Patterns of alteration in boar semen quality from 9 to 37 months old and improvement by protocatechuic acid

Background Comprehending the patterns of alteration in boar semen quality and identifying effective nutritional interventions are crucial for enhancing the productivity of commercial pig systems.This study aimed to examine the alteration in semen quality in boars,and assess the impact of protocatechuic acid(PCA)on semen quality during the phase of declining semen quality.Methods In Exp.1,a total of 38 Pig Improvement Company(PIC)boars were selected and their semen quality data were recorded from the age of 9 to 37 months.In Exp.2,18 PIC boars(28 months old)were randomly assigned into three groups(n=6)and fed a basal diet,a basal diet containing 500 or 1,000 mg/kg PCA,respectively.The experiment lasted for 12 weeks.Results The semen volume,concentration,and total number of spermatozoa in boars exhibited an increase from 9 to 19 months old and showed a significant linear decreased trend in 28,24,and 22 months old.Sperm motility displayed an upward trajectory,reaching its peak at 20 months of age,and showed a significant linear decreased trend at 20 months old.Dietary supplementation of PCA demonstrated an effect to mitigate the decrease in semen volume,concentration of spermatozoa,total number of spermatozoa(P>0.05),and significantly increased the sperm motility(P<0.05).Moreover,supplementation of 1,000 mg/kg PCA significantly increased the sperm viability(P<0.05).Analysis on cellular signaling pathways revealed that PCA restored serum testosterone levels and alleviated oxidative damage by upregulating the expression of HO-1,SOD2,and NQO1 in testicular stromal cells.Notably,PCA can enhance phosphorylation by selectively binding to AMP-activated protein kinase(AMPK)protein,thereby improving sperm mitochondrial function and augmenting sperm motility via PGC-1/Nrf1.Conclusions These data elucidated the pattern of semen quality variation in boars within the age range of 9 to 37 months old,and PCA has the potential to be a natural antioxidant to enhance sperm quality through modulation of the AMPK/PGC-1/Nrf1 signaling pathway.

Source and level of dietary iron influence semen quality by affecting inflammation, oxidative stress and iron utilization levels in boars

Background Boars fed a mixed form of inorganic and organic iron in excess of the NRC recommended levels still develop anemia,which suggested that the current level and form of iron supplementation in boar diets may be inappropriate.Therefore,56 healthy Topeka E line boars aged 15–21 months were randomly divided into 5 groups:basal diet supplemented with 96 mg/kg ferrous sulfate(FeSO_(4))and 54 mg/kg glycine chelated iron(Gly-Fe,control);80 mg/kg or 115 mg/kg Gly-Fe;80 mg/kg or 115 mg/kg methionine hydroxyl analogue chelated iron(MHA-Fe,from CalimetFe)for 16 weeks.The effects of dietary iron supplementation with different sources and levels on semen quality in boars were investigated.Results 1)Serum Fe and hemoglobin concentrations were not affected by reduced dietary iron levels in the 80 mg/kg or 115 mg/kg Gly-Fe and MHA-Fe groups compared with the control group(P>0.05).2)Serum interleukin-6(IL-6)and sperm malondialdehyde(MDA)levels in the 80 mg/kg or 115 mg/kg MHA-Fe groups were lower than those in the control group(P<0.05),and higher serum superoxide dismutase levels and lower MDA levels in the 115 mg/kg MHA-Fe group(P<0.05).3)Boars in the 80 mg/kg or 115 mg/kg Gly-Fe and MHA-Fe groups had lower serum hepcidin(P<0.01),ferritin(P<0.05),and transferrin receptor(P<0.01)concentrations,and boars in the 115 mg/kg MHA-Fe group had higher seminal plasma Fe concentrations compared with the control group.4)Boars in the 80 mg/kg and 115 mg/kg MHA-Fe groups had lower abnormal sperm rate and in situ oscillating sperm ratio compared to the control group at weeks 12 and/or 16 of the trial.However,the effect of Gly-Fe on improving semen quality in boars was not evident.5)Serum IL-6 level was positively correlated with hepcidin concentration(P<0.05),which in turn was significantly positively correlated with abnormal sperm rate(P<0.05).Furthermore,significant correlations were also found between indicators of iron status and oxidative stress and semen quality parameters.Conclusions Dietary supplementation with 80 mg/kg or 115 mg/kg MHA-Fe did not induce iron deficiency,but rather reduced serum inflammatory levels and hepcidin concentration,alleviated oxidative stress,increased body iron utilization,and improved semen quality in adult boars.

