Product for improving spermatogenic function of testis of boar under heat stress and application thereof

Abstract

The invention relates to the technical field of animal breeding, in particular to a product for improving the spermatogenic function of testis of a boar under heat stress and application of the product. According to the invention, a Rongchang boar under heat stress is taken as a model, the NAD + level in dynamic testis can be effectively improved by supplementing 30mg / kg BW / d of nicotinamide nucleoside, and the decrease of the NAD + level in the testis caused by heat stress is improved. In addition, the invention also finds that by supplementing 30mg / kg BW / d of nicotinamide riboside, the semen quality can be improved, the spermatogenesis defect can be reduced, and oxidative stress and inflammatory response caused by heat stress can be alleviated. Therefore, supplement of the NAD + precursor plays an important role in relieving testis injury of the boar under heat stress and improving semen quality.

Description

Technical Field

[0001] The invention relates to the technical field of animal breeding, in particular to a product for improving the spermatogenesis function of boar testicles under heat stress and application thereof. Background Art

[0002] In recent years, with the intensive and large-scale development of pig farming in my country, artificial insemination technology has been increasingly popularized. Excellent semen quality is one of the important links. The reproductive performance of sows, such as conception rate, litter rate and litter weight of piglets, will be affected by the quality of boar semen. Therefore, ensuring excellent semen quality is an important prerequisite for ensuring the economic benefits of pig farming.

[0003] The semen quality of boars is mainly affected by factors such as breed, age, season, feeding management and semen collection frequency. With the rise in global temperatures, extreme high temperature weather occurs frequently in various places, and seasonal infertility of boars has caused huge losses to the breeding industry. In order to ensure the normal occurrence of sperm, the testicular temperature is usually 2-8℃ lower than the core temperature. In the long-term high temperature and high humidity in summer, the testicular temperature of boars will rise, which will seriously affect the reproductive performance of boars. It can be manifested as: decreased libido, decreased semen quality, decreased sperm motility, increased sperm deformity rate and damaged testicular morphology. Heat stress impairs semen quality, mainly due to increased inflammation, oxidative imbalance and cell apoptosis. Therefore, in high temperature and high humidity climates, especially in summer, full attention should be paid to the impact of heat stress on the semen quality of boars and timely and active countermeasures should be taken.

[0004] Nicotinamide adenine dinucleotide (NAD + ) participates in various cellular reactions and is an important cofactor in many biological redox processes. It plays a key role in cell homeostasis and is both a component of the mitochondrial electron transport chain and a co-substrate for many enzymatic processes. + Levels decrease in various pathological and stressful conditions, including aging, obesity, inflammation, cardiovascular, and neurodegenerative diseases.

[0005] Spermatogenesis is a complex process that includes three distinct phases: a proliferation phase (mitosis of spermatogonia), a first meiotic phase, a second meiotic phase (two rounds of meiosis produce haploid spermatids), and differentiation (spermatogenesis), during which spermatids mature into motile sperm. The spermatogenesis process requires a high mitochondrial density and is accompanied by extensive heat production. Therefore, the testes are very susceptible to damage caused by heat stress. Heat stress can damage the testes by disrupting blood flow, causing apoptosis of intestinal epithelial cells, and increasing intestinal permeability, which can lead to systemic inflammation. In addition, heat stress induces oxidative stress and mitochondrial dysfunction, both of which accelerate the depletion of cellular NAD. + However, it is still unclear whether NAD+ Whether the addition of the precursor can alleviate the oxidative damage caused by heat stress. Summary of the Invention

[0006] The object of the present invention is to provide a product and its application for improving the spermatogenic function of boar testes under heat stress to solve the problems existing in the above-mentioned prior art.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides an application of nicotinamide adenine dinucleotide precursor in improving the spermatogenic function of boar testes under heat stress, and the nicotinamide adenine dinucleotide precursor includes nicotinamide riboside.

[0009] The present invention provides an application of nicotinamide adenine dinucleotide precursor in the preparation of a product for improving the spermatogenic function of boar testes under heat stress, and the nicotinamide adenine dinucleotide precursor includes nicotinamide riboside.

[0010] Preferably, the product includes a drug, a feed additive or feed.

[0011] Preferably, the product improves the spermatogenic function of boar testes under heat stress by improving the semen quality of boars, improving NAD + metabolism, alleviating oxidative stress in boar testes and alleviating inflammatory reactions in boar testes.

