Low-methionine poultry feed and application thereof

Abstract

The invention relates to the technical field of feeds, and discloses a low-methionine poultry feed and application thereof. The content of methionine in the low-methionine poultry feed is 0.34 wt% to 0.38 wt%. The feed comprises the following components: a basic ration and a functional additive, the functional additive comprises betaine hydrochloride and a pH buffer agent. According to the low-methionine poultry feed provided by the invention, the content of methionine is only 0.34-0.38 wt% and is about 60-70% of the nutritional demand, the low-methionine poultry feed belongs to a severe methionine deficiency feed, 18.87% of methionine can be replaced by adding betaine hydrochloride, the methionine demand of poultry is ensured, the growth performance and the slaughter performance are improved, and the feed cost is reduced; the influence of the addition amount of the betaine on the growth performance and the slaughter performance shows a nonlinear dosage effect, so that the pH buffer agent needs to be added synchronously, and the situation that the methyl donor is overloaded easily due to excessive addition of the betaine when a buffer system is lacked is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of feed, in particular to a low-methionine poultry feed and application thereof. Background Art

[0002] Methionine, the first limiting amino acid in poultry nutrition, presents a significant nutritional paradox due to its dual metabolic properties. At the protein synthesis level, methionine directly drives muscle protein synthesis by activating the mTOR signaling pathway, promoting ribosome assembly. mTOR is the "master switch" for muscle growth, and methionine deficiency inhibits this pathway, resulting in decreased muscle deposition efficiency. At the methyl metabolism level, methionine is converted into a universal methyl donor via the S-adenosylmethionine (SAM) cycle, participating in epigenetic regulation through DNA methylation (mediated by DNMTs) and phospholipid metabolism.

[0003] Metabolic flux analysis shows that when poultry enter their rapid growth phase (22-42 days of age), approximately 38% of methionine molecules are preferentially diverted to the methyl donor pathway, resulting in a 17%-23% decrease in the effective utilization rate for muscle protein synthesis and a resulting resource competition. Although farming aims to utilize more methionine for muscle growth, the methyl donor function is a physiological necessity, making it difficult to balance methionine resource allocation in traditional diet designs.

[0004] The metabolic competition effect of methionine may be particularly prominent in the setting of severe methionine deficiency (<70% of requirement). However, current mainstream research focuses on mild methionine deficiency (70-80% of requirement), and lacks understanding of the mechanism of methyl homeostasis imbalance in the setting of severe methionine deficiency (<70%). In addition, existing betaine replacement studies mostly use a linear dose design and do not construct a synergistic system with a buffer system (such as sodium bicarbonate). Experimental evidence has shown that in the absence of a buffer system, excessive betaine (≥2.5g / kg) will cause methyl donor overload, causing the S-adenosylmethionine and S-adenosylhomocysteine (SAM / SAH) ratio to decrease by 41%, while too low SAM / SAH will inhibit the activity of key enzymes. Summary of the Invention

[0005] The present invention aims to solve at least one of the above-mentioned technical problems in the prior art. To this end, one of the objects of the present invention is to provide a low-methionine poultry feed.

[0006] A second object of the present invention is to provide an application of the low-methionine poultry feed.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides a low-methionine poultry feed, wherein the methionine content of the feed is 0.34wt%-0.38wt%; the components of the feed include a basic diet and a functional additive; the functional additive includes betaine hydrochloride and a pH buffer.

[0009] In some embodiments of the present invention, the methionine content of the feed is 60-70% of the nutritional requirement, which is a severe methionine-deficient feed.

[0010] In some embodiments of the present invention, the content of betaine hydrochloride in the feed is 0.15%-0.30% by mass; and the content of pH buffer is 0.20%-0.40%.

[0011] In some preferred embodiments of the present invention, the content of betaine hydrochloride in the feed is 0.15%-0.30% by mass; and the content of pH buffer is 0.30%-0.36%.

[0012] In some embodiments of the present invention, the mass ratio of the betaine hydrochloride to the pH buffer is 1:(1.2-2).

[0013] In some embodiments of the present invention, the pH buffer is selected from at least one of sodium bicarbonate, potassium carbonate, and sodium citrate.

[0014] In some preferred embodiments of the present invention, the pH buffer is sodium bicarbonate.

