The effects of thermal treatment of field peas (Pisum sativum L.) on nutrient and energy digestibility by growing pigs.

An experiment was conducted to measure the effect of thermal treatment on the digestibility of CP, AA, starch, NDF, ADF, and energy in field peas fed to growing pigs. Five pea-containing diets were formulated. The peas included in these diets were either not heat-treated (control) or extruded at 75, 115, or 155 degrees C or pelleted at 75 degrees C. A N-free diet was also included in the experiment to measure basal endogenous losses of CP and AA. The 6 diets were fed to 6 growing pigs (initial BW: 69.3 +/- 2.9 kg) that were allotted to dietary treatments in a 6 x 6 Latin square design. A T-cannula was installed in the distal ileum of each pig, allowing for the collection of ileal digesta. Each experimental period lasted 9 d; fecal samples were collected on d 6 and 7, and ileal samples were collected on d 8 and 9 of each period. Apparent ileal digestibilities (AID) for CP, AA, starch, and energy and standardized ileal digestibility values (SID) for CP and AA were calculated. Apparent total tract digestibilities (ATTD) for NDF, ADF, starch, and energy were also calculated. As the extrusion temperature increased, the AID and SID for CP and all AA, except Pro, increased (quadratic, P < 0.05). In contrast, except for Arg and Pro, the peas that were pelleted at 75 degrees C had AID and SID for CP and AA that were similar to those obtained for the control peas but less (P < 0.05) than the AID for the peas that were extruded at 75 degrees C. The AID for starch and energy increased (linear, P < 0.001) as the extrusion temperature increased to 155 degrees C (from 89.8 to 95.9% and from 71.5 to 79.0%, respectively), but the AID for starch and energy in the pelleted diet was not different from the AID in the control diet (90.1 vs. 89.8% and 69.1 vs. 71.5%, respectively). The ATTD for starch varied from 98.6 to 99.7% and did not differ among treatments. Likewise, no differences were observed for the ATTD of NDF and ADF. However, the ATTD for energy in the diets increased from 89.0 to 93.3% (linear and quadratic, P < 0.05) as field peas were extruded, and the ATTD for energy in the pelleted diet was also greater (P < 0.05) than that of the control diet (91.6 vs. 89.0%). In conclusion, extrusion of field peas increases the AID of CP, AA, starch, and energy and the ATTD of energy. Pelleting field peas at 75 degrees C does not influence the AID of nutrients or energy but improves the ATTD of energy.

Additivity of values for apparent and standardized ileal digestibility of amino acids in mixed diets fed to growing pigs.

The objective of this experiment was to determine whether the digestibility of CP and AA in a mixed diet fed to growing pigs is better predicted when based on standardized ileal digestibility coefficients (SID) or apparent ileal digestibility coefficients (AID). Eight growing pigs (initial BW = 92.1 +/- 3.19 kg) were surgically equipped with a T-cannula in the distal ileum and arranged in an 8 x 8 Latin square design with eight diets and eight periods. Three of the diets contained corn, soybean meal (SBM), or canola meal (CM) as the sole source of CP and AA. Four mixed diets also were formulated using corn and soybean meal (CS); corn and canola meal (CCM); soybean meal and canola meal (SCM); or corn, soybean meal, and canola meal (CSCM). A N-free diet was used to measure the basal ileal endogenous losses (IAAend) of CP and AA. Pigs were fed each of the eight diets during one 7-d period, and ileal digesta were collected during two 10-h periods on d 6 and 7. The AID values were calculated for CP and AA in all diets, except the N-free diet. By correcting the AID for IAAend, the SID for CP and AA in each of the seven protein-containing diets were calculated. As expected, the AID for CP and the majority of AA were greater in SBM than in corn and CM (P < 0.05); however, the SID for CP and most AA did not differ between corn and SBM. For the majority of the AA, SID were less (P < 0.05) in CM than in the other two ingredients. Using the AID and the SID that were measured for CP and AA in corn, SBM, and CM, the AID and the SID in the four mixed diets were predicted and compared with the measured values for these diets. For the three mixed diets containing corn, the measured AID for CP and most AA were greater (P < 0.05) than the predicted AID, but with a few exceptions, no differences between predicted and measured values for SID were observed. For the diet based on SCM, there were no differences between predicted and measured values regardless of the procedure used, except for the AID of Ser. The results of this experiment demonstrate that the digestibility coefficients for a mixed diet containing low-protein feed ingredients, such as corn, are more accurately predicted using SID than AID.

Calcium, phosphorus, and amino acid digestibility in low-phytate corn, normal corn, and soybean meal by growing pigs.

