Meta-analysis of phosphorus utilization by growing pigs: effect of dietary phosphorus,calcium and exogenous phytase

Optimizing phosphorus (P) utilization in pigs requires improving our capacity to predict the amount of P absorbed and retained, with the main modulating factors taken into account, as well as precisely determining the P requirements of the animals. Given the large amount of published data on P utilization in pigs, a meta-analysis was performed to quantify the impact of the different dietary P forms, calcium (Ca) and exogenous phytases on the digestive and metabolic utilization criteria for dietary P in growing pigs. Accordingly, the amount of phytate P (PP) leading to digestible P (g/kg) was estimated to be 21%, compared with 73% for non-phytate P (NPP) from plant ingredients and 80% for NPP from mineral and animal ingredients (P < 0.001). The increase in total digestible dietary P following the addition of microbial phytase (PhytM) from Aspergillus niger (P < 0.001) was curvilinear and about two times higher than the increase following the addition of plant phytase, which leads to a linear response (P < 0.001). The response of digestible P to PhytM also depends on the amount of substrate, PP (PhytM² × PP, P < 0.001). The digestibility of dietary P decreased with dietary Ca concentration (P < 0.01) independently of phytase but increased with body weight (BW, P < 0.05). Although total digestible dietary P increased linearly with total NPP concentration (P < 0.001), retained P (g/kg), average daily gain (ADG, g/day) and average daily feed intake (ADFI, g/day) increased curvilinearly (P < 0.001). Interestingly, whereas dietary Ca negatively affected P digestibility, the effect of dietary Ca on retained P, ADG and ADFI depended on total dietary NPP (NPP × Ca, P < 0.01, P < 0.05 and P < 0.01, respectively). Increasing dietary Ca reduced retained P, ADG and ADFI at low NPP levels, but at higher NPP concentrations it had no effect on ADG and ADFI despite a positive effect on retained P. Although the curvilinear effect of PhytM on digestible P increased with PP (P < 0.001), this effect was lessened by total NPP for ADG and ADFI (PhytM × NPP and PhytM² × NPP, P < 0.05) and depended on both total NPP and Ca for retained P (PhytM² × NPP × Ca, P < 0.01). This meta-analysis improves our understanding of P utilization, with major modulating factors taken into account. The information generated will be useful for the development of robust models to formulate environmentally friendly diets for growing pigs.     

Effect of phytase supplementation on phosphorus digestibility in low-phytate barley fed to finishing pigs

Forty crossbred barrows (Camborough 15 Line female×Canabred sire) weighing an average of 79.6±8.0?kg were used in a factorial design experiment (5 barleys×2 enzyme levels) conducted to determine the effects of phytase supplementation on nutrient digestibility in low-phytate barleys fed to finishing pigs. The pigs were assigned to one of 10 dietary treatments comprised of a normal 2-rowed, hulled variety of barley (CDC Fleet, 0.26% phytate) or 2 low-phytate hulled genotypes designated as LP422 (0.14% phytate) and LP635 (0.09% phytate). A normal, hulless barley (CDC Dawn, 0.26% phytate) and a hulless genotype designated as LP422H (0.14% phytate) were also included. All barleys were fed with and without phytase (Natuphos 5000 FTU/kg). The diets fed contained 98% barley, 0.5% vitamin premix, 0.5% trace mineral premix, 0.5% NaCl and 0.5% chromic oxide but no supplemental phosphorus. The marked feed was provided for a 7-day acclimatization period, followed by a 3-day faecal collection. In the absence of phytase, phosphorus digestibility increased substantially (P<0.05) as the level of phytate in the barley declined. For the hulled varieties, phosphorus digestibility increased from 12.9% for the normal barley (0.26% phytate) to 35.3 and 39.8% for the two low-phytate genotypes (0.14 and 0.09% phytate respectively). For the hulless varieties, phosphorus digestibility increased from 9.2% for the normal barley (0.26% phytate) to 34.7% for the hulless variety with 54% of the normal level of phytate (0.14% phytate). In contrast, when phytase was added to the diet, there was little difference in phosphorus digestibility between pigs fed normal barley and those fed the low-phytate genotypes (significant barley×enzyme interaction, P=0.01). For the hulled varieties, phosphorus digestibility was 50.1% for the barley with the normal level of phytate (0.26% phytate) compared with 51.1 and 52.4% for the varieties with 54 and 35% of the normal level of phytate (0.14 and 0.09% phytate respectively). For the hulless varieties, phosphorus digestibility increased from 47.1% for the normal barley (0.26% phytate) to 54.4% for the hulless variety with 54% of the normal level of phytate (0.14% phytate). In conclusion, both supplementation with phytase and selection for low-phytate genotypes of barley were successful in increasing the digestibility of phosphorus for pigs. Unfortunately, the effects did not appear to be additive. Whether or not swine producers will choose low-phytate barley or supplementation with phytase as a means to improve phosphorus utilization, will likely depend on the yield potential of low-phytate barley and the additional costs associated with supplementation with phytase.     

