Use of an animal feed additive for feeding pregnant sows

Abstract

The invention relates to the use of guanidinoacetic acid (GAA) or an animal feed additive comprising guanidinoacetic acid for feeding pregnant sows in order to improve weight gain in piglets during the rearing phase, and no GAA has to be fed to the piglets themselves.

Description

[0001] Use of a feed additive for feeding pregnant sows

[0002] Description:

[0003] The present invention relates to the use of a feed additive comprising guanidinoacetic acid for feeding pregnant breeding sows to improve the growth of the piglets after weaning.

[0004] The optimization of feed is an ongoing process that must be taken into account with many different aspects. Firstly, all of the nutrients that an animal needs must be available in sufficient quantities in the feed. In addition to nutrient requirements, animal health is another factor that determines the optimal feed composition. Furthermore, the requirements of the feed also differ according to the different development phases of the animals. For example, an increased protein requirement is usually when rearing young animals. In addition, numerous other factors must be taken into account, such as environmental aspects, regulations on fertilization and emissions during feed production. In order to meet these requirements, the protein content of the feed is usually reduced in order to lower the nitrogen and phosphorus content in the animals' excrement, e.g. in liquid manure.Even when taking all these requirements for modern feed into account, the performance of the animals during rearing and fattening must of course not suffer.

[0005] To meet the requirements of modern feed, various feed additives are now used. The primary goal is to compensate for deficiencies in the feed mix through the targeted addition of essential and growth-limiting nutrients. Examples include essential amino acids, calcium and magnesium, as well as trace elements and vitamins. The use of creatine or guanidinoacetic acid in pig farming, in contrast, has been little studied to date.

[0006] In various studies by Panisson JC et al. (EAAP Scientific Series, Vol. 138, 2019, p.

[0007] 183) and Schneider L. et al. (Animal - Science Proceedings 13, 2022, p. 165), only the effect of guanidinoacetic acid on productive sows and on fetal and postnatal piglet development has been investigated to date. Improvements in piglet rearing, particularly after weaning, have not been the subject of corresponding studies to date. WO 2005 / 120246 A1 describes the use of guanidinoacetic acid in the rearing and fattening of farm animals to support animal growth, improve meat quality, and improve animal health. WO 2021 / 175677 A1 describes a reduction in the aggressiveness of pigs, which is a particular problem in animal fattening. The use of guanidinoacetic acid in the feeding of pregnant sows is not described.

[0008] In Mendonca, IB et al., Livestock Science, Vol. 227, 2019, pp. 105-110, the effect of guanidinoacetic acid on pregnant sows and their piglets during lactation was investigated. No effect of guanidinoacetic acid on piglet performance or blood parameters was found. The authors conclude that administering guanidinoacetic acid to pregnant sows and their piglets is not economically viable.

[0009] The present invention is therefore based on the object of providing a feed additive which improves the performance of piglets during rearing and in particular their weight gain after lactation or after weaning.

[0010] This problem is solved by administering guanidinoacetic acid (GAA) or a feed additive containing guanidinoacetic acid to sows. It is sufficient to administer the feed additive to the sows during pregnancy. Although the piglets themselves do not receive the feed additive containing guanidinoacetic acid, piglets whose sows received guanidinoacetic acid gain more weight. Surprisingly, the weight differences are particularly evident in the later rearing phase, after weaning.

[0011] Thus, a first aspect of the present invention is the use of guanidinoacetic acid (GAA) or a feed additive comprising guanidinoacetic acid for feeding sows during pregnancy and optionally during lactation to improve the weight gain of piglets during their rearing phase. Surprisingly, it was discovered according to the invention that the performance of piglets, and in particular an improvement in weight gain, i.e., an increase in the weight gain of piglets during their rearing phase, can be achieved by administering guanidinoacetic acid to the sows of the piglets during pregnancy, without the piglets themselves having to be administered guanidinoacetic acid.

[0012] According to the invention, an improvement in piglet performance is understood in particular to mean an improvement in piglet weight gain. An improvement in weight gain is in particular an increase in weight gain, preferably more than 2% higher, preferably more than 4% higher, even more preferably more than 6% higher, and most preferably more than 8% higher than the weight gain of piglets reared under the same conditions, but whose sows were not administered guanidinoacetic acid during pregnancy. The weight gain of the piglets is preferably determined on day 40 and / or on day 50 and / or on day 67 and / or on day 77 after the piglets' birth. The starting point for determining weight gain is preferably the day of birth of the piglets, day 14 after birth, and more preferably the day of weaning or day 24 after birth.

[0013] In particular, the invention relates to the use of the feed additive comprising GAA in pregnant sows to improve the weight gain of their piglets in a period beginning from day 14 to 42 after the birth of the piglets, and / or in particular beginning with weaning of the piglets, up to day 40 to 120 after the birth of the piglets, wherein the piglets show improved weight gain, especially in a period after weaning up to day 90 after birth, compared to piglets whose sows are kept without the addition of guanidinoacetic acid but otherwise under the same conditions and piglet rearing after weaning also takes place under the same conditions. For the purposes of the present invention, the term "piglet rearing" also includes the rearing phase of piglets (fattening and breeding piglets).

[0014] Feeding trials have surprisingly shown that the improved weight gain of piglets whose sows received guanidinoacetic acid during pregnancy is 4% or more, based on birth weight or alternatively based on weaning weight. Depending on the feeding trial, the weight gain was determined on day 67 (feeding trial 1) or day 77 (feeding trial 2) after the birth of the piglets.

[0015] The rearing phase begins with the birth of the piglets and preferably lasts until day 120 after the birth of the piglets, more preferably until day 90, in particular until day 77, even more preferably until day 67 after the birth of the piglets. Preferably, the period of the rearing phase in which an improvement in the weight gain of piglets is observed according to the invention is from weaning of the piglets until day 90, in particular until day 40, after the birth of the piglets.

[0016] Surprisingly, it was found that a particularly pronounced effect on improving piglet weight gain was observed in piglets of gilts, i.e., sows that were pregnant for the first time. Therefore, the use of a feed additive containing guanidinoacetic acid or guanidinoacetic acid in the feeding of pregnant gilts is particularly preferred for improving piglet weight gain during the rearing period.

[0017] The mechanism by which the improved rearing performance is achieved is not entirely clear. However, it is likely that the improved piglet weight gain is related to an improved creatine supply to the fetuses by the pregnant sows. In contrast, the creatine content in the milk of lactating sows administered guanidinoacetic acid differs little from the creatine content in the milk of untreated sows.

