Diurnal variation in insulin-stimulated systemic glucose and amino acid utilization in pigs fed with identical meals at 12-hour intervals.

The diurnal variation in insulin-stimulated systemic glucose and amino acid utilization was investigated in eleven pigs of approximately 40 kg. Pigs were fed isoenergetic/isoproteinic diets (366 kJ/kg BW (0.75) per meal) in two daily rations (06:00 and 18:00 h). After a 3-week habituation period, hyperinsulinemic euglycemic euaminoacidemic clamp studies (by intra-portal insulin, glucose and amino acids infusion and arterial blood sampling) were performed starting at 06:00 or 18:00 h (while skipping the meal), using a cross-over within-animal design. Basal (preclamp) plasma concentrations of insulin, glucose, lactate, individual amino acids and urea were similar in the morning compared to the evening. Insulin-stimulated ( approximately 4-fold increase over basal) systemic glucose utilization was similar (17.6+/-1.4 and 18.9+/-1.8 mg x kg (-1) x min (-1)) but amino acid utilization was 19% greater in the morning VS. the evening (2.37+/-0.21 VS. 1.99+/-0.15 mg x kg (-1) x min (-1), p<0.05), respectively. Insulin-stimulated plasma lactate concentrations remained constant in the morning (0.77+/-0.06 to 0.71+/-0.04 mmol x l (-1)) but declined in the evening (0.89+/-0.09 to 0.65+/-0.06 mmol x l (-1), p<0.05). By contrast, insulin-stimulated plasma urea concentrations declined in the morning (2.48+/-0.11 to 2.03+/-0.10 mmol x l (-1), p<0.005) but remained constant in the evening (2.18+/-0.14 to 2.12+/-0.12 mmol x l (-1)). In conclusion, pigs fed identical meals at 12-hour intervals follow a clear diurnal biorhythm in protein anabolism, with greater insulin-stimulated systemic amino acid utilization and lower plasma urea response in the morning compared to the evening.

Physiology, regulation and multifunctional activity of the gut wall: a rationale for multicompartmental modelling.

A rationale is given for a modelling approach to identify the mechanisms involved in the functioning and metabolic activity of tissues in the wall of the gastrointestinal tract. Maintenance and productive functions are discussed and related to the distinct compartments of the gastrointestinal tract and the metabolic costs involved. Functions identified are: tissue turnover; tissue proliferation; ion transport; nutrient transport; secretions of digestive enzymes, mucus and immunoglobulins; production of immune cells. The major nutrients involved include glucose, amino acids and volatile fatty acids. In vivo measurements of net portal fluxes of these nutrients in pigs and ruminants are evaluated to illustrate the complexity of physiology and metabolic activity of the gastrointestinal tract. Experimental evidence indicates that high, but variable and specific, nutrient costs are involved in the functioning of the gastrointestinal tract.

The effects of potassium diformate and its molecular constituents on the apparent ileal and fecal digestibility and retention of nutrients in growing-finishing pigs.

Five 43-kg barrows [(Dutch Landrace x Yorkshire) x Yorkshire] were fitted with steered ileocecal valve cannulas to compare the effects of K-diformate (KDF), a specifically conjugated salt vs its molecular constituents, namely, formic acid and K-formate, as acidifiers in lysine-deficient diets on the apparent ileal (ID) and fecal digestibility, retention of nutrients, and manure production. The animals were randomly assigned to five dietary treatments according to a 5 x 5 Latin square design as follows: 1) control-no acidifier; 2) 1% KDF (= 0.65% K-formate + 0.35% formic acid, or 0.7% [HCOO-] + 0.3% [K+]); 3) 0.65% K-formate (= 0.35% [HCOO-] + 0.3% [K+]); 4) 0.35% formic acid (= 0.35% [HCOO-]); and 5) 1.3% K-formate (= 0.7% [HCOO-] + 0.6% [K+]). Diets were formulated with barley, wheat, soybean meal, and canola meal as major ingredients, and provided all nutrients at adequate levels, except for lysine (24% less than estimated requirement). Feeding level was equal to 2.5 x maintenance requirement (MR) for ME (MR = 418 kJ ME x BW(-0.75)), and daily rations were given in two portions after mixing with water in a ratio of 1:2.5. Chromic oxide was used as an indigestible marker. No clinical health problems due to the dietary treatments were observed. Irrespective of the additive, there were no differences (P < or = 0.10) in the ID of DM, OM, CP, or essential amino acids compared to the control, except for phenylalanine (P < or = 0.05). Among nonessential AA, only the ID of tyrosine tended (P = 0.092) to increase (up to 3.9 percentage units). The fecal digestibility of ash and K were greater (P < or = 0.001) in pigs fed supplemental K, irrespective of its source. The greater intake and fecal digestibility of K corresponded with greater (P < or = 0.05) losses of K in urine. Body retention of N, Ca, total P, and K was similar (P > or = 0.10) among treatments. As estimated from a separate nonorthogonal analysis, supplemental K improved (P < or = 0.05) body N by 3.7 percentage units compared to the control. The results of this study do not provide a clear explanation for the improved growth performance reported previously with KDF and its molecular constituents, and further research on their in vivo mode of action will require methodological refinement, especially with regard to the efficiency of AA utilization.

