Betaine addition as a potent ruminal fermentation modulator under hyperthermal and hyperosmotic conditions in vitro

Abstract

BACKGROUND Climatic and dietary shifts predispose ruminal microbes to hyperthermal and hyperosmotic stress, leading to poor fermentation and subsequently adverse effects on ruminant productivity. Betaine may function as substrate, osmolyte, antioxidant, and methyl donor for microbes. However, its effect depends on the extent of microbial catabolism. This study revealed the ruminal disappearance kinetics of betaine and its dose effect on ruminal fermentation during thermal and osmotic stress using a rumen simulation technique. RESULTS Three different betaine doses were used: 0, 50, and 286 mg L−1; each was assigned to two incubation temperatures (39.5 and 42 °C) and two osmotic conditions (295 and 420 mOsmol kg−1). Betaine disappeared rapidly within the first 6 h of incubation; however, the rate was lower during hyperosmotic stress (P < 0.05), the stress condition that also suppressed the overall fermentation and degradation of organic nutrients and decreased the bacterial diversity (P < 0.001). During hyperosmotic stress, betaine shifted the fermentation pathway to more propionate (P < 0.05). Betaine counteracted the negative effect of hyperthermal stress on total short‐chain fatty acid concentration (P < 0.05) without affecting the composition. Both stress conditions shifted the bacterial composition, but the effect of betaine was minimal. CONCLUSION Despite its rapid ruminal disappearance, betaine modulated microbial fermentation in different ways depending on stress conditions, indicating the plasticity of the betaine effect in response to various kinds of physicochemical stress. Although betaine did not affect the abundance of ruminal microbiota, the enhanced fermentation suggests an improved microbial metabolic activity under stress conditions. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Betaine Modulates Rumen Archaeal Community and Functioning during Heat and Osmotic Stress Conditions In Vitro

“…The trial was performed using two Rusitec assemblies described in detail earlier [ 3 ]. In brief, each Rusitec assembly contained 6 fermenters placed in a water bath, with each fermenter having an effective volume of 800 mL.…”

“…The forage portion of the diet contained on dry matter basis grass silage (25% in normal, 20% in osmotic stress), corn silage (15% in normal, 7% in osmotic stress), and second-cut meadow hay (10% in normal, 8% in osmotic stress). The concentrate mixture (43% in normal, 56% in osmotic stress) consisted of barley (21.55%), wheat (21.55%), maize (51.7%), and vitamin and mineral supplements (5.2%), in addition to Rindastar (Schaumann, Germany) protein concentrate which was used as protein source (7% in normal, 9% in osmotic stress) [ 3 ]. The chemical compositions of both diets has already been reported in detail in another parallel study [ 3 ].…”

“…The concentrate mixture (43% in normal, 56% in osmotic stress) consisted of barley (21.55%), wheat (21.55%), maize (51.7%), and vitamin and mineral supplements (5.2%), in addition to Rindastar (Schaumann, Germany) protein concentrate which was used as protein source (7% in normal, 9% in osmotic stress) [ 3 ]. The chemical compositions of both diets has already been reported in detail in another parallel study [ 3 ]. The normal osmolality condition was maintained with the infusion of McDougall's salivary buffer [ 21 ] with small modifications along with the use of diet containing 50 : 50 ratio of forage : concentrate.…”

“…Betaine or trimethyl glycine is a zwitterionic, compatible, and widely available organic osmolyte, which is either synthesized or picked up by the microbes to equilibrate their ionic balance and cell turgor [ 1 – 3 ]. Betaine also stabilizes the native protein structure of the cell and prevents molecular disintegration, acting as a molecular chaperone and intracellular antioxidant [ 4 , 5 ].…”

“…Betaine is found naturally abundant in wheat bran and sugar beet, both animal feed products, and it has been previously shown to reduce the effects of environmental and dietary changes on the gastrointestinal microbiota [ 3 , 6 , 7 ]. Our previous research looking at the impact of betaine under high temperature and increased osmolality conditions on rumen found that the application of betaine in vitro resulted in a stabilization of the bacterial population and improved ruminal fermentation [ 3 ]. It is reasonable to expect that the presence of betaine could also affect rumen archaea community and functioning.…”