[0015] In the present invention, sodium bicarbonate (NaHCO3) is preferably used as a pH buffer, and its core role in the feed formula for severe methionine deficiency is to regulate electrolyte balance (Ecq = 435*Na + +256*K + -282*Cl - ), and synergizes with betaine hydrochloride to maintain methyl metabolism homeostasis.

[0016] In some embodiments of the present invention, the basal diet comprises the following components: corn, flour, soybean meal, corn gluten meal, cottonseed meal, sunflower kernel meal, soybean oil, rock flour, calcium hydrogen phosphate, sodium chloride, L-lysine and premix.

[0017] In some embodiments of the present invention, the feed includes the following components, calculated by mass percentage: 0.15%-0.30% betaine hydrochloride, 0.20%-0.40% pH buffer, 50.0%-52.0% corn, 5.0%-7.0% flour, 25.0%-27.0% soybean meal, 2.0%-4.0% corn gluten meal, 1.0%-3.0% cottonseed meal, 1.0%-3.0% sunflower kernel meal, 6.0%-8.0% soybean oil, 0.4%-0.6% stone powder, 1.0%-1.5% calcium hydrogen phosphate, 0.2%-0.5% sodium chloride, 0.6%-0.9% L-lysine and 0.8%-1.2% premix.

[0018] In some preferred embodiments of the present invention, the feed comprises the following components, calculated by mass percentage: 0.15%-0.30% betaine hydrochloride, 0.30%-0.36% pH buffer, 50.0%-51.0% corn, 5.5%-6.0% flour, 25.0%-26.0% soybean meal, 2.5%-3.0% corn gluten meal, 2.0%-2.5% cottonseed meal, 2.0%-2.5% sunflower kernel meal, 7.0%-7.5% soybean oil, 0.4%-0.5% stone powder, 1.0%-1.2% calcium hydrogen phosphate, 0.2%-0.3% sodium chloride, 0.6%-0.8% L-lysine and 0.8%-1.0% premix.

[0019] In some embodiments of the present invention, the premix comprises the following components: vitamin A, vitamin E, vitamin D3, vitamin K3, thiamine, riboflavin, pyridoxine, vitamin B 12 , calcium pantothenate, niacin, folic acid, D-biotin, choline chloride, copper sulfate pentahydrate, iron sulfate heptahydrate, zinc sulfate, manganese sulfate monohydrate, sodium selenite, and potassium iodide.

[0020] In some embodiments of the present invention, the premix comprises the following components: vitamin A 9000-11000 IU / kg, vitamin E 30-40 mg / kg, vitamin D3 3500-4000 IU / kg, vitamin K3 2-6 mg / kg, thiamine 4-8 mg / kg, riboflavin 1-3 mg / kg, pyridoxine 2-6 mg / kg, vitamin B 120.01-0.05mg / kg, calcium pantothenate 15-25mg / kg, niacin 80-90mg / kg, folic acid 1-4mg / kg, D-biotin 0.1-0.3mg / kg, choline chloride 1600-2000mg / kg, copper sulfate pentahydrate 1-5mg / kg, iron sulfate heptahydrate 70-90mg / kg, zinc sulfate 40-60mg / kg, manganese sulfate monohydrate 90-110mg / kg, sodium selenite 0.05-0.2mg / kg and potassium iodide 0.1-0.5mg / kg.

[0021] In some preferred embodiments of the present invention, the premix comprises the following components: vitamin A 9500-10500 IU / kg, vitamin E 35-40 mg / kg, vitamin D3 3500-3800 IU / kg, vitamin K3 3-5 mg / kg, thiamine 5-7 mg / kg, riboflavin 1.5-2.5 mg / kg, pyridoxine 3-5 mg / kg, vitamin B 12 0.02-0.04mg / kg, calcium pantothenate 18-23mg / kg, niacin 83-87mg / kg, folic acid 2-3mg / kg, D-biotin 0.1-0.2mg / kg, choline chloride 1700-1900mg / kg, copper sulfate pentahydrate 2-3mg / kg, iron sulfate heptahydrate 75-85mg / kg, zinc sulfate 45-55mg / kg, manganese sulfate monohydrate 95-105mg / kg, sodium selenite 0.05-0.15mg / kg and potassium iodide 0.2-0.4mg / kg.

[0022] The second aspect of the present invention provides use of the low-methionine poultry feed described in the first aspect of the present invention in broiler chicken farming.