[0018] According to the invention, guanidinoacetic acid or a feed additive comprising guanidinoacetic acid is administered to pregnant sows. Administration can take place over the entire period from insemination of the sows until farrowing or in partial periods thereof, preferably for at least 10 days from insemination of the sows until farrowing, more preferably for at least 20 days from insemination of the sows until farrowing.

[0019] Based on the total weight of the feed, a quantity of guanidinoacetic acid of 0.02 wt.% to 1 wt.%, preferably 0.05 wt.% to 0.5 wt.%, can be added to the feed to achieve improved weight gain in the piglets. With long-term administration of guanidinoacetic acid to the sows, relatively low amounts, preferably in the range of 0.05 wt.% to 0.25 wt.% based on the total weight of the feed, are sufficient to achieve a significant improvement in the piglets' weight gain. Long-term administration is understood to mean the administration of guanidinoacetic acid for more than 50 days. Guanidinoacetic acid is preferably fed until farrowing, but can also be discontinued earlier.In this case, guanidinoacetic acid is preferably administered at least until day 100 of pregnancy, particularly preferably at least until day 110 of pregnancy, and especially until farrowing, with day 1 of pregnancy being the day of insemination of the sows. Farrowing generally occurs between days 100 and 130 of pregnancy.

[0020] If guanidinoacetic acid is only fed to sows during the last phase of pregnancy and possibly during lactation, it is advantageous to use higher amounts, preferably in the range of 0.15% to 0.4% by weight. In this case, the last phase of pregnancy is understood to be the phase from day 50 of pregnancy, in particular from day 70 of pregnancy until farrowing. Farrowing usually occurs from day 100 to day 130 of pregnancy. Day 1 of pregnancy is understood to be the day on which the sows are inseminated. The administration period of guanidinoacetic acid should preferably not be less than 20 days, but preferably for a period of 30 to 60 days.The administration of guanidinoacetic acid is preferably continued until farrowing, but can alternatively be stopped up to 10 days or, better, only up to 5 days before farrowing, which is usually achieved by administering guanidinoacetic acid until at least day 105 or day 110 of gestation.

[0021] The wording “based on the total weight of the feed” or “based on the feed” refers to a feed with 88% dry matter by weight, unless explicitly stated otherwise.

[0022] In all cases, it can be beneficial to feed the sows an appropriate amount of guanidinoacetic acid during lactation. During lactation, the administration of guanidinoacetic acid in an amount of 0.02% to 1%, preferably 0.05% to 0.5%, based on the total weight of the feed (with 88% dry matter), is also advisable. However, according to the invention, it is also possible not to feed the sows any guanidinoacetic acid during lactation.In a preferred embodiment, the present invention relates to the use of guanidinoacetic acid or a feed additive comprising guanidinoacetic acid in the feeding of pregnant sows to increase the weight gain of piglets after weaning during the rearing phase up to day 90, in particular up to day 77 and preferably up to day 67 after birth, wherein guanidinoacetic acid is administered to the pregnant sows and wherein furthermore the piglets do not receive any GAA during this time, i.e. up to day 90 or up to day 77 or up to day 67 after birth.

[0023] According to the invention, an improvement in weight gain and in particular an increase in the weight gain of the piglets by more than 2% higher, preferably by more than 4% higher, and even more preferably by more than 6% higher than the weight gain of piglets reared under the same conditions, but whose sows were not administered guanidinoacetic acid during pregnancy, is preferably achieved, wherein no guanidinoacetic acid is administered to the piglets themselves. The weight gain of the piglets is preferably determined on day 40 and / or on day 50 and / or on day 67 and / or on day 77 after the birth of the piglets. Although no GAA is administered to the piglets themselves, but only to the pregnant sows, an increase in the live weight of the piglets could be observed according to the invention.

[0024] Guanidinoacetic acid can be used as such or as a component of a feed additive or premix mixed with other additives.

[0025] Guanidinoacetic acid (syn. glycocyamine, N-guanylglycine, N-amidinoglycine; C3H7N3O2; GAA; CAS No. 352-97-6) is commercially available and can be used as the free acid or in the form of a salt of this acid. Preferred salts are selected from the group of alkali or alkaline earth metal salts. Particularly preferred guanidinoacetic acid salts are sodium guanidinoacetate, potassium guanidinoacetate, magnesium guanidinoacetate, or calcium guanidinoacetate.

[0026] Guanidinoacetic acid can be used as a powder or aqueous solution. However, guanidinoacetic acid is preferably used in the form of granules containing a binder. Particularly suitable binders are nutritionally active substances that have a binding effect and enable good granulation of the composition, such as glycine, starch, or sugar. Other suitable binders include methylcellulose, ethylcellulose, carboxymethylcellulose, carboxyethylcellulose, carboxypropylcellulose, hydroxypropylmethylcellulose, hydroxymethylcellulose, microcrystalline cellulose, ethylmethylcellulose and other cellulose derivatives, hydroxypropyl starch, pregelatinized or modified starch, sugar syrup, dextrin, gelatin, propylvinyl alcohol, polyvinylpyrrolidone, xanthan gum, gum arabic, sodium chloride, sodium carbonate, sodium bicarbonate, and glycerin, as well as mixtures thereof.To improve the flowability of the granules, it may be advantageous for them to contain a flow aid, in particular a hydrophilic and / or hydrophobic silica and / or silicate-based additives and / or fatty acids and / or their salts, such as stearic acid or palmitic acid as well as their sodium, potassium and calcium salts.

[0027] The binder is preferably present in the granulated guanidinoacetic acid composition in amounts of 0.05 to 15 wt.%, in particular 0.1 to 1.5 wt.%. The grain size of suitable granules is preferably between 100 and 850 μm, with preferably less than 10 wt.% of the particles being below 100 μm and less than 10 wt.% of the particles being above 850 μm. Accordingly, the moldings preferably have a guanidinoacetic acid or guanidinoacetic acid salt content of 85 to 99.95 wt.%, in particular 95 to 98.5 wt.%. Flow agents and other additives can be present in the granules at up to 5 wt.%.

[0028] Suitable feed additives for pregnant sows may include guanidinoacetic acid as well as other feed additives such as amino acids.

