Use of feed additives in low protein diets for poultry

Abstract

The present invention relates to the use of a composition comprising guanidinoacetic acid and glycine in fattening poultry with low protein feed.

Description

[Technical field]

[0001] explanation The present invention relates to the use of a composition comprising guanidinoacetic acid and glycine in fattening poultry with low protein feed. [Background technology]

[0002] Fixation of atmospheric nitrogen can only occur by plants, not by animals. Livestock are kept for meat production, i.e. for the production of animal protein. Livestock can only build their endogenous proteins from the proteins or amino acids they are given. In livestock, these amino acids usually come from plant feed and less from animal feed (e.g. fish meal).

[0003] The aim of meat production is the optimal provision of all necessary nutrients. The optimal composition of the feed can occur under different aspects. These can be the animal's requirements, the animal's welfare, cost considerations or environmental considerations. For example, recommendations of feed composition for different animals are published by the National Research Council (NRC). A review of the historical development of feed composition [Applegate, TJ, Angel, CR (2014) J. Appl. Poult. Res. 23: 567-575] shows the various reasons why the recommendations of the sample have changed over time.

[0004] In addition, new factors are added that were not previously taken into account in the feed composition. For example, feeding high protein feed is harmful from an environmental point of view. Animal waste contains more nitrogen, which is decomposed, for example, into nitrates, which are harmful to water. In addition, more ammonia is released through the air in the barn. In this context, the production of vegetable proteins and additional fertilization with nitrogen fertilizers such as urea must also be mentioned. The benefits of low protein diets for broilers with environmental benefits have been analyzed and described [Aletor VA, Hamid II, Niess E., Pfeffer E. (2000) Journal of Science of Food and Agriculture 80: 547-554].

[0005] Lower cost was listed as another benefit of low protein diets. [Aftab U., Ashraf M., Jiang Z., (2006) World's Poultry Science Journal, 62: 688-701]. Diets high in vegetable protein are generally more expensive than diets low in vegetable protein for the same energy content. Health effects with low protein diets can also be seen. The growth of undesirable or pathogenic bacteria is reduced with low protein diets [Namroud NF, Shivazad M., Zaghari M., (2008) Poultry Science, 87: 2250-2258].

[0006] However, low protein diets can also have disadvantages. Inadequate supply of protein can result in the inability to perform important body functions or insufficient performance of them. Various possible reasons for the adverse effects of low protein diets in broilers and the consequences in the case of a deficiency of selected proteins have been investigated [Khajali F., Widemann RF, (2010) World's Poultry Science, 66: 751-766]. Deeper investigations have shown protein malnutrition, edema formation and reduced growth rate, among other effects in all animals. Clinically-chemically, protein deficiency is accompanied by reduced serum albumin levels, low hemoglobin levels and reduced extracellular potassium. Physical manifestations include frequent infections, diarrhea, hypothermia and cachexia. In broilers, the occurrence of pulmonary hypertension has been described as an effect of protein deficiency nutrition [Behrooj N., Khajali F., Hassanpour H., (2012) British Poultry Science, 53: 658-664].

[0007] In livestock nutrition, it is therefore wise to provide a balanced protein input that is as low in protein as possible to benefit from the advantages of a low-protein diet on the one hand, and rich enough in protein to avoid the symptoms of deficiency on the other hand. In farm operations, due to the natural variations in the feed given and due to the different requirements of each animal, it is difficult or impossible to find the optimal composition precisely, so that the advantages of a low-protein diet only take effect without any disadvantages being observed. In practice, it is observed that on a low-protein diet, the average weight of animals is lower than on a normal diet [Sharifi MR, Khajali F., Jonaghani BA, Pour HH, Safarpour A., ​​(2016) Research on Animal Production, 14: 51].

[0008] Also, deviations in the degree of standard deviation and variance or cannibalism of animals or parts of animals may occur when feeding is changed. The so-called uniformity of livestock depends on many factors. Breeders publish recommendations on this matter [Ross, Broiler Management Handbook 2018, p.109 ff]. Attempts to avoid these disadvantages have been made by adding essential amino acids [Jiang Q., Waldroup P., Fritts C., (2005), Int. J. Poult. Sci. 4:115-122]. However, the addition of one essential amino acid did not offset the disadvantages of a low protein diet versus a standard diet, nor did supplementation with a combination of essential amino acids [Si J., Fritts C., Burnham D. (2004) Int. J. Poult. Sci. 94:1157-1568].

