Effect of feed intake level on ileal digestibilities of crude protein and amino acids in diets for piglets

BACKGROUND: The study was conducted to determine the effect of graded levels of feed intake on apparent (AID) and standardized (SID) ileal digestibilities of crude protein (CP) and amino acids (AA) in diets for piglets. The piglets were surgically fitted with simple T‐cannulas at the distal ileum. The cornstarch–casein–soybean meal‐based diets were fed at three graded levels of feed intake corresponding to 30, 45 and 60 g kg^?1 body weight (BW) per day. RESULTS: The AID and SID of most AA were quadratically affected by the feed intake level (P?0.05). Initially, both AID and SID of most AA increased up to 1.9 percentage units as the feed intake level was increased from 30 to 45 g kg^?1 BW. Thereafter, these AID and SID values decreased by 2.6 and 2.7 percentage units, respectively, as the feed intake level was further increased from 45 to 60 g kg^?1 BW. CONCLUSION: Because the voluntary feed intake is highly variable in piglets after weaning, comparison of ileal AA digestibilities between and within studies may be confounded by variations in feed intake level. Thus, when designing digestibility studies with piglets, a standardization of feed intake should be taken into consideration. Copyright © 2011 Society of Chemical Industry     

The effect of food dry matter intake on endogenous ileal amino acid excretion determined under peptide alimentation in the 50 kg liveweight pig

The daily ileal excretion of amino acids was measured at different food dry matter intakes for the 50 kg liveweight pig under conditions of peptide alimentation. The experiment comprised two cross-over design trials each involving four pairs of entire male pigs fitted with simple T-cannulae at the terminal ileum and fed a hydrolysed casein semi-synthetic diet. Each pair of pigs received one of four sequences of food dry matter intake arranged in a Latin square design, namely 0.06, 0.08, 0.10 and 0.12 (Trial 1) and 0.05, 0.07, 0.09 and 0.11 (Trial 2) of metabolic body weight (W^0.75) day^?1. Each pig received the diet at its described level of intake for 8 days, with continuous 24 h collection of ileal digesta on the fifth and eighth days. Chromic oxide was included in the diet to permit correction of ileal flows to complete digesta collection. Pooled digesta from each pig at each level of dry matter intake were centrifuged and ultrafiltered and the high-molecular-weight fraction was analysed for amino acid and nitrogen contents. There were significant (P < 0.05) linear relationships between endogenous ileal amino acid, nitrogen and dry matter excretion (mg day^?1) and food dry matter intake (g day^?1) except for lysine, glutamic acid and phenylalanine which increased in a curvilinear manner (P < 0.05). The results indicate that dietary dry matter intake influences endogenous excretion from the ileum. The relationships, determined under physiological conditions, provide preliminary data on the magnitude of small intestinal amino acid loss in the young growing pig.     

Evaluation of barley and triticale as feed ingredients in growing Iberian pigs: amino acid and carbohydrate ileal digestibility

BACKGROUND: Iberian pig production is linked to the use of the Mediterranean woodland, where the use of local feed resources is of paramount importance for the sustainability of the system. The aim of the present work was to explore the potential of triticale cv. Camarma as compared to barley cv. Esgueva in Iberian pig feeding by studying their respective ileal digestibilities of amino acids and carbohydrates in animals cannulated at the end of the ileum. RESULTS: Leu, Met and Tyr had (P < 0.05) greater standardised ileal digestibilities (SID) in pigs fed triticale diet. There was a trend (P = 0.07) towards greater SID of Thr in pigs fed the barley diet. The least digestible indispensable amino acids were Ile (74.6% SID) for barley and Thr (78.9% SID) for triticale. Except for β‐glucans, apparent ileal digestibilities (AIDs) of individual non‐starch polysaccharide (NSP), sugars and starch were greater in pigs fed triticale (P < 0.05). Nevertheless, total amounts of NSP digested were greater in pigs fed the barley diet (P < 0.05). CONCLUSION: Overall, triticale cv. Camarma had greater amino acid and carbohydrate AID than barley cv. Esgueva and may represent a valuable grain for Iberian pig feeding. Copyright © 2008 Society of Chemical Industry     

Endogenous lysine in ileal digesta in the growing rat determined using different methods

