Effects of collection time on flow of chromium and dry matter and on basal ileal endogenous losses of amino acids in growing pigs

Effect of extrusion on available energy and amino acid digestibility of barley, wheat, sorghum, and broken rice in growing pigs

OBJECTIVE

The main objective of this study was to determine available energy and nutritional digestibility of extruded cereals and the effect of extrusion on the nutritional value of feed ingredients, aiming to provide scientific basis for efficient application of extrusion in the diets of growing pigs.

METHODS

In Exp. 1, 48 crossbred growing pigs (Duroc×Landrace×Yorkshire) with an initial body weight (BW) of 34.6±2.2 kg were selected and fed with eight diets (non-extrusion or extrusion) to determine the digestible energy (DE), metabolizable energy (ME), and nutrients digestibility. Eight diets included extruded grains (barley, wheat, sorghum, or broken rice), while four had unprocessed grains. In Exp. 2, 9 diets were formulated including 4 cereals with extrusion or non-extrusion and a N-free diet. In addition, 9 growing pigs (BW = 22.3±2.8 kg) were fitted with T-cannula in the distal ileum and arranged in a 9×6 Youden square design.

RESULTS

Results show that apparent total tract digestibility of gross energy, dry matter, organic meal, ether extract, neutral and acid detergent fiber was not affected by the extrusion process and there was no interaction between cereal type and extrusion treatment on DE, ME. However, the apparent total tract digestibility for crude protein (CP) increased markedly (p<0.05). The standardized ileal digestibility (SID) of all amino acids (AA) except for leucine remarkably increased by extrusion (p<0.05). There was an interaction on the SID of arginine, leucine, isoleucine, methionine, phenylalanine, cystine, and tyrosine in growing pigs between type of grain and extrusion treatment (p<0.05).

CONCLUSION

Extrusion increased the ileal digestibility of CP and most AA in cereals, however, the DE and ME of cereals were not affected in growing pigs.

Determination of ileal endogenous nitrogen losses and true ileal nitrogen digestibility during non-steady-state conditions of the 15N-isotope dilution technique

The aim was to determine ileal endogenous nitrogen losses (ENL) and true ileal N-digestibility (TD-N) under non-steady-state conditions of the 15N-isotope dilution technique (15N-IDT), using diets generating low and high ENL and compare results to those obtained under steady-state conditions. Twelve growing pigs (mean LW 22.4 kg) fitted with a post-valve T-caecum cannula were fed an enzyme-hydrolysed casein (EHC)-based diet or an EHC diet + 4% quebracho tannins (QT) and were labelled via continuous 15N-leucine i.v. infusion or twice daily oral 15N-leucine administration. Digesta were collected daily over three consecutive hours with blood plasma sampled on the four consecutive days after cessation of 15N-labelling. There was a significant effect of sampling day on the dilution factor. Endogenous N losses were significantly lower for the EHC than the EHC+QT diet (2.41 vs. 8.69 g/kg DMI), while no significant effect of sampling day was observed. The TD-N of the EHC+QT diet did not differ from the TD-N of the EHC diet (95.1 vs. 92.0%). A significant effect of sampling day was observed for TD-N with day 1 and 2, being higher than day 4. Non-steady-state conditions overestimated ENL by 25-28% as compared to 3 h collections in steady-state conditions, but the relative overestimation was similar for the EHC diet as for the EHC+QT diet. TD-N did not differ significantly compared to 12 h steady-state measurements, but comparison to 3 h steady-state measurements showed that non-steady-state conditions overestimated TD-N for the EHC+QT diet by 9%. However, on day 4 this overestimation disappeared. Using the 15N-IDT during non-steady-state conditions can provide valuable additional data on endogenous N losses and TD-N.

Pea starch increases the dry matter flow at the distal ileum and reduces the amino acids digestibility in ileal digesta collected after 4 hours postprandial of pigs fed low-protein diets

Objective

The study was aimed to investigate the rules of postprandial changes in intestine digesta dry matter (DM) flow and amino acid digestibility of growing pigs fed low-protein (LP) diets made of different starch.