[0009] Further attempts to avoid these disadvantages were made by adding non-essential amino acids. Supplementation with proline, glutamic acid and aspartic acid did not show the desired effect [Corzo A., Fritts C, Kidd M., (2005) Anim. Feed Sci. Tech. 118:319-327]. When glycine was added to a low-protein diet containing 16% crude protein, a positive effect occurred [Dean D, Bidner T., Southern L. (2006) Poult. Sci. 85:288-296; Awad E., Zulkifli I., (2015) Poult. Sci. 94:2772-2777]. These effects can be explained by the fact that glycine is essentially found in feather keratin and that glycine supplementation largely prevents feather loss.

[0010] In summary, there is still no economical way to completely offset the disadvantages of low protein diets for poultry. Summary of the Invention [Means for solving the problem]

[0011] The object of the present invention is therefore to provide a feed additive for fattening poultry, which when fed with a low protein feed, significantly increases the weight of the birds at the end of fattening compared to feeding a low protein feed alone, and preferably achieves the weight obtained when fed with a balanced high protein feed. The present invention further relates to providing a feed additive for fattening poultry, which when fed with a low protein feed, significantly improves the uniformity of the weight of the birds at the end of fattening compared to feeding a low protein feed alone, and preferably achieves the uniformity obtained when fed with a balanced high protein feed. The object of the feed additive is therefore to reduce the standard deviation from the median slaughter weight at the end of fattening. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] This object is solved by the use according to claim 1. Preferred embodiments of the invention are given in the dependent claims, which can be combined with one another as appropriate.

[0013] Thus, according to a first embodiment, the use of i) a composition containing guanidinoacetic acid and glycine and ii) a low-protein poultry feed having a crude protein content in the range of 14.0 to 18.5 wt. % (based on the total weight of the feed) during fattening from the 11th to 39th day of the poultry's life for improving the fattening performance of poultry and / or for increasing the slaughter weight of poultry and / or for improving the uniformity of the slaughter weight of poultry is the subject of the present invention.

[0014] Essential to the invention is the use of a composition comprising guanidinoacetic acid and glycine and a low protein feed in poultry fattening. In this respect, according to the invention, a low protein feed means a feed having a crude protein content in the range of 14.0-18.5 wt. % (based on the feed). The crude protein content according to the invention was determined by Kjeldahl nitrogen content using a Buchi, AutoKjeldahl Unit K-370 instrument. Multiplying the N content by 6.25 gives the crude protein content. This is based on the assumption that an average protein contains 16 wt. % nitrogen.

[0015] According to a preferred use, it is thereby provided that the low protein feed for poultry has a crude protein content in the range of 14.0 to 18.0 wt. %, more preferably in the range of 15.0 to 18.0 wt. %, even more preferably in the range of 16.0 to 18.0 wt. %, and particularly preferably in the range of 16.5 to 18.0 wt. %, and most preferably of 17.5 wt. % (based on the total weight of the feed).

[0016] It is further essential for the present invention that the composition and the low protein feed are used during fattening from day 11 to day 39 of the poultry's life (hereinafter also called fattening phase), and therefore outside the first growth phase of the animals, including days 1 to 10 of the poultry's life (hereinafter also called starter phase). In the fattening phase, a significantly higher amount of feed is consumed in absolute terms and per day compared to the starter phase, and a higher weight gain per day is achieved. It is therefore particularly economically interesting to use low protein feed in this fattening phase and not to intervene in the diet recommended in the delicate starter phase from days 1 to 10. The phase starting from day 40 is also not covered by the present invention, since the protein requirement in the diet decreases with increasing age and weight, and, moreover, in modern animal fattening, interest in heavier and therefore older animals is only in very limited cases.

[0017] In this regard, according to the present invention, the composition comprising guanidinoacetic acid and glycine and a low protein feed for poultry is used on at least the first day of the poultry's life, more preferably at least the fifth day, even more preferably at least the tenth day, particularly at least the twentieth day and most preferably every day from the eleventh day to the thirty-ninth day.

[0018] A particularly preferred embodiment provides that the composition consists of guanidinoacetic acid and glycine.

