Prediction models for apparent and standardized total tract digestible phosphorus in swine diets

Prediction models for phosphorus excretion of pigs

OBJECTIVE

The present study aimed to measure fecal and urinary phosphorus (P) excretion from pigs and to develop prediction models for P excretion of pigs.

METHODS

A total of 96 values for P excretions were obtained from pigs of 15 to 93 kg body weight (BW) fed 12 diets in four experiments and were used to develop the prediction models. All experimental diets contained exogenous phytase at 500 phytase units per kg. Body weight of pigs and dietary P concentrations were used as independent variables in the prediction models.

RESULTS

The BW, feed intake, and P intake were positively correlated with total (fecal plus urinary) P excretions (r = 0.80, 0.91, and 0.94, respectively; p<0.001). The models for estimating P excretion were: fecal P excretion (g/d) = -0.654-0.000618×BW2+0.273×BW ×dietary P concentration (R2 = 0.83; p<0.001); urinary P excretion (g/d) = 0.045+ 0.00781×BW×dietary P concentration (R2 = 0.15; p<0.001); total P excretion (g/d) = -0.598-0.000613×BW2+0.280×BW×dietary P concentration (R2 = 0.86; p<0.001) where the BW of pigs and dietary P concentration are expressed as kg and % (as-fed basis), respectively. Based on the developed prediction models, the estimated annual fecal, urinary, and total P excretion for a market pig was 1.24, 0.09, and 1.33 kg/yr, respectively.

CONCLUSION

The P excretions in market pigs can be estimated using BW of pigs and dietary P concentration. In the present model, a market pig excretes 1.24 kg of fecal P and 0.09 kg of urinary P per year.

Digestible calcium equivalency of phytase and nutrient utilization of broiler chickens fed graded levels of limestone or phytase during the starter phase

The current study aimed to quantify the digestible calcium (Ca) equivalency of a new phytase (HiPhorius) in broiler chickens. A total of 1,152 male Cobb 500 broiler chickens were used in an experiment in which 8 diets consisting of graded levels of Ca supplied with limestone or graded levels of the phytase were fed. The 8 dietary treatments were based on a corn-soybean meal diet containing 5.1 g/kg of Ca and 5.1 g/kg of phosphorus (P) as negative control (NC); the NC + 1.3, 2.6, or 3.9 g/kg of Ca from limestone; and the NC + 500, 1,000, 2,000, or 4,000 FYT/kg of phytase. Birds were fed the experimental diets for 3 d (from d 7 to 10) or 14 d (from d 7 to 21) to determine apparent ileal digestibility (AID) and apparent total tract retention (ATTR) of dry matter (DM), CP, Ca, and P. In the 10-day-old birds, increasing the levels of Ca decreased the AID of P and Ca (linear, P < 0.05). Increasing the levels of phytase quadratically improved (P < 0.05) the AID of Ca and P. The AID of DM and CP in the younger birds quadratically increased (P < 0.05) as the levels of Ca increased. There were linear and quadratic effects (P < 0.05) of increasing phytase level for the AID of DM and a linear effect (P < 0.05) for the AID of CP. In the 21-day-old birds, increasing Ca levels resulted in a linear decrease (P < 0.05) in the AID of CP and P, and a quadratic decrease (P < 0.05) in the ATTR of CP. Increasing phytase levels linearly and quadratically (P < 0.05) improved the AID and ATTR of CP, P, and the ATTR of Ca. The analyzed phytase activity in the diets supplemented with phytase ranged from 1,520 to 7,661 FYT/kg. The digestible Ca equivalence for dietary phytase at 1,520 to 7,661 FYT/kg ranged from 1.55 to 2.02 g/kg in the 10-day-old birds fed for 3 d and from 0.52 to 0.64 g/kg in 21-day-old birds fed for 14 d. The results showed the reduction in Ca level that could be accommodated by phytase supplementation, which is markedly different between the younger and older birds. Feeding duration influenced the impact of phytase supplementation on Ca and P digestibility, with better efficacy of phytase observed in the 10-day-old birds fed for 3 d. Also, the results showed the extra-phosphoric effects of phytase on the utilization of other essential nutrients such as protein and Ca.

