Phosphorus digestibility and phytate degradation in pigs fed wheat-based diets with different intrinsic phytase activity and added microbial phytase.

The objective of this study was to investigate the effect of variation in wheat-derived phytase activity on myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP6) degradation, inositol phosphate (InsP) isomer concentration and phosphorus (P) digestibility in pigs fed wheat-based diets. Additional effects of a microbial phytase supplementation were also studied. Three wheat genotypes (W1-W3) with an analysed phytase activity between 2760 and 3700 FTU/kg were used to formulate four experimental diets that included soybean meal and rapeseed meal but did not contain a mineral P supplement. DietW1-DietW3 only differed in the included wheat genotypes (W1-W3) at an inclusion level of 400 g/kg. DietW3+ contained W3 and a commercial 6-phytase supplementation at 500 FTU/kg diet. Eight barrows with an initial body weight of 27 kg were fitted with a simple T-cannula at the distal ileum and assigned to the four dietary treatments in a completely randomised row column design. The experiment included four periods of 12 d each. The first 5 d of each period were for diet adaptation, followed by collection of faeces (4 d), ileal digesta (2 d), and blood (last day). In DietW1-DietW3, the mean precaecal (pc) InsP6 disappearance was 48% and the mean pc P digestibility was 37% without a significant effect of the wheat genotype. The InsP6 disappearance measured in the faeces was close to complete in all treatments, and faecal P digestibility was not significantly affected by the wheat genotype (36% overall). The addition of microbial phytase caused a significant increase in pc InsP6 degradation (to 79%) and pc and total tract P digestibility (to 53% and 52%, respectively). The concentration of InsP6 degradation products in ileal digesta was not significantly affected by the wheat genotype, except for that of Ins(1,2,3,4,6)P5 and myo-inositol, which were higher in DietW3 than in DietW1 and DietW2. The added microbial phytase significantly reduced the concentration of InsP5 isomers in the ileal digesta and increased the concentrations of lower InsP isomers and myo-inositol. There were no significant effects of the added microbial phytase on pc amino acid digestibility; however, the wheat genotype exerted significant effects on the pc digestibility of Cys, Gly and Val. It was concluded that an increase in the intrinsic phytase activity of wheat achieved by crossbreeding was not reflected in InsP6 degradation and P digestibility in pigs fed wheat-based diets.

Improved simple T-cannula technique to facilitate surgery and daily skin care of growing pigs.

In order to further increase the stability of the cannula behind the ribs and to facilitate cannula exteriorization in growing pigs, the present study aimed to evaluate whether elongation of the cannula flange could increase the stability of the cannula behind the ribs and to develop a tool to improve the exteriorization of the cannula through the ribs. Moreover, it was assessed whether a special skin protection paste and soft polyurethane foam material used in daily skin care could prevent erythema around the fistula. The feasibility of both, the modified simple T-cannula and daily skin care procedure, was evaluated in a digestibility experiment. Simple T-cannulae were made of high-molecular-weight polyethylene and inserted into the distal ileum of eight growing pigs (average body weight at surgery 30 kg). Modifications in the cannula design included a longer flange (11 cm) that was narrowed from the center to the ends and a bending of the flange to adapt it to the curve of the costal arch. In order to reduce the damage to the thread on the outer cannula barrel during surgery, a special surgical plug in conjunction with a screw thread on the inside of the barrel was developed. With respect to the daily cleaning of the fistula, a special skin protection paste was applied on the skin around the fistula to create a waterproof film that entirely sealed the skin. Additionally, foam material was inserted between the retaining ring and the skin to absorb the leaking digesta. Monitoring of the pigs throughout the trial showed that modifications in cannula design proved to be useful as they facilitated exteriorization of the cannula through the ribs and stability of the cannula behind the ribs. Moreover, the use of the skin protection paste and foam material during postsurgical treatment of growing pigs effectively prevented skin irritation around the flank area.

Phytate degradation cascade in pigs as affected by phytase supplementation and rapeseed cake inclusion in corn-soybean meal-based diets.