[0019] Guanidinoacetic acid (syn. glycocyamine, N-guanylglycine, N-amidinoglycine; C 3 H 7 N 3 O 2 Guanidinoacetic acid (CAS No. 352-97-6) has been commercially available as a feed additive for some time and is approved for use in poultry fattening. Among other things, several studies have shown that guanidinoacetic acid improves feed intake and enhances fattening performance.

[0020] Glycine (syn. glycolic acid, aminoacetic acid, aminoethanoic acid; C 2 H 5 NO 2 ;CAS No. 56-40-6) is approved in the EU as food additive E640 without quantity restrictions and has also been commercially available as a feed additive for some time. Studies on chickens [Corzo A., Kidd, MT (2004) Poult. Sci. 83(8), 1382-4)] have shown that glycine is a limiting nutrient, but is also produced by the animal itself.

[0021] In contrast to creatine, guanidinoacetic acid and its salts show significantly higher stability in acidic aqueous solution and are only converted to creatine under physiological conditions. Guanidinoacetic acid is only converted to creatine after absorption, especially in the liver. Thus, in contrast to creatine, the majority of administrated or fed guanidinoacetic acid is not degraded by unstable reactions, for example, in the stomach, and is not excreted before absorption, but is actually available for the corresponding metabolic reactions.

[0022] Surprisingly, feeding experiments have now shown that administration of a composition comprising guanidinoacetic acid and glycine provides the desired benefits, i.e. improving the fattening performance and fattening weight of animals at the end of fattening, and when fed a low protein diet to improve the weight uniformity of animals.

[0023] These chickens receiving a low-protein diet enriched with guanidinoacetic acid and glycine achieved better growth and higher slaughter weights than a control group receiving the same low-protein diet but without the addition of guanidinoacetic acid and glycine. This effect was observed in comparison with a diet enriched with glycine alone, as well as in comparison with a diet enriched with guanidinoacetic acid alone, where, quite surprisingly, a synergistic effect of the two individual substances is observed.

[0024] In the animal body, the non-essential amino acid glycine can be formed from 3-phosphoglycerate, an intermediate of glycolysis, via serine as an intermediate step. In a further step, guanidinoacetic acid is formed from glycine and L-arginine. Guanidinoacetic acid is further methylated to creatine. Creatine plays an important role in providing energy to cells. Since guanidinoacetic acid is formed from glycine, it was not expected that a positive synergistic effect would occur when both components were administered. Therefore, without being bound by theory, it is speculated that the simultaneous administration of guanidinoacetic acid and glycine shows a positive effect that is not related to energy metabolism.

[0025] The administration of the composition according to the invention comprising guanidinoacetic acid and glycine can be realized in different ways. Thus, the composition can be used as a solid formulation mixed with low-protein feed or dissolved in water as a drinking solution. Thus, the subject of the present invention is also a preferred use in which the composition is provided to poultry a) as a solid formulation mixed with low-protein feed or b) as a drinking solution separately from low-protein feed. In either case, the drinking solution, the low-protein feed or the low-protein feed as a solid formulation with which the composition is mixed should be provided ad libitum. Thus, the subject of the present invention is also a preferred use in which the composition is provided to poultry a) as a solid formulation mixed with low-protein feed or b) as a drinking solution separately from low-protein feed, where the drinking solution and low-protein feed are provided ad libitum.

[0026] In the context of the present invention, the term "ad libitum" is intended to mean an amount of low-protein feed, an amount of drinking solution, or an amount of low-protein feed with which the composition is mixed, that exceeds the daily requirement of the dietary feed and drinking solution, based on the total number of individuals in the fattening. Thus, according to the present invention, the feed or drinking solution should preferably be provided "ad libitum", i.e. in excess, at the free disposal of the poultry.

[0027] Therefore, the suitable free use is clearly different from a specific dosage of active ingredient, for example, administered daily in the form of a fixed amount of 500 mg per day in individual administration and independent of other food or feed.It is even more surprising that the sole provision of a low-protein feed, free, i.e. at the disposal of poultry, and a composition comprising guanidinoacetic acid and glycine, in particular a composition consisting of guanidinoacetic acid and glycine, brings about the desired success, i.e., an improvement in poultry fattening performance and / or an increase in poultry slaughter weight and / or an improvement in the uniformity of poultry slaughter weight.

