True Total Tract Digestibility Research Articles

From sewage sludge ash to a recycled feed phosphate – digestibility of precipitated calcium phosphate in broiler chickens and growing pigs

Today, EU is largely (∼92%) dependent on the import of phosphates as most mines are located outside Europe. Because of the limited availability, phosphorus (P) is included on the list of Critical Raw Materials. Precipitated calcium phosphate (PCP) recovered from sewage sludge ash is a novel and sustainable option to replace mined P as raw material in feed phosphates, e.g. monocalcium phosphate (MCP) or dicalcium phosphate, but the digestibility has not yet been tested in vivo. The aim was therefore to determine PCP and MCP apparent ileal digestibility (AID) of P in broiler chickens and apparent (ATTD) and true (TTTD) total tract digestibility of P in growing pigs. A chicken study comprised 240 Ross 308 chickens that were housed in groups of eight from day 21 to day 28. Five diets were used, a basal diet and two test diets, which contributed either 0.075% (low) or 0.150% (high) additional P for each of the test sources (MCP and PCP). The basal and test diets were composed to achieve increasing levels of P and AID was calculated with regression analysis. In the pig study, eight individually housed pigs were used in a change-over study with two experimental periods. The pigs were fed a basal P-free diet in a preperiod to be able to estimate endogenous P losses and then two different diets in two periods using a change-over design, where MCP and PCP were the only P source, providing in total 0.33 (basal diet), 4.42 (MCP) and 3.53 (PCP) g kg-1P, respectively. The AID of P in PCP and MCP for chickens was 58.4 and 75.1% (P = 0.166). The ATTD and TTTD of P in PCP for pigs were 58.4 and 67.2%, respectively, which was lower (P < 0.001) than the corresponding values for MCP (82.1 and 89.1%), respectively. The digestibility of calcium (Ca) did not differ in the chicken diets with high inclusion levels of PCP and MCP (54.7 and 55.3%, respectively, P = 0.535), but was lower for PCP than MCP in the pig study (57.8 and 70.8% respectively, P = 0.001). In conclusion, the digestibility of P in PCP for chickens did not differ from conventional MCP, whereas for pigs, it was lower, but could be a viable alternative to other common sources of P.

Comparison of digestible and available phosphorus release values for a novel phytase determined with fecal phosphorus digestibility and bone mineralization in weaner pigs

The objective of this study was to compare digestible and available P release from phytase through measuring fecal P digestibility and bone mineralization. A total of 336 weaner pigs (7.4 ± 0.9 kg) were used in a randomized complete block design. Three diets were established by including 2.5 (control), 6.0 or 9.5 g/kg monocalcium phosphate (MCP) to establish the standard response curves. The other 4 diets included a novel phytase at 500, 1000, 2000 or 3000 phytase units (FYT)/kg feed to the control. Each diet was fed to 6 pens of 8 pigs each for 21 days. All diets included 3 g/kg TiO2, and fecal samples were collected on d 13–15 of trial. At the end, one pig per pen was sacrificed for the collection of tibias. The results showed that increasing supplementation of MCP linearly (P < 0.001) improved growth performance (body weight gain, feed intake and gain:feed and bone mineralization (percent bone ash and weights of dry bone, bone ash, and bone Ca and P). These parameters responded to the supplementation of phytase both linearly and quadratically (P < 0.01). Supplemental phytase or MCP increased apparent total tract digestibility (ATTD) of Ca and P as well as the amount of ATTD P, but reduced the ATTD Ca-to-ATTD P ratio both linearly and quadratically (P < 0.01). Both MCP and phytase linearly (P < 0.05) increased percent bone ash P. The true total tract digestibility (TTTD) coefficient of P in MCP was estimated to be 0.94 by regressing the ATTD P against the dietary P concentration. The available P release increased from 1.58 to 2.21, 1.77–2.62, 1.17–1.82 and 1.25–1.97 g/kg feed when body weight gain, gain:feed, percent bone ash and bone P weight were used as the response variables, respectively, with increasing phytase dose from 500 to 3000 FYT/kg feed, whereas the digestible P release by phytase calculated from ATTD coefficient of P increased from 1.05 to 1.99 g/kg feed. By multiplying the TTTD coefficient of MCP (0.94), the available P release values based on bone P weight were transformed to their equivalent digestible values of 1.18–1.86 g/kg feed. In conclusion, the available P release from phytase depends on the response variables. Using the TTTD coefficient of P in MCP to convert the available P release values to digestible P values for phytase did not generate comparable results as measured from ATTD coefficient of P.

Effect of Fiber Fermentation and Protein Digestion Kinetics on Mineral Digestion in Pigs.

