Recently Nhan et at (2000) reported that farmers in Vietnam
A number of oils, those having anti protozoal activity have been demonstrated, amongst which the toxicity to protozoa appears to be the greatest with coconut oil. The dependence on ruminant livestock on low digestibility forages that are also heavily imbalanced with minerals and are low in protein suggests that the first step in increasing productivity is to achieve an efficient digestive system in the animal by strategic supplementation with molasses urea mixes. Once the rumen is balanced for microbial growth, the next step is to improve rumen outflow of protein to manipulate the protozoal populations to obtain maximum amount of bacterial protein from the rumen digestion of forage. The third step is then to feed additional bypass protein. The present program was undertaken with the objectives to improve productivity of ruminants by oil- defaunation and to determine the effective method of oil application for defaunation.
For studying the effects of oil and level of rumen protozoa, three cannulated bulls were used in the initial studies to assess the effectiveness of a number of oils to defaunate the rumen. The bulls weighed about 350kg live weight and were fed a diet composed of rice straw, cut and carry pasture and they were given a concentrate supplement at a rate of l kg twice daily at Ham and 5 pm. This diet supported a protozoal population of the order of 2-5 x 10-' /ml of rumen fluid A series of experiments were carried out with these bulls to test the effects of different oils and their levels on protozoal numbers in the rumen. All these experiments followed a similar pattern for the collection of rumen fluid sample and counting of protozoa. The bulls were fed at 9 am and rumen fluid samples taken before the oil was introduced and then at intervals of either hours or days. The rumen fluid was sampled by aspiration of rumen contents. Rumen fluid samples (5 ml) in duplicate were transferred to containers containing 1 in] of normal saline [(0.9% (w/w) NaCl and 10% (w/w) formaldehyde]. The protozoa were counted immediately under 10 times magnification by the usual methods. A minimum of 20 individual counts was recorded for each of the duplicate samples and means used to calculate the level of protozoa in the rumen.