[0028] It is noted that the use of guanidinoacetic acid in combination with glycine according to the present invention is not limited to the substance itself, but rather that in use both guanidinoacetic acid can be employed as such, i.e. as the free acid or as a salt of guanidinoacetic acid.

[0029] Particularly preferably, a salt selected from the group of alkali metal or alkaline earth metal salts of guanidinoacetic acid can be used as the salt, with sodium guanidinoacetate, potassium guanidinoacetate, magnesium guanidinoacetate or calcium guanidinoacetate being particularly preferred.

[0030] It is further indicated that glycine can be used as such, i.e. as the free acid, or in the form of a salt of glycine. Particularly preferably, a salt selected from the group of the alkali metal or alkaline earth metal salts of glycine can be used, in particular sodium glycinate, potassium glycinate, magnesium glycinate or calcium glycinate.

[0031] Thus, the composition i) guanidinoacetic acid, either as the free acid or in the form of a salt of this acid, and / or ii) glycine as the free acid or in the form of a salt of this acid Preferred uses of the present invention which comprise and in particular consist of these are also encompassed.

[0032] However, the use of a composition which contains guanidinoacetic acid as the free acid and glycine as the free acid is particularly preferred. The use of a composition which consists of guanidinoacetic acid as the free acid and glycine as the free acid is quite particularly preferred.

[0033] In connection with the underlying research, it is shown that the amount of guanidinoacetic acid and glycine used is limited to a certain level and ratio.Particularly good results can be obtained when guanidinoacetic acid is used in an amount of at least 0.01 wt.%, preferably at least 0.02 wt.%, more preferably at least 0.03 wt.%, more preferably at least 0.04 wt.% and more preferably at most 0.20 wt.%, more preferably at most 0.15 wt.%, more preferably at most 0.12 wt.%, particularly preferably at most 0.10 wt.% and very particularly preferably at most 0.08 wt.% (in each case based on low protein feed).

[0034] Insofar as guanidinoacetic acid and / or glycine are not used as free acids but in the form of salts, the weight data herein always refer to the proportion of guanidinoacetic acid in the guanidinoacetic acid salts or the proportion of glycine in the glycine salts.

[0035] Further good results can be obtained when glycine is present in an amount of at least 0.01 wt.%, preferably at least 0.02 wt.%, more preferably at least 0.03 wt.%, more preferably at least 0.04 wt.% and more preferably at the same time at most 0.20 wt.%, more preferably at most 0.15 wt.%, more preferably at most 0.12 wt.%, particularly preferably at most 0.10 wt.% and very particularly preferably at most 0.08 wt.% (in each case based on the low protein feed).

[0036] According to a preferred embodiment of the use according to the invention, it is therefore provided that guanidinoacetic acid is used in an amount of 0.01 to 0.20 wt. %, preferably 0.02 to 0.15 wt. % and particularly preferably 0.04 to 0.10 wt. % (in each case based on the low-protein feed) and / or glycine is used in an amount of 0.01 to 0.20 wt. %, preferably 0.02 to 0.15 wt. % and particularly preferably 0.04 to 0.10 wt. % (in each case based on the low-protein feed).

[0037] According to a preferred embodiment of the present invention, the use may be such that the composition is provided as a solid formulation mixed with a low-protein feed for poultry.More preferably, the composition is provided as a solid formulation mixed with a low-protein feed for poultry, wherein the composition contains guanidinoacetic acid in an amount of 0.01 to 0.20 wt.%, preferably 0.02 to 0.15 wt.%, and particularly preferably 0.04 to 0.10 wt.% (in each case based on the low-protein feed) and / or the composition contains glycine in an amount of 0.01 to 0.20 wt.%, preferably 0.02 to 0.15 wt.%, and particularly preferably 0.04 to 0.10 wt.% (in each case based on the low-protein feed), and in the amounts specifically mentioned.

[0038] According to a further preferred embodiment of the invention, the use is such that the composition is provided as a solid formulation mixed with a low protein feed for poultry, the composition consisting of guanidinoacetic acid in an amount of 0.03-0.08 wt. % and glycine in an amount of 0.03-0.08 wt. % (both based on the low protein feed).