[0023] In some embodiments of the present invention, the broiler chickens are 22-42 days old broiler chickens.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1) The low-methionine poultry feed provided by the present invention has a methionine content of only 0.34wt%-0.38wt%, which is approximately 60-70% of the nutritional requirement and is a severely methionine-deficient feed. By adding betaine hydrochloride, 18.87% of the methionine can be replaced, thereby ensuring the methionine requirement of poultry while improving growth performance and slaughter performance and reducing feed costs. However, the effect of betaine addition on growth performance and slaughter performance shows a nonlinear dosage effect, so it is necessary to simultaneously add a pH buffer to balance electrolyte levels. By controlling the mass ratio of the two, excessive addition of betaine in the absence of a buffer system can be avoided, which can easily cause methyl donor overload.

[0026] 2) The low-methionine poultry feed provided by the present invention is suitable for breeding broiler chickens aged 22-42 days, and can significantly improve the decline in growth performance and slaughter performance, liver metabolic disorders, etc. caused by methionine deficiency, and reduce breeding costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The expression of genes related to one-carbon metabolism in the liver of broiler chickens aged 22-42 days in each group in Example 1;

[0028] Figure 2 The expression of DNA methylation-related genes in the liver of broiler chickens of each group aged 22-42 days in Example 1 is shown. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below by way of specific examples. Unless otherwise specified, the raw materials, reagents, or devices used in the examples are all commercially available or can be obtained by conventional methods. Unless otherwise specified, all experiments or testing methods are conventional methods in the art.

[0030] Example 1

[0031] This example investigates the effects of betaine hydrochloride and a buffer on growth performance, slaughter performance, serum methionine cycle-related products, and liver biochemical indicators in broiler chickens aged 22-42 days. The method is as follows:

[0032] 480 22-day-old Yisheng 909 broiler roosters of similar weight were selected and set up as a positive control group (nutritional requirement-satisfying diet, methionine content of 0.53wt%), a negative control group (methionine deficiency, content of 0.34wt%), a betaine supplemented group 1 (negative control group + 1500mg / kg betaine hydrochloride), and a betaine supplemented group 2 (negative control group + 3000mg / kg betaine hydrochloride). Each group was treated with 6 replicates, with 20 birds in each replicate. The experimental period was 22-42 days of age, a total of 21 days. During the experimental period, the birds had free access to food and water and were kept according to conventional feeding management. The composition of the poultry feed fed to each group is shown in Table 1, and the nutritional level of the poultry feed is shown in Table 2.

[0033] Table 1 Composition of poultry feed in each group in Example 1

[0034] Component (g / kg) Positive control group Negative control group Betaine supplementation group 1 Betaine supplementation group 2 corn 516.7 516.7 505.7 502.7 flour 50 50 60 60 soybean meal 255 257 255.5 255.5 corn gluten meal 30 30 30 30 cottonseed meal 20 20 20 20 Sunflower seed kernel meal 20 20 20 20 soybean oil 70 70 70 71 Betaine hydrochloride 0 0 1.5 3 Stone powder 4.8 4.8 4.8 4.8 Calcium hydrogen phosphate 10.5 10.5 10.5 10.5 Sodium chloride 2 2 2 2 Sodium bicarbonate 2 2 3 3.6 DL-methionine 2 0 0 0 L-Lysine 7 7 7 7 Premix 10 10 10 10

[0035] The composition of the premix is as follows: Vitamin A 10000IU / kg, Vitamin E 36mg / kg, Vitamin D3 3750IU / kg, Vitamin K3 4.0mg / kg, Thiamine 6.0mg / kg, Riboflavin 2.0mg / kg, Pyridoxine 4.0mg / kg, Vitamin B 120.025 mg / kg, calcium pantothenate 20 mg / kg, niacin 85 mg / kg, folic acid 2.5 mg / kg, D-biotin 0.15 mg / kg, choline chloride 1800 mg / kg, copper sulfate pentahydrate 2.5 mg / kg, iron sulfate heptahydrate 80 mg / kg, zinc sulfate 50 mg / kg, manganese sulfate monohydrate 100 mg / kg, sodium selenite 0.10 mg / kg and potassium iodide 0.35 mg / kg.

