Bentonite in a diet for ruminants increase the flow of both dietary and microbial protein to the intestines. It improves the protein to energy ratio in the nutrients absorbed.

Bentonite apparently effects the increase in protein nutrition by modifying the activity of protozoa by interfering with their mobility.

Bentonite improved performance of supplements to improve rumen function and to supply by-pass proteins

Bentonite – optimising the microbial mix in the rumen
Emeritus Prof. R A Leng, from the University of New England.

The rumen ecosystem consists of a consortium of organisms, the composition of which is controlled largely by the diet but with effect brought about by the animal’s own secretions in the rumen. It appears abundantly clear that the animal’s effects are largely mediated via the salivary flow adjusting the medium to a neutral solution. However, antibodies are secreted in the saliva and effect all populations of microbes and it is now feasible to immunise an animal against the many hundreds of strains of bacteria, bacteriophages and protozoa present in the rumen.

Research at the University of New England, first established that protozoa could be detrimental to the rumen, decreasing the protein that becomes available for digestion by the animal. Protozoa decrease bacterial protein outflow to the intestine, since they consume them in the rumen. But they also decrease any likely plant protein to escape fermentative digestion by again ingesting insoluble protein particles. The bacteria that are ingested by the protozoa are those that have detached from plant particles and therefore are ready to be washed from the rumen providing the animals with their protein supply. Protozoa accumulate in varying population sizes but when the animal is relieved for these, then the protein entering the intestine increases by about 25%.

The first demonstration of this phenomena was made at the University of New England when wool growth in penned or grazing sheep was higher by around 1kg annually in sheep without protozoa in their rumen compared with those with a normal rumen flora and fauna. However, the fact that the increase in protein to the intestines is increased by around the same value for a 10-fold variation in protozoal numbers suggests that protozoa harvest bacteria according to the population density in the fluid in the rumen. This means that a small population of protozoa can be just as devastation in lowering protein flow tot he intestines as a large population.

Considerable high cost, high technology research is now aimed at developing a vaccine against protozoa. However, again, observation in my own laboratory at UNE has pointed to a low-technology solution to the effects of protozoa in the rumen. Bentonite (Sodium) a clay mineral which wen manufactured to a refined powder has great capacity to absorb water and expand. A small quantity has an enormous surface area and also binds numerous minerals and ammonia. On the other, the surface area appears to adversely effect protozoa when it is present in the rumen increasing the protein that reaches the intestines and improving protein nutrition of the animal as indicated by both increases in growth rates of cattle and improved wool growth in sheep.

The most favoured concept is that a small amount of Bentonite in the diet reduces the capacity of protozoa to actively gather and consume bacteria allowing higher populations to remain in the fluid which is eventually washed from the rumen. The suggestion is that the fine particles gum up the swimming mechanisms of the protozoa.

Bentonite can be fed in a number of ways, but Australia has a world first in the development of Bentonite block aimed at increasing protein supply.

In studies again in UNE, with sheep supplemented to give high ammonia levels in the rumen with balanced minerals and without protozoa in the rumen, it was found that microbial growth efficiency approached 100% of the theoretical optimum for anaerobic systems. Feeding just 15g of Bentonite a day has produced about 75% of the response that removing protozoa and maintaining animal’s free of them achieves.

Provisions of bentonite will benefit ruminants increasing productivity on green pastures or pastures in any stage of growth or senescence, provided the rumen has been given a complete array of nutrients. It also decreases the maximum of bypass protein on dry feed needed to gain optimal response.

Ruminants have been observed to lick dry soils in many parts of the world. This has been attributed to minerals in the soil-licks but the correlation of minerals present in such soil and deficiencies in the animal are not convincing. As soil-licking is seen in all seasons but mostly in dry seasons, it seems that the animal may recognise the benefits of clays that have no content of nutrients on the protozoa and indirectly on the protein supply of the animal.