Pig Reproductive and Respiratory Syndrome Virus (PRRSV) Does Not Attach to Boar Sperm;It Affects Only the Velocity Pattern and the Mobility Pattern

The purpose of the study was to evaluate the sperm viability of semen infected with PRRSV viral particles, observing the effect of the Virus on the motility of boar sperm. The work was carried out at the FMVZ-BUAP Genetics and Reproduction Laboratory. 5 stallions were used. Each sample contained 1 × 106 sperm, the PRRS virus strain was ATCC-VR-2332 (0, 102, 104 and 106 copies of RNA/mL in triplicate), it was observed daily at the CASA;Hamilton Thorne®. Cells with MT (P < 0.05) on days 1, 3, 5, 7 and 10 of evaluation with 201 ± 7.3, 167 ± 10.1, 165 ± 14.6, 134 ± 8.2 and 120 ± 8.8, respectively. The % MP between control and virus concentrations (P ≥ 0.05). The LCV on day 1 and 7 PI at 10X2 and 10X6 (P < 0.05) vs control. In the Correlation Matrix, where it is observed that there is a correlation between VSL and VAP, VSL and VCL, VCL and ALH, VAP with ALH. There is a correlation of VSL and ALH, STR and ALH. In this study there were (P ≤ 0.01) in the VCL, in the concentrations (102) 162.81 ± 10.65 and (106) 177.12 ± 5.77 vs 193.04 ± 4.62 of control. This indicates that altering these parameters would be related to fertility and the PRRS virus affects the LCV. Regarding the VSL, it was observed that the sperm infected with viruses 102, 104 and 106 of 48.00 ± 3.38, 49.88 ± 1.83 and 50.55 ± 2.24 Vs. 56.66 ± 1.68 of control respectively, the control would have greater possibilities of fertilizing the oocyte. In this study, it was found (P ≤ 0.01) in the VAP with 102 of 77.26 ± 5.16, 104 with 83.35 ± 2.41 and 106 with 81.29 ± 3.14 vs the control with 90.56 ± 2.07. Regarding the ALH there is (P < 0.05) a 104 with 8.70 ± .26 and 106 with 9.64 ± 0.23 vs control 8.50 ± 0.27. The presence of different concentrations of PRRSV in boar semen induces changes in different types of sperm motility. Infection of ejaculates with the PRRS virus affects sperm motility on days 1, 3, 5, 7, and 10 post-infections.

Bacteriospermia among smallholder artificial insemination boars in the Philippines and potential associated factors

Objective:To determine the prevalence of bacteriospermia,the bacterial load,and the potential factors associated with bacterial contamination in boar semen collected by local smallholder artificial insemination operators.Methods:Fifteen individual raw semen samples were collected from locally available artificial insemination boars owned by different smallholder boar operators within the 5th district of Leyte,Philippines and were subjected to standard bacteriological culture and identification,including a survey of potentially associated factors.Prevalence and bacterial count were determined accordingly,while boar characteristics and collection practices were clustered following agglomerative hierarchical clustering technique.Results:One hundred percent contamination with a bacterial count of(2.01±0.38)×10^(3) CFU/mL was observed.At least 73.33%of the samples were positive for Bacillus spp.,while other identified isolates included Enterobacter spp.,Staphylococcus spp.,E.coli,Pseudomonas spp.,Citrobacter spp.,and Klebsiella spp.Conclusions:Despite the high prevalence of bacteriospermia,the bacterial count is low.Nevertheless,on-farm practices on boar health and management,semen collection,and sanitation as well as the enhancement of basic protocols to control contamination should be conscientiously considered in smallholder artificial insemination operation.