Phosphorus equivalency of exogenous phytase relative to phosphorus in monosodium phosphate in broiler chickens

The objective of this study was to estimate phosphorus (P) equivalency of exogenous phytase relative to P from monosodium phosphate (MSP) in broiler chickens. To attain this objective, the impact of dietary MSP or exogenous phytase on growth performance, ileal digestibility of P, and bone characteristics in broiler chickens was assessed. Six experimental diets consisting of a P-deficient basal diet based on corn and soybean meal, basal diet plus 0.9 or 1.8 g/kg of inorganic P from MSP, and basal diet plus 500, 1,000, or 2,000 FYT/kg of exogenous phytase. Calcium to P ratio in all diets was maintained at 1.5:1. A total of 576 male broiler chickens (Cobb 500; initial BW = 190 ± 17 g) on d 8 post hatching were allotted to the 6 dietary treatments in a randomized complete block design using BW as a blocking factor. Each dietary treatment contained 8 replicate cages with 12 birds per cage. On d 11 post hatching, 7 birds from each cage were euthanized by CO2 asphyxiation and dissected for the collection of ileal digesta. On d 18, ileal digesta were also collected from the remaining 5 birds in each cage. The left femur and tibia were collected from the bird with the median BW on d 11 and 18 from each cage, and analyzed for bone breaking strength and bone ash. Weight gain and gain-to-feed ratio linearly or quadratically increased (P < 0.05) in every period as the inclusion rate of MSP or phytase increased. Ileal digestibility of P linearly increased (P < 0.05) on d 11 with increasing MSP, but there was no significant effect on d 18. Increasing phytase concentration linearly increased (P < 0.05) ileal digestibility of P on d 11 and 18. Increasing dietary MSP or phytase linearly increased ileal digestible P concentration in diets (P < 0.05). Bone breaking strength and bone ash linearly or quadratically increased (P < 0.05) with increasing inclusion rate of MSP or phytase on d 11 and 18. The equivalency of 1,000 FYT/kg of exogenous phytase based on dietary ileal digestible P concentration was 1.5 and 1.2 g/kg of inorganic P in diets on d 11 and 18, respectively. The current results showed that the supplementation of MSP or exogenous phytase can increase growth performance, ileal P digestibility, bone breaking strength, and bone ash in young broiler chickens.

Effect of Microbial Phytase on Ileal Digestibility of Minerals, Plasma and Urine Metabolites, and Bone Mineral Concentrations in Growing-Finishing Pigs

The study was conducted to evaluate the effects of added phytase in the diet of pigs on utilization of minerals and to determine the essential levels of this supplement in compound feed. An additional aim of the study was a critical assessment of current recommendations regarding the level of phosphorus in the diet of pigs, taking into account the use of phytase. A total of 432 pigs were allotted to six dietary treatments, with nine replicate pens per treatment according to body weight (BW) and sex. The treatments included a negative control (NC) with reduced content of digestible phosphorus; the NC diet supplemented with 6-phytase produced by a genetically modified strain of Aspergillus oryzae in the amount of 250 (NC + 250), 500 (NC + 500), 1000 (NC + 1000), or 1500 (NC + 1500) FTU/kg of feed; and a positive control (PC) diet formulated to meet NCR nutrient requirements for pigs. The results showed that, the higher the phytase activity in the diet (NC+), the lower the concentration of P, Ca, and Mg in the chyme (p < 0.05). Pigs fed the PC and NC+ diets had higher plasma levels of P and Ca than group NC in both fattening periods (p < 0.05). The content of phosphorus in the femur of pigs increased with the level of phytase added to the diet (p < 0.05). The content of Cu and Zn in the femur of pigs in the growing period was higher in groups NC + 500 and NC + 1000 than in the remaining experimental groups (p < 0.001). The content of P and Ca in the feces was higher in pigs fed the PC diet in comparison to the remaining experimental groups in both fattening periods (p < 0.001). There was a decrease in the content of P, Ca, and Mg in the excreta of pigs fed NC+ diets in both fattening periods (p < 0.05). A linear decrease in excretion of zinc in the feces was noted in the case of high levels of phytase, i.e., 1000 and 1500 FTU (p < 0.001). Increasing the level of phytase decreased the Cu (p < 0.001) content in the urine of growing−finishing pigs. In conclusion, the analysis of the effects of the use of phytase in a range of 0−1500 FTU/kg in low-phosphorus diets for fattening pigs indicates that 1000 FTU is the most effective level of phytase for increasing utilization of minerals and reducing excretion of elements into the environment.