Effects of phytase and 25-hydroxyvitamin D3 inclusions on the performance, mineral balance and bone parameters of grower-finisher pigs fed low-phosphorus diets

Two experiments, a performance experiment and a mineral balance study, were conducted on grower-finisher pigs (42 to 101 kg live weight) to investigate the effects of Peniophora lycii phytase enzyme and 25-hydroxyvitamin D3 (25-OHD3) on growth performance, carcass characteristics, nutrient retention and excretion, and bone and blood parameters. The two experiments were designed as a 2 × 2 factorial (two levels of phytase and two levels of 25-OHD3). The four diets were T1, low-phosphorous diet; T2, T1 + phytase; T3, T1 + 25-OHD3 and T4, T1 + phytase + 25-OHD3 diet. In all, 25 μg of 25-OHD3 was used to replace 1000 IU of vitamin D3 in diets T3 and T4. Diets were pelleted (70°C) and formulated to contain similar concentrations of energy (13.8 MJ DE/kg), lysine (9.5 g/kg) and digestible phosphorus (P; 1.8 g/kg). Neither the inclusion of phytase nor 25-OHD3 in the diet had any effect on pig performance. There was an interaction between phytase and 25-OHD3 on calcium (Ca) and P retention (P < 0.01) and on the apparent digestibility of ash (P < 0.01), P (P < 0.001) and Ca (P < 0.001). Pigs offered phytase diets only, had a higher retention of Ca and P and digestibility of ash (P < 0.01), P (P < 0.001) and Ca (P < 0.01) compared with pigs offered unsupplemented diets. However, when the combination of phytase and 25-OHD3 were offered, no effects were detected compared with 25-OHD3 diets only. Pigs fed phytase diets had higher bone ash (P < 0.01), bone P (P < 0.01) and bone Ca (P < 0.05) concentrations compared with pigs offered non-phytase diets. In conclusion, pigs offered phytase diets had a significantly increased bone ash, Ca and P than pigs offered unsupplemented phytase diets. However, there was no advantage to offering a combination of phytase and 25-OHD3 on either bone strength or mineral status compared to offering these feed additives separately.     

Effects of rapeseed meal fiber content on phosphorus and calcium digestibility in growing pigs fed diets without or with microbial phytase

The optimization of dietary phosphorus (P) and calcium (Ca) supply requires a better understanding of the effect of dietary fiber content of co-products on the digestive utilization of minerals. This study was designed to evaluate the effects of dietary fiber content from 00-rapeseed meal (RSM) on P and Ca digestibility throughout the gastrointestinal tract in growing pigs fed diets without or with microbial phytase. In total, 48 castrated male pigs (initial BW=36.1±0.4 kg) were housed in metabolic crates for 29 days. After an 8-day adaptation period, pigs were allocated to one of the eight treatments. The impact of dietary fiber was modulated by adding whole RSM (wRSM), dehulled RSM (dRSM) or dRSM supplemented with 4.5% or 9.0% rapeseed hulls (dRSMh1 and dRSMh2). Diets contained 0 or 500 phytase unit of microbial phytase per kg. From day 14 to day 23, feces and urine were collected separately to determine apparent total tract digestibility (ATTD) and apparent retention (AR) of P and Ca. At the end of the experiment, femurs and digestive contents were sampled. No effect of variables of interest was observed on growth performance. Microbial phytase increased ATTD and AR of P (P<0.001) but the P equivalency with the wRSM diet was lower than expected. Moreover, stomach inorganic P (iP) solubility was improved by microbial phytase (P<0.001). The ATTD of Ca was not affected by microbial phytase which increased AR of Ca and femur characteristics (P<0.05). Ileal recovery of P was not affected by microbial phytase but cecal recovery was considerably reduced by microbial phytase (P<0.001). The decrease in digesta pH between the distal ileum and cecum (7.6 v. 5.9) enhanced the solubility of iP and may have improved its absorption, as supported by the negative relationship between soluble iP and pH (R²=0.40, P<0.001 without microbial phytase and R²=0.24, P=0.026 with microbial phytase). The inclusion of hulls improved the solubility of iP (P<0.05). In conclusion, dehulling does not largely increase nutrient digestibility although dRSM seems to improve the efficacy of microbial phytase in releasing phosphate in the stomach. Moreover, dietary fiber may affect solubilization process in the cecum which potentiates the effect of microbial phytase on P digestibility.     