Nine growing barrows were equipped with a T-cannula in the distal ileum and used to determine apparent ileal (AID) and apparent total-tract digestibility (ATTD) coefficients of Ca and P in low-phytate corn, normal corn, soybean meal, and in diets where soybean meal was mixed with low-phytate corn or normal corn. The AID and the standardized ileal digestibility coefficients (SID) of CP and AA also were determined. The animals (initial BW = 29.3 +/- 1 kg) were allotted to a 9 x 9 Latin square with nine diets and nine periods. Three diets contained low-phytate corn, normal corn, and soybean meal as their sole source of CP, AA, Ca, and P, respectively. Three additional diets were identical to these diets except that limestone and monosodium phosphate were added. Two diets contained low-phytate corn or normal corn and soybean meal, limestone, and monosodium phosphate, and the final diet was a N-free diet. The AID and ATTD of Ca were higher (P < 0.05) for low-phytate corn than for normal corn (70.0 and 69.1% vs. 47.4 and 49.6%, respectively). The AID and ATTD for Ca in soybean meal (50.9 and 46.7%, respectively) did not differ from values for normal corn but were lower (P < 0.05) than for low-phytate corn. The AID and ATTD for P from low-phytate corn (56.5 and 54.5%, respectively) were greater (P < 0.05) than from normal corn (28.3 and 28.8%, respectively), whereas soybean meal had intermediate AID and ATTD for P (37.2 and 38.0%, respectively). The AID and ATTD of P increased (P < 0.05) when monosodium phosphate was added to normal corn (44.9 and 49.8%, respectively) and soybean meal (49.6 and 46.2%, respectively), but adding monosodium phosphate to low-phytate corn, did not alter either AID (49.7%) or ATTD (50.7%) of P. No differences between AID and ATTD for Ca or P within the same diet were observed. The AID of Arg, Asp, Gly, Ile, Lys, Phe, Thr, and Val were greater (P < 0.05) in low-phytate corn than in normal corn. The AID of all AA in soybean meal were greater (P < 0.05) than in both types of corn, with the exception of Ala, Cys, Leu, and Met. The SID of Lys, Phe, and Thr were higher (P < 0.05) in low-phytate corn than in normal corn. Because low-phytate corn has a higher digestibility of Ca and P, less inorganic Ca and P need to be supplemented to diets containing low-phytate corn than to those containing normal corn, and P excretion may be decreased when low-phytate corn is used in the diet.

Assessment of the feeding value of South Dakota-grown field peas (Pisum sativum l.) for growing pigs.

Four experiments were conducted to investigate the feeding value of South Dakota-grown field peas (Pisum sativum L.) for growing pigs. In Exp. 1, 96 pigs (initial BW = 22 +/- 3.35 kg) were allotted to four treatment groups (four pigs per pen, six replicate pens per treatment) and fed growing (0.95% Lys) and finishing (0.68% Lys) diets containing 0, 12, 24, or 36% field peas (as-fed basis). There were no differences among the treatment groups in ADG, ADFI, or G:F. Likewise, there were no differences in backfat thickness or lean meat percent among treatment groups, but pigs fed diets containing 12, 24, or 36% field peas had greater (P < 0.05) loin depths than pigs fed the control diet. In Exp. 2, 120 pigs (initial BW = 7.8 +/- 1.04 kg) were allotted to four treatment groups 2 wk after weaning. Pigs were then fed diets containing 0, 6, 12, or 18% field peas (as-fed basis) during the following 4 wk. There were five pigs per pen and six replicate pens per treatment. Results of the experiment showed no differences in ADG, ADFI, or G:F among treatment groups. In Exp. 3, apparent (AID) and standardized (SID) ileal digestibility coefficients of CP and AA in field peas and soybean meal were measured using six individually penned growing pigs (initial BW = 36.5 +/- 2.1 kg) arranged in a repeated 3 x 3 Latin square design. The AID for Met, Trp, Cys, and Ser, and the SID for Met, Trp, and Cys were lower (P < 0.05) in field peas than in soybean meal; but for CP and all other AA, no differences in AID or SID were observed between the two feed ingredients. Experiment 4 was an energy balance experiment conducted to measure the DE and ME concentrations in field peas and corn. Six growing pigs (initial BW = 85.5 +/- 6.5 kg) were placed in metabolism cages and fed diets based on field peas or corn and arranged in a two-period switch-back design. The DE values for field peas and corn (3,864 and 3,879 kcal/kg DM, respectively) were similar, but the ME of corn was higher (P < 0.05) than the ME of field peas (3,825 vs. 3,741 kcal ME/kg DM). The results from the current experiments demonstrate that the nutrients in South Dakota-grown field peas are highly digestible by growing pigs. Therefore, such field peas may be included in diets for nursery pigs and growing-finishing pigs in amounts of at least 18 and 36%, respectively, without negatively affecting pig performance.