Zur Messung der Verdaulichkeit des Phosphors aus mineralischen Phosphor-Trägern sowie aus Mineralfuttern, Eiweißkonzentraten und Alleinfuttern für Schweine

Novel procedure for estimating endogenous losses and measurement of apparent and true digestibility of phosphorus by growing pigs

An experiment was conducted to evaluate a novel procedure for estimating endogenous losses of P and for measuring the apparent total tract digestibility (ATTD) and true total tract digestibility (TTTD) of P in 5 inorganic P sources fed to growing pigs. The P sources were dicalcium phosphate (DCP), monocalcium phosphate (MCP) with 50% purity (MCP50), MCP with 70% purity (MCP70), MCP with 100% purity (MCP100), and monosodium phosphate (MSP). A gelatin-based, P-free basal diet was formulated and used to estimate endogenous losses of P. Five P-containing diets were formulated by adding 0.20% total P from each of the inorganic P sources to the basal diet. A seventh diet was formulated by adding 0.16% P from MCP70 to the basal diet. All diets were fed to 7 growing pigs in a 7 x 7 Latin square design, and urine and feces were collected during 5 d of each period. The endogenous loss of P was estimated as 139 +/- 18 mg/kg of DMI. The ATTD of P in MSP was greater (P < 0.05) than in DCP, MCP50, and MCP70 (91.9 vs. 81.5, 82.6, and 81.7%, respectively). In MSP, the TTTD of P was 98.2%. This value was greater (P < 0.05) than the TTTD of P in DCP, MCP50, and MCP70 (88.4, 89.5, and 88.6%, respectively). The ATTD and the TTTD for MCP70 were similar in diets formulated to contain 0.16 and 0.20% total P. Results from the current experiment demonstrate that a P-free diet may be used to measure endogenous losses of P in pigs. By adding inorganic P sources to this diet, the ATTD of P can be directly measured and the TTTD of P may be calculated for each source of P.

Investigations on the availability of inorganic phosphate from different sources with growing White Pekin ducks

Methodological aspects of determination of P availability in ducks were addressed in this study. Three balance experiments with quantitative excreta collection were performed with growing male White Pekin ducks that were 3 wk of age. When P from monobasic calcium phosphate (MCP) was added in graded levels below the requirement to a low-P basal diet, ducks responded nonlinearly in P accretion. With increases in dietary Ca:P ratio from 1.2:1 to 1.6:1 to 2.0:1, ymax in P accretion increased from 0.91 to 0.97 to 1.03 g/duck during the 5-d period of measurement, and marginal efficiency of utilization (deltay/deltax) of P from MCP increased from 75 to 85 to 91%. The overall utilization of plant P from the low-P basal diet was adversely affected by increasing dietary Ca:P ratio and decreased from 49 to 45 to 40%. Seven inorganic P sources were supplemented to a low-P basal diet to increase P content by 0.9 or 1.9 g/kg. Utilization of P from the sources was lower at 1.9 g/kg compared with at 0.9 g/kg, although supply was still below requirement, indicating that ducks fed 1.9 g/ kg were in the diminishing part of the response curve. Thus, only the values determined at the low level of supplementation were considered as a measure of availability. P availabilities were 100% for monosodium phosphate, 96% for anhydrous dibasic calcium phosphate, 92% for calcium sodium magnesium phosphate, 91% for monodibasic calcium phosphate, 86% for 2 batches of dihydrated dibasic calcium phosphate, and 77% for calcium sodium phosphate. It was concluded that availability studies aiming to characterize the capacity of an ingredient require standardization with regard to the level of P supply and the dietary Ca:P ratio. Similar to results from other species, the availability of inorganic feed phosphates for ducks is on an overall high level, but differences between P sources should be considered in diet formulation.

Response of growing Pekin ducks to supplementation of monobasic calcium phosphate to low-phosphorus diets

The effects of a supplementation of P from monobasic calcium phosphate (MCP; Ca(H2PO4)2) to low-P basal diets were studied in growing Pekin ducks. Body weight gain and feed conversion were studied in two separate periods between Days 1 to 21 (Experiment 1) and between Days 21 to 49 (Experiments 2 and 3). Retention of P was measured by comparative slaughter technique in Experiment 1. Additionally, two balance trials with quantitative determination of intake and excretion of P were conducted between Days 12 to 17 and between Days 30 to 35. MCP was supplemented in 7 or 6 graded levels at the expense of sand. In cases when ANOVA showed a significant effect of MCP supplementation, the response of ducks was described by nonlinear functions. No significant effect of supplemental MCP on growth, feed intake or feed/gain ratio was detected in the period between Days 21 and 49 with a basal P level of 3.0 g/kg. Between Days 1 and 21, ducks needed 5.1 g P/kg diet to achieve 95% of ymax in BW gain. The ymax for P concentration in gained BW, determined from balance trials, was 5.6 and 5.1 g/kg between Days 12 to 17 and Days 30 to 35, respectively. Ninety-five percent of ymax in P retention was achieved with a dietary P concentration of 6.2 and 4.3 g/kg between Days 12 to 17 and Days 30 to 35. The cumulative efficiency of utilization (retention/intake x 100) of dietary P from the basal diet was 49% (Days 12 to 17) and 43% (Days 30 to 35), and approached maximum with increasing supplementation of MCP of 55 and 53%, respectively, before it decreased again with further increase in MCP supplementation. The marginal efficiency of supplemental P (deltay/deltax) showed a maximum of 86% (Days 12 to 17) and 92% (Days 30 to 35), and this maximum was achieved where only 75 and 72% of ymax in P retentions were achieved. It is concluded that ducks require a lower P concentration in the diet with increase in age, but that the efficiency of utilization of P from inorganic salts is not clearly affected by age. Conclusions regarding the P requirement largely depend on the response criterion chosen. Based on P retention data, a dietary level of available P is recommended to be 3.4 (Days 1 to 21) and 2.3 g/kg (Days 21 to 49), although growth was unaffected by P even at lower concentrations of available P. Future comparative studies on the availability of P from ingredients should be conducted at a dietary P concentration that allows for identifying the maximum in utilization.