Meta-analysis of phosphorus utilisation by broilers receiving corn-soyabean meal diets: influence of dietary calcium and microbial phytase

Pollution relative to phosphorus excretion in poultry manure as well as the soaring prices of phosphate, a non-renewable resource, remain of major importance. Thus, a good understanding of bird response regarding dietary phosphorus (P) is a prerequisite to optimise the utilisation of this essential element in broiler diets. A database built from 15 experiments with 203 treatments was used to predict the response of 21-day-old broilers to dietary non-phytate P (NPP), taking into account the main factors of variation, calcium (Ca) and microbial phytase derived from Aspergillus niger, in terms of average daily feed intake (ADFI), average daily gain (ADG), gain to feed (G:F) and tibia ash concentration. All criteria evolve linearly (P < 0.001) and quadratically (P < 0.001) with dietary NPP concentration. Dietary Ca affected the intercept and linear component for ADG (P < 0.01), G:F (P < 0.05) and tibia ash concentration (P < 0.001), whereas for ADFI, it affected only the intercept (P < 0.01). Microbial phytase addition impacted on the intercept, the linear and the quadratic coefficient for ADFI (P < 0.01), ADG (P < 0.001) and G:F (P < 0.05), and on the intercept and the linear component (P < 0.001) for tibia ash concentration. An evaluation of these models was then performed on a database built from 28 experiments and 255 treatments that were not used to perform the models. Results showed that ADFI, ADG and Tibia ash concentration were predicted fairly well (slope and intercept did not deviate from 0 to 1, respectively), whereas this was not the case for G:F. The increase in dietary Ca concentration aggravated P deficiency for all criteria while phytase addition had a positive effect. The more P deficiency was marked, the more the bird response to ADFI, ADG, G:F and tibia ash concentration was exacerbated. It must also be considered that even if the decrease in dietary Ca may improve P utilisation, it could in turn become limiting for bone mineralisation. In conclusion, this meta-analysis provides ways to reduce dietary P in broiler diets without impairing performance, taking into account dietary Ca and microbial phytase.     

Prediction of the amino acid digestibility of legume seeds in growing pigs: a meta-analysis approach

On pig farms, a high proportion of the cost of production comes from feed costs. However, the use of alternative ingredients such as legume seeds may help to reduce this cost. In fact, legume seeds are an important source of essential amino acids (EAA) and can therefore be an alternative to oilseed meals. However, the accurate use of these legume seeds requires a precise knowledge of the standardized ileal digestibility (SID) of EAA, which may vary depending on its botanical variety. A meta-analysis was performed on a database compiling data from 41 studies published between 1981 and 2013 and 178 dietary treatments. Models of prediction of the SID of EAA as well as the dietary concentration of digestible standardized EAA (dEAA) were obtained, based on the chemical composition of ingredients reported in the publications. The effect of the type of legume seeds (faba bean, lupin, pea and soya bean), surgical procedures (T-cannula, re-entrant cannulas, post valve T-cannulas and ileo-rectal anastomosis), and BW of pigs (BW⩽25 kg BW>25 kg) were also tested in each model. Results showed that dietary CP and crude fibre (CF) were, respectively, the best predictors of each EAA SID for faba bean, lupin and pea (R²=0.42 to 0.89) and soya bean (R²=0.32 to 0.77). For the dEAA content, the best prediction models included dietary CP and ADF for faba bean, lupin and pea and soya bean, respectively, with R² ranging from 0.66 to 0.98. Models developed in this study allow predicting the digestibility of EAA in these alternatives feedstuffs.     

Standardized total tract digestible phosphorus requirement of 6 to 13 kg pigs fed diets without or with phytase

Dietary phosphorus concentration greatly affects pig’s growth performance, environmental impact and diet cost. A total of 1080 pigs (initially 5.9 ± 1.08 kg) from three commercial research rooms were used to determine the effects of increasing standardized total tract digestible (STTD) P concentrations in diets without and with phytase on growth performance and percentage bone ash. Pens (10 pigs/pen, 9 pens/treatment) were balanced for equal weights and randomly allotted to 12 treatments. Treatments were arranged in two dose titrations (without or with 2000 units of phytase) with six levels of STTD P each. The STTD P levels were expressed as a percentage of NRC (2012) requirement estimates (% of NRC; 0.45 and 0.40% for phases 1 and 2, respectively) and were: 80%, 90%, 100%, 110%, 125% and 140% of NRC in diets without phytase and 100%, 110%, 125%, 140%, 155% and 170% of NRC in diets with phytase. Diets were provided in three phases, with experimental diets fed during phases 1 (days 0 to 11) and 2 (days 11 to 25), followed by a common diet from days 25 to 46. On day 25, radius samples from one median-weight gilt per pen were collected for analysis of bone ash. During the treatment period, increasing STTD P from 80% to 140% of NRC in diets without phytase improved average daily gain (ADG; quadratic, P < 0.01), average daily feed intake (ADFI; quadratic, P < 0.05) and gain–feed ratio (G : F; linear, P < 0.01). Estimated STTD P requirement in diets without phytase was 117% and 91% of NRC for maximum ADG according to quadratic polynomial (QP) and broken-line linear (BLL) models, respectively, and was 102%, 119% and >140% of NRC for maximum G : F using BLL, broken-line quadratic and linear models, respectively. When diets contained phytase, increasing STTD P from 100% to 170% of NRC improved ADG (quadratic, P < 0.05) and G : F (linear, P < 0.01). Estimated STTD P requirement in diets containing phytase was 138% for maximum ADG (QP), and 147% (QP) and 116% (BLL) of NRC for maximum G : F. Increasing STTD P increased (linear, P < 0.01) the percentage bone ash regardless of phytase addition. When comparing diets containing the same STTD P levels, phytase increased (P < 0.01) ADG, ADFI and G : F. In summary, estimated STTD P requirements varied depending on the response criteria and statistical models and ranged from 91% to >140% of NRC (0.41% to >0.63% of phase 1 diet and 0.36% to >0.56% of phase 2 diet) in diets without phytase, and from 116% to >170% of NRC (0.52% to >0.77% of phase 1 diet and 0.46% to >0.68% of phase 2 diet) for diets containing phytase. Phytase exerted an extra-phosphoric effect on promoting pig’s growth and improved the P dose-responses for ADG and G : F.     