BACKGROUND: Endogenous lysine in ileal digesta has been determined directly using highly digestible proteins and hydrolysates and assuming a complete absorption of dietary amino acids. In this study, the endogenous lysine in the ileal digesta of rats fed casein was determined using the guanidination method (baseline) and directly (assuming complete digestion and absorption) for casein and a highly hydrolysed casein. The peptide alimentation/ultrafiltration technique was also used to determine the endogenous ileal lysine for the casein hydrolysate (Peptopro®). RESULTS: Mean endogenous ileal lysine for rats given the unguanidinated casein and determined directly assuming complete digestion and absorption (644 mg kg^?1 dry matter intake (DMI)) or for a highly hydrolysed casein with the same assumption (596 mg kg^?1 DMI) was significantly (P < 0.05) higher than the endogenous ileal lysine for casein determined using the guanidination method (274 mg kg^?1 DMI). The endogenous lysine in ileal digesta for a casein hydrolysate determined using the alimentation/ultrafiltration method (302 mg kg^?1 DMI) was not significantly (P < 0.05) different from that based on the guanidination method but was significantly (P < 0.05) lower than the equivalent endogenous lysine determined directly. CONCLUSION: Dietary amino acids are not completely absorbed from casein or its hydrolysate and determining endogenous amino acids in ileal digesta directly, assuming complete absorption, overestimates the amount of endogenous ileal amino acids. Copyright © 2009 Society of Chemical Industry     

Effect of condensed tannin in cottonseed hulls on endogenous ileal amino acid loss in the growing rat

The effect of condensed tannin (CT) in cottonseed hulls (CSH) on endogenous ileal amino acid flow in the growing rat was evaluated. CSH contain around 900 g kg^?1 fibre and 52 g kg^?1 total CT. Twenty-four rats were allocated to four semi-synthetic diets, which contained enzymically hydrolysed casein (EHC) as the sole source of dietary nitrogen and chromic oxide as an indigestible marker. Two of the diets contained no CSH while the remaining two contained 50 g kg^?1 CSH. At each level of hull inclusion (0 and 50 g kg^?1), polyethylene glycol (PEG: MW 3500) was added (6 g kg^?1) to one of the diets. The effect of CT was assessed by determining endogenous ileal amino acid loss in the presence or absence of PEG, which binds and inactivates CT. The rats were given their respective experimental diets ad libitum for 14 days. Samples of digesta were collected at slaughter from the terminal 15 cm of ileum. The digesta samples were centrifuged and the supernate ultrafiltered. The precipitate plus retentate (MW > 10000) fraction affords an estimate of endogenous loss. Inclusion of CSH in the EHC based diet increased ileal flow of total nitrogen (1387 versus 1623 μgg^?1 dry matter intake; P ≤ 0.05), increased ileal flow of total amino acids (23%; P ≤ 0.01), and significantly increased ileal flow of several individual amino acids. There was no significant effect of PEG and no PEG × diet interaction; showing that the CSH effects could not be explained by action of CT. The presence of hulls in commercial cottonseed meal would appear to contribute to the reported low apparent ileal amino acid digestibility coefficients for cottonseed meal by increasing endogenous ileal amino acid flow, but this effect is not due to the CT component of the hulls.     

Ileal digestibility of defatted soybean,lupin and chickpea seed meals in cannulated Iberian pigs: I. Proteins

Five castrated male Iberian pigs (100 ± 2 kg body weight) fitted with T‐shaped cannulas at the terminal ileum were used to determine ileal digestibility of legume seed meals. The diets were based on defatted soybean, lupin or chickpea seed meals and contained similar levels of digestible energy (14.2–15.1 kJ g^?1) and protein (107 g kg^?1). Protein‐free and a hydrolysed casein diets were used to study endogenous ileal amino acid flows. Chromium oxide (10 g kg^?1 diet) was added to the diets as an indigestible marker. Ileal flows in pigs fed the hydrolysed casein diet were different (p < 0.05) in amino acid contents and composition from those on the protein‐free diet. Ileal sialic acid flows in pigs fed lupin‐ or chickpea‐based diets were higher (p < 0.05) than those of animals fed soybean or casein diets. Among essential amino acids, only the apparent ileal digestibilities of phenylalanine and valine in lupin meal were lower (p < 0.05) than those in soybean. Apparent ileal digestibilities of lupin aspartate and proline, together with chickpea aspartate, were also lower (p < 0.05) than those of soybean. True ileal digestibility of nitrogen in pigs fed lupin or chickpea meals, calculated according to values from animals fed the protein‐free diet, was lower (p < 0.05) than that for soybean or casein. Among individual essential amino acids, only the true ileal digestibility of phenylalanine in lupin was lower (p < 0.05) than that in soybean. True ileal digestibility of nitrogen calculated according to values obtained with pigs fed a hydrolysed casein diet was not different among soybean, lupin or chickpea meals. Among essential amino acids, only the true ileal digestibilities of isoleucine and lysine in chickpea were lower (p < 0.05) than those of soybean. It is concluded that true ileal nitrogen and amino acid digestibilities of lupin and chickpea meals are comparable to those of defatted soybean in Iberian pigs. The results with protein‐free diets tended to underestimate endogenous protein secretion in pigs fed on diets containing protein. Copyright © 2005 Society of Chemical Industry     

