Research note: Nutritive value of cold-pressed flaxseed meal for broiler chicken.

A study was conducted to evaluate standardized ileal digestibility (SID) of amino acids (AA) and N-corrected apparent metabolizable energy (AMEn) values of cold pressed flaxseed meal (CPFM) for broilers. One hundred and twenty broiler chicks were divided into 20 groups of 6 birds/group and fed 2 diets in a completely randomized design (10 groups/diet) from 14 to 21 d of age. The diets were cornstarch-based containing CPFM or conventional soybean meal (SBM; reference feedstuff) as the sole protein source. A N-free diet fed in another study conducted in the same facility and at the same time that the current study was conducted was used to estimate basal endogenous AA losses, and to calculate gross energy retention by difference method. The CPFM had greater neutral detergent fiber and ether extract contents (21.40 vs. 8.18% and 20.4 vs. 2.47% as is, respectively), but lower CP (20.47 vs. 48.28% as is) than SBM. The SID values of all indispensable AA (except for Leu, Phe and Trp) for CPFM were lower (P < 0.05) than those for SBM. The apparent retention of gross energy (65.95 vs. 44.24%) and N (55.53 vs. 9.79%), and AMEn (2,699 vs. 2,491 kcal/kg) for CPFM were lower (P < 0.05) than those for SBM. In conclusion, CPFM can serve as alternative oilseed co-product feedstuff for poultry. However, the CPFM has lower SID of AA and AMEn values than SBM likely due to the greater fiber content in the former than in the latter.

Determination of the Optimal Level of Dietary Zinc for Newly Weaned Pigs: A Dose-Response Study.

One hundred and eighty individually housed piglets with an initial body weight of 7.63 ± 0.98 kg (at 28 days of age) were fed a diet containing either 153, 493, 1022, 1601, 2052 or 2407 mg zinc/kg (added Zn as zinc oxide; ZnO) from day 0-21 post weaning to determine the optimal level of Zn for weaned piglets. Body weight, feed intake and faecal scores were recorded, and blood and faecal samples were collected. Dietary Zn content quadratically affected both feed intake and gain in the first two weeks, with an approximately 1400 mg Zn/kg diet and a Zn intake of 400 mg/day as the optimal levels. The relative risk of diarrhoea increased up to 60% at day 7 and 14 if serum Zn status dropped below the weaning level (767 µg/L), and maintain the weaning serum Zn status required approximately 1100 mg Zn/kg (166 mg Zn/day) during week 1. Blood markers of intestinal integrity (D-lactate and diamine oxidase) were unaffected by dietary Zn, and dietary Zn levels of 1022 and 1601 mg/kg did not affect the faecal numbers of total bacteria, Lactobacilli and E. Coli bacteria compared to 153 mg Zn/kg. These results indicate that the requirement for Zn in newly weaned piglets may be substantially higher than currently assumed.

Growth performance, bone mineralization, nutrient digestibility, and fecal microbial composition of multi-enzyme-supplemented low-nutrient diets for growing-finishing pigs.

