[Objective] To investigate the effects of 17α-methyltestosterone （MT） on relative expression of DNA methyltransferase （DNMT） genes in testis of Gobiocypris rarus. [Method] Male Gobiocypris rarus were treated with varied doses of MT （25, 50, and 100 ng / L）. On the 7^th, 14^th and 21^st day post MT exposure, ten fishes were randomly selected from each MT treatment group, respectively, and they were dissected to collect testis tissues. The total RNA in the obtained testis tissues was extracted by one-step Trizol method, and the relative expression of DNA methyltransferase genes （dnmts） was detected by real-time quantitative PCR （qRT-PCR）. [Result] On 7^th day post MT exposure, compared with control group, the relative expression of dnmt3 gene in testis tissues in 25 ng/L （P<0.05）, 50 ng/L （P<0.01）, and 100 ng/L （P<0.05） MT treatment groups was significantly or extremely significantly reduced; in the testis tissues of 25 ng/L and 50 ng/L MT treatment groups, the relative expression of dnmt5 gene fell significantly （P<0.05）; 50 ng/L MT treatment group had significantly （P<0.05） decreased relative expression of dnmt7 gene in the testis tissues. On 14^th day post MT exposure, compared with control group, the relative expression of dnmt3, dnmt5, dnmt6, and dnmt7 genes increased significantly （P<0.05） in 100 ng/L MT treatment group, and that of dnmt1 gene increased extremely significantly （P<0.01） in 50 ng/L MT treatment group. On 21^st day post MT exposure, compared with control group, 50 ng/L and 100 ng/L MT treatment groups had significantly （P<0.05） increased relative expression of dnmt1 gene, and 100 ng/L MT treatment group had extremely significantly （P<0.01） higher relative expression of dnmt8 gene. [Conclusion] MT can interfere with the mRNA expression of dmmts genes in testis of Gobiocypris rarus. Further studies are expected to focus on the effects of MT on enzymatic activity of DNA methyltransferases, as well as on whether MT affects spermatogenesis of Gobiocypris rarus by altering DNA methylation levels.

In recent years, researchers have discovered that animals contain a type of non-self-derived miRNA, which were always ingested by food and have regulatory functions in animals. These findings may provide some theoretical foundations for extracting specific compounds from plants as additives or investigating the mechanisms underlying the therapeutic role of Chinese herbal medicine. They also broaden the research scope of exogenous animal and plant miRNA. From the aspects of formation process, structural characteristics, stability post cross-kingdom, tissue-specific expression, target gene binding mode, biological function, and cross-kingdom regulation, this paper systematically illustrated the mechanisms underlying the cross-kingdom gene regulation of animal and plant miRNA, reviewed corresponding research progress, and forecasted future research directions and applications of animal and plant miRNA, in hoping to serve as a guide for the development and utilization of miRNA in disease treatment and nutritional supplementation.

Oxidative stress in livestock and poultry is defined as an imbalance between the production of reactive oxygen species and the elimination of protective mechanisms, which can lead to oxidative damage in tissues and eventually induce inflammatory diseases. Oxidative stress activates a variety of transcription factors, resulting in the differential expression of genes associated with inflammatory pathway. Inflammation induced by oxidative stress is the cause of many chronic diseases. Polyphenols are secondary plant metabolites which have been considered to be effective adjuvants for adjuvant therapy and shown to exert potential antioxidant and anti-inflammatory effects in humans and animals. Polyphenols are also considered to be a promising feed additive for livestock and poultry. In this paper, the relationship and mechanism between oxidative stress and inflammation in livestock and poultry, as well as the antioxidant and anti-inflammatory effects of polyphenols in livestock and poultry and their underlying mechanisms are reviewed, in hoping to provide references for application of antioxidant therapy of animal diseases and development of new anti-inflammatory drugs.