Determination of True Ileal Amino Acid Digestibility in Feedstuffs for Pigs with the Linear Relationships between Distal Ileal Outputs and Dietary Inputs of Amino Acids

This study was carried out to investigate the methodological aspects of extrapolating the ileal losses of endogenous amino acids (AA) with linear relationships between the distal ileal outputs and dietary inputs of AA. Six barrows, average initial body weight 35 kg, were fitted with a simple T-cannula at the distal ileum and fed six diets according to a 6×6 Latin square design. Six maize starch-based diets containing six levels of crude protein (CP) and AA from soya bean meal (4, 8, 12, 16, 20 and 24% CP, respectively) were formulated. Chromic oxide (4 g kg^-1 diet) was included as the digestibility marker. Each experimental period consisted of 8 days. Ileal digesta were collected, at 2 h intervals, for a total of 24 h during days 7 and 8. There were strong linear relationships (P<0·01) between the ileal outputs and dietary inputs of AA. Differences in ranges of graded dietary levels of AA affected the linearity and caused large differences in the extrapolated levels of ileal endogenous AA. Therefore, the design of a suitable range of graded dietary levels of AA is the most important methodological consideration for the determination of endogenous AA losses and the true ileal digestibility values of AA with the linear relationship. For CP and the essential AA, the true ileal digestibility values (%) in soya bean meal and the ileal endogenous losses (g kg^-1 dry matter intake, in parentheses) were as follows: CP, 89·4 (16·4); arginine, 96·1 (0·68); histidine, 92·4 (0·24); isoleucine, 91·7 (0·45); leucine, 90·7 (0·69); lysine, 90·5 (0·48); methionine, 93·6 (0·13); phenyl-alanine, 92·5 (0·38); threonine, 86·5 (0·71) and valine, 90·3 (0·56). Furthermore, the levels of endogenous AA extrapolated with the linear relationships between the ileal outputs and dietary inputs of AA were very close to the values estimated with the linear relationships between the dietary contents of apparent ileal digestible and total AA, suggesting that both models of linear relationships can be used as the regression analysis technique for determination of ileal losses of endogenous AA and true ileal digestibility values of AA in feedstuffs for pigs. © 1997 SCI.     

Ileal digestibility of defatted soybean,lupin and chickpea seed meals in cannulated Iberian pigs: II. Fatty acids and carbohydrates

Five castrated male Iberian pigs (100 ± 2 kg mean live body weight) fitted with T‐shaped ileal cannulas were used to determine ileal digestibility of legume seed meals. The diets were based on defatted soybean (256 g kg^?1), lupin (451 g kg^?1) or chickpea (731 g kg^?1) seed meals and contained similar amounts of digestible energy (14.2–15.1 kJ g^?1) and protein (107 g kg^?1). Only myristic acid (C14:0) ileal apparent digestibility was higher (p < 0.05) in lupin than in chickpea meal. Ileal apparent digestibility of unsaturated fatty acids (FA) (710–920 g kg^?1) was higher (p < 0.05) than that of saturated (480–710 g kg^?1) FA for both seed meals. Ileal digestibility of chickpea starch was 850 g kg^?1. Ileal digestibility of oligosaccharides (sucrose, raffinose, stachyose, verbascose and ciceritol) in lupin (820 g kg^?1) and chickpea (690 g kg^?1) was higher (p < 0.05) than that of defatted soybean (510 g kg^?1). However, total amounts of oligosaccharides digested were higher (p < 0.05) for lupin and chickpea meals (29.6 and 24.6 g kg^?1 feed respectively) than for soybean (15.2 g kg^?1 feed). Among individual non‐starch polysaccharide (NSP) sugars, ileal digestibility values for rhamnose and xylose in lupins were higher (p < 0.05) than those for soybean or chickpea. Ileal digestibility of lupin meal NSP (650 g kg^?1) was higher (p < 0.05) than those of soybean (560 g kg^?1) or chickpea (430 g kg^?1). Up to the terminal ileum, higher (p < 0.05) amounts of lupin total NSP (94.1 g kg^?1) than for soybean (24.3 g kg^?1) or chickpea (27.1 g kg^?1) were digested. Lactate, acetate and isobutyrate concentrations were higher (p < 0.05) in ileal contents of pigs fed lupin and chickpea seed meals compared with soybean‐fed animals. It is concluded that higher lactate and short chain fatty acids concentrations in ileal contents of pigs fed lupin or chickpea seed meals compared with soybean are likely to be the result of higher total amounts of lupin NSP and/or lupin and chickpea oligosaccharides digested up to the terminal ileum. This might have a protective effect on Iberian pig's intestinal physiology. Both lupin and chickpea meals are likely to constitute a valuable alternative to defatted soybean in Iberian pig feeding. Copyright © 2005 Society of Chemical Industry     

