True Total Tract Digestibility Research Articles

182 True total-tract digestibility of calcium in limestone and dicalcium phosphate for twenty-kilogram pigs are additive in a semi-purified diet

182 True total-tract digestibility of calcium in limestone and dicalcium phosphate for twenty-kilogram pigs are additive in a semi-purified diet

Methodological aspects of determining phosphorus digestibility in swine: A review.

The role of phosphorus (P) in swine nutrition has been taken on new significance in recent years. Methods to determine the available phosphorus (AP) content of swine feeds include relative bioavailability (RBV), apparent total tract digestibility (ATTD), standardized total tract digestibility (STTD), and true total tract digestibility (TTTD). The RBV of P is determined by measuring bone ash or bone P, whereas the ATTD of P is determined by calculating the difference between P intake and P excretion in feces. Recent research has shown that the use of ATTD of P underestimates the AP due to the existence of endogenous P in feces and digesta. The STTD can be calculated from ATTD by taking basal endogenous phosphorus losses (EPL) into consideration. The basal EPL in pigs can be measured by feeding a P-free diet. Values for STTD of P are believed to be additive in mixed diets but not for ATTD of P. The regression method is a common approach to determine total EPL and TTTD of P, which measures the linear relationship between fecal P excretion and the dietary intake of total P. In addition, in vitro methods such as the bionic enzymatic method are being increasingly utilized because they can be done quickly and simply. Several dietary factors such as P and Ca concentrations, phytate, Ca to P ratio and vitamin D may affect AP. This review summarizes the evolution of methods to measure AP and factors that can affect AP, which may provide information to formulate swine diet more accurately. Moreover, the knowledge about AP may help to reduce the P waste in swine production and thus decrease its impact on the environment.

Apparent and true ileal and total tract digestibility of fat in canola press-cake or canola oil and effects of increasing dietary fat on amino acid and energy digestibility in growing pigs

Apparent and true ileal and total tract digestibility of fat in canola press-cake or canola oil and effects of increasing dietary fat on amino acid and energy digestibility in growing pigs

Effect of phytase on true total tract digestibility of phosphorus in full-fat rice bran determined in pigs by regression method

The goal of this study was to determine the effect of phytase on true total tract digestibility of phosphorus (TTDP) and endogenous losses of phosphorus (ELP) of full-fat rice bran (FFRB) by simple linear regression. Twelve castrated pigs in the growing phase with an average live weight of 57.00 ± 2.50 kg were used. The experiment lasted 36 days, divided into three periods of 12 days each. The experimental design consisted of randomized blocks in a 2 × 3 factorial scheme, with two levels of fungal phytase (0 and 750 FTU $\mathbb{kg}^-1$ ) and three levels of phosphorus (P) coming from FFRB (5%, 10%, and 20%), totaling six treatments with six replicates. The P coming from FFRB recovered in feces was influenced by phytase (P < 0.008) and by the amount of ingested FFRB (P < 0.001). The average value of ELP was 524 mg/kg dry matter intake (DMI). The TTDP of FFRB was increased by 20 percentage points due to phytase addition. In conclusion, the ELP represented 524 mg/kg DMI on average. The addition of 750 FTU of phytase increased the TTDP of FFRB, which was 32.60% and 52.60% without and with phytase, respectively.

Endogenous fat loss and true total tract digestibility of poultry fat in adult dogs

Endogenous fat loss and true total tract digestibility of poultry fat in adult dogs

Does heat stress alter the pig's response to dietary fat?