The emergence of ′superbug′ with high antimicrobial resistance poses a serious threat to human and domestic animal health. The fundamental cause of ′superbug′ is extensive and high-frequency usage of limited categories of antimicrobial agents for the treatment of bacterial infectious diseases in humans, domestic animals, and pets. One of the hottest research areas right now is discovering alternatives or enhancers for existing conventional antibiotics. Researchers have found the antibacterial characteristics of mesenchymal stem cells （MSCs）. Theoretically, MSCs have the potential to be developed as an effective means for the treatment of bacterial infectious diseases. This paper reviews the research progress in the mechanisms underlying the effects of MSCs on bacterial survival and in the possible impacts of antibiotics on MSCs functions, in hoping to provide references for further clarifying the antibacterial action mechanisms of MSCs and exploring the potential of MSCs as a novel means for therapy of bacterial infectious diseases.

[Objective] To investigate the effects of microbial fermented expanded straw feed on growth performance and gastrointestinal tract development of Dorper and Thin-tailed Han crossbred sheep. [Method] A total of 81 3-month-old Dorper and Thin-tailed Han crossbred sheep weighing （23.0±1.0） kg were chosen and randomly assigned into the following three groups: control group （70% concentrate + 30% dry straw）, experimental group Ⅰ（70% concentrate + 30% microbial fermented expanded straw feed）, and experimental group Ⅱ （70% concentrate + 30% microbial fermented expanded straw feed, supplemented with expanded slow-release urea accounting for 10% of the total dietary protein concentration, NPN≥100%）. The experiment lasted for 75 days, with a 15-day pre-feeding period and a 60-day formal feeding period. The weight gain of the fattening sheep during the experiment was evaluated, and the gastrointestinal tract tissues were weighted and morphologically characterized. [Result] The feed intake and daily weight gain in experimental groups Ⅰ and Ⅱ were extremely significantly （P<0.01） boosted by the microbial fermented expanded straw feed. The weight of the large intestine, the total weight of the digestive tract, and the rumen volume were significantly （P<0.05） increased in experimental groups Ⅰ and Ⅱ compared with those of control group. The color of the rumen internal wall was better in experimental group Ⅱ than that in the other groups. [Conclusion] The microbial fermented expanded straw feed promotes the growth performance and gastrointestinal tract development of fattening sheep, with experimental group Ⅱ having a stronger effect.

[Objective] To assess the impacts of feeding frequency on backfat thickness and reproductive performance in pregnant sows. [Method] A total of 480 multiparous Duroc sows were selected and randomly divided into two groups （T1 and T2） according to the principle of similar parity （2^nd -7^th） and backfat thickness （11-22 mm） before artificial insemination （AI）. T1 group sows （n=220） fed once per day, and the feeding time was 8:00. T2 group sows （n=260） fed twice per day, and the feeding time was 8:00 and 15:00, respectively, with half of the total amount of diet each time. Both groups fed the same amount each day. The experimental sows were housed in individual crates.[Result] ①Feeding frequency had no significant （P>0.05） effects on backfat thickness on 56^th day of gestation and the difference of backfat thickness between day of AI and 56^th day of gestation （backfat thickness on 56^th day of gestation minus that on day of AI） . A trend of increase in backfat thickness on 110^th day （P=0.06） of gestation and the difference of backfat thickness between 56^th day and 110^th day （P=0.09） of gestation （backfat thickness on 110^th day minus that on 56^th day of gestation） in T2 group was observed in comparison to T1 group. ② There were no significant （P>0.05） effects of feeding frequency on the total number of piglets per litter, number of live piglets, number of stillborn piglets, number of mummified fetus, litter weight at birth, and individual birth weight. ③ For the third-parity sows, backfat thickness on 110^th day （P=0.01） of gestation and the difference of backfat thickness between 56^th day and 110^th day （P=0.04） of gestation in T2 group was significantly higher than those in T1 group. For sows with five and above parities, an increasing trend in the difference of backfat thickness between 56^th day and 110^th day （P=0.08） of gestation in T2 group was also found in comparison to T1 group. ④ Feeding frequency had no significant （P>0.05） effects on second-parity sows in terms of total number of piglets per litter, number of stillborn piglets, number of mummified fetus, litter weight at birth, and individual birth weight, while second-parity sows in T2 group had higher number of live piglets than those in T1 group （P=0.07）. [Conclusion] Reducing feeding frequency from twice to once per day had no negative impacts on reproductive performance of sows.