Investigation on the Harm of Wild Boar in Mingtong Town, Chengkou, Chongqing

Through the investigation and analysis of the wild boars in Mingtong Town, Chengkou, Chongqing, it was concluded that the area had long been seri- ously affected by wild boars and some of the human activities were potentially threatened, and the potential threat areas were identified. Corresponding suggestions were proposed to guide the prevention and control work, so as to protect the habi- tat and reproduction of wildlife and ensure the normal production and life of the masses.

Effects of DHA-enriched hen egg yolk and L-cysteine supplementation on quality of cryopreserved boar semen

The objective of the present study was to determine the effects of docosahexaenoic acid （DHA）-enriched hen egg yolks and L-cysteine supplementation on the qualities of the cryopreserved boar semen. A total of 15 ejaculates from 5 Pietrain boars were divided into 4 groups according to the compositions of the freezing extenders used, that is, normal hen egg yolk （group Ⅰ）, DHA-enriched hen egg yolk （group Ⅱ）, normal hen egg yolk with 5 mmol L^-1 of cysteine supplementation （group Ⅲ） and DHA-enriched hen egg yolk with 5 mmol L1 of cysteine supplementation （group Ⅳ）. The semen was cryopreserved using controlled rate freezer and was thawed at 50℃ for 12 s. Progressive motility, sperm viability, acrosome integrity and functional integrity of sperm plasma membrane of the post-thawed semen were evaluated. The supplementation of L-cysteine in the freezing extender alone （group Ⅲ） improved progressive motility （P 〈 0.05）, and the supplementation of L-cysteine in combination with DHA-enriched hen egg yolk （group Ⅳ） improved both progressive motility （P 〈 0.05） and acrosome integrity （P 〈 0.01）. The use of DHA-enriched hen egg yolk alone （group Ⅱ） did not enhance any of the post-thawed semen qualities （P 〉 0.05）. In conclusion, the supplementation of antioxidant L-cysteine alone or in combination with DHA-enriched hen egg yolk significantly improved the post-thawed semen qualities, especially progressive motility and acrosome integrity.

Supplemental effect of varying L-cysteine concentrations on the quality of cryopreserved boar semen

Cryopreservation is associated with the production of reactive oxygen species, which leads to lipid peroxidation of the sperm membrane and consequently a reduction in sperm motility and decreased fertility potential. The aim of this study was to determine the optimal concentration of L-cysteine needed for cryopreservation of boar semen. Twelve boars provided semen of proven motility and morphology for this study. The semen was divided into four portions in which the lactose-egg yolk （LEY） extender used to resuspend the centrifuged sperm pellet was supplemented with various concentrations of L-cysteine to reach 0 mmol L^-1 （group Ⅰ, control）, 5 mmol L^-1 （group Ⅱ）, 10 mmol L^-1 （group Ⅲ） and 15 mmol L^-1 （group Ⅳ）. Semen suspensions were loaded in straws （0.5 mL） and placed in a controlled-rate freezer. After cryopreservation, frozen semen samples were thawed and investigated for progressive motility, viability using SYBR-14/EthD-1 staining and acrosome integrity using FITC-PNA/EthD-1 staining. There was a significantly higher （P 〈 0.01） percentage of progressive motility, viability and acrosomal integrity in two L-cysteine-supplemented groups （group Ⅱ and group Ⅲ） compared with the control. There was a biphasic effect of L-cysteine, with the highest percentage of progressive motility, viability and acrosomal integrity in group Ⅲ. In conclusion, 5 or 10 mmol L^-1 was the optimum concentration of L-cysteine to be added to the LEY extender for improving the quality of frozen-thawed boar semen.

