Investigations on Genetically Modified Maize (Bt-Maize) in Pig Nutrition: Fattening Performance and Slaughtering Results

A grower finisher performance trial with forty-eight pigs was designed to compare the growth performance of pigs fed diets containing either genetically modified (GM) Bt-maize (NX6262) or its parental maize (Prelude) line. During the experiment, the pigs were fed with a grower and a finisher diet both containing 70% maize investigated in a previously study which showed that they contained similar ME values and digestibility of crude nutrients. The pigs with an initial live weight of 23.9 ± 3.0kg were allotted to single boxes. During a 91 days growing period the pigs of both groups recorded equal performance in daily weight gain ( j W) 815 ± 93 vs. 804 ± 64g/d depending on equal amounts of feed intake 1.95 ± 0.15 vs . 1.94 ± 0.15kg/d (parental vs. transgenic). The results confirm equal performance among growing-finishing pigs fed parental or genetically modified maize containing diets. For slaughtering the pigs were divided into 4 groups with a different duration of the finishing period. After slaughtering the carcass characteristic were registered.     

Investigation on the precaecal and faecal digestibility of lactulose and inulin and their influence on nutrient digestibility and microbial characteristics

This study was conducted to determine the pre-caecal and faecal digestibility of lactulose and inulin and the influence of these substances on nutrient digestibility and microbial characteristics. In metabolic trials three of six male growing pigs (German Landrace?×?Pietrain) were fitted with an ileo-rectal anastomosis (IRA) in end-to-end technique with preserved ileo-caeco-colic valve. The metabolic trials were conducted from day 21?–?63 after surgery. The remaining pigs were used as intact partners (IN) for the IRA pigs. The experimental diets, based on corn, wheat, barley and soybean meal, were supplemented with either 1.5% lactulose or 2% inulin in replacement of diatomaceous earth (control). Pre-caecal digestibility of lactulose and inulin was assessed to be 79 and 98%, respectively, faecal digestibility was determined as 100%. The supplementation of lactulose and inulin had only minor effects on the pre-caecal and faecal digestibility of nutrients. Significant differences in nutrient digestibility were obvious between IRA and IN pigs, whereas the IRA pigs showed lower digestibility values with the exception of ether extracts (EE). Bacterial population in the digesta of IRA and IN pigs were not affected by the experimental diets except the concentration of gram-negative anaerobes, which inclined when the IRA pigs received the lactulose diet. The pH of chyme was significantly lower than the pH of faeces, however the pH was unaffected by the different supplemented diets. The concentration of volatile fatty acids (VFA) in pre-caecal chyme decreased significantly when IRA pigs received the lactulose supplemented diet whereas VFA in faeces were unaffected by the supplementation. IRA pigs administered with lactulose excreted more N via the urine, but the nitrogen balance remained unaffected. From the present investigation it can be concluded that lactulose and inulin did only partly or scarcely fulfill the expectation of acting as prebiotics in pigs.     

Investigation on the precaecal and faecal digestibility of lactulose and inulin and their influence on nutrient digestibility and microbial characteristics

This study was conducted to determine the pre-caecal and faecal digestibility of lactulose and inulin and the influence of these substances on nutrient digestibility and microbial characteristics. In metabolic trials three of six male growing pigs (German Landrace x Pietrain) were fitted with an ileo-rectal anastomosis (IRA) in end-to-end technique with preserved ileo-caeco-colic valve. The metabolic trials were conducted from day 21-63 after surgery. The remaining pigs were used as intact partners (IN) for the IRA pigs. The experimental diets, based on corn, wheat, barley and soybean meal, were supplemented with either 1.5% lactulose or 2% inulin in replacement of diatomaceous earth (control). Pre-caecal digestibility of lactulose and inulin was assessed to be 79 and 98%, respectively. faecal digestibility was determined as 100%. The supplementation of lactulose and inulin had only minor effects on the pre-caecal and faecal digestibility of nutrients. Significant differences in nutrient digestibility were obvious between IRA and IN pigs, whereas the IRA pigs showed lower digestibility values with the exception of ether extracts (EE). Bacterial population in the digesta of IRA and IN pigs were not affected by the experimental diets except the concentration of gram-negative anaerobes, which inclined when the IRA pigs received the lactulose diet. The pH of chyme was significantly lower than the pH of faeces, however the pH was unaffected by the different supplemented diets. The concentration of volatile fatty acids (VFA) in pre-caecal chyme decreased significantly when IRA pigs received the lactulose supplemented diet whereas VFA in faeces were unaffected by the supplementation. IRA pigs administered with lactulose excreted more N via the urine, but the nitrogen balance remained unaffected. From the present investigation it can be concluded that lactulose and inulin did only partly or scarcely fulfill the expectation of acting as prebiotics in pigs.     