Simple SummaryThere is increasing interest in improving nutrient utilization in pigs and poultry and thereby reduce nutrient excretion into the environment. The present review aims to provide an overview on interactions between fermentable substrates (e.g., starch, fiber, and protein) and selected minerals on nutrient digestion and absorption to determine nutritional solutions to maximize animal performance, principally in the grower–finisher phase. Using in vitro models, the site and rate (kinetics) of nutrient digestion or fermentation of a feed ingredient or diet can be estimated. However, for minerals, no standardized methodology to assess in vitro mineral digestion exists. In vivo, the diet total tract digestibility of phosphorus might be underestimated in diets with fermentable ingredients because of increased diet-specific endogenous phosphorus losses and requires further clarification to better calculate the true total tract digestibility of phosphorus in pigs. The quantification of fiber type, composition of fiber fractions within individual raw materials, their influence on digestion kinetics, and effects on digesta pH and nutrient solubility related to fermentation should be considered. In conclusion, applications of nutrient kinetic data should be considered as part of an integrated approach to support nutrient digestion and absorption in the gastrointestinal tract of pigs, thereby helping to reduce nutrient excretion.Nutrient kinetic data and the timing of nutrient release along the gastrointestinal tract (GIT), are not yet widely used in current feed formulations for pigs and poultry. The present review focuses on interactions between fermentable substrates (e.g., starch, fiber, and protein) and selected minerals on nutrient digestion and absorption to determine nutritional solutions to maximize animal performance, principally in the grower–finisher phase, with the aim of minimizing environmental pollution. For phosphorus (P), myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP6), copper (Cu), and zinc (Zn), no standardized methodologies to assess in vitro mineral digestion exist. The stepwise degradation of InsP6 to lower inositol phosphate (InsP) forms in the GIT is rare, and inositol phosphate4 (InsP4) might be the limiting isomer of InsP degradation in diets with exogenous phytase. Furthermore, dietary coefficients of standardized total tract digestibility (CSTTD) of P might be underestimated in diets with fermentable ingredients because of increased diet-specific endogenous P losses (EPL), and further clarification is required to better calculate the coefficients of true total tract digestibility (CTTTD) of P. The quantification of fiber type, composition of fiber fractions, their influence on digestion kinetics, effects on digesta pH, and nutrient solubility related to fermentation should be considered for formulating diets. In conclusion, applications of nutrient kinetic data should be considered to help enhance nutrient digestion and absorption in the GIT, thereby reducing nutrient excretion.

Phosphorus nutrition of growing pigs.

Phosphorus (P) is an essential nutrient for diverse biological processes, which aggregate to the animal's requirement for P, and nutritionists strive to meet this requirement accurately. The P demand for a growing pig comprises requirements for maintenance and tissue deposition. The P in feed ingredients, however, must be digested and absorbed before its ultimate partition between the 2 aforementioned requirement components. Phosphorus from various sources could behave differently during digestion and absorption, which results in their disparate bioavailability for pigs. The system of standardized total tract digestibility reflects true total tract digestibility of P and feed ingredient effects on specific endogenous P loss with relative ease of implementation, and this system guarantees satisfactory additivity in digestible P among the ingredients in a diet—the foundation for diet formulation. The basal endogenous P loss, which is much easier to measure than the specific endogenous P loss, is considered as part of the pig's maintenance requirement. With this arrangement, a digestibility framework is established both for measuring the P-providing capacity of various feed ingredients and for describing the pig's P requirement. This framework entails basic understanding of the function, digestion, absorption, excretion, and homeostasis of P as support pillars. Understanding the workings of this framework enables potential integration of factors such as environment conditions and disease status in future P requirement models. The current review discusses dietary sources, digestion, absorption, bioavailability and requirement of P for growing pigs to understand the status quo, revealing the points of consensus as well as those of debate, and to encourage further investigation to provide more clarity.

Effect of xylanase supplementation on nutrient and energy digestibility at three time periods in growing pigs fed diets based on corn or corn distillers dried grains with solubles

A digestibility trial was conducted to better understand how xylanase impacts diet utilization in pigs by measuring its impact on the digestibility of energy, nitrogen, fat, fiber, and starch in the small and large intestine and across the total tract at three collection periods. Thirty-two 16-week-old gilts (DNA 600 [DNA Genetics, Columbus, NE, USA] × C22 [PIC Inc., Hendersonville, TN, USA]) were surgically fitted with T-cannulae at the terminal ileum, housed individually, and assigned to 1 of 4 dietary treatments in a completely randomized design, providing 24 observations per treatment Diets were arranged in a 2 × 2 factorial:0 vs 165 mg xylanase/kg (27,225 birch xylan units (BXU)/kg) of finished feed to corn-soybean meal diets and 0 g/kg (lower fiber: LF) vs 300 g/kg (higher fiber: HF) corn distillers’ dried grains with solubles (DDGS). Prior to surgery, the body weight (BW) of the pigs averaged 37.3 ± 0.8 kg. Three collection periods consisting of a 2-day fecal collection followed by a 3-day ileal collection occurred at day 9–13, 19–23 and 39–43 when pigs averaged 46.0 ± 0.4, 54.1 ± 0.4, and 70.3 ± 0.5 kg, respectively. Ileal and fecal samples were analyzed to determine the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of gross energy (GE), dry matter (DM), neutral detergent fiber assayed with heat stable amylase (aNDF), acid detergent fiber (ADF), and nitrogen (N), and the AID of starch and amino acids (AA). Apparent fat digestibility values were corrected for endogenous losses and reported as true ileal digestibility (TID) and true total tract digestibility (TTTD). Xylanase inclusion tended to decrease AID of aNDF and decreased ADF in LF diets, but had no impact in HF diets, resulting in a fiber level (FL) × xylanase interaction (P ≤ 0.100). The AID of nitrogen increased with xylanase in LF diets, but decreased in HF diets, resulting in a FL × xylanase interaction (P = 0.025). Xylanase inclusion tended to increase the hindgut disappearance of aNDF and ADF (P ≤ 0.100). In LF diets, xylanase decreased ATTD of ADF, but increased ATTD of ADF in HF diets resulting in a FL × xylanase interaction (P = 0.010). Xylanase inclusion changed the pattern of hindgut disappearance and ATTD of nitrogen over the three collection periods, resulting in a xylanase × collection period interaction. Overall, xylanase supplementation slightly increased digestibility in pigs fed lower fiber diets, and had no impact on digestibility in higher fiber diets.