Consequences of the ban of by-products from terrestrial animals in livestock feeding in Germany and the European Union: alternatives, nutrient and energy cycles, plant production, and economic aspects

Consequences of the ban of meat and bone meal (MBM) and animal fat with regard to livestock feeding, cropping, ecology and economy where investigated with an inter-disciplinary approach for Germany and the European Union. Calculations were made for different production systems with pigs and poultry on the basis of statistical data for the production and for the feed markets as well as from requirement data for the respective species and production system. (1.) The ban of MBM from feeding caused a need for alternative protein sources. If all the amount of protein from MBM is to be replaced by soybean meal, in Germany and the EU about 0.30 and 2.30 x 10(6) t would be needed each year (supplementary amino acids not considered). Alternatively, doubling the grain legume acreage in Germany to about 420,000 ha would supply a similar amount of protein. A wider application of phase feeding with adjusted dietary amino acid concentrations, however, would allow for saving protein to an extent which is similar to the amount of protein that was contributed by MBM in recent years. Thus, the ban is a minor problem in terms of ensuring amino acid supply. (2.) However, alternative plant ingredients cannot compensate for the gap in P supply that is caused by the ban. An additional demand for inorganic feed phosphates of about 14,000 and 110,000 t per year is given in Germany and the EU, respectively. So far, this gap is filled almost completely by increased mining of rock phosphates. Alternatively, a general application of microbial phytase to all diets would largely fill this gap. Until the ban, MBM contributed to 57% of the supplementation of P that was needed for pigs and poultry. The ban of MBM makes large amounts of P irreversibly disappearing from the food chain. (3.) Energy from slaughter offal and cadavers can be utilized in different technologies, in the course of which the efficiency of energy utilisation depends on the technology applied. It is efficient in the cement work or rotation furnace if heat is the main energy required. In contrast, the energetic efficiency of fermentation is low. (4.) Incineration or co-incineration of MBM and other by-products causes pollution gas emissions amounting to about 1.4 kg CO2 and 0.2 kg NOx per kg. The CO2 production as such is hardly disadvantageous, because heat and electrical energy can be generated by the combustion process. The prevention of dangerous gaseous emissions from MBM burning is current standard in the incineration plants in Germany and does not affect the environment inadmissibly. (5.) The effects of the MBM ban on the price for compound feed is not very significant. Obviously, substitution possibilities between different feed ingredients helped to exchange MBM without large price distortions. However, with each kg MBM not used in pig and poultry feeding economic losses of about 0.14 [symbol: see text] have to considered. In conclusion, the by far highest proportion of raw materials for MBM comes as by-products from the slaughter process. Coming this way, and assuring that further treatment is safe from the hygienic point of view, MBM and animal fat can be regarded as valuable sources of amino acids, minerals and energy in feeding pigs and poultry. Using them as feedstuffs could considerably contribute to the goal of keeping limited nutrients, phosphorus in particular, within the nutrient cycle and dealing responsible with limited resources.

The course of phosphorus excretion in growing pigs fed continuously increasing phosphorus concentrations after a phosphorus depletion