Methods

Eight barrows (28.8±2.1 kg) with a T-cannula at the distal ileum were randomly allotted to an 8×3 Youden square design. Treatments included: waxy corn starch LP (WLP); corn starch LP (CLP) and pea starch LP (PLP). Diets were given at 08:00 and 20:00. Digesta samples were collected in six 2-h stages from 08:00 to 20:00.

Results

The Cr concentrations of ileal digesta increased and then decreased in WLP and CLP, while increased continuously in PLP as time passed after postprandial (p<0.05). Higher average Cr concentrations (0.78% and 0.84% vs 0.70%; p<0.05) and lower average DM flow (181.1 g/kg and 166.3 g/kg vs 240.3 g/kg; p<0.001) were observed in WLP and CLP, compared with PLP. The apparent ileal digestibility coefficient of most amino acids in WLP and CLP increased compared with that in PLP. No difference in lysine or methionine digestibility was observed. When digesta were collected in 2-h periods, the apparent ileal digestibility coefficient of amino acids did not change over time. When digesta was collected in 4-h periods from 16:00 to 20:00 and 6-h periods from 14:00 to 20:00 (p<0.05), WLP and CLP showed markedly higher amino acid digestibility than PLP

Conclusion

High-amylose slowly digested starch can increase the DM flow at the distal ileum and reduce the apparent ileal digestibility coefficient of amino acids of pigs fed LP diets. Compared with waxy corn starch and corn starch, pea starch reduced the digestibility of amino acids in digesta collected after 4 h postprandial.

Effects of different defatted rice bran sources and processing technologies on nutrient digestibility in cannulated growing pigs

The objective of this study was to evaluate the effects of different defatted rice bran (DFRB) sources and processing technologies on nutrient digestibility in different intestinal segments of pigs. Nine barrows with T-cannula in the distal ileum were randomly allotted to nine different sources in which oil was pressed extracted for seven sources and was solvent extracted for two sources. The experiment contained 6 periods of 12 d, including 8 d for diet adaptation, 2 d for fecal collection, and 2 d for digesta collection. The apparent ileal digestibility (AID) of dry matter (DM), ash, total dietary fiber (TDF), insoluble dietary fiber (IDF), neutral detergent fiber (NDF), acid detergent fiber (ADF), and hemicellulose in different sources of DFRB was quite variable. There were no differences in the AID of dietary gross energy (GE), organic matter (OM), ether extract (EE), crude protein (CP), and soluble dietary fiber (SDF) between different sources of DFRB. There were no differences in the AID of dietary EE, TDF, IDF, and hemicellulose between different processing technologies. Pressed DFRBs have greater (P < 0.05) average AID of dietary GE, DM, ash, OM, CP, SDF, and NDF and lower (P < 0.01) ADF compared with solvent-extracted DFRBs. The apparent total tract digestibility (ATTD) of most of the dietary nutrients, except for the ATTD of dietary EE, SDF, and hemicellulose, significantly varied in different sources of DFRB (P < 0.05). In addition, pressed DFRB had greater (P < 0.05) ATTD of dietary SDF, NDF, ADF, and hemicellulose compared with solvent-extracted DFRB. The apparent hindgut digestibility (AHD) of dietary DM, SDF, NDF, and ADF significantly varied (P <0.05) in different sources of DFRB. Exception with DM, there are no differences in the AHD of nutrients digestibility between pressed DFRB and solvent-extracted DFRB. In conclusion, DFRB in different sources and processing technologies with different physicochemical properties had different effects on nutrient digestibility in the foregut and hindgut of pigs.