[0036] Table 2 Nutritional levels of poultry feed fed to each group in Example 1

[0037] project Positive control group Negative control group Betaine supplementation group 1 Betaine supplementation group 2 <![CDATA[Metabolizable energy 1 (kcal / kg)]]> 3220 3225 3219 3218 <![CDATA[Crude protein 2 (%)]]> 19.73 19.70 19.69 19.66 <![CDATA[Calcium 2 (%)]]> 0.60 0.60 0.60 0.60 <![CDATA[Total Phosphorus 2 (%)]]> 0.55 0.55 0.55 0.55 <![CDATA[Non - phytic acid phosphorus 1 (%)]]> 0.32 0.32 0.32 0.32 <![CDATA[Lysine 1 (%)]]> 1.30 1.30 1.30 1.30 <![CDATA[Methionine 1 (%)]]> 0.53 0.34 0.34 0.34 <![CDATA[Egg + Cystine 1 (%)]]> 0.88 0.69 0.69 0.69

[0038] in, 1 The values are calculated values. 2 The values are measured.

[0039] As shown in Tables 1 and 2, the positive control group received an additional 2g / kg of DL-methionine, resulting in a methionine content of 0.53wt% in the feed, meeting nutritional requirements. The negative control group, which did not receive DL-methionine, had its feed supplied solely by the basal diet, with a methionine content of 0.34wt%, approximately 64% of that in the positive control group, indicating severe methionine deficiency. Betaine-supplemented groups 1 and 2, supplemented with 1.5g / kg and 3.0g / kg of betaine hydrochloride, respectively, in addition to the negative control group, still maintained a methionine content of 0.34wt%, indicating that betaine hydrochloride only served as a methyl donor and did not contribute methionine. Furthermore, the poultry feeds in the positive and negative control groups, as well as betaine-supplemented groups 1 and 2, had similar or similar nutritional levels of metabolizable energy, crude protein, and lysine, eliminating the possibility that other factors may have influenced the experimental results.

[0040] Table 3 Growth performance of broiler chickens aged 22-42 days in each group in Example 1

[0041]

[0042] Among them, the numbers without the same superscript letters in the same column indicate significant differences (p<0.05).

[0043] Table 3 shows the growth performance of broiler chickens aged 22-42 days in each group in Example 1. As can be seen from Table 3, the final weight, daily weight gain and daily feed intake of broiler chickens aged 22-42 days in the positive control group were significantly higher than those in the negative control group and betaine supplemented groups 1 and 2, and the feed-to-meat ratio was significantly lower than that in the other three groups, indicating that severe methionine deficiency (0.34%) significantly reduced weight gain and feed utilization (increased feed-to-meat ratio), proving that methionine is a key amino acid for muscle synthesis, and its deficiency will lead to reduced protein deposition and stunted growth. Betaine supplemented group 1 was supplemented with betaine hydrochloride and buffer at a mass ratio of 1:2. It can be seen that the feed-to-meat ratio was significantly reduced compared with the negative control group, but was still higher than that of the positive control group, indicating that betaine can partially replace the methyl donor function of methionine, but cannot completely make up for the protein synthesis function; while betaine supplemented group 2 was supplemented with betaine hydrochloride and buffer at a mass ratio of 1:1.2, which had no obvious effect on the feed-to-meat ratio, indicating that excessive betaine may be ineffective due to methyl donor overload (SAH accumulation). The effect of betaine addition on growth performance showed a nonlinear dose effect.

[0044] Table 4 Slaughter performance of 22-42 day old broiler chickens in each group in Example 1

[0045]

[0046] Among them, the numbers without the same superscript letters in the same column indicate significant differences (p<0.05).

[0047] The calculation of slaughter performance refers to the agricultural industry standard "Poultry Production Performance Terminology and Measurement Calculation Method" (NY / T823-2020), specifically:

[0048] 1) Carcass weight: The weight of the poultry after bleeding, removal of feathers, foot cuticles, toe shells and beak shells;

[0049] 2) Eviscerated weight: the weight of the carcass after removing the trachea, esophagus, crop, intestines, spleen, pancreas, gallbladder, reproductive organs, stomach contents and corneum;

[0050] 3) Eviscerated weight: half eviscerated weight minus the weight of the heart, liver, proventriculus, gizzard, lungs and abdominal fat (for fast-moving broilers, the head and feet must also be removed):

[0051] 4) Eviscerated rate is the percentage of eviscerated weight to ante-slaughter weight, eviscerated rate = eviscerated weight / ante-slaughter weight * 100%;

[0052] 5) Eviscerated rate is the percentage of eviscerated weight to ante-slaughter weight, eviscerated rate = eviscerated weight / ante-slaughter weight * 100%;

[0053] 6) Chest muscle ratio is the percentage of chest muscle weight on both sides to total eviscerated weight. Chest muscle ratio = chest muscle weight on both sides / total eviscerated weight * 100%;

[0054] 7) Leg muscle rate is the percentage of leg muscle weight on both sides to total eviscerated weight, leg muscle rate = leg muscle weight on both sides / total eviscerated weight * 100%;

[0055] 8) Abdominal fat rate is the percentage of abdominal fat weight to the sum of total eviscerated weight and abdominal fat weight. Abdominal fat rate = abdominal fat weight / (total eviscerated weight + abdominal fat weight)*100%.

