Precaecal Digestibility Research Articles

Effects of herbage ingestion on the digestion site and nitrogen balance in heavy Iberian pigs fed on an acorn-based diet

We conducted two experiments in heavy-weight Iberian pigs to determine: a) the effect of lysine or protein addition – the former as l-lysine·HCl, the latter by fresh cut herbage supplementation – on protein deposition when they were fed on holm-oak acorns; b) the digestibility of energy and nutrients in acorns and freshly cut, mixed herbage; and c) a possible change in the partition of digestion along the gastro-intestinal tract of the pigs fed on acorns with the inclusion of herbage. In Experiment 1, carried out in eight cannulated pigs, the daily intake of acorns reached 44.9 g DM/kg 0.75 BW and the addition of 0.58 g l-lysine/kg of whole acorns failed to alter N retention significantly ( P > 0.05). We obtained high coefficients for the apparent total-tract digestibility of dry matter (ApDM tt, 0.84) and organic matter (ApOM tt, 0.86) and of gross energy (ApGE tt, 0.84) in whole acorns. The corresponding ileal values were 0.71, 0.74 and 0.74. The N balance was on average − 1.08 g/day. In Experiment 2, fresh herbage containing principally legumes was offered to six cannulated Iberian pigs of 140 kg either as a single feed (13.7 g DM/kg 0.75 BW) or as a supplement to acorns (28.4 g DM/kg 0.75 BW; in this case the herbage accounted for 22% of the daily DM intake). The apparent ileal digestibilities of OM and GE for herbage accounted for 70 to 77% of the values observed at total-tract level (0.65 and 0.64 respectively). N retention reached 4.21 g/day. Average ApDM tt, ApOM tt and ApGE tt in the herbage/whole-acorn mixture were slightly above 0.74. The intake of freshly cut herbage as complementary feed to acorns resulted in a significant transference of digesta from the small intestine to the hind gut together with a substantial decrease in ileal digestibility of nutrients and energy ( P < 0.001) and a moderate decline in digestibility at throughout the whole tract ( P < 0.01– P < 0.001). On the other hand, the apparent digestibility of total N increased ( P < 0.001) and 31% of the N apparently digested was retained in the body of the pigs. We also observed a substantial decrease in the precaecal digestion of the DM ( P < 0.01), OM ( P < 0.01) and GE ( P < 0.05) in acorn kernels. We concluded that the main contribution of herbage to the overall nutrient supply to the grazing Iberian pig would rely upon the provision of amino acid N and also of available minerals, both present in low quantities in acorns.

Comparison of a xylanase and a complex of non starch polysaccharide-degrading enzymes with regard to performance and bacterial metabolism in weaned piglets

Weaned piglets were fed a wheat based diet either non-supplemented or supplemented with a multi-enzyme preparation or a xylanase mono-enzyme preparation, respectively. Both enzyme preparations increased live weight gain nonsignificantly, but only animals of the xylanase group showed a trend (p = 0.076) for an improved feed conversion. Only precaecal digestibility of total amino acids was improved significantly when the mono-enzyme preparation was added. Improvements of digestibility of crude fat, crude protein and starch did not reach the significance level. Both enzyme preparations reduced jejunal viscosity, however viscosity in the colon was only reduced by the mono-enzyme preparation. Both enzymes significantly reduced Lactobacillus spp. cell numbers as well as bacterial metabolites in the stomach and showed similar nonsignificant modifications in jejunum contents except for acetate in the mono-enzyme group. Total jejunal bile acids were unchanged. Compared to the control, the ratio of the main conjugated to the main deconjugated bile acid was significantly higher in the mono-enzyme group. This study has shown that the mono- and multi-enzyme preparation can lead to improved performance in wheat based diets for piglets. Like in poultry, the main mode of action seems to be the reduction of small intestinal viscosity. However, the generation of fermentable carbohydrates by the multi-enzyme preparation may mask beneficial effects on performance due to the development of an active bile acid deconjugating microbiota in the small intestine.