[0039] More preferably, a composition comprising guanidinoacetic acid and glycine, in particular consisting of guanidinoacetic acid and glycine, may be used, in which the weight ratio of guanidinoacetic acid to glycine is in the range of 2:1 to 1:2, preferably 1.8:1 to 1:1.8, more preferably 1.5:1 to 1:1.5, particularly preferably 1.3:1 to 1:1.3, and most preferably 1:1.

[0040] It is particularly preferred to use a composition consisting of equal parts guanidinoacetic acid and glycine.

[0041] According to a very particularly preferred embodiment of the invention, the use is such that the composition is provided as a solid formulation mixed with low-protein feed for poultry, the composition consisting of guanidinoacetic acid in an amount of 0.03 to 0.08 wt. % and glycine in an amount of 0.03 to 0.08 wt. % (in each case based on the low-protein feed), and the weight ratio of guanidinoacetic acid to glycine is in the range of 1.5:1 to 1:1.5, in particular 1:1.

[0042] According to a preferred embodiment of the present invention, the use may be such that the composition is provided to poultry as a drinking solution separately from the feed. Such a drinking solution contains water and the composition. Furthermore, the use may be particularly preferably carried out when drinking water, spring water, well water or tap water is used as water.

[0043] Particularly preferably, such a drinking solution comprises water, guanidinoacetic acid in an amount of 0.05 to 1.2 g per liter of water and glycine in an amount of 0.05 to 1.2 g per liter of water.

[0044] Thus, according to a further idea, the use can also be such that the composition is provided to the poultry as a drinking solution and the drinking solution contains water, guanidinoacetic acid in an amount of 0.05 to 1.2 g per liter of water, in particular 0.1 to 0.9 g per liter of water, in particular 0.15 to 0.6 g per liter of water and particularly preferably 0.2 to 0.5 g per liter of water, and glycine in an amount of 0.05 g to 1.2 g per liter of water, in particular 0.1 to 0.9 g per liter of water, in particular 0.15 to 0.6 g per liter of water and particularly preferably 0.2 to 0.5 g per liter of water.

[0045] More preferably, the use may also be such that the composition is provided to the poultry as a drinking solution, and the drinking solution contains water, guanidinoacetic acid in an amount of 0.05 to 1.2 g per litre of water and glycine in an amount of 0.05 g to 1.2 g per litre of water, wherein the weight ratio of guanidinoacetic acid to glycine is in the range of 1.5:1 to 1:1.5, in particular 1:1.

[0046] The invention described herein can be applied to a variety of different poultry. Particularly preferably, the composition containing guanidinoacetic acid and glycine, in particular consisting of guanidinoacetic acid and glycine, and the low protein feed can be used in poultry selected from the group consisting of chickens, broilers, pullets, and pullets.

[0047] Furthermore, the studies on which the present invention is based show that the low-protein feed used should have a defined calorific value. On the one hand, the low-protein feed should not fall below the calorific value defined for normal nutrition and healthy growth, and on the other hand, should not exceed said calorific value in order to avoid obesity. Thus, good results are obtained when the poultry feed has a calorific value of 8 MJ to 20 MJ per kg feed, in particular 10 MJ to 15 MJ per kg feed, and / or when the feed is 20 MJ per kg, in particular 20 MJ per kg, in accordance with the Animal Nutrition Handbook, 3 rd This is indicated when the diet is balanced according to the Poultry Nutrition and Feeding Standards, 2014 Section 12.

[0048] In this context, both the process and the use are carried out in a particularly preferred manner when the low-protein feed contains at least one cereal, flour, meal or extract thereof. Further preferred is the use in which the at least one cereal, flour, meal or extract thereof is selected from the following group: a. corn, corn flour, corn meal or extracts thereof; b. Millet, millet flour, millet meal or extracts thereof; c. Soybeans, soybean flour, soybean meal or extracts thereof; d. Wheat, flour, wheat meal or extracts thereof; e. Barley, barley flour, barley meal or extracts thereof; f. Sunflowers, sunflower flour, sunflower meal or extracts thereof; and / or g. Rapeseed, rapeseed meal or rapeseed pomace.

[0049] Furthermore, the use can be particularly preferably carried out if the low-protein feed contains at least one further feed additive, in particular a further feed additive from the group of minerals, amino acids and vitamins. Very particularly preferably, this feed additive can be selected from the group consisting of calcium carbonate, mono- or di-calcium phosphate, lysine, methionine, threonine, tryptophan, valine, arginine and vitamins, and mixtures thereof.