Effect of the duration of feeding of a protein‐free diet on endogenous ileal nitrogen and amino acid loss in the growing pig

The aim of the study was to determine whether endogenous nitrogen and amino acid excretions at the terminal ileum change over time in the growing pig fed a protein‐free diet for 8 days. Seven entire male pigs with an overall mean live weight of 81.6 kg (SEM 3.3 kg) and surgically implanted post‐valve T caecum cannulas were fed a semi‐synthetic casein‐based diet for 8 days. Food was withheld from the pigs for 24 h, after which they were fed a protein‐free diet for a further 8 days at a rate of 10% of metabolic body weight per day. Chromic oxide was included in the protein‐free diet as an indigestible marker. Ileal digesta were collected continuously from 13:00 to 18:00 h on each day of the experimental period. Endogenous ileal nitrogen flows were determined for each pig each day the protein‐free diet was given, and endogenous ileal amino acid flows for the first and eighth days. There were no significant (P > 0.05) effects of the duration of feeding of the protein‐free diet on endogenous ileal total nitrogen or amino acid flows, except for the amino acids glycine and cysteine, the flows of which significantly decreased over the 8 day period (P < 0.01 and P < 0.05 for glycine and cysteine respectively), from (mean ± SEM) 1639 ± 217 to 892 ± 212 µg g⁻¹ dry matter intake (DMI) for glycine and from 173 ± 13 to 127 ± 19 µg g⁻¹ DMI for cysteine. The relative contributions (moles of each amino acid as a proportion of total moles of amino acids) of threonine, glycine and cysteine decreased significantly (P < 0.05) and that of proline increased significantly (P < 0.05) during the 8 days that the protein‐free diet was fed to the pigs. © 2000 Society of Chemical Industry     

The diurnal pattern of ileal dry matter and endogenous ileal nitrogen flows in the growing pig

The aim was to examine the diurnal pattern of endogenous nitrogen flow at the terminal ileum of the pig. Seven entire male pigs with a mean body weight of 58 kg had post‐valve T‐caecum (PVTC) cannulae surgically implanted for the collection of ileal digesta. The pigs were fed equal‐sized meals (10% of metabolic body weight, W^0.75, per day) twice daily at 08:00 and 17:00. The semi‐synthetic diet included enzyme‐hydrolysed casein (<5000 Da, 100 g kg^?1 diet) as the sole source of nitrogen (N). The diet also contained chromic oxide (6 g kg^?1) as an indigestible marker. The pigs received the diet for an 8 day period, and digesta were continuously collected for 24 h periods (commencing at 08:00) on the fifth and eighth days. Digesta were analysed for dry matter (DM) and chromium (Cr), and endogenous N was determined in the precipitate + retentate fraction of the digesta following centrifugation and ultrafiltration (10 000 Da molecular weight cut‐off). The concentration of Cr expressed on a digesta DM basis and the ratio of endogenous N to Cr in the digesta were relatively constant over the 24 h digesta collection periods, with no statistically significant (P > 0.05) differences found for the latter measure in the digesta collected between 12:00 and 08:00. The endogenous N flow through the terminal ileum is the net effect of the secretion and reabsorption of endogenous N that occurs throughout the digestive tract. The net result of the latter two processes in the small intestine of the pig leads to a relatively constant endogenous N flow over time post‐feeding. © 2002 Society of Chemical Industry     

The apparent ileal digestibility of amino acids and the digestible energy content of naked oats (Avena sativa cv Bandicoot) fed to growing pigs

An experiment was conducted to determine the apparent ileal digestibility of amino acids and the digestible energy (DE) content of two samples of naked oats (Avena sativa cv Bandicoot) and to compare these parameters in wheat (Triticum aestivum cv Machete) and dehulled oats (groats; Avena sativa cv Echidna). Four Large White male pigs were fitted with simple T-piece ileal cannulae and allocated to experimental diets in a 4×4 Latin square design. Amino acid digestibility coefficients were determined after continuous eight hour collections of digesta over two consecutive days using acid-insoluble ash as an indigestible marker. Digestible energy was determined using grab samples of faeces. No significant difference between the four test cereals was found in the digestibility of all amino acids, except for proline and lysine. The apparent ileal digestibility of lysine in wheat (0·87) and two samples of naked oats (0·89 and 0·82, respectively) was lower (P<0·05) than dehulled oats (0·91). The mean DE value of the naked oats samples was 16·96 MJ kg⁻¹ (air-dry basis). The results suggest that Bandicoot naked oats and dehulled oats are superior amino acid and DE sources to wheat and have potential for use in weaner and grower pig diets. © 1998 SCI.     

