Meadow plants reduce unwanted protozoa
Ruminants are notoriously inefficient when it comes to nitrogen utilisation. This has a knock-on effect on the environment because of nitrogen excretion in the urine and faeces. Consequently, there will also be a reduced protein content in livestock products, meat and milk. The extent to which the grazer will assimilate nitrogen from the food is partly dependent on the contents of its rumen. This first chamber in the alimentary canal is a seething mass of microbes, predominantly bacteria and single-cell animals, protozoa. This is a dynamic ecosystem in its own right and this delicate balance is inevitably affected by the diet of the animal. Scientists at the Rowett Research Institute in Scotland investigated the effects of the protozoan population on nitrogen retention in the rumen. They discovered that a reduction in the numbers of protozoa would increase the efficiency of nitrogen utilisation. This is due to the fact that these single cell marauders consume vast quantities of the bacterial fauna in the rumen. As the microbes digest and ferment the fodder, reduction in the population size of the bacteria can reduce the yield of protein from microbial action. Ironically, the team discovered that this can be remedied by administration of extracts of meadow plants in the livestock drinking water. These plants, once a natural feature of old grazing pastures, are all too often missing from modern intensive feeding regimes. They include the daisy (B. perennis), pussy willow with its furry flower structures (Salix caprea) and the stinging nettle Urtica diocia. It would perhaps be impractical to reintroduce the farming conditions prevalent prior to large-scale mechanisation. Indeed, certain meadow plants, for example groundsel, are toxic to ruminants. Careful management however, combined with biotechnological know-how, can yield a highly productive regime, with limited damage to the environment.