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Objective: The objective was to investigate the effects of dietary benzoic acid (BA) on nitrogen (N) balance, urinary pH, slurry pH, and odorous compounds in feces and slurry of pigs. Methods: Twelve barrows with an initial body weight of 56.2±2.6 kg were individually housed in metabolism crates. The animals were allocated to a replicated 6×4 incomplete Latin square design with 12 animals, 6 experimental diets, and 4 periods, resulting in 8 observations per treatment. The basal diet consisted mainly of corn, soybean meal, and rapeseed meal. Benzoic acid was supplemented to the basal diet at 0.5%, 1.0%, 1.5%, 2.0%, or 2.5% at the expense of corn starch. Each period consisted of a 4-day adaptation period and a 24-h collection period for slurry, followed by a 4-day collection period for feces and urine. On day 5, feces and urine were collected for 24 h and mixed to obtain slurry samples. Results: The daily digested N linearly increased (p<0.05) with increasing BA supplementation. Supplemental BA lowered urinary pH (p<0.001) and slurry pH (p<0.05) in a linear and quadratic manner. In the fecal samples, the concentrations of acetate, propionate, butyrate, and skatole linearly decreased (p<0.05) with supplemental BA. In the slurry samples, the concentrations of butyrate, isovalerate, and skatole linearly decreased (p<0.05) by supplemental BA. Conclusion: In conclusion, supplemental benzoic acid has the potential to improve nitrogen digestion in a dose-dependent manner for pigs. Additionally, dietary benzoic acid lowers urinary pH, slurry pH, and concentrations of odorous compounds in pig feces and slurry. [ABSTRACT FROM AUTHOR]

Simple Summary: Ammonia gases are produced from urea in the urine and slurry due to the action of urease. Odorous compounds are produced by microbial fermentation that utilizes an undigested nutrient in pig slurry. Various additives have been researched to mitigate ammonia emissions or odorous compound production. These studies involve inducing acidic conditions in urine or slurry, enhancing nitrogen utilization, inhibiting urease, or absorbing odorous compounds in pig slurry. However, information about the comparison of these additives is lacking. In this study, we evaluate and compare the effects of each additive on nitrogen utilization, urinary pH, slurry pH, and odorous compound concentrations. The five experimental diets were (1) a control diet, (2) the control diet with 1% benzoic acid, (3) the control diet with 1% adipic acid, (4) the control diet with 1% bromelain, and (5) the control diet with 1% humic substances. Fecal dry matter and nitrogen output were greatest in pigs fed the humic substances diet. Daily retained nitrogen and the nitrogen retention rate tended to be lowest in pigs fed an adipic acid diet. Urinary pH was lowest in pigs fed the adipic acid diet. In addition, slurry pH did not affect odorous compound concentrations, and some odorous compounds tended to be lowest in pigs fed the humic substances diet. The objective was to evaluate the effects of benzoic acid, bromelain, adipic acid, and humic substance supplementation on nitrogen balance, urinary pH, slurry pH, and manure odorous compounds in pigs. Fifteen castrated male pigs with an initial body weight of 37.9 kg (standard deviation = 4.1) were individually housed in metabolism crates. The animals were allocated to a triplicated 5 × 2 incomplete Latin square design with 15 animals, 5 experimental diets, and 2 periods. The basal diet mainly consisted of corn, soybean meal, and rapeseed meal. Four experimental diets were prepared by supplementing each additive at a concentration of 10 g/kg at the expense of corn starch to the basal diet. Each period consisted of a 4-day adaptation period, a 24 h collection period for slurry sampling, and a 4-day collection period for feces and urine. The feces and urine collected for 24 h on day 5 were mixed at a ratio of fecal weight and urine weight to obtain slurry samples. The apparent total tract digestibility N in pigs fed the humic substance diet was the least (p < 0.05) compared to the other groups. The daily retained N and N retention as % ingested tended (p < 0.10) to be the lowest in the adipic acid group among the treatments. The urinary pH in pigs fed the adipic acid diet was less (p < 0.05) than that in other groups except the benzoic acid group. The slurry pH tended to differ among the treatment groups (p = 0.074) with the lowest value in the pigs fed the adipic acid diet. The concentrations of indole in slurry (p = 0.084) and isovalerate in feces (p = 0.062) tended to differ among the groups with the lowest values in the pigs fed the humic substance diet. In conclusion, adipic acid supplementation in pig diets can decrease urinary pH and slurry pH. Although benzoic acid and adipic acid have limited effects in reducing odorous compounds, humic substances have the potential to reduce some odorous compounds. [ABSTRACT FROM AUTHOR]

