control and LAB-treated silages were well preserved and had lower pH (<4.2) and ammonia-N content (<0.4 g/kg of fresh matter [FM]) and higher lactic acid content (>1.0% of FM). During the aerobic stage, CP, extract ether, WSC, lactic acid, acetic acid, PB<sub>1</sub>, PB<sub>2</sub>, true protein degraded slowly (PB<sub>3</sub>), CHO, CA, CB<sub>1</sub>, and CB<sub>2</sub> content decreased significantly in all silages, whereas pH, ammonia-N, PA, and bound true protein (PC) content increased significantly.Conclusion: Control and LAB-treated silages produced similar results in terms of fermentation quality, aerobic stability, and protein and carbohydrate fractions. Inner Mongolian native grass produced good silage, nutrients were preserved during ensiling and protein and carbohydrate losses largely occurred during the aerobic stage.

Characteristics of lactic acid bacteria, microbial community and fermentation dynamics of native grass silage prepared in Inner Mongolian Plateau

“…In this study, during the ensiling, WSC was transformed into organic acid, ethanol, and carbon dioxide by microorganisms, resulting in high DM content that inhibited the growth of Clostridium spp., which often produces butyric acid and ammonia nitrogen in silage material ( McEniry et al, 2011 ; Muck et al, 2018 ; Wang et al, 2018 ). Overall, the lower CP and WSC and higher NDF and ADF agreed with our previous study in meadow steppes ( Hou et al, 2017 ; Du et al, 2020 ; You et al, 2021a ).…”

Effects of Lactic Acid Bacteria and Molasses Additives on Dynamic Fermentation Quality and Microbial Community of Native Grass Silage

“…During the ensiling process of native grass, the content of CP significantly decreased. This was mostly due to the fact that some microorganisms involved in silage fermentation degrade protein ( Du Z. M. et al, 2020 ). Sufficient content of WSC could provide more substance for lactic acid fermentation.…”

“…Ensiling mainly depends on lactic acid bacteria to transfer soluble carbohydrates to lactic acid, resulting in a low pH environment and inhibiting the growth of aerobic bacteria, making the feed preserved ( Lee et al, 2018 ) and improving palatability ( Driehuis, 2013 ). Ensiling has been shown in previous research to improve fermentation quality while also preserving the nutrients of natural grass, resulting in a high feeding value ( Khota et al, 2016 ; Du Z. M. et al, 2020 ). However, due to the low water content, low water soluble carbohydrate, low lactic acid bacteria attachment, and high buffer energy of natural forage, direct silage is difficult to succeed ( Zhang et al, 2016 ; Hou et al, 2017 ).…”

Use of rizostar in the production of sorghum silages

“…The silage with application of 45 kg ha -1 of Rizostar in the sowing had greater DIGDM, since this is directly affected by CP, NDF and lignin, in addition to being the result of the combination of both fractions, together with the other fractions of carbohydrates in feed (Du, Risu, Gentu, Jia & Cai, 2020). The greater the digestibility of FC, and the less encrusted they are by the lignin present in the feed, the greater the digestibility of their dry matter.…”

“…These fractions correspond to the fibrous carbohydrates of the feed, which, due to their slow digestion (Du et al, 2020) and give the fodder a low nutritional value, evidenced by the low RVF.…”