Effect of phytase supplementation on phosphorus digestibility in low-phytate barley fed to finishing pigs

Forty crossbred barrows (Camborough 15 Line female x Canabred sire) weighing an average of 79.6 +/- 8.0 kg were used in a factorial design experiment (5 barleys x 2 enzyme levels) conducted to determine the effects of phytase supplementation on nutrient digestibility in low-phytate barleys fed to finishing pigs. The pigs were assigned to one of 10 dietary treatments comprised of a normal 2-rowed, hulled variety of barley (CDC Fleet, 0.26% phytate) or 2 low-phytate hulled genotypes designated as LP422 (0.14% phytate) and LP635 (0.09% phytate). A normal, hulless barley (CDC Dawn, 0.26% phytate) and a hulless genotype designated as LP422H (0.14% phytate) were also included. All barleys were fed with and without phytase (Natuphos 5000 FTU/kg). The diets fed contained 98% barley, 0.5% vitamin premix, 0.5% trace mineral premix, 0.5% NaCl and 0.5% chromic oxide but no supplemental phosphorus. The marked feed was provided for a 7-day acclimatization period, followed by a 3-day faecal collection. In the absence of phytase, phosphorus digestibility increased substantially (P < 0.05) as the level of phytate in the barley declined. For the hulled varieties, phosphorus digestibility increased from 12.9% for the normal barley (0.26% phytate) to 35.3 and 39.8% for the two low-phytate genotypes (0.14 and 0.09% phytate respectively). For the hulless varieties, phosphorus digestibility increased from 9.2% for the normal barley (0.26% phytate) to 34.7% for the hulless variety with 54% of the normal level of phytate (0.14% phytate). In contrast, when phytase was added to the diet, there was little difference in phosphorus digestibility between pigs fed normal barley and those fed the low-phytate genotypes (significant barley x enzyme interaction, P = 0.01). For the hulled varieties, phosphorus digestibility was 50.1% for the barley with the normal level of phytate (0.26% phytate) compared with 51.1 and 52.4% for the varieties with 54 and 35% of the normal level of phytate (0.14 and 0.09% phytate respectively). For the hulless varieties, phosphorus digestibility increased from 47.1% for the normal barley (0.26% phytate) to 54.4% for the hulless variety with 54% of the normal level of phytate (0.14% phytate). In conclusion, both supplementation with phytase and selection for low-phytate genotypes of barley were successful in increasing the digestibility of phosphorus for pigs. Unfortunately, the effects did not appear to be additive. Whether or not swine producers will choose low-phytate barley or supplementation with phytase as a means to improve phosphorus utilization, will likely depend on the yield potential of low-phytate barley and the additional costs associated with supplementation with phytase.     

Sparing effect of microbial phytase on zinc supplementation in maize-soya-bean meal diets for chickens

The experiment was conducted to evaluate the sparing effect of microbial phytase on the need for dietary zinc supplementation in chicks. A maize–soya-bean meal basal diet, containing 33 mg of zinc and 16 mg of copper per kg, supplemented with 0, 6, 12, 18, 24, 30 or 60 mg of zinc as sulphate per kg or with 250, 500, 750 or 1000 units (FTU) of microbial phytase (3-phytase from Aspergillus niger, Natuphos®) per kg was given to 1-day-old chicks for 20 days. Sixteen chicks placed in individual cages were assigned to each diet except the unsupplemented basal diet which was assigned to 32 cages. Actual range of phytase supplementation was 280 to 850 FTU per kg diet. Growth performance was not affected by microbial phytase. Chicks given the unsupplemented basal diet and the basal diet supplemented with 60 mg of zinc per kg displayed similar performance. Bone weight, bone ash, liver weight and liver dry matter were independent (P > 0.1) of zinc and phytase supplementations. Plasma, bone and liver zinc concentrations increased linearly (P < 0.001) and quadratically (P < 0.001; P < 0.001 and P < 0.05, respectively) with zinc added. Plasma zinc tended to increase linearly (P = 0.07) and bone zinc increased linearly (P < 0.01) with phytase added but no quadratic response was detected (P > 0.1). Liver zinc was unresponsive to phytase added (P > 0.1). Liver copper decreased linearly (P < 0.001) and quadratically (P < 0.01) with zinc supplementation. Mathematical functions were fitted to the responses of plasma and bone zinc to zinc and phytase added and used to calculate zinc equivalency values of phytase. The models included a linear plateau response to zinc added and a linear response to phytase added. In diets without phytase, plasma and bone zinc concentrations were maximised for a dietary zinc concentration of 55 and 51 mg/kg, respectively. Over the range of 280 to 850 FTU, 100 FTU was equivalent to 1 mg of zinc as sulphate. Consequently, in a maize–soya-bean meal chicken diet formulated to contain 60 mg zinc per kg, zinc ingested, and in turn, zinc excreted may be reduced by around 10% if the diet contains 500 FTU as Natuphos® per kg.     