Estimation of endogenous intestinal losses of acid hydrolyzed ether extract in growing and finishing pigs using the linear regression method.

The approach of this experiment was to apply the regression method for the estimation of endogenous intestinal losses of ether extract (EEE) when pigs are fed complete diets ad libitum and using dietary levels of fat typical of those employed in commercial situations. A total of 40 gilts (PIC 337 sires × C22 or C29) were allotted to individual pens and randomly assigned to diets (8 pigs per treatment) with 5 different levels of acid hydrolyzed ether extract (AEE). The dietary treatments consisted of a corn-soybean meal diet with no added fat (L1); a corn-soy diet with 6% each of corn distiller’s dried grains with solubles (DDGS), corn germ meal, and wheat middlings (L2); the L2 diet but with 12% each of corn DDGS, corn germ meal, and wheat middlings (L3); the L2 diet plus soybean oil to equalize the NE concentration of the L2 diet with L1 (L4); and the L3 diet plus soybean oil to equalize the NE concentration of the L3 diet with L1 (L5). Pigs received feed and water ad libitum for the growing period (initial BW = 38.5 ± 1.2 kg) and the finishing period (initial BW = 73.82 ± 2.9 kg). A quadratic broken-line model was employed to estimate the response of apparent total tract digestibility (ATTD) of AEE to dietary AEE level. The average true total tract digestibility (TTTD) of AEE and endogenous losses of AEE were estimated using regression analysis of dietary AEE intake (g/kg of DM) against apparent digested AEE (g/kg of DMI). The ATTD of AEE increased in curvilinear fashion as dietary AEE level increased in growing and in finishing pigs (P < 0.001). This suggests an influence of EEE on the ATTD of AEE estimates. The linear regression of apparent digested AEE against dietary AEE intake (L1–L5; P < 0.001, R2 = 0.99 for growing pigs and P < 0.001, R2 = 0.99 for finishing pigs) estimated greater EEE (P < 0.05) and TTTD of AEE (P < 0.05) for growing than finishing pigs. Estimated EEE from growing pigs ranged between 18.1 and 20.2 g/kg of DMI, while TTTD of AEE ranged between 96.40% and 100.70%. In finishing pigs, EEE ranged between 21.6 and 23.8 g/kg of DMI and TTTD of AEE ranged between 91.30% and 95.25%. In conclusion, EEE under practical conditions is estimated to be 19.2 g/kg of DMI in growing and 22.7 g/kg of DMI in finishing pigs.

Digestibility of phosphorus in growing pigs as influenced by source and concentration of dietary phosphorus and collection site.

The current study examined the influence of source and concentration of dietary phosphorus (P) on the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of P in growing pigs. Eighteen cannulated barrows (25±5kg) were allotted to a triplicate 6×3 incomplete Latin square design with six diets and three periods. The diets comprised of soybean meal (SBM) or distillers' dried grain with solubles (DDGS) as sole sources of dietary P, and three concentrations of P (2.0, 2.5 or 3.0g/kg) in a 2×3 factorial arrangement. The AID and ATTD of P were not different (p=0.37) in all diets. Apparent digestibility of P was affected (p<0.01) by source and concentration of P. There was no interaction between source and concentration of dietary P on the apparent digestibility of P. Determined by regression analysis, the true ileal digestibility of P was 58.3% or 57.6%, and true total tract digestibility of P was 56.0% or 62.6%, for SBM or DDGS, respectively. The regression-derived ileal endogenous P loss (EPL) was 0.61 or 0.13g/kg DM intake, and total tract EPL was 0.53 or 0.35g/kg DM intake, for SBM or DDGS, respectively. In conclusion, the study demonstrated that both the source and concentration of dietary P affect the digestibility of P in growing pigs.

