Many caretakers regularly supplement their llamas diet with grains, typically rolled oats and/or cracked corn. Among grains, corn is arguably the riskiest of them all, but there are many factors to consider. For starters, we need to remember that llamas have a unique digestive system and are adapted to sparse grasslands. Grains are not a normal part of their diet. Grains as a concentrated energy source do have a couple of advantages. Cost per unit of energy is usually lower with grains than hay. It takes up less space (potentially useful as an on-the-trail supplement with pack llamas). It can provide supplemental intake to allow lactating females to reach their full genetic potential for milk production. Otherwise, grains are not normally needed. Typically good grass with a vitamin + mineral supplement tailored to your area and free choice granulated salt is all that is required.
On the downside, grains can be fatal. Acidosis and enterotoxemia are both deadly and are due to grain intake. The incidence of enterotoxemia can be reduced (but not eliminated) by vaccination against clostridium perfringins, types C and D (see below**). This common bacteria can bloom to toxic levels when grain is processed through the digestive system. Acidosis is a lowered pH of the rumen and is very difficult to monitor. Some individuals are more susceptible than others, so judging when the line has been crossed is extremely difficult. Both are very difficult to detect. Often the first noticeable symptom of enterotoxemia is death. Acidosis can come on more gradually, but again it can easily go unnoticed until it's too late. Soft feces instead of the normal dry pellets, absent of other causes such as parasites, is a sign of acidosis, particularly if impaired digestion (undigested fiber) is evident. Fecal odor changes from the shift in flora balance, typically becoming more pungent. There may even be small gas bubbles in the fecal matter.
Concentrated carbohydrates and starches will lower the pH of the rumen, shifting the balance of flora in the rumen and promoting tissue ulceration. Rumination of grains produces volatile fatty acids (VFAs), lactic acid, acetic acid, butyric acid, and propionic acid. Lactic acid, which is 10X stronger than acetic acid (found in vinegar -- vinegar has a pH of 2.5) is the worst offender. Whether or not pH lowers to dangerous levels is mostly a matter of quantity and rate of ingestion relative to buffering agents. Buffering agents include long fiber, phosphates and bicarbonates in the rumen. Exacerbating the acidosis, increases in VFA production reduces rumen motility, decreasing rumination and reducing saliva production, reducing the bicarbonate production.
A rumen pH below 6 is dangerous (normal ranges from 6 to 7 on a varied diet). When pH lowers below about 5.5, the microbial population shifts from mostly lactic acid users to mostly lactic acid producers, and an unrecoverable runaway condition occurs as the lactic acid users can no longer live and reproduce. Protozoa and fungi die off. Thiamine production drops precipitously, leading to polioencephalomalacia and general laminitis. Serious chemical damage to the stomach and intestinal lining also occurs below pH 5.5, impairing digestion and promoting ulceration. Liver abcessation can occur as well. After ingesting a sizeable quantity of grains, pH typically bottoms out 2-4 hours after consumption. If it doesn't drop too low, pH will gradually recover to normal.
If grain is needed in the diet, which is the exception rather than the rule, there are things that can be done to reduce the risk of acidosis. The form of the grain matters. The faster the digestibility the greater the spike in acidosis. Consequently, whole grains are better. Cracked/rolled/ground grains are riskier. Llamas have efficient digestive systems and grinding is not usually needed for good digestion. What happens is that whole grains are digested moreso in the intestine rather than almost entirely broken down in the stomach. This places the intestines at slightly increased risk of damage, but the risk to the stomach is much higher with quickly digested grains. Mucous in the stool is indicative of intestinal damage (mucous is excreted to protect the intestinal wall), but stomach damage has no apparent signs. By the way, corn contains oleic acid (2%) and linoleic acid (0.5%), both fats go rancid quickly once ground, which reduces nutritional value and tastes bad.
Pelletized (processed) grain products digest very rapidly.
Of course the amount of grain matters, but more importantly, the percentage of grain to long fiber is the most important aspect. Grain should never be given on an empty stomach. This means the time of day should be considered. Don't give grain in the morning. Wait until they have foraged on grass pasture or hay. The more they have to chew (within reason), the better. Beet pulp and similar sources of short fiber are nowhere near as effective as grass. Clover and alfalfa are also not very effective buffers. Chewing cud produces lots of saliva, which is rich in bicarbonate (pH of 8), which buffers the rumen to help keep pH neutral. Little chewing means little saliva, which means increased sensitivity to grain overload. The rate of grain ingestion matters greatly. Spread out over time more grain can be ingested without ill effects. Eaten all at once, damage can occur.
Health of the rumen flora population prior to grain ingestion affects sensitivity to acidosis and enterotoxemia. Lack of adequate water, i.e., dehydration, also promotes acidosis.
As for one grain vs. another, it's helpful to compare basic nutritive content.
As you can see, there are significant differences. Corn is almost entirely carbohydrates (sugars, starches), making it the most effective at promoting acidosis. These carbohydrates are digested rapidly and provide quick energy. Unless your llamas are working hard, this is generally undesirable. Pasture potatoes convert it to fat. Oat, on the other hand, is much lower in carbohydrates and higher in protein and fats. This is better than corn for underweight animals to put on body mass. It is also better for parasite resistance. Studies have shown that high protein diets vs. high carbohydrate diets help somewhat in reducing parasite load. Be aware that rye can contain endotoxins that are harmful to llamas.
The shift in the flora balance in the digestive system is not limited to those related to acid production. Also worth noting is the sharp increase in E. Coli associated with grain digestion. E. Coli is an acid tolerant bacteria. This is why sickness in humans from E.Coli contamination of hamburger, vegetables, etc., didn't exist decades ago prior to the practice of grain finishing of beef cattle. Small amounts of grain will not result in significant E. Coli levels.
**Clostridium perfringens is a bacterial pathogen that is categorized into
five different genotypes, A through E. CDT only vaccinates against types C and
D, and the combination of the two provides limited protection against type B.
At issue is that symptomatic infection of types C or D is uncommon in llamas.
They apparently just aren't very susceptible to it. More often when it occurs
it is type A, which CDT or Covexin 8-way provides no protection against.
Another note regarding immunization: CDT should not be given to a cria. Vaccines are meant to stimulate antibody production. Crias get their initial bank of antibodies from the mother via colostrum and have no functional immune system of their own to stimulate. Consequently vaccination is of no value and reportedly it actually depletes the antibody bank received in the colostrom, putting the cria/youngster at greater risk of succumbing to illness prior to immune system maturity.