[0012] More preferably, the improvement of boar semen quality includes increasing the sperm density of boars, reducing the sperm head malformation rate, reducing the sperm tail malformation rate, reducing the proportion of inactive sperm, increasing sperm motility, increasing the straight-line motility rate of sperm, reducing the sperm DNA fragmentation rate, increasing the diameter of seminal vesicles, increasing the epithelial area of seminal vesicles and reducing the vacuolization in seminal vesicles.

[0013] More preferably, the alleviation of oxidative stress in boar testes includes increasing the contents of T-AOC, SOD and CAT and reducing the content of MDA.

[0014] More preferably, the alleviation of inflammatory reactions in boar testes includes reducing the levels of IL-1β and TGF-β in the testes.

[0015] The present invention provides a drug for improving the spermatogenic function of boar testes under heat stress, the drug includes nicotinamide adenine dinucleotide precursor; the nicotinamide adenine dinucleotide precursor includes nicotinamide riboside; the dosage form of the drug is solid or liquid.

[0016] The present invention provides a feed additive for improving the spermatogenic function of boar testes under heat stress. The feed additive comprises a nicotinamide adenine dinucleotide precursor; the nicotinamide adenine dinucleotide precursor comprises nicotinamide riboside; and the dosage form of the feed additive is solid or liquid.

[0017] The present invention provides a feed for improving the spermatogenic function of boar testes under heat stress. The feed comprises a basal diet and the above-mentioned feed additive.

[0018] The present invention provides the use of the above-mentioned drug, the above-mentioned feed additive or the above-mentioned feed in improving the spermatogenic function of boar testes under heat stress.

[0019] The present invention provides a method for raising boars, which comprises the step of feeding boars with the above-mentioned feed additive or the above-mentioned feed.

[0020] Preferably, the number of times of feeding is 2 times.

[0021] Preferably, based on the mass of nicotinamide riboside, the feeding amount of the feed additive or the feed is 30 mg / kg BW / d.

[0022] The present invention discloses the following technical effects:

[0023] 1) Using Rongchang boars under heat stress as a model, the present invention discovers through non-targeted metabolomics technology that NAD + deficiency is a marker of testicular injury under heat stress, and heat stress accelerates the degradation of NAD + by increasing the expression of key NAD + consuming enzyme genes CD38, PARP1 and SIRT4. The present invention pioneers the exploration of the mechanism of testicular injury caused by heat stress from the perspective of NAD + metabolism, opening up a new direction for alleviating the decline of boar reproductive performance caused by heat stress.

[0024] 2) It improves the cultivation quality of boars: supplementing NAD + precursors can improve testicular injury caused by heat stress and improve the semen quality of boars. The implementation effects are reflected in the following aspects: First, after supplementing NAD + precursors, the semen density and sperm motility of boars under heat stress are significantly increased, the sperm malformation rate and DNA fragmentation rate are significantly reduced, and the spermogenesis defects caused by heat stress are improved; Second, after supplementing NAD + precursors, the expression levels of NAD + synthesis genes NMNAT3 and NAMPT in testicular tissues are significantly increased, the antioxidant and anti-inflammatory abilities of testicular tissues are improved, and further the testicular injury caused by heat stress is alleviated.

[0025] In summary, the present invention uses Rongchang boars under heat stress as a model and finds that supplementing 30 mg / kg BW / d of nicotinamide riboside can effectively increase the NAD + level in the testis and improve the decrease in testicular NAD + level caused by heat stress. In addition, the present invention also finds that supplementing 30 mg / kg BW / d of nicotinamide riboside can also improve semen quality, reduce spermatogenesis defects, and alleviate oxidative stress and inflammatory responses caused by heat stress. Therefore, supplementing NAD + precursors plays an important role in alleviating testicular damage in boars under heat stress and improving semen quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 It is a diagram showing the effect of NR on semen quality under heat stress; among them, A is the experimental flow chart, and HS-NR is the HS-NR1 group, HS-NR2 group, and HS-NR3 group; B is the chart of the results of the temperature-humidity index survey; C is the statistical chart of rectal temperature; D is the statistical chart of scrotal temperature; E is the statistical chart of testicular weight; F is the statistical chart of epididymal weight; G is the statistical chart of sperm density; H is the statistical chart of sperm head malformation rate; I is the statistical chart of sperm tail malformation rate; J is the statistical chart of sperm motility; K is the statistical chart of sperm straight-line motility rate; L is the statistical chart of the inactive proportion; M is the statistical chart of DNA fragmentation rate;