Effect of microbial phytase on apparent ileal amino acid digestibility of phosphorus-adequate diets in growing pigs

Six ileally cannulated pigs (mean initial body weight 34.8 kg) were used to study the effect of microbial phytase on apparent ileal digestibility of P, total N and amino acids. Three P-adequate diets (digestible P concentration 2.3 g kg(- )l) containing barley (B), soyabean meal (S) or a mixture of the two (BS) with or without phytase supplement (1000 FTU x kg(-1)) were fed to pigs using a 6 x 6 Latin square design. The addition of phytase increased (p < 0.05) apparent ileal P digestibility of diets B, S and BS by 16.5, 19.2 and 19.2%, respectively. There was no effect of phytase on the ileal digestibility of total N. Apparent ileal digestibility of amino acids tended to increase in the BS diet supplemented with phytase (mean improvement of 2.2%); but no significant difference was found for any amino acid as compared with the unsupplemented diet. To asses the additivity of apparent amino acid digestibility, the determined values for the BS diet were compared to those calculated from digestibilities found in diets B and S. There were no significant differences between the determined and calculated values. It is concluded that the addition of microbial phytase to P-adequate diets does not affect ileal amino acid digestibility in growing pigs and that the apparent amino acid digestibility values determined in single ingredients may be additive when included into a complex diet.     

Influence of microbial phytase and dietary calcium on the accumulation of lead in different organs of pigs

The objective of this study was to investigate the influence of microbial phytase and calcium supplementation to diets for growing pigs on the retention of lead in the kidney, liver, muscle, brain, and bone (phalanx 1). The experiments were carried out with barrows over the body weight range from 17 to 50 kg. The average lead concentration of the diets was 1.45 mg/kg dry matter. Diets were prepared with or without a supplement of 800 units of microbial phytase. The calcium concentration in the diets was 6.53 or 13.4 g/kg dry matter. The addition of microbial phytase showed an increase of lead concentration in bone. By increasing the calcium concentration to 13.4 g/kg dry matter, it was possible to avoid the phytase-induced increase of lead retention in bone.     

Meta-analysis of the amino acid digestibility of oilseed meal in growing pigs

Oilseed meal is an important source of essential amino acids (EAA) for livestock production. It is the second most important ingredient in pig feed after grains. Optimal use of these ingredients requires precise knowledge of amino acid standardized ileal digestibility (SID), which may vary depending on several factors including botanical variety or processing treatments. A meta-analysis was performed in order to derive models for predicting the SID of soybean, cotton and rapeseed meal EAA, based on chemical composition data such as CP, total concentration of each EAA and fibre (crude fibre, ADF and NDF) content. A database of 47 references (224 experimental treatments) was built. A model incorporating processing method of the meals (e.g. cold pressed, expeller pressed, solvent extracted), experimental surgical procedure (T-cannula, re-entrant cannula, post valve T-cannula and ileo-rectal anastomosis) and pig growth stage (BW⩽ or ⩾25 kg) was tested. Results indicated that neither processing nor BW affected EAA SID. NDF was the best predictor of SID (R²=0.944, 0.836, 0.779, 0.899 and 0.814, respectively, for Lys, Met, Thr, Trp and Val). The total EAA content was the best predictor of digestible content (g/kg diet) for each EAA (R²=0.990, 0.985, 0.977, 0.985 and 0.978, respectively, for Lys, Met, Thr, Trp and Val). This study shows that routine chemical analyses may be used to predict EAA digestibility with satisfactory accuracy.     

the effect of the combination of microbial phytase and amino acid supplementation of diets for finishing pigs on p and n excretion and carcass quality