The effects of calcium benzoate in diets with or without organic acids on dietary buffering capacity, apparent digestibility, retention of nutrients, and manure characteristics in swine.

Eight barrows (Yorkshire x [Finnish Landrace x Dutch Landrace]), initially 30 kg BW, were fitted with ileal cannulas to evaluate the effects of supplementing Ca benzoate (2.4%) and organic acids (OA) in the amount of 300 mEq acid/kg feed on dietary buffering capacity (BC), apparent digestibility and retention of nutrients, and manure characteristics. Swine were allotted in a 2 x 4 factorial arrangement of treatments according to a cyclic (8 x 5) changeover design. Two tapioca-corn-soybean meal-based diets were formulated without and with acidogenic Ca benzoate. Each diet was fed in combination with OA (none, formic, fumaric, or n-butyric acid). Daily rations were equal to 2.8 x maintenance requirement (418 kJ ME/BW(.75)) and were given in two portions. Chromic oxide (.25 g/kg) was used as a marker. On average, Ca benzoate lowered BC by 54 mEq/kg feed. This salt enhanced (P < .05) the ileal digestibility (ID) of DM, OM, arginine, isoleucine, leucine, phenylalanine, alanine, aspartic acid, and tyrosine (by up to 2.4 percentage units). Also, the total tract digestibility (TD) of DM, ash, Ca and GE, and Ca retention (percentage of intake) was greater (P < .05) in swine fed Ca benzoate, whereas N retention remained unaffected. Addition of all OA (formic and n-butyric acid, in particular) exerted a positive effect (P < .05) on the ID of amino acids (except for arginine, methionine, and cysteine). A similar effect (P < .05) was found for the TD of DM, OM, CP, Ca and total P and for the retention of N and Ca. In swine fed Ca benzoate, urinary pH decreased by 1.6 units (P < .001). In conclusion, dietary OA have a beneficial effect on the apparent ileal/total tract nutrient digestibilities, and Ca benzoate increased urine acidity, which could be effective against a rapid ammonia emission from manure of swine.

Effects of dietary carbohydrates and buffering capacity on nutrient digestibility and manure characteristics in finishing pigs.