[Objective] To determine the best process parameters for preparing pelletized supplementary concentrate of cow and sheep by combinatorial use of a concentrate blender （JB-300 type） and a flat die granulator （300 type）. [Method] The impacts of varied mixing times and loading coefficients on feed blending uniformity were examined. Based on the determined process parameters of blending and mixing, the effects of different corn particle sizes and moisture contents on the molding rate of pelletized feed were assessed. To determine the best combinatorial parameters for preparing pelletized feed, the die hole diameter, corn particle size, and moisture content were used as base measurement factors, and the comprehensive weighted score of molding rate and hardness were used as evaluative index in orthogonal test. [Result] When the blending time was set to 10 min or 20 min, the variation coefficients were significantly （P<0.05） lower than when it was set to 5 min or 15 min. The variation coefficient was significantly lower （P<0.05） when the loading coefficient was 80% than when it was 70% or 60%. The molding rate of pelletized feed was significantly （P<0.05） higher when the corn particle size was 2 mm or 4 mm than when it was 6 mm or 8 mm. When the moisture content was 10% or 13%, the molding rate of pelletized feed was significantly （P<0.05） higher than when it was 16% or 19%. The extreme differences of die hole diameter, corn particle size and moisture content affecting the comprehensive weighted average score of orthogonal test were 18.76, 1.64 and 3.47, respectively. [Conclusion] The optimal parameters of the JB-300 type concentrate blender for feed mixing were loading at 80% and mixing for 10 minutes. The die hole diameter of 4 mm （compression ratio of 6）, corn particle size of 4 mm, and moisture content of 13% were the best specifications of the 300 type flat die granulator for preparing pelletized supplementary concentrate.

[Objective] To determine the primary causes of sickness and mortality in Mongolian sheep lambs in Gobi grassland in northern Sonid Left Banner, Inner Mongolia, throughout the spring. [Method] Samples were taken from three family livestock farms with the most diseased lambs. Blood samples were taken from five diseased lambs from each farm. Samples of drinking water in grazing pastures were collected. Further more, three main forages （Reaumuria soongarica, Salsola passerina, and Kalidium foliatum） and soil samples from the lambs′ habitat were taken as well. Samples from 15 healthy lambs of the same breed were obtained as controls from a local breeding sheep farm. The concentrations of ten mineral elements （calcium, phosphorus, iron, manganese, copper, zinc, magnesium, molybdenum, selenium and cobalt） in above samples were analyzed. [Result] Copper and magnesium concentrations in diseased lambs′ blood were significantly lower （P<0.05） than those in healthy lambs of the same breed, whereas molybdenum concentrations were significantly higher （P<0.05）. The concentrations of the other mineral elements did not differ significantly （P>0.05）. In the surroundings of the diseased lambs, the levels of magnesium and calcium in drinking water were higher. The levels of molybdenum, iron, manganese, and selenium in Reaumuria soongarica were higher than those described in the literature, whereas the levels of the other mineral elements were within normal limits. The levels of molybdenum, iron, manganese, selenium, magnesium, and cobalt in Kalidium foliatum were above those reported in the literature, whereas the contents of the other mineral elements were within normal limits. In Salsola passerina, Reaumuria soongarica and Kalidium foliatum, the ratios of copper to molybdenum were 15.96∶1, 0.23∶1, and 2.34∶1, respectively. The levels of copper, iron, manganese, selenium, and cobalt in the soil samples from the diseased lambs′ habitat were lower than those described in the literature, magnesium, calcium, and phosphorus levels were higher, and molybdenum and zinc levels were within normal limits. [Conclusion] Insufficient copper intake is the leading cause of sickness and mortality in Mongolian sheep lambs in Gobi grassland. Exceeded molybdenum as well as excessive intake of iron, manganese and some other mineral elements cause the malabsorption of copper by lambs, leading to secondary copper deficiency.