Compensatory digestion of fat, protein and starch (rates and amounts) in the large intestine of minipigs in case of reduced precaecal digestion due to pancreatic duct ligation — A short review

To generate quantitative ideas about the digestive capacity of the large intestine of pigs in case of reduced precaecal digestion, the results of several studies using the model “pancreatic duct ligated minipig”, are summarised. Ligation of the pancreatic duct causes an exocrine pancreatic insufficiency (EPI) leading to a severe reduction of precaecal digestibility (prc. dig.) rates [Tabeling, R., Gregory, P. Kamphues, J., 1999. Studies on nutrient digestibilities (pre-caecal and total) in pancreatic duct ligated pigs and the effects of enzyme substitution. J. Anim. Physiol. Anim. Nutr. 82, 251–263.]. All minipigs (control pigs; C and pancreatic duct ligated pigs; PL) were surgically fitted with an ileocaecal re-entrant fistula to determine rates and amounts of precaecal and total tract (total) digestion of crude fat (cfa), crude protein (cp) and starch (st). The animals were fed diets rich in starch (StD: ∼ 60% st in dry matter [DM]) or rich in fat (FaD: ∼ 30% cfa in DM). In PL reduced prc. dig. rates, especially of cfa and cp (prc. cfa dig.: C: 88.2–97.6%; PL: 9.3–43.0%; prc. cp dig.: C: 79.1–82.3%; PL: 26.1–40.9%) were found. Digestion of starch was only moderately reduced in PL (prc. st dig.: C: 97.2–99.7%, PL: 61.9–92.5%). Up to 2.6 g of starch and 0.98 g of cp per kg body weight were digested postileally in PL, while postileal cfa digestion was negligible or negative (indicating microbial fat synthesis). Total tract digestibility of st did not differ between C and PL while dig. rate of cp was markedly reduced in PL. The studies permit an evaluation and quantification of the high compensative capacity of the hindgut especially in case of influx of large amounts of starch due to reduced prc. digestibility.

Effect of partial dehulling of two- and six-row barley varieties on precaecal digestibility of amino acids in pigs

Five barrows (German Landrace; initial BW 58 kg, final BW 80 kg) fitted with an ileo-rectal anastomosis were used to determine the effect of partial dehulling and addition of barley hulls of two- and six-row barley varieties on the precaecal digestibility (pD) of CP and amino acids. The following diets were provided according to a standardized diet formulation and tested in seven consecutive periods (repeated group-period design): two-row barley (TRB) + casein (C), dehulled TRB + C, TRB + C + 10% hulls, six-row barley (SRB) + C, dehulled SRB + C, SRB + C + 1% hulls, and wheat starch + C. The diets were supplied at daily rates of 79 – 86 g DMI · kg BW−0.75 in barley containing diets and at 49 g DMI · kg BW−0.75 in the casein diet. The digestibility of amino acids in barley varieties was determined by the difference method (casein as basal diet) using quantitative digesta collection. In both varieties of barley the pD of CP and amino acids did not differ. The pD of CP was unchanged in regard to the treatments in both barley varieties. Due to dehulling in TRB the pD was improved significantly for most indispensable amino acids and in SRB for Met and Cys. Addition of 10% hulls to TRB led to equivalent pD of Arg, His, Leu, Tyr, and Trp compared to TRB, but the pD of Lys, Phe, Thr and Val was significantly decreased below the levels of TRB. Addition of even 1% hulls to SRB impaired the pD of Lys below the level in SRB. In conclusion, addition of barley hulls to pig diets impairs amino acids absorption in the small intestine. The pD values, measured under standardized experimental conditions (without a correction using basal endogenous amino acids), are similar to the values of true digestibility published by NRC (1998).

Influence of pre-, pro-, and synbiotics on the intestinal availability of different B-vitamins

This study was conducted with 16 male growing pigs (eight pigs with an end-to-end ileo-rectal anastomosis, eight intact pigs) to investigate in metabolic trials the influence of different pre-, pro-, and synbiotics on the precaecal and faecal digestibility of thiamin, riboflavin, pantothenic acid and biotin. A basic experimental diet was supplemented with either pre-, pro-, or synbiotic additives as follows: lactulose (2%), inulin (2%), mannanoligosaccharides (0.3%), Enterococcus faecium DSM 10663 (8 · 109 cfu/kg), Enterococcus faecium DSM 7134 (5 · 108 cfu/kg), inulin + Enterococcus faecium DSM 10663, mannanoligosaccharides + Enterococcus faecium DSM 7134. The precaecal and faecal digestibilities of the investigated B-vitamins were not affected significantly by the administered pre-, pro-, and synbiotics independent of the application period. A higher faecal vitamin excretion vs. the precaecal indicated that thiamin and biotin were synthesized in the colon. On the contrary, for riboflavin and pantothenic acid a higher precaecal vitamin flow compared to the faecal excretion was detected indicating to a certain extent an absorption in the colon.

