Digestibility of energy and phosphorus and concentration of metabolizable energy in a new source of high-protein distillers dried grains fed to growing pigs

Recently a high-protein distillers dried grains (HP-DDGS; ProCap DDGS, Marquis Energy, Hennepin, IL) was developed and the HP-DDGS has greater concentrations of CP and fat, but contains less fiber compared with conventional DDGS, which may affect the digestibility of energy and P and concentrations of DE and ME. There are, however, no data for the nutritional value of this new source of DDGS. Therefore, 2 experiments were conducted to test the hypothesis that concentrations of DE and ME, and standardized total tract digestibility (STTD) of P in HP-DDGS are greater than in conventional DDGS.

Experimental design

Exp. 1. Concentrations of DE and ME

Twenty-four barrows (initial BW: 32.7 ± 3.1 kg) were allotted to a randomized complete block design with 3 diets and 8 replicate pigs per diet. Pigs were housed individually in metabolism crates that were equipped with a self-feeder, a nipple waterer, and a slatted floor. A screen and a urine pan were placed under the slatted floor for the total, but separate, collection of urine and fecal samples.

A basal diet containing corn as the sole source of energy and 2 diets containing corn and each source of DDGS were formulated – thus, a total of 3 diets were used.

Feed consumption was recorded daily and pigs were fed experimental diets for 13 d. The initial 7 d were considered the adaptation period to the diet, whereas urine and fecal samples were collected for 4 d according to standard procedures using the marker to marker approach.

Exp. 2. Digestibility of P

Thirty-two barrows (initial BW: 20.2 ± 0.9 kg) were allotted to a randomized complete block design with 4 diets and 8 replicate pigs per diet. Two diets were formulated by mixing each source of DDGS with sucrose and cornstarch and DDGS was the only source of P in these 2 diets. Two additional diets that were similar to the previous 2 diets with the exception that 500 units of microbial phytase (Quantum Blue®, AB Vista, Marlborough, UK) were added to these diets were also formulated. Housing, feeding, and sample collection were as for Exp. 2 with the exception that only fecal samples were collected in Exp. 2, and that the adaptation period was 5 d rather than 7 d. Values for the STTD of P were calculated by correcting apparent total tract digestibility of P for the basal endogenous loss of P (NRC, 2012; 190 mg/kg DMI).

Results

On an 88% DM basis, HP-DDGS contained more GE, CP, and acid-hydrolyzed ether extract and less P compared with conventional DDGS (Table 1).

Concentrations of DE and ME of the HP-DDGS were greater (P < 0.05) compared with conventional DDGS (Table 2). It is likely that the reason for the greater DE and ME in HP-DDGS compared with conventional DDGS is the greater concentrations of protein and fat in the ingredient. Thus, diets formulated with the HP-DDGS will contain more energy than diets formulated with conventional DDGS.

Inclusion of phytase in the diet containing HP-DDGS increased (P < 0.05) the STTD of P, but addition of phytase to the conventional DDGS did not increase STTD of P (interaction, P < 0.001; Table 3). Regardless of phytase, STTD of P was greater (P < 0.001) in conventional DDGS than in HP-DDGS. It is likely that the reason for the greater P digestibility in conventional DDGS compared with HP-DDGS is the fermentation during the DDGS production that may release P from phytate.

Key points

• A new source of high protein DDGS (i.e., HP-DDGS) contains more GE, CP, and fat and less P compared with conventional DDGS.
• HP-DDGS has greater concentrations of DE and ME compared with conventional DDGS.
• HP-DDGS has less STTD of P compared with conventional DDGS but the use of microbial phytase increases the STTD of P in HP-DDGS.
• Effects of microbial phytase on the STTD of P in conventional DDGS is less than in HP-DDGS.

Table 1. Nutrient composition of HP-DDGS and conventional DDGS¹

¹All values except DM were adjusted to 88% DM.

Table 2. DE and ME in HP-DDGS and conventional DDGS (Exp. 1; as-fed basis)

Table 3. STTD of P in 2 sources of DDGS fed to growing pigs (Exp. 2)

^a-bWithin a row, means without a common superscript differ (P < 0.05).