[0056] Table 4 shows the slaughter performance of broiler chickens aged 22-42 days in each group in Example 1. As shown in Table 4, the evisceration rate of the positive control group was significantly higher than that of the negative control group and betaine supplemented group 2, and the breast muscle rate was significantly higher than that of the other groups, indicating that methionine is a key substrate for muscle protein synthesis and muscle deposition is reduced when it is deficient; the abdominal fat rate of the negative control group was significantly higher than that of the other groups, indicating that methionine is involved in fat metabolism and energy is diverted to fat deposition when it is deficient; compared with the negative control group, the breast muscle rate of betaine supplemented groups 1 and 2 increased by 1.59% and 1.38%, respectively, and the abdominal fat rate decreased by 0.49% and 0. .52%, indicating that betaine can promote carnitine synthesis (reduce abdominal fat) and partially support muscle growth by providing methyl groups, while sodium bicarbonate can regulate electrolyte balance and prevent methyl donor overload (SAM / SAH imbalance); the slaughter performance of betaine-supplemented group 2 was not significantly different from that of betaine-supplemented group 1, but the eviscerated rate, half-eviscerated rate and breast muscle rate all showed a downward trend, indicating that the mass ratio of betaine hydrochloride to sodium bicarbonate was too large, that is, the effect of betaine addition on slaughter performance showed a nonlinear dose effect, and there was no additional benefit when betaine hydrochloride was added in excess.

[0057] Table 5 Serum methionine cycle-related products of broiler chickens aged 22-42 days in each group in Example 1

[0058] project SAM (ng / mL) SAH (ng / mL) SAM / SAH Hcy (ng / mL) Positive control group <![CDATA[20.55 a ]]> <![CDATA[8.24 c ]]> <![CDATA[2.50 a ]]> <![CDATA[21.68 a ]]> Negative control group <![CDATA[9.96 c ]]> <![CDATA[14.60 a ]]> <![CDATA[0.68 c ]]> <![CDATA[11.18 c ]]> Betaine supplementation group 1 <![CDATA[16.54 b ]]> <![CDATA[10.48 b ]]> <![CDATA[1.58 b ]]> <![CDATA[17.52 b ]]> Betaine supplementation group 2 <![CDATA[11.98 c ]]> <![CDATA[14.88 a ]]> <![CDATA[0.81 c ]]> <![CDATA[13.21 c ]]> Standard error of the mean (SEM) 0.65 0.37 0.10 0.63 p-value ＜0.001 ＜0.001 ＜0.001 ＜0.001

[0059] Wherein, SAM refers to S-adenosylmethionine; SAH refers to S-adenosylhomocysteine; Hcy refers to homocysteine; the same letters in the same column indicate significant differences (p < 0.05).

[0060] Table 5 shows serum methionine cycle-related products of 22-42-day-old broiler chickens in each group of Example 1. Among them, SAM (S-adenosylmethionine) is a universal methyl donor that can participate in DNA / protein methylation, phospholipid synthesis, etc.; SAH (S-adenosylhomocysteine) is a byproduct of the methylation reaction, and high SAH will inhibit methyltransferase activity; the SAM / SAH ratio reflects the methylation potential, and a low ratio indicates that methylation metabolism is blocked; Hcy (homocysteine) is an intermediate product of methionine metabolism, and high Hcy indicates a methylation cycle disorder. As shown in Table 5, the SAM, SAM / SAH ratio, and Hcy of the positive control group were significantly higher than those of the other groups, while SAH was significantly lower than those of the other groups, indicating that in the negative control group and betaine supplementation groups 1 and 2, methionine deficiency leads to insufficient methyl donors, inhibited methylation reactions, and blocked methionine metabolic flow. Compared with the negative control group, betaine-supplemented groups 1 and 2 showed increases in SAM, the SAM / SAH ratio, and Hcy, while SAH decreased. This suggests that betaine remethylates Hcy to methionine via the BHMT pathway, alleviating methyl donor deficiency. However, this approach cannot completely replace methionine's protein synthesis function. Compared with betaine-supplemented group 2, betaine-supplemented group 1 demonstrated a greater ability to increase SAM, decrease SAH, and improve the SAM / SAH ratio, indicating that the addition of betaine hydrochloride to buffer at a mass ratio of 1:2 is more effective.