Heat stress (HS) results in major losses to the pork industry via reduced growth performance and, possibly, carcass fat quality. The experimental objective was to measure the effects of HS on the pig's response to dietary fat in terms of lipid digestion, metabolism, and deposition over a 35-d finishing period. A total of 96 PIC 337 × C22/C29 (PIC, Inc., Hendersonville, TN) barrows (initial BW of 100.4 ± 1.2 kg) were randomly allotted to 1 of 9 treatments arranged as a 3 × 3 factorial: thermoneutral (TN; constant 24°C; ad libitum access to feed), pair-fed thermoneutral (PFTN; constant 24°C; limit fed based on previous HS daily feed intake), or HS (cyclical 28°C nighttime, 33°C from d 0 to 7, 33.5°C from d 7 to 14, 34°C from d 14 to 21, 34.5°C from d 21 to 28, and 35°C from d 28 to 35 daytime; ab libitum access to feed) and diet (a corn-soybean meal-based diet with 0% added fat [CNTR], CNTR with 3% added tallow [TAL; iodine value {IV} = 41.8], or CNTR with 3% added corn oil [CO; IV = 123.0]). No interactions between environment and diet were evident for any major response criteria ( ≥ 0.063). Rectal temperature increased due to HS (39.0°C for HS, 38.1°C for TN, and 38.2°C for PFTN; < 0.001). Heat stress decreased ADFI (27.8%; < 0.001), ADG (0.72 kg/d for HS, 1.03 kg/d for TN, and 0.78 kg/d for PFTN; < 0.001), and G:F (0.290 for HS, 0.301 for TN, and 0.319 for PFTN; = 0.006). Heat stress barrows required 1.2 Mcal of ME intake more per kilogram of BW gain than PFTN ( < 0.001). Heat stress tended to result in the lowest apparent total tract digestibility of acid hydrolyzed ether extract (AEE; 59.0% for HS, 60.2% for TN, and 61.4% for PFTN; = 0.055). True total tract digestibility (TTTD) of AEE of CO-based diets (99.3%) was greater than that of CNTR (97.3%) and TAL-based diets (96.3%; = 0.012). Environment had no impact on TTTD of AEE ( = 0.118). Environment had no impact on jowl IV at market (69.2 g/100 g for HS, 69.3 g/100 g for TN, and 69.8 g/100 g for PFTN; = 0.624). Jowl IV at market increased with increasing degree of unsaturation of the dietary fat (68.5 g/100 g for CNTR, 68.2 g/100 g for TAL, and 71.5 g/100 g for CO; < 0.001). Heat stress decreased mRNA abundance of and ( ≤ 0.041). Heat stress and CO increased mRNA abundance of ( ≤ 0.047), and CO increased abundance of ( = 0.011). In conclusion, HS does not alter the pig's response to dietary fat. However, HS leads to reduced ADG, ADFI, G:F, and caloric efficiency and a suppression of mRNA abundance of genes involved in the lipolytic cascade, which resulted in a phenotype that was fatter than PFTN.

Evaluation of available energy and total tract digestibility of acid-hydrolyzed ether extract of cottonseed oil for growing pigs by the difference and regression methods.

ObjectiveThe objective of this study was to determine the effect of inclusion level on the digestible energy (DE), metabolizable energy (ME), and total tract digestibility of acid-hydrolyzed ether extract (AEE) of cottonseed oil when fed to growing pigs.MethodsForty-two barrows (initial body weight = 35.51±2.01 kg) were randomly allotted to a completely randomized design with a corn-soybean meal basal diet, five levels of cottonseed oil (2%, 4%, 6%, 8%, and 10%) and a 10% soybean oil diet. Each diet was replicated six times with one pig per replicate. The experiment lasted 19 days, 7 d for cage adaptation, 7 d for diets adaptation and last 5 d for feces and urine collection. The energy values and apparent total tract digestibility (ATTD) of cottonseed oil and soybean oil were calculated by the difference method, and regression equations were established to predict the energy values of cottonseed oil. The apparent digested fat of the entire intestinal tract was also regressed against dietary fat intake to determine the true total tract digestibility (TTTD) and endogenous loss of fat for cottonseed oil.ResultsThe results showed that the DE and ME contents of cottonseed oil were not different as the inclusion level increased. The DE and ME values determined by the regression equation were 36.28 MJ/kg and 34.96 MJ/kg, respectively, and the values were similar to the mean DE and ME values calculated by the difference method (36.18 and 35.56 MJ/kg, respectively). The ATTD of cottonseed oil was also not affected by the inclusion level of cottonseed oil, and the TTTD and EFL determined by the regression method were 92.40% and 13.83 g/kg of dry matter intake for corn-soybean basal diet. The DE, ME, and ATTD of AEE in soybean oil determined by the difference method were 35.70 MJ/kg, 35.20 MJ/kg and 92.31%, respectively. There were no differences in the DE, ME, and ATTD between cottonseed oil and soybean oil, although the ratio of unsaturated to saturated fatty acids for soybean oil was higher than for cottonseed oil.ConclusionThe DE, ME, and ATTD values of cottonseed oil were not affected by its dietary inclusion level. The energy values of cottonseed oil determined by the difference and regression methods were similar. Furthermore, the ratio of unsaturated to saturated fatty acid for oils was not the decisive factor to influence the energy values and ATTD of oils.

