Changes in food intake, metabolic parameters and insulin resistance are induced by an isoenergetic, medium-chain fatty acid diet and are associated with modifications in insulin signalling in isolated rat pancreatic islets.

Long-chain fatty acids are capable of inducing alterations in the homoeostasis of glucose-stimulated insulin secretion (GSIS), but the effect of medium-chain fatty acids (MCFA) is poorly elucidated. In the present study, we fed a normoenergetic MCFA diet to male rats from the age of 1 month to the age of 4 months in order to analyse the effect of MCFA on body growth, insulin sensitivity and GSIS. The 45% MCFA substitution of whole fatty acids in the normoenergetic diet impaired whole body growth and resulted in increased body adiposity and hyperinsulinaemia, and reduced insulin-mediated glucose uptake in skeletal muscle. In addition, the isolated pancreatic islets from the MCFA-fed rats showed impaired GSIS and reduced protein kinase Ba (AKT1) protein expression and extracellular signal-related kinase isoforms 1 and 2 (ERK(1/2)) phosphorylation, which were accompanied by increased cellular death. Furthermore, there was a mildly increased cholinergic sensitivity to GSIS. We discuss these findings in further detail, and advocate that they might have a role in the mechanistic pathway leading to the compensatory hyperinsulinaemic status found in this animal model.

Plasma metabolomics indicates metabolic perturbations in low birth weight piglets supplemented with arginine.

Large profit losses in the swine industry can be attributed to morbidity and mortality of piglets before weaning, especially in the low birth weight (LBW) piglet. Recent evidence suggests sow's milk contains insufficient concentrations of Arg to support optimal growth and health of piglets. Therefore, our objective was to assess global metabolomic profiles and the potential for Arg supplementation to promote growth of LBW (≤0.9 kg BW) and average birth weight (ABW; 1.3 to 1.5 kg BW) piglets. Piglets were selected in littermate pairs at processing to receive either Arg or an isonitrogenous control (Ala) and weighed daily to assess growth rate, and blood was collected at approximately 16 d of age for metabolomics analysis. In terms of growth, LBW and ABW piglets supplemented with Arg weighed 22.3 and 12.7% less, respectively, at d 16 compared with Ala-supplemented piglets of the same birth weight group. Overall, differences ( < 0.05) were observed among treatments for metabolic pathways involving energy (i.e., tricarboxylic acid cycle intermediates), AA, nucleotides, and fatty acids. Increased nucleotide turnover, indicative of an increase in DNA damage and cell death, was particularly noted in the LBW piglet. However, Arg supplementation reduced these effects to levels comparable to those observed in ABW piglets. Moreover, changes in glucose metabolism suggested a compromised ability to extract energy from dietary sources may have occurred in the LBW piglet, but these effects were partially recovered by Arg supplementation. We conclude that a reduction in the growth potential of LBW piglets may be associated with alterations in multiple metabolic pathways, and further reduction due to Arg supplementation may have resulted from perturbations in multiple metabolic pathways.

Amino acid digestibility and concentration of digestible and metabolizable energy in a threonine biomass product fed to weanling pigs.

Production of crystalline l-Thr results in the generation of a Thr biomass that contains more than 80% CP, 5.20% Lys, 5.10% Val, 4.52% Thr, 4.15% Ile, and 1.06% Trp. This Thr biomass product can possibly be used as a feed ingredient in diets fed to weanling pigs, but there is little information about the nutritional value of this product. The objective of this work was to determine the AA digestibility and energy concentration in Thr biomass and to compare these values to values obtained for fish meal in diets fed to pigs. The apparent ileal digestibility (AID) and the standardized ileal digestibility (SID) of CP and AA were determined in Exp. 1. Nine pigs (initial BW: 13.4 ± 2.5 kg) were equipped with a T-cannula in the distal ileum and allotted to a triplicated 3 × 3 Latin square design with 3 diets and 3 periods in each square. One diet contained 20.0% Thr biomass as the sole source of AA, and a second diet contained 25.0% fish meal as the sole source of AA. The last diet was a N-free diet that was used to measure basal endogenous losses of AA and CP. Results indicated that the AID and SID of all AA except Trp, Gly, and Pro were greater (P < 0.05) in Thr biomass than in fish meal. In Exp. 2, 24 pigs (initial BW: 18.1 ± 3.5 kg) were placed in metabolism cages and randomly allotted to 3 diets. The first diet contained 96.4% corn, the second diet contained 79.3% corn and 17.0% Thr biomass, and the third diet contained 75.3% corn and 24.0% fish meal. Total collection of feces and urine was performed for 5 d after a 5-d adaptation period, and all samples of ingredients, diets, feces, and urine were analyzed for GE. Digestible energy and ME were then calculated. The DE in the Thr biomass was greater (P < 0.05) than in fish meal and corn (4,935 vs. 3,938 and 3,939 kcal DE/kg DM, respectively), and the ME in the Thr biomass was also greater (P < 0.05) than in fish meal and corn (4,335 vs. 3,508 and 3,839 kcal ME/kg DM, respectively). Results from these experiments indicate that Thr biomass is an excellent source of AA and ME. Therefore, the Thr biomass is a viable ingredient that can be used as an alternative to fish meal and possibly other animal proteins in diets for pigs.