[0061] Table 6 Liver biochemical indicators of broiler chickens aged 22-42 days in each group in Example 1

[0062]

[0063] BHMT refers to betaine homocysteine methyltransferase; CβS refers to cystathionine β-synthase; DNMT1 refers to DNA methyltransferase 1; DNMT3a refers to DNA methyltransferase 3a; DNMT3b refers to DNA methyltransferase 3b; GNMT refers to glycine N-methyltransferase; the same letters in the same column indicate significant differences (p < 0.05).

[0064] Table 6 shows the liver biochemical parameters of broiler chickens aged 22-42 days in each group of Example 1. Among them, BHMT catalyzes the conversion of Hcy to methionine by donating a methyl group from betaine; DNMT3a / DNMT3b catalyze DNA methylation, affecting gene expression regulation; CβS catalyzes the transsulfurization pathway of Hcy to produce cysteine; free carnitine participates in fatty acid oxidation, and creatine is an energy metabolism molecule. As shown in Table 6, compared with the positive control group, the negative control group and betaine-supplemented groups 1 and 2 showed compensatory increases in the activities of enzymes such as BHMT, DNMT3a, DNMT3b, and CβS, and accumulation of free carnitine and creatine, indicating that methionine deficiency leads to liver metabolic disorders. Compared with betaine supplementation group 2, the compensatory increase in the activities of enzymes such as BHMT, DNMT3a, DNMT3b, and CβS in betaine supplementation group 1 was lower and lower than that in the negative control group, indicating that the addition of betaine hydrochloride and buffer at a mass ratio of 1:2 can reduce the compensatory demand of enzymes such as BHMT and DNMTs by providing methyl groups, improve the methylation cycle, and reduce the pressure of the transsulfurization pathway (CβS) by lowering Hcy levels.

[0065] Figure 1 The expression of genes related to one-carbon metabolism in the liver of broiler chickens aged 22-42 days in each group in Example 1 is shown, among which: Figure 1 (a) is the relative expression level of liver methionine synthase (MS), Figure 1 (b) is the relative expression of liver adenosine homocysteinease (AHCYL), Figure 1 (c) is the relative expression level of liver betaine homocysteine methyltransferase (BHMT), Figure 1 (d) is the relative expression of methylenetetrahydrofolate reductase (MTHFR) in the liver. Figure 1 (e) is the relative expression level of liver methionine adenosyltransferase 2b (MAT2b), Figure 1 (f) is the relative expression level of cystathionine β-synthase (CβS) in the liver, and * indicates significant difference (p < 0.05). Figure 1 It can be seen that compared with the positive control group, the expression of all genes in the negative control group was significantly downregulated, indicating that severe methionine deficiency (0.34%) would inhibit the activity of key enzymes in liver one-carbon metabolism; betaine supplementation groups 1 and 2 could partially alleviate the downregulation of gene expression, but it was still significantly lower than the positive control group, indicating that betaine hydrochloride can partially compensate for the negative impact of methionine deficiency on one-carbon metabolism by providing methyl donors, but cannot completely replace the function of methionine.

[0066] Figure 2 The expression of DNA methylation-related genes in the liver of broiler chickens aged 22-42 days in each group in Example 1, wherein: Figure 2 (a) is the relative expression level of liver DNA methyltransferase-1 (DNMT1), Figure 2 (b) is the relative expression of liver DNA methyltransferase-3a (DNMT3a), Figure 2 (c) is the relative expression level of liver DNA methyltransferase-3b (DNMT3b), Figure 2 (d) is the relative expression level of glycine-N-methyltransferase (GNMT) in the liver, and * indicates significant difference (p < 0.05). Figure 2 It can be seen that compared with the positive control group, the expression of DNMT3a, DNMT3b and GNMT was significantly upregulated in the negative control group, which is speculated to be related to the compensatory response caused by methyl homeostasis imbalance; the overexpression of DNMT3a, DNMT3b and GNMT was significantly reduced in betaine supplementation groups 1 and 2, but did not return to the level of the positive control group; there was no significant change in DNMT1 expression, indicating that it may not be directly affected by methionine deficiency or betaine; the above results indicate that betaine can partially correct DNA methylation abnormalities caused by methionine deficiency, but high doses (3000 mg / kg) did not show additional advantages.