Nutritive Value of Mulberry Leaf Meal and its Effect on the Performance of 35-70-Day-Old Geese.

Availability of feed crops for animal production is decreasing, creating a need to identify alternative food sources. With their high protein content, mulberry leaves are a likely candidate for feed supplementation and have been trialed on pigs and chickens, but little is known about their effect as a feed supplement on geese. Here, we determine the nutritive value of mulberry leaf meal (MLM), measure the digestibility of energy and amino acid of MLM in male Sichuan white geese, and evaluate the performance of these geese fed an MLM-supplemented diet. The composition of MLM was as follows: gross energy 4.94 Mcal/kg, crude protein 18.81%, ether extract 11.65%, crude fiber 12.45%, calcium 2.46%, phosphorous 0.24% and amino acids 0.26–1.92% (all % on a dry matter basis). Using the emptying then force-feeding method on 24 geese aged 194 days, we measured the apparent metabolizable energy of MLM as 1.58 Mcal/kg (on a dry matter basis), and the true total tract digestibility of the amino acids in MLM as 50.54–79.98%. We then randomly allocated a further 210 geese aged 35 days to one of five dietary treatments (control diet alone or supplemented with 4%, 8%, 12% or 16% MLM). Each treatment contained six replicate pens of seven birds per pen, and birds were maintained on their treatment until 70 days of age. Geese fed diets containing MLM exhibited lower weight gains, elevated feed consumption and an increased feed to gain ratio (P<0.05) compared with geese fed the control diet. Moreover, geese fed diets supplemented with MLM all experienced diarrhea, reduced amounts of subcutaneous fat and lower percentages of skin and abdominal fat (P<0.05) compared with control geese. In conclusion, MLM should be used with caution as a feed supplement for geese.

Effects of distillers' dried grains with solubles and soybean oil on dietary lipid, fiber, and amino acid digestibility in corn-based diets fed to growing pigs.

The use of corn coproducts increases the concentration of fiber and, often, the use of supplemental lipids in swine diets, which may affect energy and nutrient digestibility. An experiment was conducted to determine the effects of reduced-oil distillers' dried grains with solubles (DDGS) and soybean oil (SBO) on dietary AA, acid hydrolyzed ether extract (AEE), and NDF digestibility in corn-based diets fed to growing pigs. Eighteen growing pigs (33.8 ± 2.2 kg BW) were surgically fitted with a T-cannula in the distal ileum and allocated to 1 of 6 dietary treatment groups in a 3-period incomplete Latin square design, with 9 observations per treatment. Six dietary treatments were obtained by adding 0, 20, and 40% DDGS to corn-casein diets formulated with 2 and 6% SBO. Ileal digesta and fecal samples were collected and the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of AEE and NDF and the AID of AA were determined. Apparent values were corrected for endogenous losses of lipids, and true ileal (TID) and true total tract digestibility (TTTD) values of lipids were calculated. Results showed that the AID of Lys decreased ( < 0.001) with the inclusion of DDGS but was not affected ( = 0.63) by the inclusion of SBO. An interaction between DDGS and SBO on the AID ( = 0.002) and ATTD ( = 0.009) of NDF was observed, where the AID and ATTD of NDF decreased with DDGS at 6% SBO but no effect was observed at 2% SBO. The AID of NDF increased with SBO at 0% DDGS, but no effect was observed at 20 or 40% DDGS. An interaction between DDGS and SBO on the AID ( = 0.011) and ATTD ( = 0.008) of AEE was observed, where the AID and ATTD of AEE increased with SBO. The AID and ATTD of AEE increased with DDGS at 2% SBO, but no effect was observed at 6% SBO. Correction by ileal and fecal endogenous loss of AEE (9.5 and 13.6 g/kg of DMI, respectively) showed that increasing dietary AEE had no effect on the TID and TTD of AEE ( > 0.05). In conclusion, the AID of Lys decreased with DDGS and was not affected by lipids from SBO. The greatest AID and ATTD of NDF was observed in diets with a high AEE and low NDF content. Low values of apparent digestibility of AEE in lower-lipid diets are possibly the result of endogenous losses of lipids, because the true digestibility of AEE was not affected by the dietary increase of AEE.