A study evaluated the effects of adding multi-enzyme mixture to diets deficient in net energy (NE), standardized ileal digestible (SID) amino acids (AA), standardized total tract digestible (STTD) P, and Ca on growth performance, bone mineralization, nutrient digestibility, and fecal microbial composition of grow-finish pigs. A total of 300 pigs (initial body weight [BW] = 29.2 kg) were housed by sex and BW in 45 pens of 7 or 6 pigs and fed 5 diets in a randomized complete block design. Diets were positive control (PC), and negative control 1 (NC1) or negative control 2 (NC2) without or with multi-enzyme mixture. The multi-enzyme mixture supplied at least 1,800, 1,244, 6,600, and 1,000 units of xylanase, ß -glucanase, arabinofuranosidase, and phytase per kilogram of diet, respectively. The PC was adequate in all nutrients. The NC1 diet had lower content NE, SID AA, STTD P, and Ca than PC diet by about 7%, 7%, 32%, and 13%, respectively. The NC2 diet had lower NE, SID AA, STTD P, and Ca than PC diet by 7%, 7%, 50%, and 22%, respectively. The diets were fed in four phases based on BW: Phase 1: 29-45 kg, Phase 2: 45-70 kg, Phase 3: 70-90 kg, and Phase 4: 90-120 kg. Nutrient digestibility, bone mineralization, and fecal microbial composition were determined at the end of Phase 1. Pigs fed PC diet had greater (P < 0.05) overall G:F than those fed NC1 diet or NC2 diet. Multi-enzyme mixture increased (P < 0.05) overall G:F, but the G:F of the multi-enzyme mixture-supplemented diets did not reach (P < 0.05) that of PC diet. Multi-enzyme mixture tended to increase (P = 0.08) femur breaking strength. Multi-enzyme mixture increased (P < 0.05) the ATTD of GE for the NC2 diet, but unaffected the ATTD of GE for the NC1 diet. Multi-enzyme mixture decreased (P < 0.05) the relative abundance of the Cyanobacteria and increased (P < 0.05) relative abundance of Butyricicoccus in feces. Thus, the NE, SID AA, STTD P, and Ca could be lowered by about 7%, 7%, 49%, and 22%, respectively, in multi-enzyme mixture-supplemented diets without negative effects on bone mineralization of grow-finish pigs. However, multi-enzyme mixture supplementation may not fully restore G:F of the grow-finish pigs fed diets that have lower NE and SID AA contents than recommended by 7%. Since an increase in content of Butyricicoccus in intestine is associated with improved gut health, addition of the multi-enzyme mixture in diets for pigs can additionally improve their gut health.

A study evaluated the effects of supplementing a multi-enzyme mixture that contain fiber degrading enzymes and phytase on the growth performance, bone strength, and fecal microbial composition of grow-finish pigs fed corn-wheat-wheat bran-based diets. Five diets fed were a positive control (PC) diet, and two negative control (NC1 and NC2) diets without or with the multi-enzyme mixture. The PC diet was adequate in all nutrients and had greater available (net) energy and digestible amino content than NC1 diet or NC2 diet by 7%, and greater digestible P content than the NC1 diet (by 32%) and NC2 diet (by 50%). The diets were fed from 30 to 120 kg body weight. Feed efficiency for PC diet was greater than that for NC1 diet or NC2 diet. Multi-enzyme mixture improved feed efficiency, bone strength, and fecal concentration of beneficial micro-organisms (known as Butyricicoccus) for NC1 and NC2 diets. However, feed efficiency for the NC1 and NC2 diets did not reach that for the PC diet. Thus, multi-enzyme mixture can fully restore bone strength (but not feed efficiency) and improve health of grow-finish pigs fed corn-wheat-wheat bran-based diets in which available energy, amino acids, and P contents have been reduced by the afore-mentioned margins.

Growth performance and nutrient digestibility of growing and finishing pigs fed multienzyme-supplemented low-energy and -amino acid diets.

