Effects of lipid form and source on digestibility of fat and fatty acids in growing pigs

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.

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.

Effect of a Multi-Carbohydrase and Phytase Complex on the Ileal and Total Tract Digestibility of Nutrients in Cannulated Growing Pigs

The current study evaluated the influence of a multi-carbohydrase and phytase complex (MCPC) on the ileal and total tract digestibility of nutrients in growing pigs. A total of eight barrows (initial BW = 30.7 ± 1.1 kg) were surgically fitted with a T-cannula at the distal ileum and randomly allotted to four groups. The experiment was conducted according to a 4 × 4 Latin square design, each period lasting 10 days. Pigs were fed four experimental diets, which consisted of two basal diets (BD1, low phytate; BD2, high phytate) with or without MCPC containing at least 1800 U xylanase, 6600 U α-arabinofuranosidase, 1244 U β-glucanase, and 1000 U phytase per/kg corn-soybean meal with 15% corn distillers based diet. The high phytate diet reduced (p < 0.05) the apparent ileal digestibility (AID) of crude protein by 1.4% and the apparent total tract digestibility (ATTD) of organic matter, crude protein, and gross energy by 1.7, 2.3, and 1.9%, respectively, and tended to decrease (p = 0.10) the ATTD of Ca by 17.3%, relative to the low phytate diet. The dietary supplementation of the MCPC increased (p < 0.05) the AID of phosphorus (P) and calcium (Ca) by 34.2% and 31.1% for BD1 and 26.7% and 41.3% for BD2, respectively, and increased (p < 0.05) ATTD of crude fat, P, and Ca by 1.4%, 45.6%, and 9.6% for BD1 and 3.1%, 66.0%, and 52.7% for BD2, respectively. The MCPC supplementation did not significantly increase the AID and (or) ATTD of crude protein, organic matter, and starch. In conclusion, the dietary supplementation of the MCPC could improve the AID of P and Ca and the ATTD of crude fat, P, and Ca.

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

Simple Summary

Apparent 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.

Abstract

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.

Effects of particle size and lipid form of corn on energy and nutrient digestibility in diets for growing pigs

Objective

Two experiments were conducted to evaluate the effects of corn particle size and lipid form on the apparent total tract digestibility (ATTD) of energy and nutrients in diets for growing pigs.

Methods

In Exp. 1, thirty barrows (initial body weight [BW], 53.1±3.9 kg) were allotted to 1 of 5 diets formulated with 96.9% corn ground to 441, 543, 618, 659, and 768 μm, respectively. In Exp. 2, thirty-six barrows (initial BW, 54.7±3.6 kg) were allotted to 1 of 6 diets formulated by including 2% or 15% corn germ (CG 2 or CG 15), 1% or 6% corn oil (CO 1 or CO 6), 1% CO+2% corn germ meal (CO 1+CGM 2), or 6% CO+15% corn germ meal (CO 6+CGM 15), respectively.

Results

The ATTD of gross energy (GE) and the digestible energy (DE) in diet and corn grain linearly decreased as the corn particle size increased (p<0.05) from 441 to 768 μm. Particle size had a quadratic effect (p<0.05) on the ATTD of neutral detergent fiber and acid detergent fiber in diets, and which firstly increased and then decreased as the corn particle size increased from 441 to 618 μm and 618 to 768 μm, respectively. The ATTD of GE, ether extract (EE), and the DE in CO 1 diet and CO 6 diet was greater (p<0.05) than that in CG 2 diet and CG 15 diet, respectively. The ATTD of EE in CO 6 diet and CO 6+CGM 15 diet was greater (p<0.05) than that in CO 1 diet and CO 1+CGM 2 diet.

Conclusion

Less than 618 μm was recommended for corn particle size in growing pig’s diet and extracted lipid had greater digestibility than the intact lipid in corn. Higher concentration of extracted CO had greater digestibility of EE compared with lower concentrations of CO diet.

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

Background

Determination of the endogenous loss of fat (ELF) is used to adjust for the estimation of true total tract digestibility (TTTD) of fat in diets and ingredients. Any factor which affected ELF may further affect the digestibility of fat, including sources and concentrations of fat and fiber in the diet. There are some reports of determining the ELF using regression methods based on different levels of fat intake, while reports on effects of dietary fiber content and different fiber-rich ingredients in pig diets on ELF are very limited. Therefore, the objective of this study was to determine the effects of dietary fiber content and different fiber-rich ingredients on endogenous losses of fat and fatty acids at the end of ileum and throughout the entire intestinal tract in growing pigs.