[0029] Amino acids that are suitable as feed supplements are particularly selected from the group consisting of lysine, methionine, threonine, tryptophan, and / or valine. These amino acids are preferably added as free amino acids as feed supplements. Lysine, in particular, is generally not present in sufficient quantities in the crude protein portion of the feed, so additional administration of the amino acid is advisable. The total amount of lysine in the feed for pregnant sows should preferably be in the range of 4g to 8g per 1 kg of feed. The total amount of lysine in the feed refers to the total amount of lysine building blocks in the crude protein present in the feed and the added / contained free amino acid lysine.The content of other amino acids in the feed for pregnant sows in relation to lysine should be in the following ranges: lysine to methionine + cysteine ​​in the range of 0.5 to 0.7, lysine to threonine in the range of 0.55 to 0.75, lysine to tryptophan in the range of 0.15 to 0.25 and lysine to valine in the range of 0.6 to 0.8. The total amount of lysine in the feed should be significantly higher for lactating sows, preferably in the range of 8g to 12g per 1 kg of feed. The content of other amino acids in the feed for lactating sows should be correspondingly higher so that the ratios to lysine are the same as for pregnant sows. The stated contents refer to the total content of the respective amino acid in the feed, i.e. in particular the content of amino acid building blocks in the crude protein and any additional free amino acids present.

[0030] The feed additive containing guanidinoacetic acid can also contain other nutritionally active additives, for example from the group of vitamins, minerals, trace elements, methyl group donors and derivatives of these substances, as well as carbohydrates and fats and mixtures of all these substances. Helpful ingredients are particularly selected from the group of vitamins. Preferred in this context are, for example, vitamin A, vitamin D3, vitamin E, nicotinic acid, nicotinamide and choline. Other preferred ingredients are B vitamins, including thiamine, riboflavin, nicotinic acid, pantothenic acid, biotin, folic acid, cobalamin and vitamin B1. Important minerals and trace elements that can be included as supplements in the feed additive include iron, copper, zinc, manganese, iodine and selenium. L-carnitine is also often given to breeding sows as a additive.

[0031] The optional additives mentioned can be added to the feed additive or directly to the feed.

[0032] Preferably, a feed is used that is adjusted to the crude protein and energy content parameters of pregnant sows. The feed can consist of a base feed and other feed additives. It is further preferred if the feed comprises, as a base feed, at least one plant component, in particular a grain, a grain flour, a grain meal, a grain extraction meal, or a grain semolina, and b) a fat or oil of plant or animal origin.

[0033] Preferred feeds for pregnant and lactating sows are feeds based on wheat, barley, triticale, rye, oats, soybean meal, rapeseed meal, and grain maize. However, other types of feed such as maize grain silage, field beans, peas, dried pulp, rapeseed cake, soybeans, sunflower meal, sugar beet pulp, etc. can also be used. Fiber sources such as fruit pomace, soybean hulls, bran (e.g., wheat bran), and oils or oilseeds from soybeans, rapeseed, and sunflowers can be incorporated into the feed mixture to achieve the desired composition. The feed may also contain other additives such as vitamins, minerals, trace elements, amino acids, methyl donors, etc.

[0034] Feeds based on wheat, barley, triticale, maize, soybean and rapeseed meal are particularly advantageous.

[0035] Feeds for pregnant or lactating sows, which contain a balanced mix of nutrients to meet the sows' specific needs during pregnancy or lactation, generally contain the following components: a) Cereals such as barley, maize, wheat, triticale, rye, millet and / or oats, which serve as a carbohydrate-rich energy source. The grains can also be used in the form of flour, semolina, grits or meal. Preferred are barley flour, maize flour, wheat flour, barley meal, maize meal, wheat meal, wheat meal or mixtures thereof. b) Fats and oils: Fats and oils are a concentrated source of energy and help to improve energy supply. Vegetable oils such as soybean oil, sunflower oil or rapeseed oil are often used, but fats of animal origin are also used.c) Protein sources: Proteins are essential for maintaining body structures and tissues and for fetal development. Typical protein sources in piglet feed are soy, soy meal, soybean meal, soybean extraction meal, rapeseed, rapeseed meal, rapeseed extraction meal, sunflower, sunflower meal, sunflower meal, sunflower extraction meal, or mixtures thereof. d) Crude fiber sources: Fiber- and fiber-rich vegetable ingredients, such as alfalfa, beet pulp, straw, hay, soybean hulls, fruit pomace or bran, especially wheat bran, wheat semolina bran, barley bran and maize bran. e) Fish meal or products of animal origin. f) Vitamins, minerals and trace elements: Pregnant and lactating sows have increased requirements for the provision of vitamins and minerals to ensure a healthy diet. The most important supplements are vitamins from groups A, B, D, E and folic acid and minerals such as calcium, phosphorus, iron and zinc.g) Amino acids: Pregnant and lactating sows have an increased need for certain amino acids such as lysine and, where appropriate, methionine, threonine, tryptophan, and valine. An adequate supply of amino acids, especially essential amino acids, is important not only for the sows themselves, but also for the development of the fetuses and piglets. h) Other additives: Depending on requirements, other additives such as enzymes, creatine, carnitine, or methyl group donors such as betaine and choline, as well as sugars and acids, can be added to the sow feed.

[0036] The energy content of feeds can be selected broadly. The feed should preferably have a metabolizable energy (ME) in the range of 10 MJ / kg to 16 MJ / kg. For feeding pregnant sows, energy concentrations of 11 MJ / kg to 13 MJ / kg and for lactating sows, energy concentrations of 12 MJ / kg to 15 MJ / kg are beneficial for optimal animal nutrition.

[0037] The crude protein content of suitable feeds is typically in the range of 8 to 22 wt.%. For pregnant sows, a crude protein content of 11 to 17 wt.%, especially 12 to 16 wt.%, is preferred. For lactating sows, the crude protein content in the feed is preferably in the range of 14 to 20 wt.%, especially 15.5 to 18.5 wt.%, with the wt.% values ​​based on the total weight of the feed (with 88 wt.% dry matter).

[0038] An adjustment of the crude protein content and the content of metabolisable energy in the feed for pregnant and lactating sows can be achieved simply by weighting the components listed under a) to e).