Mulberry leaf, as an unconventional animal feed resource, has rich nutrients and active substances. It is of positive significance to improve growth performance, immunity and product quality of animals. This paper reviews the nutritional value and feeding value of mulberry leaf, and summarizes the application status of mulberry leaf in diets preparation for poultry, livestock, fish and other animals, aiming to provide references for the further application and development of mulberry leaf in animal feed.

Salix psammophila is a shrub plant with functions of windbreak, sand fixation and soil conservation. In the development of unconventional feed resources in China, it is also a novel fodder resource with distinctive feeding value. It has high stress tolerance, large quantity, widespread distribution, low price, and rich nutrients. This paper reviews the ecological characteristics as well as ecological and economic value of Salix psammophila, and summarizes its feeding value and nutritional components. In addition, the feed treatment methods and processing technologies of shrub plants represented by Salix psammophila are generalized, the major challenges with feed utilization of shrub plants are examined, and effective approaches for their development and utilization are proposed, in hoping to provide references for the development and feed utilization of Salix psammophila and other shrub plants.

[Objective] To assess the applicability of an integrated mode of breeding technologies in mutton sheep of imported breeds, such as continual and repeated superovulation, embryo flushing, and embryo transplantation. [Method] From the year of 2016 to 2018, a total of 1 575 imported mutton ewes belonging to five breeds, including Australian White （n = 230）, White Dorper （n=228）, Dorper （n=541）, White Suffolk （n=200） and Suffolk （n=376）, were treated by continual estrus synchronization （progesterone sponge） and superovulation （330-450 IU FSH + 200-300 IU PMSG + 0.1 mg PG） with an interval of more than 30 days. Intraperitoneal endoscopic insemination was performed to flush out embryos from uterine horn of the ewes. The obtained embryos were counted, evaluated in terms of quality, and then partially transplanted into the synchronized receptors. The impacts of breed, season, and number of repeated superovulation times on embryo productivity were compared and analyzed. [Result] A total of 18 496 embryos were obtained, with 14 971 transferable ones. Gestation rate after embryo transplantation was 69.8% and the lambing rate was 93.2%. According to the mean numbers of recovered total embryos and transferable embryos per ewe, the embryo productivity of White Suffolk, Suffolk and Dorper was superior to Australian White, and White Dorper had the worst performance. After continual and repeated superovulation as well as embryo collection, the mean numbers of recovered total embryos and transferable embryos per ewe of different breeds continued to increase until the 4^th or 5^th treatment. The outcome of superovulation and embryo collection of Australian White was better in spring, while the other breeds were better in winter. [Conclusion] Continual and repeated superovulation as well as embryo collection are feasible breeding technologies for propagation of the mutton sheep of imported breeds. They should be used in a scientific and timely manner, taking into account the various breeds and their seasonal reproductive features.

[Objective] To screen the high quality and high yield alfalfa（Medicago sativa）cultivars suitable for local production conditions in Jiuquan area of Gansu Province. [Method] In Shangba Town, Suzhou District, Jiuquan City, Gansu Province, a total of 57 alfalfa materials from various ecological zones were sown. In the early squaring stage, diversity analysis and comprehensive evaluation of agronomic traits and yields were performed, followed by correlation analysis and principal component analysis among agronomic traits, cluster analysis, and comprehensive evaluation of membership function. [Result] The 57 alfalfa cultivars were divided into four categories. The cultivars with the lowest yield and comprehensive ranking were in the first category, and the ones with the highest were in the second category. The third category included materials with a high yield but poor in other indexes. The fourth category included the cultivars with moderate performance in yield and comprehensive ranking. [Conclusion] In this area, the alfalfa cultivars with better comprehensive assessment outcomes in the planting year are Zhongmu NO.3, North SLT, SR4030, and WL343HQ.

