A METHOD FOR IMPROVING THE NUTRITIONAL VALUE OF ANIMAL FEED

Abstract

Offering broiler chickens a low protein diet supplemented with an array of synthetic amino acids is not fully effective in promoting maximal growth and both bodyweight and feed conversion ratio (FCR). However the present invention shows, growth rate and FCR can be promoted by the addition of available Phosphorus to the low protein diet and that this strategy is effective in restoring performance losses associated with the diet with low protein concentration. Therefore, the present invention relates to a method for improving the nutritional value of animal feed comprising a marginal protein content. More specifically, the invention relates to a method for improving weight gain and feed conversion ratio, which method comprises feeding the animal with a low protein diet and an extra supplementation of phosphorous.

Claims

1. A method of improving nitrogen utilization in an animal, the method comprising the steps of administering an animal feed composition comprising a low protein diet and an available phosphorous concentration to said animal, wherein said low protein diet contains at least 5% less crude protein than a standard protein diet for optimal growth performance of the target animal species and wherein the concentration of available phosphorous associated with enhanced animal performance is higher in said animal feed compared to an animal feed comprising a standard protein diet.

2. A method of improving weight gain and/or feed conversion ratio in an animal, the method comprising the steps of administering an animal feed composition comprising a low protein diet and an available phosphorous concentration to said animal, wherein said low protein diet contains at least 5% less crude protein than a standard protein diet for optimal growth performance of the target animal species and wherein the concentration of available phosphorous associated with enhanced animal performance is higher in said animal feed compared to an animal feed comprising a standard protein diet.

3. A method according to claim 1, wherein the low protein diet contains at least 30%, at least 25%, at least 20%, at least 15%, or at least 10% less crude protein than the standard diet of the target animal species.

4. A method according to claim 1 wherein the increase of available phosphorous concentration in the diet is achieved by a. increasing the dietary concentration of inorganic phosphate, b. additional supplementation of exogenous enzymes, c. through alternative interventions such as, but not limited to, acidification of drinking water, reduction in the concentration of dietary cations or through the use of intermittent lighting programs or feeding of whole-grain cereals to enhance gastric gut development.

5. Method according to claim 4, wherein the increase of available phosphorous concentration in the diet is achieved by additional supplementation of at least one inorganic phosphate selected from the group consisting of monocalcium phosphate, dicalcium phosphate, defluorinated phosphate.

6. Method according to claim 4, wherein the increase of available phosphorous concentration in the diet is achieved by additional supplementation of at least one exogenous enzyme selected from the group consisting of phytase, protease, carbohydrase.

7. Method according to claim 6, wherein a supplemental phytase at inclusion concentrations of at least 5000 FYT/kg, at least 4000 FYT/kg, at least 3000 FYT/kg, at least 2000 FYT/kg, at least 1000 FYT/kg or at least 500 FYT/kg is used.

8. The method according to claim 1, wherein the phytase is classified as belonging to the EC 3.1.3.26 group.

9. The method according to claim 1, wherein the protease is an acid stable serine proteases obtained or obtainable from the order Actinomycetales.

10. The method according to claim 9, wherein the protease is an acid stable serine protease derived from Nocardiopsis dassonvillei subsp. dassonvillei DSM 43235 (A1918L1), Nocardiopsis prasina DSM 15649 (NN018335L1), Nocardiopsis prasina (previously alba) DSM 14010 (NN18140L1), Nocardiopsis sp. DSM 16424 (NN018704L2), Nocardiopsis alkaliphila DSM 44657 (NN019340L2) and Nocardiopsis lucentensis DSM 44048 (NN019002L2), as well as homologous proteases.

11. The method according to claim 1, wherein the animal is selected from poultry, pigs and cattle.

12. Use of an additional supplementation of inorganic phosphate in animal feed for improving weight gain and/or feed conversion, the digestibility of proteins and/or the assimilation of amino acids and/or nitrogen in animals and/or to increase total energy levels in animal feedstuff.

13. Use of an additional supplementation of exogenous phytase in animal feed for improving weight gain and/or feed conversion, the digestibility of proteins and/or the assimilation of amino acids and/or nitrogen in animals and/or to increase total energy levels in animal feedstuff.

14. Use according to claim 12, wherein said animal feed is characterized by a low protein diet containing at least 5% less crude protein than a standard protein diet for optimal growth performance of the target animal species.

15. Use according to claim 14, wherein the low protein diet contains at least 30%, at least 25%, at least 20%, at least 15%, or at least 10% less crude protein than the standard diet of the target animal species.