[0028] Figure 2 It is a diagram showing the effect of NR on the tissue morphology of semen under heat stress; among them, A is the statistical chart of the diameter of seminal vesicle tubules; B is the statistical chart of the area of seminal vesicle epithelium; C is the statistical chart of vacuolization in seminal vesicle tubules; D is the statistical chart of the relative expression level of VASA; E is the statistical chart of the relative expression level of STRA8; F is the statistical chart of the relative expression level of PRM2;

[0029] Figure 3 It is the non-targeted metabolomics analysis of testicular tissue; among them, A is the volcano plot of metabolic differential substances between HS and CON; B is the KEGG pathway enrichment map of metabolic differential substances between HS and CON; C is the volcano plot of metabolic differential substances between HS and HS-NR2; D is the KEGG pathway enrichment map of metabolic differential substances between HS and HS-NR2; E is the sunburst plot of supplementing NR (HS vs. HS-NR2) under HS (HS vs. CON); F is the KEGG pathway enrichment map of the metabolic differential substances in the sunburst plot;

[0030] Figure 4 is NAD + Statistical chart of anabolic and catabolic metabolites;

[0031] Figure 5 For non-targeted metabolomics analysis of testicular tissue; wherein, A is NAD + Statistical chart of synthetic genes; B is NAD + Statistical chart of catabolic genes;

[0032] Figure 6 Graph showing the effects of oxidative stress and inflammatory response in NR testes under heat stress; wherein, A is the statistical chart of T-AOC; B is the statistical chart of SOD; C is the statistical chart of CAT; D is the statistical chart of MDA; E is the statistical chart of IL-1β level; F is the statistical chart of GF-β level. Detailed implementation mode

[0033] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation on the present invention, but rather as a more detailed description of certain aspects, features, and implementation schemes of the present invention.

[0034] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0035] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0036] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation modes of the present invention specification, which are obvious to those skilled in the art. Other implementation modes obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0037] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0038] Unless otherwise specified, the components and instruments used in this invention are all routinely purchased by those skilled in the art; the methods used are methods well-known to those skilled in the art.

[0039] Example 1

[0040] 1. Feeding and grouping

[0041] In this experiment, 40 Rongchang boars weighing 11 - 13 kg were selected and randomly divided into 5 treatment groups according to body weight, namely the room temperature blank control group (CON), the heat stress (HS) group, and the groups supplemented with nicotinamide riboside (NR), a NAD + precursor, with NR addition amounts of 15, 30, and 60 mg / kg BW / d respectively, denoted as HS-NR1 group, HS-NR2 group, and HS-NR3 group in sequence. Among them, the feeding method of nicotinamide riboside + precursor: The basal diet was formulated according to the nutritional guidelines in "Nutritional Standards for Chinese Native Pig Breeds", with a metabolic energy of 3.15 Mcal / kg and a crude protein of 15%. The nicotinamide riboside + precursor was fed in two portions by mixing with a small amount of feed at 15, 30, and 60 mg / kg BW after the first and last meals of the day.

[0042] Each treatment group had 8 replicates, with 1 pig in each replicate. The experiment lasted for 6 weeks. In the first 4 weeks, the 5 treatment groups were kept under the same conditions: free access to food and water, the environmental temperature was maintained at 26 ± 1°C (thermoneutral condition), and the environmental humidity was maintained at 80% - 90%. The monitoring method of temperature and humidity in the pen: At the middle position of the pen, a JianDa Renke temperature and humidity recorder was placed at a height of 60 cm from the ground, and the temperature and humidity in the pen were automatically recorded every half hour.

[0043] In the 5th week, the HS group, HS-NR1 group, HS-NR2 group, and HS-NR3 group started to increase the temperature at 8 am, with a 2°C increase every 2 h until the temperature reached 35°C, and then the temperature was maintained at 35 ± 1°C (heat stress condition), and the humidity was maintained at 60% - 70%. During this period, the pigs had free access to food and water until the end of the 6th week of the experiment.

[0044] 2. Detection method

[0045] Rectal temperature detection: When the pigs were resting quietly, a handheld electronic thermometer was used to insert the thermometer probe 3 - 4 cm into the anus of the boar, and wait for 30 s until the thermometer beeped and showed the temperature. Each pig was detected 3 times, and the average value was recorded.