Effects of balancing crystalline amino acids in diets containing heat-damaged soybean meal or distillers dried grains with solubles fed to weanling pigs.

Two experiments were conducted to investigate if adjustments in diet formulations either based on total analysed amino acids or standardized ileal digestible (SID) amino acids may be used to eliminate negative effects of including heat-damaged soybean meal (SBM) or heat-damaged corn distillers dried grains with solubles (DDGS) in diets fed to weanling pigs. In Experiment 1, four corn-SBM diets were formulated. Diet 1 contained non-autoclaved SBM (315 g/kg), and this diet was formulated on the basis of analysed amino acid concentrations and using SID values from the AminoDat® 4.0 database. Diet 2 was similar to Diet 1 in terms of ingredient composition, except that the non-autoclaved SBM was replaced by autoclaved SBM at 1 : 1 (weight basis). Diet 3 was formulated using autoclaved SBM and amino acid inclusions in the diet were adjusted on the basis of analysed total amino acid concentrations in the autoclaved SBM and published SID values for non-autoclaved SBM (AminoDat® 4.0). Diet 4 also contained autoclaved SBM, but the formulation of this diet was adjusted on the basis of analysed amino acids in the autoclaved SBM and SID values that were adjusted according to the degree of heat damage in this source of SBM. Pigs (160; initial BW: 10.4 kg) were allotted to the four treatments with eight replicate pens per treatment in a randomized complete block design. Diets were fed to pigs for 21 days. The gain to feed ratio (G : F) was greater (P<0.05) for pigs fed Diet 1 compared with pigs fed the other diets and pigs fed Diet 4 had greater (P<0.05) G : F than pigs fed Diet 2. In Experiment 2, 144 pigs (initial BW: 9.9 kg) were allotted to four diets with eight replicate pens per diet. The four diets contained corn, SBM (85 g/kg) and DDGS (220 g/kg), and were formulated using the concepts described for Experiment 1, except that heat-damaged DDGS, but not heat-damaged SBM, was used in the diets. Pigs fed Diet 1 had greater (P<0.05) G : F than pigs fed Diet 2, but no differences were observed for G : F among pigs fed diets containing autoclaved DDGS. Results demonstrate that the negative effects of heat damage of SBM or DDGS may be ameliorated if the reduced concentration and digestibility of amino acids in heat-damaged SBM or DDGS is taken into account in diet formulation. Further research is needed to improve the prediction of the ileal digestibility of amino acids in heat-processed ingredients used in practical diet formulations.

Digestibility by growing pigs of amino acids in heat-damaged sunflower meal and cottonseed meal.