[Objective] To assess the effects of simulated drought stress with polyethylene glycol （PEG） on seed germination of Lespedeza davurica, Medicago ruthenica, and Coronilla varia. [Method] PEG solutions with concentrations of 0, 5%, 10%, 15%, 20% and 25% were used to simulate drought stress, and the seed germination experiments of the above three leguminous forage species were conducted. The germination percentage, germination index, mean germination time, and seedling vigor index of their seeds were analyzed, and their drought resistance were comprehensively evaluated to explore the germination properties under drought stress. [Result] The germination percentage, germination index and seedling vigor index of Lespedeza davurica and Medicago ruthenica seeds significantly （P<0.05） declined with the aggravation of drought stress, but their mean germination time significantly （P<0.05） increased. When PEG concentration reached 25%, the Lespedeza davurica seeds lost their vigor. The germination percentage, germination index and seedling vigor index of Coronilla varia seeds were significantly （P<0.05） higher than those of the control at 5%-10% of PEG concentrations, then dropped as the PEG concentrations increased. The comprehensive evaluation by membership function method demonstrated that the order of drought resistance of the three tested leguminous forage species at seed germination stage was Coronilla varia > Medicago ruthenica > Lespedeza davurica. [Conclusion] Simulated drought stress with PEG inhibits the germination of Lespedeza davurica and Medicago ruthenica seeds. PEG at low concentrations （≤10%） promote the germination of Coronilla varia seeds, however, higher concentrations （≥15%） have the reverse effect. Coronilla varia seeds have a stronger germination capacity in comparison with Medicago ruthenica and Lespedeza davurica seeds under drought stress.

[Objective] To assess the physiological response and differential changes of the activities of antioxidant enzymes in feed oat （Avena sativa） to nitrogen fertilizer at the northern foot of Yinshan Mountain, and to determine the optimal nitrogen fertilizer application rate. [Method] Using feed oat species ′Sanxing′ as the material, the nitrogen fertilizer application rates of 0, 150, 200, 250, 300 and 350 kg/hm² were set, and additional 15%, 35%, 30%, and 20% of the nitrogen fertilizer was applied at seedling stage, tillering stage, jointing stage, and booting stage for each nitrogen fertilizer application rate, respectively. The activities of three types of antioxidant enzymes and the level of malondialdehyde （MDA） in feed oat leaves were evaluated at booting stage, heading stage and grain filling stage. [Result] As the increase of nitrogen fertilizer application rates, the activities of superoxide dismutase （SOD）, peroxidase （POD） and catalase （CAT） in feed oat leaves at booting stage, heading stage, and grain filling stage increased first and then declined, and the level of MDA reduced progressively. At all of the three observed growth stages, the highest POD activity in feed oat leaves was found at the nitrogen fertilizer application rate of 250 kg/hm². At booting stage and grain filling stage, feed oat leaves had the highest SOD activity at the nitrogen fertilizer application rate of 250 kg/hm². The highest CAT activity was observed at the nitrogen fertilizer application rate of 300 kg/hm² at booting stage and heading stage, and at grain filling stage, that was observed at the nitrogen fertilizer application rate of 250 kg/hm². [Conclusion] At the northern foot of Yinshan Mountain, lower application rate of nitrogen fertilizer enhances the activities of antioxidant enzymes in feed oat, and higher rate exerts the reverse effect. The appropriate nitrogen fertilizer application rate is 250 kg/hm².

[Objective] To assess the effects of various disinfection durations, straw substrates, and layout methods on substrates mildewing as well as germination and seedling growth of wheat and corn grains, aiming to optimize the use of straw as a substrate material for fresh grass production and to lower the cost of large-scale fresh grass production. [Method] Using wheat and corn grains as experimental materials, the mildewing status of substrate materials after different durations of disinfection by boiling was observed, and the germination rate, germination potential, and germination index of wheat and corn grains in different substrate materials were investigated. Furthermore, the impacts of various layout methods, particle sizes, and material ratios on seedling growth height were evaluated. [Result] As substrate materials, Artemisia and reed straws required a disinfection for 30 minutes and 60 minutes, respectively, and maize, millet, soybean, and Caragana straws required a disinfection for 120 minutes. Compared with the filter paper, the straw substrates of maize, millet, soybean and reed had no significant （P>0.05） changed germination rate, germination potential, and germination index of wheat and corn grains. The inside-substrate layout method had higher height of wheat and maize seedlings than the other layout methods. There was no significant （P>0.05） difference in height of wheat and maize seedlings treated with coarse flour or fine flour substrate materials on 10^th day of growth. On 3^rd, 7^th, and 10^th day of growth, no significant （P>0.05）difference in wheat seedling height was observed under different material ratios. There was no significant （P>0.05） change in maize seedling height under different material ratios during the whole experiment. [Conclusion] In industrialized fresh grass production, it is preferable to use maize, millet, soybean, and reed straw as substrate materials. Prior to production, the substrate materials must be boiled for disinfection for at least 120 minutes. Fresh grass production may achieve a better performance with the inside-substrate layout method, straw particle length of roughly 2 cm, a material ratio of 3∶1 for wheat, and a material ratio of 4∶1 for maize.