222 Impact of the source and level of dietary fat on growth performance as well as apparent and true total tract digestibility of acid hydrolyzed ether extract in growing and finishing pig diets

222 Impact of the source and level of dietary fat on growth performance as well as apparent and true total tract digestibility of acid hydrolyzed ether extract in growing and finishing pig diets

305 Does heat stress alter the pig's response to dietary fat source, as it relates to apparent or true total tract digestibility of dietary lipids?

305 Does heat stress alter the pig's response to dietary fat source, as it relates to apparent or true total tract digestibility of dietary lipids?

Effect of dietary phosphorus level on the determination of standardized and true total tract digestibility of phosphorus for growing pigs

The current study was conducted to investigate the effect of dietary phosphorus (P) concentration on the estimation of standardized total tract digestibility (STTD) and true total tract digestibility (TTTD) of P for growing pigs fed corn- and soybean meal (SBM)-based diets. Fifty-six barrows with an average initial BW of 30.9kg were used in a randomized complete block design with 7 diets. The 7 diets included a P-free diet and 6 corn- and SBM-based diets that contained the assay ingredient of 150, 300, 450, 600, 750, and 900g/kg. The assay ingredient consisted of corn and SBM at a fixed ratio of 3:2 by weight. The P-free diet was used to estimate endogenous P loss (EPL) of pigs and to calculate STTD of P in the assay ingredient. The total collection procedure was used to calculate P digestibility with a 5-days adjustment period followed by a 7-days collection period using chromic oxide as a marker to indicate the initiation and termination of fecal collection. The results showed that daily P intake, fecal P output, digested P, and retained P increased linearly with increasing dietary P level for pigs fed corn- and SBM-based diets (P<0.01). Apparent total tract digestibility (ATTD) of P, urinary P output, and P retention were not affected by dietary P content (P>0.05). There was a linear decrease in STTD of P (from 54.13 to 43.42%) with graded inclusion of dietary P (P<0.01). Regressing daily digested P against daily P intake, the TTTD of P were estimated at 40.24 and 38.22% for pigs fed low P diets (the assay ingredient level at 150, 300, and 450g/kg) and high P diets (the assay ingredient level at 600, 750, and 900g/kg), respectively. The estimates of TTTD of P were not statistically different between pigs fed low P diets and high P diets (P>0.05). In conclusion, increasing dietary P from graded inclusion of the assay ingredient reduced the estimated values of STTD of P but did not affect the estimates of TTTD of P determined by the regression method.

Casein Supplementation Does Not Affect the Estimates of True Total Tract Digestibility of Phosphorus in Soybean Meal for Growing Pigs Determined by the Regression Method.

