Assessment of Ruminal Bacterial Populations and Protozoal Generation Time in Cows Fed Different Methionine Sources

Abstract

Methionine supplemented as 2-hydroxy-4-(methylthio)-butanoic acid (HMB) has been suggested to alter bacterial or protozoal populations in the rumen. Our objective was to determine if source of Met would change microbial populations in the rumen and to compare those results to samples from the omasum. The ruminal and omasal samples were collected from cows fed control (no Met), dl-Met, HMB, or the isopropyl ester of HMB (HMBi; estimated 50% rumen protection) in a replicated 4 x 4 Latin square design. In one square, changes in protozoal populations were determined using microscopic counts and denaturing gradient gel electrophoresis (DGGE), whereas changes in bacterial populations were determined using DGGE and ribosomal intergenic spacer length polymorphism (RIS-LP). Neither the protozoal counts nor the DGGE banding patterns derived from protozoa were different among the dietary treatments or for ruminal vs. omasal samples. As revealed by both DGGE and RIS-LP, bacterial populations clustered by treatments in ruminal and especially in omasal samples. Using cows from both Latin squares, the flow of protozoal cells from the rumen was quantified by multiplying protozoal cell count in omasal fluid by the omasal fluid flow (using CoEDTA as a liquid flow marker) or was estimated by rumen pool size of cells multiplied by either the ruminal dilution rate of CoEDTA (after termination of CoEDTA dosing) or the passage rate of Yb-marked particles. Compared with the omasal fluid flow measurement (16.4 h), protozoal generation time was approximated much more closely using the particulate than the fluid passage rate from the rumen (generation times of 15.7 and 7.5 h, respectively). There seems to be minimal selective retention of protozoal genera in the rumen in dairy cattle fed every 2 h. Data support the validity of the omasal sampling technique under our conditions.

Strategies for optimizing nitrogen use by ruminants

“…The contribution of protozoal N flow to the total microbial flow to the duodenum may be quantitatively important and may affect our current estimates of ENU, but there are limited data available to fully evaluate its impact on overall efficiency of N utilization (Karnati et al, 2007). There has also been a long discussion on the potential role of protozoa on rumen metabolism (Jouany, 1996;Williams and Coleman, 1997).…”

Feeding ruminally protected methionine to pre- and postpartum dairy cows: effect on milk performance, milk composition and blood parameters

“…Literature dealing with the use of ruminally protected methionine in dairy cows is extensive. There are reports on effects on milk performance and physiological measures (Rogers et al, 1987;Donkin et al, 1989;Blum et al, 1999;Pisulewski and Kowalski, 1999;Misciattelli et al, 2003), reports on the effect on rumen microorganisms (Noftsger et al, 2005;Karnati et al, 2007) as well as reports on effects during the periparturient period and in the course of lactation (Bach et al, 2000;Piepenbrink et al, 2004;Foroughi et al, 2005;Socha et al, 2005). Rumen protection of methionine is based on chemical derivatization or physical protection by coating.…”

Developmental microbial ecology of the crop of the folivorous hoatzin

“…The microarray approach revealed an unprecedented diversity with B1400 OTUs grouped in 40 phyla (7 of which were also detected by cloning) in comparison, with previous studies on the human gut (14 phyla (Andersson et al, 2008)), cow rumen (12 phyla (Tajima et al, 2001;Ozutsumi et al, 2005;Karnati et al, 2007)) chicken ceca (5 phyla (Lan et al, 2002;Zhu et al, 2002)) and other gastrointestinal tracts of several mammalian (overall 22 phyla ). The high number of phyla was partially confirmed by the rarefaction's curves at 80% sequence homology and the high OTU-level richness was also confirmed by the estimated values previously published (GodoyVitorino et al, 2008).…”