Precaecal and faecal digestibility of inulin (DP 10–12) or an inulin/Enterococcus faecium mix and effects on nutrient digestibility and microbial gut flora

The aim of the present study was to investigate the precaecal and faecal digestibility of inulin (DP 10-12) and inulin/Enterococcus faecium mix, and the effects of these substances on nutrient digestibility and microbial gut flora. For the experiment four of eight male pigs were fitted with an end-to-end ileo-rectal anastomosis (IRA) with preserved ileo-caeco-colic valve. The residual pigs were used as intact partner (IN). The animals received 1.5 kg/day of a diet based on corn, wheat, barley and soybean meal, supplemented with either 8 x 10(9) CFU E. faecium/kg, 2% inulin or a mixture of both substances. The digestibility trial was carried out from weeks 4 to 8 after surgery. Precaecal digestibility of inulin was assessed to be 57%. The addition of E. faecium to the diet resulted in a similar precaecal digestibility of inulin of 55%. Supplementation of E. faecium, inulin, and a mixture of E. faecium and inulin did not affect precaecal and faecal nutrient digestibility with the exception of the precaecal digestibility of CF which increased when inulin alone was supplemented. Bacterial population in the digesta of IRA and IN pigs were not affected by the experimental diets except the concentration of bifidobacteria and lactobacilli. The supplementation of E. faecium to the diet significantly decreased the concentration of bifidobacteria and the population of lactobacilli inclined to decrease when IN pigs received the probiotic diet. The combination of E. faecium and inulin prevented a reduction of enterococci in faeces of IN pigs. The daily digesta excretion (DM) tended to decrease in IRA and IN pigs when inulin was supplemented. The results indicate that inulin (DP 10-12) in pig nutrition did partly react as a prebiotic as has been confirmed for humans. A combination of E. faecium and inulin improves the survival of the probiotic strain through the upper intestinal tract and allocates the synbiotic effect. Furthermore inulin might be able to show positive effects on precaecal and faecal microbial characteristics.

Variation in precaecal amino acid and energy digestibility between pea (Pisum sativum) cultivars determined using a linear regression approach

1. An experiment was conducted to study the variation in the precaecal amino acid (AA) and energy digestibility of 4 cultivars of white-flowering peas (Pisum sativum) for broiler chickens. The 4 cultivars were grown and harvested under the same agronomic and environmental conditions. 2. One basal diet and 8 diets including each pea cultivar at inclusion rates of either 150 or 300 g/kg were used. Peas were included at the expense of starch. Hence, the differences in dietary crude protein and AA concentrations resulted only from the inclusion of peas. Titanium dioxide was included as an indigestible marker. 3. Crude protein concentrations in the complete diets ranged from 164 to 244 g/kg. All diets were fed ad libitum to broiler chickens between 14 and 21 d of age. Seven pens of 12 chickens were allocated to each treatment. Digesta were sampled on a pen basis from the section of the gastrointestinal tract between Meckel's diverticulum and 2 cm anterior to the ileo-caeco-colonic junction. 4. The proportions of crude protein and AAs digested responded linearly to increased intake and the relationships between quantitative intake and digested amounts of AAs were described by multiple linear regressions. The slope determined for each pea cultivar was taken as a measure of AA digestibility without the need for consideration of basal endogenous crude protein and AA secretions. 5. Digestibility of AAs in peas ranged from 0·60 to 0·91. One cultivar had significantly lower AA digestibilities than the other three cultivars. This could be explained neither by the trypsin inhibitor activity nor by tannin levels. The AAs with the highest digestibilities in all cultivars were arginine > glutamic acid > lysine > methionine > phenylalanine > leucine. The AAs with the consistently lowest digestibilities were cystine < threonine. The ranking of the remaining AAs varied slightly between cultivars. 6. The multiple linear regression approach is suitable to study differences in AA digestibilities without the need for consideration of basal endogenous AA losses. 7. Diets containing 300 g/kg of peas had significantly lower energy digestibilities than the pea-free basal diet. The pea cultivar with the lowest AA digestibility caused the lowest energy digestibility at both levels of pea inclusion.

Experiments to optimize enzyme substitution therapy in pancreatic duct‐ligated pigs

Ligation of the pancreatic duct in pigs leads to severe maldigestion and malabsorption of crude nutrients. Supplementation with 24 capsules of Creon (Solvay Pharmaceuticals GmbH, Hannover, Germany) per meal led to an increased digestibility of crude nutrients. With regard to optimization of the treatment of EPI no essential improvements can be achieved by adding omeprazol or lecithin to the diet. In pancreatic duct-ligated pigs the isolated addition of omeprazol led to an increase of the pre-caecal digestibility of crude fat and organic matter. With additional enzyme substitution, the application of omeprazol did not result in an improved fat digestibility. Isolated addition of lecithin to the diet resulted in a reduced total digestibility of crude fat. Offering the diet twice a day and using a higher frequency of enzyme applications (four or six instead of only two applications) had no effects on the digestibilty of crude fat or organic matter. According to the observations in pancreatic duct-ligated pigs, the addition of missing enzymes to the diet led to the best treatment results in EPI. Administration of omeprazol or a higher feeding frequency as well as the application of enzymes in small proportion of the whole meal or dosages given consecutively over the day showed no advantages. Furthermore, the present study suggests that the addition of lecithin cannot be recommended in EPI, when given diets with butter as the predominant fat source as in human dietetics.