Forty-eight barrows with an average initial body weight of 25.5±0.3 kg were assigned to 6 dietary treatments arranged in a 3×2 factorial of 3 graded levels of P at 1.42, 2.07, or 2.72 g/kg, and 2 levels of casein at 0 or 50 g/kg to compare the estimates of true total tract digestibility (TTTD) of P in soybean meal (SBM) for pigs fed diets with or without casein supplementation. The SBM is the only source of P in diets without casein, and in the diet with added casein, 1.0 to 2.4 g/kg of total dietary P was supplied by SBM as dietary level of SBM increased. The experiment consisted of a 5-d adjustment period and a 5-d total collection period with ferric oxide as a maker to indicate the initiation and termination of fecal collection. There were interactive effects of casein supplementation and total dietary P level on the apparent total tract digestibility (ATTD) and retention of P (p<0.05). Dietary P intake, fecal P output, digested P and retained P were increased linearly with graded increasing levels of SBM in diets regardless of casein addition (p<0.01). Compared with diets without casein, there was a reduction in fecal P in the casein-supplemented diets, which led to increases in digested P, retained P, ATTD, and retention of P (p<0.01). Digested N, ATTD of N, retained N, and N retention were affected by the interaction of casein supplementation and dietary P level (p<0.05). Fecal N output, urinary N output, digested N, and retained N increased linearly with graded increasing levels of SBM for each type of diet (p<0.01). The estimates of TTTD of P in SBM, derived from the regression of daily digested P against daily P intake, for pigs fed diets without casein and with casein were calculated to be 37.3% and 38.6%, respectively. Regressing daily digested N against daily N intake, the TTTD of N in SBM were determined at 94.3% and 94.4% for diets without casein and with added casein, respectively. There was no difference in determined values of TTTD of P or N in SBM for pigs fed diets with or without casein (p>0.05). In summary, our results demonstrate that the estimates of TTTD of P in SBM for pigs were not affected by constant casein inclusion in the basal diets.

True digestible phosphorus requirement for forty- to eighty-kilogram pigs.

The objective of this study was to determine the true digestible P requirement of 40- to 60-kg (Exp. 1) and 60- to 80-kg (Exp. 2) pigs by broken-line analysis of growth performance data using 6 levels of true digestible P. In each 3-wk experiment, 108 barrows and gilts were used, and 6 levels of monocalcium phosphate were added to a corn-soybean meal-based diet to establish 6 graded levels of true total tract digestible P ranging from 1.26 to 3.98 g/kg of diet in Exp. 1 or from 1.21 to 3.31 g/kg in Exp. 2. The true digestible P content was calculated using true total tract digestibility of 40.53%, 35.96%, and 84.31% for P in corn, soybean meal, and monocalcium phosphate, respectively. Limestone was added accordingly to maintain a constant Ca level across all diets of each experiment. The results of Exp. 1 showed that with graded supplementation of monocalcium phosphate, ADG linearly increased ( < 0.001) in wk 1 and both linearly and quadratically increased ( < 0.01) in wk 2, wk 3, and wk 0 to 3, and G:F linearly improved ( < 0.001) in wk 1, quadratically improved ( < 0.05) in wk 3, and both linearly and quadratically improved ( < 0.05) in wk 2 and wk 0 to 3 ( < 0.05). In Exp. 2, ADG linearly increased ( < 0.001) in wk 1 and both linearly and quadratically increased ( < 0.05) in wk 2, wk 3, and wk 0 to 3, with the graded supplementation of monocalcium phosphate, and G:F linearly improved ( < 0.01) in wk 1 and wk 3 and both linearly and quadratically improved ( < 0.001) in wk 2 and wk 0 to 3. In Exp. 1, the true digestible P requirement was estimated to be 2.66, 2.79, and 2.51 g/kg of diet (884 g DM/kg) for pigs of mixed sex, barrows, and gilts, respectively, on the basis of broken-line regression of ADG data for wk 0 to 3 against 6 true digestible P levels. Using G:F, the P requirement estimate was correspondingly 2.67, 2.51, and 2.93 g/kg of diet. In Exp. 2, the true digestible P requirement was estimated to be 2.29, 2.20, and 2.39 g/kg of diet (884 g DM/kg) using ADG data for wk 0 to 3 as the response variable and to be 2.33, 2.19, and 2.47 g/kg using wk 0 to 3 G:F data for pigs of mixed sex, barrows, and gilts, respectively. In conclusion, the mean TTTD-based P requirement was 2.66 and 2.31 g/kg of diet (884 g DM/kg) for 40- to 60-kg and 60- to 80-kg pigs, respectively.

