Shifts in the Rumen Microbiota Due to the Type of Carbohydrate and Level of Protein Ingested by Dairy Cattle Are Associated with Changes in Rumen Fermentation

Abstract

Balancing energy and nitrogen in the rumen is a key to both profitability and environmental sustainability. Four dairy cows were used in a Latin square experimental design to investigate the effect of severe nitrogen underfeeding (110 vs. 80% of requirements) and the type of carbohydrate consumed [neutral detergent fiber rich (FIB) vs. starch rich (STA)] on the rumen ecosystem. These dietary treatments modified both rumen fermentation and microbial populations. Compared with STA diets, consumption of FIB diets increased bacterial and fungal diversity in the rumen and also increased the concentrations of cellulolytic microorganisms, including protozoa (+38%), anaerobic fungi (+59%), and methanogens (+27%). This microbial adaptation to fiber utilization led to similar digestibility values for the 2 carbohydrate sources and was accompanied by a shift in the rumen fermentation patterns; when the FIB diets were consumed, the cows had greater ruminal pH, ammonia concentrations, and molar proportions of acetate and propionate compared with when they consumed the STA diets. Certain rumen microorganisms were sensitive to a shortage of nitrogen; rumen concentrations of ammonia were 49% lower when the low-protein (LP) diets were consumed as were total bacteria (-13%), anaerobic fungi (-28%), methanogens (-27%), protozoa (-19%), cellulolytic bacteria, and microbial diversity compared with when the high-protein (HP) diets were consumed. As a result, the digestibility of the LP diets was less than that of the HP diets. These findings demonstrated that the rumen microbial ecosystem is directly linked to the rumen fermentation pattern and, to some extent, to the efficiency of diet utilization by dairy cattle.

Effects of dietary nitrogen levels and carbohydrate sources on apparent ruminal synthesis of some B vitamins in dairy cows

“…Dietary characteristics, such as carbohydrate source and protein supply, affect fermentation and microorganisms in the rumen (Johnson and Johnson, 1995;Hristov et al, 2001;Belanche et al, 2012). For example, easily fermentable carbohydrates, such as starch, are more efficient than other carbohydrates, such as cellulose, to promote microbial growth (Bach et al, 2005), whereas reduction in nitrogen supply can lead to a lower rumen microbial diversity and abundance (Belanche et al, 2012). To our knowledge, information on the effect of N level and carbohydrate source on B-vitamin apparent ruminal synthesis (ARS) is very limited.…”

Manipulating Protein Degradability in the Rumen to Support Higher Ruminant Production

“…Balancing energy and nitrogen in the rumen is a key to both profitability and environmental sustainability (Belanche et al 2012). This is supported by earlier finding of an experiment in sheep that synchronizing the rate of supply of N and energyyielding substrates to the rumen micro-organisms based upon ingredient in situ degradation data can improve microbial protein flow at the duodenum and the efficiency of microbial protein synthesis (Sinclair et al 1993).…”

“…Consumption of fiber rich diets increased bacterial and fungal diversity in the rumen and also increased the concentrations of cellulolytic microorganisms, including protozoa (+38%), anaerobic fungi (+59%), and methanogens (+27%) as compared to feeding starch rich diets in dairy cows (Belanche et al 2012). However, the orchestra of all microbes in the rumen is required to synergize overall effects on the feed degradation and fermentation.…”

Aspects of rumen adaptation in dairy cattle : morphological, functional, and gene expression changes of the rumen papillae and changes of the rumen microbiota during the transition period

“…In contrast, dry period rations generally contain predominantly lower quality forages (lower FOM, high fiber content, lower digestibility). The type and quantity of feed consumed leads to changes in the rate of substrate fermentation, rumen VFA concentrations, pH, and passage rate, which all interact to affect the composition of the microbiota community (Fernando et al, 2010;Belanche et al, 2012;McCann et al, 2014;. Various studies addressed this relationship between ration composition and the composition of the rumen microbiota (review by McCann et al, 2014).…”

“…The rumen microbiota is highly diverse, especially within the domain bacteria (Edwards et al, 2004;Kim et al, 2011), and its composition depends on the type and quantity of substrates ingested, and on host species and its physiological status (McCann et al, 2014;. The type and quantity of substrate consumed leads to changes in the rate of substrate fermentation, rumen VFA concentrations, pH, passage rate, and the composition of the microbiota (Fernando et al, 2010;Belanche et al, 2012). However, the capacity to ferment a wide range of substrates is likely to be maintained despite changes in microbiota community composition as a high degree of functional redundancy and resilience coincides with the diversity of the microbiota .…”