GSTM3, but not IZUMO1, is a cryotolerance marker of boar sperm

Background: Cryopreservation is currently the most efficient method for long-term preservation of mammalian gametes and is extensively used in swine artificial insemination(AI) centres. However, it is well-known that cryopreservation procedures induce changes in the water phase in both intra and extracellular compartments,which alter the content and localisation of several proteins and ends up curtailing the structural integrity of functional sperm(i.e., cryoinjuries). Alterations and deficiencies of sperm-oocyte binding proteins during gamete recognition are one of the causes of reproductive failure both in vitro and in vivo. In this sense, characterisation of cryopreservation effects upon oocyte-binding proteins of sperm, such as IZUMO1 and GSTM3, is essential when assessing the impact of this technique in swine reproduction.Results: Cryopreservation was found to induce changes in the localisation of IZUMO1 and GSTM3 in boar sperm.However, the relative content of both proteins was not altered after thawing. Furthermore, whereas IZUMO1 content was found not to be related to the cryotolerance of boar sperm, GSTM3 content was observed to be higher in poor(PFE) than in good(GFE) freezability ejaculates in both pre-frozen(1.00 INT·mm^2± 0.14 INT·mm^2 vs.0.72 INT·mm^2± 0.15 INT·mm^2;P < 0.05) and post-thawed(0.96 INT·mm^2± 0.20 INT·mm^2 vs. 70 INT·mm^2± 0.19 INT·mm^2;P < 0.05) samples. Moreover, GSTM3 levels were found to be higher in those spermatozoa that exhibited low mitochondrial activity, high reactive oxygen species(ROS) production, and high membrane lipid disorder postthaw(P < 0.05).Conclusions: The difference in GSTM3 content between GFE and PFE, together with this protein having been found to be related to poor sperm quality post-thaw, suggests that it could be used as a cryotolerance marker of boar spermatozoa. Furthermore, both IZUMO1 and GSTM3 relocate during cryopreservation, which could contribute to the reduced fertilising capacity of frozen-thawed boar sperm.

Conflict between wild boars(Sus scrofa) and farmers:distribution, impacts,and suggestions for management of wild boars in the Three Gorges Reservoir Area

Economic losses caused by wild boars(Sus scrofa)continue to increase in the Three Gorges Reservoir Area.We selected 206 farmers in Wuqiaohe Basin as survey respondents using random stratified sampling.The distribution and impacts of wild boars were examined using a questionnaire survey and spatial analysis.The results showed that:(1)The density of farmer settlements is low and most peasants’households are located on the forest edge.Due to large-scale labor migration,a high proportion of farmland(25.85%)has been abandoned and an even higher proportion of farmland(40.48%)has been returned to forest.(2)The probability of wild boar damage to peasant households was 67.96%.Yields of corn and sweet potato decreased by 24.87%and 28.24%,respectively,with a total economic loss of approximately 2,590,100 RMB/yr in the Wuqiaohe basin.Sixty-five percent of the affected cultivatedlands were located within approximately 150 m of the forest edges.(3)The wild boar damage coefficient was significantly and negatively correlated with the distance between the peasants’household and the forest edge,the density of the settlements,and the area of cultivated land.The wild boar damage coefficient shows a significant positive correlation with the area of farmland returned to forest.(4)The damage activity caused by wild boars began to occur7-8 years ago,and the destruction has been more frequently and seriously observed in the last 4-5 years.(5)We make suggestions for wild boar control and management measures including developing a compensation policy.The compensation standard is related to the land area returning from farmland to forests and the actual cultivated land area.

Analysis of the lifetime and culling reasons for AI boars

Background: The aim of the study was to analyze the lifetime and culling reasons for boars used in insemination centers(AI centers).Methods: The data collected from 355 culled boars from 1998 to 2013 included: age at start of semen collection,boar herd life, culling reason, daily gain and lean meat content, and number of ejaculates not meeting sales requirements after dilution. Culling reasons were divided into 7 groups: low semen value(LSV), low or lack of libido(LL), leg problems(LP), infectious diseases(ID), old age(OA), reduced demand for semen from the given boar(RD),and others(OT).Results: The most common culling reasons for boars were LSV(23.7%) and RD(22.5%). It was observed that the lowest daily gains were noted in boars culled due to OA. Boars culled due to OA and RD were maintained in production for the longest time(over 1000 d), for LSV and ID retention was about 700 d, and due to LL below 400 d. The survival probability was over 0.9 until 1.5 yr, and just over 0.2 until 4 yr. The highest relative frequency was observed in the 36 ^(th) and 42 ^(nd) mo of life(over 16%). Hazard risk analysis revealed a more than 10 times higher risk of culling in the case of LL, ID or OT, in comparison to OA.Conclusions: The results can be used as a direct point of reference for the identification of emerging problems in AI boar exploitation and the development of an appropriate culling policy in AI centers.