Effects of live yeast on the performance, nutrient digestibility, gastrointestinal microbiota and concentration of volatile fatty acids in weanling pigs

Two experiments were conducted to evaluate the effects of live yeast supplementation on performance, nutrient digestibility, enteric microbial populations and volatile fatty acid (VFA) concentration of weanling pigs, receiving diets supplemented with aureomycin and elevated doses of CuSO4. In experiment 1, 90 crossbred pigs (7.20 +/- 0.44 kg, 28 d of age) were randomly allotted to one of five dietary treatments containing either 0, 4.0 x 10(6), 9.0 x 10(6), 2.6 x 10(7), or 5.1 x 10(7) cfu Saccharomyces cerevisiae per gram with six replicate pens per treatment and three pigs per pen. BWG and feed intake increased quadratically during days 1-14 and days 1-28 as live yeast levels increased (p < 0.01). Pigs fed the diet containing 2.6 x 10(7) cfu yeast per gram had the highest BWG and feed intake among the treatments. In experiment 2, 48 crossbred pigs (7.64 +/- 0.72 kg, 28 d of age) were fed diets containing live yeast at 0 or 3.2 x 10(7) cfu of S. cerevisiae per g with six replicate pens per treatment and four pigs per pen. The yeast supplementation improved BWG and feed intake during days 1-14 (p < 0.01) and days 1-28 (p < 0.05). Treatment differences were not observed in any of the bacterial populations, yeast numbers or VFA concentrations, at any of the sites of the gastrointestinal tract tested. Total tract nutrient digestibility was also not different between treatments. Overall, dietary supplementation of live yeast had a positive effect on BWG and feed intake of weanling pigs, receiving diets supplemented with aureomycin and elevated doses of CuSO4. The improvement in BWG appears to be partly related to an increase in feed intake. The mechanism of yeast improving feed intake of piglets needs to be explored.     

Effects of combined α-galactosidase and xylanase supplementation on nutrient digestibility and growth performance in growing pigs

Two experiments were conducted to investigate the effect of combined supplementation of α-galactosidase and xylanase on nutrient digestibility and growth performance in growing pigs. Experiment 1 had a 2 × 2 Latin square design, where eight barrows (45.0 ± 0.52 kg body weight [BW]) were fitted with a simple T-cannula in the distal ileum and received a basal diet without or with supplementation of α-galactosidase (12 U/kg diet) and xylanase (15 AXC/kg diet) within two periods of 10 d. The apparent ileal digestibility (AID) and apparent total tract digestibility of nutrients, pH, viscosity of digesta and digestive enzyme activities were assessed. In Experiment 2, a total of 432 growing pigs (initial BW 44.7 ± 0.66 kg) were allocated to four treatments. Diets were based on corn and soybean meal and had a normal or reduced nutrient level (reduced by 0.42 kJ digestible energy [DE] per kg and 0.8% crude protein). Both diets were offered without or with supplementation of α-galactosidase and xylanase. The growth performance was assessed within a 43-d feeding period, where at the end, biochemical serum indices were estimated. In Experiment 1, the enzyme-supplemented diet had a greater contents of DE and DE/gross energy ratio (p < 0.05), and a higher AID of Arg, raffinose, stachyose and arabinoxylan (p < 0.05). In Experiment 2, the low nutrient level caused lower daily gain (p < 0.05), which was partially compensated by enzyme addition. Enzyme addition also increased the serum concentration of Lys (p < 0.05). Moreover, it appears that the tested enzyme supplementation could increase dietary DE, serum total amino acid concentrations and decrease serum urea nitrogen.     

Pigs that are divergent in feed efficiency,differ in intestinal enzyme and nutrient transporter gene expression,nutrient digestibility and microbial activity

Feed efficiency is an important trait in the future sustainability of pig production, however, the mechanisms involved are not fully elucidated. The objective of this study was to examine nutrient digestibility, organ weights, select bacterial populations, volatile fatty acids (VFA’s), enzyme and intestinal nutrient transporter gene expression in a pig population divergent in feed efficiency. Male pigs (n=75; initial BW 22.4 kg SEM 2.03 kg) were fed a standard finishing diet for 43 days before slaughter to evaluate feed intake and growth for the purpose of calculating residual feed intake (RFI). Phenotypic RFI was calculated as the residuals from a regression model regressing average daily feed intake (ADFI) on average daily gain (ADG) and midtest BW^0.60 (MBW). On day 115, 16 pigs (85 kg SEM 2.8 kg), designated as high RFI (HRFI) and low RFI (LRFI) were slaughtered and digesta was collected to calculate the coefficient of apparent ileal digestibility (CAID), total tract nutrient digestibility (CATTD), microbial populations and VFA’s. Intestinal tissue was collected to examine intestinal nutrient transporter and enzyme gene expression. The LRFI pigs had lower ADFI (P<0.001), improved feed conversion ratio (P<0.001) and an improved RFI value relative to HRFI pigs (0.19 v. −0.14 SEM 0.08; P<0.001). The LRFI pigs had an increased CAID of gross energy (GE), and an improved CATTD of GE, nitrogen and dry matter compared to HRFI pigs (P<0.05). The LRFI pigs had higher relative gene expression levels of fatty acid binding transporter 2 (FABP2) (P<0.01), the sodium/glucose co-transporter 1 (SGLT1) (P<0.05), the glucose transporter GLUT2 (P<0.10), and the enzyme sucrase–isomaltase (SI) (P<0.05) in the jejunum. The LRFI pigs had increased populations of lactobacillus spp. in the caecum compared with HRFI pigs. In colonic digesta HRFI pigs had increased acetic acid concentrations (P<0.05). Differences in nutrient digestibility, intestinal microbial populations and gene expression levels of intestinal nutrient transporters could contribute to the biological processes responsible for feed efficiency in pigs.     