Copper hydroxychloride improves gain to feed ratio in pigs, but this is not due to improved true total tract digestibility of acid hydrolyzed ether extract

Two experiments were conducted to test the hypothesis that copper (Cu) from Cu hydroxychloride improves gain to feed ratio (G:F) when fed to pigs by increasing apparent total tract digestibility (ATTD) of fat. In experiment 1, 144 pigs (15.40 ± 2.39 kg) were allotted to 6 treatments with 2 pigs per pen and 12 replicate pens per diet. Pigs were fed diets with increasing concentrations of extracted fat by adding 20, 40, or 60 g/kg choice white grease (CWG) to a diet based on corn, soybean meal (SBM), and distillers dried grains with solubles (DDGS), which contained no CWG. Two additional diets were formulated by adding 150 mg/kg of Cu from Cu hydroxychloride to the diet without added CWG and to the diet with 20 g/kg added CWG. Diets were fed for 4 weeks. Results indicated that supplementation of diets with either CWG or Cu hydroxychloride improved (P < 0.05) G:F of pigs, and the improvement obtained by Cu hydroxychloride supplementation was similar to the improvement in G:F obtained by adding 28–38 g/kg CWG to the diets. In experiment 2, 64 pigs (18.22 ± 1.80 kg) were housed individually in metabolism crates and randomly allotted to 8 diets with 8 replicate pigs per diet. Two basal diets based on corn, SBM, corn bran, cornstarch, and casein were formulated. The only difference between the 2 diets was that one diet contained no Cu hydroxychloride, whereas the other diet contained 150 mg/kg of Cu from Cu hydroxychloride. Six additional diets were formulated by adding 150, 300, or 450 g/kg DDGS to both basal diets at the expense of cornstarch and corn bran. Feces were collected using the marker-to-marker approach with 5-day adaptation and 4-day collection periods. Supplementation of Cu hydroxychloride to diets improved (P < 0.05) the ATTD of acid hydrolyzed ether extract (AEE), but did not affect ATTD of dry matter or gross energy (GE). Supplementation of Cu hydroxychloride to diets also reduced (P < 0.05) total tract endogenous loss of fat, but did not affect true total tract digestibility of AEE. This indicates that the increased G:F of pigs that was observed in experiment 1 as a result of Cu supplementation to diets was not due to improved ATTD of GE, but may be a result of Cu influencing post absorptive lipid metabolism. In conclusion, supplementation of Cu from Cu hydroxychloride to diets improved G:F in pigs, which may be due to effects of Cu on post-absorptive metabolism of energy and fat.

Comparison of regression and fat-free diet methods for estimating ileal and total tract endogenous losses and digestibility of fat and fatty acids in growing pigs.

An experiment was conducted to 1) compare the regression and fat-free diet methods for estimating total or basal endogenous losses of fat (ELF) and fatty acids (ELFA) and true digestibility (TD) or standardized digestibility (SD) of fat and fatty acids in growing pigs and 2) compare these estimated values at the end of the ileum and over the entire intestinal tract. Ten barrows (initial body weight: 45.1 ± 2.8 kg) were surgically fitted with a T-cannula in the distal ileum and allotted to one of five experimental diets in a three-period Youden Square design. A fat-free diet was formulated using cornstarch, soy protein isolate, and sucrose. Four oil-added diets were formulated by adding four levels of soybean oil (2%, 4%, 6%, and 8%) to the fat-free basal diet at the expense of cornstarch. All diets contained 26% sugar beet pulp and 0.40% chromic oxide. Results indicated that there were no differences between true ileal digestibility (TID) of fat and true total tract digestibility (TTTD) of fat when pigs were fed soybean oil. The TID of C18:0 and total saturated fatty acids (TSFA) was greater than TTTD (P < 0.05). The total ELF at the end of the ileum were not different from that over the entire intestinal tract. In addition, total endogenous losses of C18:0 and TSFA were greater for the entire intestinal tract than at the end of the ileum, whereas total endogenous losses of C18:2 and total unsaturated fatty acids were just the opposite. Similar results were observed for basal ELF and ELFA. As the inclusion level of soybean oil increased, apparent digestibility (AD) of fat and fatty acids increased linearly (P < 0.05) except for apparent ileal digestibility of C18:0. However, SD of fat and fatty acids was not influenced by the inclusion level of soybean oil. Estimation of ELF and ELFA observed by the regression and fat-free diet methods did not differ when measured at the end of the ileal or total tract. There were no differences between the estimations of TD and SD of fat and fatty acids for soybean oil. Collectively, the estimation of TD or SD of fat can be measured over the entire intestinal tract, whereas the ileal analysis method should be used to determine the ELF, ELFA, and TD or SD of fatty acids. Correcting AD for basal ELF and ELFA can accurately estimate SD values of fat and fatty acids.

Comparative digestibility of polysaccharide-complexed zinc and zinc sulfate in diets for gestating and lactating sows.

