J. Broz

Influence of benzoic acid and dietary protein level on performance, nitrogen metabolism and urinary pH in growing-finishing pigs

Abstract An experiment was conducted to examine the effect of benzoic acid and two dietary protein levels on pig performance, nitrogen balance and urinary pH. A total of 24 crossbred barrows (26 kg to 106 kg BW) received one of four diets: low protein level with and without 1% benzoic acid (LP− and LP+, respectively) and high protein level with and without 1% benzoic acid (HP− and HP+, respectively). The animals were fed restrictively grower and finisher diets and were kept in metabolic cages in weeks 3, 6, 9, and 12 of the experiment. The addition of benzoic acid did not improve weight gain and feed conversion ratio. N-intake and digested N were only influenced by dietary protein level (p<0.01), while N-balance was similar in all four diets. Dietary benzoic acid improved N-digestibility in the grower period (p<0.01) but not in the finisher period. The addition of benzoic acid reduced urinary pH by about one pH-unit in both feeding periods independent of the protein level of the diet (p<0.01) and increased the concentration of urinary hippuric acid markedly (p<0.01). The results of this study indicate a positive influence of dietary benzoic acid on pigs especially in case of feeding a low protein diet in the grower period.

Influence of benzoic acid and phytase in low-phosphorus diets on bone characteristics in growing-finishing pigs.

In 2 simultaneous experiments (Exp. 1 and Exp. 2), the effects of benzoic acid (BA) and phytase (Phy) in low-P diets on bone metabolism, bone composition, and bone stability in growing and growing-finishing pigs were examined. Experiment 1 was conducted with 16 crossbred gilts in the BW range of 25 to 66 kg of BW, whereas in Exp. 2, 32 crossbred gilts (25 to 108 kg of BW) were used. All pigs were individually housed in pens and restrictively fed 1 of 4 diets throughout the experiment. Total P content of the wheat-soybean diets was 4 g/kg (all values on an as-fed basis). The experimental diets were 1) unsupplemented control diet; 2) control diet with 0.5% BA; 3) Phy diet with 750 Phy units (FTU) of Phy/kg and no BA; and 4) PhyBA, control diet with 750 FTU of Phy/kg and 0.5% BA. Blood samples were taken at the beginning of the experiment, wk 3 (only for pigs in Exp. 1), wk 6, and before slaughter to determine P and Ca in serum and concentrations of total alkaline phosphatase, serum crosslaps (marker for bone resorption), and osteocalcin (marker for bone formation). Ash, P, and Ca contents of bones and bone stability were examined using the left metatarsal bones and tibia of the pigs after slaughter. Benzoic acid did not influence any of the blood variables (P > 0.09). The addition of Phy increased (P < or =0.03) P concentration in serum from 2.71 +/- 0.08 to 3.03 +/- 0.07 mmol/L at wk 3 and content of serum crosslaps from 0.39 +/- 0.02 to 0.45 +/- 0.02 ng/mL at wk 6 and decreased (P < 0.05) osteocalcin at wk 6 by 160 ng/mL. No long-term effect of diets on serum mineral concentrations, alkaline phosphatase, and bone markers in serum could be detected. Benzoic acid negatively affected (P < or = 0.03) Ca content in bones and distal bone mineral density, especially in the younger pigs. In the control diet with 0.5% BA and the control diet with 750 FTU of Phy/kg and 0.5% BA, the CA content in bones and distal bone mineral density were reduced by 6 and 11%, respectively. Throughout the whole growing and finishing period, Phy increased (P < or =0.02) ash, P, and Ca contents in bones by 29.4, 4.8, and 11.6 g/kg of DM, respectively. Bone mineral density and bone mineral content were greater in diets with Phy (P < or = 0.03), as well as breaking strength of tibia (+22%) and metatarsal bones (+27%; P < 0.01). The results of this study indicate that for a healthy skeleton, BA should not be used in low-P diets without the addition of Phy.

Effects of lactoferrin feeding on growth, feed intake and health of calves.

Abstract Lactoferrin (LF) exhibits a broad spectrum of anti-microbial properties and may have regulatory functions in the immune system. In the present study, 40 calves (20 males, 20 females) were used to examine the effects of supplemental bovine LF added to colostrum and milk replacer (at 0.16%) on health, weight development and feed intake during a 70-day experimental period. The calves were allocated to a treatment group (n = 20) and a control group (n = 20); the groups were balanced in terms of sex, live weight and date of birth. Body weight and feed intake were measured at regular intervals. Blood and colostrum samples were collected to determine the content of IgG. In addition, colostrum and milk replacer samples were analysed for their LF concentrations. Significantly higher IgG values were observed in the LF treated than in the control group during the entire feeding experiment from week 2 to week 6. Calves receiving LF had less days of disease with less serious cases of diarrhoea than the control group. Body weight and feed intake were not significantly different between the treatments; in male calves LF-treated animals tended towards higher weight gains. This study indicates that LF is advantageous for health and may therefore be a beneficial supplement in the diets for neonatal calves.

Influence of benzoic acid in high fibre diets on nutrient digestibility and VFA production in growing/finishing pigs

In a feeding trial with 32 crossbred gilts (13–108 kg bodyweight) the effect of benzoic acid (5 g/kg diet) in low (NDF: 150 g/kg DM) and high (NDF: 202 g/kg DM) fibre diets on performance and apparent nutrient digestibility was examined. The animals were restrictively fed one of four grower and finisher diets: low fibre diet without and with benzoic acid (LF− and LF+), and a high fibre diet without and with benzoic acid (HF− and HF+). At 56 kg bodyweight, four animals per diet were slaughtered to obtain data on volatile fatty acid (VFA) production in the gut. In the grower period, digestibility of nitrogen, energy and neutral detergent fibre was positively influenced by benzoic acid (p < 0.01) and reduced by fibre addition (p < 0.01). The concentration of butyric acid in caecum and colon was increased by benzoic acid (p < 0.05). Dietary fibre content did not influence VFA concentrations. It is concluded that the addition of benzoic acid helped animals to utilise high fibre diets better.

