The primary objective of this experiment was to determine the effects of heat treatment on the standardized ileal digestibility (SID) of amino acids (AA) in corn distillers dried grains with solubles (DDGS) fed to growing pigs. The second objective was to develop regression equations that may be used to predict the concentration of SID AA in corn DDGS. A source of corn DDGS was divided into 4 batches that were either not autoclaved or autoclaved at 130°C for 10, 20, or 30 min. Four diets containing DDGS from each of the 4 batches were formulated with DDGS being the only source of AA and CP in the diets. A N-free diet also was formulated and used to determine the basal endogenous losses of CP and AA. Ten growing pigs (initial BW: 53.5 ± 3.9 kg) were surgically equipped with a T-cannula in the distal ileum and allotted to a replicated 5 × 4 Youden square design with 5 diets and 4 periods in each square. The SID of CP decreased linearly (P < 0.05) from 77.9% in non-autoclaved DDGS to 72.1, 66.1, and 68.5% in the DDGS samples that were autoclaved for 10, 20, or 30 min, respectively. The SID of lysine was quadratically reduced (P < 0.05) from 66.8% in the non-autoclaved DDGS to 54.9, 55.3, and 51.9% in the DDGS autoclaved for 10, 20, or 30 min, respectively. The concentrations of SID Arginine, Histidine, Leucine, Lysine, Methionine, Phenylalanine, or Threonine may be best predicted by equations that include the concentration of acid detergent insoluble N in the model (r² = 0.76, 0.68, 0.67, 0.84, 0.76, 0.73, or 0.54, respectively). The concentrations of SID Isoleucine and Valine were predicted (r² = 0.58 and 0.54, respectively) by the Lysine:CP ratio, whereas the concentration of SID Tryptophan was predicted (r² = 0.70) by the analyzed concentration of Tryptophan in DDGS. In conclusion, the SID of AA is decreased as a result of heat damage and the concentration of SID AA in heat-damaged DDGS may be predicted by regression equations developed in this experiment.

Dietary inclusion of salts of organic acids may modulate intestinal microbiota and enhance performance of pigs. Published data on the effects of potassium formate (KF; pH 6.0–8.5) on pig performance are scarce compared with that of potassium diformate (KDF; pH 4.1–4.5). Therefore, the objective was to evaluate the effects of KDF or KF supplementation on performance of 8- to 22-kg pigs. A 35-d growth trial was conducted with 144 PIC pigs (initial BW of 7.9 ± 0.69 kg) with 6 pigs (3 gilts and 3 barrows) per pen and 8 pens per treatment. Pigs were assigned to 3 diets based on corn (Zea mays), wheat (Triticum aestivum), and soybean (Glycine max) meal for each of the prestarter (days 1–14) and starter phases (days 15–35). The basal diet was supplemented with KDF at 1.20% or KF at 1.56% replacing corn starch to create diets 2 and 3, respectively, to provide a constant formate content. The ADG and feed conversion ratio (FCR) were not affected by the addition of KDF or KF during the prestarter phase. Addition of KDF or KF to the basal diet increased (P < 0.01) ADG and final BW and improved FCR (P < 0.05) during the starter and the overall 35-d period. The ADFI was not affected by the treatments. Performance of pigs fed diets supplemented with KF and KDF were similar. Diarrhea incidences were observed during week 1 but no differences were observed (P > 0.05) among treatments in term of the number of antibiotic treatments or fecal consistency scores. Overall, the supplementation of 1.56% KF or 1.20% KF improved performance of weaned pigs. Copyright © 2013. American Society of Animal Science .

Over the last decade, the nutritional requirements of lactating modern genotype sows have increased. The current nutritional recommendations might be unable to meet the needs of increased litter size and milk production, and thus the nutritional requirements need to be re-evaluated. The current study was conducted to investigate the effects of dietary methionine to lysine (Met:Lys) ratios on the performance of and methionine metabolism in lactating sows. During the 1st week of lactation, piglets reared on sows in the 0.37 to 0.57 Met:Lys ratio groups grew faster than those reared on sows in the control group (0.27) (P < 0.01). The 0.37-ratio group showed increased levels of GSH-Px in plasma during lactation (P < 0.01) and decreased concentrations of urea nitrogen in the plasma of sows (P < 0.05). Compared with the 0.27-ratio group, the levels of T-AOC and GSH-Px in the plasma and homocysteine in the milk of lactating sows were significantly increased in sows in the 0.47-ratio group (P < 0.01). In sows fed a 0.57-ratio diet, the levels of glutathione and taurine in the plasma and milk were improved significantly during lactation. However, the content of TBARS in the blood (P < 0.05 at day 7 and P = 0.06 at weaning day) was increased (P < 0.01). Moreover, there were linear increases in the levels of homocysteine in the blood and milk of sows during the lactation period (P < 0.01) with increased dietary Met:Lys ratios in the lactation diet. The current study indicated that increasing the dietary Met:Lys ratio (0.37~0.57) in the lactation diet had no significant effect on the overall performance of sows or the colostrum and milk composition, but it increased piglet mean BW and piglet ADG during the first week of lactation. Increasing dietary methionine levels had no significant effect on antioxidant function in lactation sows, even though it increased levels of GSH and GSH-Px in the plasma of sows during lactation. However, the content of homocysteine in the plasma and milk increased during lactation due to a high level of dietary methionine.

