The 2010 International Poultry Scientific Forum in Atlanta, Ga., included a number of presentations of interest to feed millers.
A presentation by scientists at Mississippi State University looked at the effects of varying levels of DDGS (distiller's dried grains with solubles) on pelleting characteristics and feed mill efficiency. The Mississippi State team evaluated diets formulated to contain either 15% or 30% DDGS, compared to a control diet devoid of the ingredient. Feed rate entering the conditioner was held at 1.2 metric tons per hour for a pelleting mill with a rated capacity of 0.9 metric tons per hour with a set temperature of 82.2C. Production rate was unaffected by the level of inclusion of DDGS in diets.
The 15% DDGS treatment reduced conditioner electrical energy use compared with the control diet and the 30% DDGS increased this parameter. The control feed showed a significantly greater relative energy use for the pelleted meal, compared to diets containing DDGS. Increasing levels of DDGS reduced structural integrity of pellets, as measured by pellet durability index. The 30% DDGS diet yielded the highest value for total fines. The researchers concluded that high levels of DDGS in diets reduce pellet quality but lowered the energy required for pelleting.
Feed performance studies conducted at Auburn University in conjunction with Kansas State University and the U.S. Department of Agriculture’s Agricultural Research Service laboratory at Mississippi State University compared broiler diets with a pellet durability index of 89% with lower quality pellets of 66%. A mash diet served as the control. Corn was ground using a roller mill.
The studies evaluated live performance and meat yield of broilers from 15 to 42 days of age. Broiler weight gain was approximately 4% higher in broilers fed pellets than in broilers fed mash. Pelleting of feed increased carcass weight by 107 grams and breast weight by 37 grams over broilers fed mash.
In another study, expeller-pressed soybean meal was compared with solvent-extracted meal at two different levels of granulation. Fine soybean meal was ground to 390 microns. The coarse meals were incorporated in feed with a particle size of 1,040 microns. Eight replicate pens holding 32 broilers each were used to evaluate the four treatments.
Fine-ground expeller soybean meal resulted in the lowest weight at 49 days (3,605 grams) compared to either coarse-ground solvent extracted soybean meal (3,794 grams), coarse-ground expeller soybean meal (3,803 grams) and fine-ground solvent extracted soybean meal (3,762 grams). The expeller soybean meals combined yielded an adjusted feed conversion ratio of 1.77 compared to 1.90 for the solvent-extracted soybean meals, suggesting that the estimated metabolizable energy value of 2,800 kilocalories per kilogram was in fact too low, despite the calculation based on analyzed moisture, protein and fat composition of the ingredient.
A controlled trial at North Carolina State University evaluated the accuracy of post-pellet application of fat in broilers through 42 days of age. Fat was applied at 80%, 100% or 120% of target level and compared to a diet in which fat was added into the mixer. Assays of diets showed correspondence with the targeted addition levels of fat applied to pellets. There were no differences among treatments with respect to body weight of broilers fed the diets. Increasing the level of fat addition improved feed conversion efficiency with values ranging from 1.78 for the 80% addition rate to 1.75 for the 120% rate.
Broilers receiving diets in which fat was added into the mixer yielded a feed conversion of 1.80. There was only a small numerical (non-significant) difference in feed conversion efficiency between diets with under-application of fat.