The supplementation of low-P diets with microbial 6-phytase expressed in Aspergillus oryzae improves P digestibility in sows

Two trials were conducted to evaluate a novel microbial 6-phytase expressed in Aspergillus oryzae (Ronozyme HiPhos; DSM Nutritional Products, Basel, Switzerland) in gestating and lactating sows. In the first trial, 24 sows (Duroc × Landrace; 223 kg BW) were offered, at 16 d of gestation, a low-P control diet (formulated to provide 4.0 g total P/kg; 1.5 g digestible P/kg) supplemented with 0, 500, or 1000 phytase activity (FYT)/kg of phytase. Two weeks later, fresh feces were sampled from all sows and the apparent total tract digestibility of P was measured using TiO(2) as indigestible marker. Phytase supplementation did not (P > 0.10) affect the total tract digestibility of P but reduced (P < 0.05) P concentration in feces (from 14.5 to 12.0 and 12.0 g/kg DM). In the second trial, 32 lactating sows (Duroc × Landrace; 282 kg BW) were used. They were offered, at 7 d of lactation, a low-P control diet (formulated to provide 6.1 g total P/kg; 3 g digestible P/kg) or the same diet supplemented with 500 FYT/kg of phytase. After 2 wk, fresh feces were sampled from all sows and the apparent total tract digestibility of P was measured using TiO(2) as indigestible marker. Phytase supplementation improved (P < 0.001) the apparent total tract digestibility of P from 27.5 to 38.7% and reduced (P < 0.001) P concentration in feces (from 27.5 to 21.4 g/kg DM). In conclusion, the microbial 6-phytase tested increased the apparent total tract digestibility of P in sows and reduced P excretion in feces.

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.

The supplementation of low-P diets with microbial 6-phytase expressed in Aspergillus oryzae increases P and Ca digestibility in growing pigs

A trial was conducted to evaluate the dose response of a novel microbial 6-phytase expressed in Aspergillus oryzae (Ronozyme HiPhos; DSM Nutritional Products, Basel, Switzerland) in pigs. Forty-eight individually housed pigs (Landrace × Pietrain; 52 kg BW; 24 males and 24 females) were distributed among 6 experimental treatments consisting of a low-P diet (3.5 g P/kg; 1.1 g digestible P/kg), which was supplemented with 500, 1000, 2000, or 4000 units of phytase activity/kg, and a standard-P diet (4.5 g P/kg; 1.8 g digestible P/kg) that was supplemented with CaHPO(4). After 17 d, fresh feces were sampled from all pigs and the apparent total tract digestibility of DM, OM, ash, P, and Ca was measured using TiO(2) as indigestible marker. Blood samples were also obtained from each pig and serum was analyzed for P and Ca concentrations. The nonsupplemented low-P diet increased Ca and reduced P blood serum concentrations (P < 0.05) relative to the standard-P diet (10.8 vs. 10.2 and 6.7 vs. 7.7 mg/dL, respectively). Phytase supplementation of the low-P diet reduced Ca (from 10.8 to 9.9 mg/dL; linear, P < 0.001) and increased P concentrations (from 6.7 to 8.0 mg/dL; linear and quadratic, P < 0.001) in serum and reduced P concentration in feces (from 13.7 to 7.6 g/kg DM; linear and quadratic, P < 0.001). Phytase improved the total tract digestibility of P (from 29.0 to 62.3%; linear and quadratic, P < 0.001 and P < 0.05), Ca (from 54.0 to 75.7%; quadratic, P < 0.01), and ash (from 46.2 to 57.7%; quadratic, P < 0.01). In conclusion, the microbial 6-phytase tested improves the apparent total tract digestibility of P in growing pigs and reduces P excretion in feces in a dose-dependent manner.

The effects of supplementation of a novel bacterial 6-phytase on mineral digestibility and plasma minerals in lactating sows

Pigs digest P in plant feedstuffs poorly because pigs do not produce sufficient endogenous phytase to hydrolyze P from phytate (inositol hexaphosphate). Supplementation of phytase to diets of piglets and grower-finisher pigs increased digestibility of minerals including P and Ca; however, data on phytase efficacy in lactating sows are scarce. Therefore, effects of adding a bacterial 6-phytase expressed in a strain of Aspergillus oryzae (Ronozyme HiPhos; DSM Nutritional Products, Basel, Switzerland) on apparent total tract digestibility (ATTD) of P and Ca was assessed in 45 lactating sows. Three diets were prepared: (i) positive control (PC; 0.52% available P), a regular sow diet containing inorganic P, (ii) negative control (NC; 0.20% available P) without inorganic P, and (iii) NC + 500 units of phytase/kg diet. Each diet was fed randomly to 15 sows for 21 d (from 5 d prior to farrowing to 15 d after farrowing). At day 15 after farrowing, ATTD of P did not differ between PC and NC. Phytase supplementation to NC increased (P < 0.05) ATTD of P from 34 to 46% compared to NC but did not affect (P > 0.05) ATTD of CP and Ca. On day 1 after farrowing, plasma P was 0.66 mmol/L lower (P < 0.05) in sows fed NC than PC. Phytase supplementation to NC increased (P < 0.05) plasma P by 0.40 mmol/L on day 1 but not on day 15 after farrowing. In conclusion, phytase supplementation increased P bioavailability in lactating sows.