Influence of lipase and/or emulsifier addition on the ileal and faecal nutrient digestibility in growing pigs fed diets containing 4% animal fat

Information on the addition of lipase and/or emulsifiers to less digestible or saturated fat sources, such as tallow or other animal fats, used in swine feeding is very limited. Therefore, in a 4 × 4 Latin square design, the effects of adding lipase (0.05% L5, microbial source) and/or an emulsifier (0.3% Lysoforte) on the apparent ileal (AID) and faecal (AFD) digestibility of the main nutrients and fatty acids in particular were studied with four ileal‐cannulated growing pigs (female, initial live weight 20 kg) fed diets containing barley/soybean meal supplemented with 4% animal fat. The fat source contained 35% saturated (S) and 65% unsaturated (U) fatty acids. All diets were free of antibacterial substances (antibiotics, copper sulphate or zinc oxide beyond requirements), in order to avoid interactions between the parameters studied and the gut flora. Lipase addition did not affect the AID or AFD of fat. However, the digestibility of minor fatty acids (C6:0, C14:0) was significantly improved by lipase at both ileal and faecal level. On the other hand, lipase supplementation (P < 0.05) improved the AID of dry matter (DM) and energy as well as the AFD of DM, organic matter (OM), crude protein (CP), ash and energy. Addition of an emulsifier did not have any significant influence on the AID or AFD of fat, while the AID values of DM, OM, CP and energy as well as the AFD values of DM, OM, CP and ash were significantly (P < 0.05) improved. Adding lipase in combination with an emulsifier to the diets decreased (P < 0.05) the AID and AFD of fat, with minor effects on the AID and AFD of the non‐fat components of the diet. The lack of improvement in the digestion of fat by exogenous lipase and/or emulsifier may be related to the rather high U/S ratio (0.65:0.35) of the animal fat source used and to the mode of incorporation of the emulsifier (no pre‐dispersion in the fat source). Furthermore, during the trial the diets, stored at room temperature, showed a steady increase in their content of free fatty acids (to more than 700 g kg^?1 fat), due to endogenous lipase activity, leaving less room for upgrading the digestion of animal fat by exogenous lipase and/or emulsifier. Copyright © 2004 Society of Chemical Industry     

Dietary fibre level and enzyme inclusion affect nutrient digestibility and excreta characteristics in grower pigs

An experiment was conducted with 12 grower pigs to determine the effects of (1) manipulating dietary neutral detergent fibre (NDF) level and (2) dietary inclusion of fibre‐degrading enzymes on nutrient digestibility and excreta characteristics in pigs. Four diets were formulated to contain three levels of NDF: 1, 66 g kg^?1 NDF (low fibre); 2, 121 g kg^?1 NDF (moderate fibre); 3, 222 g kg^?1 NDF (high fibre); 4, diet 3 plus 2.0 g kg^?1 enzyme. Increasing levels of dietary NDF linearly decreased dry matter and energy digestibilities (r² = 0.99, P < 0.05). Lowering dietary NDF from 222 to 121 g kg^?1 improved nitrogen digestibility by 13% (P < 0.01). Faecal production was decreased by 9% for each 1% decrease in dietary NDF content (r² = 0.99, P < 0.05). Inclusion of fibre‐degrading enzymes in the high‐fibre diet improved dry matter and energy digestibilities by 2 and 3% respectively, and reduced faecal production by 10% (P < 0.01). Faecal and manure (faeces plus urine) pH values from pigs fed the high‐fibre diet and the high‐fibre plus enzyme diet were lower than those from pigs fed the other experimental diets (P < 0.05). In conclusion, lowering the dietary NDF level or inclusion of fibre‐degrading enzymes in high‐fibre diets may offer relatively practical and easy methods for reducing waste production in pigs. © 2002 Society of Chemical Industry     

Nutrient utilisation in response to dietary supplementation of chicory inulin in growing pigs