A 2 x 3 factorial experiment was conducted with 24 finishing pigs (Yorkshire x [Finnish Landrace x Dutch Landrace]) to determine the effects of dietary buffering capacity (BC) and carbohydrate sources on apparent total tract digestibility (TD), N retention, and manure characteristics. Twelve of these pigs were fitted with steered ileo-cecal value cannulas to measure the apparent ileal digestibility (ID) of N. Experimental variables were two levels of BC (High = 600 mEq/kg and Low = 530 mEq/kg) and three dietary carbohydrates (tapioca [28%], soybean hulls [25%], and sugar beet pulp [25%]). The two levels of BC were achieved by adjusting the amounts of alkalogenic limestone and acidogenic Ca sulfate in the diet. Pigs were fed twice daily at 2.4 x maintenance requirement for metabolizable energy (418 kJ ME/BW(0.75)). Chromic oxide was used as an indigestible marker. Feces and urine were collected over 5 d for nutrient balance and in vitro measurements of pH and ammonia emission over 7 d. No significant interactions between BC and dietary carbohydrates on the ID, TD, N retention, or manure characteristics were observed. Lowering BC with Ca sulfate did not affect digestibility of most nutrients, except for a negative impact on the TD of Ca (P = 0.015) and Mg (P = 0.003). Although all pigs receiving Ca sulfate had more acidic urine (by 0.49 pH units; P = 0.001), ammonia emission from manure was not lowered, irrespective of the carbohydrate source. Carbohydrates affected significantly the ID and TD of most nutrients, whereas N retention remained similar (P > 0.10). Urinary N:fecal N ratios in manure of pigs fed diets with tapioca, soybean hulls, and beet pulp were 2.09, 1.35, and 1.67, respectively. These ratios corresponded with in vitro ammonia emission (169, 125, and 148 mmol/7 d; P = 0.023). In conclusion, these results indicate that the acidification of urine in pigs fed Ca sulfate in the presence of NSP-rich carbohydrates was achieved. However, acidity of manure and ammonia emission were not affected. The addition of NSP from soybean hulls and(or) sugar beet pulp reduced ratios of urinary:fecal N, and thereby ammonia emission.

Quantification of inositol phosphates using (31)P nuclear magnetic resonance spectroscopy in animal nutrition.

A (31)P NMR method for quantitative determination of inositol phosphates in simple incubation samples of sodium phytate and Aspergillus niger phytase and in different types of complex samples, such as diets, digesta, and feces, is described. The inositol phosphates in complex samples were extracted with HCl, concentrated, and purified using freeze-drying and filtration and subsequently determined at pH 12.6 in aqueous solution using a (31)P NMR method. The (31)P NMR technique has as its main advantages over the HPLC techniques that it does not necessitate standards that may cause background matrix effects and that the spectra of inositol phosphates and orthophosphate appear in the same run without further sampling errors. The results of inositol hexaphosphate analysis with HPLC can be confirmed by this (31)P NMR method. Contents of inositol tetra-, tri-, di-, and monophosphate in the biological samples appear to be quantitatively not important. The (31)P NMR method can be applied for use in animal nutrition in general and studies of using phytase in diets for farm animals in particular, by measuring the content of inositol phosphates in feed ingredients, complete feeds, ileal contents, and feces of pigs and poultry.

Organic acids for performance enhancement in pig diets.

Organic acids and their salts appear to be potential alternatives to prophylactic in-feed antibiotics and growth promoters in order to improve the performance of weaned piglets, fattening pigs and reproductive sows, although their growth-promoting effects are generally less than that of antibiotics. Based on an analysis of published data, the growth-promoting effect of formates, fumarates and citrates did not differ in weaned piglets. In fattening pigs, formates were the most effective followed by fumarates, whereas propionates did not improve growth performance. These acids improved the feedgain ratio of both weaned piglets and fattening pigs. In weaned piglets, the growth-promoting effects of dietary organic acids appear to depend greatly on their influence on feed intake. In sows, organic acids may have anti-agalactia properties. Successful application of organic acids in the diets for pigs requires an understanding of their modes of action. It is generally considered that dietary organic acids or their salts lower gastric pH, resulting in increased activity of proteolytic enzymes and gastric retention time, and thus improved protein digestion. Reduced gastric pH and increased retention time have been difficult to demonstrate, whereas improved apparent ileal digestibilities of protein and amino acids have been observed with growing pigs, but not in weaned piglets. Organic acids may influence mucosal morphology, as well as stimulate pancreatic secretions, and they also serve as substrates in intermediary metabolism. These may further contribute to improved digestion, absorption and retention of many dietary nutrients. Organic acid supplementation reduces dietary buffering capacity, which is expected to slow down the proliferation and|or colonization of undesirable microbes, e.g. Escherichia coli, in the gastro-ileal region. However, reduced scouring has been observed in only a few studies. As performance responses to dietary organic acids in pigs often varies, more specific studies are necessary to elucidate an explanation.

Impact of nutrition on reduction of environmental pollution by pigs: an overview of recent research.