Effects of pituitary-specific overexpression of FSHα/β on reproductive traits in transgenic boars

Background： Follicle-stimulating hormone（FSH） is a gonadotropin synthesized and secreted by the pituitary gland.FSH stimulates follicle development and maturation in females. It also plays an important role in spermatogenesis in males, including humans and mice. However, the effects of FSH on male pigs are largely unknown. In this study,we generated transgenic pigs to investigate the effects of FSHα/β overexpression on reproductive traits in boars.Results： After five transgenic F0 founders were crossed with wide-type pigs, 193 F_1 animals were obtained. Of these,96 were confirmed as transgenic. FSHα and FSHβ m RNAs were detected only in pituitary tissue. Transgenic boars exhibited significantly higher levels of FSHα and FSHβ m RNA, serum FSH, and serum testosterone, compared to ful-sib non-transgenic boars. Significant increases in testis weight, vas deferens diameter, seminiferous tubule diameter,and the number of Leydig cel s were observed, suggesting that the exogenous FSHα/β affects reproductive traits. Final y,transgenic and non-transgenic boars had similar growth performance and biochemical profiles.Conclusions： Pituitary-specific overexpression of FSHα/β genes is likely to impact reproductive traits positively, as indicated by enhancements in serum testosterone level, testis weight, the development of vas deferens, seminiferous tubules, and Leydig cells in transgenic boars. A high level of serum FSH induces secretion of serum testosterone,possibly by boosting the number of Leydig cells, which presumably increases the libido and the frequency of sexual activity in transgenic boars. Our study provides a preliminary foundation for the genetic improvement of reproductive traits in male pigs.

In vitro performance and in vivo fertility of antibiotic-free preserved boar semen stored at 5℃

Background: Hypothermic preservation of boar semen is considered a potential method for omitting antibiotics from insemination doses, thereby contributing to the global antibiotic resistance defence strategy. The main challenges are chilling injury to spermatozoa and bacterial growth during semen storage leading to reduced fertility.Objectives: To examine chilling injury and the number and type of bacteria in boar semen stored at 5 ℃ in the absence of antibiotics, and to assess the applicability of hypothermic semen storage under field conditions.Material and methods: Boar ejaculates were extended with AndroStar~? Premium, stored at 17 ℃ with and at 5 ℃ without antibiotics and tested for functional sperm parameters by flow cytometry. Raw semen and extended samples were investigated bacteriologically. Fertility was evaluated after once-daily inseminations of 194 sows in a field study.Results: Lethal sperm damage assessed by motility and membrane integrity was low throughout storage in both experimental groups. Sublethal chilling effects based on the decrease of viable spermatozoa with low membrane fluidity were higher(P < 0.05) up until 72 h in sperm stored at 5 ℃ compared to 17 ℃ but did not differ after 144 h.After 72 h, incubation in capacitating medium for 60 min induced a similar decrease in viable sperm with high mitochondria membrane potential and low cytosolic calcium in both groups. In semen stored at 5 ℃, bacteria counts were below 103 CFU/mL and the bacteria spectrum was similar to that of raw semen. In 88% of 34 boars,cooled semen fulfilled the requirements for insemination. Fertility was high and did not differ(P > 0.05) between sow groups inseminated with semen stored antibiotic-free at 5 ℃ and semen stored at 17 ℃ with antibiotics.Conclusion: Despite subtle chilling effects and low bacterial numbers, antibiotic-free hypothermic storage of boar semen offers the possibility to reduce the use of antibiotics in pig insemination. However, strict sanitary guidelines must be maintained and further evidence of efficiency under field conditions is considered desirable.