Effects of corn distillers dried grains with solubles and xylanase on growth performance and digestibility of diet components in broilers

The objective of this study was to investigate the effect of corn distillers dried grains with solubles (cDDGS) and xylanase in corn-based diets on growth performance and digestibility of diet components in broiler chickens. The experiment was a 3×4 factorial design with diets containing 3 levels of cDDGS (0, 100 and 200 g/kg) and 4 levels of xylanase (0, 1200, 2400 and 3600 U/kg). The diets were fed to 720 Cobb 500 chicks for 42 days. Excreta was collected at 18–21 days to measure coefficients of total tract apparent digestibility (CTTAD) and ileal digesta was collected at 42 days to measure coefficients of ileal apparent digestibility (CIAD). Dietary cDDGS caused poor (P<0.05) feed conversion ratio (FCR) of broilers from 1 to 21 and 22 to 42 days, but increased (P<0.05) feed intake (FI) at 1–21 days. Inclusion of xylanase increased (P<0.05) FI by 4–5% at 1–21 days, and did not affect (P≥0.05) FCR in either period. In the two growing periods, cDDGS decreased (P<0.05) the CTTAD of dry matter (DM), and the CIAD of DM and hemicelluloses, whereas xylanase increased (P<0.05) the digestibility of DM and hemicellulose by 5% and 20%, respectively. There were significant interactions (P<0.05) between cDDGS and xylanase for BWG and energy digestibility. In comparison with the 100 g/kg cDDGS diet, the inclusion of 200 g/kg cDDGS led to poorer (P<0.05) FCR at 22–42 days, and lower (P<0.05) CTTAD of DM at 18–21 days. There were no differences (P≥0.05) in most growth parameters between the doses of xylanase at 1200, 2400 and 3600 U/kg. Xylanase at 2400 U/kg increased (P<0.05) CTTAD of DM compared with the lower dose, but 3600 U/kg xylanase showed no further improvement (P≥0.05) on digestibility measurements. The results suggest that supplementing xylanase to diets containing cDDGS can improve growth performance and digestibility of diet components in broilers.     

The nutritional value of narrow-leafed lupine (Lupinus angustifolius) for fattening pigs

The aim of this study was to determine the nutrient digestibility of seeds of four varieties of narrow-leafed lupines (Lupinus angustifolius) and the possibility of soya bean meal (SBM) substitution by lupine seeds alone and in combination with rapeseed meal (RSM) in the diets of pigs. The seeds of the lupine varieties Kalif, Sonet, Zeus and Boruta were analysed. The apparent total tract digestibility (ATTD) was determined on 50 cross-bred pigs using the difference method with titanium dioxide as a marker. The substitution of SBM by lupine seeds alone (at 0 – 100%) was tested on 60 pigs (20–105 kg body weight (BW)) and by a combination of lupine seeds and RSM on 180 fattening pigs (35–80 kg BW). The chemical composition of lupine seeds differed considerably, especially in terms of crude protein and mineral content. All seeds contained less than 0.05% alkaloids and 9.3% oligosaccharides in dry matter. The ATTD of protein ranged from 70% to 74%, those of ether extract from 36% to 55% and those of gross energy from 77% to 84%. The entire replacement of SBM by lupine seeds (var. Sonet) did not have a negative effect on the performance of grower and fattener pigs. The substitution of SBM by a combination of lupines and RSM reduced the performance of growing and finishing pigs significantly.     