Energy concentration and phosphorus digestibility in meat meal, fish meal, and soybean meal fed to pigs

Objective

The objectives of the present study were to determine digestible energy (DE), metabolizable energy (ME), and standardized total tract digestibility (STTD) of phosphorus (P) in meat meal (MM) and to compare these values with those in fish meal (FM), and soybean meal (SBM) fed to pigs.

Methods

Two experiments were conducted to determine energy concentrations and STTD of P in MM, FM, and SBM fed to growing pigs. In Exp. 1, DE and ME in the 3 test ingredients were measured using 24 barrows with initial body weight (BW) of 77.7±8.3 kg. A corn-based diet and 3 diets containing corn and 22% to 30% of each test ingredient were prepared. In Exp. 2, the STTD of P in the 3 test ingredients was measured using 24 barrows (90.9±6.6 kg BW). Three diets were formulated to contain each test ingredient as the sole source of P.

Results

In Exp. 1, the DE and ME values in MM (3,310 and 2,856 kcal/kg dry matter [DM]) were less (p<0.05) than those in FM (4,121 and 3,572 kcal/kg DM) and SBM (4,390 and 4,032 kcal/kg DM). In Exp. 2, FM (64.3%) had greater (p<0.05) STTD of P than SBM (44.8%) with MM (55.8%) having intermediate STTD of P.

Conclusion

The MM contains less energy concentrations compared with FM and SBM, and digestibility of phosphorus in MM does not differ from that in FM and SBM.

Additivity of digestible energy and nutrient concentrations in hatchery byproducts fed to nursery pigs

Objective

The objective was to test additivity of digestible energy and nutrient concentrations in the hatchery byproduct mixture fed to nursery pigs.

Methods

In the previous studies, energy, phosphorus, calcium, and amino acid digestibility of infertile eggs, unhatched eggs, culled chicks, and a mixture of 3 hatchery byproduct ingredients was determined in nursery pigs (initial body weight = 9.4 to 14.2 kg). An additivity test was conducted using these determined values.

Results

No difference was observed between determined and predicted metabolizable energy values in the mixture (3,998 and 3,990 kcal/kg as-is basis, respectively). Measured standardized total tract digestible phosphorus in the mixture was less than the predicted value (4.5 vs 5.3 g/kg as-is basis, respectively; p<0.05). Measured standardized total tract digestible calcium in the mixture was greater compared with the predicted value (40.0 vs 31.7 g/kg as-is basis, respectively; p<0.05). Measured standardized ileal digestible tryptophan in the mixture was greater than the predicted value (3.7 vs 3.1 g/kg as-is basis, respectively; p<0.05) whereas other amino acid values were additive.

Conclusion

Energy and most of amino acid concentrations in hatchery byproducts are additive in the mixture fed to nursery pigs.

Effects of Exogenous 6-Phytase (EC 3.1.3.26) Supplementation on Performance, Calcium and Phosphorous Digestibility, and Bone Mineralisation and Density in Weaned Piglets