This paper focuses on research with pigs carried out primarily at the ID-DLO in the Netherlands with the aim to reduce environmental pollution with nitrogen and phosphorus by changing the diet of the animals while maintaining their health and performance. The excretion of phosphorus (P) per growing pig has been more than halved in the last 20 years as a result of intensive nutritional research on P digestibility, requirements for P, and on the efficacy of microbial phytase in pig feeds. Also, nitrogen (N) excretion can be reduced substantially, but this knowledge has not been put into practice as yet. Preliminary results show that ammonia production can be reduced considerably by altering the diet. Studies to reduce the overproduction of sow manure (up to 98% water) showed that voluntary water consumption by non-pregnant sows under thermal neutral conditions was approximately 1.4 higher than the requirements. A water:feed ratio of 2:1 for pregnant sows kept at an ambient temperature of 18-20 degrees C had no detrimental effect on health and nutrient digestibility, but diminished urine production by 3.6 L/day, as compared to that with ad libitum water consumption.

The efficacy of Aspergillus niger phytase in rendering phytate phosphorus available for absorption in pigs is influenced by pig physiological status.

We performed an experiment with 112 piglets, 32 growing-finishing pigs, and 12 sows during pregnancy and lactation to test the hypotheses that apparent total tract digestibilities of P and Ca as well as the efficacy of Aspergillus niger phytase in rendering phytate P available in pigs depend on pig physiological status. All pigs were fed diets with identical feedstuff composition either without or with added microbial phytase (Natuphos, 500 FTU/kg diet). The diets contained 6.2 g Ca, 4.8 g total P, and 3.7 g phytate P per kilogram, and intrinsic phytase activity of 120 FTU/kg. The digestibility of P increased by 8.3 percentage units when BW of pigs increased from 30 to 60 kg and then remained stable until 100 kg. Pregnant sows had a lower efficiency of P absorption than piglets and growing-finishing pigs. During lactation, the efficiency of P absorption was 3.4 percentage units higher than during pregnancy but was still 6.6 percentage units lower than for growing-finishing pigs. The efficacy of the phytase in generating digestible P decreased in the order or lactating sows, growing-finishing pigs, sows at the end of pregnancy, piglets, and sows at midpregnancy; the average amounts of generated digestible P were 1.03, .83, .74, .66, and .32 g/kg diet, respectively. The addition of phytase to the diet raised apparent Ca digestibility in the piglets and growing-finishing pigs (by 4.6 and 4.0 percentage units, respectively) but not in the sows. We conclude that in the formulation of swine diets the amount of phytase to be added should be tailored to the target category.

Factors affecting phosphorus and calcium digestibility in diets for growing-finishing pigs.

In two experiments, we investigated various factors that affect the estimation of the apparent total tract digestibility (ATTD) of DM, Ca, and total P in diets for growing-finishing pigs. In Exp. 1, the effects of age, housing, and calculation method (indicator [Cr2O3] vs 10-d total collection) were determined. Eighteen barrows and gilts (40 to 95 kg BW) were housed in six pens, and ATTD was estimated using the indicator method. Twelve barrows were housed in metabolic crates, and ATTD was estimated using both calculation methods. Dietary treatments were 1) a tapioca-soybean-barley-based diet, 2) Diet 1 supplemented with 400 FTU microbial phytase/kg of diet, and 3) a corn-soybean meal-based diet: In Exp. 2, six barrows (95 to 120 kg BW) were fed a phytase-deficient diet to investigate the effects of coprophagy (40 g fresh feces/kg of diet) and movement. Pigs were fed at 2.8 times maintenance requirement (418 kJ ME/BW.75); water supply was 2.5 L/kg of feed. The ATTD increased as BW increased. Phytase enhanced total P ATTD by an average of 18.1 percentage units. The ATTD of DM was higher and the ATTD of Ca and total P (P < .001) were lower in pigs housed in pens than in pigs housed in metabolic crates. Fecal consumption and movement led to numerical increases in Ca (P = .217) and total P (P = .103) ATTD. Estimates of Ca and total P ATTD using pigs in metabolic crates are lower than estimates in practice.

The effects of sow parity on digestibility of proximate components and minerals during lactation as influenced by diet and microbial phytase supplementation.

