Patrick Guggenbuhl

Effects of dietary supplementation with a protease on the apparent ileal digestibility of the weaned piglet

The effects of an acid-stable protease (RONOZYME ProAct) supplemented to a corn (Zea mays)-soybean (Glycine max) meal-based diet on apparent ileal digestibility (AID) of nutrients were evaluated in 120 weaned piglets (28 d old; 8.17 ± 0.90 kg). Pigs were divided into 2 equal groups and had free access to mash diet containing 0.4% Cr(2)O(3) as indigestible marker [basal diet (Std)] or this diet supplemented with RONOZYME ProAct at 15,000 PROT [the amount of enzyme that releases 1 μmol of pnitroaniline from 1 μM of substrate (Suc-Ala-Ala-Pro-Phe-p-nitroaniline) per min at pH 9.0 and 37°C)/kg (ProA). The ileal content was collected for the digestibility determination after euthanasia of 35 piglets of each group after 14 d of study and 25 piglets of each group after 29 d. Compared to group Std, AID of CP was increased (P < 0.05) after 29 d of treatment in group ProA. The AID of the indispensable AA, Met + Cys, and branched-chain AA was increased (P < 0.05) at the end of the study. In the protease supplemented pigs, the AID of the individual AA was not improved after 14 d of treatment whereas it was increased (P < 0.05) at the end of the experiment for Arg, Asp + Asn, Glu + Gln, His, Ile, Lys, Phe, Thr, Tyr ,and Val. In conclusion, dietary protease supplementation increased AID of AA in piglets.

In vitro and in vivo degradation of myo-inositol hexakisphosphate by a phytase from Citrobacter braakii

Phytases (EC 3.1.3) are widely used in animal feed to increase the availability of phosphorus and decrease the anti nutritive effect of myo-inositol hexakisphosphate (InsP6). The aim of this work was to investigate the stereospecific degradation of InsP6 in vitro and in vivo by a phytase from Citrobacter braakii (C. braakii), and to study gastric survival of the phytase as well as the site of action in the gastrointestinal tract. The in vitro results showed that the C. braakii phytase belongs to the group of 6-phytases (EC 3.1.3.26). However, in approximately one out of 10 instances the phytase initiated hydrolysis at the D-3 (L-1) position, demonstrating that phytase specificity is not unambiguous. Following the main degradation pathway, InsP6 was degraded by stepwise removal of the phosphate groups on positions 6/1/5. The stereospecificity was found to be similar under in vitro and in vivo conditions. The phytase was found to be stable in the gastric environment and to be active in the stomach and possibly also in the proximal small intestine. While InsP4 was accumulated under in vitro conditions this was not the case in vivo, where both InsP5 and InsP4 were seen to be hydrolysed in the small intestine, possibly as a combined action of the C. braakii phytase and endogenous phosphatases present in the mucosa. The ability of the C. braakii phytase to focus its activity on degrading InsP6 to InsP4 is believed to be a favourable complement to the endogenous phosphatases.

Effects of a 6-phytase on the apparent ileal digestibility of minerals and amino acids in ileorectal anastomosed pigs fed on a corn–soybean meal–barley diet

Phosphorus of plant-based feedstuffs for monogastric animals is mainly in the form of phytic P, which has a very low bioavailability. The nondigested phytic P may contribute to P pollution. Furthermore, phytic acid may reduce digestibility of other minerals and protein. This study evaluated effects of the microbial 6-phytase RONOZYME HiPhos on apparent ileal digestibility of P, phytic acid, Ca, CP, energy, and AA in six 60-d-old ileorectal anastomosed pigs. In a duplicated 3 × 3 Latin square design, pigs had free access to alternatively a corn (Zea mays)-soybean (Glycine max) meal-barley (Hordeum vulgare)-based diet or this diet supplemented with RONOZYME HiPhos at either 500 units/kg (RH500) or 1000 units/kg (RH1000). Pigs fed diets supplemented with RH500 or RH1000 increased (P < 0.05) digestibility of P, Ca, and Lys. Pigs fed diet RH1000 increased (P < 0.05) digestibility of CP, total AA, indispensable AA, Glu + Gln, His, Gly, Ala, Tyr, Leu, Phe, and Met. Similar to growth trials with increased total tract digestibility of P and Ca, phytase increased apparent ileal digestibility of these indispensable minerals and phytate. The phytase increased digestibility of CP and indispensable AA indicating a better availability of plant-based proteins.