[Objective] To assess the effects of mustard crude polysaccharides on texture property and oxidative stability of beef emulsion. [Method] Additions of 0.5% and 2.5% mustard crude polysaccharides to the basal formula of beef emulsion were set as two experimental groups, respectively, and those of carrageenan and butyl hydroxy anisd （BHA） was used as controls in the tests of texture property and oxidative stability, respectively. After a storage at 4 ℃ for 20 days, the hardness, resilience, gumminess, chewiness, and thiobarbituric acid reactive substances （TBARS） value, total sulfhydryl content, carbonyl content, pH value, and chromaticity value of the beef emulsion in each group were determined, and the inter-group differences of the tested indicators were statistically analyzed. [Result] Similar to carrageenan, the addition of 0.5% mustard crude polysaccharides significantly （P<0.05） improved the hardness, resilience, gumminess, and chewiness of the beef emulsion, while the addition of 2.5% mustard crude polysaccharides had no significant （P>0.05） influences on the above four parameters associated with texture property. The addition of 0.5% mustard crude polysaccharides significantly （P<0.05） reduced the TBARS value of the beef emulsion, slowed down the increase of malondialdehyde （MDA） content, and inhibited the fat oxidation. The addition of 2.5% mustard crude polysaccharides significantly （P<0.05） limited the increase of pH value, slowed down the reduction of total sulfhydryl, and alleviated the deterioration of the redness to some degree. However, it had poor performance in preventing the formation of carbonyl compounds. [Conclusion] Mustard crude polysaccharides not only improve the texture property of beef emulsion but also alleviate the oxidation and maintain a consistent color. The findings obtained in this study may provide references for using mustard crude polysaccharides as novel natural antioxidant in beef products.

[Objective] To assess the effects of overturning of three green manure crops, Lolium multiflorum, barley and oilseed rape, on soil quality under irrigation with varied concentrations of biogas slurry. [Method] Under two biogas slurry concentrations, 8.5 L/m² （L1） and 17 L/m² （L2）, the green manures of Lolium multiflorum, barley and oilseed rape were applied, respectively. Under L1 biogas slurry concentration, experimental groups of Lolium multiflorum （L1）, barley （L1）, oilseed rape （L1） were set, and a control group of CL1 with biogas slurry irrigation without application of green manures were included. Under L2 biogas slurry concentration, experimental groups of Lolium multiflorum （L2）, barley （L2）, oilseed rape （L2） were set, and a control group of CL2 with biogas slurry irrigation without application of green manures were included. The differences in pH value as well as contents of organic matter and total nitrogen in soil were statistically analyzed among groups with the same biogas slurry concentration and the different varieties of green manures. [Result] After 110 days of green manures application, the soil pH value of Lolium multiflorum （L2） and barley （L2） groups was significantly （P<0.05） higher than that of CL2 group, with a mere 0.17 rise. The soil salinity of barley (L1) and Lolium multiflorum （L2） groups was significantly （P<0.05） higher than that of CL1 and CL2 groups, respectively. The content of soil organic matter of the two barley groups was significantly （P<0.05） higher than that of their respective control groups. The content of soil organic matter of oilseed rape （L2） group was also significantly （P<0.05） higher than that of CL2 group. The soil total nitrogen content of the two barley groups was significantly （P<0.05） higher than that of their respective control groups. The soil available phosphorus content of Lolium multiflorum （L1） and barley （L1） groups was significantly （P<0.05） higher than that of CL1 group. The soil available potassium content of barley （L2） group was significantly （P<0.05） higher than that of CL2 group. [Conclusion] The application of three varieties of green manures has different effects on soil improvement after biogas slurry irrigation. Barley significantly increases the soil contents of organic matter and total nitrogen when nitrogen fertilizer is replaced by both concentrations of biogas slurry. In addition, barley greatly increases the content of soil available phosphorus under low biogas slurry concentration, and significantly increases the content of soil available potassium under high biogas slurry concentration, suggesting that it can be utilized as a new type of green manure.