[0067] In summary, betaine can significantly improve the growth performance and slaughter performance of poultry fed a diet with severe methionine deficiency (methionine requirement of 64%), but it is still significantly lower than the control group. This may be because betaine can only replace the methyl donor capacity of methionine, but cannot replace its special physiological functions such as participation in protein synthesis. Studies have shown that in the late growth period, betaine can partially replace the physiological function of methionine under moderate methionine deficiency (methionine content is 76% of the requirement) and significantly improve the growth performance of broilers aged 22-42 days. However, in this experiment, the growth performance of the positive control group at 22-42 days of age was significantly better than that of the other groups. This may be because the methionine content in the methionine-deficient group set up in this experiment was only 64% of the positive control group (0.34% vs. 0.53%), which is lower than the minimum requirement for methionine to exert its special physiological functions and is considered to be severely deficient.

[0068] Example 2

[0069] This example explores the maximum value of methionine that can be substituted by betaine hydrochloride, and the method is as follows:

[0070] 720 22-day-old Yisheng 909 broiler roosters of similar weight were selected. A positive control group (methionine content 0.53wt%) was set up, and a low-methionine diet + excess betaine was used as a negative control group (0.33wt% methionine + 3000mg / kg betaine). Methionine was then added in a gradient on the basis of the negative control group (negative control group + 0.05wt%, 0.10wt%, 0.15wt% or 0.20wt% methionine). A total of 6 treatment groups were set up, each with 6 replicates and 20 chickens per replicate. The experimental period was 22-42 days of age, a total of 21 days. During the experiment, the chickens had free access to food and water, and were kept according to routine feeding management.

[0071] Table 7 Growth performance of broiler chickens aged 22-42 days in each group in Example 2

[0072] Grouping Initial weight (kg) Final weight (kg) Daily weight gain (g / d) Daily feed intake (g / d) Feed-to-meat ratio Control group (0.53wt% methionine) 0.45 <![CDATA[1.69 a ]]> <![CDATA[51.52 a ]]> 96.60 <![CDATA[1.87 c ]]> 0.33wt% methionine + 3000mg / kg betaine 0.46 <![CDATA[1.60 b ]]> <![CDATA[47.47 b ]]> 95.70 <![CDATA[2.01 a ]]> 0.38wt% methionine + 3000mg / kg betaine 0.46 <![CDATA[1.63 b ]]> <![CDATA[49.00 b ]]> 96.42 <![CDATA[1.97 b ]]> 0.43wt% methionine + 3000mg / kg betaine 0.46 <![CDATA[1.68 a ]]> <![CDATA[51.03 a ]]> 97.47 <![CDATA[1.88 c ]]> 0.48wt% methionine + 3000mg / kg betaine 0.46 <![CDATA[1.73 a ]]> <![CDATA[52.77 a ]]> 98.38 <![CDATA[1.86 c ]]> 0.53wt% methionine + 3000mg / kg betaine 0.45 <![CDATA[1.71 a ]]> <![CDATA[52.42 a ]]> 96.84 <![CDATA[1.85 c ]]> Standard error of the mean (SEM) 0.01 0.01 0.58 0.84 0.01 p-value 0.3389 ＜0.001 ＜0.001 0.3321 ＜0.001

[0073] Among them, the numbers without the same superscript letters in the same column indicate significant differences (p<0.05).

[0074] Table 7 shows the growth performance of broiler chickens aged 22-42 days in each group in Example 2. As shown in Table 7, the final weight, daily weight gain, daily feed intake and feed-to-meat ratio of the 42-day-old broiler chickens in the positive control group were significantly higher than those in the negative control group (0.33wt% methionine + 3000mg / kg betaine); the growth performance of the 42-day-old broiler chickens in the 0.38wt% methionine + 3000mg / kg betaine group was better than that of the negative control group, but still significantly lower than that of the positive control group; when the total amount of methionine was increased from 0. When the methionine content was increased from 33wt% to 0.43wt% (i.e., 0.10wt% methionine was supplemented), the growth performance (final weight, daily weight gain, and feed-to-meat ratio) of broiler chickens in the 0.43wt% methionine + 3000mg / kg betaine group was not significantly different from that of the positive control group, indicating that betaine can replace 18.87% of the methionine requirement; when the methionine supplementation amount exceeded 0.43wt%, the performance improvement tended to be flat, indicating that the replacement of betaine in the methyl donor function has been close to saturation.