The digestive and post‐absorptive utilisation of dietary crude protein (CP), calcium (Ca) and phosphorus (P) in response to dietary supplementation of chicory inulin extract was investigated with six Yorkshire barrows with an average initial body weight of 30 kg. The barrows were fed a corn (maize) and soybean meal‐based diet containing 0 or 50 g kg^?1 chicory inulin extract according to a two‐period crossover design. The digestive utilisation of CP, Ca and P did not differ (P > 0.05) between the control and the inulin‐fed pigs. Furthermore, the post‐absorptive urinary loss of CP and Ca was not affected (P > 0.05) by 50 g kg^?1 chicory inulin supplementation. However, inulin supplementation improved post‐absorptive P utilisation through a reduction (P = 0.01) in urinary P loss by 1.6 percentage units compared with the control group. In conclusion, dietary supplementation of 50 g kg^?1 chicory inulin does not affect dietary CP and Ca utilisation but does reduce urinary P loss in growing pigs. Copyright © 2004 Society of Chemical Industry     

Pot evaluation of synthetic nanosiderite for the prevention of iron chlorosis

BACKGROUND: Iron chlorosis is a problem that affects crops grown on calcareous soils. In this work, we assessed the effectiveness of nanosized siderite (FeCO₃) to prevent iron chlorosis, the underlying hypothesis being that the oxidation products of siderite in soil are poorly crystalline, and hence plant‐available, iron oxides. RESULTS: Nanosized siderite was prepared by mixing FeSO₄ and K₂CO₃ solutions, either pure or doped with phosphate (siderite SID and SIDP, respectively). The average specific surface area was ～140 m² g^?1 for SID and ～220 m² g^?1 for SIDP. Experimental oxidation in a calcite suspension yielded goethite for SID and a mixture of lepidocrocite and goethite for SIDP. Two pot experiments in which a SID or SIDP suspension was applied to a calcareous soil at a rate of ～2 g Fe kg^?1 showed nanosiderite to prevent iron chlorosis in chickpea. In a pot experiment with five successive crops, one initial application of ～0.7 g Fe kg^?1 soil in the form of SID or SIDP was as effective as FeEDDHA in preventing Fe chlorosis. The residual effect of nanosiderite when applied to the first crop alone clearly exceeded that of FeEDDHA. CONCLUSION: Nanosiderite suspensions applied at rates of ～0.7 g Fe kg^?1 soil were highly effective in preventing iron chlorosis and have a great residual effect. Copyright © 2012 Society of Chemical Industry     

Protein nutrition of dairy cows receiving grass silage diets. Effects on silage intake and milk production of postruminal supplements of casein or soya-protein isolate and the effects of intravenous infusions of a mixture of methionine,phenylalanine and tryptophan

Milk production responses to protein supplementation of grass silage diets were investigated in two experiments with dairy cows. In Experiment 1. four cows received a basal diet of grass silage ad libitum plus a barley/soya supplement at 5 kg day^?1. The cows received the following treatments in a 4 × 4 Latin square design with 10-day periods: (1) basal diet, (2) basal diet plus 230 g casein day^?1 infused into the abomasum; (3) basal diet plus 225 g soya protein isolate (SPI) day^?1 into the abomasum; and (4) basal diet plus a dietary addition of 1.2 kg fishmeal-based product (AP) day^?1. All three supplements increased (P < 0.05) the yield of milk and milk protein relative to the basal diet, the values being 16.9. 535:18.8. 610; 19.5, 625; and 18.5 kg day^?1 and 582 g day^?1 for the basal. AP, casein and SPI treatments respectively. Responses to casein were greater (P < 0.05) than to SPI. Changes in the concentrations of amino acids in blood plasma suggested that methionine, tryptophan and phenylalanine were in shortest supply relative to demand, and their potential role as limiting amino acids was investigated in a second experiment. In Experiment 2, four dairy cows were used in a 4 × 4 Latin square design with 10-day periods. The four treatments were (1) a diet of grass silage ad libitum plus 5 kg day^?1 of a barley/soya supplement containing 176 g CP kg^?1 DM (LP); (2) LP plus an intravenous infusion of 5.0 g methionine, 9.1 g phenylalanine and 2.2 g tryptophan day^?1; (3) grass silage ad libitum plus 5 kg day^?1 of a barley/soya supplement containing 334 g CP kg^?1 DM (HP); and (4) HP plus the intravenous infusion of methionine, phenylalanine and tryptophan. The HP treatment produced a higher yield (P < 0.05) of milk protein than the LP treatment (722 vs. 667 g day^?1) but the amino acid infusion had no effect with either treatment. The elimination of methionine, phenylalanine and tryptophan (and, in previous experiments, methionine and lysine) as candidates for limiting amino acids on diets of grass silage plus soya-based supplements questions whether the differences in responses to casein and SPI can be explained in terms of their amino acid compositions. The role of factors such as peplides, producing during digestion, some of which may be biologically active, deserves investigation.     