Simple Summary: Black soldier fly larva meal is considered a promising protein source due to its high concentration of protein. A disinfection process is necessary to produce black soldier fly larva meal, because the black soldier fly is generally reared in food wastes or livestock manure. Drying methods include microwave drying, hot-air drying, and sun drying. Additionally, blanching as a pretreatment is also used to destroy microorganisms. However, information on the effect of these methods on nutrient utilization of black soldier fly larva meal by pigs is scarce. In the present study, the effects of drying and blanching methods on nutrient utilization were measured based on in vitro assays. Microwave-dried black soldier fly larva meal had less nitrogen digestibility than hot-air-dried black soldier fly larva meal. However, microwave-dried black soldier fly larva meal had greater nitrogen digestibility than blanched black soldier fly larva meal. The present study suggested that hot-air drying is recommended to produce black soldier fly larva meal based on the nutrient digestibility of black soldier fly larva meal for pigs. The objective was to determine the effects of drying and blanching methods on the nutrient utilization of black soldier fly larva (BSFL; Hermetia illucens) meal by pigs using in vitro assays. Two-step and three-step in vitro assays were employed to simulate the gastrointestinal tract of pigs. Four BSFL meals were prepared using the following pretreatment methods: (1) microwave drying at 80 °C for 32 min, (2) hot-air drying at 60 °C for 17 h, (3) blanching for 5 min in boiling water and hot-air drying at 60 °C for 17 h, and (4) 2% citric acid solution blanching for 5 min in boiling solution and hot-air drying at 60 °C for 17 h. After the drying process, each BSFL was defatted and ground to obtain BSFL meals. The nitrogen (N) concentration in the test ingredients ranged from 8.5 to 9.4%, and the ether extract ranged from 6.9 to 11.5% on an as-is basis. The amino acid (AA) concentration in the BSFL meals ranged from 2.80 to 3.24% for Lys and 0.71 to 0.89% for Met on an as-is basis. Hot-air-dried BSFL meal had a greater in vitro ileal disappearance (IVID) of N compared with microwave-dried BSFL meal (p < 0.05). However, blanched BSFL meals in water or 2% citric acid solution before hot-air drying had a lower (p < 0.05) IVID of N compared with microwave-dried or hot-air-dried BSFL meal. Blanched BSFL meals in water or 2% citric acid solution before hot-air drying showed a lower (p < 0.05) in vitro total tract disappearance of dry matter and organic matter compared with microwave-dried or hot-air-dried BSFL meal. Microwave-dried BSFL meal had a lower (p < 0.05) IVID of indispensable AA, except for His, Lys, Met, and Phe, compared with hot-air-dried BSFL meals. However, blanched BSFL meals in water or 2% citric acid solution before hot-air drying showed a lower (p < 0.05) IVID of indispensable AA compared with microwave-dried or hot-air-dried BSFL meal. In conclusion, hot-air-dried BSFL meal presented greater nutrient utilization compared with microwave-dried BSFL meal for pigs. However, blanching in water or citric acid solution negatively affected the nutrient digestibility of BSFL meal based on in vitro assays. [ABSTRACT FROM AUTHOR]

The objectives were to determine the digestible energy (DE) and metabolizable energy (ME) concentrations in black solider fly (BSF; Hermetia illucens) larvae fed to pigs and to develop prediction equations for energy in BSF larvae. On a dry matter (DM) basis, 4 sources of defatted BSF larva meal contained 4,402 to 5,173 kcal/kg gross energy (GE), 46.5 to 62.0% crude protein (CP), 9.0 to 14.3% ether extract (EE), and 13.7 to 25.3% ash and a source of full-fat BSF larva contained 5,875 kcal/kg GE, 36.5% CP, 38.5% EE, and 16.3% ash. Six barrows with an initial body weight of 73.1 kg (SD = 2.3) were individually housed in metabolism crates. Six diets were assigned to the 6 pigs in a 6 × 7 Latin square design with 7 periods. A basal diet was composed of 97.6% corn as the sole energy source. Five experimental diets were prepared by replacing 25% of corn with BSF larva. Each period consisted of a 4-day adaptation period and a 4-day collection period for feces and urine collection. The DE and ME values in full-fat BSF larva (4,908 and 4,761 kcal/kg DM) were greater (P < 0.05) than those in defatted BSF larva meal (3,791 to 4,269 kcal/kg DM and 3,577 to 3,878 kcal/kg DM). Energy prediction models developed for BSF larva were: GE (kcal/kg DM) = 5,707 + 36.2 × EE - 74.2 × ash (R2 = 0.98); DE (kcal/kg DM) = 4,575 + 29.1 × EE - 47.9 × ash (R2 = 0.99); and ME (kcal/kg DM) = 3,852 + 36.5 × EE - 30.0 × ash (R2 = 0.99) where chemical components are expressed as % DM. Overall, full-fat BSF larva contained greater energy concentrations compared with defatted larva meal and energy concentrations in BSF larva ingredients can be estimated using EE and ash concentrations. [ABSTRACT FROM AUTHOR]