[0050] Thus, a preferred basal feed contains essentially corn or corn components, millet or millet components, wheat or wheat components, barley or barley components, sunflower or sunflower components.

[0051] In particular, the preferred feed contains limited amounts of protein-rich feed from rapeseed and soybean plants.

[0052] In particular, the present invention relates to a composition containing guanidinoacetic acid and glycine for use as a feed additive for poultry, especially for fattening poultry, in feeding low protein diets to improve the performance and weight of the animals at the end of fattening and to improve the weight uniformity of the animals.

[0053] Preferred embodiments for the compositions according to the invention are described in the uses according to the invention.

[0054] The following examples are provided to illustrate the present invention.

[0055] Working Example 66,000 Ross 308 broiler chickens, aged 11 days, i.e. at the beginning of the growing phase (rearing), were distributed equally in 6 identical barns at the beginning of fattening. They were fed pellets (diameter < 3 mm, length < 7 mm) until the end of the experiment. The composition of the diet was constant within the groups and was not adjusted until the end of the experiment.

[0056] The temperature was between 20°C and 23°C, and the humidity was between 60% and 75%. Water was provided via nipple drinkers, 12 animals per nipple, and the height of the nipple drinkers was adjusted to the age of the animals. In the feeding dish system, 45 animals shared one feeding dish. The litter depth was 5 cm, and the litter was evenly distributed.

[0057] For example, a crude protein content of 21.5 wt. % between days 11 and 24 and 19.5 wt. % from day 25 to sale is given as recommendation for Ross broilers. For low protein diets, a crude protein content at least 10% lower than the recommendation was set, thus a crude protein content of 17.5 wt. %. The crude protein content was identified by determining the N content of the finished feed mixture using the Kjeldahl method, assuming that the protein has a nitrogen content of 16 wt. %.

[0058] The feed mixture was made with corn, soybean flour, soybean oil, calcium phosphate, cereal grits, salt, sodium bicarbonate, vitamin supplement: per kg additive, vitamin A 13,000 lE, vitamin D3 5,000 IE, vitamin E 100 mg, copper 10 mg, selenium 0.42 mg. To produce the low protein diet, the amount of corn was increased and the amount of soybean flour was decreased. A constant concentration of methionine was maintained by further addition to the low protein diet, resulting in 0.57% methionine in the diet for both alternatives. Metabolizable energy was adjusted to 3200 kcal / kg.

[0059] Otherwise, mixtures were prepared according to the recommendations in the Nutrition Specification for Ross Broiler, Table 2 [http: / / tmea.aviagen.com / assets / Tech_Center / Ross_Broiler / RossBroilerNutritionSpecs2019-EN.pdf].

[0060] Thus, the difference between the two feed mixtures was the crude protein content: the standard diet had a crude protein content of 19.8 wt. %, while the low protein diet had a crude protein content of 17.5 wt. %. From the low protein diet, four other alternatives to the low protein diet were prepared by adding guanidinoacetic acid (GAA) or glycine (Gly) or guanidinoacetic acid and glycine. Pellets of the above sizes were extruded with all feed mixtures.

[0061] Thus, the following diets were available: Experiment 1 (V-1): Standard diet with 19.8 wt.% crude protein Experiment 2 (V-2): Low protein diet with 17.5 wt% crude protein Experiment 3 (V-3): Low protein diet with 17.5 wt% crude protein and 0.05 wt% GAA Experiment 4 (V-4): Low protein diet with 17.5 wt% crude protein and 0.1 wt% GAA Experiment 5 (V-5): Low protein diet with 17.5 wt% crude protein and 0.05 wt% Gly Experiment 6 (V-6): Low protein diet with 17.5 wt% crude protein and 0.05 wt% GAA and Gly, respectively.

[0062] In the 6 groups, the animals were provided with the above diet ad libitum and with water ad libitum as well. At the end of the experiment after 38 days, the animals were removed and the average live weight was determined. Stall losses were comparable for all experimental groups, ranging from 2.18% to 2.30%.

[0063] For the collection of standard deviations (SD), 100 individual animals from each experimental group were weighed individually during the collection process, and from this the standard deviation was determined. To make the standard deviations of different experiments comparable, the standard deviation of experiment 1 was normalized to a value of 1 and was called the "normalized standard deviation" (SDnorm). The SDnorm of experiments 2-6 was determined by dividing their respective standard deviations by the standard deviation of experiment 1. The results are shown in Table 1 below.

