Petfood manufacturers have for years been aggressively exploring the world for quality economical ingredients. More recently, companies have tried to find novel and unusual ingredients to attract pet owners' attention. But a new motivation may soon be pushing the introduction of novel ingredients--scarcity.
A number of staple petfood ingredients are becoming more difficult to purchase, in part because of:
- Competition within the industry fueled by growth;
- Competition with other industries such as aquaculture for similar ingredients;
- Regional droughts and shortages; and
- Decreasing waste in human food processing.
There are also growing concerns about pathogenic bacterial contamination, declines in quality with changes in the mix of by-products reaching rendering, an increase in cases of allergy and hypersensitivity to conventional ingredients and growing demand for antioxidant carotenoids and essential fatty acids.
Topping the list
At the top of the scarcity list are marine products: proteins and fatty acids. Growing human populations, increasing knowledge regarding fatty acid requirements and over-fishing are expected to put greater pressures on fisheries, with the expectation that fish stocks will soon be incapable of supporting demand. This affects people and their pets. So what can we do?
One emerging option to this dilemma is plankton. It might seem like a real stretch, right? Well, not quite as big a stretch as you might think. A number of plankton or "microalgae" are suitable for industrial exploitation. While still somewhat futuristic, efforts have been under way for more than 50 years to grow, harvest and evaluate scores of organisms for productivity, nutrient composition, safety, agro/aquacultural sustainability and economics.
Filling a niche
These varied species of plankton originate in large bodies of water such as the world's oceans and lakes.
By definition, they are floating or drifting organisms incapable of controlling their own motility or direction and fill an ecological niche rather than a phylogenic or taxonomic family. They are commonly referred to as phytoplankton, zooplankton and bacterioplankton.
These mostly unicellular organisms are at the ground floor of the ocean's food chain, supporting a broad diversity of organisms, and are the primary source of numerous essential nutrients (e.g., long-chain fatty acids) that accumulate with each successive trophic order of marine organisms. In other words, the omega-3 fatty acids in fish are derived from their diet, rather than their own synthesis, and these fatty acids are produced by plankton.
The more commercially viable plankton can be found in the families of green algae, cyanobacteria and protists. They have crazy sounding names, including such green algae organisms as Chlorella , Dunaliella and Haematococcus , cyanobacterium such as Arthrospira (Spirulina) and Aphanizomenon , dinoflagellates such as Crypthecodinium and chromista such as Shizochytrium .
Some of these organisms are photosynthetic, thus taking CO2, nitrogen and light and producing valuable carbon compounds such as simple sugars and amino acids. Others are heterotrophic organisms that utilize simple sugars and salts along with heat to produce more complex molecules such as carotenoids and long-chain fatty acids.
Plankton are composed of proteins, carbohydrates and fats that rival some terrestrial proteinsfor example, Spirulina can exceed 60% protein, 13% carbohydrate and 6% fat on a dry matter basis. Plankton proteins are nutritionally available, although somewhat lower in quality than casein or soy. This is most likely due to a slightly lower protein digestibility combined with a lower ratio of essential amino acids such as methionine and histidine.
A viable source for most essential water soluble vitamins, carotenoids and tocopherols (vitamin E), plankton are also reported to be a rich and nutritionally available source of iron, selenium and iodine, among other minerals. Plankton are reputed to possess numerous nutraceutical compounds and anti-inflammatory mediators. Generally speaking, plankton are safe for consumption but the amount in the diet may need to be limited. Under certain stressed growing conditions, though, toxic agents can be a concern.
While nutritional utilization of the plankton biomass may have been the original intent, today the principal consideration in the production of plankton is for harvest of specific nutrients. In other words, plankton are being farmed in ponds and grown in fermentation tanks for the production of specific molecules such as long-chain fatty acids. This is the application that holds the greatest near-term use for human foods and petfoods.
Limited but promising
Consumption of whole blue-green algae ( Spirulina ), beta-carotene extracts from Dunaliella and astaxanthin from Haematococcus are reported for human, livestock and marine diets. However, reports of this sort are not readily found for dogs or cats.
The long-chain fatty acid docosohexaenoic acid (DHA) extract derived from Crypthecodinium (a dinoflagellate protist) has been used in infant formulas. More recently, this same source of DHA has made its way into specialized pet diets. This application offers a targeted source of DHA devoid of eicosapentaenoic acid (EPA) common to fish oils.
More work needs to be done to determine how pets are affected by the various sources of plankton and how it might be effectively used to augment current supplies of critically limited nutrients from terrestrial sources. The controlled production of these organisms in ponds and fermentation vessels provides a deliberate and safe method to produce quality proteins, vitamins, antioxidant carotenoids and essential long-chain fatty acids.
The future of plankton (microalgae) products in pet diets has much untapped promise as a source of safe, quality sustainable biomass and supply of essential nutrients in a time of increasing scarcity.