A study was conducted to determine the effects of supplementing corn-soybean meal-based diets with a multienzyme on growth performance, bone mineralization, apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients of growing pigs. A total of 276 pigs (body weight [BW] = 33.99 ± 4.3 kg) were housed by sex in 45 pens of 6 or 7 pigs and fed 5 diets (9 pens/diet) in a randomized complete block design. Diets were positive control (PC); and negative control 1 (NC1) or negative control 2 (NC2) without or with multienzyme. The multienzyme used supplied at least 1,800, 1,244, 6,600, and 1,000 units of xylanase, ß-glucanase, arabinofuranosidase, and phytase per kilogram of diet, respectively. The PC diet was adequate in all nutrients according to NRC recommendations and had greater digestible P content than NC1 or NC2 diet by 0.134 percentage points. The PC diet had greater net energy (NE) and standardized ileal digestible amino acids (AA) content than NC1 diet by 3%, and than NC2 diet by 5%. The diets were fed in 4 phases based on BW: Phase 1: 34-50 kg; Phase 2: 50-75 kg; Phase 3: 75-100 kg; and Phase 4: 100-120 kg. Nutrient digestibility and bone mineralization were determined at the end of Phase 1. Overall (34-120 kg BW), pigs fed the PC and NC1 diets did not differ in average daily gain (ADG) and average daily feed intake. Pigs fed NC2 diet had lower (P < 0.05) ADG and gain-to-feed ratio (G:F) than those fed PC diet. Pigs fed PC diet had greater (P < 0.05) bone ash content and ATTD of P than those fed NC1 diet. The ATTD of GE for PC diet was greater (P < 0.05) than that for NC2 diet, and tended to be greater (P < 0.10) than that for NC1 diet. Multienzyme interacted (P < 0.05) with negative control diet type on overall ADG and AID of GE such that multienzyme did not affect overall ADG and AID of GE for the NC1 diet, but increased (P < 0.05) overall ADG and AID of GE for NC2 diet by 5.09 and 8.74%, respectively. Multienzyme did not interact with negative control diet type on overall G:F, bone ash content, AID of AA, and ATTD of nutrients. Multienzyme increased (P < 0.05) overall G:F, AID of methionine, ATTD of GE and P, and tended to increase (P = 0.056) bone ash content. The ADG, bone ash content, and ATTD of GE and P for the multienzyme-supplemented diets were similar to (P > 0.10) PC diet. Thus, NE and digestible AA and P can be lowered by ≤5% in multienzyme-supplemented diets without effects on growth performance and bone ash of pigs.

Toxicity of canola-derived glucosinolates in pigs fed resistant starch-based diets.

A study was conducted to determine effects of reducing hindgut pH through dietary inclusion of high-amylose cornstarch (HA-starch) on growth performance, organ weights relative to live body weight (BW), blood thyroid hormone levels, and glucosinolate degradation products of nursery pigs fed cold-pressed canola cake (CPCC). A total of 240 pigs (initial BW: 7.1 kg), which had been weaned at 21 d of age, were housed in 40 pens (6 pigs per pen) and fed 4 diets (10 pens per diet) in a randomized complete block design for 28 d. Four diets were a basal diet with CPCC at 0 or 40%, and with HA-starch at 0 or 40% in a 2 × 2 factorial arrangement. The diets were fed in two phases: Phase 1 from day 0 to 14 and Phase 2 from day 14 to 28 and were formulated to have the same net energy, standardized ileal digestible AA, Ca, and standardized total tract digestible P contents. Dietary inclusion of CPCC and HA-starch was achieved by a partial or complete replacement of corn, soybean meal, and soy protein. At the end of the study, one pig from each pen was euthanized to determine organ weights, blood parameters, hindgut pH, and glucosinolate degradation products. Dietary CPCC reduced (P < 0.05) overall average daily gain (ADG) by 15%; increased (P < 0.05) relative weights of liver and thyroid gland by 27% and 64%, respectively; and reduced (P < 0.05) serum tetraiodothyronine (T4) level from 30.3 to 17.8 ng/mL. Heart, kidney, and gastrointestinal tract weights; serum triiodothyronine level; and hindgut pH of pigs were unaffected by dietary CPCC. Dietary HA-starch reduced (P < 0.05) overall ADG, relative weight of thyroid gland, cecal, and colonic pH; but increased (P < 0.05) relative weight of colon; tended to increase (P = 0.062) serum T4 level. Dietary CPCC and HA-starch interacted (P = 0.024) on relative weight of thyroid gland such that dietary CPCC increased (P < 0.05) weight of thyroid gland for HA-starch-free diet (120 vs. 197 mg/kg of BW) but not for HA-starch-containing diet (104 vs. 130 mg/kg of BW). Dietary CPCC and HA-starch interacted (P = 0.001) on cecal isothiocyanate content such that dietary CPCC increased (P < 0.05) level of isothiocyanates for HA-starch-containing diet but not for HA-starch-free diet. In conclusion, dietary CPCC reduced growth performance, increased liver, size and interfered with thyroid gland functions of pigs. However, the negative effects of dietary CPCC on thyroid gland functions of nursery pigs were alleviated by dietary HA-starch.