We hypothesized that the digestibility of a zinc polysaccharide complex is greater than zinc sulfate when sows consume high fiber diets containing corn dried distillers grains with solubles (DDGS). Gilts and sows (n = 32) were blocked according to parity and assigned randomly to one of four dietary treatments (n = 8 sows per treatments). Dietary treatments consisted of: 1) Control (ConZnSO4)-corn-soybean meal-based diet + 100 ppm supplemental Zn from ZnSO4; 2) Control PSZn (ConPSZn)-corn-soybean meal-based diet + 100 ppm supplemental Zn from Zn polysaccharide complex; 3) DDGS/ZnSO4-corn-soybean meal-40% DDGS gestation diet and a 30% DDGS lactation diet, with each containing 100 ppm supplemental Zn from ZnSO4; 4) DDGS/PSZn-corn-soybean meal-40% DDGS gestation diet and a 30% DDGS lactation diet, with each containing 100 ppm supplemental Zn from Zn polysaccharide complex. A fifth dietary treatment was imposed using a subset of sows (n = 20) to determine basal Zn losses in gestating and lactating sows fed corn-soybean meal-based diets containing no supplemental Zn. Nutrient balance experiments were conducted in both gestation and lactation to evaluate the digestibility of Zn sources of the four dietary treatments and to determine basal Zn losses when no supplemental Zn was provided. The statistical model included fixed effects of diet, Zn source, and their interaction, and random effects of parity. Estimated endogenous losses of Zn were used to adjust apparent total tract digestibility (ATTD) to true total tract digestibility (TTTD) of Zn in the four dietary treatment balance periods. There were no differences in Zn concentrations of urine, plasma, colostrum, or milk samples among treatments at any time of the experiment (P > 0.05). Gestating sows fed DDGS/PSZn had improved (P < 0.05) ATTD, TTTD, and overall retention of Zn compared with both Control treatments, with the DDGS/ZnSO4 treatment responses being intermediate. Lactating sows consuming diets without DDGS and supplemented with Zn polysaccharide complex had the greatest (P < 0.05) ATTD, TTTD, and retention of Zn, which were opposite to responses observed in gestation. Furthermore, ATTD, TTTD, and Zn retention for lactating sows consuming DDGS/PSZn were less (P < 0.05) than all other treatments. Overall, zinc digestibility of ZnSO4 and PSZn appears to be differentially influenced by the stage of the reproductive cycle and presence of dietary fiber from DDGS.

Increasing calcium from deficient to adequate concentration in diets for gestating sows decreases digestibility of phosphorus and reduces serum concentration of a bone resorption biomarker.

The objective of this experiment was to test the hypothesis that the concentration of Ca in diets fed to late gestating sows affects the apparent total tract digestibility (ATTD) and retention of Ca and P, serum concentrations of Ca and P, hormones, and blood biomarkers for bone formation and resorption. Thirty-six sows (average parity = 2.8) were housed in metabolism crates from day 91 to day 104 of gestation and fed 1 of 4 experimental diets containing 25, 50, 75, or 100% of the requirement for Ca. All diets met the requirement for P. The initial 5 d of each period were the adaptation period, which was followed by 4 d of quantitative collection of feces and urine. At the end of the collection period, a blood sample was collected from all sows. Results indicated that feed intake, weights of dried fecal and urine samples, and the ATTD of DM were not affected by dietary Ca, but ATTD of Ca increased (quadratic, P < 0.05) as Ca in diets increased. Urine Ca output was not affected by dietary Ca, but Ca retention increased (quadratic, P < 0.05) as Ca intake increased. Fecal P output increased (linear, P < 0.001) as dietary Ca increased, which resulted in a linear decrease (P < 0.001) in the ATTD of P. Urine P output also decreased (linear, P < 0.001) as dietary Ca increased, but P retention increased (linear, P < 0.05). Regressing the apparent total tract digestible Ca against dietary Ca intake resulted in a regression line with a slope of 0.33, indicating that true total tract digestibility of Ca in calcium carbonate was 33%. Serum concentrations of Ca and P and estrogen, calcitonin, and parathyroid hormone were not affected by dietary Ca. Serum concentration of carboxyterminal cross-linked telopeptide of type I collagen (CTX-I) decreased (linear, P < 0.05) as dietary Ca increased, which is a result of reduced bone resorption as dietary Ca increased. Serum bone-specific alkaline phosphatase tended to decrease (linear, P < 0.10) as Ca in diets increased, but the concentration of osteocalcin (OC) in serum was not affected by dietary Ca. The ratio between OC and CTX-I tended to increase (P < 0.10) as dietary Ca increased, which indicated that there was more bone formation than resorption in sows as dietary Ca increased. In conclusion, P digestibility in late gestating sows decreased, but retention of P increased, as dietary Ca increased from inadequate to adequate levels and blood biomarkers for bone resorption changed as Ca and P retention increased.

Endogenous Losses of Fat and Fatty Acids in Growing Pigs Are Not Affected by Vegetable Oil Sources but by the Method of Estimation.