[0046] Scrotal temperature detection: When the pigs are eating quietly and standing on all four feet, lift the tail with your hand and use a handheld thermal imaging thermometer to record the scrotal temperature. Each pig is detected 3 times, and the average value is recorded.

[0047] Semen quality detection: After the pigs are anesthetized, dissect the testes and epididymides. Make a small cut of 1 - 2 cm on the head and tail of the epididymis, and flush out the semen in the epididymis with 10 mL of normal saline. Place it at 37 °C and let it stand for 15 - 30 min to wait for natural liquefaction. After liquefaction, gently mix it, and use computer-assisted semen analysis to automatically analyze sperm concentration, motility, and movement parameters.

[0048] Detection of sperm DNA fragmentation rate: The liquefied semen is washed with PBS and the sperm concentration is adjusted to 1×10 6 mL, fixed with 4% paraformaldehyde, permeabilized with 0.1% TritonX - 100, add TdT enzyme and fluorescently labeled dUTP, incubate at 37 °C for 1 h, wash with PBS, DAPI nuclear staining, and use a flow cytometer with 488 nm laser to excite FITC fluorescence to detect the proportion of TUNEL-positive sperm.

[0049] Detection of sperm deformity rate: The liquefied semen is stained with Giemsa stain. The stained semen sample is smeared on a slide and observed under a microscope after drying. According to the World Health Organization standards, evaluate the morphology of the sperm head, neck, and tail.

[0050] Testis non-targeted metabolomics detection: After the pigs are anesthetized, dissect the testes and epididymides. Quickly put the testis tissue into liquid nitrogen for freezing, grind it into powder, add the extraction solvent (methanol / water) to extract metabolites, use a vacuum centrifugal concentrator to concentrate the supernatant of the extraction solvent, use liquid chromatography - mass spectrometry to detect metabolites, and use Progenesis QI for peak extraction, alignment, and normalization of the original data processing, and use tools such as KEGG and MetaboAnalyst to analyze the metabolic pathways involved in metabolites.

[0051] Testis tissue morphology detection: Cut a small square of 2 cm×2 cm×2 cm from the testis tissue, fix it with 4% paraformaldehyde, dehydrate it, and embed it in paraffin. The paraffin-embedded testis is sectioned into 5 μm sections, mounted on glass slides, and stained with hematoxylin and eosin using a standard protocol. Use NDP.view software to measure the diameter of the seminiferous tubules, the area of the seminiferous tubule epithelium, and the vacuolation area.

[0052] Detection of key genes such as testicular spermatogenesis: Extract total RNA from the testis tissue using TRIzol reagent and purify it using an RNA microcolumn. Synthesize cDNA from 1 μg of RNA. RT-PCR is carried out using SYBR Green dye in a 10 μL reaction volume.

[0053] ELISA assay: Equal amounts of testicular tissues were homogenized with an equal volume of PBS in an ice - water bath. At 4°C, the samples were centrifuged at 12,000 g for 15 min, and the supernatant was collected to detect antioxidant enzymes and inflammatory factors according to the instructions of Solarbio.

[0054] 3. Experimental results

[0055] (1). NR improves semen quality under heat stress

[0056] To evaluate the effect of the NAD + precursor nicotinamide riboside on semen quality under HS conditions, control diets or diets supplemented with the NAD + precursor nicotinamide riboside (NR) were provided to Rongchang boars under thermoneutral conditions (4 weeks) and heat stress conditions (2 weeks) ( Figure 1 A in). The temperature - humidity index (THI) of the HS group was significantly higher than that of the control group ( Figure 1 B in) (P < 0.05). HS significantly increased the core temperature (rectal temperature) of the boars, but had no significant effect on scrotal temperature ( Figure 1 C and D in) (P > 0.05). Supplementing with NR (15, 30, 60 mg / kg) did not significantly change the core temperature and scrotal temperature ( Figure 1 C and D in) (P > 0.05). In addition, there were no statistical differences in testicular weight and epididymal weight among the five groups ( Figure 1 E and F in) (P > 0.05).