Ninety-six (Finnish Landrace x Dutch Landrace) reproductive sows were used at parities 1, 3, 5, and 7 + 8 from d 107 of gestation to d 21 of lactation to investigate the effects of diet and parity on apparent total tract digestibility (ATTD). Animals were randomly assigned to one of four dietary treatments. Dietary treatments were 1) a P-deficient (1.1 g digestible P [dP]/kg) Dutch semipractical diet; 2) Diet 1 supplemented with 400 FTU Aspergillus niger phytase per kilogram of diet (1.7 g dP/kg); 3) a corn-soybean meal-based diet (1.3 g dP/kg); and 4) Diet 3 supplemented with extra monocalcium phosphate (MCP; 2.4 g dP/kg of diet). Animals were fed twice daily at 2.8 times maintenance (418 kJ ME/ BW75) from d 8 to the end of lactation. Feces and urine were collected during d 11 to 13 and d 18 to 20 of lactation. The ATTD of DM, OM, ash, CP, Ca, Mg, and total P (P < .01) were higher for the corn-soybean meal-based diets than for the Dutch semipractical diet not supplemented with phytase. Addition of MCP enhanced total P ATTD by an average of 6.7 percentage units. Addition of microbial phytase improved Ca, Mg, and total P ATTD, but the effects were dependent on the stage of lactation. Lower ATTD of OM and CP were seen for first parity animals compared with higher parity sows. The ATTD of Mg increased with increasing parity. Parity had little effect on the ATTD of minerals during lactation, and dietary effects were prominent and followed a similar trend to those seen in growing-finishing pigs.

Apparent digestibility of nutrients in diets with different energy density, as estimated by direct and marker methods for pigs with or without ileo-cecal cannulas.

The objective of this study were a) to compare the apparent total tract digestibility (TD) between non-cannulated (intact) and cannulated (steered ileo-cecal valve technique, SICV) pigs fed diets differing in energy density (Exp. 1) and b) to compare the direct vs marker (Cr2O3) methods for estimation of the TD and apparent ileal digestibility (ID) in SICV-cannulated pigs (Exp. 2). In Exp. 1, 24 intact and 18 SICV-cannulated castrates of approximately 40 kg initial BW were randomly assigned to six treatments in a 2 x 3 x 2 factorial arrangement (two pig types, three carbohydrate sources, and two fat levels). In Exp. 2, the same SICV-cannulated pigs from Exp. 1 were given those treatments in a 2 x 3 x 2 factorial arrangement (two methods of digestibility estimation, three carbohydrates sources, and two fat levels). In both experiments either cornstarch, soybean hulls, or pure cellulose, without or with fat, were incorporated into a barely-soybean meal based diet to alter energy density. Daily diets were isoenergetic (based on NEf), and water supply was .33 L/MJ of NEf. In Exp. 1, the pig type effect on the TD of DM, OM, CP, and the pig type x carbohydrate interactions for the TD of DM, OM, and crude fiber (CF) were significant (P < .05), merely due to a larger difference found for the diet enriched with cellulose. In Exp. 2, the TD and ID evaluated with the marker method were significantly lower (except for the TD of CF) than with the direct method, mainly because Cr recovery was below 100%. Overall, the marker method seems to be superior because the TD means obtained from Cr ratios were closer to the TD obtained from intact pigs. In general, the SICV technique seems to be suitable for long-term digestibility studies to measure the TD and ID in the same pig fed low-or high-fiber diets.

Effect of lecithin on the apparent ileal and overall digestibility of crude fat and fatty acids in pigs.