16. Use according to claim 12, wherein the animal is selected from poultry, pigs and cattle.

Description

EXAMPLE: ANIMAL TRIAL

Summary

[0062] A total of 945 male Ross 308 broiler chicks were used in a growth study to explore the interaction between dietary crude protein concentration and available phosphorus. Nine experimental treatments were constructed factorially by offering low, medium or standard protein concentrations without or with low, standard or high available phosphorus. Diets were based on corn, wheat and soybean meal and all nutrients other than protein/amino acids and available phosphorus were maintained at or above breeder guidelines. Additional synthetic amino acids were used in the diets with low protein concentration in attempt to maintain digestible amino acid supply. Diets were offered to 7 replicate pens of 15 chicks per pen from d8 to 35. Growth performance was measured during the grower (d8-24) and finisher (d25-35) periods. On d35 carcass composition was determined, blood was drawn for various biochemical measurements and the tibia was excised for mechanical and compositional analyses. Birds that received the low protein diet had lower terminal bodyweight and poorer feed conversion ratio compared with those that received diets with adequate crude protein content. However, addition of available phosphorus to the low protein diet resulted in significant reductions in weight-corrected feed conversion that were not evident in the diet with standard protein content. Bone architecture was only moderately influenced by dietary treatment but birds that ingested the low protein diets had relatively heavier abdominal fat pad weight. Blood biochemistry was influenced by both dietary protein and available phosphorus and trends suggested that both axes are involved in protein accretion and catabolism. It can be concluded that performance losses associated with feeding low protein diets to broiler chickens may be partially restored by additional available phosphorus. The implications for use of exogenous enzymes such as protease and phytase and protein nutrition per se warrants further examination.

[0063] Materials and Methods

[0064] Birds and Diets

[0065] The study procedures were reviewed and approved by the University of New England Animal Ethics Committee to ensure compliance with welfare and humane practices.

[0066] A total of 990 off-sex male broiler chickens (Ross 308) were obtained from a local hatchery (Aviagen, Goulburn, NSW, Australia). All chicks were offered a common starter diet formulated to meet or exceed Ross 308 nutrient specifications (Aviagen, 2014) with an apparent metabolizable energy (AME) content of 3,000 kcal/kg, 1.28% digestible lysine, 0.90% calcium (Ca) and 0.45% available P. On d8, 945 healthy chicks were weighed and distributed to 63 floor pens, 15 chicks per pen, to achieve an equivalent pen weight (+/−50 g/pen). A total of 9 dietary treatments were generated by factorially arranging 3 concentrations of crude protein (21.5/19.5%, 19.5/17.5% or 17.5/15.5%; grower/finisher respectively) and 3 concentrations of available P (0.48/0.45%, 0.43/0.40% or 0.38/0.35%; grower/finisher respectively). Chicks were raised in a windowless and environmentally controlled house. The ambient temperature was initially set and maintained at 33±1.0° C. for the first three days upon chick's arrival and then gradually decreased by 1.0° C. every 2 days to reach 23.0° C. and kept constant thereafter to the end of the trial. Lighting and ventilation program followed the recommendations set forth in the Ross 308 breed management manual. Feed and water were available throughout the experiment ad libitum.

[0067] Diets were based on corn, wheat and SBM (Tables 1-4) and were formulated to be equivalent in all nutrients other than those that were the focus of the experiment. Digestible amino acids were added in increasing concentrations as dietary crude protein was reduced to ensure essential amino acid requirements were met, even at the lowest protein level. Dietary electrolyte balance an K provision was maintained as SBM was displaced by addition of K carbonate.

[0068] Measurements

[0069] Bodyweight gain and feed consumption were measured and FCR calculated for the grower (d8-24) and finisher (d25-35) periods and over the entire experimental period (d8-35). Mortality, on a pen basis, was used to correct FCR values. On d35 bodyweight corrected FCR (FCRc) was also calculated and presented as there were treatment-associated differences in bodyweight. This correction was achieved by consider a 30 g difference in bodyweight was equivalent to 1 point in FCR.

[0070] On d35, a total of 3 birds per pen were selected at random, electrically stunned and euthanized. Blood samples were individually collected in none-heparinized tubes from the jugular vein of two birds. Skinless breast meat, thigh+drumstick, and abdominal fat pad were removed, weighed and calculated as a percentage of live body weight. Tibia samples were also collected for breaking strength test and mineral composition analysis. The digesta content of the ileum (portion of the small intestine from Meckel's diverticulum to approximately 1 cm proximal to the ileocecal junction) were gently squeezed out and pooled per replicate pen, to determine digesta dry matter and water content.

[0071] Chemical Analysis

[0072] The nitrogen (N) content of feed samples, in duplicate, were determined from a 0.25-g sample in a combustion analyzer (Leco model FP-2000 N analyzer, Leco Corp., St. Joseph, Mich.) using EDTA as a calibration standard, with crude protein being calculated by multiplying percentage N by a correction factor (6.25). All diets (in duplicate) were analyzed for total N, and mineral profile (Table 5).

[0073] The tibias were subjected to breaking strength test using an Instron instrument (Model 1011 Instron Universal Testing Machine, Instron Corp., Canton, USA, MA) with Automated Materials Test System software version 4.2. The samples were placed on vertical brackets set 40 mm apart and a 10 mm compression rob was positioned near the center of the bone. The instrument was equipped with a 50 kg load cell and a crosshead speed of 50 mm/min was used during the breaking strength determination. Following the breaking strength test, the broken tibia samples were collected and dried for 24 h at 105° C. in a drying oven (Qualtex Universal Series 2000, Watson Victor Ltd., Perth, Australia) and reweighed after cooling in a desiccator. The dried tibias were then ashed in a Carbolite CWF 1200 chamber furnace (Carbolite, Sheffield, UK) at 600° C. for 6 hours after starting at 300° C. with a 1 h ramp up time. Moisture-free tibia ash was expressed as the percentage of tibia ash relative to dry tibia weight. The ash samples were further ground. The mineral content of the tibia ash and diets samples were determined using inductively coupled plasma-optical emission spectrometer (ICP-OES) (Agilent, Mulgrave, Victoria, Australia).