Digestibility, ruminal fermentation and duodenal flux of amino acids in steers fed grass forage plus concentrate containing increasing levels of Acacia mearnsii tannin extract

Four Holstein steers (156±33kg of body weight (BW)) fitted with duodenal cannula and rumen catheter, were housed in metabolism pens and used in a 4×4 Latin square trial to evaluate the effect of dietary inclusion of levels of Acacia mearnsii tannin extract on rumen fermentation, digestion and duodenal flux of amino acids. The diet was offered at a restricted amount of 20g dry matter (DM)/kg BW and consisted of oat (Avena strigosa) plus concentrate, in a proportion of 0.55:0.45 (DM basis) respectively. Treatments were no tannin (Control) or inclusion of tannin extract in the concentrate at a rate of 20, 40 or 60g/kg DM (i.e. 9, 18 or 27g/kg of total dietary DM). The apparent total-tract organic matter (OM) digestibility was not affected whereas the neutral detergent fiber (aNDF) digestibility and the OM true total-tract digestibility tended to linearly decrease (P<0.10) at increased levels of tannin extract inclusion. Tannin extract linearly reduced (P<0.05) the total-tract digestibility of N compounds, as well as the urinary N excretion, and linearly increased (P<0.05) the fecal N excretion, N retention and the efficiency of N utilization by steers. The ruminal pH was similar for all treatments whereas the concentration of ammonia N and reducing sugars in ruminal fluid linearly decreased (P<0.05) with tannin extract inclusion. Linear positive responses (P<0.05) to tannin treatments were observed for duodenal flux of total N, α-amino N and non-ammonia non-microbial N. The microbial N supply tended to be negatively affected (P<0.10) whereas both the ruminal OM digestibility and ruminal degradability of feed N compounds linearly decreased (P<0.05) with increasing tannin extract levels. The efficiency of ruminal microbial protein synthesis tended to increase quadratically (P<0.10) at increased levels of tannin extract. The dietary inclusion of tannin extract positively impacted (P<0.05) or tended to impact (P<0.10) the duodenal flux of all amino acid groups, as well as of most individual amino acids. The amino acid profile in duodenal digesta was more closely related to the profile in feed at increased tannin extract inclusion. In conclusion, dietary inclusion of Acacia mearnsii tannin extract up to a level of 18g/kg DM decreased the urinary N excretion and improved the amino acid supply in steers fed fresh-frozen oat forage plus concentrate without significantly affecting the total OM digestibility.

The effect of inclusion level and basal diet on the determination of the digestible and metabolisable energy content of soybean oil and its digestibility when fed to growing pigs

This experiment was conducted to determine the effect of inclusion level and type of basal diet on the digestible (DE) and metabolisable (ME) energy content of soybean oil and its digestibility when fed to growing pigs. Thirty-six barrows (Duroc × Landrace × Yorkshire weighing 34.2 ± 3.8 kg) were randomly allotted to a 2 × 3 factorial arrangement involving two basal diets and three levels of soybean oil (0%, 5% and 10%). One basal diet was based on corn and soybean meal. The other basal diet was based on corn starch and casein. The barrows were housed in individual metabolism crates to facilitate separate collection of faeces and urine, and were fed the assigned test diets at 4% of initial bodyweight per day. A 5-day total collection of faeces and urine followed a 7-day diet-adaptation period. The DE and ME contents of soybean oil were significantly affected by the dietary inclusion level (P &lt; 0.05), but not by the type of basal diet. The DE contents of soybean oil at the 5% and 10% inclusion level were 34.99 and 37.63 MJ/kg, respectively, for the corn–soybean meal basal diet and 33.72 and 35.21 MJ/kg, respectively, for the corn starch–casein basal diet. The respective corresponding values for ME were 33.91, 37.07, 33.06 and 34.83 MJ/kg. The DE values calculated from regression equation were 38.05 and 37.85 MJ/kg, respectively, for corn–soybean meal and corn starch–casein basal diet. The DE value calculated from regression equation was greater than the values determined from the difference method for corn starch–casein basal diet. The value of endogenous loss for acid-hydrolysed ether extract was greater (P &lt; 0.05) for corn–soybean meal basal diet than for corn starch–casein (13.06 g/kg of dry matter intake for corn–soybean meal basal diet and 1.37 g/kg of dry matter intake for corn starch–casein basal diet, respectively). The values of the true total tract digestibility and apparent total tract digestibility of soybean oil determined from the corn–soybean meal basal diet were not different from those determined from the corn starch–casein basal diet (true total tract digestibility: 97.1% and 95.4%; apparent total tract digestibility: 95.8% and 95.3%, respectively). In conclusion, the DE and ME values of soybean oil are affected by its inclusion level but not by basal diet. The type of basal diet did not affect the digestibility of soybean oil, but affected the endogenous loss of acid-hydrolysed ether extract for soybean oil.

