5 guidelines for alternative animal feed ingredients
Whether it is rye or copra meal, using a non-conventional ingredient requires attention to certain issues common to all alternative options. Photo: Leonardo255, Dreamstime
“There is nothing better for pigs than a corn- and soybean meal-based diet.” This is what my professors told us at Kansas State University and University of Illinois, and they were right! I am sure many nutritionists in Europe would have said the same thing regarding a wheat and soybean diet. But who ever asked birds or pigs what they really like when cereal and soybean prices are not in their favor?
In such instances, the so-called alternative and hence less expensive ingredients enter feed formulas in an effort to keep feed cost down; after all, profitability is as predictable as the weather, which for many farmers means better feed low now than anticipate high pork prices later. This is when we nutritionists get to justify our fees, because all these alternative ingredients come with many problems that go along with their lower price.
I have written many articles explaining in detail how to incorporate many cereals (wheat, barley, sorghum) and protein sources (corn gluten, rapeseed meal, sunflower meal) in pig and poultry diets, based on my consulting experiences throughout the world. Through this exercise I have identified several common issues when it comes to feeding these less conventional feed ingredients. These I describe below:
1. Variability in nutrient concentration
Corn has about 8.1 percent crude protein with a very low variability (Standand Deviation, SD 0.7 percent). In contrast, potatoes (dried) have about the same amount of crude protein (8.8 percent), but double the variability (SD 1.3 percent). In practical terms, this means 95 percent of all corn samples are expected to be between 8.1±2×0.7 (6.7 to 9.5 percent) in crude protein, a range of 2.8 percent points. Potatoes, however, will be between 6.2 and 11.4 percent in crude protein, a range of 5.2 percent points.
Although these two ingredients appear to be comparable in crude protein, their different degree of variability means that when potatoes replace corn, the resulting formula will be less precise, assuming of course one uses table average values. More variable feeds result in more variable animal performance, which either way of the equation is lost profitability or wasted money. The reason why alternative ingredients tend to be more variable not only in crude protein but also in energy and all other nutrients is because corn and soybean genetics are rather standardized around the world. Plus, many agroindustrial by-products are highly variable as no two plants follow the exact same procedure or use the exact same raw material. The solution to this problem requires frequent chemical laboratory analyses or a robust near-infrared (NIR) system, or accounting for variability through more sophisticated feed formulation programs. In both cases, there is an extra expenditure that must be added on the price of any alternative ingredient. If not, any alternative ingredient is likely to fail or be more expensive than the more conventional ingredient that it tries to replace.
2. Many new anti-nutritional factors
Corn is rather benign, and soybean meal is well tolerated by all species, save the youngest animals. When it comes to alternative energy and protein sources, there are few ingredients as innocent as these two staple feeds. Rice and sunflower come to mind, but the first is seldom inexpensive to use in animal feeds, whereas the second is almost always full of undesirable crude fiber. Most alternative ingredients come with a plethora of anti-nutritional factors that will cause serious trouble if left unattended. For example, bitter components in sorghum (tannins) that act as a deterrent against birds in the wild also cause significant drop in animal performance when used in excessive amounts.
Most alternative ingredients come with a plethora of anti-nutritional factors that will cause serious trouble if left unattended.
Another example is that of cottonseed meal that contains a pigment (gossypol) that can turn egg yolk a greenish hue. Of course, there are solutions to each and every problem, but one must be aware of these issues beforehand. Plus, the cost to counteract these antinutritional factors must be incorporated into the ingredient cost. Sometimes this is negligible, others it is prohibitive.
3. Inclusion level recommendations can be deceptive
There is a great number of research reports in which each alternative ingredient has been tested against the target ingredient that it can replace. Thus, fava beans, for example, are a good source of protein, but like all legumes they contain more than enough antinutritional factors. In this case, there are tannins, lectins, trypsin inhibitor activity compounds and glucosides, not to mention very hard to break fibers. As such, many reports that have tested fava beans might point to finding the maximum safe inclusion level. Such a study would have been conducted using a corn (or wheat) and soybean meal based diet as the control. Under this scenario, animals can tolerate a maximum, say, of 10 percent fava beans without loss of performance or health. Such maximum inclusion levels are available for all alternative ingredients. For example, rapeseed meal can be used up to 20 percent in a specific diet, whereas corn gluten meal up to 15 percent. But it is currently unknown if these maximum values can be used in a diet that contains more than one alternative ingredient.
Is it possible, for example, to have a diet with 10 percent fava beans (the maximum inclusion level), 20 percent rapeseed meal and 15 percent corn gluten meal? Perhaps for some classes of animals (breeders?) this might be acceptable, but younger animals might have trouble coping with an influx of antinutritional factors. Until we have more research on this less appreciated aspect of alternative ingredients, one is advised to follow a conservative approach and either limit inclusion levels well below maximum recommendations or limit the number of alternative ingredients in each formula. Without providing any solid or scientific evidence, it is interesting to note that most formulas from the Netherlands (where they use a vast array of alternative ingredients as the norm) contain but miniscule amounts of each such ingredient, often no more than 5 percent.
4. Contaminants are the major cause of rejection
Contaminants are not just the mycotoxins, although these have received the majority of publicity. Even soybean meal contains an insignificant amount of a solvent used in the extraction of oil, and this is tightly controlled. Many other protein sources that are virtually by-products of the oil industry might contain undesirable chemicals. And contaminants do not always have to be hazardous. Fish meal, albeit more expensive than soybeans, contains sand that can reach alarming levels.
It is also not unheard for certain plants to use their flow of by-products as a convenient means of general waste disposal. I have personally witnessed the presence of general garbage (plastic bags, ropes, etc.) in a batch of alternative (and hence less expensive) milk replacer powder. Of course, it is infrequent, but it also happens for certain toxic materials to find their way, most likely inadvertently, into feed materials — dioxins come to mind, or fertilizer nitrogen into meat and bone meal. Some times, the issue of unavoidable contaminants is just a case of controlling their levels, but one must be aware of their potential presence. In other cases, and these are the most hazardous, it is impossible to predict their presence.
5. Handling and storage can be different
If molasses is deemed beneficial as an alternative energy source, a surprise will greet its potential users in cold weather. It will simply not flow! Molasses needs heating, not to mention a special container, transport and mixing system. The same can be said for many more ingredients. Take wheat, for example. Those who are used to feeding corn may find the occasional truckload of wheat inexpensive enough to entice them to give it a try. If wheat is ground at the same degree of fineness as most corn batches are ground, then it will bridge into silos and feeders, stick to the beaks of birds, make pellets harder and even increase gastric ulcer incidences in stressed-out pigs. Thus, wheat needs to be ground a bit coarser than corn. These two examples serve to illustrate that the physical properties of each ingredient must be considered beforehand, as there are no guarantees they will perform like the ingredients they are going to replace.
Alternative ingredients are a great means of controlling feed cost. In fact, animals can tolerate a great deal of “exotic” ingredients. Even though the feed conversion index might be worse, alternative ingredients can provide enough incentive to cope with their problems. This latter is a number of issues, all quite unique to each different ingredient, that must be considered well in advance. The cost of addressing these issues should always be added on top of the buy price for each non-conventional ingredient.
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