Formulating poultry and pig diets with bakery meal
A well-known ingredient, bakery meal is not used as effectively as it can be, mostly because of lack of understanding on how to address its variable nutrient profile.
Bakery meal has many names in different parts of the world: dried bakery product, bakery waste, cookie meal, bread meal, biscuit meal, etc. Despite the many names, and variable composition, it always describes the same source of materials, namely byproducts or waste of the bakery industry consisting primarily of wheat flour and variable quantities of sugar, salt, oils and additives.
In general, bakery meal is rich in starch because wheat flour is the main ingredient in all bakery products. Because this starch is already thermally processed (cooked), it is highly digestible, and thus, of high nutritive value. As such, bakery meal is ideal for the diets of young pigs and starter broilers. In general, bakery meal contains about 2,981 kcal/kg net energy (NRC-Swine, 2012), which compares very favorably with maize at 2,672 Kcal/kg net energy. Accordingly, it contains 3,500 kcal/kg metabolizable energy for poultry, when maize is at 3,300 kcal/kg.
However, if candy bars, snacks, cakes and other high-fat ingredients comprise a large part of the product mix, then bakery meal will also be of high-fat concentration (normal levels are about 8 percent as for the above quoted energy level). Any extra fat will increase dietary energy and must be taken into account when formulating diets. In some instances, this extra energy content is diluted at the source by the addition of a flowing agent, such as soybean hulls and/or limestone.
Salt is almost invariably a part of any baked product. Some contain more than others, and therefore the salt (sodium) content of bakery meal must be monitored very closely. To this end, the inclusion level of bakery meal on any formula should not exceed what is needed to meet the sodium requirements of the animal. Removing other high-salt ingredients (such as fish meal or animal plasma) and, of course, pure salt, from formulas increases the upper limit of inclusion rate for bakery meal.
Sugar is usually quite high in most bakery products, and the final concentration in bakery meal can be as high as 20-25 percent. If such product is available, then the extra sugar added in the final diet must be taken into account in the case of young pigs. First, because excess sugar can lead to nutritional (non-pathological) diarrhea (soft or watery feces), and second, because sugar is a sound replacement for lactose.
Finally, the protein content of bakery meal, around 10-12 percent, is not of the best quality possible, and perhaps a part is destroyed due to overcooking. But, if high-protein ingredients were used in the bakery products, then the nutritive value of the protein in bakery meal can be of significant value.
High-quality bakery meal can be included in pig formulas without any restraints as long as the above issues of high-fat and high-sodium concentrations are taken into account.
For piglets, up to 30-40 percent is possible but rarely seen in commercial formulas, although such levels make the final diet very palatable. In older pigs, less is usually the norm, only because of availability and price concerns.
In general, it may be assumed that 1,000 kg of bakery meal is equivalent to 850 kg maize, 90 kg soybean meal (44 percent), and 60 kg fat/oil. This generic formula is a rapid method to identify potential cost savings when the prices of all ingredients are known and before a feed formulation program is employed for a finer analysis.
In poultry, an upper limit of 15 percent is often prescribed, if only to prevent loss of performance due to variability in nutrient content from batch to batch. Higher levels are possible if bakery meal of a known source and nutrient profile is used, always within the limits of sensitive dietary nutrient specifications (that is, sodium, fat, and protein quality).