Nutrient digestibility of soybean products in grower-finisher pigs1.

Solvent extraction of soybean creates soybean meal (SBM), but an array of other soybean products can be created using further processing of SBM or soybean. For accurate inclusion of these products in pig feed, characterization of digestible AA profile and energy value is required. Soybean products from processes such as extrusion (EX) of soybean and thermo-mechanical (TM) treatment, bioconversion using fermentation or enzymes (BC), and ethanol-water extraction (EW) of soybean meal were collected together with SBM. These 9 soybean products were tested in cornstarch-based diets together with an N-free diet for a total of 10 diets. Ten ileal-cannulated barrows (30.4 ± 0.7 kg initial BW) were fed 10 diets at 2.8 times maintenance DE for six 9-d periods with a 6 (periods) × 10 (pigs) Youden square. The control SBM contained 47.0% CP, 1.4% ether extract, and ADF 6.0%. The 9 soybean products contained 35.6% to 66.4% CP, 0.9% to 21.6% ether extract, and 4.4% to 8.0% ADF. The EW soybean products were high in CP (>61%), whereas the 2 EX soybean products were low in CP (<36%) but high in ether extract (≥19%). Chemically available Lys ranged from 92.6% to 100% of total Lys, indicating that minor Lys damage occurred during processing. The apparent total tract digestibility (ATTD) of energy was lower (P < 0.05) for soybean products with greater ether extract and ADF content than SBM, and varied among soybean products. The standardized ileal digestibility (SID) did not differ (P > 0.05) among soybean products for most AA, except for lower SID of Arg, Ile, Leu, Lys, Phe, and Tyr (P < 0.05) for EX2 and BC1 than other soybean products. The DE and predicted NE value did not differ (P > 0.05) among soybean products. The greater SID AA content (P < 0.05) in EW, BC, and TM1 soybean products than SBM was mainly a result of greater total AA content due to removal of other macronutrients. In conclusion, extrusion of soybean creates soybean products with a greater energy value but lower ATTD of energy and lower SID AA content than SBM. Further processing of SBM creates soybean products with greater CP and SID AA content but similar SID of AA than SBM. Thus, new technologies to process SBM or soybean create high-value ingredients to be included in pig diets, especially for young pigs with high nutritional requirements.

Nutrient digestibility of multi-enzyme supplemented low-energy and AA diets for grower pigs1.

