Distillers dried grains with solubles (DDGS) is produced as a by-product of ethanol production. After fermentation of a grain source, the wet mash and a portion of syrup (solubles) are mixed together and a dried product produced. Under traditional dry-grind processes, the protein, fat, and minerals of the fermented grain are concentrated by a factor of three and contain residual yeast. Sugars and starches should have been utilized in the fermentation process. The characteristics of the protein and fat reflect the original grain make-up. In the Midwest, DDGS is usually derived from corn and contains about 27% crude protein, 10% crude fat, and .75% phosphorus. The main use of DDGS in poultry diets is for partial replacement of some of the corn and soybean meal. DDGS also provides sufficient phosphorus to reduce the amount of mineral phosphorus supplement in the diet. Maximum usage levels are up to 20% of the diet with well characterized products and nutrient adjustments.
In chicken egg layer diets as summarized by Batal and Bregendahl (2012), DDGS has been incorporated into diets without a reduction in reproductive performance. Earlier work with product produced from the alcohol beverage industry, up to 20% could be included often with benefits in Haugh units (measure of albumen quality). More recent work indicated that up to 10-15% ethanol derived DDGs could be included in chicken layer diets when the diets are formulated on a digestible amino acid basis and adjustments made to maintain diet energy. One study indicated that inclusion of 15% DDGS in a lower energy density diet tended to decrease egg production, while another noted decreased egg weight when included at 20-25%. The results of the latter trial were suggested to be due to an amino acid deficiency while the former, was thought be due to lower intakes of nutrients as feed intake was not increased when the energy level was decreased. The studies indicate that inclusion of DDGS are possible in chicken egg layers diets in the range of 10-15% while higher levels might be possible with appropriate adjustment of diet energy levels. Studies on breeder reproductive performance when fed DDGS are not widely available. Manley et al. (1977) showed no effect when including a low level, 3% DDGs, in turkey breeder diets. Jensen et al. (1974) with Leghorn hens showed no effect by the addition of 5% DDGs to wheat-based diets on egg production, fertility and hatchability. At 10% DDGS, additional supplemental lysine was needed to restore egg production to the 5% level. Based on personal communication, DDGS has been used in broiler breeder diets without problems.
While the research on inclusion of DDGS might be extended to other types of birds such as pheasants, feedback on the use of DDGS in breeder pheasant feeds have indicated problems such as decreased egg production, decreased fertility, and increased mortality and health problems in the progeny. The remainder of this paper will explore why these performance differences may exist relative to nutrient composition of the DDGS and the need for nutrients in pheasant reproduction.
Unfortunately, there is little published information on nutrient requirements for pheasants – growing and breeding (NRC, 1994; Leeson and Summers, 2005). Hence, this paper will rely on research information for other types of poultry. In breeding poultry diets, diet composition and nutrient levels are critical both in supporting growth of the young breeder bird followed by development of sexual maturity and subsequent egg or sperm production. Growth the young breeder can influence latter breeder performance. As breeders, egg quality (internal and shell) must be good enough to support the initial development of the fertilized egg. Nutrient levels in breeder diets need to be sufficient enough to support the production of eggs as well as embryo growth; and, carry-over for hatching and post-hatch nutrition until the hatchling begins to eat. Deficiencies of vitamins and minerals are usually identified by specific egg quality or embryonic malformations causing decreased hatchability and/or early progeny mortality (Wilson, 1997) . Slight nutrient deficiencies are more difficult to detect and may not be discovered for some time.
Diet protein and energy can exert separate effects on reproductive performance or in relation to each other (Whitehead, 1987). Limitations of protein or specific amino acids such as lysine can affect egg production, egg weight, and fertility (Fisher and Gous, 2009). Metabolizable energy content of the diet influences feed intake and hence intake of other nutrients. If energy intake is reduced sufficiently through inadvertent feed restriction or if gut fill limits intake with inclusion of high fiber ingredients, the intake of energy and other nutrients will be limited. High fiber content of the diet can also limit nutrient absorption. At some point, intake of critical minerals and vitamins will be insufficient and hurt hatchability. Care also needs to be taken not to overfeed, as excess protein in relation to energy content has been shown to depress hatchability in broiler breeders. Likewise excess mineral or vitamin supplementation can affect absorption of other vitamins and/minerals. An example would be the decreased absorption of Vitamin D3 with high levels of Vitamin A (Kidd, 2009).
As mentioned previously, the primary fit for DDGS in the diet is to provide protein, energy (oil) and phosphorus. While DDGS can contribute some vitamins and other minerals, most of these will be provided as supplements to the feed. Some minerals that could cause problems, if excessive, would be sodium, chloride, and/or sulfur.