The objective was to determine the effects of different drying methods on nutrient utilization of black soldier fly (BSF; Hermetia illucens) larva meals using in vitro assays. Two-step and 3-step in vitro assays were employed to simulate the gastrointestinal tract of pigs. Four methods were used to obtain BSF larva meal sources: 1) microwave-drying for 32 min, 2) hot-air drying at 60°C for 17 h, 3) water blanching for 5 min and hot-air drying for 17 h, and 4) 2% citric acid solution blanching for 5 min and hot-air drying for 17 h. After the drying process, each BSF larva was defatted and ground to obtain BSF larva meals. The crude protein (CP) concentration in the test ingredients ranged from 54.7 to 60.4% on dry matter (DM) basis and ether extract ranged from 7.1 to 11.8% DM. Hot-air-dried BSF larva meal had greater in vitro ileal disappearance (IVID) of CP compared with microwave-dried BSF larva meal (86.7% vs. 84.4%; P < 0.05). However, blanching BSF larva in water or 2% citric acid solution before hot-air drying resulted in less IVID of CP (81.3 or 82.5%; P < 0.05) compared with microwave-dried or hot-air-dried BSF larva meal. Blanching BSF larva in water or 2% citric acid solution before hot-air drying resulted in less in vitro total tract disappearance of DM (85.0% or 84.5% vs. 90.4% or 89.6%; SEM = 0.3, P < 0.05) and OM (80.6% or 81.5% vs. 85.7% or 86.6%; SEM = 0.1, P < 0.05) compared with microwave-dried or hot-air-dried BSF larva meal. In conclusion, hot-air-dried BSF larva meal had greater nutrient utilization compared with microwavedried BSF larva meal. However, blanching BSF larva in water or citric acid solution negatively affected nutrient digestibility based on in vitro assays. [ABSTRACT FROM AUTHOR]

The objective of the present study was to develop prediction equations for digestible energy (DE) and metabolizable energy (ME) in swine diets based on chemical compositions of feces with no dietary information. A total of 262 fecal samples obtained from growing pigs fed 27 diets from 4 experiments were used. The diets were based mainly on corn, soybean meal, and other plant-originated feed ingredients. In the digestibility experiments, feces and urine were quantitatively collected using the marker-to-marker procedure. The diet and fecal samples were analyzed for dry matter (DM), crude protein, ash, and neutral detergent fiber (NDF). Digestible energy in the 27 diets ranged from 2,907 to 4,374 kcal/kg DM and ME ranged from 2,774 to 3,983 kcal/kg DM. Fecal ash was positively correlated with DE (r = 0.81, P < 0.001) and ME (r = 0.66, P < 0.001) whereas fecal NDF was negatively correlated with DE (r = -0.66, P < 0.001) and ME (r = -0.74, P < 0.001). The energy prediction equations developed using fecal chemical components were: energy digestibility = 88.1 + 0.37 × ash - 0.28 × NDF (R2 = 0.57, P < 0.001); DE (kcal/kg DM) = 3,604 + 32.8 × ash - 11.1 × NDF (R2 = 0.71, P < 0.001); and ME (kcal/kg DM) = 4,077 + 15.7 × ash - 18.1 × NDF (R2 = 0.63, P < 0.001) where chemical components are expressed as % DM. In conclusion, energy digestibility, DE values, and ME values in swine diets are correlated with fecal ash and NDF concentrations and the energy values can be predicted using fecal ash and NDF concentrations without dietary information. [ABSTRACT FROM AUTHOR]