The objective of this study was to evaluate the effect of a combined low-protein, low-phosphorus diet supplemented with limiting amino acids and microbial phytase on performance, nutrient utilization and carcass characteristics of late-finishing barrows. 4?×?8 crossbreed barrows were continuously housed in metabolism cages from 70?–?110?kg BW and were fed diets, either conventional (A) or protein reduced (B) or protein and phosphorus reduced diets (C) based on barley, maize and soybean meal. Diet A (positive control) contained in air dry matter 13% and 10% CP as well as 0.49% and 0.42% P at growth phases I (70?–?100?kg BW) or II (100?–?110?kg BW), respectively. Diet B was low in CP (11.3%, 8.4%), diet C low in CP and low in P (CP: as B, P: 0.36%, 0.30%). To diet B the limiting amino acids lysine, methionine, threonine and trypthophan were added to meet the levels in diet A. To diet C the limiting amino acids and 800 FTU/kg Aspergillus-phytase were supplemented. At the end of the balance periods the barrows were slaughtered, the carcasses scored and loin chops, ham and Phalanx prima IV were analysed for nutrients and minerals. The CP or P reduction in diets B and C did not generally negatively affect growth, feed efficiency, absolute nitrogen retention or overall carcass performances of the pigs. With the low CP diets B and C, N excretion per unit BWG was decreased by about 23%. The addition of microbial phytase (diet C) increased apparent total tract digestibility of P by about 20%. In spite of 30% reduction of P intake (diet C), the absolute P retention related to 1?kg BW did not differ between treatments. Thus, phytase supplementation in diet C reduced P excretion per unit BWG by about 33%. Phytase raised apparent digestibility of Zn by about 20% but not Ca digestibility. Generally the carcass traits and meat characteristics were not affected by any of the diet strategies. Mineralization of the Phalanx prima IV was also similar in all treatment groups. However, phytase supplementation led to significantly increased zinc concentration in bones (25%). In contrast, Fe incorporation into the Phalanx prima IV was not affected. In general, the feeding regimen introduced in this experiment offers substantial benefits in maintaining a sustainable environmental-friendly pork production even at the stage of late-finishing barrows.     

Effects of Saccharomyces cerevisiae supplementation on ruminal parameters, nutrient digestibility and growth in sheep: A meta-analysis

Despite the increased use of dry active Saccharomyces cerevisiae yeast supplementation in ruminant feeding, inconsistent results among studies hamper the prediction of its effects on animal performance. A meta-analysis has been conducted to quantify the magnitude of yeast supplementation effects on ruminal parameters, total tract nutrient digestibility, growth and feed conversion across different studies with sheep. Different methodologies and small numbers of studies necessitated the use of the classical effect size method, in which a unitless standardised effect size (Hedges's g) was used to calculate differences obtained in outcomes between supplemented and non-supplemented sheep. Summary statistics across studies were calculated with fixed and random effects models, whereas subgroup-analysis and meta-regression were applied to identify possible interfering factors that could be responsible for between-study variability. Possible publication bias was evaluated with graphical and statistical tests. Effect sizes for ruminal ammonia nitrogen (33 comparisons), pH (42 comparisons) and total volatile fatty acids (38 comparison) did not (P > 0.10) present heterogeneity among studies, and was not affected by yeast supplementation. No effects (P > 0.05) were detected on the stoichiometry of volatile fatty acids or protozoa counts. Effects sizes calculated for digestibility of dry matter, organic matter, crude protein, acid-detergent fibre and neutral-detergent fibre, which included from 17 to 28 comparisons, showed considerable (>50%) between-study variability. This variability could not effectively be explained by the categorical variables (1) mode of yeast application, (2) feed intake (ad lib versus restricted) or (3) faeces collection method, or the continuous independent variables (1) adaptation period, (2) study period, (3) dietary roughage concentration and (4) dietary crude protein concentration. According to random effects models, digestibility of dry matter, organic matter and crude protein were increased by yeast supplementation, with no effects found for digestibility of fibre components. Substantial unexplained between-study variability (50–90%) was found for growth (13 comparisons) and feed intake (9 comparisons). This meta-analysis presented evidence that addition of dry active S. cerevisiae yeast to diets did not have any effect on growth, feed conversion, ruminal parameters or fibre digestibility in sheep.     

Evaluation through literature data on standardized ileal digestibility and basal ileal endogenous loss of amino acids associated with barley in pigs

This meta-analysis aimed to estimate the standardized ileal digestibility (SID) and the basal ileal endogenous amino acid losses (IAA_end) in barley for growing pigs. In total, 38 different barley treatments published in 26 peer-reviewed papers were used for the meta-analysis containing information on dietary composition including amino acid (AA) contents of the assay diets, and (or) barley samples, as well as apparent ileal digestibility (AID) of AA in barley. The SID of AA was determined by either correcting AID of AA for their IAA_end or by regression analysis between the apparent ileal digestible and total dietary AA contents. The SID values obtained by correcting the AID values for their IAA_end amounted to 70%, 77%, 74% and 63% for Lys, Met, Thr and Trp, whereas those based on regression analysis method were 82%, 82%, 69% and 55%, respectively. Estimates of basal ileal endogenous loss of CP in ileal digesta varied considerably and averaged 11.84 g/kg dry matter intake (DMI), whereas IAA_end for indispensable AA ranged from 0.05 g/kg DMI for Trp to 1.90 g/kg DMI for Leu. In most cases, these estimates were considerably higher than previously reported values for IAA_end. The results of the present regression analysis indicate for most AA higher SID values compared with SID of most AA that were obtained by correcting AID values for IAA_end. In view of the observed high variations in IAA_end and the low CP content of the barley samples, estimating SID of AA based on literature data by means of the regression method may improve accuracy of SID coefficients for barley. In contrast, transformation of AID values into their corresponding SID values by using a constant correction factor for IAA_end adds an additional source of error, thereby reducing the precision in estimating SID of AA.     

