Alfalfa: A smart choice for dog and cat food?
Alfalfa is found in a number of cat and dog foods, but its safety and nutritional benefits are still being debated.
Alfalfa is found in a number of dog and cat foods. Perhaps this seems odd since we most often consider it a staple ingredient in livestock rations, especially dairy and beef cattle diets. For companion animals, alfalfa would ordinarily be encountered in horse diets and/or small rodent diets like those for rabbits, gerbils or guinea pigs. There are also some herbalists that promote its inclusion in human foods and supplements. However, the use of this forage in some dog and cat foods has created questions with consumers—specifically, whether alfalfa is an ingredient that belongs in these foods. Unfortunately, there isn't a compelling or definitive answer for the petfood company, veterinarian or pet owner.
Alfalfa (Medicago sativa), also known as Lucerne in some parts of the world, is a legume forage grown in temperate regions. The aerial portion is cut, dried in natural-gas-fired furnaces and then pelleted or it is cut, allowed to dry in the open (sun-dried or sun-cured) and then baled or stacked for later feeding. This perennial nitrogen-fixing legume grows continuously during the warmer months of summer and produces anywhere from three to five "cuttings" a year depending on the growing season, soil fertility and moisture.
Nutritionally, alfalfa (air-dried, ~10% moisture) will contain between 14% and 22% protein, ~10% ash, less than 5% crude fat and 15-30% crude fiber. Most of the fiber is insoluble and can be a natural source of gastrointestinal bulking. Relative to other vegetative ingredients used in petfoods, alfalfa is a rich source of calcium, potassium and other trace minerals. It carries a meaningful content of beta-carotene, vitamin K and various B vitamins. In addition, alfalfa contains chlorophyll which is often used as a natural food coloring (green) and the leaf extracts contain a host of other bio-active compounds such as saponins and phytoestrogens.
Most cultivated alfalfa is intended for dairy and beef cattle use as forage or roughage. In years past, it was also a source of feed for grazing pigs, especially gestating sows. It is commonly fed to horses, but requires some additional management oversight. In the agricultural academic literature there is a significant trail of information about the various values and nutritional aspects of feeding alfalfa to farm animals. The same is true for pet rabbits, gerbils and guinea pigs, where alfalfa is a staple in their commercial pelleted diets. But for dogs and cats, there isn't much information available; this creates a dilemma regarding its use and utility.
In dog and cat foods, one sees this ingredient alongside other "herbs" such as parsley, sage and rosemary, and/or as a vegetable alongside peas, carrots, potatoes, etc. It is purported to have a number of properties in these applications, from breath freshening and vitamin/mineral fortification to digestive aid and even promotion of urinary tract health in cats. While these might be admirable traits, there seems to be some confusion throughout the petfood supply chain as to whether alfalfa is truly beneficial. Pet owners are asking retailers, petfood companies and their veterinarians and getting mixed messages at best.
The big question is whether alfalfa is safe or toxic. To the negative, the "Cornell Book of Cats" lists alfalfa as a plant to be avoided because it contains saponic glycosides that are a putative intestinal irritant leading to nausea and vomiting, abdominal pain and diarrhea. Alfalfa and a number of other plants that do contain saponins are commonly included in pet diets (e.g., Yucca schidigera). However, there is not any case report evidence easily found in the literature to support that alfalfa is a gastrointestinal irritant. It has also been claimed to contain cyanogenic glycosides; but again, there is no evidence that this is an issue in a processed dog or cat food.
In addition, alfalfa is claimed to be a diuretic by one source and an "alkalizing" agent by another. How it came to be known as a diuretic was not explained, but its influence on urine or metabolic pH could be due to its known concentrations of oxalate. Alfalfa contains some 20-30% of its calcium bound as calcium oxalate (Ward et al., 1979), which would diminish the calcium bioavailability and thus might preclude its use in a feline oxalate stone dissolution diet.
To the positive, there are some studies in dogs and cats that would suggest feeding alfalfa is reasonably safe. For example, during the early days of vitamin application research, dogs were fed corn, soybean meal and alfalfa (5% of diet) diets for extended periods (six months) without issue (Campbell and Phillips, 1952). More recently, Fekete et al. (2004) fed alfalfa as a source of fiber for dietary energy reduction in cat foods. While they noted diminished palatability and digestibility of diets containing 10% alfalfa when compared to a standard like beet pulp, it did not appear to have any negative influence on health or wellness of the cats eating the diets.
The alfalfa ingredient that we receive and use in petfood applications is typically a 1/4 in. to 3/8 in. "dehy alfalfa" pellet. At the manufacturing plant, these pellets are ground and then mixed into the dry portion of the petfood or pre-blended with other vegetables, fruits and herbs into a premix. The addition rate is typically low, from 0.1% to 5%, depending upon the claims being made and the desired impact.
The ingredient is defined and accepted by most regulatory bodies around the globe for use in animal feeds and petfoods and is considered safe for modest inclusions in dog and cat foods. Whether there are negative health effects from its consumption by dogs and cats has not been adequately demonstrated; but to the converse, there is not a real compelling nutritional or functional reason why one would include it in the diet either. So, in the end, it depends on whether the pet owner wants this ingredient to fulfill some perceived need. For the rest, it likely does no harm.