Pectin in pig nutrition, a comparative review

A comprehensive review is given on pectin effects in pigs. Its effects on feed passage and digestion in the small intestine, the composition of ileal digesta and fermentation in the colon are described. Pectins promote fermentation at the terminal ileum and in the first part of the colon. It is shown, that pectin opposite to cellulose is degraded to high extents in the colon. Dietetic effects in relation to composition of ileocaecal digesta, endogenous secretions, buffering and pH-stability, high fermentability of organic matter in the colon and resulting volatile fatty acids (VFA) in the cranial part of the colon and even its possible interactions to colonization of the gut by infectious bacteria are described. Pectin effects concerning volume of the intestinal tract, distribution of VFA and lactic acid, role of endogenous secretions are described. The negative effect of pectins on praecaecal digestibility, their high degradation rates in the large intestine and consequences for their dietetic effects are discussed.

Investigation on the precaecal and faecal digestibility of lactulose and inulin and their influence on nutrient digestibility and microbial characteristics

This study was conducted to determine the pre-caecal and faecal digestibility of lactulose and inulin and the influence of these substances on nutrient digestibility and microbial characteristics. In metabolic trials three of six male growing pigs (German Landrace × Pietrain) were fitted with an ileo-rectal anastomosis (IRA) in end-to-end technique with preserved ileo-caeco-colic valve. The metabolic trials were conducted from day 21 – 63 after surgery. The remaining pigs were used as intact partners (IN) for the IRA pigs. The experimental diets, based on corn, wheat, barley and soybean meal, were supplemented with either 1.5% lactulose or 2% inulin in replacement of diatomaceous earth (control). Pre-caecal digestibility of lactulose and inulin was assessed to be 79 and 98%, respectively, faecal digestibility was determined as 100%. The supplementation of lactulose and inulin had only minor effects on the pre-caecal and faecal digestibility of nutrients. Significant differences in nutrient digestibility were obvious between IRA and IN pigs, whereas the IRA pigs showed lower digestibility values with the exception of ether extracts (EE). Bacterial population in the digesta of IRA and IN pigs were not affected by the experimental diets except the concentration of gram-negative anaerobes, which inclined when the IRA pigs received the lactulose diet. The pH of chyme was significantly lower than the pH of faeces, however the pH was unaffected by the different supplemented diets. The concentration of volatile fatty acids (VFA) in pre-caecal chyme decreased significantly when IRA pigs received the lactulose supplemented diet whereas VFA in faeces were unaffected by the supplementation. IRA pigs administered with lactulose excreted more N via the urine, but the nitrogen balance remained unaffected. From the present investigation it can be concluded that lactulose and inulin did only partly or scarcely fulfill the expectation of acting as prebiotics in pigs.

Effect of dehulling of rapeseed on feed value and nutrient digestibility of rape products in pigs

In the presented study the influence of dehulling rapeseed on the composition of rapeseed meal (RM) and rapeseed cake (RC) and on its feed value for piglets and growing-finishing pigs was investigated. Before withdrawal of oil, rapeseed (variety Express) was dehulled applying a procedure developed by SKET GmbH Magdeburg and the Section Food-Technology of the University Essen. The steps of the dehulling procedure were described. For RM the oil was removed by the prepress-solvent procedure till a crude fat content of 2.1% in DM. RC was produced by pressing only resulting approximately 13% crude fat in DM. The RM and RC from not dehulled (ND) and dehulled (D) rapeseed were examined analytically. Crude nutrients, sugar and fibre substances, amino acids, some minerals and trace elements, fatty acids, glucosinolates and sinapine, and phytate were determined. By dehulling the seed the crude fibre content was decreased in RM and RC by approximately 40%. The ADF content declined by 35 and 39%, and the NDF content by 28% and 40% in RM and RC, respectively. The decrease in ADL content amounted to 50% and 65% for RM and RC, respectively. On the other hand, the CP content of RM and RC was increased by 7% and 13%, respectively, by dehulling the seed while the amino acid content of rape protein increased only slightly. The contents of glucosinolates and sinapine were also increased by dehulling, while the contents of phytate and phytate P were decreased. In digestibility and balance experiments with piglets and intact hybrid breeds of growing-finishing pigs, the digestibility of organic matter and of crude nutrients and the contents of digestible energy and metabolizable energy were estimated. Furthermore, the precaecal digestibility of crude nutrients and amino acids was determined with fistulated mini-pigs. By dehulling the seeds the digestibility of organic matter from RM and RC was improved in piglets and adult pigs by approximately 10%, and the ME contents increased by 13 – 15%. The precaecal digestibility of the sum of amino acids was increased by approximately 3 and 6 units in RM and RC, respectively. The precaecal digestibility of lysine in RM and RC reached that of soybean oil meal from not dehulled beans.

