Ruminal acidosis: A review with special emphasis on the controlling agent Megasphaera elsdenii NCIMB 41125

Coping with ruminal acidosis in the high-yielding dairy cow – the success of the lactic acid utilizing organism Megasphaera elsdenii NCIMB 41125. The organism, further referred to as ME, is a South African invention; the results of the research with relevance to the dairy cow are reported in a number of scientific papers which have been reviewed by Meissner and co-workers in the paper: Ruminal acidosis: A review with special emphasis on the controlling agent Megasphaera elsdenii NCIMB 41125, published in 2010 in the South African Journal of Animal Science, Volume 40, pages 79 to 100.

The species to which the ME organism belongs occur naturally in the rumen and utilizes lactic acid as substrate. Lactic acid is produced when the feedlot animal or dairy cow is rapidly transferred from a high roughage diet to a high concentrate diet. The acid accumulates if the animal is not correctly adapted to the change in diet, simply because the organisms that produce lactic acid from starches and sugars which are the energy sources in concentrates, outweigh the lactic acid utilizers. ME was selected under stringent conditions and thrive on lactic acid and low rumen pH, which are the typical conditions conducive to ruminal acidosis (also called lactic acid acidosis). In practice ME is dosed at a level of 10⁸ to 10⁹ organisms per millilitre (ml) in a suspension of 30 to 200 ml depending on the size of the animal, to the animals before they are transferred to a high concentrate diet; by doing so, ruminal acidosis has been effectively controlled in feedlot cattle and sheep, in sheep that graze maize residue camps containing high proportions of maize kernels and in dairy cows.

Research on dairy cows has been done at the ARC – Irene, the University of Pretoria and at the Institute at Reading in the UK. The most significant findings are a general improvement in animal health with less incidence of metritis, abomasal displacement, retained foetal membranes, ketosis, milk fever and others. This is ascribed to the fact that during long term exposure of the cow to subclinical ruminal acidosis its immune system is compromised and therefore the cow is more susceptible to these conditions and diseases. A second advantage is higher feed intake with less daily variation in the first one to two weeks after calving, although this does not always occur, which obviously could assist in preventing ketosis, maintaining energy balance and increasing milk production. Whether milk production will be increased apparently depends on two issues: the level of production of the cow and the energy concentration of the diet. In the studies high yielding cows (producing 35 to 45 litre per day) benefitted with increased productions of 1 to 4 litre per day whereas cows producing less than 30 litre did not show a response. A milk production response was also evident when the concentrate level of the diet was of the order of 70% but not when it was of the order of 60% or less, which corresponds with the levels which are normally recommended. A 70% concentrate diet will cause more lactic acid in the rumen than a 60% concentrate diet and until now could not have been fed. However, such a diet is actually required to meet the energy requirements of the high yielding cow, and therefore the response in milk yield of such cows when ruminal acidosis is controlled. Bottom line: Dosing with ME will allow high yielding cows to reach their production potential, because diets with higher energy concentrations than generally recommended can be employed without the risk of exposure to subclinical ruminal acidosis.