Two experiments were conducted to determine the effects of heat damage, achieved by autoclaving, on the nutritional composition and on the standardized ileal digestibility (SID) of AA in sunflower meal (SFM) and cottonseed meal (CSM) fed to growing pigs. The second objective was to establish a relationship between the concentration of SID AA in SFM and CSM and the concentration of fiber components, reducing sugars, and AA. In Exp. 1, 10 growing pigs (initial BW: 23.1 ± 1.3 kg) were surgically equipped with a T-cannula in the distal ileum and allotted to a replicated 5 × 5 Latin square design with 5 diets and 5 periods in each square. A common source of SFM was separated into 4 batches that were either not autoclaved or autoclaved at 130°C for 20, 40, or 60 min. Four diets (approximately 14.5% CP) that contained each of the 4 batches of SFM were formulated, and SFM was the only source of CP and AA in the diets. A N-free diet that was used to determine the basal endogenous losses of CP and AA from pigs was also formulated. Each period consisted of 5 d of adaptation to the diets followed by 2 d of ileal digesta collection. The SID of Lys in SFM was reduced (linear, P < 0.05) from 83.2% in nonautoclaved SFM to 63.5% in SFM autoclaved for 60 min at 130°C. The concentrations of total Lys and reducing sugars in SFM may be used as predictors (R(2) = 0.85) of the concentration of SID Lys in SFM. In Exp. 2, 10 growing pigs (initial BW: 35.0 ± 1.5 kg) were surgically equipped with a T-cannula in the distal ileum and allotted to a replicated 5 × 5 Latin square design with 5 diets and 5 periods in each square. A source of CSM was separated into 4 batches that were either not autoclaved or autoclaved at 130°C for 15, 35, or 60 min. Four diets (approximately 13.4% CP) containing CSM as the only source of CP and AA were formulated. A N-free diet was also formulated and used as described for Exp. 1. The SID of Lys in nonautoclaved CSM (66.2%) was greater (P < 0.05) than in autoclaved (60 min at 130°C) CSM (54.1%). The equation (R(2) = 0.68) that best predicted the concentration of SID Lys in CSM included the concentration of ADIN. In conclusion, heat damage reduces the SID of AA in SFM and CSM. For SFM, the concentration of SID Lys may be predicted from the concentrations of total Lys and reducing sugars. The concentration of ADIN may be used to predict the concentration of SID Lys in CSM.

Energy concentration and amino acid digestibility in corn and corn coproducts from the wet-milling industry fed to growing pigs.

Two experiments were conducted to determine DE and ME and the apparent ileal digestibility (AID) and the standardized ileal digestibility (SID) of CP and AA in corn and corn coproducts (high-fat corn germ [HFCG], corn bran, liquid corn extractives [LCE], and a mixture of corn germ meal and LCE [CGM-LCE]) fed to growing pigs. In Exp. 1, 40 growing barrows (initial BW: 33.4 ± 5.77 kg) were housed individually in metabolism cages and randomly allotted to 1 of 5 diets. A corn-based diet (97.4% corn) and 4 diets that contained both corn and each of the corn coproducts were formulated. Each diet was fed to 8 pigs. Feces and urine samples were collected using the marker to marker method with 5-d adaptation and 5-d collection periods. The DE and ME were calculated using the difference procedure. The concentrations of DE and ME in HFCG, corn bran, LCE, and CGM-LCE were less (P < 0.05) than in corn. Among corn coproducts, the concentration of DE in HFCG was greater (P < 0.05) than in corn bran, but the DE in corn bran was not different from DE values in LCE and CGM-LCE. No differences were observed in the ME concentrations among corn coproducts. In Exp. 2, 6 growing barrows (initial BW: 96.6 ± 1.16 kg) with a T-cannula in the distal ileum were randomly allotted to a 6 × 6 Latin square design with 6 diets and 6 periods. A N-free diet and 5 diets that contained corn, HFCG, corn bran, LCE, or CGM-LCE as the sole source of CP and AA were formulated. Each period lasted 7 d and ileal digesta were collected on d 6 and 7 of each period. The SID of CP and all indispensable AA was greater (P < 0.05) in corn than in all corn coproducts with the exception that the SID of Lys in corn was not different from the SID of Lys in HFCG, and the SID of Trp in corn was also not different from the SID of Trp in CGM-LCE. Among corn coproducts, the SID of CP, Arg, and Lys were greater (P < 0.05) in HFCG and CGM-LCE than in corn bran, the SID of Lys and Val was greater (P < 0.05) in LCE than in corn bran, and the SID of Arg was greater (P < 0.05) in HFCG and CGM-LCE than in LCE, but for the remaining indispensable AA, no differences among corn coproducts were observed. In conclusion, the corn coproducts used in these experiments contain less ME and have reduced SID of most AA compared with corn, but there are no differences in ME among corn coproducts and only few differences in the SID of indispensable AA among HFCG, corn bran, LCE, and CGM-LCE.

Amino acid and phosphorus digestibility and concentration of digestible and metabolizable energy in hydrolyzed feather meal fed to growing pigs.