Effects of exogenous enzymes on apparent nutrient digestibility in rainbow trout (Oncorhynchus mykiss) fed diets with high inclusion of plant-based protein

Plant-based protein ingredients are increasingly used in feed for carnivorous fish as replacement for fish meal. This study investigated if supplementing diets with high inclusion levels of plant-based protein with three different enzymes could improve the apparent nutrient digestibility in juvenile rainbow trout (Oncorhynchus mykiss). Three diets with high inclusion levels of either de-hulled, solvent extracted soybean meal (344 g/kg), sunflower meal (246 g/kg), or rapeseed meal (264 g/kg) were produced and feed batches were coated post-extrusion with the different enzymes: β-glucanase at 67 mg/kg, xylanase at 208 mg/kg, protease at 228 mg/kg, or a combination of the three enzymes at the same doses. Three consecutive digestibility trials were carried out using a flow-through, modified Guelph System. Each trial was designed to include five dietary treatment groups: a non-supplemented control diet and 4 diets supplemented with either β-glucanase, xylanase, protease or a combination of the three enzymes. Diets were fed to triplicate tanks and two faecal sampling periods for digestibility measurements for each tank were scheduled. Each experiment comprised a 10-day digestibility trial succeeded by a water sampling period for measuring the dissolved nitrogen (N) output. Each experiment lasted 17–19 days in total.Apparent digestibility coefficients (ADCs) of protein, fat, ash, phosphorus and dry matter (DM) were derived from the three digestibility trials, along with calculations of the specific growth rate (SGR, %/d) and feed conversion ratio (FCR). Nitrogen mass-balance and energy retention were evaluated for each dietary treatment group to elucidate on the utilization of digested nutrients and energy.Enzyme supplementation had only moderate effect on apparent nutrient digestibility in the sunflower and rapeseed experiments, while β-glucanase and protease improved the apparent digestibility of all dietary nutrients in the soybean experiment (P<0.05). The effect was more pronounced for lipid than for other nutrients. β-Glucanase had a positive effect on energy retention in the soybean experiment (P<0.05), while there were no effects on nitrogen retention or fish performance in any of the three experiments (P>0.05) during the short feeding periods. The study thus provides preliminary results on the potential of β-glucanase and protease to increase apparent nutrient digestibility of soybean meal in fish feed.     

Effects of increasing the intake of dietary β-glucans by exchanging wheat for barley on nutrient digestibility, nitrogen excretion, intestinal microflora, volatile fatty acid concentration and manure ammonia emissions in finishing pigs

An experiment (complete randomised design) was conducted to investigate the linear and quadratic effects of barley β-glucan inclusion level on total tract nutrient apparent digestibility, nitrogen excretion, intestinal microflora, volatile fatty acid (VFA) profile and manure ammonia emissions in pigs. Twenty-four boars (66 kg) were assigned to one of four treatments: (T1) 0 g/kg barley (control diet) (5.6 g/kg β-glucan), (T2) 222 g/kg barley (12.1 g/kg β-glucan), (T3) 444 g/kg barley (18.9 g/kg β-glucan) and (T4) 666 g/kg barley (25 g/kg β-glucan). Barley was substituted for wheat in the diet. The diets were formulated to contain similar concentrations of digestible energy and digestible lysine. There was a linear decrease (P < 0.001) in the total tract apparent digestibility of dry matter, organic matter, gross energy and neutral-detergent fibre with increasing β-glucan concentration. Faecal nitrogen excretion was affected by dietary β-glucan concentration (quadratic P < 0.05). There was a linear decrease in Enterobacteria concentrations (P < 0.05) with increasing dietary β-glucan concentration. Increasing dietary barley levels caused a linear decrease in colonic (P < 0.01) and caecal pH (P < 0.001). Total caecal VFA and propionic acid were affected by dietary β-glucan concentration (quadratic, P < 0.05). There was a linear decrease in the proportion of acetic acid (P < 0.001), isobutyric acid (P < 0.01) and isovaleric acid (P < 0.05) with increasing levels of dietary barley in both the caecum and colon. There was a linear increase in the proportion of propionic acid (P < 0.001) and butyric acid (P < 0.05) with increasing barley in the colon. In conclusion, high level of dietary β-glucan (25 g/kg) is required to reduce offensive odour forming branched-chain VFAs; however, diet digestibility is compromised at such levels.     

Branched-chain volatile fatty acids and folic acid accelerated the growth of Holstein dairy calves by stimulating nutrient digestion and rumen metabolism

