Long-term high-grain diet altered the ruminal pH, fermentation, and composition and functions of the rumen bacterial community, leading to enhanced lactic acid production in Japanese Black beef cattle during fattening

Abstract

To increase intramuscular fat accumulation, Japanese Black cattle are commonly fed a high-grain diet from 10 to 30 months of age although it can result in the abnormal accumulation of organic acids in the rumen. We explored the effect of long-term high-concentrate diet feeding on ruminal pH and fermentation, and its effect on the rumen bacterial community in Japanese Black beef cattle during a 20-month fattening period. Nine castrated and fistulated Japanese Black beef cattle were housed with free access to food and water throughout the study period (10–30 months of age). The fattening stages included Early, Middle, and Late stages (10–14, 15–22, and 23–30 months of age, respectively). Cattle were fed high-concentrate diets for the experimental cattle during fattening. The body weight of the cattle was 439 ± 7.6, 561 ± 11.6, and 712 ± 18.5 kg (mean ± SE) during the Early, Middle, and Late stages, respectively. Ruminal pH was measured continuously during the final 7 days of each stage, and rumen fluid and blood samples were collected on day 4 (fourth day during the final 7 days of the pH measurements). The 24-h mean ruminal pH during the Late stage was significantly lower than that during the Early stage. Total volatile fatty acid (VFA) during the Late stage was significantly lower than during the Early and Middle stages, but no changes were noted in individual VFA components. The lactic acid concentration during the Late stage was significantly higher than that during the Early and Middle stages. The bacterial richness indices decreased significantly during the Late stage in accordance with the 24-h mean ruminal pH. Among the 35 bacterial operational taxonomic units (OTUs) shared by all samples, the relative abundances of OTU8 (Family Ruminococcaceae) and OTU26 (Genus Butyrivibrio) were positively correlated with the 24-h mean ruminal pH. Total VFA concentration was negatively correlated with OTU167 (Genus Intestinimonas), and lactic acid concentration was correlated positively with OTU167 and OTU238 (Family Lachnospiraceae). These results suggested that long-term high-grain diet feeding gradually lowers ruminal pH and total VFA production during the Late fattening stage. However, the ruminal bacterial community adapted to feeding management and the lower pH during the Late stage by preserving their diversity or altering their richness, composition, and function, to enhance lactic acid production in Japanese Black beef cattle.

Long-term high-grain diet alters ruminal pH, fermentation, and epithelial transcriptomes, leading to restored mitochondrial oxidative phosphorylation in Japanese Black cattle

“…In cattle, a ruminal pH below the physiological range of 5.8-6.5 6 can induce inflammatory responses 15 , and structural or transcriptomic changes in the RE [8][9][10] . Consistent with a previous study 14 , the 24 h mean ruminal pH decreased gradually as the lengths of time at pH <5.6 and <5.8 increased during the middle and late stages of fattening as a result of a long-term high-grain diet. These observations are sufficient to diagnose SARA during the middle and late stages (ruminal pH <5.6 or <5.8 for more than 3 or 5 h per day, respectively 16,17 ;).…”

“…Daily dietary intake, ruminal pH, total VFA, LPS, and LBP. In this study, we re-analyzed our previously published data regarding rumen fermentation parameters 14 to evaluate the relationships between ruminal pH and candidate gene expression in the RE.…”

“…No adverse health condition throughout the study period and effects of ruminal cannulation after surgery were observed for any of the cattle. The daily intake and rumen fermentations were described previously 14 . Briefly, the organic matter basis concentrate intake was significantly (P < 0.05) higher during the Middle stage than during the early and late stages (7.6 vs. 6.0 and 6.1 kg/day, respectively), and the forage diet intake was significantly (P < 0.05) higher during the early stage than the middle and late stages (2.1 vs. 1.1 and 1.0 kg/day, respectively).…”

“…During the fattening period, Japanese Black beef cattle are raised on a high-grain diet between 10 and 30 months of age to increase intramuscular fat accumulation. In this study, samples were collected throughout the entire fattening period to explore the long-term changes in ruminal pH and fermentation as described previously 14 , and their consequences for rumen epithelial transcriptomic dynamics. In cattle, a ruminal pH below the physiological range of 5.8-6.5 6 can induce inflammatory responses 15 , and structural or transcriptomic changes in the RE [8][9][10] .…”

Association between Rumen Microbiota and Marbling Score in Korean Native Beef Cattle

“…Among the differentially abundant taxa listed for the LMS group, Olsenella is considered a lactate and succinate producer [50] and its abundance continuously increases during fattening in high-grain diet-fed beef cattle [51]. HMS-enriched Paludibacter, a bacterial genus of Porphyromonadaceae, ferments glucose to produce acetate and propionate as the major fermentation products [52], the former of which is a lipogenic precursor.…”