Specific enrichment of microbes and increased ruminal propionate production: the potential mechanism underlying the high energy efficiency of Holstein heifers fed steam-flaked corn

Abstract

Corn grain is high in starch content and is primarily used as an energy source in ruminant diets. Compared with finely ground corn (FGC), steam-flaked corn (SFC) processing could improve the milk yield of lactating dairy cows and the growth performance of feedlot cattle, but the detailed mechanisms underlying this finding are unknown. The rumen microbiome contributes to feed efficiency by breaking down feedstuffs into energy substrates that can subsequently be utilized by the host animal. Therefore, the current study was conducted to investigate the ruminal bacterial community of heifers fed differently processed corn (SFC or FGC) with the same forage-to-concentrate ratio using 16S rRNA sequencing technologies and to uncover the detailed mechanisms underlying the high performance of ruminants fed the SFC diet. The results revealed that different processing methods resulted in changes in rumen characteristics and impacted the composition of the rumen bacterial structure. The SFC diet resulted in an increased average daily gain in heifers, an increased rumen propionate concentration and a decreased ammonia nitrogen concentration. The relative abundance of the phylum Firmicutes tended to increase and the relative abundance of the phylum Proteobacteria significantly increased in the heifers fed SFC diet compared with FGC diet. In addition, the relative abundance of amylolytic bacteria of the genera Succinivibrio , Rosebuia and Blautia ere evaluated, and cellulolytic bacteria (Ruminococcaceae_UCG-014 and Ruminococcaceae_UCG-013 ) decreased by the steam flaking method. Spearman correlation analysis between the relative abundances of the ruminal bacteria and the microbial metabolites showed that the rumen propionate concentration was positively correlated with Succinivibrio and Blautia abundance and negatively correlated with Ruminococcaceae_UCG-014 abundance. Evident patterns of efficient improvement in rumen propionate and changes in rumen microbes to further improve feed conversion were identified. This observation uncovers the potential mechanisms underlying the increased efficiency of the SFC processing method for enhancing ruminant performance.

Ruminal Fermentation Pattern, Bacterial Community Composition, and Nutrient Digestibility of Nellore Cattle Submitted to Either Nutritional Restriction or Intake of Concentrate Feedstuffs Prior to Adaptation Period

“…These findings may explain the lower propionate concentration, as members of the Succinivibrio and Bacteroidales are known starch degraders in the rumen and found in high abundance when cattle are fed high-grain diets containing large amounts of starch or rapidly fermentable carbohydrates ( Zhang et al, 2018 ). Ren et al (2019) also reported that the relative abundance of amylolytic Succinivibrio increased as the availability of starch in the diet increased, resulting in a positive correlation with propionate concentration in the rumen, which is in agreement with the results observed in this study.…”

“…This can present problems, such as the aforementioned ruminal acidosis, during the finishing period and negatively impact animal health and productivity. For example, the inclusion of small amounts of grain (10 to 20%) in the pre-adaptation diet prior to feedlot arrival may trigger ruminal acidosis by ensuring that adequate numbers of amylolytic microorganisms, such as those from the genus Succinivibrio , are present to ferment the carbohydrates in the adaptation and finishing diet ( Nagaraja and Titgemeyer, 2007 ; Nagaraja, 2016 ; Ren et al, 2019 ). Cattle that are nutritionally restricted to grazing on poor-quality tropical grasses prior to intake of a high-concentrate diet may respond negatively to the rapid influx of concentrate present in the adaptation diet and develop ruminal acidosis.…”

Effects of Paper Mulberry Silage on the Milk Production, Apparent Digestibility, Antioxidant Capacity, and Fecal Bacteria Composition in Holstein Dairy Cows

“…The different breed and feeding management can be attributed to the inconsistency of the domain genus. The Ruminococcaceae family is related to cellulose and hemicellulose degradation [ 56 ]. Diets with PM silage changed the carbohydrate resource and the fiber decomposition process may contribute to the difference between the Ruminococcaceae UCG-013 genus and other Ruminococcaceae genera [ 56 ].…”

“…The Ruminococcaceae family is related to cellulose and hemicellulose degradation [ 56 ]. Diets with PM silage changed the carbohydrate resource and the fiber decomposition process may contribute to the difference between the Ruminococcaceae UCG-013 genus and other Ruminococcaceae genera [ 56 ]. Previous studies have indicated that the large intestine of cattle contains a small quantity of fiber and starch [ 57 ], and that the large intestine is an important organ for digesting undigested feed, suggesting that PM silage supplementation can have a positive influence on fiber degradation in the upper gut and consequently decrease the cellulolytic bacteria of the hindgut.…”

Specific rumen microbiome traits predict average daily gain in beef cattle under different backgrounding systems

“…Succinivibrionacae are reported to be core taxa in beef cattle and one of the most active bacteria during growing and finishing stages [8,33]. Members of this family, including Selenomonas, and Succinivibrio, have been observed to increase in the rumen of steers when suppressing methanogens using encapsulated nitrates, and in positive association with high energy diets, ADG and feed efficiency [34][35][36][37].…”