Technical note: Establishment of an ileal cannulation technique in preweaning calves and use of a piecewise regression approach to evaluate effects on growth and pH fluctuation of ileal digesta

Digestibilities of nutrients, especially protein, are crucial characteristics of milk replacers in a calf-rearing program. Endogenous synthesis of proteins and microbial fermentation in the large intestine alter apparent total-tract digestibility of AA. Therefore, collection of digesta samples at the end of the ileum is the only method to estimate true small intestinal digestibility of AA. The aim of this work was to evaluate the effectiveness of inserting a T-cannula into the distal ileum of preweaning calves for use in digestibility studies. A second objective was to evaluate the use of a "broken-line" statistical model to compare treatment effects on calf growth and digesta pH. A T-cannula was surgically installed in the terminal ileum of 2 calves approximately 5 cm anterior to the ileocecal junction at 15 d of age, and 2 paired noncannulated calves were used as controls. Cannulation did not affect mean body weight (BW), average daily gain, milk and water intakes, and body frame dimensions. However, final BW (89.2 vs. 94.6 kg) was lower and starter intake (0.06 vs. 0.21 kg/d) tended to be decreased in cannulated calves compared with control calves. No effects on health scores, rectal temperature, or the odds of incurring diarrhea or being medicated were observed. Flow of digesta (46.4 ± 0.04 g/h) increased linearly after feeding, whereas there was a quadratic effect of time on digesta pH, with the nadir at approximately 8.5 h postfeeding. The broken-line model successfully fitted daily fluctuations of pH and allowed us to detect differences in growth slopes between cannulated and control calves. Despite the expected negative effect on BW, we conclude that this technique permitted sampling of representative ileal digesta while allowing satisfactory growth and health of the calves.

Available energy and amino acid digestibility of defatted rice bran fed to growing pigs

This study was conducted to determine and compare available energy and apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP and AA in 9 samples of defatted rice bran (DFRB) fed to growing pigs and to generate prediction equations for DE and ME based on chemical analysis. In Exp. 1, 60 crossbred growing pigs (Duroc × Landrace × Yorkshire; 40.7 ± 3.5 kg BW) were fed 1 of 10 diets in a completely randomized design to determine the available energy of DFRB. The diets included a corn-soybean meal-basal diet and 9 experimental diets formulated by replacing the corn and soybean meal with 29.16% DFRB. In Exp. 2, 6 growing pigs (initial BW = 28.5 ± 2.8 kg) were surgically equipped with a T-cannula in the distal ileum and arranged in a 6 × 6 Latin square design with 6 diets and 6 periods. The diets included an N-free diet based on cornstarch and sucrose and 5 experimental diets containing 60% DFRB as the sole source of AA. Chromic oxide (0.3%) was used as an indigestible marker. Among the 9 samples, the concentrations of ether extract (EE), crude fiber (CF), NDF, ADF, starch, Ca, and P averaged 1.33 (0.50% to 4.14%), 14.54 (9.78% to 23.85%), 28.62 (20.19% to 38.85%), 14.22 (9.32% to 23.99%), 38.80% (30.62% to 47.55%), 0.16% (0.09% to 0.24%), and 1.96% (1.11% to 2.28%), respectively. The average DE and ME were 2,643 and 2,476 kcal/kg DM, respectively, and ranged from 2,039 to 3,157 kcal/kg DM and 1,931 to 2,978 kcal/kg DM, respectively. In Exp. 2, there were significant differences in the AID and SID of CP and most AA except for His, Tyr, and Met (P < 0.05). The AID and SID of CP averaged 67.75% and 76.37%, respectively. The digestibility of Met was the greatest, averaging 86.15% and 90.08% for AID and SID, respectively. The AID and SID of Lys ranged from 51.88% to 71.43% (mean = 63.27%) and from 61.93% to 79.98% (mean = 72.97%), respectively. These results indicated that there is significant variability in chemical composition, energy content, and the SID and AID of CP and most AA among the selected DFRB. The DE and ME of DFRB are primarily related to their NDF and starch concentrations.