[0057] To determine whether supplementing with NR could alleviate semen quality defects caused by heat stress, sperm density was first measured. Notably, it was found that the decrease in sperm density caused by HS could be restored by supplementing with NR (15, 30 mg / kg) ( Figure 1 G in) (P < 0.05), but there was no significant difference in sperm density between the group supplemented with 60 mg / kg of NR and the HS group ( Figure 1 G in) (P > 0.05). Compared with the control group, HS also increased the proportions of sperm with head and tail deformities, as well as the proportion of immotile sperm, but supplementing with NR (30, 60 mg / kg) alleviated these effects ( Figure 1 H, I and L in) (P < 0.05). In addition, HS decreased sperm motility and linear motility, but the supplementation of NR (15, 30, 60 mg / kg) reversed these damages ( Figure 1 J and K in) (P < 0.05), and the straight - line motility rate of sperm in the group supplemented with NR (30 mg / kg) recovered to the same level as that of the control group ( Figure 1K)(P < 0.05) in it. In addition, HS increased the DNA fragmentation rate in semen, while the addition of NR (30, 60 mg / kg) significantly decreased the DNA fragmentation rate ( Figure 1 M)(P < 0.05) in it. In summary, these results highlight the supplementation of NAD + precursor (30 mg / kg) plays a protective role in preserving semen quality.

[0058] (2), NR can attenuate spermatogenesis defects caused by heat stress

[0059] Next, H&E staining was used to evaluate the changes in testicular tissue morphology. HS led to a decrease in the diameter of seminiferous tubules and the area of seminiferous epithelium, and at the same time increased the vacuolization in seminiferous tubules ( Figure 2 A-C) in it (P < 0.05). However, the supplementation of NR (30 mg / kg) effectively reversed these histological defects caused by HS ( Figure 2 A-C) in it (P < 0.05).

[0060] Further studies were conducted to determine whether the effect of NR on seminiferous tubules is specific to certain germ cell types. Consistent with previous studies, HS impaired spermatogenesis, while NR supplementation increased the expression of germ cell (VASA), spermatogonial (STRA8), and spermatid (PRM2) marker genes ( Figure 2 D-F) in it, but the supplementation of NR (30 mg / kg) had the most significant effect (P < 0.05). These results indicate that NR can alleviate HS-induced spermatogenesis defects.

[0061] (3), Heat stress impairs testicular NAD + metabolism and is rescued by the supplementation of NR

[0062] From the previous experimental results, it can be concluded that the experimental effect is the best when 30 m / kg NR is supplemented. Therefore, untargeted metabolomics analysis of testicular tissues in three groups of CON, HS, and supplemented with 30 m / kg NR (HS-NR2) was performed to understand how overall changes in cellular metabolism contribute to the effects of HS and NR in the testis. A total of 2106 metabolites were identified in testicular tissues. Compared with the control group, 311 metabolites in the HS group changed significantly, among which 27 metabolites increased and 284 metabolites decreased ( Figure 3 A) in it (P < 0.05). Pathway enrichment analysis performed using a metabolomics analyzer (v.5.0) showed that pyruvate metabolism, amino acid metabolism, and the citric acid cycle all changed significantly ( Figure 3in B). Compared with the HS group, NR supplementation significantly regulated 203 metabolites (63 increased and 140 decreased), which were significantly enriched in lipid metabolism, nicotinic acid and nicotinamide (NAM) metabolism, and mitochondrial electron transport chain ( Figure 3 in C and D) (P < 0.05).

[0063] The effect of NR supplementation under HS (HS vs. CON) was further analyzed (HS vs. HS-NR2). Among the 27 metabolites upregulated in the HS group, 14 did not change significantly in the NR supplementation group ( Figure 3 in E) (P > 0.05). Similarly, among the 285 metabolites downregulated in the HS group, 222 showed no significant difference (P > 0.05), and 1 of them was significantly upregulated after adding NR ( Figure 3 in E) (P < 0.05). These differentially expressed metabolites were mainly enriched in nucleotide sugar metabolism, nicotinic acid and nicotinamide metabolism, and mitochondrial electron transport chain ( Figure 3 in F).

[0064] Focusing on the enrichment of NR related to nicotinic acid and NAM metabolism, it was observed that NR, as a NAD + precursor, directly affected this pathway ( Figure 3 in F). Compared with the control group, the NAD + level in the HS group decreased, but NR supplementation effectively alleviated this decrease ( Figure 4 )(P < 0.05). Although the metabolites involved in the NAD + synthesis pathway (de novo synthesis pathway and Preiss-Handler pathway) did not show significant changes between the HS and HS-NR groups (P > 0.05), the metabolites NAM, nicotinamide mononucleotide (NMN), and NR in the salvage synthesis pathway were significantly lower in the NAD + level of the HS group than in the HS-NR group ( Figure 4 )(P < 0.05). Notably, the downstream metabolites 1-methylnicotinamide and pyruvate in the HS group were significantly decreased, but NR supplementation restored the 1-methylnicotinamide level ( Figure 4 )(P < 0.05). In summary, untargeted metabolomics analysis showed that HS disrupted testicular NAD + metabolism, and this damage could be effectively rescued by NR supplementation.