[0074] Blood samples were allowed to clot for 30 mins at room temperature and then centrifuged at 3,000×g for 10 min at 4° C. (SIGMA 4-15 Lab Centrifuge, Germany) to separate the serum. Individual serum samples were analyzed for ammonia, uric acid, total protein, high density lipoprotein (HDL), low-density lipoprotein (LDL) cholesterol and triglyceride, calcium, phosphorous, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) on Thermo Scientific™ Indiko™ and Konelab™ auto-analyzer, using a kit package specific to each test.

[0075] Ileal digesta samples were weighed and then oven dried at 95° C. for 24 hours to a constant weight. The dried samples were reweighed, and the weight difference was used to calculate digesta water content.

[0076] Statistical Analysis

[0077] Data were checked for normality and then subjected to statistical analysis using 2-way ANOVA of GLM procedure of SAS to assess the main effects of crude protein levels, AvP, and their interaction. Each pen was considered an experimental unit and the values presented in the tables are means with pooled standard error of mean (SEM). If a significant effect was detected, differences between treatments or main effects were separated by least square differences test. Significance was considered at P<0.001, P<0.01, P<0.05 and P<0.1 was indicated as a trend.

[0078] Results

[0079] Analyzed nutrient concentrations in the experimental diets are expressed in Table 5 and confirmed that diets had been correctly formulated and mixed. The desired crude protein, total phosphorus and electrolyte levels were achieved and within acceptable ranges for sampling and analytical error.

[0080] The interactive effects of crude protein and available P on the performance of broiler chickens is presented in Table 6. Increasing crude protein and available P concentration resulted in an increase (P<0.01) in bodyweight on d24 and d35 and for feed intake in both grower and finisher phases. There was no interaction (P>0.05) between dietary crude protein and available P for bodyweight or feed intake. Increasing available P generated a reduction in FCRc that was dependent on dietary crude protein concentration resulting in a significant protein*P interaction. Indeed, increasing available P in the diet with standard protein concentration had no effect on FCRc whereas in the moderate and low protein diets a reduction in FCRc of approximately 3.5 and 7 points respectively was achieved.

[0081] The effect of dietary protein and available P concentration on carcass composition and water content of the ileal digesta is presented in Table 7. There were no effects (P>0.05) of available P concentration on any of the carcass parameters measured or on ileal digesta water content and no interaction (P>0.05) between protein and P on these parameters. However, there was a tendency (P=0.09) for breast yield to increase with increasing available P concentration. Increasing dietary crude protein concentration resulted in a significant increase in the water content of ileal digesta and a reduction (P<0.001) in abdominal fat pad concentration.

[0082] The effect of available P and crude protein on tibia breaking strength and mineral content of the bone is presented in Table 8. Increasing dietary crude protein (P<0.001) and available P (P=0.07) independently increased bone breaking strength. Similarly, bone ash concentration was increased (P<0.05) by elevating both available P and crude protein content in the feed. Tbia mineral composition was largely unaffected by diet protein or P concentration although manganese (Mn) and copper (Cu) content were significantly increased with increasing dietary protein content whereas increasing available P generated an increase (P<0.05) in tibia iron (Fe) content.

[0083] The interaction between dietary available P and crude protein concentrations on serum metabolites is presented in Table 9. Increasing dietary protein generated increases in plasma Ca and triglyceride concentration (P<0.01). Increasing dietary available P content resulted in a reduction in plasma uric acid concentration only at moderate crude protein level, resulting in a significant protein*P interaction. Increasing dietary protein content resulted in a reduction (P<0.01) in plasma NH.sub.3. Increasing dietary available P and protein content resulted in an increase (P<0.01) in plasma P concentration. The increase in plasma P associated with increasing dietary available P concentration was more marked in low protein diets resulting in an interaction between available P and crude protein (P=0.05). There was an inconsistent influence of diet available P and protein concentrations on plasma HDL where increases in available P reduced HDL in standard protein diets but the opposite occurred in moderate and low protein diets (P<0.01).

[0084] Plasma AST was independently increased by increases in dietary available P (P<0.05) and protein (P<0.001) although the effect of available P on AST was more apparent in diets with a low protein concentration resulting in a tendency for an interaction between treatments (P=0.06). There was no effect (P>0.05) of dietary treatment on plasma ALT, total protein or LDL.

CONCLUSIONS

[0085] It can be concluded that offering broiler chickens low protein diets supplemented with an array of synthetic amino acids was not fully effective in promoting maximal growth and both bodyweight and FCR were compromised relative to a higher protein diet. However, growth rate and FCR were promoted by addition of available P to the low protein diet and this strategy was effective in restoring performance losses associated with the diet with the lowest protein concentration.