A study was conducted to determine effects of supplementing multi-enzyme on apparent ileal digestibility (AID) of energy and AA; and apparent total tract digestibility (ATTD) of energy for pigs fed low-energy and AA diets. Eight ileal-cannulated barrows (initial BW: 38.7 ± 2.75 kg) were fed four diets in a replicated 4 × 4 Latin square design to give 8 replicates per diet. Diets were positive control (PC) diet, negative control (NC) diet without or with multi-enzyme at 0.5 or 1.0 g/kg. The PC diet was formulated to meet or exceed NRC (2012) nutrient recommendations for grower pigs (25 to 50 kg), except for Ca and digestible P, which were lower than NRC (2012) recommendations by 0.13 and 0.17 percentage points, respectively, due to phytase supplementation at 1,000 FTU/kg. The NC diet was formulated to be lower in NE by 75 kcal/kg and standardized ileal digestible AA content by a mean of 3%. These reductions were achieved by partial replacement of corn and soybean meal (SBM) and complete replacement of soybean oil and monocalcium phosphate in PC diet with 25% corn distillers dried grains with solubles (DDGS) and 3.6% soybean hulls. Multi-enzyme at 1.0 g/kg supplied 1,900 U of xylanase, 300 U of ß-glucanase, 1,300 U of cellulase, 11,500 U of amylase, 120 U of mannanase, 850 U of pectinase, 6,000 U of protease, and 700 U of invertase per kilogram of diet. The AID of GE, N, most AA, most component sugars of nonstarch polysaccharides (NSP) and P; ATTD of GE for PC diet was greater (P < 0.05) than those for NC diets. An increase in dietary level of multi-enzyme from 0 to 1.0 g/kg resulted in a linear increase (P < 0.05) in AID of Ile by 4.3%, and tended to linearly increase (P < 0.10) AID of Leu, Met, Phe, and Val by a mean of 3.4%. Increasing dietary multi-enzyme from 0 to 1.0 g/kg linearly increased (P < 0.05) AID of total NSP and P by 53.7% and 19.2%, respectively; ATTD of GE by 8.4% and DE and NE values by 8.8% and 8.2%, respectively; tended to linearly increase (P < 0.10) AID of GE by 8.1%. The NE values for NC diet with multi-enzyme at 1.0 g/kg tended to be greater (P < 0.10) than that for PC diet (2,337 vs. 2,222 kcal/kg of DM). In conclusion, multi-enzyme supplementation improved energy and nutrient digestibilities of a corn-SBM-corn DDGS-based diet, implying that the multi-enzyme fed in the current study can be used to enhance energy and nutrient utilization of low-energy AA diets for grower pigs.

Nutritive value of enzyme-supplemented carinata meal for growing pigs.

Carinata meal is increasingly available for livestock feeding. However, the effects of supplemental phytase and fiber degrading enzymes on nutritive value of carinata meal for pigs have not been reported. Objective of the study was to evaluate the standardized ileal digestibility (SID) of amino acid (AA), and digestible energy (DE) and net energy (NE) values of phytase- and fiber-degrading enzymes-supplemented carinata meal for growing pigs. Ten ileal-cannulated pigs (initial body weight = 53.9 ± 4.76 kg) were fed 4 diets in a replicated 4 × 4 Latin square design with two additional columns to give 10 replicates per diet. Diets included a corn-soybean meal (SBM)-based basal diet, basal diet with 25% carinata meal, basal diet with 25% carinata meal plus phytase at 2,000 FTU/kg and multi-carbohydrase at 0.2 g/kg, and in addition a nitrogen-free diet. The multicarbohydrase supplied 4 units of xylanase, 10 units of ß-glucanase, and 1,000 units of pectinase per kilogram of diet. The ratio of corn to SBM and soybean oil in carinata meal-containing diets was identical to that in the corn-SBM-based basal diet to allow calculation of AA and energy digestibility of carinata meal by the difference method. On a dry matter basis, carinata meal contained 50.2% crude protein, 0.88% ether extract, 15.37% acid detergent fiber, 1.82% Lys, 0.96% Met, 1.89% Thr, and 0.64% Trp, respectively. The SID of Lys, Met, Thr, and Trp for carinata meal were 51.4%, 82.2%, 65.9%, and 85.9%, respectively. The DE and NE values for carinata meal were 3,427 and 1,828 kcal/kg of dry matter, respectively. Supplementation of a combination of phytase and multicarbohydrase did not affect the apparent ileal digestibility of AA and SID of AA for the corn-SBM-carinata meal-based diet, and for the carinata meal. However, the combination of phytase and multicarbohydrase did improve (P < 0.05) apparent total tract digestibility, and DE and NE values for carinata meal by 9.4%, 9.5%, and 12.4%, respectively. In conclusion, the enzymes used in the current study could be added in carinata meal-based diets for growing pigs to improve the energy value.

Growth performance, organ weights, and blood parameters of nursery pigs fed diets containing increasing levels of cold-pressed canola cake.