Effects of fibre-degrading enzymes in combination with different fibre sources on ileal and total tract nutrient digestibility and fermentation products in pigs

ABSTRACT

The study was conducted to determine effects of a complex of fibre-degrading enzymes (xylanase, cellulase and β-glucanase) on nutrient digestibility, fibre fermentation and concentrations of short chain fatty acids (SCFA) at different parts of digestive tract in pigs fed different fibre-rich ingredients. A total of 36 barrows fitted with T-cannulas in the distal ileum (initial body weight of 41.1 ± 2.7 kg) were randomly allotted to six dietary treatments with three different high-fibre diets including maize bran (MB), sugar beet pulp (SBP) and soybean hulls (SH) with or without supplementation of fibre-degrading enzymes. Enzyme supplementation improved (p < 0.05) apparent ileal digestibility (AID) of dietary gross energy (GE), crude protein, dry matter (DM), organic matter (OM), total dietary fibre (TDF), neutral detergent fibre (NDF) and apparent total tract digestibility (ATTD) of dietary GE, DM, OM, TDF, insoluble dietary fibre (IDF) when pigs were fed MB, SBP or SH diets. When compared to the SBP and SH diets, the AID of GE, DM, ash, OM and NDF in diet MB was higher (p < 0.05), but the hindgut disappearance and ATTD of nutrients, except for ether extract and crude ash, were lower (p < 0.05). Enzyme supplementation increased acetate and total SCFA concentrations in ileal digesta and faeces of pigs. In conclusion, enzyme addition improved IDF fermentation and SCFA concentration in the whole intestine of pigs, and there was a large variation of digestibility of fibre components among MB, SH and SBP owing to their different fibre composition. Therefore, fibre-degrading enzymes should be applied to fibrous diets to improve efficient production of swine, especially considering low fibre digestibility of fibre-rich ingredients.     

True phosphorus digestibility and the endogenous phosphorus outputs associated with brown rice for weanling pigs measured by the simple linear regression analysis technique

The objectives of this study were to determine true phosphorus (P) digestibility, degradability of phytate-P complex and the endogenous P outputs associated with brown rice feeding in weanling pigs by using the simple linear regression analysis technique. Six barrows with an average initial body weight of 12.5 kg were fitted with a T-cannula and fed six diets according to a 6 × 6 Latin-square design. Six maize starch-based diets, containing six levels of P at 0.80, 1.36, 1.93, 2.49, 3.04, and 3.61 g/kg per kg dry-matter (DM) intake (DMI), were formulated with brown rice. Each experimental period lasted 10 days. After a 7-day adaptation, all faecal samples were collected on days 8 and 9. Ileal digesta samples were collected for a total of 24 h on day 10. The apparent ileal and faecal P digestibility values of brown rice were affected ( P < 0.01) by the P contents in the assay diets. The apparent ileal and faecal P digestibility values increased from − 48.0 to 36.7% and from − 35.6 to 40.0%, respectively, as P content increased from 0.80 to 3.61 g/kg DMI. Linear relationships ( P < 0.05), expressed as g/kg DMI, between the apparent ileal and faecal digestible P and dietary levels of P, suggested that true P digestibility and the endogenous P outputs associated with brown rice feeding could be determined by using the simple regression analysis technique. There were no differences ( P>0.05) in true P digestibility values (57.7 ± 5.4 v. 58.2 ± 5.9%), phytate P degradability (76.4 ± 6.7 v. 79.0 ± 4.4%) and the endogenous P outputs (0.812 ± 0..096 v. 0.725 ± 0.083 g/kg DMI) between the ileal and the faecal levels. The endogenous faecal P output represented 14 and 25% of the National Research Council (1998) recommended daily total and available P requirements in the weanling pig, respectively. About 58% of the total P in brown rice could be digested and absorbed by the weanling pig. Our results suggest that the large intestine of the weanling pigs does not play a significant role in the digestion of P in brown rice. Diet formulation on the basis of total or apparent P digestibility with brown rice may lead to P overfeeding and excessive P excretion in pigs.     

Effect of zinc supplementation from different sources on growth, nutrient digestibility, blood metabolic profile, and immune response of male guinea pigs