Comparative effects of three phytases on the phosphorus and calcium use in the weaned piglet

The addition of phytase to swine diets has generally increased P digestibility and consequently reduced fecal excretion of P. The comparative effects on P and Ca digestibility of dietary inclusion of 5 different phytases were evaluated in the weaned piglet. RONOZYME HiPhos is a microbial 6-phytase produced by synthetic genes, mimicking a gene from Citrobacter braakii, and was compared to the Escherichia coli-derived phytases Phyzyme and OptiPhos. In total, 112 weaned piglets (28 d old) were allocated to 8 equal groups of 14 animals. Pigs were fed for 29 d a vegetable-based diet without addition of mineral P [Co(-)] or this diet supplemented with 12 g/kg feed of CaHPO(4) [Co(+)] or with HiPhos at 1000 units/kg (H1000) or 1500 units/kg (H1500), Phyzyme at 500 units/kg (P500) or 750 units/kg (P750), or OptiPhos at 500 units/kg (O500) or 750 units/kg (O750). All phytases reduced (P < 0.05) fecal P concentration and excretion and increased (P < 0.05) P digestibility and apparent P absorption. The digestible P equivalences of H1000, H1500, P500, P750, O500, and O750 were 0.94, 1.50, 0.67, 0.92, 0.58, and 1.11 g of full available P/kg of feed, respectively. Calcium digestibility was increased (P < 0.05) and Ca excretion reduced (P < 0.05) by the phytases. The 3 phytase preparations increased digestibility and apparent absorption of P and Ca in weaned piglets fed a diet containing P exclusively from plant origin.

The degradation of arabinoxylan-rich cell walls in digesta obtained from piglets fed wheat-based diets varies depending on digesta collection site, type of cereal, and source of exogenous xylanase

The objective of the present study was to compare the ability of experimental and commercial xylanases to degrade, in vitro, the arabinoxylan (AX) fraction in digesta from 28-d-old piglets fed a wheat (Triticum aestivum)-based diet (49% wheat). Pigs were euthanized at 1, 2, 3, or 4 h after feeding; stomach and ileum contents were isolated and frozen and later used for the in vitro studies. Xylan solubilization provided information regarding the ability of the enzymes to degrade AX during the harsh in vivo conditions prevailing in the gastrointestinal tract. The hydrolytic capacity of a commercial xylanase was compared with that of an experimental xylanase using stomach digesta (pH 1.8) obtained at 4 h after feeding. Relative to the control, both enzymes increased (P < 0.001) xylan solubilization 3-fold. In the ileal digesta (1 h), xylan solubilization was increased by 36% (P < 0.001). Inclusion of arabinofuranosidases (Ara f) with xylanases increased xylan solubilization in stomach samples (P = 0. 007 and P = 0. 030) but not in ileal samples (P = 0.873 and P = 0.997). Our results illustrate clearly the importance of using different conditions and substrates when enzyme performance is studied in vitro as a prescreening tool for setting up in vivo trials.

Growth performance of nursery and grower-finisher pigs fed diets supplemented with benzoic acid

Two experiments were conducted to investigate the efficacy of benzoic acid on the growth performance of nursery and grower-finisher pigs. A randomized complete block design was used in both experiments with the initial body weight as the blocking factor. There were 3 treatments corresponding to 3 dietary levels of benzoic acid: 0, 0.3%, and 0.5%. In experiment 1, a total of 144 PIC L1050 barrows (initial body weight 7.1 ± 0.6 kg) were used with each treatment replicated 8 times. In experiment 2, a total of 288 PIC L1050 barrows (initial body weight 36.1 ± 3.6 kg) were used with each treatment replicated 16 times. There were 6 barrows in each replicate pen for both experiments. Experiments 1 and 2 lasted 28 and 70 days, respectively. In experiment 1, average daily gain (ADG) of all growth phases increased linearly (P < 0.05) with increasing supplementation of benzoic acid, which led to a linear improvement in average body weight on d 28 (P < 0.05). There was also an improvement in feed conversion ratio (FCR) of d 0 to 14 (linear effect: P < 0.05) and in average daily feed intake (ADFI) of d 14 to 28 and d 0 to 28 (linear effect: P < 0.01). In experiment 2, ADG during d 0 to 35 and d 35 to 70 and average body weight on d 35 improved linearly (P < 0.05) with increasing supplementation of benzoic acid. Average daily gain of d 0 to 70 and average body weight on d 70 increased significantly in a both linear and quadratic manner. There was a linear improvement in FCR in all growth phases (P < 0.05). In conclusion, the dietary inclusion of benzoic acid at the supplementation levels of 0.3% and 0.5% significantly improved the growth performance of nursery and grower-finisher pigs in the current study; the nursery pigs responded to the dietary supplementation of benzoic acid up to 0.5% linearly while the grower-finisher pigs achieved the optimal ADG at the calculated supplementation level of 0.36%.