Two experiments (Exp.) with ileally cannulated growing barrows were conducted. The concentrations of positional inositol phosphate (InsP) isomers in ileal digesta and feces were determined, as well as the prececal and total tract phytate (InsP6) hydrolysis, and digestibility of dry matter, P, Ca, nitrogen, and gross energy. Prececal amino acid (AA) digestibility and digestive enzyme activities in ileal digesta were also studied. In both Exp., pigs had an initial body weight (BW) of 28 kg and were completely randomized to a Double Latin Square Design with eight pigs, four diets, and three periods of 12 d each. Feces and ileal digesta were collected for 5 d and 2 d, respectively. Pigs were housed individually in stainless steel metabolic units. Water was available ad libitum and feed was provided two times daily at an amount of 4% of mean BW. In Exp. 1, pigs received a corn-soybean meal (SBM)-based diet that was supplemented with 0, 750, 1,500, or 3,000 FTU of a microbial phytase/kg diet. In Exp. 2, pigs were allotted to a 2 × 2 arrangement of diets based on corn and SBM or an SBM-rapeseed cake (RSC) mix and phytase supplementation at 0 or 1,500 FTU/kg of diet. In ileal digesta of pigs fed without the phytase supplement, the dominating InsP isomers beside InsP6 were InsP5 isomers. The InsP pattern in ileal digesta changed with the inclusion of microbial phytase in both Exp., as there was a remarkable increase in Ins(1,2,5,6)P4 concentration (P < 0.001). In both Exp., the myo-inositol concentration in ileal digesta was greater upon phytase addition (P < 0.001). Without phytase supplementation, prececal and total tract P digestibility were low, whereas hardly any InsP6 was excreted in feces. There was no difference between prececal and total tract P digestibility values. For most AA studied in Exp. 2, prececal digestibility was lower (P < 0.01) when the diet contained RSC. However, phytase supplementation did not significantly affect prececal AA digestibility in both Exp. The present study showed that InsP6 disappearance by the end of the ileum can be increased up to around 90% in SBM- and SBM-RSC-based diets when microbial phytase is supplemented, but prececal P digestibility hardly exceeded 60%. The study confirms that pigs cannot benefit from a remarkable InsP6 degradation in the hindgut.

Evaluation of analytical and statistical approaches for predicting in vitro nitrogen solubility and in vivo pre-caecal crude protein digestibility of cereal grains in growing pigs.

Different analytical (enzyme system and near-infrared spectroscopy (NIRS)) and statistical (single and multiple regressions) approaches were used to predict in vivo standardized pre-caecal digestibility (PCD) of crude protein (CP) and amino acids (AA) in cereal grains for growing pigs as well as in vitro nitrogen (N) solubility. Furthermore, different chemical and physical characteristics were categorized (e.g. crude nutrients, AA, minerals, fibre components or combinations of these) and used for generating prediction equations. There were strong linear relationships (p < .05) between in vivo PCD of CP and essential AA and in vitro N solubility when grain species was considered as covariate in the model. Predicting in vivo PCD values using various chemical and physical characteristics produced inconsistent results among different grain species and AA and could therefore not be used for predicting PCD. It is possible to predict in vitro N solubility from chemical and physical characteristics for some grain species. However, the relationships between some of these categories and the in vitro N solubility were not consistent and not always causative or physiologically explainable. The R2 of NIRS for predicting in vitro N solubility was at a relatively high level (up to R2  = 0.80). This level of R2 indicates that a classification of the grain samples in, for example, high, medium and low in vitro N solubility levels is possible, but it does not allow for a quantitative prediction of the in vitro N solubility. In conclusion, the present database can be used for establishing a ranking of different cereal grain species for PCD of CP and essential AA values. However, it was not possible to create clear prediction equations for in vivo or in vitro digestibility values. Therefore, greater variation within grain species, for example due to different growing and harvesting conditions, is warranted for predicting PCD values of individual grain samples.

Effect of microbial phytase supplementation on P digestibility in pigs: a meta-analysis.

The objectives of this meta-analysis were to determine to which extent phosphorus (P) digestibility and digestible P concentration in pig diets were increased by phytase supplementation and to quantify factors that potentially influence effects of phytase supplementation. A data set with a total of 547 data lines was compiled from 88 experiments published in 74 peer-reviewed papers between 2007 and April 2019. An exponential model was determined as more suitable to describe the response of P digestibility to phytase supplementation than a polynomial model. Phytase supplementation increased P digestibility by 25.6 percentage points (standard error (SE) = 1.54) to a plateau at 64.9% (SE = 1.82). The digestible P concentration was increased by phytase supplementation in the order of 1.01 g/kg (SE = 0.102) to a plateau at 2.62 g/kg (SE = 0.122). Goodness-of-fit criteria were R2 = 0.780 and root mean square error = 7.55% for P digestibility, and R2 = 0.691 and root mean square error = 0.48 g/kg for digestible P concentration. Consideration of further factors such as mineral P supplementation (yes or no), ad libitum vs. restrictive feeding, mixed diets vs. single feed ingredients, sex and age of pigs did not increase the accuracy of prediction in this data set. Some of these traits exhibited responses, but they likely are artefacts generated through the imbalanced structure of the data set. Effects of dietary total P, phytate (InsP6), InsP6-P to total P ratio, and Ca on the effect of supplemented phytase were not quantifiable. The present meta-analysis showed that responses to phytase supplementation can be well predicted although variation in P digestibility and digestible P concentration in the data set was high. Overall, predicted effects of phytase on P digestibility well corresponded to predictions made 25 years ago.