The combined addition of branched-chain volatile fatty acids (BCVFAs) and folic acid (FA) could improve growth performance and nutrient utilization by stimulating ruminal microbial growth and enzyme activity. This study was conducted to evaluate the effects of BCVFA and FA addition on growth performance, ruminal fermentation, nutrient digestibility, microbial enzyme activity, microflora and excretion of urinary purine derivatives (PDs) in calves. Thirty-six Chinese Holstein weaned calves (60 ± 5.4 days of age and 107 ± 4.7 kg of BW) were assigned to one of four groups in a randomized block design. Treatments were control (without additives), FA (with 10 mg FA/kg dietary DM), BCVFA (with 5 g BCVFA/kg dietary DM) and the combined addition of FA and BCVFA (10 mg/kg DM of FA and 5 g/kg DM of BCVFA). Supplements were hand-mixed into the top one-third of total mixed ration. Dietary concentrate to maize silage ratio was 50 : 50 on a DM basis. Dietary BCVFA or FA addition did not affect dry matter intake but increased average daily gain (ADG) and feed conversion efficiency. Ruminal pH and ammonia N were lower, and total volatile fatty acids (VFAs) concentration was higher for BCVFA or FA addition than for control. Dietary BCVFA or FA addition did not affect acetate proportion but decreased propionate proportion and increased acetate to propionate ratio. Total tract digestibility of DM, organic matter, CP and NDF was higher for BCVFA or FA addition than for control. Dietary BCVFA or FA addition increased activity of carboxymethyl cellulase and cellobiase, population of total bacteria, fungi, Ruminococcus albus, R. flavefaciens, Fibrobacter succinogenes and Prevotella ruminicola as well as total PD excretion. Ruminal xylanase, pectinase and protease activity and Butyrivibrio fibrisolvens population were increased by BCVFA addition, whereas population of protozoa and methanogens was increased by FA addition. The BCVFA × FA interaction was significant for acetate to propionate ratio, cellobiase activity and total PD excretion, and these variables increased more with FA addition in diet without BCVFA than in diet with BCVFA. The data indicated that supplementation with BCVFA or FA increased ADG, nutrient digestibility, ruminal total VFA concentration and microbial protein synthesis by stimulating ruminal microbial growth and enzyme activity in calves.     

Effect of excessive dietary fluoride on nutrient digestibility and retention of iron, copper, zinc, and manganese in growing pigs

Ninety-six crossbred growing pigs were used to evaluate the effects of fluoride levels on growth performance, nutrient digestibility, and the retention of minerals in tissues. Four dietary treatments were formulated by supplementing fluorine (as NaF) to a corn-soybean basal diet (39.75 mg/kg F) to provide the following added fluorine levels: 0, 50 100, and 150 mg/kg fluorine. The results showed pigs of the 100 and 150 mg/kg fluorine-added groups had decreased average daily gain (ADG) and increased feed gain ratio (F/G) compared to the control (p<0.05). Apparent digestibility of protein and calcium in 100 and 150 mg/kg fluorinetreated groups was significantly lower than that of the control (p<0.05). On the other hand, iron, copper, zinc, and manganese levels in most tissues of the 100 and 150 mg/kg fluorine groups were markedly changed compared to the control (p<0.05). However, growth performance, nutrient digestibility, and mineral concentrations in all tissues of pigs were not significantly affected by the addition of 50 mg/kg fluorine (p>0.05). Thus, this study suggested that excess fluoride levels could decrease growth performance and change the retention of iron, copper, zinc, and manganese in pigs.     

Effects of graded levels of Fusarium toxin contaminated wheat in diets for fattening pigs on growth performance, nutrient digestibility, deoxynivalenol balance and clinical serum characteristics

A dose response study was carried out with pigs in order to examine the effects of increasing dietary deoxynivalenol (DON)-concentrations on performance, clinical serum characteristics, nutrient digestibility and DON-metabolism. For this purpose, wheat contaminated naturally with Fusarium toxins was incorporated into pig diets at increasing proportions to give calculated dietary DON-concentrations of 0, 2.3 and 4.6 mg/kg during the starter period of phase 1 (14 d) of the experiment, and 0/0, 1.2/1.4, 2.3/3.7 mg/kg starter/grower diet during phase 3 (56 d) of the experiment. Each diet was tested on 16 pigs of both sexes with an initial average live weight of approximately 28 kg. A recovery phase (phase 2, 21 d) was intercalated between phase 1 and 3 of the growth experiment where all groups were fed with the uncontaminated control diet since some pigs exposed to the highest dietary DON-concentration during phase 1 nearly completely refused the offered feed. Affected pigs completely recovered during this phase. In phase 3, when diets with lower DON-concentrations were fed, no differences in performance could be detected. Serum clinical characteristics (enzymes indicating liver damage, total protein, immunoglobulins) did not respond to increasing DON-concentration in the diets. DON-concentration in serum increased in a dose-response-related manner as dietary DON-concentration increased. However, this parameter was not or only weakly correlated to any of the examined performance parameters or serum characteristics. Also, nutrient digestibility of the diets and N-retention were not affected by treatments with the exception of crude fat digestibility which was not consistently influenced. Concentration of DON and its metabolite de-epoxy-DON increased in urine with increasing dietary DON-concentration in a strongly linearly related fashion. The proportion of the excretion of de-epoxy-DON of the total urinary excretion of DON plus de-epoxy-DON rose linearly up to approximately 4%. Total recovery of DON plus de-epoxy-DON as percentage of DON-intake varied between 45 and 57% and was not influenced by dietary DON-concentration. Only a very small fraction of approximately 0.1% of ingested DON was recovered in faeces.     