[0039] The energy content of the feed is adjusted in particular by suitable selection of feed components a) and b). A proportion of 35 to 90 wt.%, preferably between 45 and 80 wt.% of component a) and 0 to 8 wt.%, preferably between 0.5 and 6 wt.% of component b) in the feed is usual. In order to provide sufficient crude protein in the feed, 2 to 40 wt.%, preferably 10 to 35 wt.% of components c) and e) are usually contained in the feed. Component d) is generally contained in the feed in a proportion of up to 35 wt.%, preferably between 3 and 30 wt.%.In accordance with the crude protein and metabolizable energy ranges specified above, it is customary to give higher weighting to the protein- and energy-rich components in feed for lactating sows, and in particular to give lower weighting to the fiber-rich components, than in feed for pregnant sows, in order to achieve the preferred energy and crude protein content in the feed. For pregnant sows, a content of components c) and e) in the feed of 10 to 25 wt.% is preferred, and for lactating sows, 15 to 35 wt.%. The fiber-rich feed components d) are preferably present in the range of 3 to 30 wt.% in the feed for pregnant sows, while in the feed of lactating sows, the content is preferably below 10 wt.% or even below 5 wt. For lactating sows, fiber-rich feed components are often even omitted altogether.

[0040] The effect of guanidinoacetic acid is independent of the energy content of the feed and the amount of energy provided, as long as no deficiency symptoms occur. Therefore, compliance with the respective feed recommendations for pregnant and lactating sows is beneficial. Advantageous results generally arise from regional supply recommendations for pig farming, e.g., by adhering to the recommendations issued by the Bavarian State Office for Agriculture (LfL) in "Feed Calculation for Pigs," 27th edition, August 2022 (especially pages 18-25, 39-43, and 59-68). Among other things, this publication provides supply recommendations and guideline values ​​for gilt rearing, piglet feeding, fattening pig feeding depending on the age of the animals, and for the feeding of pregnant and lactating sows.These recommendations cover a wide range of parameters, such as metabolizable energy (ME), crude protein, lysine and precaecal digestible lysine, methionine and cysteine, tryptophan and threonine, crude fiber content, calcium, digestible phosphorus and sodium.

[0041] Typical analytical values ​​for various types of grain and grain by-products, typical protein feeds, potato and by-products, and beet and beet by-products, as well as green fodder, silage, hay and straw, brewery and dairy products, and other by-products of food processing, oils and oilseeds, as well as additives such as amino acids and minerals, are also listed. It is advantageous to combine the feedstuffs available at each location in such a way that the composition of the final feed corresponds to the previously mentioned recommendations for pregnant and lactating sows. If no analytical values ​​are available, the metabolizable energy (ME) content of the feed can also be calculated using the following formula (Gesellschaft für Ernährungsphysiologie (GfE), 2008: Prediction of metabolizable energy of compound feeds for pigs. Proceedings of the Society of Nutrition Physiology 17, 199-204):

[0042] ME (MJ / kg) = 0.021503 (MJ / g) x XP (g / kg) + 0.032497 (MJ / g) x XL (g / kg) - 0.021071 (MJ / g) x crude fiber (g / kg) + 0.016309 (MJ / g) x starch (g / kg) + 0.014701 (MJ / g) x “digestible residue” (g / kg) (Formula I)

[0043] The formula therefore includes the analyzed contents of crude protein (XP), crude fat (XL), crude fiber, starch and the “digestible residue” (difference between the organic mass and the sum of XP, XL, crude fiber and starch, each in g / kg).

[0044] Commercially available feeds usually list the crude protein, crude fat, crude fiber, and starch content, allowing the metabolizable energy content to be calculated directly. Crude protein, crude fat, crude fiber, and starch content can also be determined using common VDLUFA methods (VDLUFA Methods Book III: 3rd Supplement 1993, Section 4.1.1 (Crude Protein Determination); 2nd Supplement 1988, Section 5.1.1 (Crude Fat Determination); 8th Supplement 2012, Section 7.2.1 (Starch Determination); 3rd Supplement 1993, Section 6.1.1 (Crude Fiber Determination)).

[0045] Guanidinoacetic acid or the feed additive containing guanidinoacetic acid can be administered to the animals depending on the feeding system. Generally, guanidinoacetic acid can be administered with the feed or with water. When administered with the feed, guanidinoacetic acid can be mixed with the finished feed. However, it is advantageous that when preparing the feed mixture, the guanidinoacetic acid is first added to the base feed, i.e., the bulk of the feed, and then the other feed ingredients are added. This has the advantage that no additional mixing time is required. The guanidinoacetic acid can, of course, also be contained in a premix with other additives. When administered with water, it is advantageous to administer it as a salt, for example, as a Na or Ca salt.In general, administration with feed is preferable, as this ensures a more consistent uptake of guanidinoacetic acid in animals. The preferred dosage is based on the feed.

[0046] Dosing into the water is advantageous when a guanidinoacetic acid-free feed mixture is available and the guanidinoacetic acid needs to be dosed easily. However, the water requirements of the animals, depending on their age and temperature, must be taken into account to achieve an appropriate dosage.

[0047] When feeding dry food without water, with water, or with dry food from a dry feeder, the dosage can be added to either the water or the feed. Only if the animal facility also administers other ingredients with the drinking water is it advisable to add guanidinoacetic acid to the water. Otherwise, it has proven easier to administer guanidinoacetic acid in combination with the feed.

[0048] When feeding liquid food, guanidinoacetic acid can be dosed into the liquid feed and is distributed homogeneously by simply stirring.

[0049] Guanidinoacetic acid can be added to feed in a variety of solid preparations or as a solution. It is particularly advantageous to add guanidinoacetic acid to feed in the form of granules, extrudates, or as a solution.

[0050] If the guanidinoacetic acid is used as a solid or solid preparation, the guanidinoacetic acid can also be applied to a carrier material.

