Buhler, Inc. of Minneapolis, Minnesota has developed a new fractionation process to more efficiently produce ethanol from corn. In this process, the germ is removed from the corn grain and the degermed grain is passed through roller mills and aspirators to remove the bran. The endosperm is fermented to produce ethanol, and the rest of the grain is left as a co-product, referred to here as HP-DDG_Buhler.

HP-DDG_Buhler contains approximately 45% crude protein and 3.7% crude fat. This report examines three aspects of feeding HP-DDG_Buhler to pigs: amino acid digestibility, energy digestibility, and growth performance.

Amino acid digestibility: supplementation required

The ileal digestibility of a diet in which crude protein and amino acids came solely from HP-DDG_Buhler was compared to one in which soybean meal was the sole source of amino acids. A nitrogen-free diet was used to estimate loss of crude protein and amino acids from the animals themselves rather than from dietary sources. All diets contained supplements of vitamins and minerals as needed to meet or exceed nutrient requirement estimates.

After feeding the diet for a five-day adaptation period, researchers collected ileal digesta samples for eight hours on days six and seven. Digesta were collected from a T-cannula fitted to the distal ileum.

The crude protein concentration of HP-DDG_Buhler was only slightly lower than that of soybean meal. Significant differences in the concentrations of a few amino acids were found, and are summarized in Table 1.

Table 1. Differences in crude protein and amino acid content of HP-DDG_Buhler and soybean meal diets

Both the apparent and standardized ileal digestibility of crude protein and most amino acids was found to be lower in HP-DDG_Buhler than in soybean meal. The lower digestibility, combined with the lower content of lysine and tryptophan in HP-DDG_Buhler, indicates that supplementation is warranted for these two amino acids.

Table 2. Standardized ileal digestibility of protein and amino acids in HP-DDG_Buhler and soybean meal diets

Energy digestibility: less energy, greater digestibility

Energy digestibility was measured by comparing pigs fed a corn-based diet to pigs fed a diet containing 50.0% corn and 48.2% HP-DDG_Buhler. Again, both the corn and HP-DDG_Buhler diets included supplemental vitamins and minerals. The feed allowance per pig per day was calculated as three times the amount needed to provide maintenance energy.

Pigs were fed the diets for a seven-day adaptation period, and then for five subsequent days while urine and fecal matter were collected. Researchers compared fecal and urinary energy excretion.

The pigs fed HP-DDG_Buhler were able to digest 89.7% of the energy in the diet, compared with 91.5% for the pigs fed corn. However, since the gross energy of HP-DDG_Buhler was much higher than that of corn, the pigs derived more energy from the HP-DDG_Buhler diet.

Table 3. Energy digestibility and retention for pigs fed corn and HP-DDG_Buhler

Growth performance and carcass traits: no difference

To measure the effect of HP-DDG_Buhleron growth performance, a total of 40 barrows with an initial body weight of 58.2 ± 2.28 kg were divided into five groups. Five diets were formulated: a control based on corn and soybean meal, and four additional diets in which HP-DDG_Buhler replaced 33%, 66%, 66%, or 100% of the soybean meal in the control diet. All diets were supplemented with crystalline lysine, and all diets containing HP-DDG_Buhler were also supplemented with crystalline threonine. Crystalline tryptophan was added to the diet in which HP-DDG_Buhler replaced 100% of soybean meal, and to one of the two diets in which it replaced 66% of soybean meal. Vitamins and minerals were added to all diets to meet or exceed current requirement estimates.

Body weight and feed disappearance for each pig were recorded on days 0, 21, 42, and 63 of the experiment. In addition, the pigs fed the control diet and the 100% HP-DDG_Buhler replacement diet were slaughtered after day 66 to determine carcass characteristics.

At no level of HP-DDG_Buhler inclusion was a significant effect on average daily gain, average daily feed intake, or gain to feed ratio observed. There was no significant difference between pigs on the 66% HP-DDG_Buhler diet with added tryptophan and the one without, showing that there is no need to supplement with tryptophan at this inclusion level.

Table 4. Growth performance of pigs fed diets with varying levels of HP-DDG_Buhler

Measurements of hot carcass weight, 10^th-rib fat, last-rib fat, 10^th-rib longissimus muscle (LM) area, and LM color did not differ between pigs fed a corn-HP-DDG_Buhler diet and pigs fed the control corn-soybean diet.

Pigs from 58kg to slaughter can be fed diets in which all SBM is replaced by HP-DDG_Buhler as long as diets are fortified with crystalline amino acids to meet requirements. This study did not address pigs less than 58kg; a previous study with HP-DDG_BFrac showed a decrease in average daily gain as the inclusion rate increased, suggesting that the same may be true of HP-DDG_Buhler as well.

Key points

• If replacing 100% of soybean meal in the diet with HP-DDG_Buhler, the diet should be fortified with crystalline lysine, threonine, and tryptophan.
• Although energy digestibility of HP-DDG_Buhler is lower than that of corn, the gross energy of HP-DDG_Buhler is so much higher that replacing corn in the diet with HP-DDG_Buhler will lead to an increase in digestible energy and metabolizable energy.
• HP-DDG_Buhler can be substituted for soybean meal in the diets of pigs from 58kg to slaughter without negatively affecting growth performance or carcass traits.

This report is based on the paper Amino acid digestibility and energy concentration in a novel source of high-protein distillers dried grains and their effects on growth performance of pigs by B. G. Kim, G. I. Petersen, R. B. Hinson, G. L. Allee, and H. H. Stein. The full paper was published in the Journal of Animal Science, volume 87, pages 4013-4021. The full text is available online.