Study on the Accuracy of Different CASA Systems in the Quality Detection of Fresh Boar Semen

[Objectives]This study was conducted to compare and analyze the accuracy of computer-aided sperm analysis(CASA)and manual method for detecting the quality of fresh boar semen at room temperature.[Methods]Statistical methods such as analysis of variance,ZB score and Z score were used to compare the accuracy of five different brands of CASA systems and manual method to detect the vitality and density of fresh boar semen at room temperature.[Results]After setting the parameters of five CASA systems the same as follows:VCL(curvilinear velocity),VSL(straight-line velocity)≥5μm/s,STR(straightness)=VSL(straight-line velocity)/VAP(average path velocity)≥25%,the sperm motility of six parts of boar semen was tested at normal temperature using different brands of special fixed-volume slides with a uniform chamber height[(20±2)μm].There were no significant differences in sperm vitality detected by the five CASA systems(P>0.05).The ZB scores of the vitality obtained by observers or instrument engineers who did not have a job certificate from the quality inspection department showed that the results of three observers or instrument engineers were unsatisfactory(∣ZB∣>3),but there were no significant differences in vitality between the CASA systems and the inspector with a job certificate(P>0.05).Regarding sperm density detection,when the sperm density was less than 280×106/ml,there were no significant differences between the results displayed by the instruments and the results of the manual hemocytometer counting(P>0.05).[Conclusions]The accuracy of the CASA systems set to uniform parameters was consistent with the accuracy of the visual vitality obtained by an inspector with a job certificate.When the semen was diluted with 3%NaCl solution to a sperm density<280×10^6/ml,the sperm density detected by the CASA systems was consistent in reliability with that obtained by the hemocytometer detection.The CASA systems are faster and more efficient and objective than manual detection,and have the advantages of strong operability and easy promotion.

Serologic and molecular survey for major viral pathogens in grazing hybrid wild boars in Northeast China

Hybrid wild boar husbandry is an important component of livestock production in Northeast China.However,the current disease situation of these animals is largely unknown due to a lack of disease surveillance.The present study was conducted to determine the prevalence of several important viral diseases in the hybrid wild boar population of Northeast China.Between September 2015 to December 2016,169 blood and 61 tissue samples were collected from apparently healthy hybrid wild boars from farms in Jilin,Inner Mongolia and Heilongjiang provinces.ELISA detected serum antibodies against classical swine fever virus(CSFV),porcine reproductive and respiratory syndrome virus(PRRSV),pseudorabies virus(PRV),porcine circovirus type 2(PCV2)and Japanese encephalitis virus(JEV),but not against African swine fever virus(ASFV),with PCV2 having the highest seropositive rate(87.2–100%in different farms).RT-PCR or PCR performed on the processed samples detected only PCV2,with 33.1%(56/169)of blood samples and 32.8%(20/61)of spleen samples being positive,respectively,indicating widespread PCV2 infection in hybrid wild boars.Phylogenetic analysis of 15 PCV2 ORF2 sequences showed that they belong to genotypes PCV2a,PCV2b and PCV2d,with nucleotide and deduced amino acid homologies of 88.5–100%and 88.1–100%,respectively.

Identification of Toll-like Receptor (TLR) 4 Gene in Wild Boar

Toll-like receptor （TLR） 4 plays an important role in the innate immune system and has been involved in resistance/ susceptibility to a number of diseases as revealed by studies in human and other domestic animals. Wild boar survives in natural environment without artificial interference and may be different from domestic pig in innate immune system. Here, the complete coding sequence of TLR4 and TLR4A was cloned in wild boar, and two other alternative splicing variants, TLR4B and TLR4C, were obtained. Compared to the counterpart from domestic pig （GcnBank No. AJ628065）, there were five SNPs, c.510T〉C, c.960A〉G, c.962A〉G, c.1605T〉G and c.1824A〉G, in the coding sequence of wild boar TLR4A gene. TLR4 gene was expressed in all the tissues from wild boar studied with the most abundance in spleen tissue, and mRNA level was significantly lower in spleen from wild boar than that from Min pig. The allele distribution was significantly different at polymorphic loci c.962G〉A and c.1027C〉A （p〈0.01） between wild boar and Min pig. The results would contribute to understand the innate immune system in wild boar.