[0051] There are a few typical ingredients in the composition of rearing feed for piglets that are intended to meet the animals' nutritional needs and contribute to healthy growth. The exact composition can vary depending on the manufacturer and specific requirements. However, typical piglet feed usually contains the following ingredients: a) Grains, such as barley, corn, wheat, rye, millet and / or oats, which serve as a carbohydrate-rich energy source. The grain can also be used in the form of flour, semolina, grits or meal. Preferred are barley flour, corn flour, wheat flour, barley grits, corn grits, wheat grits, wheat semolina or mixtures thereof. b) Fats and oils: Fats and oils are a concentrated source of energy and help to improve energy supply. Vegetable oils such as soybean oil, sunflower oil or rapeseed oil are often used, but fats of animal origin are also used.c) Protein sources: Proteins are essential for building muscle mass and other tissues. Typical protein sources in piglet feed are soy, soy meal, soybean meal, soybean extraction meal, rapeseed, rapeseed meal, rapeseed extraction meal, sunflower, sunflower meal, sunflower meal, sunflower extraction meal or mixtures thereof. d) Optionally, low-energy ingredients selected from the bran group, in particular wheat bran, wheat semolina bran, barley bran and maize bran. e) Fish meal or products of animal origin such as milk or whey powder with a high protein content, e.g. blood plasma. f) Vitamins, minerals and trace elements: Piglets have specific requirements for vitamins and minerals to ensure healthy development. The most important supplements are vitamins from groups A, B, D and E and minerals such as calcium, phosphorus, iron, copper, zinc, manganese, selenium and iodine.g) Amino acids: Piglets have an increased need for certain amino acids such as lysine, methionine, threonine, tryptophan, and valine for healthy growth. These can be provided in the form of feed additives or special protein sources. h) Other additives: Depending on requirements, other additives such as enzymes, creatine, carnitine, or methyl group donors such as betaine and choline, as well as acids and sugars, can be added to the piglet feed.

[0052] The solubilized feed components a), b) and c) are generally heat- or acid-treated components. The proportion of solubilized components is generally less than 50% by weight, preferably in the range of 0 to 40% by weight, based on the respective feed component a), b), c). The proportion is particularly preferably between 5 and 20% by weight, based on the total weight of the feed. The feed component e) (of animal origin) comprises in particular components with a protein content of more than 15% by weight, e.g. selected from the group consisting of whey protein concentrate, whey fat concentrate, milk powder (including whole and skimmed milk powder), dried blood plasma, PAP (processed animal protein = animal meal (e.g. meat and bone meal, meat meal, blood meal), e.g. based on poultry).

[0053] The feed components a) to e) are selected so that the feed meets the energy and crude protein requirements for piglets. The energy content of the feed is adjusted in particular by appropriate choice of feed components a) and b). A proportion of 45 to 75 wt.%, preferably between 50 and 70 wt.% of component a) and 2 to 10 wt.%, preferably between 3 and 8 wt.% of component b) in the feed is usual. In order to provide sufficient crude protein in the feed, the feed usually contains 15 to 30 wt.% of component c) and 0 to 25 wt.% of component e). Component d) is generally contained in the piglet feed in a proportion of up to 15 wt.%, preferably between 2 and 10 wt.%.

[0054] The feed component e) is generally added in an amount of less than 25 wt.%, in particular between 2 and 15 wt.%, based on the total amount of the feed. In feeds used in the early rearing phase of piglets (10 days to 42 days after birth of the animals), the content of component e) in the feed can be relatively high; component e) is preferably in the range from 3 to 15 wt.%, particularly preferably from 4 to 10 wt.%, based on the total weight of the feed. Feeds used later (from day 31 after birth of the animals or approximately 14 days after weaning, in particular up to day 105 after birth of the animals or approximately 90 after weaning) often contain a smaller amount of component e), preferably up to 5 wt.%, in particular from 0 to 3 wt.%, based on the total weight of the feed.After day 35 after birth of the animals, component e) can be omitted from the feed, preferably from day 42 or later.

[0055] Feeds for piglets have proven advantageous whose components are selected so that they have a) a crude protein content in an amount of 14 to 22 wt.%, in particular 16 to 20 wt.%, and b) a metabolisable energy content ME in the range of 12.5 to 15 MJ ME / kg feed, preferably 13 to 14 MJ ME / kg feed.

[0056] Piglet feed is usually adjusted to the needs of the piglets based on their age and weight. Typically, at least two piglet rearing feeds (FAF) are used, with the first feed (FAF I or Starter I) usually used during the first three weeks after weaning, and the second piglet feed (FAF II or Starter II) used in the following three weeks. After that, a starter feed is preferred. In addition, special prestarter and weaning feeds can be used in the early stages of piglet rearing.

[0057] Suitable piglet feeds are derived from the respective regional supply recommendations for piglet husbandry. These may include, for example, the recommendations issued by the Bavarian State Office for Agriculture (LfL) in "Feed Calculation for Pigs," 27th edition, August 2022 (especially pages 26-28, 39-43, and 59-68). Metabolizable energy can also be determined for piglet feed using Formula I, if necessary.

[0058] Piglet feed used for rearing piglets may also contain guanidinoacetic acid as an additive, but may also be free of it. If guanidinoacetic acid is added to piglet feed, it should preferably be used in an amount ranging from 0.02 to 1% by weight based on the total weight of the piglet feed. As usual, the weight data for piglet feed should also be standardized to a piglet feed containing 88% by weight.

[0059] Preferably, a piglet feed without added guanidinoacetic acid is used for rearing the piglets during the rearing phase. Surprisingly, it has been discovered according to the invention that an improvement, and in particular an increase, in the weight gain of piglets can be achieved by administering guanidinoacetic acid to pregnant sows, without the piglets themselves having to be administered guanidinoacetic acid.

[0060] Further feed additives may be added to the basic feed for piglets or pregnant sows consisting of components a) to e). In particular, in addition to the feed additive used according to the invention, the feed may also contain other feed additives from the group of minerals, amino acids, enzymes, vitamins, trace elements, or mixtures thereof. Furthermore, creatine, carnitine, or methyl group donors, such as betaine and choline, sugars, and acids, such as formic acid and benzoic acid, may also be added to the feed. The proportion of additives in the piglet feed is selected to ensure an adequate supply to the piglets or pregnant sows.

[0061] Particular attention is paid to ensuring that the piglets and pregnant sows are supplied with essential amino acids. To this end, lysine is added to adjust the total lysine content in the piglet feed so that it is preferably in the range of 1.0 to 2.0 wt.%. The lysine content in the feed for pregnant sows is preferably in the range of 0.4 to 1.2 wt.%, and that for lactating sows is preferably in the range of 0.6 to 1.5 wt.%. In both cases, the content of other amino acids is determined in proportion to the lysine content. The lysine : methionine + cysteine ​​ratio in piglet feed is preferably between 1 : 0.45 and 1 : 0.70, the lysine : threonine ratio between 1 : 0.55 and 1 : 0.75, the lysine : tryptophan ratio between 1 : 0.15 and 1 : 0.25 and the lysine : valine ratio between 1 : 0.55 and 1 : 0.80.The stated contents refer to the total content of the respective amino acid in the feed, i.e. in particular the content of amino acid building blocks in the crude protein and any additional free amino acid present.