Simple SummaryApparent digestibility of fat in diets does not reflect the true availability of fat, especially in low-fat diets. Estimation of endogenous losses of fat and fatty acids from the digestive tract is required for the determination of true digestibility of fat. This study evaluates the effect of oil sources on endogenous losses of fat and fatty acids in growing pigs in which endogenous losses were estimated by both regression and fat-free diet methods. Results indicate that the estimated values for endogenous losses of fat and fatty acids were not different in pigs fed palm oil, soybean oil, flaxseed oil or rapeseed oil. The fat-free diet had lower estimated values compared with the regression method. A fat-free diet method deserves to be explored further. These findings contribute to accurate estimation of endogenous losses of fat and fatty acids for vegetable oils in the future.An experiment was conducted to determine the effect of oil sources with differing degrees of fatty acid saturation on endogenous losses of fat (ELF) and fatty acids (ELFA) in growing pigs, in which endogenous losses were estimated by two methods. Sixty-eight growing barrows (initial body weight 31.13 ± 4.44 kg) were randomly allotted to a completely randomized design with 17 diets. Sixteen added-oil diets were formulated by adding four levels (2%, 4%, 6% and 8%) of palm oil (PO), soybean oil (SBO), flaxseed oil (FSO) and rapeseed oil (RSO) to a diet poor in fat, respectively. One fat-free diet was formulated from cornstarch, soy protein isolate and sucrose. All diets contained chromic dioxide (0.4%) as an indigestible marker. Results indicated that, according to the regression equations, the amounts of ELF in PO, SBO, FSO and RSO were 6.28, 5.30, 4.17 and 4.84 g/kg of dry matter intake (DMI), respectively. The true total tract digestibility of fat was greater (p < 0.05) for FSO and RSO than for PO, and the ELFA were different from 0 only for C16:0, C18:0 and C18:1 in FSO, and C16:0 and C18:0 in RSO (p < 0.05). The estimated values for ELF and ELFAs in pigs fed PO, SBO, FSO or RSO were not different. The amount of ELF determined by the fat-free diet method was 2.60 g/kg DMI, and the amounts of C16:0, C18:0, C18:1 and C18:2 in ELFAs were 0.28, 0.26, 0.03 and 0.02 g/kg DMI, respectively. The fat-free diet method had lower ELF and ELFA values compared with the regression method (p < 0.01). Collectively, dietary vegetable oil sources do not affect estimation of ELF and ELFA, but different evaluation methods lead to varying estimates of endogenous losses in pigs.

PSVII-2 Influence of source and concentration of phosphorus on apparent ileal digestibility and apparent total tract digestibility of phosphorus in growing pigs

Abstract A study was conducted to examine the influence of source and concentration of phosphorus (P) on the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of P in growing pigs. Six diets were formulated in a 2 × 3 factorial arrangement with soybean meal (SBM) or corn distillers’ dried grain with solubles (DDGS) as sole sources of dietary P, and concentration of P at 2.0, 2.5 or 3.0 g/kg. Eighteen cannulated pigs (initial BW = 40 ± 5 kg) were allotted to triplicate 6 × 3 incomplete Latin square design with 6 diets and 3 periods, which consisted of 5 d adaption, 2 d fecal collection, and 2 d ileal digesta collection. The results indicated that AID of P was not different from ATTD of P in all diets (P = 0.45). The digestibility of P was affected by source of P (P &amp;lt; 0.01), with mean of 33.7% in SBM and 50.3% in DDGS. The AID of P in SBM increased linearly (P &amp;lt; 0.05) with increasing P concentrations; however, there was no effect of increasing P concentrations on AID and ATTD of P in DDGS. Determined by regression analysis, true ileal digestibility of P was 58.3% or 57.6%, and true total tract digestibility of P was 56.0% or 62.6%, for SBM or DDGS respectively. The estimated ileal endogenous P loss was 0.61 or 0.13 g//kg DMI, and total tract endogenous P loss was 0.53 or 0.35 g/kg DMI, for SBM or DDGS respectively. In summary, source and concentration of dietary P affect the digestibility of P in growing pigs but there was no difference between AID and ATTD of P.

125 Effects of copper hydroxychloride and increasing concentrations of dietary fat on growth performance, total tract endogenous loss of fat, and apparent total tract digestibility of fat by growing pigs