Effects of Three Different Diluents on Quality of Boar Semen Stored at 17℃

To investigate the effects of different diluents on the quality of the boar semen stored at 17℃, and assess the relationship between sperm motility and the relative levels of enzymes, three commercial diluents （Diluent I, Diluent II and Diluent III） and three boar breed semens （Yorkshire, Landrace and Duroc） were utilized. The sperm motility, effective survival time, survival index, catalase （CAT）, the total anti-oxidative capacity （T-AOC） and malondialdehyde （MDA） levels were evaluated. The results showed that there were significant interaction effects between diluents and breeds on the boar sperm motility （P〈0.001）, survival time （P〈0.001）, CAT levels （P〈0.001） and T-AOC levels （P〈0.001）, but neither effects nor interaction effects between diluents and breeds on survival index （P〉0.05）. All of the parameters varied significantly with the increase of the storage time （P〈0.001）. The survival time increased 12.9% in Yorkshire boar semen diluted with Diluent III than with Diluent II, while the survival time increased 6.6% in Landrace boar semen diluted with Diluent II than with Diluent III. Both CAT and T-AOC levels were significantly positive correlated with sperm motility in all the three boar breeds （P〈0.001）, while MDA levels were significantly negative correlated with sperm motility （P〈0.001）. These results indicated that Diluent III and Diluent II were the optimal commercial diluents for Yorkshire and Landrace boar semen stored at 17 ℃, respectively.

Genetics Research and Advance on Development and Utilization of Wild Boars

Wild boar is one of the most important beast resources. It plays an important role in the maintenance of biological diversity. The genetic resources of wild boar can not only protect the genetic resources, but also improve the formation of new breeds in pigs. This paper summarized the advance on the main biological characteristics of wild boars, evolutionary origin between wild boars and domesticated pigs, and development and utilization of wild boars aimed to provide further insight into wild boar＇s genetic research and its resource protection.

Correlation of Evaluation Methods on Boar Semen Quality

To explore the correlation of evaluation methods on boar semen quality, the motility, PI staining, hypotonic swelling test, Rh123 staining and FITC- PNA staining of boar sperm were checked in the study, and its correlation with IVF was statistically calculated. The results showed that various indicators had strong linear correlation with each other, and the correlation degree between acrosome integrity and IVF rate was the highest, indicating that acrosome integrity was supedor to other indicators in predicting IVF rate.

Effects of Selenium-Enriched Probiotics on Semen Quality of Stock Boars

Selenium-enriched probiotics were supplemented into feedstuff of Landrace stock boars at a concentration of 0.3 mg/kg （concentration of selenium）, and the semen quality of the stock boars were observed. The results showed that the semen motility, rate of intact acrosome, and activity of glutathione peroxidase were higher in the experimental boars than in the control, but rate of sperm deformity was lower in the experimental boars than in the control. Therefore, the selenium-enriched probiotics greatly improve semen quality of stock boars.

Effect of Cryopreservation on DNA Integrity and Morphological Structure of Boar Sperm

The paper was to explore the effect of cryopreservation on DNA integrity and morphological structure of boar sperm, and to explore the protective effect of trehalose and lactose on frozen boar sperm. The morphology, ultrastructure and DNA integrity of sperms were observed by phase contract microscope, scanning electron microscope （SEM） and acridine orange （AO） staining, respectively. The results showed that the normal morphological rate and DNA integrity rate of fro- zen sperms were significantly lower than that of fresh sperms （95.5% and 94.7%, respectively）, and the difference between two frozen groups was also significant （P 〈 0.05 ）. The normal morphological rates in trehalose group and lactose group were 74.7% and 67.6%, while DNA integrity rates in trehalose group and lactose group were 66.4% and 63.2%, respectively. The common deformations of frozen sperms under SEM were partial or complete fracture between head and neck, swollen neck_ dama=ed aemsome stnJetn~.