Comparative characterization of reticular and duodenal digesta and possibilities of estimating microbial outflow from the rumen based on reticular sampling in dairy cows1

Abstract

The objective of this experiment was to investigate the possibility of estimating the outflow of nutrients and microbial protein from the rumen based on sampling reticular contents as an alternative to duodenal sampling. Microbial protein flow estimates were also compared with a third method based on sampling of ruminal contents. Reticular and duodenal digesta and ruminal contents were recovered from 4 cows used in a 4 x 4 Latin square design experiment, in which the ruminal effects of 4 exogenous enzyme preparations were studied. Large and small particulate and fluid markers were used to estimate digesta flow in a triple-marker model; 15N was used as a microbial marker. Reticular and duodenal digesta were segregated into small and large particles (SP and LP, respectively) and a fluid phase, and ruminal digesta was segregated into particulate and fluid phases. Compared with digesta recovered at the duodenum, reticular digesta had lower OM and greater NDF contents. The proportion of microbial N was notably greater in the fluid phase of reticular digesta. Ruminal outflow of DM and OM was greater (by 17 and 28%) and that of NDF was lower (by 14%) when estimated from duodenal compared with reticular samples. There was no difference in the estimated flow of starch and nonammonia and microbial N between the reticular and duodenal techniques. Microbial N flow estimated based on ruminal sampling was similar to those based on duodenal and reticular sampling. The ruminal method, however, grossly overestimated flow of DM, OM, and NDF. This study supports the concept that microbial protein outflow from the rumen can be measured based on sampling of ruminal or reticular digesta. The reticular sampling technique can also provide reliable estimates for ruminal digestibility of OM, N, and fiber fractions. These findings need to be confirmed in experiments with basal diets varying in structure and forage-to-concentrate ratios.

Using archaeol to investigate the location of methanogens in the ruminant digestive tract

“…that is about to leave 322 the reticulo-rumen) as opposed to concentrations in the WRC. This is because digesta 323 from the reticulum is very similar to that found in the duodenum (Hristov, 2007) …”

Factors affecting the ruminal microbial composition and methods to determine microbial protein yield. Review

“…Microbial protein reaching the duodenum Glenn et al (86) PB Holstein steers 1,093 g/d Ipharraguerre et al . (89) PB Dairy cattle 1,825 g/d Cooper et al (85) PB Beef cattle 1,300 g/d Sylvester et al (83) rDNA Dairy cattle 1,693 g/d Schwab et al (90) LN Dairy cattle 2,137 g/d Moorby et al (88) Cytosine Dairy cattle 944 g/d Hristov et al (84) LN Dairy cattle 1,906 g/d Leupp et al (87) PB Beef cattle 545 g/d Belanche et al (8) PB Sheep 162 mg/g DM Belanche et al (8) rDNA Sheep 130 mg/g DM Castillo-Lopez et al (5) DAPA Beef cattle 473 g/d Castillo-Lopez et al (5) rDNA Beef cattle 561 g/d Castillo-Lopez et al (3) PB Dairy cattle 1,881 g/d Castillo-Lopez et al (3) rDNA Dairy cattle 1,262 g/d PB= Purine bases; DAPA= Diaminopimelic acid; LN= Labelled nitrogen ( 15 N).…”

Effect of feeding dried distillers grains with solubles on ruminal biohydrogenation, intestinal fatty acid profile, and gut microbial diversity evaluated through DNA pyro-sequencing

“…Microbial communities from samples collected in the rumen and duodenum clustered separately (Fig. Bacteria identified in intestinal contents could originate from lysed cells as they pass through the abomasum (Waghorn et al, 1990;Koenig et al, 1997;Hristov, 2007), and the function of the duodenal population is likely different than that of the ruminal bacterial community in terms of its role in feed digestion. More specifically, the phylum Fibrobacteres was lower (P < 0.01) in the rumen compared to the duodenum, with means averaged across diets of 0.13 and 10.1 ± 0.56% for the rumen and duodenum, respectively (Table 5).…”