Abstract Two experiments were conducted to test the hypothesis that Cu hydroxychloride (IntelliBond C, Micronutrients, LLC, Indianapolis, IN) improves gain:feed of pigs by increasing apparent total tract digestibility (ATTD) of fat. In experiment 1, 144 pigs (15.40 ± 2.39 kg) were allotted to 1 of 6 treatments. Four diets contained 0, 2, 4, or 6% choice white grease (CWG) and 2 diets contained 150 mg/kg Cu from Cu hydroxychloride and 0 or 2% CWG. Data for growth performance were analyzed by contrast statements, and Cu equivalency of CWG was determined using prediction equations derived from regression procedures using SAS. Results indicated that gain:feed linearly increased (P ≤ 0.05) as CWG concentration increased in diets (Table 1). Supplementation of Cu hydroxychloride to diets improved (P ≤ 0.05) gain:feed of pigs, which resulted in a CWG equivalence of 2.8 to 3.8% for 150 mg/kg Cu hydroxychloride. In experiment 2, 80 pigs (18.24 ± 1.81 kg) were housed individually in metabolism crates and randomly allotted to 1 of 10 diets. Eight diets contained 0, 15, 30, or 45% distillers dried grains with solubles (DDGS) and 0 or 150 mg/kg Cu hydroxychloride. Two additional diets contained 2% CWG and 15% DDGS and 0 or 150 mg/kg Cu hydroxychloride. Feces were collected for 4 d after 5 d adaptation. Data were analyzed by contrast statements and regression procedures using SAS. Supplementation of Cu to diets improved (P ≤ 0.05) ATTD of fat by 20% due to reduced (P ≤ 0.05) endogenous loss of fat (from 11.23 to 7.14 g/kg dry matter intake), but did not affect energy digestibility or true total tract digestibility of fat. In conclusion, supplementation of 150 mg/kg Cu hydroxychloride to diets improved gain:feed of pigs with a CWG equivalence of 2.8 to 3.8%, but this was not due to improved energy digestibility.

Effects of dietary fiber content and different fiber-rich ingredients on endogenous loss of fat and fatty acids in growing pigs

Effects of dietary fiber content and different fiber-rich ingredients on endogenous loss of fat and fatty acids in growing pigs

Determination of endogenous fat loss and true total tract digestibility of fat in mink (Neovison vison)

ABSTRACTThe objective of this study was to determine the endogenous fat loss (EFL) and to calculate true total tract digestibility (TTTD) of fat in mink (Neovison vison) using soybean oil–based diets with different fat levels. In the digestibility assay, four diets with 6.30%, 13.9%, 22.0% and 34.0% fat in dry matter were used. Sixteen adult male mink were distributed in a complete randomised design. The apparent total tract digestibility (ATTD) of dietary fat was 90.8%, 95.9%, 96.9% and 97.8%, respectively. The apparent total digestible fat was linearly related to dietary fat intake (r2 = 0.99). The EFL was estimated from the slope of the regression equation and was determined to be 5.09 g/kg DM intake. The TTTD of soybean oil was determined to be 99.3%. Therefore, TTTD values will have negligible impact in feed formulation as they are close to ATTD values with the dietary fat levels normally used for mink.

Estimation of apparent and true total tract digestibility of phosphorus from monocalcium phosphate in broiler diets

Summary The aim of this trial was to determine the apparent and true total tract digestibility of phosphorus from monocalcium phosphate, as an inorganic P source in a broiler diet. The trial included 300 one-day-old broiler chickens (Cobb 500), which were randomly divided into three groups – by one hundred birds each. The experiment lasted 42 days, and was divided into three periods (days 1–21 for starter, days 21–35 for grower, and days 35–42 for finisher). One group of broilers was fed a diet without the addition of MCP (basal diet), and the other two experimental groups received different monocalcium phosphates. Cr 2O 3 was added to the diets at a 0.5% level as an indigestible marker. The production results (average body weight, average daily gain, feed intake and feed to gain ratio) were monitored during the trial. At day 11 and day 25, 10 birds from each group were placed into individual balance cages, in order to provide the collection of faeces during 5 consecutive days. The apparent and true total tract digestibility of P, as well as the apparent total tract digestibility of Ca were determined. Results showed that apparent total tract digestibility of P was influenced by the source of inorganic P ( P<0.001). It was concluded that the utilisation of P was not significantly affected by the age of broilers, and the level of digested Ca did not represent the limiting factor for P digestibility in this experiment.

True is more additive than apparent total tract digestibility of calcium in limestone and dicalcium phosphate for twenty-kilogram pigs fed semipurified diets.