Forty weaned male guinea pigs of 208.20±6.62 g mean body weight were divided into 4 groups of 10 animals in a randomized block design. All of the guinea pigs were fed a basal diet [25% ground maize hay, 30% ground maize grain, 22% ground chickpea (Cicer arietinum L.), 9.5% deoiled rice bran, 6% soybean meal, 6% fish meal, 1.45% mineral supplement (without Zn) and 0.05% ascorbic acid] and available green fodder. Group I served as the control (no Zn supplementation), whereas 20 ppm Zn was added in the diet in groups II, III, and IV either as zinc sulfate (ZnSO₄), zinc amino acid complex (ZAAC), and ZnSO₄ ⁺ ZAAC in equal parts, respectively. Experimental feeding lasted for 70 d, including a 3-d digestibility trial. Blood was collected through cardiac puncture from four animals in each group at d 0 and subsequently at the end of experimental feeding. After 40 d of experimental feeding, four animals from each group were injected with 0.4 mL of Brucella abortus cotton strain-19 vaccine to assess the humoral immune response of the animals. After 10 wk of study, four animals from each group were sacrificed to study the concentration of Zn, Cu, Co, Fe, and Mn in the liver, pancreas and spleen. Results revealed no significant difference in the feed intake, body weight gain, and digestibility of the nutrients, except for crude protein (CP) digestibility, which was significantly (p<0.05) lower in group IV. Although concentrations of serum glucose, Ca, and P and the albumin:globulin (A:G) ratio were similar in the different groups, the total protein, albumin, and serum alkaline phosphatase activity were higher in all of the Zn-supplemented groups on d 70. The serum Zn levels at the end of experimental feeding were significantly higher in groups II and III, whereas serum Mn levels were found to be significantly (p<0.05) higher in groups III and IV. The organ weights (as percentage of body weights) did not show any differences among the treatment groups. Although the Mn concentration was significantly (p<0.05) higher in the pancreas, the Cu concentration was significantly (p<0.05) reduced in the spleen in all of the Zn-supplemented groups. The humoral immune response (antibody titer values) on d 14 of vaccination was significantly (p<0.05) higher in all of the Zn-supplemented groups. It was concluded that the 20-ppm level of Zn in the diet might be adequate for growth and nutrient utilization in guinea pigs, but supplementation of 20-ppm zinc significantly improved the immune response and impact was more prominent with the ZAAC (organic source) compared to ZnSO₄ (inorganic source).     

Effect of Ascophyllum nodosum extract on growth performance, digestibility, carcass characteristics and selected intestinal microflora populations of grower–finisher pigs

The effects of an extract of the brown seaweed Ascophyllum nodosum (AN) in grower–finisher pigs are reported. In Experiment 1, the effect of dietary supplementation with increasing levels of AN extract (ANE) on growth performance, carcass characteristics and gastrointestinal microflora was investigated. A total of 360 pigs were randomly allocated, based on initial live-weight and sex, to one of four experimental treatments as follows; control diet (no ANE), control diet plus 3 g ANE/kg, control diet plus 6 g ANE/kg and control diet plus 9 g ANE/kg. These diets were fed ad libitum up to slaughter. In Experiment 2, eight male pigs were allocated to a control diet (no ANE) or the control diet plus 2.5 g ANE/kg to determine effects of ANE on coefficient of total tract apparent digestibility (CTTAD) of nutrients and nitrogen (N) balance. Supplementation with increasing levels of ANE in Experiment 1 resulted in reduced daily gain, carcass weight and kill-out yield during the combined grower–finisher period (P<0.05); however, there were no effects of treatment on feed intake, feed conversion ratio or carcass characteristics. Increasing levels of dietary ANE resulted in decreased ileal coliform counts (P<0.05). Increasing dietary ANE also tended to increase adherent lactobacilli in the colon (P=0.080) but caecal bifidobacteria declined (P<0.05). There were trends towards a linear reduction in colonic bifidobacteria (P=0.077) and towards a quadratic effect on rectal lactobacilli (P=0.077). Intestinal pH was unaffected by ANE supplementation (P>0.05). In Experiment 2, the CTTAD was unaffected by the inclusion of ANE (P>0.05). Overall, the intestinal coliform reductions obtained suggest that ANE may provide a dietary means to improve gut health and potentially reduce pathogen carriage in finishing pigs. However, the negative effects on growth performance observed in healthy animals will most likely limit the commercial use of dietary ANE as a feed additive.     

Effects of deoxynivalenol and sodium meta-bisulphite on nutrient digestibility in growing pigs

ABSTRACT

Deoxynivalenol (DON), a mycotoxin synthesised by the Fusarium, is known to affect the growth of pigs. This effect can be attenuated with sodium meta-bisulphite (SBS). The aim of this study was to evaluate the effect of SBS with antioxidant blend on nutrient digestibility in pigs fed a diet contaminated naturally with DON. Six crossbred castrated pigs fitted surgically with single-T cannulas in the distal ileum received one of four barley-corn-soybean diets with or without SBS. After 8 d of feeding, faeces and ileal digesta were collected for 2 d. Apparent ileal digestibility (AID) of the dry matter (DM), energy, nutrients and DON, and apparent total tract digestibility (ATTD) of DM, acid detergent fibre (ADF), neutral detergent fibre (NDF), energy and DON were evaluated. The AID of phosphorus, calcium and some amino acids was increased (p < 0.05) in the DON diets whereas the ATTD of DM and energy tended to decrease (p = 0.064 and p = 0.071). SBS reduced the AID of DM, energy, ADF, ether extract, phosphorus and DON (p < 0.05) but had no effect on the ATTD of DM, energy, fibre or DON. These results show that DON improved the AID of some nutrients but tended to reduce the ATTD of energy, which could explain, although anorexia is the main effect of DON on live weight gain, the reported negative effect of DON on pig growth. Finally, SBS with antioxidant blend had reduced AID of some nutrients and intestinal absorption of DON.