The effect of food dry matter intake on the flow of amino acids at the terminal ileum for rats fed an enzyme‐hydrolysed casein‐based diet

The aim of the study was to determine whether food dry matter intake had an effect on endogenous ileal amino acid flows in the rat when the flows were expressed in units of mg g^?1 dry matter. Eighty 200 g body weight rats were trained for 7 days to consume a casein‐based diet over a daily 3 h feeding period, and then an enzyme‐hydrolysed casein (MW < 5000 Da)‐based diet, with chromic oxide as an indigestible marker, was fed for a further 8 days. The mean ratio of food intake to metabolic body weight over all 80 rats was determined on days 11 and 12. On day 15, food was offered to groups of 10 rats at each of eight intake levels. The intake levels were calculated from the mean food intake value and individual metabolic body weights and scaled in increments of 0.1 by factors ranging from 0.3 to 1.0. Digesta were collected from the terminal ileum 3 h after the start of the meal, and endogenous ileal amino acid flows were determined after amino acid and Cr analyses of the diet and endogenous ileal digesta fractions prepared by centrifugation and ultrafiltration (10 000 Da molecular weight cut‐off). The linear regression relationships between ileal amino acid flows, expressed as mg g^?1 dry matter, and dry matter intakes demonstrated that all slopes were negative but that the slopes for nine of these amino acids were not significantly different from zero (P > 0.05). There were significant slopes (P < 0.05) for the other eight amino acids, although the magnitudes of the effect were small. When the data were re‐examined after removing the lowest feeding level, the slopes for most of these amino acids were no longer statistically significant. The results showed that the measures of amino acid flow (mg g^?1 dry matter), except for isoleucine and cystine, over a wide range of food intakes were not materially affected by food intake. From the perspective of bioassay logistics the results indicate that expressing ileal amino acid flows proportional to dry matter intake is justified over the range of intakes found in practice for determining true ileal amino acid digestibility by the enzyme‐hydrolysed casein method. © 2002 Society of Chemical Industry     

Effect of extrusion on in situ ruminal protein degradability and in vitro digestibility of undegraded protein from different feedstuffs

BACKGROUND: The effect of extruding maize, barley, whole soybean (WSB), peas, lupins and soybean meal (SBM) on their in situ ruminal protein degradability and in vitro digestibility of the rumen undegraded protein (RUP) was studied. Two mixtures containing 0.75 WSB or lupins and 0.25 maize were also formulated. RESULTS: Extrusion of maize resulted in an increase of its effective protein degradability from 0.538 to 0.734 (P < 0.001), whereas the opposite occurred with barley (from 0.854 to 0.797; P < 0.001). Extrusion increased the in vitro digestibility of the RUP of both cereals, increasing therefore the amount of barley crude protein (CP) digested in the intestines (PDI) from 62 to 176 g kg^?1 CP (P < 0.01), whereas maize resulted in lower (332 versus 229 g kg^?1 CP; P < 0.01). Extrusion decreased (P < 0.001) the protein degradability of the three legume seeds and increased (P < 0.001) the in vitro digestibility of the RUP, resulting in a PDI increase (P < 0.001), from 60 to 367 g kg^?1 CP for peas, from 69 to 265 g kg^?1 CP for WSB and from 107 to 205 g kg^?1 CP for lupins. This effect was enhanced when WSB was extruded jointly with maize. The extrusion of SBM also resulted in an increase in the PDI from 296 to 384 g kg^?1 CP (P < 0.001). CONCLUSION: Extrusion decreases the rumen protein degradability of legume seeds, soybean meal and barley, and increases the digestibility of the RUP, resulting in an increase in the feed protein digested in intestine. The extrusion of soybean seeds together with maize enhances these effects. Copyright © 2008 Society of Chemical Industry     

Amino acid and energy digestibility in peas (pisum sativum) from white-flowered spring cultivars for growing pigs