Two experiments were conducted to determine the Ca digestibility of limestone and dicalcium phosphate (DCP) and if values for Ca digestibility are additive in mixed diets for pigs. In Exp. 1, 48 barrows with an average initial BW of 19.2 ± 1.1 kg were assigned to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement of 2 Ca sources, including limestone or DCP, and 3 dietary Ca concentrations of 0.54, 0.74, or 0.94%. Diets were fed for a 5-d adjustment period followed by a total collection period of 5 d with chromic oxide and ferric oxide as markers to determine the initiation and termination of fecal collection, respectively. Results indicated that the increased dietary Ca concentration linearly increased ( < 0.01) Ca intake, digested Ca, and retained Ca but did not affect the apparent total tract digestibility (ATTD) of Ca or Ca retention of intake (%). The ATTD of P and P retention of intake were linearly increased ( < 0.05) as dietary Ca and P increased. In Exp. 2, 72 barrows with an average initial BW of 20.8 ± 1.3 kg were assigned to 1 of 9 dietary treatments in a 3 × 3 factorial arrangement of 3 Ca sources, including limestone, DCP, or the mixture of the 2 at a ratio of 1:1, and dietary Ca concentrations of 0.40, 0.50, or 0.60%. Feeding and sample collection procedures were as in Exp. 1. The results also showed that increased Ca concentration linearly increased ( < 0.001) Ca intake, fecal Ca output, and Ca absorbed but did not affect the ATTD of Ca within each Ca source. The average ATTD were 66.46, 70.34, and 69.32% for the limestone, DCP, and mixed diets, respectively. By regressing daily digested Ca against daily Ca intake, the true total tract digestibility (TTTD) of Ca was determined to be 70.06, 76.42, and 73.72% for the limestone, DCP, and mixed diets, respectively. The predicted TTTD for Ca in the mixed diets of limestone and DCP was calculated to be 72.67% based on the Ca contribution coefficient of 0.59 for limestone and 0.41 for DCP. The predicted Ca TTTD (72.67%) in the mixed diets was not different from the Ca TTTD (73.72%) determined using the regression method. It is concluded that although the ATTD of limestone and DCP were not affected by the Ca concentration in the diet, TTTD is recommended for evaluation of Ca digestibility because of its additivity in a mixed diet.

Nutritive Value of Sorghum Dried Distillers Grains with Solubles and its Effect on Performance in Geese.

The study was conducted to determine the chemical composition and nutritive value of sorghum dried distillers grains with solubles (sDDGS) and its effect as a feed supplement on the performance of geese. Experiment 1 showed that the gross energy, crude protein, ether extract, crude fiber, calcium, phosphorus, and amino acid content values of sDDGS were 17.87 MJ/kg and 15.48, 4.26, 31.46, 0.17, 0.25, and 0.06–3.18% [dry matter basis (DM)], respectively. Experiment 2 used fasting–force feeding to measure the true metabolizable energy of sDDGS (11.38 MJ/kg DM) and true total tract digestibility of amino acids (43.16–80.92% DM) in geese. Experiment 3 examined the effectiveness of sDDGS as a feed supplement for geese. Three hundred and fifteen 35-day-old male Sichuan white geese with an initial average bodyweight of 1,732 g were randomly allocated to five treatments. Geese in each treatment group were fed one of five experimental diets (control diet alone, or supplemented with 4, 8, 12, or 16% sDDGS) until 70 days of age. Inclusion of sDDGS in the diet did not affect daily average weight gain (P>0.05). Birds fed diets containing up to 8% sDDGS had higher average feed intake (P<0.05) than geese fed the control diet, and the feed/gain ratio in geese fed diets containing 16% sDDGS was higher (P<0.05) than in the control and the 4% sDDGS group. The yields of breast meat, leg meat, subcutaneous fat and skin, and abdominal fat were not affected (P>0.05) bydietary sDDGS levels. Generally, sDDGS is a potentially valuable feedstuff for geese, but it should be supplemented with a high-energy or protein-rich ingredient. To improve growth performance and carcass yield, up to 12% sDDGS can be included in diets from 35 to 70 days of age.

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

Fat plays an important role in the carnivore diet. It has high digestibility and high energy content and likely improves digestibility of the diet when present in greater amounts, suggesting that endogenous fat adversely affects the apparent digestibility of fat in low-fat diets. This study aimed to determine the endogenous fat loss (EFL) and true total tract digestibility (TTTD) of fat in dogs by using diets having different fat:carbohydrate ratios. Furthermore, the apparent total tract digestibility (ATTD) of macronutrients and energy, food intake, fecal output, and stool quality were evaluated. Twelve adult Beagle dogs were stratified into three 10-d periods in a 6 × 3 balanced incomplete Latin square design. Dietary treatments included a low-fat basal diet (3.4% fat) supplemented with 6 poultry fat levels (1, 4, 10, 12, 16, or 20%). The dogs were individually housed in metabolic cages and fed to meet the maintenance energy requirements. The ME intake was similar across the diets, despite the clearly low palatability of the 1 and 4% fat diets. Dietary ATTD of DM, OM, fat, and GE were improved after fat inclusion ( < 0.001). The ATTD of CP was not affected by dietary fat increase ( > 0.05). The amount of fecal output decreased with increasing level of fat in the diet, but the fecal score was not affected. The stool quality was close to ideal (2.4-2.8) and no different among diets. The EFL was estimated using 2 regression methods and was expressed as 155 mg∙kg BW∙d or 7.9 g/kg of DMI. The TTTD of poultry fat was the same irrespective of the dietary fat level. Poultry fat was 99.3% digestible for the dogs. The relation between EFL and fat intake was higher for the lower-fat diets, explaining the ATTD of fat increase according to the dietary fat inclusion. In conclusion, dietary fat is well digested by dogs irrespective of the level included, close to 100%. The ATTD of fat in low-fat diets is underestimated because the endogenous content is proportionally greater than that in high-fat diets.