The effect of high and low dietary crude protein and inulin supplementation on nutrient digestibility, nitrogen excretion, intestinal microflora and manure ammonia emissions from finisher pigs

A 2 × 2 factorial experiment was performed to investigate the interaction between a high- and low-crude-protein (CP) diet (200 v. 140 g/kg) and inulin supplementation (0 v. 12.5 g/kg) on nutrient digestibility, nitrogen (N) excretion, intestinal microflora, volatile fatty acid (VFA) concentration and manure ammonia emissions from 24 boars (n = 6, 74.0 kg live weight). The diets were formulated to contain similar concentrations of digestible energy and lysine. Pigs offered the high-CP diets had a higher excretion of urinary N (P < 0.001), faecal N (P < 0.01) and total N (P < 0.001) than the pigs offered the low-CP diets. Inulin supplementation increased faecal N excretion (P < 0.05) and decreased the urine N : faeces N ratio (P < 0.05) compared with the inulin-free diets. There was no effect (P > 0.05) of dietary treatment on N retention. There was an interaction (P < 0.05) between dietary CP concentration and inulin supplementation on caecal Enterobacteria spp. Pigs offered the diet containing 200 g/kg of CP plus inulin decreased the population of Enterobacteria spp. compared to those with the inulin-supplemented 140 g/kg CP diet. However, CP level had no significant effect on the population of Enterobacteria spp. in the unsupplemented diets. Inulin supplementation increased caecal Bifidobacteria (P < 0.01) compared with the inulin-free diets. There was no effect of inulin supplementation on VFA concentration or intestinal pH (P > 0.05). Pigs offered the 200 g/kg CP diets had higher (P < 0.05) manure ammonia emissions from 0 to 240 h of storage than pigs offered the 140 g/kg CP. In conclusion, inulin supplementation resulted in an increase in Bifidobacteria concentration and a reduction in Enterobacteria spp. at the high CP level indicating that inulin has the ability to beneficially manipulate gut microflora in a proteolytic environment.     

Performance and total-tract digestibility responses to exogenous xylanase and phytase in diets for growing pigs

Sixty individually housed male pigs (Large White X Landrace, average weight 19.7±0.56 kg) were used in a completely randomised block design having five wheat-based dietary treatments (n=12 pigs per treatment) to study the interactive effects between added xylanase (XYL) and phytase (PHY), either alone or in combination, and days on trial on coefficient of total-tract digestibility (CTTAD) and performance. The diets used were: (i) positive control (PC); (ii) negative control with reduced energy and mineral content (NC); (iii) NC with added XYL (NCX); (iv) NC with added PHY (NCP); and (v) NC with added XYL plus PHY (NCXP). The performance response and CTTAD of dietary components were measured 3 and 7 weeks after commencement of feeding, with the experiment finishing when pigs reached approximately 65 kg live weight.Pigs fed the NC diet decreased average daily gain (ADG) by 13% (P<0.01) and increased feed conversion ratio (FCR) by 11% (P<0.01) compared to pigs fed the PC diet. Addition of PHY in the NC diet increased ADG by 9% (P<0.05) and decreased FCR by 5% (P=0.065), whilst addition of XYL in the NC diet had no effect on the performance indices. Combined addition of XYL and PHY in the NC diet did not improve performance of pigs for the first 21 days but improved FCR by 8% (P=0.008) during the days 22–49. Digestibility measurements showed that combined use of XYL and PHY in the NC diet improved CTTAD of dry matter (DM, P<0.05), gross energy (GE, P<0.05) and crude protein (CP, P<0.01) only during the days 22–49. Independent supplementation of PHY in the NC diet tended to improve CTTAD of GE (P=0.09) only during the days 22–49. In contrast, supplementation of PHY immediately improved CTTAD of P and maintained it to similar levels at 49 days. Results suggested that supplementation of PHY plus XYL in combination in the NC diet improved FCR and CTTAD of DM, GE, CP and P but the beneficial effects other than CTTAD of P were derived mainly during days 22–49.     

Efficacy of virginiamycin and a commercially-available lactobacillus probiotic in swine diets

Eight feeding trials using 708 cross-bred pigs were conducted to evaluate the addition of virginiamycin and a commercially-available lactobacillus fermention product (probiotic) to starter, grower and finisher diets based on maize and soya bean meal. Virginiamycin was added at a level of 11 mg/kg of diet, and lactobacillus probiotic at 1 g/kg in starter diets and 500 mg/kg in grower and finisher diets. In the combined analysis of four starter trials, pigs fed on diets containing virginiamycin tended to eat more and grow faster than pigs fed on the control diet, but feed efficiency was not different. Furthermore, daily gain, daily feed intake and feed efficiency were not improved by the addition of lactobacillus probiotic to starter diets. In the combined analysis of a starter—grower—finisher and a grower—finisher trial, virginiamycin supplementation did not alter overall pig performance compared with control. Pigs fed on a positive control diet containing chlortetracycline, penicillin and sulfamethazine had a nonsignificantly greater daily gain and feed intake.Daily gain for the lactobacillus probiotic-fed pigs was lower (P < 0.05) than that of the negative controls, but daily feed intake and feed efficiency were not significantly different. In three growing—finishing trials in which virginiamycin and lactobacillus probiotic were compared in a 2 × 2 factorial arrangement of treatments, daily gain and feed intakes were greater (P < 0.01) for pigs given virginiamycin. The lactobacillus probiotic did not improve daily gain, feed intake or feed efficiency. Overall, no interaction between virginiamycin and lactobacillus probiotic occurred.     