[0062] Many of these ingredients, especially the additives from groups f), g) and h), are added to the feed in the form of a mixture (premix) to ensure that the animals are adequately supplied with essential nutrients.

[0063] The present invention further relates to a method for improving the weight gain of piglets during the rearing phase, wherein guanidinoacetic acid is administered to the pregnant sows during feeding.

[0064] Examples of implementation:

[0065] In an initial feeding study, a total of 160 gilts were divided into four groups and fed different doses of GAA (guanidinoacetic acid). Gilts are sows that are pregnant for the first time. The doses were 0.00 wt% (control group), 0.12 wt% GAA, 0.24 wt% GAA, and 0.36 wt% GAA based on the total weight of the feed provided. GAA feeding began with the transition to a high-pregnancy feed on gestation day 80, i.e., 35 days before farrowing. GAA was then fed to the sows until weaning. Guanidinoacetic acid was added exclusively to the feed of the pregnant sows, while the piglets were fed a standard feed that did not contain GAA.

[0066] The study parameters included the standard performance parameters of sow and piglets, in particular the number of piglets (live and total born) per sow and litter, the sow's weight loss at farrowing and the piglet weight at birth, at weaning and after a rearing period of 42 days.

[0067] The feed used to feed the sows is shown in Table 1. The feeding trial began with the transition to the high-pregnancy feed on gestation day 80. Up until this point, all sows received a feed for low-pregnancy sows, which was identical for all sows (Table 1). Starting with entry into the farrowing pen on gestation day 110, the sows received a lactation feed (Table 1). To conduct the feeding trials according to the invention, guanidinoacetic acid was additionally mixed into the "high-pregnancy" and "lactation" feed rations in the appropriate amounts shown in Table 1.

[0068] Table 1: Ration composition and calculated ingredients of sow feed

[0069] Low pregnancy High pregnancy Lactation

[0070] Sugar (%) 0.00 0.00 5.00

[0071] Soybean oil (%) 4.00 0.00 3.00

[0072] Oat bran (%) 26.00 10.00 0.00

[0073] Corn (%) 16.05 0.00 48.16

[0074] Grain millet (%) 35.00 66.01 0.00

[0075] Biscuit flour (%) 0.00 0.00 10.00

[0076] Soybean meal (%) 15.00 19.60 29.10

[0077] Premix 2 (%) 0.20 0.50 0.80

[0078] Salt (%) 0.32 0.52 0.30

[0079] Calcium (%) 1.19 0.90 0.85

[0080] Dicalcium phosphate (%) 1.92 1.55 1.30

[0081] DL-methionine (%) 0.02 0.12 0.18

[0082] Lysine (%) 0.19 0.15 0.45

[0083] Threonine (%) 0.11 0.15 0.27

[0084] Tryptophan (%) 0.00 0.00 0.03 Valine (%) 0.00 0.00 0.06

[0085] Live yeast (%) 0.00 0.50 0.50

[0086] Total (%) 100.00 100.00 100.00

[0087] Calculated nutrient contents in feed

[0088] Metabolizable energy MJ / kg 12.55 12.36 14.45

[0089] Crude protein (%) 15.86 15.52 19.11

[0090] Verd. 1 Lysine (%) 0.63 0.75 1.20

[0091] Verd. 1 Met+Cys (%) 0.35 0.53 0.77

[0092] Verd. 1 Methionine (%) 0.25 0.30 0.50

[0093] Verd. 1 Tryptophan (%) 0.13 0.15 0.22

[0094] Verd. 1 Valine (%) 0.49 0.63 0.82

[0095] Verd. 1 Threonine (%) 0.47 0.60 0.84

[0096] Calcium (%) 1 ,01 0.80 0.76

[0097] Available phosphorus (%) 0.50 0.45 0.42

[0098] Sodium (%) 0.15 0.52 0.30

[0099] 1Precaecal digestible; % values ​​are weight percentages based on the total weight of the feed

[0100] 2 Vitamin and trace element mixture

[0101] The sows were given the appropriate feeds based on predefined feeding curves. Up to day 80 of gestation, the feed for low-pregnant sows and subsequently the feed for high-pregnant sows were fed at an average of 2.8 kg per sow per day. From day 90 onward, this amount was increased to 3.8 kg. The average amount was increased or decreased according to the sows' body condition. From farrowing onward, the sows were fed ad libitum, i.e., according to the sow's daily consumption, within the limits of feeding possibilities.

[0102] After weaning, i.e., on day 24 after farrowing, the sows' piglets were further observed. Of the piglets born in the trial, 1,200 animals were further divided into four observation groups according to the feed received by the respective sow. Each observation group thus consisted of 300 animals, each housed in 10 pens, for a total of 40 pens. The piglets were not fed any GAA-containing feed before or after weaning. The composition of the piglet feed is shown in Table 2 and corresponded to a four-phase piglet feeding program until the end of rearing, i.e., until the animals were transferred to the fattening pen. Table 2: Ration composition and calculated ingredients of the piglet feed