[0065] To detect the effect of HS on NAD + synthesis, the expression levels of key genes related to NAD synthesis were measured. It was found that HS did not impair NAD + synthesis. However, treatment with NR (30, 60 mg / kg) increased the expression levels of NMNAT3 and NAMPT ( Figure 5A) (P < 0.05) in. Interestingly, HS passes through NAD + The expressions of the key consuming enzyme genes CD38, PARP1, and SIRT4 of NAD were significantly increased, significantly increasing the degradation of NAD + ( Figure 5 B) (P < 0.05) in. The results showed that HS increased the degradation of NAD + , while NR (30 mg / kg) enhanced its synthesis.

[0066] (4), Supplementing NR can alleviate oxidative stress and inflammatory responses in the testis under heat stress

[0067] Oxidative stress and inflammation are key factors in sperm damage during HS. To determine whether supplementing NR can relieve oxidative damage caused by HS, the levels of antioxidant enzymes were evaluated. Compared with CON, HS significantly decreased the antioxidant indices in the testis, including total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and catalase (CAT), while significantly increasing malondialdehyde (MDA) Figure 6 A-D) in (P < 0.05). Notably, supplementing NR (30 mg / kg) effectively reversed these trends Figure 6 A-D) in (P < 0.05). To evaluate the effect of supplementing NR on testicular inflammation, inflammation-related markers were measured. Heat stress increased the levels of testicular IL-1β and TGF-β Figure 6 E and F) in (P < 0.05). However, supplementing NR (30 mg / kg) significantly attenuated these increases Figure 6 A-D) in (P < 0.05). These results indicate that supplementing NR (30 mg / kg) can relieve oxidative stress and inflammatory responses induced by HS, highlighting its potential protective effect on heat stress-related testicular damage.

[0068] In summary, NAD + deficiency is a marker of testicular damage under HS conditions and demonstrates that supplementing 30 mg / kg NR can effectively relieve spermatogenic defects. These findings highlight the potential of NAD + precursors as a viable nutritional strategy to mitigate the adverse effects of HS on male reproductive health.

[0069] The embodiments described above are only for describing the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. Application of nicotinamide adenine dinucleotide precursor in improving testicular spermatogenesis in boars under heat stress, characterized in that: The nicotinamide adenine dinucleotide precursor includes nicotinamide riboside.

2. The use of a nicotinamide adenine dinucleotide precursor in the preparation of a product for improving the testicular spermatogenesis function of boars under heat stress, characterized in that: The nicotinamide adenine dinucleotide precursor includes nicotinamide riboside.

3. The use according to claim 2, characterized in that: The products include medicines, feed additives or feeds.

4. The use according to claim 2, characterized in that: The product improves the quality of boar semen and improves boar testicular NAD + Metabolism, reduce oxidative stress in boar testicles and reduce inflammatory response in boar testicles, thereby improving the spermatogenesis function of boar testicles under heat stress.

5. A drug for improving the testicular spermatogenesis function of boars under heat stress, characterized in that: The drug includes a nicotinamide adenine dinucleotide precursor; the nicotinamide adenine dinucleotide precursor includes nicotinamide riboside; and the drug is in the form of a solid or liquid.

6. A feed additive for improving the testicular spermatogenesis function of boars under heat stress, characterized in that: The feed additive comprises a nicotinamide adenine dinucleotide precursor; the nicotinamide adenine dinucleotide precursor comprises nicotinamide riboside; and the feed additive is in the form of a solid or liquid.

7. A feed for improving the spermatogenesis function of boar testicles under heat stress, characterized in that: The feed comprises a basic diet and the feed additive according to claim 6.

8. Use of the medicine according to claim 5, the feed additive according to claim 6 or the feed according to claim 7 in improving the testicular spermatogenesis function of boars under heat stress.

9. A boar breeding method, characterized in that: The method comprises the step of feeding boars with the feed additive according to claim 6 or the feed according to claim 7.

10. The boar breeding method according to claim 9, characterized in that: The number of feedings is 2 times; The feeding amount of the feed additive or the feed is 30 mg / kg BW / d based on the mass of the nicotinamide riboside.

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