Barley and oat cultivars with diverse carbohydrate composition alter ileal and total tract nutrient digestibility and fermentation metabolites in weaned piglets

An experiment was conducted to evaluate the effects of cereal carbohydrate form (isolated v. cereal matrix) and level, especially mixed-linked β-glucan (hereafter referred to as β-glucan) and starch amylase/amylopectin ratio on nutrient digestibility and fermentation parameters in the intestines of weaned pigs. Four hulless barley cultivars containing varying β-glucan levels (41 to 84 g/kg) were compared with hulled barley, supplemented or not with a β-glucan concentrate (BBG; 270 g/kg β-glucan) and two oat cultivars for digestibility and fermentation metabolites. Seventy-two weaned piglets (BW = 12.8 ± 1.9 kg) were assigned to one of nine diets composed of 815 g/kg cereal, 60 g/kg whey, 90 g/kg soy protein isolate and 35 g/kg minerals. After 15 days, the pigs were killed, and digesta collected from ileum and colon were analyzed for proximate nutrients, short-chain fatty acids (SCFAs), lactic acid (LA) and ammonia. Ileal and total tract digestibility of proximate nutrients and non-starch polysaccharides (NSPs) were determined using HCl-insoluble ash as a marker. Organic matter (OM) ileal digestibility was greater (P < 0.05) for diets based on hulless barley (77% ± 1.1% on average), as compared with hulled barley (64% ± 1.4%) and oat (58% ± 1.5%). Similar trends were found for total tract OM digestibility, varying from 90% ± 0.3% for hulless barley to 67% ± 0.4% for oat, on average. NSP digestibility differed (P < 0.05) within and between cereal types, ranging from 20% (hulled barley plus 163 g/kg BBG or 40 g/kg β-glucan) to 51% (SB94893 hulless barley cultivar with high β-glucan and high amylose ratio) at the ileum and from 44% (hulled barley) to 84% (SB94893 cultivar) at the total tract level. No dietary effect (P > 0.05) was found for SCFA concentration in ileal contents, whereas in colonic contents, SCFA was lower in pigs fed oat (P < 0.001). LA concentration was greater (P < 0.001) in the colon of pigs fed hulless barley than in pigs fed hulled barley and oat. Expressed per kg carbohydrate (NSP + starch) fermented, the ammonia concentration at the colon was lowest for hulled barley diets (supplemented with β-glucan) and the highest for oat diets. In conclusion, the interaction of both form and level of β-glucan impacted nutrient digestibility and fermentation. Hulless barleys with high soluble NSP such as β-glucan and resistant starch yielded, in general higher SCFA and LA and lower ammonia. Hulless barleys may, therefore, have potential for use in feeding strategies designed to improve gut health in pigs.     

Effects of sodium selenite and coated sodium selenite on lactation performance,total tract nutrient digestion and rumen fermentation in Holstein dairy cows

Se can enhance lactation performance by improving nutrient utilization and antioxidant status. However, sodium selenite (SS) can be reduced to non-absorbable elemental Se in the rumen, thereby reducing the intestinal availability of Se. The study investigated the impacts of SS and coated SS (CSS) supplementation on lactation performance, nutrient digestibility, ruminal fermentation and microbiota in dairy cows. Sixty multiparous Holstein dairy cows were blocked by parity, daily milk yield and days in milk and randomly assigned to five treatments: control, SS addition (0.3 mg Se/kg DM as SS addition) or CSS addition (0.1, 0.2 and 0.3 mg Se/kg DM as CSS addition for low CSS (LCSS), medium CSS (MCSS) and high CSS (HCSS), respectively). Experiment period was 110 days with 20 days of adaptation and 90 days of sample collection. Dry matter intake was higher for MCSS and HCSS compared with control. Yields of milk, milk fat and milk protein and feed efficiency were higher for MCSS and HCSS than for control, SS and LCSS. Digestibility of DM and organic matter was highest for CSS addition, followed by SS addition and then control. Digestibility of CP was higher for MCSS and HCSS than for control, SS and LCSS. Higher digestibility of ether extract, NDF and ADF was observed for SS or CSS addition. Ruminal pH decreased with dietary Se addition. Acetate to propionate ratio and ammonia N were lower, and total volatile fatty acids (VFAs) concentration was greater for SS, MCSS and HCSS than control. Ruminal H ion concentration was highest for MCSS and HCSS and lowest for control. Activities of cellobiase, carboxymethyl-cellulase, xylanase and protease and copies of total bacteria, fungi, Ruminococcus flavefaciens, Fibrobacter succinogenes and Ruminococcus amylophilus increased with SS or CSS addition. Activity of α-amylase, copies of protozoa, Ruminococcus albus and Butyrivibrio fibrisolvens and serum glucose, total protein, albumin and glutathione peroxidase were higher for SS, MCSS and HCSS than for control and LCSS. Dietary SS or CSS supplementation elevated blood Se concentration and total antioxidant capacity activity. The data implied that milk yield was elevated due to the increase in total tract nutrient digestibility, total VFA concentration and microorganism population with 0.2 or 0.3 mg Se/kg DM from CSS supplementation in dairy cows. Compared with SS, HCSS addition was more efficient in promoting lactation performance of dairy cows.     

