Practical Application of Defaunation of Cattle on Farms in Vietnam: Response of Young Cattle Fed Rice Straw and Grass to a Single Drench of Groundnut Oil

Farmers in the centre of Vietnam have a tradition of dosing young cattle with groundnut oil before fattening them on a diet of rice straw and road-side grass. These farmers claim the cattle grow faster. It was hypothesized that the effect of the oil could be to eliminate the protozoa from the rumen. This is known to increase the net microbial growth efficiency in the rumen and increase the protein supply to the animal. To test this hypothesis, two experiments were undertaken; one on-station with four cattle fitted with rumen cannulae and the second a growth trial with 25 young cattle in smallholder farms. When the cannulated animals were drenched with groundnut oil, the protozoa were eliminated from the rumen and animals could be kept free of protozoa by isolation. The ammonia concentration in the rumen fluid was decreased when the protozoa were eliminated and there was an indication of improved rumen dry matter degradability of the forage components of the diet. In the practical condition on the smallholder farms, the growth rates of cattle drenched with groundnut oil were increased considerably (65%) compared with untreated control animals. The laboratory results when taken together with the on-farm results indicate that these resource-poor farmers had been able to defaunate their cattle and to maintain the fauna-free state by isolation of their animals from extraneous stock. This traditional practice in Central Vietnam, whereby one family keeps only one or two animals that are hand fed and tethered, has quite a large potential for all of those countries where animals are fed agro-industrial by-products, as it is highly economic. The use of 1 litre of oil compared with 1 kg of rice polishing per day (300 kg over 300 days), would be highly profitable in all countries of South-East Asia.