Influence of Supplemental Enzymes, Yeast Culture and Effective Micro-organism Culture on Gut Micro-flora and Nutrient Digestion at Different Parts of the Rabbit Digestive Tract

An experiment of 10 weeks duration was carried out to study the influence of supplemental effective microorganism (EM) culture, yeast culture and enzymes on nutrient digestibility and gut microflora in rabbit gastrointestinal (GI) tract. Twenty four eight to nine weeks old, New Zealand White rabbits were allotted to four dietary treatments; a basal (control) feed, basal feed supplemented with either EM (1%), yeast culture or enzymes (400 ppm). Nutrient flow in digesta and their digestibility at ileum, caecum, colon and in the total tract as well as gut microflora distribution were studied. Feed dry matter was diluted from 92% to about 14% up to the ileum and about 95% of this water was reabsorbed by the colonic rectal segment followed by caecum (25%). EM and yeast improved protein digestibility at a lower rate than enzymes. Ileal, caecal, colonic and total tract digestibility of crude protein with enzymes were higher by 10.8, 9.4, 11.3 and 10.7%, respectively, as compared to the control. Yeast and enzymes increased crude fiber digestibility at ileum, caecum, colon and in the total tract by 8.5, 9.6, 9.0 and 8.3%, respectively, while EM improved them at a lower rate. Irrespective of treatments, total tract digestibility of crude protein (0.698-0.773) and fiber (0.169-0.183) were greater (p<0.05) than the ileal digestibility. Even though a post-caecal protein digestibility was observed, fiber digestion seemed to be completed in the caecum especially with yeast and enzymes. High precaecal digestibility of crude fiber (97%) and protein (95%) were observed even without additives probably due to caecotrophy. EM and yeast culture promoted the growth of lactic acid bacteria especially in the caecum but they did not influence gut yeast and mould. Present findings reveal that even though rabbits digest nutrients efficiently through hind gut fermentation, they can be further enhanced by EM, yeast and enzymes. Of the three additives tested, enzymes found to be the best. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 6 : 830-835)

Apparent Precaecal Digestibility of Nutrients and Level of Endogenous Nitrogen in Digesta of the Small Intestine of Growing Pigs as Affected by Various Digesta Viscosities

Sixteen male growing pigs of about 24kg BW were fitted with both a duodenal re-entrant and a post-valve T-shaped cannula inserted in the caecum. The animals were divided into four groups. Each group received one of the following diets: corn starch-soybean protein isolate-based diet without (diet C) and with carboxymethylcellulose (diet CMC) or a rye-wheat-based diet without (diet RW) and with xylanase addition (diet RWX). The diets provided similar levels of apparent precaecal digestible crude protein (CP), lysine, methionine+cystine, threonine and tryptophan. Additionally, [15N]-yeast was given with the diets during the first 10 days of the experiment. For estimation of digesta viscosity, N-flow of dietary and endogenous origin, apparent precaecal digestibilities of dry matter (DM), CP, amino acids and non starch polysaccharides (NSP) (only in pigs fed diets RW and RWX), ileal and duodenal digesta were quantitatively collected on day 16 and 17, respectively. The endogenous N-proportion was measured by the ratio of 15N enrichment in the digesta and urine. The duodenal and ileal digesta supernatant viscosity increased as carboxymethylcellulose was included into the diet. Xylanase addition to the rye-wheat based diet reduced the viscosity in the ileal digesta. There were no differences in precaecal digestibilities of DM, CP and amino acids between diet C and CMC. The precaecal digestibilities of DM and soluble and insoluble NSP increased from 69.5% to 73.9%, from 1.3% to 47.9% and from 17.0% to 35.4%, respectively, as xylanase was added to the rye-wheat-based diet. The apparent precaecal digestibility of most essential amino acids increased by 2 to 5 percent units. The amounts of endogenous N at the duodenal level were estimated to be 158, 233, 313 and 276mg per 12h per kg0.75 BW of pigs fed diets C, CMC, RW and RWX, respectively. The corresponding values at the ileal level were 95, 107, 164 and 150mg per 12h per kg0.75 BW. For endogenous N amounts, significant differences were observed between diets C and CMC (duodenum) and also between semi-purified and cereal-based diets (duodenum and ileum). Methodological aspects for the estimation of endogenous N using the isotope dilution technique are discussed. Obviously, the digesta viscosity per se does not affect the nutrient absorption and endogenous N flow within the small intestine of pigs. Other properties of complex dietary fibre, digesta passage rate or bacterial activity probably contribute to the observed changes.