Two experiments were conducted to determine the standardized ileal digestibility (SID) of AA (Exp. 1), the standardized total tract digestibility (STTD) of P, and the concentration of DE and ME (Exp. 2) in hydrolyzed feather meal (FM) fed to growing pigs. Eight samples of FM were obtained from 4 different processing plants (FM1, FM2, FM3, and FM4). Each plant provided samples of FM without and with added blood. In Exp. 1, 10 barrows (initial BW: 24.0 ± 0.8 kg) were prepared with a T-cannula in the distal ileum and allotted to a 10 × 10 Latin square design with 10 diets and ten 7-d periods. A N-free diet, a diet based on soybean meal (SBM), and 8 diets based on a combination of SBM and each of the 8 sources of FM were formulated. Values for the SID of CP and AA in each source of FM were calculated using the difference procedure. The SID of CP and all AA was different (P < 0.001) among sources of FM. Among the indispensable AA, the overall effect of addition of blood was statistically significant (P < 0.05) for the SID of Ile, Leu, Lys, Phe, and Val, but for some sources, the SID of these AA was increased by addition of blood, whereas for other sources, the SID was reduced or not changed (interaction, P < 0.05). As an example, the SID of Lys in FM3 and FM4 with added blood were greater (P < 0.05) than in FM3 and FM4 without blood, but no difference in the SID of Lys was observed for FM1 and FM2 without and with blood (interaction, P < 0.01). In Exp. 2, 72 growing barrows (initial BW: 13.3 ± 1.5 kg) were used with 9 diets and 8 replicate pigs per diet. A corn-diet consisting of 98.4% corn was formulated and 8 additional diets were formulated by mixing corn with 25% FM. The STTD of P and the DE and ME of each source of FM were calculated using the difference procedure. The STTD of P tended (P = 0.09) to be different among FM sources and the STTD of P in FM with added blood was less than in FM without blood. On a DM basis, DE and ME values were affected (P < 0.05) by both source of FM and addition of blood. However, an interaction (P < 0.05) between source of FM and addition of blood for ME was observed because addition of blood to FM3 and FM4 reduced (P < 0.05) the ME, whereas addition of blood to FM1 and FM2 had no impact on ME. In summary, the SID of AA, STTD of P, and the energy concentration vary among sources of FM and the effects of adding blood to FM is not consistent among sources.

Effects of graded levels of microbial phytase on the standardized total tract digestibility of phosphorus in corn and corn coproducts fed to pigs.

An experiment was conducted to determine the influence of adding graded levels of microbial phytase to corn, distillers dried grains with solubles (DDGS), high-protein distillers dried grains (HP-DDG), and corn germ on the standardized total tract digestibility (STTD) of P. A second objective was to develop regression equations to predict the response of adding phytase to each of these ingredients. Four corn-based diets, 4 DDGS-based diets, 4 HP-DDG-based diets, and 4 corn germ-based diets were formulated. The 4 diets with each ingredient were formulated to contain 0, 500, 1,000, or 1,500 phytase units (FTU)/kg. A P-free diet was also formulated to determine basal endogenous losses of P. A total of 102 pigs (initial BW: 18.2 ± 2.1 kg) were individually housed in metabolism cages equipped with a feeder, a nipple drinker, and a screen floor that allowed for total collection of feces. Pigs were allotted to the 17 diets in a randomized complete block design with 6 replicate pigs per diet. Pigs were fed their respective diets for 12 d, and feces were collected quantitatively from d 6 to 11. Supplementation with 500, 1,000, or 1,500 FTU of microbial phytase/kg increased (linear, P < 0.01; quadratic, P < 0.05) the STTD of P in corn from 40.9 to 67.5, 64.5, and 74.9%, respectively, tended to increase (linear, P = 0.07) the STTD of P in DDGS from 76.9 to 82.9, 82.5, and 83.0%, respectively, increased (linear, P < 0.01; quadratic, P < 0.05) the STTD of P in HP-DDG from 77.1 to 88.0, 84.1, and 86.9%, respectively, and increased (linear and quadratic, P < 0.01) the STTD of P in corn germ from 40.7 to 59.0, 64.4, and 63.2%, respectively. Regression equations were developed to calculate the STTD of P in corn and corn germ, and R(2) values were 0.63 and 0.79, respectively. However, for DDGS and HP-DDG, the R(2) values were only 0.20 and 0.36, respectively, and these equations were, therefore, not considered adequate to predict the STTD of P. In conclusion, the increase in the STTD of P in corn and corn germ that is a result of microbial phytase can be predicted by regression equations, but microbial phytase has much less of an effect on the STTD of P in DDGS and HP-DDG and responses to addition of graded levels of phytase to these ingredients can, therefore, not be accurately predicted by regression equations.

Digestibility of amino acids in corn, corn coproducts, and bakery meal fed to growing pigs.