Methods

In Exp. 1, the effect of fiber content on endogenous loss of fat was determined using six growing pigs (Duroc × Landrace × Yorkshire; 27.6 ± 2.4 kg), fitted with a T-cannula at the end of ileum. The experimental design was a 6 × 6 complete Latin square design with six periods of feeding and six diets. The six experimental fat-free diets were formulated to include graded levels of neutral detergent fiber (NDF) (0, 40, 80, 120, 160 and 200 g/kg) and soybean hull (SH) was the only fiber source, providing 0, 75, 150, 225, 300 and 375 g/kg, respectively. Chromic oxide was included at 4 g/kg in all diets as an indigestible marker. In Exp. 2, six crossbred growing barrows (27.6 ± 1.6 kg) were used and the experimental design was the same as for Exp. 1. The six fat-free diets were formulated to include six common fiber-rich ingredients and the concentration of NDF was 100 g/kg. The six fiber-rich ingredients were defatted rice bran (DRB), sugar beet pulp (SBP), rice hull (RH), corn germ meal (CGM), SH and wheat bran (WB) and they were fed at represented 250, 270, 145, 250, 170 and 280 g/kg in the diet, respectively.

Results

In Exp. 1, the endogenous loss of fatty acids profile did not change as dietary NDF increased in growing pigs. The endogenous losses of fat, C16:0, C18:0, C18:1, C18:2, total unsaturated fatty acids (UFA) and total saturated fatty acids (SFA) in growing pigs at the end of ileum and throughout the entire intestinal tract increased linearly as NDF content of diets increased. The endogenous losses of fat, as well as C16:0 and C18:0 throughout the entire intestinal tract also increased quadratically as NDF content of diets increased. The ELF increased from 0.71 to 3.14 g/kg of dry matter intake (DMI) and 0.56 to 8.21 g /kg DMI at the end of ileum and throughout the entire intestinal tract in growing pigs, respectively. The ELF occurred in the hindgut except for the growing pigs fed 0 and 4% NDF in their diets. The endogenous losses of C16:0 and UFA occurred primarily in the upper regions of the gut and the greatest endogenous losses of C18:0 occurred in the hindgut. The endogenous losses of fat, individual SFA and total SFA throughout the entire intestinal tract were much greater than that at the end of ileum. However, the endogenous losses of individual UFA and total UFA were less throughout the intestinal tract than at the end of ileum. In Exp. 2, the endogenous losses of fat at the end of ileum were greater in growing pigs fed CGM or WB diets. The endogenous loss of fatty acids profile changed to a slight degree at the end of ileum that the endogenous loss of UFA (particularly C18:1 and C18:2) in growing pigs fed CGM or WB diets were greater (P <  0.01) than that for the other four diets. The greatest (P <  0.01) endogenous loss of SFA (particularly C18:0) was in growing pigs fed the RH diet. The endogenous losses of fat, C16:0, C18:0 and SFA over the entire intestinal tract were much greater in growing pigs fed CGM or WB diets, whereas the lowest values were in growing pigs fed DRB diet. The ELF at the end of ileum in growing pigs fed CGM or WB diets were 3.50 or 4.17 g/kg DMI, respectively, and the ELF over the entire intestinal tract was 7.23 or 7.38 g/kg DMI. The contribution in percentage of ELF in the upper gut was greater than that in the hindgut of growing pigs fed DRB and RH diets, while the ELF in the upper gut and hindgut were equal in growing pigs fed SBP, CGM and WB diets. On the whole, the endogenous losses of C18:1 and C18:2 throughout the entire intestinal tract in growing pigs fed the six fiber-rich ingredients diets were less than losses at the end of ileum, whereas the endogenous loss of fat, C16:0, C18:0 and SFA were greater throughout the intestinal tract than at the end of ileum.

Conclusion

The profile of loss in endogenous fatty acids did not change as dietary NDF increased in growing pigs and the endogenous losses of fatty acids (C16:0, C18:0, C18:1 and C18:2) fat, UFA and SFA increased linearly as NDF content increased in the diets of pigs. The endogenous losses of fat or fatty acids at the end of ileum were greater in growing pigs fed RH, CGM or WB diets. The endogenous losses of fat, fatty acids (C16:0 and C18:0) and SFA were greater over the entire intestinal tract in pigs fed CGM or WB diet, while these values were the lowest in growing pigs fed the DRB diet. The contribution in percentage losses of fat in the upper gut were greater than in the hindgut of growing pigs fed DRB and RH diets, while the contribution of losses of fat in the upper gut and hindgut were equal in growing pigs fed SBP, CGM and WB diets. In addition, the endogenous loss of individual or total UFA was less over the entire intestinal tract of growing pigs fed fiber diets than that at the end of ileum, and the greatest endogenous losses of fat, individual or total SFA were over the entire intestinal tract. Therefore, differences in fiber content and the nature of fiber-rich ingredients in diets of pigs have different effects to the endogenous losses of fat or fatty acids. Considering the requirement of fat or fatty acids of pigs, careful attention must be paid that the endogenous losses of fat and fatty acids when fiber ingredients are used in diets of pigs.