Effect of Bacillus subtilis and Bacillus licheniformis supplementation in diets with low- and high-protein content on ileal crude protein and amino acid digestibility and intestinal microbiota composition of growing pigs.

BACKGROUND: Bacillus spp. seem to be an alternative to antimicrobial growth promoters for improving animals' health and performance. However, there is little information on the effect of Bacillus spp. in combination with different dietary crude protein (CP) levels on the ileal digestibility and microbiota composition. Therefore, the objective of this study was to determine the effect of Bacillus spp. supplementation to low- (LP) and high-protein diets (HP) on ileal CP and amino acid (AA) digestibility and intestinal microbiota composition. METHODS: Eight ileally cannulated pigs with an initial body weight of 28.5 kg were randomly allocated to a row-column design with 8 pigs and 3 periods of 16 d each. The assay diets were based on wheat-barley-soybean meal with two protein levels: LP (14% CP, as-fed) and HP diet (18% CP, as-fed). The LP and HP diets were supplemented with or without Bacillus spp. at a level of 0.04% (as-fed). The apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP and AA was determined. Bacterial community composition from ileal digesta was analyzed by Illumina amplicon sequencing and quantitative real-time PCR. Data were analyzed as a 2 × 2 factorial design using the GLIMMIX procedures of SAS. RESULTS: The supplementation with Bacillus spp. did not affect both AID and SID of CP and AA in growing pigs. Moreover, there was no difference in AID of CP and AA between HP and LP diets, but SID of cystine, glutamic acid, glycine, and proline was lower (P < 0.05) in pigs fed the HP diets. The HP diets increased abundance of Bifidobacterium spp. and Lactobacillus spp., (P < 0.05) and by amplicon sequencing the latter was identified as predominant genus in microbiota from HP with Bacillus spp., whereas dietary supplementation of Bacillus spp. increased (P < 0.05) abundance of Roseburia spp.. CONCLUSIONS: The HP diet increased abundance of Lactobacillus spp. and Bifidobacterium spp.. The supplementation of Bacillus spp. resulted in a higher abundance of healthy gut associated bacteria without affecting ileal CP and AA digestibility, whereas LP diet may reduce the flow of undigested protein to the large intestine of pigs.

Methodological impact of starch determination on starch content and ileal digestibility of starch in grain legumes for growing pigs.

BACKGROUND: Grain legumes represent a valuable energy source in pig diets due to their high starch content. The present study was conducted to determine the content and apparent ileal digestibility (AID) of starch in different grain legume cultivars for pigs by means of both a polarimetric and enzymatic method for starch determination. METHODS: Three experiments were conducted with six barrows each which were fitted with ileal T-cannulas. In total, 18 diets including six different cultivars of faba beans (Vicia faba L.) and peas (Pisum sativum L.), five different cultivars of lupins (Lupinus luteus L., Lupinus angustifolius L.), and one diet with a soybean meal (SBM) were fed. RESULTS: The starch content of faba beans and peas was greater (P < 0.05) when determined polarimetrically than enzymatically (438 vs. 345 g/kg dry matter (DM) in faba beans and 509 vs. 390 g/kg DM in peas, respectively). Considerable lower starch contents were obtained in lupins and SBM, with 82 and 48 g/kg DM (analyzed polarimetrically) and <1.1 and 3 g/kg DM (analyzed enzymatically), respectively. Mean values for contents of neutral detergent fiber (NDF) and acid detergent fiber (ADF) in grain legumes ranged from 111 and 79 g/kg DM in peas to 248 and 207 g/kg DM in lupins, respectively. Contents of condensed tannins in the colored flowered faba bean cultivars ranged from 2.1 to 7.4 g/kg DM. The AID of starch was greater (P < 0.05) in pea than in faba bean cultivars, and using the polarimetric starch determination method resulted in greater (P < 0.05) digestibility values than using enzymatic starch analysis (84 vs. 80% in faba beans and 86 vs. 83% in peas). Moreover, AID of starch differed (P < 0.05) within pea cultivars and starch digestibility in faba beans decreased linearly (P < 0.05) as the content of condensed tannins increased. However, there was no relationship between contents of NDF and ADF and AID of starch in pea and faba bean cultivars. CONCLUSION: Both contents and AID of starch in grain legumes can vary as influenced by the analytical method used for starch determination. Generally, starch digestibility is greater when measured by polarimetric rather than enzymatic methods.