Oilseed cakes have high oil content, and thus their inclusion in swine can lead to reduced dietary inclusion of oil, and hence reduced cost of feed. An experiment was conducted to determine effects of including Brassica napus-derived cold-pressed canola cake (CPCC) in diets for nursery pigs on growth performance, organ weights relative to live body weight (BW), and blood parameters. A total of 160 pigs (initial BW: 7.8 ± 0.9 kg), which had been weaned at 21 d of age were housed in 40 pens (4 pigs/pen) and fed 4 diets (10 pens/diet) in a randomized complete block design for 35 d. The 4 diets were corn-soybean meal (SBM)-based basal diet and the basal diet with corn and SBM replaced by 20, 30, or 40% of CPCC. The diets were fed in 2 phases, Phase 1 from day 0 to 14 and Phase 2 from day 14 to 35; and were formulated to meet NRC (2012) nutrient recommendations for nursery pigs and to have the same net energy, standardized ileal digestible amino acid, and digestible P contents. Increasing inclusion of CPCC in diets was achieved by partial replacement of corn, SBM, limestone, and mono-calcium phosphate. Growth performance was determined by phase. On day 35, 1 pig from each pen was euthanized for determining organ weights and blood parameters. The CPCC contained 7.63% moisture, and on a dry matter basis, it (CPCC) contained 39.6% crude protein, 2.32% Lys, 0.74% Met, 1.63% Thr, 0.50% Trp, 16.0% ether extract, 20.7% neutral detergent fiber, and 14.9 µmol/g of glucosinolates. Increasing dietary CPCC from 0 to 40% linearly reduced (P < 0.05) overall (day 0 to 35) average daily gain and average daily feed intake (0.440 to 0.288 kg/d and 0.739 to 0.522 kg/d, respectively). Increasing dietary CPCC from 0 to 40% resulted in a linear increase (P < 0.05) in liver weight by 0.1 g/kg of BW and in thyroid gland weight by 2.2 mg/kg of BW, but in a linear reduction (P < 0.05) in serum tetraiodothyronine (T4) level by 0.2 ng/mL for each 1% increase in CPCC at 35 d of age. No differences were observed in heart and kidney weights relative to live BW, and in serum triiodothyronine (T3) concentration. In conclusion, increasing dietary CPCC from 0 to 40% by reducing corn and SBM levels resulted in depressed growth performance, increased metabolic activity in liver and thyroid gland, and reduced serum T4 level of pigs. Thus, the amounts of CPCC included in nursery pig diets should be based on targeted growth performance and cost of other feedstuffs in relation to that of CPCC.

Enhancing the Nutritive Value of Corn Whole Stillage for Pigs via Pretreatment and Predigestion.

Corn DDGS is poorly digested by pigs. Pretreatment or predigestion of whole stillage (WS; slurry material from which DDGS is derived) can potentially improve corn DDGS digestibility. Thus, a study was conducted to determine the effects of pretreating WS with heat (160 °C and 70 psi for 20 min) alone or in combination with citric acid (10 g/L; CA), sulfuric acid (90 mM; H2SO4), or ammonia (1%), without or with subsequent multienzymatic hydrolysis for 24 h, on porcine digestibility. Dried untreated, heat-pretreated, CA-pretreated, H2SO4-pretreated, and ammonia-pretreated WS contained 23, 21, 12 19, and 18% total nonstarch polysaccharides, respectively. Pretreatment increased in vitro digestibility of dry matter of WS by ∼11 (CA) to ∼15% units (ammonia). Multienzyme hydrolysis increased in vitro digestibility of dry matter of WS by ∼6 (ammonia-treated WS) to ∼18% units (untreated WS). Thus, pretreatment or predigestion can improve the digestibility of WS and hence the resulting DDGS.

Performance and nutrient digestibility in growing pigs fed wheat dried distillers' grain with solubles-containing diets supplemented with phytase and multi-carbohydrase.