Availability of vitamin B 6 from different food sources

The present study was conducted to investigate the precaecal digestibility of vitamin B 6 from selected food sources including eggs, bananas, white cabbage, corn, milk powder, fish, barley, soybeans, brown rice, wheat bran, brewer's yeast, rye and soybean meal. These foods were chosen for their relevance in human and animal nutrition and prepared as they are usually eaten by humans. As confirmed by further investigations the precaecal digestibility is a valuable measure for determining the availability of native B-vitamins. Therefore, pigs were fitted with an end-to-end ileo-rectal anastomosis for digesta passing straight from ileum to rectum, thus avoiding endogenous vitamin synthesis by the colon. Three weeks after surgery the digestibility experiments were carried out during which the animals were fed various experimental diets for a period of 12 days and digesta were collected quantitatively twice a day during the final 5 days of this period. The concentration of vitamin B 6 in foods and chyme was determined by high pressure liquid chromatography. Precaecal digestibility of vitamin B 6 from all tested food sources ranged from 51 to 91% in the following order: cabbage diet > banana diet > fish diet > milk powder diet > brewer's yeast diet > soybeans diet > soybean meal diet > egg diet/corn diet > barley diet > wheat bran diet > rye diet. Only boiled brown rice had a very low vitamin B 6 availability of 16%. The digestibility of vitamin B 6 from plant products (excluding the rice) was on average 10% lower when compared with animal products (71 versus 79%).

Effect of soy oil supplementation and protein level in laying hen diets on praecaecal nutrient digestibility, performance, reproductive performance, fatty acid composition of yolk fat, and on other egg quality parameters

An experiment was carried out with laying hens in the age of 22—45 weeks to examine the effects of added soy oil (0%, 3.5%, 7%, 10.5%, and 14%) and dietary protein level (13.2% and 16.3%) on laying and reproductive performance, fatty acid composition of yolk fat, and other egg quality parameters. Moreover, digestibility of nutrients and of energy was determined by using a marker technique. Laying intensity and feed intake were not influenced by dietary treatments whereas egg weight and daily egg mass production were significantly improved by soy oil addition in a non-linear related manner. The feed conversion ratio reached a minimum at soy oil proportions between 3.5% and 10.5%. Reproductive performance in terms of fertilized eggs, hatchability, and mortality of chicks was not affected by dietary treatments. The increase of egg weights due to soy oil addition was accompanied by a simultaneous increase in the proportion of albumen and a decrease of yolk and shell percentage. Palmitic acid (C16:0) and oleic acid (C18:1) proportions in yolk fat decreased as soy oil addition was increased whereas the proportions of linoleic acid (C18:2 n-6), linolenic acid (C18:3 n-3), and docosahexaenoic acid (C22:6 n-3) were increased at the same time. Praecaecal digestibility of crude fat and fatty acids of the diets were non-linearly improved by soy oil addition. Digestibility of crude protein and amino acids were not affected by either protein content of the diet or by soy oil supplementation. In conclusion, a decrease in dietary protein content from 16.3% to 13.2% did not negatively influence performance of hens and egg quality under the experimental conditions applied. Soy oil addition improved egg quality.

Effect of soy oil supplementation and protein level in laying hen diets on praecaecal nutrient digestibility, performance, reproductive performance, fatty acid composition of yolk fat, and on other egg quality parameters

