Effects of ruminal dosing of Holstein cows with Megasphaera elsdenii on milk fat production, ruminal chemistry, and bacterial strain persistence

Abstract

Megasphaera elsdenii is a lactate-utilizing bacterium whose ruminal abundance has been shown to be greatly elevated during milk fat depression (MFD). To further examine this association, a total of 23 cannulated multiparous Holstein cows were examined in 3 experiments in which strains of M. elsdenii were directly dosed into the rumen (~2 × 10(12) cells/dose); control cows were dosed with sterile lactate-free culture medium. Cows were fed a total mixed ration (292 g of starch/kg of dry matter) that contained primarily corn silage, alfalfa silage, finely ground high-moisture corn, supplemental protein, and corn oil (3 g/kg of dry matter). Experiments differed in stage of lactation of the cows (early or late), dosing events (single dose, or 4 doses over a 5-d period), timing of dose (prefeed or 4 h postfeed), and M. elsdenii strain (laboratory strain YI9 or 3 strains isolated from cows in the same herd). Dry matter intake and milk yield and composition were measured from 5 to 0 d before dosing and 1 to 7d after first dosing, plus later time points that varied by experiment. Milk yield and composition were not affected by dosing. Megasphaera elsdenii was quantified in the liquid phase of ruminal contents by automated ribosomal intergenic spacer analysis, or by PCR with relative quantification (M. elsdenii 16S rRNA gene copy number as a percentage of total bacterial 16S rRNA gene copies). Neither the M. elsdenii-dosed or control cows displayed MFD after dosing, and in almost all cases M. elsdenii populations returned to low baseline levels (<0.02% of 16S rRNA gene copy number) within 24 h of dosing. This rapid decline in M. elsdenii also occurred in several cows that were dosed with a strain of M. elsdenii that had been isolated from that particular cow during a previous bout of MFD. Ruminal pH and total millimolar volatile fatty acids and lactate did not differ between dosed and control cows, although acetate-to-propionate ratio declined in both groups and butyrate increased after dosing with M. elsdenii. The results confirm that establishing exogenously added bacterial strains in the rumen is difficult, even for strains previously isolated from the recipient cow. The potential role of M. elsdenii as an agent of MFD remains unclear in the absence of successful establishment of the dosed strains.

Review: The compositional variation of the rumen microbiome and its effect on host performance and methane emission

“…Interestingly, previous studies attempted to enrich the rumen of cows with M. elsdenii isolated from the rumen, in order to stabilize ruminal pH by decreasing lactate concentration and alter VFA profile toward increasing acetate and butyrate production (Zebeli et al, 2012;Weimer et al, 2015). Despite being unsuccessful in stably transplanting the bacteria and altering rumen composition, focusing on this species or other lactate utilizers may represent an interesting avenue worth pursuing for the purpose of both increased feed efficiency and methane mitigation.…”

Rumen microbiota and dietary fat: a mutual shaping

“…Because M. elsdenii has been shown to produce trans ‐10, cis ‐12 ‐ CLA in pure cultures, Weimer et al . () tested the effects of ruminal dosing of several strains of M. elsdenii but could not trigger a milk fat depression because the dosed strains did not establish itself in the rumen. Maia et al .…”

“…More specifically, Rico et al (2015) showed that the Butyrivibrio group decreases and M. elsdenii increases during induction of milk fat depression, with reverse changes observed during recovery. Because M. elsdenii has been shown to produce trans-10,cis-12-CLA in pure cultures, Weimer et al (2015) tested the effects of ruminal dosing of several strains of M. elsdenii but could not trigger a milk fat depression because the dosed strains did not establish itself in the rumen. Maia et al (2007) reported that the high abundance of this species with high starch and high oil diets probably links to its resistance to both low pH and UFA, but Palmonari et al (2010) observed that the link between milk fat depression and M. elsdenii abundance is independent on rumen pH.…”

Ruminal microorganism consideration and protein used in the metabolism of the ruminants: A review

“…Marx et al (2011), for example: Megasphaera elsdenii is a lactate-utilizing bacterium whose ruminal abundance has been shown to be greatly elevated during milk fat depression. Second Weimer et al (2015) studied the effects of the addition of M. elsdenii and concluded milk yield and composition were not affected by dosing. Ruminal pH, VFA and lactate did not differ between dosed and control cows, although acetate-to-propionate ratio declined in both groups and butyrate increased after dosing with M. elsdenii.…”