[0103] Pre-starter IP re-starter II Starter I Starter II

[0104] Day 24-30 Day 31-37 Day 38-51 Day 52-67

[0105] Corn (%) 23.06 31 .51 44.83 61 .55

[0106] Soybean oil (%) 1 .00 2.00 1 .50 2.50

[0107] Salt (%) 0.40 0.40 0.40 0.40

[0108] Soybean meal (%) 12.20 22.70 25.00 28.00

[0109] Sugar (%) 5.00 5.00 5.00 0.00

[0110] Biscuit flour (%) 16.00 12.00 8.00 0.00

[0111] Meat bone meal (%) 0.00 0.00 0.00 6.25

[0112] Feed acidity (%) 1.50 1.00 0.50 0.00

[0113] Antioxidant (%) 0.01 0.01 0.01 0.01

[0114] Cu Sulphate (%) 0.05 0.05 0.05 0.04

[0115] Choline (%) 0.09 0.08 0.07 0.04

[0116] DL-Methionine (%) 0.29 0.30 0.26 0.19

[0117] Sweetener (%) 0.02 0.02 0.02 0.01

[0118] Carbohydrase (%) 0.02 0.02 0.02 0.02

[0119] Phytase (%) 0.02 0.02 0.02 0.02

[0120] Dicalcium phosphate (%) 0.60 0.80 0.95 0.00

[0121] Milk powder (%) 20.00 7.50 2.50 0.00

[0122] L-Lysine (%) 0.56 0.51 0.47 0.40

[0123] L-Threonine (%) 0.34 0.32 0.26 0.20

[0124] L-Tryptophan (%) 0.15 0.12 0.07 0.04

[0125] Valine (%) 0.17 0.16 0.14 0.03

[0126] Blood plasma (%) 4.00 3.00 2.00 0.00

[0127] Mineral premix (%) 0.10 0.10 0.10 0.10

[0128] Vitamin premix (%) 0.07 0.06 0.05 0.04

[0129] Whey protein (%) 14.00 12.00 7.50 0.00

[0130] Filler (%) 2.241 2.241 1.701 1.151

[0131] Amoxicilin (%) 0.06 0.00 0.06 0.06

[0132] Doxycycline (%) 0.00 0.05 0.00 0.00

[0133] Tiamulin (%) 0.00 0.02 0.00 0.02

[0134] Total (%) 100.00 100.00 100.00 100.00

[0135] Calculated ingredients in feed

[0136] ME, MJ / kg feed 14.85 14.85 14.64 14.44

[0137] Crude protein (%) 19.30 19.30 19.30 22.20

[0138] Verd. 1Lysine (%) 1.45 1.55 1.50 1.45

[0139] Verd. 1 Met+Cys (%) 0.87 0.93 0.90 0.87

[0140] Verd. 1 Methionine (%) 0.52 0.60 0.57 0.50

[0141] Verd. 1 Tryptophan (%) 0.32 0.34 0.30 0.26

[0142] Verd. 1 Valine (%) 1 .02 1 .09 1 .05 1 .02

[0143] Verd. 1 Threonines (%) 1.02 1.09 1.05 0.99

[0144] Calcium (%) 0.60 0.60 0.60 0.65

[0145] Available phosphorus (%) 0.55 0.55 0.56 0.58

[0146] Sodium (%) 0.40 0.37 0.27 0.22

[0147] % values ​​are percentages by weight based on the total weight of the feed 1precaecal digestible Table 3 shows an overview of the observed parameters of the feeding trial. With regard to the number of live piglets born, only the sows in the group that received 0.24 wt% GAA in the feed gave birth to significantly more piglets (14.45 piglets) than the other three groups. After litter balancing to 13 piglets per sow within 24 hours of farrowing, the piglets in the 0.12 wt% group were the lightest (1.21 kg) and those in the control group the heaviest (1.36 kg). At weaning, the piglets of the sows that received 0.24 wt% and 0.36 wt% GAA reached the highest weaning weights of 6.06 kg and 6.22 kg respectively, the piglets in the control group weighed 5.81 kg and the piglets in the 0.12 wt% group were the lightest at 5.59 kg.

[0148] Three hundred piglets per sow group were housed in 10 pens after weaning, each according to the mother's GAA dosage, and further observed. However, the piglet feeds generally contained no GAA. It was found that all piglets from sows that received GAA from day 80 of gestation showed increased daily weight gain during the rearing period. On day 67 of life, the piglets in the control group were the lightest (24.46 kg). The piglets whose sows received 0.12 wt% GAA were slightly heavier (24.49 kg), and the piglets whose sows received 0.24 wt% and 0.36 wt% GAA were over 1.2 kg to 2.2 kg heavier than those in the control group, at 26.64 kg and 25.66 kg, respectively. Since the piglets whose sows received 0.12 wt% GAA were the lightest at weaning, they also showed increased daily weight gain after weaning in contrast to the control group.

[0149] Table 3: Performance data of sows and piglets in feeding trial 1

[0150] GAA dosage

[0151] 0.00% 0.12% 0.24% 0.36%

[0152] Sows (n) 40 40 40 40

[0153] Piglet performance during lactation

[0154] Live births per litter (n) 13.05 13.63 14.45 13.45

[0155] Birth weight (kg) 1 ,34 1 ,19 1 ,19 1 ,26

[0156] Number of piglets after litter balancing (n) 13 13 13 13

[0157] Piglet weight after litter balancing (kg) 1 ,36 1 ,21 1 ,22 1 ,30

[0158] Weaning weight piglets d 24 (kg) 5.81 5.59 6.06 6.22

[0159] Piglet performance after weaning

[0160] Number of piglets (n) 300 300 300 300

[0161] Number of bays 10 10 10 10

[0162] Daily gain (kg / d) 0.434 0.440 0.479 0.452

[0163] Final weight day 67 (kg) 24.46 24.49 26.64 25.66 Although feeding GAA to gilts from gestation day 80 onwards did not result in any demonstrated improvements in the gilts' performance, it did show an improvement in piglet weight gain during lactation when GAA was fed to the sows at 0.24 wt% or 0.36 wt%.

[0164] Particularly surprising was the improvement in piglet performance after weaning, even though the piglets themselves were not fed any GAA-containing feed. Thus, providing sows with GAA has positive effects on the piglets' growth potential, which is particularly evident after weaning.

[0165] Example 2: Feeding experiment 2

[0166] In a second study, a group of mixed-parity sows was fed a diet supplemented with 0.1% GAA by weight based on the total weight of the diet from entry into the AI ​​house (approximately 5 days before insemination) until weaning and compared with a group without GAA supplementation. The feed composition was switched from a diet for pregnant sows to a diet for lactating sows during the feeding study after farrowing (Table 4). Two consecutive sow groups were also observed in the production cycle. A total of 57 sows were examined: 27 sows in the control group without GAA supplementation and 30 sows in the group with 0.1% GAA supplementation.

[0167] The study parameters again included the standard performance parameters of sows and piglets. The piglets were observed for a further 42 days from weaning. Since the piglets were individually marked at birth, they were simply integrated into the farm's normal piglet rearing program from weaning onward and individually weighed again after the end of the rearing period. All piglets received the same commercially available piglet feed, which did not contain GAA, during rearing.