Effect of supplementing wheat dried distillers' grain with solubles (DDGS)-containing diet with enzymes on nutrient utilization by growing pigs was evaluated in two experiments. In Experiment 1, 60 pigs weighing ~30 kg were fed five diets that included a corn-based diet (Control), Control with 10% wheat DDGS (DDGS-PC), DDGS-PC without inorganic P source (DDGS-NC), and DDGS-NC plus phytase alone or with multi-carbohydrase for 4 weeks to determine average daily gain (ADG), average daily feed intake (ADFI) and gain-to-feed ratio (G:F). In Experiment 2, 30 barrows weighing 22 kg were fed five diets fed in Experiment 1 to determine nutrient digestibility and retention. Pigs fed DDGS-PC and Control diets had similar ADG and G:F. The ADG and G:F for DDGS-PC diet were higher (P < 0.05) than those for DDGS-NC diet. Phytase improved (P < 0.05) ADG, G:F, total tract P digestibility and P retention by 6.6, 8.7, 86.0 and 85.5%, respectively. Addition of multi-carbohydrase to phytase-supplemented diet did not affected growth performance, but reduced (P < 0.05) P retention. In conclusion, inclusion of 10% wheat DDGS in growing pig diet may not affect growth performance of growing pigs. Phytase supplementation to wheat DDGS-containing diet can eliminate the need for inorganic P supplement in pig diets.

Nutrient digestibility in finishing pigs fed phytase-supplemented barley-based diets containing soybean meal or canola meal as a protein source.

The effect of phytase on nutrient digestibility in finishing pigs fed barley-based diet with soybean meal or canola meal as protein source was investigated. Six ileal-cannulated barrows (70 kg initial BW) were fed five diets in a 5 x 5 Latin square design with one added column. The five diets were based on barley-soybean meal (BSBM) or barley-canola meal (BCM) without or with phytase at 500 FTU/kg, and a casein-cornstarch-based diet, which was used to estimate standardised ileal AA digestibilities. No interactions were detected between phytase and diet on any of the response criteria measured except for apparent total tract N digestibility, which was reduced in BSBM diet but not BCM diet by phytase. Phytase increased (p < 0.01) apparent ileal and total tract P digestibility in both BSBM and BCM diets by at least 17 percentage units, and tended (p < 0.10) to increase the apparent ileal digestibilities of histidine, isoleucine, threonine, valine, cysteine, glycine and tyrosine. In conclusion, the effect of phytase in barley-based diets for finishing pigs on all response criteria measured in this study, except apparent total tract N digestibility, was not influenced by protein source.

Ileal digestibility and endogenous flow of minerals and amino acids: responses to dietary phytic acid in piglets.

Effects of phytic acid (PA) on ileal mineral and amino acid (AA) digestibilities and ileal endogenous AA flow in piglets were investigated. Seven ileal-cannulated weanling pigs were fed a casein-maize starch-based diet with PA (as sodium phytate) at 0, 5, 10 or 20 g/kg in 4 x 4 Latin square design with three added columns to give seven observations per treatment. The basal diet was formulated to meet National Research Council energy and AA requirements for piglets. The respective digestibility and endogenous lysine loss were determined by indicator and homoarginine methods. The apparent ileal digestibility (AID) of Na, K and P was linearly and quadratically reduced (P < 0.05) by increased dietary PA concentration, whereas that of Ca and Mg was only linearly reduced (P < 0.05) by the dietary PA. The AID values for Mg and Na were negative ( - 0.03 and - 0.18, respectively) when PA was supplemented at 20 g/kg. The AID of isoleucine, leucine and valine responded quadratically to dietary PA concentration, though the differences between the AID values of the AA due to change in dietary PA concentration were marginal (at most by 1.8 percentage units). Furthermore, dietary PA did not affect (P>0.05) endogenous AA losses. The results suggest that PA has limited effect on the digestibility and endogenous losses of AA in piglets, but can reduce AID of Mg and Na partly by increasing endogenous losses of these minerals as evidenced by their negative AID values.