The Effect of Inclusion Level of Soybean Oil and Palm Oil on Their Digestible and Metabolizable Energy Content Determined with the Difference and Regression Method When Fed to Growing Pigs.

This experiment was conducted to determine the effects of inclusion level of soybean oil (SO) and palm oil (PO) on their digestible and metabolism energy (DE and ME) contents when fed to growing pigs by difference and regression method. Sixty-six crossbred growing barrows (Duroc×Landrace×Yorkshire and weighing 38.1±2.4 kg) were randomly allotted to a 2×5 factorial arrangement involving 2 lipid sources (SO and PO), and 5 levels of lipid (2%, 4%, 6%, 8%, and 10%) as well as a basal diet composed of corn and soybean meal. The barrows were housed in individual metabolism crates to facilitate separate collection of feces and urine, and were fed the assigned test diets at 4% of initial body weight per day. A 5-d total collection of feces and urine followed a 7-d diet adaptation period. The results showed that the DE and ME contents of SO and PO determined by the difference method were not affected by inclusion level. The DE and ME determined by the regression method for SO were greater compared with the corresponding respective values for PO (DE: 37.07, ME: 36.79 MJ/kg for SO; DE: 34.11, ME: 33.84 MJ/kg for PO, respectively). These values were close to the DE and ME values determined by the difference method at the 10% inclusion level (DE: 37.31, ME: 36.83 MJ/kg for SO; DE: 34.62, ME: 33.47 MJ/kg for PO, respectively). A similar response for the apparent total tract digestibility of acid-hydrolyzed ether extract (AEE) in lipids was observed. The true total tract digestibility of AEE in SO was significantly (p<0.05) greater than that for PO (97.5% and 91.1%, respectively). In conclusion, the DE and ME contents of lipid was not affected by its inclusion level. The difference method can substitute the regression method to determine the DE and ME contents in lipids when the inclusion level is 10%.

Phosphorus digestibility response of growing pigs to phytase supplementation of triticale distillers' dried grains with solubles.

An experiment was conducted in growing pigs to determine the true total-tract digestibility (TTTD) of P in triticale distillers' dried grains with solubles (DDGS) with or without phytase using the regression method. Six diets were formulated in a 3 × 2 factorial arrangement, including 3 levels of triticale DDGS (300, 400, or 500 g/kg) and phytase (0 or 500 phytase units [FTU]/kg of diet). A total of 48 barrows (initial BW 22.2 ± 1.3 kg) were assigned to the 6 diets in a randomized complete block design. There was a 5-d adjustment period followed by a 5-d total collection of feces. The results show that P intake, fecal P output, and digested P increased linearly ( < 0.01) with increasing level of DDGS in diets. There was a main effect ( < 0.001) of phytase on apparent total-tract digestibility (ATTD) of P. In diets without added phytase, the ATTD of P in triticale DDGS was 65.0, 67.7, and 63.2% for the diets with 300, 400, and 500 g/kg triticale DDGS, respectively; the corresponding values for diets with added phytase were 77.3, 76.3, and 75.7%. By regressing daily digested P against daily P intake, the TTTD of P was estimated at 75.4% for triticale DDGS or 81.1% with added phytase, respectively. In conclusion, the TTTD of P in triticale DDGS without supplemental phytase was 75.4%, and it was 81.1% in the presence of phytase at 500 FTU/kg of the diet, but the difference was not statistically significant. For triticale DDGS, the supplementation of 500 FTU/kg phytase in diet could increase the ATTD of P ( < 0.001) but not the TTTD of P.