[0064] [Table 1]

[0065] As expected, the highest final weight of 2120 g and the lowest standard deviation from the mean final live weight were obtained in experiment 1, where the feed composition followed the recommendations. A significantly reduced final live weight of 2005 g was found in the low protein diet without further addition, i.e. where the amount of protein in the diet was reduced by 10% with respect to the official recommendations (experiment 2). The SDnorm of 1.31 is significantly higher than the standard value of 1, proving the large heterogeneity of the livestock.

[0066] Both the addition of GAA at various concentrations in experiments 3 and 4 and the addition of Glyci in experiment 5 resulted in only a slight improvement in final body weight from 2005 g to 2034 g, 2027 g, and 2016 g, respectively, for the low protein diet in experiment 2. However, improved uniformity of the animals was achieved, especially when feeding GAA in experiments 3 and 4, and the SDnorm was 1.17 and 1.14. This represents a significant improvement over 1.31 for the low protein diet in experiment 2, but still significantly different from the uniformity for the standard diet in experiment 1.

[0067] In experiment 6, where the diet was supplemented with GAA and glycine, the final body weight of 2115 g was close to that of comparison group 1. The SDnorm of 1.07 was only slightly above the comparison value of experiment 1.

[0068] Thus, quite surprisingly, supplementation of a low protein basal diet with glycine and guanidinoacetic acid was shown to almost completely offset the disadvantages of the low protein diet on growth and uniformity.

Claims

1. Use of i) a composition containing guanidinoacetic acid and glycine and ii) a low protein poultry feed having a crude protein content in the range of 14.0 to 18.5 wt. % (based on the total weight of the feed) during fattening from day 11 to day 39 of the poultry's life for improving the fattening performance of poultry and / or for increasing the slaughter weight of poultry and / or for improving the uniformity of the slaughter weight of poultry.

2. 2. The use according to claim 1, characterized in that the composition is provided as a solid formulation mixed with a low-protein feed for poultry or that the composition is provided as a drinking solution for poultry separately from the low-protein feed.

3. 3. Use according to any one of claims 1 to 2, characterized in that the composition contains guanidinoacetic acid as a free acid or in the form of a salt of this acid and / or that the composition contains glycine as a free acid or in the form of a salt of this acid.

4. 4. Use according to any one of claims 1 to 3, characterized in that guanidinoacetic acid is used in the form of a salt of guanidinoacetic acid, which is selected from the group of the alkali metal or alkaline earth metal salts of guanidinoacetic acid, in particular sodium guanidinoacetate, potassium guanidinoacetate, magnesium guanidinoacetate or calcium guanidinoacetate.

5. 5. Use according to at least one of claims 1 to 4, characterized in that glycine is used in the form of a salt of glycine, which is selected from the group of the alkali metal or alkaline earth metal salts of glycine, in particular sodium glycinate, potassium glycinate, magnesium glycinate or calcium glycinate.

6. Use according to any one of claims 1 to 5, characterized in that guanidinoacetic acid is used in an amount of from 0.01 to 0.20 wt. %, preferably in an amount of from 0.02 to 0.15 wt. % and particularly preferably in an amount of from 0.04 to 0.10 wt. % (in each case based on the low-protein feed).

7. Use according to any one of claims 1 to 6, characterized in that glycine is used in an amount of from 0.01 to 0.20 wt. %, preferably in an amount of from 0.02 to 0.15 wt. % and particularly preferably in an amount of from 0.04 to 0.10 wt. % (in each case based on the low-protein feed).

8. 8. Use according to any one of claims 1 to 7, characterized in that the composition is provided as a drinking solution for poultry and that the drinking solution contains water, guanidinoacetic acid in an amount of 0.05 to 1.2 g per liter of water and glycine in an amount of 0.05 to 1.2 g per liter of water.

9. Use according to any one of claims 1 to 8, characterised in that guanidinoacetic acid and glycine are used in a weight ratio of guanidinoacetic acid to glycine ranging from 2:1 to 1:

2.

10. Use according to any one of claims 1 to 9, characterized in that the poultry are selected from the group consisting of chickens, broilers, pullets and hens.