Techniques for evaluating digestibility of energy, amino acids, phosphorus, and calcium in feed ingredients for pigs

Sound feed formulation is dependent upon precise evaluation of energy and nutrients values in feed ingredients. Hence the methodology to determine the digestibility of energy and nutrients in feedstuffs should be chosen carefully before conducting experiments. The direct and difference procedures are widely used to determine the digestibility of energy and nutrients in feedstuffs. The direct procedure is normally considered when the test feedstuff can be formulated as the sole source of the component of interest in the test diet. However, in some cases where test ingredients can only be formulated to replace a portion of the basal diet to provide the component of interest, the difference procedure can be applied to get equally robust values. Based on components of interest, ileal digesta or feces can be collected, and different sample collection processes can be used. For example, for amino acids (AA), to avoid the interference of fermentation in the hind gut, ileal digesta samples are collected to determine the ileal digestibility and simple T-cannula and index method are commonly used techniques for AA digestibility analysis. For energy, phosphorus, and calcium, normally fecal samples will be collected to determine the total tract digestibility, and therefore the total collection method is recommended to obtain more accurate estimates. Concerns with the use of apparent digestibility values include different estimated values from different inclusion level and non-additivity in mixtures of feed ingredients. These concerns can be overcome by using standardized digestibility, or true digestibility, by correcting endogenous losses of components from apparent digestibility values. In this review, methodologies used to determine energy and nutrients digestibility in pigs are discussed. It is suggested that the methodology should be carefully selected based on the component of interest, feed ingredients, and available experimental facilities.

Effects of ileal digesta collection time on standardized ileal digestibility of amino acids in corn, soybean meal, and distiller's dried grains with solubles fed to growing pigs

The objective of this experiment was to determine the minimum collection time needed to obtain representative samples of ileal digesta from pigs fed different types of diets. Eight barrows with an initial BW of 34.6 kg (SD 2.1) were individually fitted with a T-cannula in the distal ileum and randomly allotted to a replicated 4 × 4 Latin square design with 4 diets and 4 periods per square. Three diets contained corn, soybean meal (SBM), or distiller's dried grains with solubles (DDGS) as the sole source of CP. An N-free diet was also prepared. All diets contained 0.5% chromic oxide as an indigestible marker. Equal meals were provided at 0800 and 2000 h. Ileal digesta samples were collected in 2-h intervals from 0800 to 2000 h during the last 3 d of each 7-d period. When pigs were fed the corn diet, the standardized ileal digestibility (SID) of most indispensable AA and dispensable AA increased and then decreased (quadratic, < 0.05) during each of the six 2-h periods. The SID of most AA were less ( < 0.05) if the ileal digesta samples were collected from 1800 to 2000 h or from 1600 to 2000 h compared with the SID values from the ileal samples collected over the entire 12-h period. When pigs were fed the SBM diet, the SID of Ile, Leu, Thr, Trp, Val, Ala, and Cys increased and then decreased (quadratic, < 0.05) but the SID of all other AA linearly decreased ( < 0.05) during the six 2-h periods. The SID of almost all AA were greater ( < 0.05) if the ileal samples were collected from 0800 to 1000 h, from 0800 to 1200 h, from 1000 to 1400 h, or from 0800 to 1400 h but less ( < 0.05) if collected from 1600 to 1800 h, from 1800 to 2000 h, from 1600 to 2000 h, or from 1400 to 2000 h compared with the SID values from the ileal samples collected over the entire 12-h period. When pigs were fed the DDGS-based diet, the SID of Ile, Leu, Lys, Phe, Trp, Val, and Tyr increased and then decreased (quadratic, < 0.05) during the six 2-h periods. The SID of most AA were less ( < 0.05) if the ileal samples were collected from 1800 to 2000 h compared with the SID values from the ileal samples collected over the entire 12-h period. In conclusion, diurnal variations in SID of AA in pigs indicate that 6 h of ileal sample collection starting 4 or 6 h after feeding may provide representative samples of ileal digesta from pigs fed different types of diets.