Effect of feeding level on ileal and total tract digestibility of nutrients and energy from soybean meal‐based diets for piglets

A total of 36 piglets with an initial body weight (BW) of 5.6 ± 0.7 kg, fitted with simple T-cannulas at the distal ileum, were used to evaluate the effect of three graded feeding levels (50, 75 or 100 g/kg BW(0.75) day) on apparent ileal digestibility (AID) and total tract digestibility (ATTD) of dry matter (DM), nitrogen (N) and energy, and on ATTD of organic matter (OM), ether extracts (EE), neutral detergent fibre (NDF), acid detergent fibre (ADF) and digestible (DE), metabolisable (ME) and net energy (NE) content in soybean meal (SBM)-casein-cornstarch-based diets. The AID of DM, N and energy and ATTD of NDF, ADF and EE in the diets were not affected (p > 0.05) by the feed intake (FI) level. There was a small decrease in ATTD of DM, N (CP), OM, ash and energy, and in DE, ME and NE content in the diets (p < 0.05) with increasing FI level. The net disappearance in the large intestine (in % of ileal recovery) decreased for DM, N and energy (p < 0.05) with increasing FI level. The design of the study allowed for estimating ileal endogenous loss of N and total tract endogenous loss of ash, N and EE, for estimating corresponding true ileal and total tract digestibility values, and for estimating urinary endogenous N loss. High variability in estimates of ileal endogenous N loss and total tract endogenous losses of N, EE and ash reflects great variation in individual endogenous losses between animals. Estimation of true total tract digestibility of N, EE and ash by regression analysis was affected by their decrease in ATTD with increasing FI level, as estimates for true digestibility were lower compared to their apparent values. The present results suggest that FI level can affect both apparent and true total tract nutrient digestibility in piglets.

True digestible phosphorus requirement for twenty- to forty-kilogram pigs

The objective of this study was to determine the true digestible P requirements of 20- to 40-kg pigs by the broken-line regression analysis of growth performance using 6 levels of true total-tract digestible P. In Exp. 1, 24 barrows (initial BW=25.2±1.0 kg) were used to determine the true total-tract digestibility (TTTD) of P in monocalcium phosphate using the regression method. The dietary treatments included a corn-soybean meal-based diet (2.96 g total P/kg) and 3 additional dietary treatments with incremental addition of 0.50 g P/kg through monocalcium phosphate. Limestone (37.2% Ca) was added to maintain a constant Ca to P ratio of 1.25 to 1 across all diets. A 5-d adjustment period preceded a 5-d total collection of feces. Ferric oxide was used as a marker to time the initiation and termination of fecal collection. In Exp. 2, 108 barrows and gilts (initial BW=20.1±1.2 kg) were used in a 3-wk growth performance trial. Monocalcium phosphate was added to a corn-soybean meal-based diet to set up 6 levels of TTTD-based digestible P, ranging from 1.31 to 4.64 g/kg of diet with increments of 0.67 g/kg digestible P. Limestone was added to maintain a constant Ca level across all diets. The results of Exp.1 showed that dietary P intake, fecal P output, digested P, and apparent total-tract digestibility of P increased linearly (P<0.05) with the increasing supplementation of monocalcium phosphate. Regressing daily digested P against daily P intake resulted in TTTD of 84.3% for P in monocalcium phosphate. In Exp. 2, ADG, ADFI, and G:F increased both linearly (P<0.01) and quadratically (P<0.05) with increasing P level in wk 1 and 3 and for the overall 3-wk duration. In wk 2, both linear and quadratic effects of P level were observed for ADG and ADFI (P<0.05) whereas the G:F only showed linear improvement (P<0.01). The true digestible P requirement, defined as the breakpoint using the overall 3-wk G:F as the response variable, was estimated to be 3.03, 2.98, and 3.08 g/kg of diet for pigs of mixed sex, barrows, and gilts, respectively. Using ADG, the corresponding estimates of P requirement were 3.09, 3.08, and 3.10 g/kg of diet. In conclusion, the mean true digestible P requirement of pigs from 20 to 40 kg BW was determined to be 3.06 g/kg of diet using the average of the estimates for barrows and gilts based on ADG.