Simple Summary: Mycotoxins in feeds can cause detrimental effects on the growth performance and health of pigs. One of the methods used to overcome the negative effects of mycotoxins in animal feeds is to add toxin sequestering agents to feed. The present work was conducted to determine the efficacy of mycotoxin sequestering agents using an in vitro method. All mycotoxin sequestering agents effectively bound to aflatoxin B1; only activated charcoal effectively sequestered deoxynivalenol; and a bentonite product, an aluminosilicate product, and activated charcoal effectively sequestered zearalenone. The objective of this study was to determine the efficacy of mycotoxin sequestering agents for aflatoxin B1 (AFB1), deoxynivalenol (DON), and zearalenone (ZEA) using an in vitro method. The twelve toxin sequestering agents tested were seven bentonite products (bentonite A, B, C, D, E, F, and G), two aluminosilicate products (aluminosilicate A and B), a heulandite product, an activated charcoal product, and a yeast cell wall product. A two-step in vitro procedure was employed to mimic the conditions of temperature, pH, and digestive enzymes in the stomach and small intestine of pigs. All mycotoxin sequestering agents tested were able to bind to AFB1 with a high efficacy (>92%). The DON sequestering rate of activated charcoal (99.1%) was greater (p < 0.05) than that of other products. The ZEA sequestering rate of bentonite F (97.0%), aluminosilicate A (99.6%), and activated charcoal (100.0%) was the greatest (p < 0.05) among the tested mycotoxin sequestering agents. Overall, most mycotoxin sequestering agents had the ability to bind to AFB1, but most products, except activated charcoal, failed to sequester DON and ZEA. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the digestible energy (DE) and metabolizable energy (ME) concentrations in high-fiber ingredients fed to growing pigs. Twelve barrows with an initial body weight of 57.5 kg (SD = 5.7) were individually housed in metabolism crates. A replicated 6 × 3 incomplete Latin square design with 12 animals, 6 experimental diets and 3 periods was employed. A basal diet was composed of 75.0% corn and 22.7% soybean meal (SBM) as the sole energy sources. Four experimental diets were prepared by replacing 40% of corn and SBM with soybean hulls (SH), corn gluten feed (CGF), wheat bran (WB), or rice bran (RB). An additional diet was prepared by replacing 10% of corn and SBM with cashew nut hulls (CNH). Each period consisted of a 4-d adaptation period and a 4-d collection period, and the marker-tomarker procedure was used for total collection of feces and urine. The DE and ME values in RB (3,969 and 3,936 kcal/kg DM) were greater (P < 0.05) than those in CGF (2,654 and 2,520 kcal/kg DM) and SH (2,492 and 2,541 kcal/kg DM) and the energy values in WB (3,162 and 3,118 kcal/kg DM) were not different from those in RB, CGF, or SH. The DE and ME values in CNH (350 and 572 kcal/kg DM) were less (P < 0.05) than those in all other test ingredients. In conclusion, energy concentrations in RB were greatest among the high-fiber test ingredients, whereas CNH had the lowest values. [ABSTRACT FROM AUTHOR]

The objectives of the present work were to assess the accuracy of previously published equations for predicting effects of deoxynivalenol (DON) on the growth performance changes of pigs and to update equations based on recently published data. A total of 59 data were employed for the validation of previously published equations. These data were used to update the equations. The REG and CORR procedures of SAS were used. In the present validation test, a linear bias was significant (p < 0.05), indicating that prediction errors were not consistent across the data ranges. The intercept for ΔFI (−7.75 ± 1.19, p < 0.01) representing a mean bias was less than 0, indicating that the predicted mean of ΔFI was greater than the measured mean of ΔFI. Dietary DON concentrations had negative correlations with ΔWG (r = −0.79; p < 0.01) and ΔFI (r = −0.71; p < 0.01). Updated prediction equations were: ΔWG = −5.93 × DON with r2 = 0.77 and ΔFI = −4.42 × DON with r2 = 0.68. In conclusion, the novel equations developed in this study might accurately predict effects of dietary DON on the performance changes of pigs. [ABSTRACT FROM AUTHOR]