Four barrows of approximately 40 kg initial body weight, fitted with post-valvular T-cecum cannulas, were used to study the effect of lecithin as an external emulsifier on apparent ileal and overall digestibility of crude fat, fatty acids, and other dietary nutrients (DM, N, GE, crude fiber [CF], P, Ca, and Mg), as well as the utilization of N, GE, Ca, P, and Mg. Two levels of lecithin (0 and .24%) and two levels of rendered fat (0 and 6%) in cereal-soybean meal-based diets were investigated according to a 4 x 4 Latin square design. No significant interactions were found between lecithin and rendered fat for apparent digestibility of crude fat as estimated at the end of the small intestine and the total digestive tract. Lecithin decreased the apparent ileal digestibility of C16:0 fatty acid (P < .1) and the apparent overall digestibility of C14:0 fatty acid (P < .05) and C18:2 fatty acid (P < .1). The apparent ileal and overall digestibility of crude fat (P < .001) and total fatty acids (P < .05) increased with the inclusion of rendered fat in diets. Furthermore, rendered fat increased the apparent ileal and overall digestibility of C14:0 (P < .01), C16:1 (ileal, P < .001; overall, P < .1), and C18:1 (P < .05) fatty acids and the apparent overall digestibility of C18:0 (P < .001) fatty acid. Lecithin had no impact on the apparent digestibility and retention (percentage of intake) of GE, N, total P, Ca, and Mg.(ABSTRACT TRUNCATED AT 250 WORDS)

Apparent digestibility and retention of nutrients bound to phytate complexes as influenced by microbial phytase and feeding regimen in pigs.

Five barrows of approximately 45 kg BW, fitted with post-valvular T-cecum cannulas at the ileo-cecal junction, were assigned randomly to five treatments (5 x 5 Latin square design) to assess the effect of microbial phytase and feeding regimen (frequency and level) on the apparent digestibilities (total tract [ATTD] and ileal [AID]) and retention of nutrients. A corn-tapioca-soybean meal diet of low intrinsic phytase activity, containing no added inorganic P, was fed either without or with microbial phytase from Aspergillus niger var. Van Tieghem (800 phytase units/kg of diet) at different feeding frequencies (once, twice, or seven times per day) and feeding levels (2.3 vs 2.8 times the maintenance requirement for ME, i.e., 418 kJ ME/BW.75). Microbial phytase enhanced significantly the ATTD of DM, OM, CP, Ca, total P, and amino acids (except for cystine and proline). Also, the AID of total P, phytic acid, methionine, and arginine was increased (P < .05 or .01). As a consequence of adding this enzyme, the retention (grams/day) of N, Ca, and P was greater (P < .01) and their daily excretion was diminished by 5.5, 2.2, and 1.9 g/d, respectively. The feeding level exerted a minor effect on the ATTD and AID (except for methionine and cystine), although the retention (grams/day) of N, Ca, and P was greater (P < .01) at the higher level of feeding. The feeding frequency influenced significantly the ATTD of Ca, tryptophan, and isoleucine and the AID of phytic acid, cystine, arginine, isoleucine, and phenylalanine. Also, N retention (grams/day) was reduced in pigs fed once daily (P < .01).

The effect of supplementary Aspergillus niger phytase in diets for pigs on concentration and apparent digestibility of dry matter, total phosphorus, and phytic acid in different sections of the alimentary tract.

Six barrows of approximately 37 kg BW, fitted with two simple T-cannulas in the duodenum (25 cm posterior to the pylorus) and terminal ileum (12 to 15 cm anterior to the ileocecal junction), were fed two diets containing 2.1 g of P/kg in the form of phytic acid and a low intrinsic phytase activity (corn-soybean meal based diet [Diet A] or a typical Dutch diet [Diet B]) without or with supplementary microbial phytase from Aspergillus niger (var. ficuum) equal to 1,500 phytase units per kilogram of diet, in a crossover design. The apparent duodenal, ileal, and total tract (overall) digestibilities of DM, total P, and phytate P (phytic acid x .282) were calculated using both Cr-NDR (neutral detergent residue mordanted with Cr) and Co-EDTA as dual-phase markers. Concentration of total P in the ileal digesta (P less than .01) and feces (P less than .001) of pigs fed microbial phytase was lower than without this enzyme, irrespective of the diet. Ileal digestibility of total P was 18.5 and 29.8 percentage units higher (which was a 1.7- to 2.9-fold increase) due to added Aspergillus niger phytase (P less than .05). Also, total tract (overall) digestibility increased by 27.0 to 29.7 percentage units (P less than .01). Phytic acid concentration in the duodenal and ileal digesta of pigs receiving microbial phytase was lower (P less than .01 or .001), resulting in its higher ileal digestibility (dephosphorylation rate) by 50.1 percentage units for Diet A and by 75.4 percentage units for Diet B. Irrespective of the treatment, no phytase activity could be detected in the ileal digesta of pigs.