[0168] Table 4: Ration design of sow rations

[0169] Ingredient Pregnancy Lactating

[0170] Barley % 45.90 34.15

[0171] Wheat % 22.00 32.00

[0172] Soybean meal (CP48) % 6.0 8.50

[0173] Rapeseed meal % 7.1 7.70

[0174] Soybeans % 2.00

[0175] Linseed meal % 2.40

[0176] Wheat bran % 4.80 3.40

[0177] Sugar beet pulp % 4.00 1.25

[0178] Fruit pomace % 3.00

[0179] Alfalfa % 3.10 L-Lysine % 0.15 0.35

[0180] DL-Methionine % 0.08

[0181] L-Threonine % 0.12

[0182] L-tryptophan % 0.03

[0183] Calcium % 1.08 1.75

[0184] Monocalcium phosphate % 0.40 0.80

[0185] Sugar beet molasses % 0.50 1.00

[0186] Vegetable oil % 1 ,15 3,57

[0187] Salt % 0.42 0.50

[0188] Premix 2 (incl. choline) % 0.40 0.40

[0189] Treatment 1 : GAA % 0.00 0.00

[0190] Treatment 2: GAA % 0.10 0.10

[0191] Calculated ingredients in feed

[0192] Metabolizable energy MJ / kg 12.3 13.3

[0193] Crude protein % 14.1 16.1

[0194] Crude fiber % 6.68 4.73

[0195] Crude fat % 2.80 5.47

[0196] Total lysine (digestible) 1 % 0.75 (0.61) 1 .00 (0.86)

[0197] Methionine 1 % 0.23 (0.20) 0.34 (0.30)

[0198] Methionine / Cystine 1 % 0.52 (0.44) 0.66 (0.58)

[0199] Threonine 1 % 0.51 (0.38) 0.69 (0.56)

[0200] Tryptophan 1 % 0.18 (0.14) 0.23 (0.20)

[0201] Calcium % 0.69 0.92

[0202] Diluted phosphorus % 0.25 0.33

[0203] Sodium % 0.20 0.21

[0204] Choline % 0.13 0.13

[0205] % values ​​are percentages by weight based on the total weight of the feed

[0206] 1) The values ​​indicate the absolute weight percentage or, in brackets, the digestible weight percentage in the feed.

[0207] 2) Gehalte pro kg Premix: 2.950.000 I.E. Vitamin A; 300.000 I.E. Vitamin D3; 33.000 mg Vitamin E; 356,7 mg Vitamin K3; 626,7 Vitamin B1; 2.167 mg Vitamin B2; 12.599 mg Niacin; 1 ,7940 mg Vitamin B6; 9,917 pg Vitamin B12; 133 mg Biotin; 230.413,2 Cholinchlorid; 5.417 mg d-Pantothensäure; 900 mg Folsäure; 33.356 mg Zn; 53.503 mg Fe; 22.743 mg Mn; 4.513 mg Cu; 100 mg Se; 450 mg lod; 430 pg Cobald.

[0208] After the piglets of the sows in both groups developed almost identically from birth to weaning (weaning weight for the 0.0% GAA group: 7.2 kg, for the 0.1% GAA group: 7.1 kg; due to their higher birth weight, slightly lower weight gains for the piglets in the 0.1% GAA group), the same effect as described above occurred after weaning. The piglets in the 0.1% GAA group, which also never received feed supplemented with GAA in this experiment, were already around 300 g heavier than those in the control group 14 days after weaning and, at the end of the observation period on day 77 of life, 42 days after weaning, were 1.01 kg heavier than the animals of the sows in the 0.0% GAA group. Table 5: Summary of the weight development of the piglets in feeding experiment 2

[0209] Treatment 0.0% GAA 0.1% GAA

[0210] Number of sows (n) 27 30

[0211] Number of piglets dO (n) 398 423

[0212] Piglet weight dO (kg) 1 ,264 1 ,323

[0213] Number of piglets d28 (n) 340 340

[0214] Weight of piglet d28 (kg) 7.198 7.131

[0215] Piglet weight gain during lactation (kg) 5,860 5,737

[0216] Number of piglets per day of life 42 (n) 330 326

[0217] Weight piglet d42 (kg) 8.242 8.55

[0218] Number of piglets d77 (n) 325 317

[0219] Weight piglet d77 (kg) 24,649 25,656

[0220] Feeding 0.1% GAA from the beginning of the sow's production cycle, i.e., at insemination, until weaning had similar effects on the piglets' growth potential as the application of higher dosages (0.12% to 0.36%) from gestation day 80. The weight development of the piglets after weaning can therefore be positively influenced by both a relatively short supplementation of GAA to the sow's feed with higher dosages and a long-term application.

Claims

Patent claims 1. Use of a feed additive comprising guanidinoacetic acid in the feeding of pregnant sows to improve the weight gain of piglets during the rearing period.

2. Use of a feed additive according to claim 1, characterized in that the feed additive is administered to pregnant sows to improve the weight gain of piglets, wherein the improved weight gain of the piglets takes place in a period starting from day 14 to 42 after the birth of the piglets and / or in particular starting with the weaning of the piglets, until day 40 to 120 after the birth of the piglets.

3. Use of a feed additive according to one of claims 1 to 2, characterized in that the guanidinoacetic acid contained in the feed additive is used in an amount in the range of 0.02 wt.% to 1 wt.% based on the total weight of the feed.

4. Use of a feed additive according to one of claims 1 to 3, characterized in that the feed additive is fed from the insemination of the sows until farrowing for a period of more than 50 days, wherein the feed contains guanidinoacetic acid in an amount in the range of 0.05 wt% to 0.25 wt% based on the total weight of the feed.

5. Use of a feed additive according to one of claims 1 to 3, characterized in that the feed additive is fed for a period of at least 20 to 50 days from day 50 of pregnancy until farrowing, wherein the feed contains guanidinoacetic acid in an amount in the range of 0.15 wt% to 0.4 wt% based on the total weight of the feed.

6. Use of a feed additive according to any one of claims 1 to 5, characterized in that the feed additive is also administered to the sows during lactation.

7. Use of a feed additive according to any one of claims 1 to 6, characterized in that no guanidinoacetic acid is administered to the piglets during the rearing phase.

8. Use of a feed additive according to any one of claims 1 to 7, characterized in that the weight gain of the piglets on day 67 or on day 77 after the birth of the piglets is more than 4% higher than the weight gain of piglets reared under the same conditions but whose sows were not administered guanidinoacetic acid during pregnancy.

9. Use of guanidinoacetic acid in the feeding of pregnant sows to improve the weight gain of piglets during the rearing period.

10. Use of guanidinoacetic acid according to claim 9, characterized in that the improvement in the weight gain of piglets takes place in a period starting from day 14 to 42 after the birth of the piglets, in particular starting with the weaning of the piglets, until day 50 to 120 after the birth of the piglets.

11. A method for improving the weight gain of piglets during the rearing period, comprising administering guanidinoacetic acid to pregnant sows during feeding.

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