Lysozyme， a naturally occurring multifunctional protein， exerts antibacterial effects through peptidoglycan（PG） hydrolysis and a cation ? dependent，non ? enzymatic mechanism. It also possesses antiviral properties by binding to cellular receptors or viral particles，thereby inhibiting viral entry，sequestering viral nucleic acids，and inhibiting virus?induced cell fusion. These mechanisms contribute to its broad application value across diverse fields such as food preservation，adjunctive medical therapy，and livestock production. Antibiotics are widely used in livestock production to treat bacterial infections，boost animal immunity，and reduce the risk of disease transmission. However，the overuse or misuse of antibiotics can lead to bacterial resistance，drug residues，and potential health risks. Therefore，lysozyme，as a promising alternative，holds great potential in promoting the transition to antibiotic?free，sustainable livestock production. This review provides an overview of the antibacterial and antiviral mechanisms of lysozyme，along with the latest research on its applications in livestock production. It also addresses the technical challenges and limitations encountered in its practical use. The aim is to offer a theoretical basis for the scientific application of lysozyme in the healthy farming of livestock and poultry and to facilitate its industrial development as an antibiotic alternative.

The aim of this study was to detect candidate genes affecting the weaning ? to ? service interval of Landrace sows through the genome?wide association analysis（GWAS），in order to provide theoretical references for swine breeding in China. In this study, the weaning?to?service interval records and 50K gene data of 1 063 Landrace sows in a core breeding farm in China were used as research materials, and genome ? wide association analysis was performed by mixed linear models of GEMMA software to identify important loci. The results showed that there were 5significant SNPs in the first and third parity of Landrace sows. Haplotype analysis was performed on the 5 significant locus and 4 haplotype blocks were obtained. The screened genes of BTG1, FUT1, FUT2, SCNN1G, and CBLB may be the important genes affecting the weaning?to?servce interval traits. The results of this study can provide the reference for future practice of swine breeding.

In order to provide evidence for precise prevention and control of Porcine proliferative enteropathy， the prevalence of Lawson Intracellularis in large?scale pig farms under the background of antibiotic?free feed and restricting the use of antibiotics in pig breeding industry was investigated. In this study，nested PCR and indirectELISA were used to detect fecal and serum samples from different pig farms. Under the background of antibiotic?free feed，nested PCR detection was conducted on 695 fecal samples collected from different pig farms. the overall infection rate was 23.88%. The infection rates of nursery pigs，finishing pigs and boars were 16.56%，29.58% and 24.63%，respectively. The results of the follow?up survey of the pig herds with antibiotic?free feed and under the background of restricting the use of antibiotics in pig breeding industry were as follows：the infection rate of nursery pigs at 30，44，58 and 72 days of age was 16.67%，20.00%，50.00% and 70.00%，respectively. The infection rate of gilts ranged from 44.44% to 66.67%. As for the ELISA test results，the positive rate of lawsonia intracellularis was 42.6% in 338 serum samples and the positive rate of Lawsonia Intracellularis range from 10% to 75.90% in pig farms from different provinces. The aboved results showed that the prevalence of Lawsonia Intracellulare in large?scale pig farms in China were at a high level at present. The highest infection rates of nursery pigs and gilts were 70% and 66.67% respectively. The infection rate of nursery pigs increased significantly with the increase of age. Therefore，it is necessary to pay more attention to the prevention and control of porcine proliferative enteropathy in large?scale pig farms under the background of antibiotic?free feed.

In order to establish a rapid detection method for Enzootic nasal tumor virus of goats（ENTV ? 2）， primers and TaqMan probes were designed according to the conserved region of ENTV?2 env gene. By optimizing the reaction conditions，the ENTV ?2 TaqMan fluorescence quantitative RT ?PCR detection method was established，and its specificity，sensitivity，repeatability and clinical detection effect were verified. The results showed that the standard curve established by this method had a correlation coefficient（R2 ）of 0.998 when the concentration of recombinant plasmid was 1.019×109 —1.019×102 copies/μL，and the Ct value had a good linear relationship with the concentration of recombinant plasmid. This approach was specific for ENTV ? 2，and there was no cross ? reaction observed against other five kinds of pathogens related to goats. The minimum detection limit was 10.19 copies/μL，andthe coefficient of variation intra ?assays and inter ?assays was within 0.46% and 1.5%. It was more sensitive than the conventional RT?PCR and gave higher ENTV?2 positive detection rate（60%，12/20）than the conventional RT?PCR （30% ，6/20）from clinical samples，the total coincidence rate of the two methods was 70%（14/20）.These data indicated that the TaqMan ? based realtime RT ? PCR assay established here was an effective method with high sensitivity，specificity and reproducibility for faster and more accurate detection and quantification of ENTV?2.