The objectives of this experiment were to determine the apparent ileal digestibility and the standardized ileal digestibility (SID) of CP and AA in bakery meal, corn gluten meal, corn gluten feed, corn germ meal, and hominy feed and to compare these values with the apparent ileal digestibility and SID of CP and AA in corn and distillers dried grains with solubles (DDGS). Eight growing barrows (initial BW: 82.5 ± 5.5 kg) were randomly allotted to an 8 × 8 Latin square design with 8 diets and 8 periods. Diets contained corn, DDGS, bakery meal, corn gluten meal, corn gluten feed, corn germ meal, or hominy feed as the sole source of protein and AA. An N-free diet was used to measure basal endogenous losses of AA and protein. Pigs were fed experimental diets for eight 7-d periods, with ileal digesta being collected on d 6 and 7 of each period. Results indicated that the SID of Lys in corn gluten meal (78.7%) was greater (P < 0.01) than in DDGS, bakery meal, corn germ meal, and hominy feed (46.0, 48.4, 68.4, and 58.8%, respectively). The SID of all indispensable AA except Arg, Leu, and Met in bakery meal were not different from those in DDGS. The SID of Arg, His, Leu, and Met in corn gluten feed were less (P < 0.01) than in corn, but the SID of all other indispensable AA in corn gluten feed were not different from those in corn. However, for most indispensable AA, the SID in corn gluten feed was not different from the SID in DDGS. The SID of all indispensable AA in corn germ meal, except Arg, His, Leu, and Met, were not different from the SID in corn. Likewise, the SID of all indispensable AA in corn germ meal, except Arg and Leu, were not different from those in DDGS. The SID of Ile, Met, Phe, and Val in hominy feed were less (P < 0.01) than in corn, but the SID of the remaining indispensable AA in hominy feed were not different from the SID of indispensable AA in corn. All indispensable AA in hominy feed also had SID values that were not different from the SID values of AA in DDGS, except for Arg and Lys, which had greater (P < 0.01) SID than in DDGS. In conclusion, bakery meal had SID values of most AA that were less than in corn, but corn gluten meal had SID values for most AA that were greater than the SID of AA in corn, bakery meal, and corn coproducts.

Performance and phosphorus balance of pigs fed diets formulated on the basis of values for standardized total tract digestibility of phosphorus.

Three experiments were conducted to test the hypotheses that pigs fed diets that are equal in digestible P will perform equally regardless of the concentration of total P in the diets, and that the addition of microbial phytase, distillers dried grains with solubles (DDGS), or a combination of phytase and DDGS will result in a reduction in P excretion. In Exp. 1, a P-free diet and 6 diets containing corn, soybean meal (SBM), or DDGS without or with microbial phytase (500 phytase units per kg) were formulated. Diets were fed for 12 d to 42 pigs (initial BW = 13.5 +/- 3.9 kg) housed in metabolism cages that allowed for total collections of feces. Basal endogenous P losses were determined to be 199 mg/kg of DMI for pigs fed the P-free diet. Addition of phytase increased (P < 0.01) the standardized total tract digestibility (STTD) of P in corn (64.4 vs. 26.4%) and SBM (74.9 vs. 48.3%), but there was no effect (P > 0.10) of the addition of phytase on the STTD of P in DDGS (75.5 vs. 72.9%). In Exp. 2, a total of 160 pigs (initial BW = 11.25 +/- 1.95 kg; 4 pigs/pen) were allotted to 4 corn- and SBM-based diets with 2 amounts of phytase (0 or 500 phytase units per kg) and 2 amounts of DDGS (0 or 20%) in a 2 x 2 factorial arrangement of treatments. All diets were formulated to contain 0.32% STTD of P according to the STTD values determined in Exp. 1. Diets were fed for 21 d and results indicated that inclusion of phytase in the diet containing no DDGS tended (P < 0.10) to decrease G:F, but inclusion of 20% DDGS in the diets tended (P < 0.10) to increase ADG, ADFI, and final BW. In Exp. 3, the diets used in Exp. 2 were fed to 24 pigs (initial BW = 14.6 +/- 1.4 kg) that were placed in metabolism cages individually. Feces and urine were collected for 5 d. Phytase and DDGS increased (P < 0.01) the apparent total tract digestibility of P in the diets. Absorption of P was greater (P < 0.05) in pigs fed corn-SBM-DDGS diets than pigs fed corn-SBM diets, and phytase, DDGS, or the combination of phytase and DDGS reduced (P < 0.01) P excretion. In conclusion, the addition of phytase increased the STTD of P in corn and SBM, but had no effect on the STTD of P in DDGS. Diets may be formulated based on STTD values without compromising pig performance, and dietary phytase, DDGS, or the combination of phytase and DDGS will reduce P excretion by growing pigs.