A balance study was performed in order to quantify the effect of continuously increased phosphorus (P) intake on faecal and urinary P excretion. The aim was to quantify the level of intake where regulatory P excretion becomes relevant for comparative digestibility measurements on P, and when the pig adapts its urinary P excretion to increased P intake. Phosphorus intake of growing pigs was continuously increased on a daily basis starting at a marginal level and P excretion via faeces and urine was continuously followed for 92 days. Two semi-synthetic diets were prepared with different proportions of Na2HPO4 resulting in 2.4 (diet 1) and 6.3 (diet 2) g P/kg DM. Concentration of Ca was adapted to achieve a Ca supply approximately 3.1 fold the digestible P supply. Six castrated male crossbred pigs (31 kg BW) were kept individually in metabolism crates after they had undergone a 14 d P depletion period during which they were fed diet 1 solely. Pigs received 1.04kg of diet 1 per day throughout the experiment, and each day the amount of feed and P supplied to pigs from diet 2 was increased by 12 g and 69 mg, respectively. ME supply was approximately 2.4 fold maintenance and average daily BW gain of pigs during the entire experiment was 690 +/- 30 g. While intake increased linearly, faecal excretion of P and Ca increased non-linearly and could be best described by third order polynomial functions. The proportion of ingested P not excreted via faeces followed a quadratic type of curve with a maximum of 81% at 25 days on experiment and P intake of 4.0 g/d. Thereafter, the proportion decreased continuously. The digestibility of P from diet 2, determined by the slope ratio technique, was constant and not affected by P intake up to a P intake of 5 g/d. Renal P excretion did not exceed inevitable losses until day 60 and increased exponentially thereafter when body P reserves were restored. It is concluded, that an adaptation to surplus P supply occurred earlier on the intestinal than on the renal level. While faecal P excretion appeared regulated depending on the actual requirement for P retention, the regulation via urine depended on the P status of the pig. Once the renal P excretion of growing pigs exceeds a level of 25 mg/d, intake of digestible P cannot be regarded sufficiently low to measure P digestibility as a capacity of the feedstuff.

Effect of body weight on phosphorus digestibility and efficacy of a microbial phytase in young pigs

The effect of body weight on P digestibility and on efficacy of supplemental Aspergillus niger phytase was studied in two experiments with young growing pigs. Excreta were collected quantitatively. All diets contained 2.0 g digestible P per kg dry matter at a maximum and renal P excretion never exceeded 15 mg/d. When dietary P mainly originated from monocalcium-phosphate, both P digestibility and Ca net absorption linearly increased by 3.6 and 5.6 percentage units, respectively, when BW increased from 15 to 35 kg. With a similar range in BW, P digestibility and Ca net absorption were unaffected by BW when P mainly originated from maize, barley and soybean meal. In both types of diet, crude protein digestibility increased with increasing body weight, whereas organic matter digestibility was effected by BW only in the diet containing maize, barley and soybean meal. Phytase (400 U/kg) almost doubled P digestibility when supplemented to a diet with P mainly originating from maize, soybean meal and barley. This effect of phytase supplementation was equal in pigs at 15.7 kg BW (33 vs. 55%) and at 39.1 kg BW (32 vs. 56%). Digestibility of any organic fraction was unaffected by supplemental phytase. With regard to on-farm conditions, it appears eligible from this results to apply digestibility coefficients for P determined in growing-finishing pigs for piglets as well.

Inevitable losses of phosphorus in pigs, estimated from balance data using diets deficient in phosphorus

Faecal losses of phosphorus (P) were determined in 66 growing pigs weighing between 30 and 70 kg on a semi-purified diet containing less than 1.3 g P/kg DM. Regression analysis showed that the coefficient of absorption of P from this diet was 82.5% and that inevitable faecal P excretion of pigs fed this diet was, on average, 5.9 mg/kg BW.d-1 with no statistically significant effect of body weight on faecal P excretion within the range of body weight studied. Semi-purified diets almost identical in composition were also fed to 5 piglets weighing about 20 kg and to 4 heavy pigs of about 150 kg BW. Inevitable daily faecal losses of P were calculated to be 6.2 mg/kg BW in piglets and 6.8 mg/kg BW in the heavy pigs. It is concluded that inevitable faecal losses of P do depend on body weight and that the variation faecal P excretion was too great to allow detecting this effect within the limited range between 30 and 70 kg BW. Further diets were obtained by blending various ingredients into the semi-purified diet. From a total of 262 balances measured under the condition of suboptimal P supply it is concluded that daily inevitable urinary losses of P depend on body weight and, on average, amount to 0.35 mg/kg BW. It is concluded that under the conditions of suboptimal P supply the utilisation of digestible P is almost complete.

Digestibility of phosphorus in protein-rich ingredients for pig diets

Two experiments were run to determine the digestibility of phosphorus in different vegetable and animal proteins for the pig diet. Each experiment comprised two 4 x 4 Latin squares run concurrently. Pigs initially weighing 30 kg were kept in metabolism crates and fed twice daily at about 2.5-fold metabolisable energy requirement for maintenance. A semi-purified basal diet low in phosphorus and without intrinsic phytase activity was fed either alone or after blending into mixtures with one of the ingredients to be tested. Mixtures were calculated to contain not more than 2 g digestible P/kg DM and between 5.0 and 6.0 g Ca/kg DM. Faeces and urine were quantitatively collected for 8 days after 7 days of adaptation. Phosphorus digestibility for ingredients under test was calculated assuming the digestibility of phosphorus from the basal diets to be constant in all diets. P digestibilities in solvent extracted soybean meal from dehulled seed, rapeseed and solvent extracted rapeseed meal were 37, 42 and 24%, respectively. Supplementation of a microbial phytase (750 U/kg diet) improved digestibility coefficients significantly to 76, 66 and 73%, respectively. Digestibility of phosphorus in 3 different batches of fish meal ranged from 85 to 90%, without significant differences between batches. In 3 different types of carcass meal, digestibility coefficients were 80, 82 and 83% without significant differences between types, and digestibility of phosphorus from bone meal was 80%.