[0075] The low-methionine poultry feed provided by the present invention has a methionine content of 0.34wt%-0.38wt%. Referring to the "Nutritional Requirements of Poultry" published by the NRC and the recommended methionine amount provided in the "Safe Use of Feed Additives Specifications", broiler chickens require about 0.5wt% at the chick stage. When 0.53wt% is used as the nutritional requirement standard in this application, a methionine content of 0.34wt%-0.38wt% belongs to the severe deficiency range. It has been verified that in the case of severe deficiency, 18.87% of methionine can be replaced by betaine, which can not only meet the methionine requirements of broiler chickens and growth performance, but also reduce feed costs.

Claims

1. A low methionine poultry feed, characterized in that: The methionine content of the feed is 0.34wt%-0.38wt%; the components of the feed include a basic diet and functional additives; the functional additives include betaine hydrochloride and a pH buffer.

2. The low methionine poultry feed according to claim 1, characterized in that Calculated by mass percentage, the content of betaine hydrochloride in the feed is 0.15%-0.30%; the content of pH buffer is 0.20%-0.40%.

3. The low methionine poultry feed according to claim 2, characterized in that The mass ratio of the betaine hydrochloride to the pH buffer is 1:(1.2-2).

4. The low methionine poultry feed according to any one of claims 1 to 3, characterized in that The pH buffer is selected from at least one of sodium bicarbonate, potassium carbonate and sodium citrate.

5. The low methionine poultry feed according to claim 1, characterized in that The basal diet includes the following components: Corn, flour, soybean meal, corn gluten meal, cottonseed meal, sunflower kernel meal, soybean oil, rock flour, calcium phosphate, sodium chloride, L-lysine and premix.

6. The low methionine poultry feed according to claim 5, characterized in that The feed comprises the following components by mass percentage: 0.15%-0.30% of betaine hydrochloride, 0.20%-0.40% of pH buffer, 50.0%-52.0% of corn, 5.0%-7.0% of flour, 25.0%-27.0% of soybean meal, 2.0%-4.0% of corn gluten meal, 1.0%-3.0% of cottonseed meal, 1.0%-3.0% of sunflower kernel meal, 6.0%-8.0% of soybean oil, 0.4%-0.6% of stone powder, 1.0%-1.5% of calcium hydrogen phosphate, 0.2%-0.5% of sodium chloride, 0.6%-0.9% of L-lysine and 0.8%-1.2% of premix.

7. The low methionine poultry feed according to claim 5 or 6, characterized in that The premix comprises the following components: Vitamin A, Vitamin E, Vitamin D3, Vitamin K3, Thiamine, Riboflavin, Pyridoxine, Vitamin B 12 , calcium pantothenate, niacin, folic acid, D-biotin, choline chloride, copper sulfate pentahydrate, iron sulfate heptahydrate, zinc sulfate, manganese sulfate monohydrate, sodium selenite, and potassium iodide.

8. The low methionine poultry feed according to claim 7, characterized in that The premix includes the following components: vitamin A 9000-11000 IU / kg, vitamin E 30-40 mg / kg, vitamin D3 3500-4000 IU / kg, vitamin K3 2-6 mg / kg, thiamine 4-8 mg / kg, riboflavin 1-3 mg / kg, pyridoxine 2-6 mg / kg, vitamin B 12 0.01-0.05mg / kg, calcium pantothenate 15-25mg / kg, niacin 80-90mg / kg, folic acid 1-4mg / kg, D-biotin 0.1-0.3mg / kg, choline chloride 1600-2000mg / kg, copper sulfate pentahydrate 1-5mg / kg, iron sulfate heptahydrate 70-90mg / kg, zinc sulfate 40-60mg / kg, manganese sulfate monohydrate 90-110mg / kg, sodium selenite 0.05-0.2mg / kg and potassium iodide 0.1-0.5mg / kg.

9. Use of the low methionine poultry feed according to any one of claims 1 to 8 in broiler chicken farming.

10. The use according to claim 9, characterized in that The broiler chickens are 22-42 days old broiler chickens.

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