Sufficient supply of dietary phosphorus (P) is critical for maximizing muscle and bone growth of pigs. The objective was to compare standardized total tract digestible (STTD) P requirements of growing pigs determined in the experiments and those estimated using modeling approach. Fifty-two experiments in the literature that empirically determined P requirements of pigs were employed. The basis for the determination of P requirements were growth performance (average daily gain or gain to feed ratio; n = 34) and bone development (n = 23). Based on the STTD P in the feed ingredients provided in NRC (2012) and ingredient composition used in the experiments, P requirements presented as total P, available P, and true total tract digestible P were converted to STTD P requirements. To obtain STTD P requirements (g/d) suggested by NRC (2012) for grow-finishing pigs (body weight > 20 kg), mean body weight and sex indicated in the experiments were input into the NRC model. The statistical model for comparing the empirical data with the NRC requirements included the basis for determining P requirements in the experiments as a fixed variable and body weight as a random variable. To quantify the deviations between NRC STTD P requirement estimates and empirically determined STTD P requirements, mean percentage difference was calculated. The STTD P requirements empirically determined based on growth performance were greater than the NRC STTD P requirement estimates (5.89 vs. 4.61 g/d, SEM = 0.27; P < 0.001). Moreover, the bone development-based STTD P requirements were greater than the NRC STTD P requirement estimates (6.63 vs. 4.46 g/d, SEM = 0.42; P < 0.001). In conclusion, the standardized total tract digestible P requirements suggested by the NRC are less than the experimentally determined requirements. [ABSTRACT FROM AUTHOR]

Sufficient supply of dietary phosphorus (P) is critical for maximizing muscle and bone growth of pigs. The objective was to compare standardized total tract digestible (STTD) P requirements of growing pigs determined in the experiments and those estimated using modeling approach. Fifty-two experiments in the literature that empirically determined P requirements of pigs were employed. The basis for the determination of P requirements were growth performance (average daily gain or gain to feed ratio; n = 34) and bone development (n = 23). Based on the STTD P in the feed ingredients provided in NRC (2012) and ingredient composition used in the experiments, P requirements presented as total P, available P, and true total tract digestible P were converted to STTD P requirements. To obtain STTD P requirements (g/d) suggested by NRC (2012) for grow-finishing pigs (body weight > 20 kg), mean body weight and sex indicated in the experiments were input into the NRC model. The statistical model for comparing the empirical data and the NRC requirements included the basis for determining P requirements in the experiments as a fixed variable and body weight as a random variable. To quantify the deviations between NRC STTD P requirement estimates and empirically determined STTD P requirements, mean percentage difference was calculated. The STTD P requirements empirically determined based on growth performance were greater than the NRC STTD P requirement estimates (5.89 vs. 4.61 g/d, SEM = 0.27; P < 0.001). Moreover, the bone development-based STTD P requirements were greater than the NRC STTD P requirement estimates (6.63 vs. 4.46 g/d, SEM = 0.42; P < 0.001). In conclusion, the standardized total tract digestible P requirements suggested by the NRC are less than the experimentally determined requirements. [ABSTRACT FROM AUTHOR]

Simple Summary: Currently, all pigs raised on intensive farms develop iron-deficiency anemia if they do not receive supplemental iron at birth. Weaning diets commonly contain high concentrations of iron, and the effect on the copper and zinc contents in pork is unknown. In this exploratory work, we determined the effect of excessive oral iron supplementation on the contents of these microminerals in pork. Surprisingly, we found that high iron doses of 3000 ppm reduced the zinc content of pork by 32–55%. The aim of this work was to determine in an exploratory manner the effect of excessive iron supplementation on iron, zinc, and copper contents in pork and pork offal. Pigs averaging 50 days in age and 15 ± 1.3 kg body weight were allocated to a control group (500 ppm dietary Fe) and a supplemental group (3000 ppm dietary Fe). After an iron supplementation period of 60 days, blood samples were analyzed to determine iron biomarkers, serum copper, and zinc contents. Animals were slaughtered to assess total iron, non-heme iron, heme iron, zinc, and copper contents in samples of nine meat cuts and some offal. Iron supplementation improved the iron status in pigs with increased hemoglobin and hematocrit, but did not affect serum levels of iron, zinc, and copper. Iron supplementation did not affect the heme and non-heme iron contents of the different meat cuts. Zinc contents decreased by 32–55% in meat cuts, where iron content increased in the liver, spleen, kidneys, and pancreas. No differences of zinc and copper were observed in offal samples. High concentrations of iron supplementation reduce zinc content in pork. [ABSTRACT FROM AUTHOR]