Six barrows, average initial weight 35 kg, fitted with a simple T-cannula at the distal ileum, were used to determine the apparent ileal digestibilities of amino acids (AA) and the digestibility of energy in six diets according to a 6 x 6 Latin square design. The pigs were fed six corn starch-based diets formulated to contain 165 g CP per kg from six different white-flowered spring pea cultivars. Chromic oxide was used as the digestibility marker. The pigs were fed twice daily, at 08:00 and 20:00 h. Each experimental period lasted 9 days. Faeces were collected from 08:00 on day 6 to 08:00 h on day 8; ileal digesta from 08:00 on day 7 to 08:00 h on day 9. Of the indispensable (+semi-) AA, there were differences (P≤0.05) in the AA digestibilities of arginine, methionine, phenylalanine and tyrosine between the cultivars. In the same order for these AA, the digestibilities ranged from 81.3 to 89.0%, 67.8 to 75.1%, 68.0 to 74.6% and 66.1 to 74.8%, respectively. Within each cultivar, the digestibilities of cysteine and threonine were relatively low, ranging from 58.5 to 65.9% and from 59.6 to 67.4%, respectively. The digestibility of lysine was relatively high, ranging from 80.3 to 84.0%. The energy digestibilities in the pea cultivars ranged from 87.4 to 90.2% (P≤0.05); the digestible energy content from 14.0 to 14.4 MJ kg^-1 DM. There was considerable disappearance of energy in the large intestine, ranging from 4.4 to 6.2 MJ kg^-1 DM intake from peas. In conclusion, when measured with the ileal analysis method, there were differences (P≤0.05) in the digestibilities of some of the indispensable AA between the pea samples. Furthermore, the relatively low digestibilities of methionine and cysteine further accentuate the limitation of the sulphur-containing AA in protein from peas.     

Effect of phytase inclusion and calcium/phosphorus ratio on the performance and nutrient retention of grower–finisher pigs fed barley/wheat/soya bean meal‐based diets

Two experiments were conducted to evaluate the effects of phosphorus (P) level and calcium (Ca)/total P (tP) ratio on the efficacy of microbial phytase. Experiment 1 examined the effects of P concentration and microbial phytase inclusion on mineral excretion and pig performance, while experiment 2 examined the effects of Ca/tP ratio and microbial phytase inclusion on mineral excretion and pig performance. In experiment 1, nutrient and mineral digestibility (n = 4) and growth performance (n = 12) were determined in pigs individually fed diets containing (T1) 5.5 g kg^?1 tP, 2.3 g kg^?1 available P (aP) and 8.0 g kg^?1 Ca, (T2) 5.5 g kg^?1 tP, 2.3 g kg^?1 aP, 8.0 g kg^?1 Ca and 750 FYT kg^?1 Peniophora lycii phytase, (T3) 4.3 g kg^?1 tP, 1.4 g kg^?1 aP and 8.0 g kg^?1 Ca and (T4) 4.3 g kg^?1 tP, 1.4 g kg^?1 aP, 8.0 g kg^?1 Ca and 750 FYT kg^?1 P lycii phytase. In experiment 2, nutrient and mineral digestibility (n = 4) and growth performance (n = 12) were determined in pigs individually fed diets containing (TT1) 4.3 g kg^?1 tP and 8.0 g kg^?1 Ca, (TT2) 4.3 g kg^?1 tP, 8.0 g kg^?1 Ca and 750 FYT kg^?1 P lycii phytase, (TT3) 4.3 g kg^?1 tP and 5.0 g kg^?1 Ca and (TT4) 4.3 g kg^?1 tP, 5.0 g kg^?1 Ca and 750 FYT kg^?1 P lycii phytase. All diets were formulated, using standard feeding values for the ingredients, to have similar concentrations of digestible energy (DE) and lysine. In experiment 1, pigs offered the low‐P diets had significantly lower P intake (P < 0.001), faecal P excretion (P < 0.05), Ca intake (P < 0.05) and faecal Ca excretion (P < 0.05) compared with pigs given the adequate‐P diets. These pigs also had significantly lower daily gain (P < 0.01), feed intake (P < 0.05) and feed conversion ratio (FCR) (P < 0.05). The inclusion of phytase in both the adequate‐ and low‐P diets increased the digestibility of energy (P < 0.05) and Ca (P < 0.01) but had no effect on pig performance. In experiment 2, lowering the Ca/tP ratio from 1.85:1 to 1.15:1 increased the DE content of the diet (P < 0.05). The inclusion of phytase increased (P < 0.05) the digestibility of protein (0.874 versus 0.840, SEM 0.009) and Ca (0.427 versus 0.380, SEM 0.019) as well as the DE content of the diet (14.47 versus 14.26 MJ kg^?1, SEM 0.073). There was a significant ratio × phytase interaction (P < 0.5) for P digestibility. Microbial phytase significantly increased P digestibility when added to the 1.15:1 ratio diet but had no effect when added to the 1.85:1 ratio diet. The inclusion of microbial phytase increased feed intake (2.16 versus 2.00 kg day^?1, SEM 0.05; P < 0.05) and weight gain (0.893 versus 0.818 kg day^?1, SEM 0.022; P < 0.05). Lowering the Ca/tP ratio resulted in a significant improvement in FCR (2.32 versus 2.40 kg kg^?1, SEM 0.03; P < 0.05). In conclusion, the beneficial effects of microbial phytase supplementation of pig diets are adversely affected by a wide Ca/tP ratio. © 2002 Society of Chemical Industry