Effects of feeding diets containing essential oils and betaine to heat-stressed growing-finishing pigs

This study was to evaluate the effects of dietary essential oils (EO) and betaine on growth performance, nutrient digestibility and serum hormones in growing-finishing pigs under heat stress conditions. A total of 96 crossed pigs [(Landrace × Yorkshire) × Duroc] with an initial body weight (BW) of 24.7 ± 0.27 kg were used in an 18-week trial. Pigs were randomly allocated to four treatments according to BW and gender. There were six replication pens in each treatment, with four pigs (two barrows and two gilts) per pen. Treatment groups were: (1) control group (CON), basal diet + 23°C for 24 h; (2) heat stress group (HC) with basal diet + 37°C for 9 h, 23°C for 15 h; (3) group HEO, HC with 0.01% EO; (4) group HBE, HC with 0.1% betaine. During the overall period, groups HEO and HBE had higher (p < 0.05) average daily gain than group HC. At week 6, group HC had a lower apparent total tract digestibility (ATTD) of dry matter (DM) (p < 0.05), but at week 12, this group had lower ATTD of DM, nitrogen and gross energy than group HEO (p < 0.05). At week 12 and 18, dietary EO decreased (p < 0.05) serum cortisol and norepinephrine concentration. At week 18, dietary EO and betaine decreased (p < 0.05) epinephrine concentration. Conclusively, dietary EO may be a potential nutritional strategy to alleviate heat stress in growing-finishing pigs.     

Effects of pig genotype (Iberian v. Landrace × Large White) on nutrient digestibility, relative organ weight and small intestine structure at two stages of growth

Although the effects of pig genotype on total-tract apparent digestibility (TTAD) have been widely reported in the literature, there is controversial information on the digestive capacity of indigenous breeds compared with lean-type pigs. The strategy of this study was to test the effects of pig genotype and crude protein (CP) supply on performance, digestive utilization of nutrients, relative organ weight and morphometric analysis of the small intestine. Thirty-eight Iberian (IB) and Landrace × Large White (LD) pigs were used. Three pigs per genotype were slaughtered at approximately 15 kg BW. The remaining pigs were fed one of two diets differing in CP content (13% or 17% as fed) using a pair-fed procedure. Feeding level was restricted at 0.8 × ad libitum of IB pigs. Nutrient digestibility and nitrogen (N) balance trials were performed at 30 and 80 kg BW. Four pigs per dietary treatment and genotype were slaughtered at approximately 50 and 115 kg BW. The gastrointestinal tract and the rest of the visceral organs were weighed and samples of the small intestine were taken to carry out histological and histometrical studies. Daily gain and gain-to-feed ratio were higher in LD than in IB pigs during the fattening and growing-fattening periods (P < 0.01). N TTAD was significantly higher for LD pigs at 30 kg BW (P < 0.05), whereas at 80 kg BW we observed greater values for digestibility of organic matter and energy in IB pigs (averaging 1.5%, P < 0.01). Both N retention (NR) and efficiency of NR were increased in LD pigs at 30 and 80 kg BW (30% as mean value). The proportional weight of the small intestine was greater in LD than in IB pigs at 50 and 115 kg BW. Histometry showed that IB presented a lower muscle layer thickness than LD pigs in ileum, irrespective of the BW (P < 0.05). In contrast, LD pigs showed approximately 10% higher ileal villi length and villi-to-crypt ratio than IB pigs at 115 kg BW. CP supply affected to a larger extent the small intestinal micro-anatomical structure of LD pigs at 50 kg BW. In conclusion, our results suggests that although the higher growth rate, NR and efficiency of NR observed in LD pigs might be associated with presumably more efficient structural aspects of the small intestine, the main differences between the two genotypes should be attributed to a larger extent to protein and energy utilization in tissues with consequences for the overall efficiency of energy use.