Three 21-d experiments were conducted to determine the optimum standardized ileal digestible (SID) Ile:Lys ratio in 10- to 22-kg and 24- to 39-kg pigs. In Exp. 1, 144 Yorkshire pigs (initial BW = 10.2 kg) were assigned to 6 diets with 6 pens per treatment. Diets 1 to 5 were formulated to contain 5 graded SID Ile:Lys (44, 51, 57, 63, and 70%), 1.18% SID Leu, and 0.90% SID Lys (second limiting). Diet 6 (diet 5 with added Lys) was formulated (1.06% SID Lys) as a positive control. Pigs fed diet 6 had higher (P < 0.05) ADG and G:F and lower (P < 0.05) plasma urea N (PUN) than pigs fed diet 5 (P < 0.02), indicating that Lys was limiting in diets 1 to 5. Final BW, ADG, and ADFI increased (linear and quadratic, P < 0.05) while G:F and PUN at d 21 were not affected (P > 0.10) by dietary Ile:Lys. Overall, ADG and ADFI were highest for pigs fed diet 2 (51% SID Ile:Lys). In Exp. 2, 216 Yorkshire pigs (initial BW = 9.6 kg) were assigned to 9 diets with 6 pens per treatment. Diets 1 to 4 contained 0.40, 0.47, 0.54, and 0.61% SID Ile, respectively, and 1.21% SID Lys; diets 5 to 8 contained 0.72, 0.84, 0.96, and 1.08% SID Lys, respectively, and 0.68% SID Ile. Diet 9 was high in both Ile and Lys (0.68% SID Ile and 1.21% SID Lys). All diets contained 1.21% SID Leu. The ADG and G:F increased (linear and quadratic, P < 0.05) as SID Ile:Lys increased (diets 1 to 4 and 9). The ADG and G:F increased (linear, P < 0.05) as SID Lys increased (diets 5 to 9). The PUN at d 21 decreased (linear, P < 0.05) by increasing dietary Ile:Lys. The SID Ile:Lys to optimize ADG was 46% by curvilinear plateau or exponential regression. For G:F, the optimal SID Ile:Lys was 47 and 51% by curvilinear plateau and exponential regressions, respectively. In Exp. 3, 80 pigs (PIC 327 × C23; initial BW = 24.0 kg) were allotted to 5 treatments with 4 pigs per pen. Diets 1 to 5 were formulated to contain 5 graded SID Ile:Lys (39, 46, 53, 61, and 68%), 1.17% SID Leu, and 0.91% SID Lys (second limiting). Final BW and ADG increased (linear and quadratic, P < 0.05) and ADFI increased (linear, P = 0.047) as SID Ile:Lys increased. Using ADG and G:F, the optimum SID Ile:Lys was 54 and 53%, respectively, by curvilinear plateau and exponential regression. The PUN was minimized at 53 and 59% SID Ile:Lys by curvilinear plateau and broken line regression. Overall, the average optimum SID Ile:Lys was approximately 51% for 10- to 22-kg pigs and 54% for 24- to 39-kg pigs fed diets containing nonexcess levels of Leu. Copyright © 2014. American Society of Animal Science .

Information about the relative bioavailability (RBV) of L-Methionine (L-Met) compared with DL-Methionine (DL-Met) for pigs is limited. Therefore, 2 experiments were conducted to compare the RBV of L-Met and DL-Met for weaned pigs. In Exp. 1, 252 PIC pigs (initial BW of 7.9 kg) were assigned to 7 treatments with 6 pen replicates for 21 d. Diets included a basal diet (BD; 72% of the NRC recommendation for Met), the BD + 0.05% DL-Met or L-Met (84% of the NRC recommendation), the BD + 0.10% DL-Met or L-Met (97% of the NRC recommendation), and the BD + 0.15% DL-Met or L-Met (110% of the NRC recommendation). In Exp. 2, 3 diets (the BD, and the BD + 0.15% DL-Met or L-Met), which were used in Exp. 1, were fed to 144 PIC pigs (initial BW of 7.8 kg) for 21 d to confirm the effects of the same quantities of DL-Met or L-Met to a Met-deficient diet on performance of 8 to 15 kg pigs. In Exp. 1, the overall ADG and G:F increased linearly (P < 0.01) by adding DL-Met or L-Met. Performance of pigs fed diets supplemented with the same inclusion levels of DL-Met and L-Met were not different (P > 0.60). Using a slope-ratio regression, the RBV of L-Met relative to DL-Met was 99.6% (95% confidence intervals: 65–134%) based on ADG as a response of supplemented Met intake. In Exp. 2, 0.15% supplementation with DL-Met or L-Met increased ADG (P < 0.05) and tended to improve G:F (P = 0.065), but there was no effect on Met source (P > 0.05). Overall, these data indicated that L-Met and DL-Met are equally bioavailable as Met sources for weaned pigs. Copyright © 2016. American Society of Animal Science .