Llamas eating leaves

This post is a response to the question from the Rocky Mountain Llama and Alpaca Association. My llamas love eating leaves! Is there any nutritional value in the leaves once they fall? Along the same lines, I have heard that some leaves (specifically Shrub Oak) can be poisonous when they first come out in the spring…is there any truth to that?

Camelids are intermediate feeders sometimes consuming leaves both off the trees and those that fall during autumn months. Moreover, with the regenerative agriculture movement, there has been a resurgence of silvopastures. Silvopastures are the practice of integration of trees on grazing pasture lands. Producers looking to replicate nature has led to interest in incorporating more plant species diversity on the landscape including trees. With that, livestock consumption of leaves is on the rise. Llamas and alpacas specifically consume more tree leaves unintentionally due to their browsing behavior along with grazing. Leaves can provide a good source of protein, energy and micronutrients, but there are precautions that llama and alpaca owners should be aware of.

Tree fodder

In scouring the internet, you will find an abundance of pictures of llamas and alpacas eating leaves. However, there is certainly a deficit of research on the nutritional value and impacts leaves can have on camelid health and overall nutrition. Fortunately, with the resurgence of silvopastures, regenerative agricultural practices, and research into alternative forage sources when grasslands and other forage sources are scare due to increased droughts, there has also been an increased interest in studying leaves as a source of nutrition for grazing livestock. Most of these studies and resources refer to the leaf materials as tree fodder.

Tree fodder differs from typical forages and browses in two specific ways. First, forage is specifically cultivated and sometimes harvested for animal consumption. Second, browse is opportunistically consumed by intermediate and browsing animals including sheep, goats, llamas, and alpacas and typically consists of woody shrubs. Tree fodder is leaf materials that offer both nutritional value but comes from trees which were not specifically or opportunistically utilized by grazing or browsing livestock.

Nutritional value

The nutritional value of leaves has not been as widely studied as typical feeds and forages like legume and grass. But there are some resources that have recently become available. The first, is a study from the United States Department of Agriculture’s (USDA) Sustainable Agriculture Research and Education (SARE) : Quantifying Nutritional Value and Best Practices for Woody Fodder Management in Ruminant Grazing Systems. This project pulled leaves from six different species of trees every 2-3 weeks and analyzed protein, fibers, and micronutrients over time. Their study concluded that unlike common forage species, timing of consumption wasn’t important because the nutrients did not significantly change over time.

Protein

Table 1 summarizes the results from the SARE study highlighting that leaf fodder from four of the six species was a better source of protein than average grass pasture and was comparable to legume pastures. The other two species were still comparable to grass pastures in protein content. When we look at Camelid’s protein requirement it ranges from 8-16% depending on the physiological state. If leaf fodder were a main feed in the diet, very little protein supplementation would be needed.

Energy

Fiber content was very similar to legume pasture and much lower than average grass pasture. Energy values were not calculated. The equation for calculation is likely a place where more research would be needed to establish a reliable equation based on fibers. However, since the fiber content is similar to legume species, we can speculate that leaf fodder would be likely to exceed energy requirements for camelids at maintenance and meet requirements for more energy demanding states such as gestation, lactation and growth. However, this study mentioned the variability of all nutrients many times. So, observing animals’ body condition would be crucial. With llamas and alpacas specifically, we need to get our hands under their wool and feel their body to ensure they aren’t losing condition or gaining too much either!

Micronutrients

Turning our attention to the micronutrients supplied by leaf fodder, this study showed that leaves are an excellent source of minerals! All minerals analyzed were found in greater concentrations on average than common forage average except for phosphorous. However, this does not mean that feeding leaf fodder precludes the need for mineral supplementation.

Unfortunately, there is a lack of information related to llama and alpaca mineral requirements and maximum tolerable levels in the diet. But we can extrapolate with copper for example, domestic ruminant species require a minimum of 10 ppm copper in their diet, yet sheep are highly sensitive and should not be fed a diet with more than 15 ppm copper. So, pseudo-ruminants like llamas and alpacas, should be kept on a diet with a minimum of 10 ppm copper. So, although leaf fodder has more copper than most forages, it still requires supplementation to meet requirements and ensure healthy llamas and alpacas.

Potentially beneficial properties and anti-nutritional properties

In addition to the SARE project examining 6 leaf fodder species, there was a review of literature examining the potential for mulberry leaves to be used as an alternative forage and to perhaps improve production in ruminant species. Like the variability of the leaf species in the SARE project, protein in the mulberry leaves ranged from 14-34%, ADF ranged from 10-32% and NDF ranged from 19-49%. Along with the high protein, energy and micronutrient content of leaves, mulberry leaves specifically have flavonoids with the potential to act as antioxidants. There is potential that inclusion of mulberry leaves in milk cow diets can reduce oxidative stress in the rumen and increase digestibility and increase milk production.

However, mulberry leaves also contain several anti-nutritional factors that are not necessarily toxic but can have negative effects on animal health and production. Oxalates have been shown to reduce feed intake and also calcium bioavailability. Tannins can bind to protein and reduce degradability. This can be negative when feeding a diet specifically tailored to exactly meet protein requirements. But, in the case of grazing legumes, tannins are very useful in preventing bloat. Furthermore, some leaves can contain iminosugar alkaloids which inhibit glucosidase enzymes. Glucosidase enzymes are responsible for breaking down carbohydrates and providing the animals with energy.

Precautions

Oak Toxicosis

It is key if allowing llamas and alpacas to consume leaf materials whether as a purposeful addition to the diet or just because they have access to be aware of what species of tree leaves, they have access to. Oak tree leaves and acorns can result in illness and death if consumed by llamas and alpacas. According to Merck Veterinary Manual, “The toxic principle, which appears to be pyrogallol, gallotannins, polyhydroxyphenolic compounds, or their metabolites produced by microbial hydrolysis in the rumen; binds and precipitates proteins by astringent action, which results in GI, hepatic, and renal dysfunction.”

Symptoms typically do not start for 3-7 days after consumption. Symptoms include depressed, lethargic animals exhibiting gastroenteritis, going off feed, sudden anorexia. Ultimately, renal failure and death may occur. Call your vet immediately if you suspect oak toxicosis. Initial therapy should focus on rehydration and restoring electrolyte imbalances.

Cyanide Poisoning

Cyanide poisoning is also referred to as prussic acid poisoning. This occurs when animals graze plants containing cyanogenic glucosidase. These enzymes hydrolyze a compound called dhurrin into cyanide (HCN). Under normal conditions, plant membranes separate dhurrin from the cyanogenic glucosidase. Monogastric animals and hindgut fermenters such as swine and horses typically do not have an issue with prussic acid poisoning. Because stomach acid deactivates the enzyme.

However, ruminants and pseudo-ruminants are more susceptible to prussic acid poisoning due to the chewing of their cud. As those animals ruminate, the cell membranes are damaged. This allows the enzyme access to dhurrin, thereby releasing HCN into the rumen. The HCN is then absorbed directly into the bloodstream where it binds with hemoglobin. The bound hemoglobin cannot transfer oxygen to individual cells and death by asphyxiation is the result.

Again, this is only present in specific plant species. Most commonly this is a livestock health risk for grazing sorghum, sudan, Johnson grasses and hybrids. However, there are several trees that have dhurrin and cyanogenic glucosidase in their leaves. Do not allow llamas and alpacas to consume leaves from apricot, peach, choke cherry, pin cherry, wild black cherry, nectarine, almond or bird cherry trees.