An experiment was carried out with laying hens in the age of 22—45 weeks to examine the effects of added soy oil (0%, 3.5%, 7%, 10.5%, and 14%) and dietary protein level (13.2% and 16.3%) on laying and reproductive performance, fatty acid composition of yolk fat, and other egg quality parameters. Moreover, digestibility of nutrients and of energy was determined by using a marker technique. Laying intensity and feed intake were not influenced by dietary treatments whereas egg weight and daily egg mass production were significantly improved by soy oil addition in a non-linear related manner. The feed conversion ratio reached a minimum at soy oil proportions between 3.5% and 10.5%. Reproductive performance in terms of fertilized eggs, hatchability, and mortality of chicks was not affected by dietary treatments. The increase of egg weights due to soy oil addition was accompanied by a simultaneous increase in the proportion of albumen and a decrease of yolk and shell percentage. Palmitic acid (C16:0) and oleic acid (C18:1) proportions in yolk fat decreased as soy oil addition was increased whereas the proportions of linoleic acid (C18:2 n-6), linolenic acid (C18:3 n-3), and docosahexaenoic acid (C22:6 n-3) were increased at the same time. Praecaecal digestibility of crude fat and fatty acids of the diets were non-linearly improved by soy oil addition. Digestibility of crude protein and amino acids were not affected by either protein content of the diet or by soy oil supplementation. In conclusion, a decrease in dietary protein content from 16.3% to 13.2% did not negatively influence performance of hens and egg quality under the experimental conditions applied. Soy oil addition improved egg quality.

Precaecal digestibility of niacin and pantothenic acid from different foods.

This study was conducted to investigate the apparent precaecal digestibilities of niacin and pantothenic acid from human nutrient related foods including wheat, coarse whole-meal bread, boiled potatoes and boiled pork and beef. Therefore, pigs were subjected to an end-to-end ileo-rectal anastomosis, so digesta passed straight from ileum to rectum, eliminating endogenous vitamin synthesis. Excreted chyme was collected over 5-days periods, and concentrations of niacin, and pantothenic acid in the food and chyme samples were determined microbiologically. The intestinal bioavailability of niacin and pantothenic acid was affected differently by the food administered. The digestibility values of niacin deriving from the wheat-, potato- and the meat-based meals ranged from 59 to 69%. Wholemeal bread exerted a nutritionally important negative effect on the apparent intestinal availability of dietary niacin relative to the other foods, which averaged by 40%. Food-related differences of the pantothenic acid digestibility values were greater than that observed with niacin. The digestibility values of pantothenic acid from wheat, potatoes and the meat meals ranged between 65 and 81% and were of the order wheat diet > pork diet > potato diet > beef diet, although differences were not statistically significant. The digestibility of pantothenic acid from the coarse wholemeal bread diet was lower than 30%.

Investigations on the intestinal availability of native thiamin in selected foods and feedstuffs.

The aim of the present study was to investigate the precaecal digestibility as a quantitative measure for the intestinal availability of naturally occurring thiamin from selected foods and feedstuffs. Therefore, three experiments were conducted to examine the following foods and feedstuffs: Eggs, bananas, white cabbage, corn, milk, fish, barley, soybeans, rice, wheat bran, brewer's yeast, rye and soybean meal. The foods and food processing procedures were made with regard to their relevance in human and animal nutrition. For all experiments male pigs with an initial live weight between 33 and 40 kg were fitted with an end-to-end ileo-rectal anastomosis with preserved ileo-caeco-colicvalve. Three weeks after surgery, the digestibility trials were carried out from week 4 to week 9 and week 12 to week 17 after surgery. The animals were fed the individual experimental diets for a period of 12 days while digesta were collected twice a day quantitatively during the final 5 days of this period. Precaecal digestibility for thiamin from all tested foods and feedstuffs was within a range from 73% to 94% with the highest values from boiled soybeans, boiled rice and barley, and the lowest value from steamed fish. In comparison with the animal products the plant products show on average a nearly equal precaecal digestibility for thiamin (87.3% versus 83.5%). Moreover, all tested foods and feedstuffs exhibit a relatively good intestinal availability of thiamin.

A comparative evaluation of ileo‐rectal anastomosis techniques for the measurement of apparent precaecal digestibilities of folate, niacin and pantothenic acid