Phosphorus (P) is an essential mineral for growing piglets, which is poorly accessible in vegetable feedstuffs as it is stored as phytates. Thus, phytase supplementation is essential to increase P availability. Two experiments were conducted to evaluate a novel 6-phytase (EC 3.1.3.26) in weaned pigs fed low-P diets. In each experiment, one hundred and twenty piglets were fed a positive control (PC; adequate in Ca and P), a negative control (NC; limiting in Ca and P), or NC supplemented with 125, 250, or 500 FTU/kg of phytase (NC125, NC250, and NC500, respectively). P content was lower in diets of Experiment 1 than diets of Experiment 2. In Experiment 1, piglets offered PC or phytase diets had higher growth and efficiency compared with NC diets. In Experiment 2, similar effects were obtained, but the effects were less significant. In both experiments, P and Ca ATTD and bone density were significantly increased with phytase supplementation. Moreover, PC and NC500 had higher P concentrations and lower alkaline phosphatase activity in plasma than NC. To conclude, supplementation with the new 6-phytase at doses up to 500 FTU/kg enhanced P utilization, growth performance, and bone density in piglets fed P-limiting diets.

Prediction equations for digestible and metabolizable energy concentrations in feed ingredients and diets for pigs based on chemical composition

OBJECTIVE

The objectives were to develop prediction equations for digestible energy (DE) and metabolizable energy (ME) of feed ingredients and diets for pigs based on chemical composition and to evaluate the accuracy of the equations using in vivo data.

METHODS

A total of 734 data points from 81 experiments were employed to develop prediction equations for DE and ME in feed ingredients and diets. The CORR procedure of SAS was used to determine correlation coefficients between chemical components and energy concentrations and the REG procedure was used to generate prediction equations. Developed equations were tested for the accuracy according to the regression analysis using in vivo data.

RESULTS

The DE and ME in feed ingredients and diets were most negatively correlated with acid detergent fiber or neutral detergent fiber (NDF; r = -0.46 to r = -0.67; p<0.05). Three prediction equations for feed ingredients reflected in vivo data well as follows: DE = 728+0.76×gross energy (GE)-25.18×NDF (R2 = 0.64); ME = 965+0.66×GE-24.62×NDF (R2 = 0.60); ME = 1,133+0.65×GE-29.05×ash-23.17×NDF (R2 = 0.67).

CONCLUSION

In conclusion, the equations suggested in the current study would predict energy concentration in feed ingredients and diets.

Protein and energy concentrations of meat meal and meat and bone meal fed to pigs based on in vitro assays

The objective of this study was to develop equations for estimating ileal digestible crude protein (CP) and metabolizable energy (ME) contents of meat meal (MM) and meat and bone meal (MBM) as feed ingredients for pigs based on in vitro assays. Test ingredients were 4 sources of MM and 3 sources of MBM. Ash and CP contents of the ingredients ranged from 3.8% to 33.1% and 46.8% to 82.9% (as-is basis), respectively. In vitro ileal disappearance (IVID) of CP was determined and ileal digestible CP content was calculated by multiplying CP content by IVID of CP. In vitro total tract disappearance (IVTTD) of dry matter (DM) was determined and ME was calculated using gross energy, CP contents, and IVTTD of DM. The IVID of CP and IVTTD of DM ranged from 77.2% to 88.7% and from 82.7% to 92.4%, respectively. Calculated ileal digestible CP and ME contents ranged from 37.8% to 73.5% DM and 2,405 to 3,905 kcal/kg DM, respectively. Ash contents were negatively correlated (P < 0.001) with CP (r = −0.99), in vitro ileal digestible CP (r = −0.97), gross energy (r = −1.00), in vitro digestible energy (r = −0.97), and adjusted ME (r = −0.97). The most fitting equations for ileal digestible CP and adjusted ME were: ileal digestible CP (% DM) = 11.91 − 0.90 × Ash (% DM) + 0.74 × IVID of CP (%) (R² = 0.99) and adjusted ME (kcal/kg DM) = 130.85 − 50.90 × ash (% DM) + 47.06 × IVTTD of DM (%) (R² = 0.99). To validate the accuracy of the prediction equations for ME, mean bias and linear bias were determined using a regression analysis. Calculated ME values of MM and MBM were in a good agreement with data obtained from animal experiments based on a statistically insignificant bias in the models. In conclusion, ME concentrations of MM and MBM as swine feed ingredients can be calculated using ash concentration and in vitro disappearance of dry matter.