Regarding protein, the quality of the protein needs to be defined in a couple of ways. One is the amino acid composition. Corn protein in DDGS is limiting in lysine, arginine and tryptophan so attention should be paid to these amino acids when formulating the diets. Another aspect of protein quality is the digestibility of the amino acids. Because of the heating process, the lysine is partially damaged and can’t be digested. Diets should be formulated using digestible amino acid content. On average, true digestibility for lysine is 70% but some individual samples showed much lower digestibility.
The energy content of the DDGS also varies and is affected by the amount of syrup (solubles) added to the product or the amount of oil that is removed from the product during processing. For the more conventional product with 10-12% crude protein, and energy vale of 2800-2850 kcal/kg could be used. If oil has been removed, the energy value should be reduced.
If DDGS diets are formulated without consideration of digestible lysine content and energy content, most likely the amino acid levels and energy levels will be in deficit especially at higher levels of DDGS inclusion.
Provision of phosphorus in the diet represents an expense. The phosphorus content of DDGS is around .7% and can reduce the amount of dicalcium phosphorus used in the diet resulting in some cost savings. The phosphorus in DDGS also varies in its biological variability which means if the available phosphorus is underestimated, the diet could contain excess phosphorus. The excess of phosphorus could lead to eggshell quality issues by decreasing calcium absorption and affect hatchability. Another mineral to be concerned with sulfur. DDGs can contain .3 to 1% sulfur. High levels of sulfur in the diet can also interfere with calcium absorption leading to eggshell quality issues. Sulfur can also be contributed by other ingredients such as canola meal.
Besides variability in nutrient composition and the digestibility of the nutrients present; contaminants such as mycotoxins can be present. Mycotoxins on the corn are also concentrated 3-fold in DDGS as they are not destroyed during the fermentation and drying process. Several surveys of DDGS were conducted to determine mycotoxin content (Caupert et al. 2012). Depending on the survey, aflatoxin, deoxynivalenol, and fumonisins were detected but usually at low percentages and lower than the FDA regulation levels. Because the mycotoxin levels in corn will vary from year to year depending on harvest and storage conditions, corn harvest conditions should be monitored and loads of DDGS should be tested. Some labs such as Dairyland Laboratories will post their test results during the harvest season or your local extensions office might have up to date information. Mycotoxin binders can be used if approved products are available and have an affinity for the mycotoxin of concern.
Batal and Bregendahl also pointed out other characteristics of DDGS that may indirectly impact intake of DDGS containing diets which included nutrition variability, pellet quality, supplemental fat levels in the diet with DDGS use and bulk density of the product. To assure minimal change in feed consistency and nutrient variability, obtain material from one or two sources at most. If diets are being fed in pelleted form, inclusion of DDGS can decrease pellet quality depending of level of inclusion and amount of supplemental fat added to the diet. Bulk density of DDGS is less than that of corn and soybean and hence birds may fill up “quicker” and feed intake may be limited. Likewise, the type of corn co-product being used should be confirmed. Many ethanol plants are producing modified products such products with some of the oil removed; or products that are much higher in protein (42%) but contain significantly less fat (3%) and phosphorus (.4%).
In summary, use of DDGS in poultry diets requires good information regarding the nutritional value and quality. In particular if DDGS is going to be used, diets should be formulated on a digestible amino acid basis to meet the requirements of lysine, methionine and cystine, threonine, arginine and tryptophan. DDGS purchases should be limited to one or two sources and lots monitored for protein, fat and fiber, and presence of mycotoxins. The type of product being utilized should be confirmed. Where risk is high, DDGS use should be limited.
Batal, A. and K. Bregendahl, 2012. Feeding ethanol coproducts to poultry. In “Distillers Grains: Production, Properties, and Utilization. Ed. K. Liu and K. A. Rosentrater. CRC Press.
Caupert, J., Y. Zhang, P. Imerman, J. L. Richard, and G. C. Shurson. Mycotoxin occurrence in DDGS. In “Distillers Grains: Production, Properties, and Utilization. Ed. K. Liu and K. A. Rosentrater. CRC Press.
Fisher and Gous, 2009. Protein and amino acid responses. In “Biology of Breeding Poultry”. Ed. Paul Hocking. CAB International.
Kidd, M. T. 2009. Vitamins, Minerals, and Micronutrients. In “Biology of Breeding Poultry”. Ed. Paul Hocking. CAB International.
Leeson, S. and J. D. Summers, 2005. Commercial Poultry Production. 3rd ed. Guelph, ON; University Books.
Whitehead, C. C, 1987. Nutrition of turkey breeding stock. In “ Recent Advances in Turkey Science. Ed. C. Nixey and T. C. Grey. Poultry Science Symposium 21. Butterworths
Wilson, H., 1997. Effects of maternal nutrition on hatchability. Poultry Sci. 76:134-143.