Introduction There is a great need for better understanding of the intestinal bioavailability of B‐vitamins and the factors that influence it. In food products, however, nutrient content does not necessarily imply the proportion of nutrient content actually absorbed. Thus a variety of experimental approaches have been used for determining the intestinal bioavailability of food vitamins. They include measuring changes in tissue vitamin levels, urinary vitamin excretion and growth in response to known intakes of vitamin‐containing foods (e.g. Southern and Baker 1981; Gregory and Litherland 1986; Abad and Gregory 1987; Clifford et al. 1990; Swatilo et al. 1990; Yu and Kies 1993; Matte and Girard 1994). Potential limitations of those animal bioassays centre mainly on the role of the intestinal microflora and the extent of enhancement or inhibition of their vitamin synthesis by dietary components. The endogenous vitamin synthesis by the intestinal flora, with possible uptake in the distal part of the small and/or large intestine, is a complicating factor for nearly all B‐vitamins. The components of test diets that would stimulate the synthesis of B‐vitamins by intestinal microorganisms could therefore cause overestimation of dietary vitamin availability in conventional bioassays. Application of in‐vitro assays has also been reported for water‐soluble vitamins, but these are not recommended because of the limitations in extrapolation of the results to the situation in vivo (Holler et al. 1975; Seyoum and Selhub 1998). In principle, methods using stable isotopes will give the most reliable information concerning intestinal absorption, but their application is still limited, mainly because stable isotopes are not commercially available and specialized facilities and expertise are required. Ileo‐rectal anastomosis has been proposed as an alternative method for calculating the intestinal availability of nutrients (Herrmann et al. 1988; Green and Kiener 1989; Laplace et al. 1989; Hennig et al. 1990; Roth‐Maier et al. 1998). The most important advantage of ileo‐rectal anastomosis for measuring vitamin digestibility is the prevention of vitamin synthesis by the intestinal microflora and coprophagy, because the digesta can be collected quantitatively via the anus. In this respect two different techniques of ileo‐rectal anastomosis have been developed for pigs: the end‐to‐side (ESV) and end‐to‐end (EEV) ileo‐rectal anastomosis with preserved ileo‐caeco‐colic valve. Both methods have already been compared for their use as digestibility assays for the vitamins including thiamin, riboflavin and vitamin B6 (Roth‐Maier et al. 1998). The objective of the present study was to compare both the ESV and EEV techniques with regard to the digestibility values of folate, niacin and pantothenic acid, which has not been tested hitherto. In addition, in order to examine age‐ or time‐related effects on vitamin digestibility two different experimental periods after surgery were chosen for measurement.

Comparative studies for the determination of precaecal digestibility as a measure for the availability of B‐vitamins

ZusammenfassungVergleichende Untersuchungen zur Bestimmung der praecaecalen Verdaulichkeit als Maß für die Verfügbarkeit von B‐VitaminenZiel der vorliegenden Untersuchungen war zwei Techniken der Methodik der Ileorectal‐Anastomose (IRA) zur quantitativen Ermittlung der Verfügbarkeit von nativen B‐Vitaminen für Mensch und monogastrische Tiere zu testen. Hierfür wurden bei 9 weiblichen Schweinen der Deutschen Landrasse Ileorectal‐Anastomosen gelegt um die praecaecale Verdaulichkeit als Maß für die Verfügbarkeit zu bestimmen. Die Ileorectal‐Anastomosen wurden in End‐zu‐Seit‐ (ESV, 3 Tiere) bzw. in End‐zu‐End‐Ausführung (EEV, 6 Tiere) bei Erhalt der Ileocaecalklappe hergestellt. Mit den operierten Tieren wurden Stoffwechselversuche durchgeführt und die praecaecale Verdaulichkeit von Thiamin, Riboflavin und Vitamin B6 in Weizen, Vollkornbrot, gekochten Kartoffeln, gegartem Schweine‐ und Rindfleisch gemessen.Die praecaecale Verdaulichkeit von Thiamin betrug bei den ESV/EEV‐Tieren 75/78% in Weizen, 60/75% in Vollkornbrot, 63/84% in gekochten Kartoffeln, 93/96% in gegartem Schweinefleisch und 51/79% in gegartem Rindfleisch. Die Werte fhr Riboflavin lagen bei 58/71% in Schweinefleisch und 31/87% und 86/89% in Weizen, Vollkornbrot, Kartoffeln, Schweine‐ und Rindfleisch verdaulich.Die Verdaulichkeit war bei dem EEV‐Tieren jeweils deutlich höher. Das bedeutet, daß bei der ESV‐Methode ein gewisser Rückfluß von Digesta in das Colon auftritt und mikrobiell synthetisierte B‐Vitamine mit dem ilealen Chymus ausgeschieden werden. Deshalb ist für die B‐Vitamine die EEV‐Technik anzuwenden. Der Zeitvergleich mit Weizen über die Messung der Verdaulichkeit in den Perioden 4.‐9. Woche und 12.‐17. Woche nach der Operation ergab identische Ergebnisse, so daß dieser gesamte Versuchszeitraum für Messungen verwendet werden kann.Die Kombination aus Bruttovitamingehalt und Verfügbarkeit erlaubt die Lebens‐/Futtermittel als Vitaminlieferanten zu beurteilen. Schweinefleisch überragt die anderen Produkte als Thiaminlieferant (52% des Tagesbedarfs durch 100 g eßbares Produkt), Riboflavin wird am meisten durch Schweinefleisch (10%) und Vitamin B6 am besten durch Schweine‐ und Rindfleisch (25%) geliefert.Diese Untersuchungen wurden mit Unterstützung der DFG durchgeführt.