The objective of the present study was to determine energy concentrations and nutrient digestibility of high-fiber ingredients for pigs using in vitro and in vivo assays. In experiment 1, in vitro ileal and total tract disappearance of nutrients in soybean hulls, corn gluten feed, wheat bran, rice bran, and cashew nut testa were determined. Two-step and 3-step in vitro procedures were used to simulate the digestion of nutrients in the gastrointestinal tract of pigs. The coefficient of in vitro ileal disappearance of dry matter (DM) in rice bran was the greatest (P < 0.05) among the test ingredients followed by wheat bran, corn gluten feed, cashew nut testa, and soybean hulls. The coefficient of in vitro total tract disappearance of DM and organic matter in rice bran was also the greatest (P < 0.05) among the test ingredients followed by wheat bran, cashew nut testa, corn gluten feed, and soybean hulls. In experiment 2, in vivo energy values and nutrient digestibility of the same ingredients used in experiment 1 were determined. Twelve barrows with an initial body weight of 57.5 kg (standard deviation = 5.7) were assigned to 6 experimental diets in a replicated 6 × 4 incomplete Latin square design. A basal diet consisted of 750 g/kg corn and 227 g/kg soybean meal (SBM) as the sole energy sources. Four experimental diets were prepared by replacing 400 g/kg of corn and SBM with soybean hulls, corn gluten feed, wheat bran, or rice bran. An additional diet was prepared by replacing 100 g/kg of corn and SBM with cashew nut testa. Each period consisted of a 4-day adaptation period and a 4-day collection period. On an as-fed basis, digestible energy and metabolizable energy concentrations in soybean hulls (2198 and 2242 kcal/kg), corn gluten feed (2317 and 2227 kcal/kg), and wheat bran (2751 and 2679 kcal/kg) were less (P < 0.05) than those in rice bran (3503 and 3459 kcal/kg), but those were greater (P < 0.05) than those in cashew nut testa (352 and 519 kcal/kg). The coefficient of apparent total tract digestibility of DM in wheat bran was greater (P < 0.05) than that in corn gluten feed and cashew nut testa. In conclusion, energy values and nutrient digestibility in rice bran were the greatest among the high-fiber ingredients, whereas cashew nut testa had the lowest values based on the present in vitro and in vivo experiments. In vitro procedures can be a potential alternative method for determining energy digestibility of ingredients for pigs. • Hulls and brans from soybean, corn, wheat, rice, and cashew nut were tested. • Nutritional value was greatest in rice bran based on in vitro and in vivo assays. • Nutritional value was least in cashew nut testa based on in vivo assays. [ABSTRACT FROM AUTHOR]

The objectives of the present study were to develop prediction equations for digestible energy (DE), metabolizable energy (ME), and coefficient of energy digestibility (ED) of swine diets using fecal nutrients as independent variables without dietary information and to validate the prediction equations. A total of 262 fecal samples obtained from growing pigs fed 27 diets in 4 experiments were used to develop prediction equations for DE, ME, and ED. These equations were validated using 95 fecal samples obtained from growing pigs fed 12 diets in an additional experiment. The diets were based mainly on corn, soybean meal, and other plant-originated feed ingredients. In the digestibility experiments, feces and urine were quantitatively collected using the marker-to-marker procedure. Diet and fecal samples were analyzed for dry matter (DM), crude protein, ash, and amylase-treated neutral detergent fiber (aNDF). The DE of the 27 diets ranged from 12,164 to 18,301 kJ/kg DM and ME of 24 diets ranged from 11,603 to 16,657 kJ/kg DM. Coefficients of ED for the 27 diets ranged from 0.667 to 0.919. Fecal ash was positively correlated with DE (r = 0.81; P < 0.001), ME (r = 0.66; P < 0.001), and coefficient of ED (r = 0.67; P < 0.001) whereas fecal aNDF was negatively correlated with DE (r = –0.66; P < 0.001), ME (r = –0.74; P < 0.001), and coefficient of ED (r = –0.67; P < 0.001). The prediction equations developed using fecal nutrients were: DE (kJ/kg DM) = 15,077 + (13.72 × ash) – (4.65 × aNDF) (R2 = 0.71; P < 0.001); ME (kJ/kg DM) = 17,067 + (6.54 × ash) – (7.56 × aNDF) (R2 = 0.63; P < 0.001); and coefficient of ED = 0.881 + (0.00037 × ash) – (0.00028 × aNDF) (R2 = 0.57; P < 0.001) where nutrients are expressed as g/kg DM. Based on the regression analysis for validation of the equations, the prediction equations for DE and coefficient of ED using only fecal aNDF did not have mean bias or linear bias. In conclusion, DE values, ME values, and coefficient of ED for swine diets are correlated with fecal ash and aNDF concentrations and the energy values can be predicted using fecal ash and aNDF concentrations without dietary information. • Energy values in pig diets are correlated with fecal ash and fiber concentrations. • Energy digestibility is correlated with fecal ash and fiber concentrations. • Dietary energy values can be predicted using fecal ash and fiber concentrations. [ABSTRACT FROM AUTHOR]