With the large-scale and intensive development of animal husbandry, livestock and poultry breeding has become one of the main sources of agricultural non-point source pollution in China. The resource utilization of livestock and poultry manures is not only critical for ensuring the healthy and sustainable development of animal husbandry, but it is also a vital step toward achieving the long-term goal to construct ecological civilization and build a community with a shared future for mankind from the perspective of sustainable development. The ability to achieve coordination and unity in livestock and poultry pollution management and economic development is made possible by the agricultural production mode of planting-breeding combination. Through analyzing the origins of greenhouse gases in production, processing and consumption of animal husbandry, this paper summarizes the general solutions of source reduction, process control, and end treatment of livestock and poultry breeding, in hoping to provide references for farm households, animal breeding enterprises, and local governments with similar characteristics, to improve the resource utilization efficiency of livestock and poultry manures, and to promote carbon neutrality in animal husbandry.

Amoxicillin （AMO） is one of the semi-synthetic β-lactamic antibiotics. It is widely used in veterinary clinic due to its strong acid resistance, good bactericidal effect, broad antibacterial spectrum, high water solubility, and various dosage forms. This paper reviews the physical and chemical properties, antibacterial mechanism, safety, and applicability in treatment of animal infectious diseases of AMO, in hoping to offer references for its scientific and rational use in veterinary clinic.

[Objective] To determine the etiologic agent causing the suspected cases of contagious ecthyma （orf） in large-scale sheep farms in Inner Mongolia. [Method] A total of 7 clinical samples were aseptically collected from the diseased sheep with suspected orf symptoms, and they were subsequently inoculated with goat skin fibroblasts （GSFs） for virus isolation after cutting, grinding, and centrifugation. The obtained viral strains were morphologically observed by electron microscope. B2L gene primers were used for specific PCR identification, and the product was then sequenced. The phylogenetic tree based on B2L gene was constructed, and homology analysis was performed as well. [Result] There were 3 clinical samples with capacity to cause evident cytopathic alterations in GSFs after inoculation for 48 hours. Morphological observation with electron microscope demonstrated that the isolated virus was oval in shape, and the viral particles were 220-250 nm long and 125-200 nm wide, which were consistent with the morphological characteristics of orf virus （ORFV）. The 3 obtained ORFV strains were designated as NM-ORFV-1, NM-ORFV-2, and NM-ORFV-3, respectively. For each isolated viral strain, a product of 1 137 bp was amplified by PCR assay targeting B2L gene, which was consistent with the expecting size. Phylogenetic tree and homology analysis revealed that NM-ORFV-2 strain was closely genetically related to NM-ORFV-3 strain, and they clustered in the same branch; NM-ORFV-2 strain shared the highest homology （99.4%） with ORFV KP336704（China）wild strain; NM-ORFV-1 strain clustered in different branch from NM-ORFV-2 strain and NM-ORFV-3 strain, and the homologies of NM-ORFV-1 strain shared with NM-ORFV-2 strain and NM-ORFV-3 strain were 99.1% and 99.0%, respectively; NM-ORFV-1 strain shared the highest homology （99.6%） with ORFV JQ904789（China）vaccine strain. [Conclusion] ORFV is identified as the pathogenic agent that causes the suspected cases of orf in large-scale sheep farms in Inner Mongolia.

Mycoplasma pneumonia caused by Mycoplasma ovipneumoniae （MO） is a devastating respiratory disease that puts the sheep industry at risk. MO infection is often insidious and persistent, resulting in reduced productive performance of diseased sheep and serious economic losses in sheep industry. By consulting the recent literature on molecular pathogenic mechanism of MO in China and abroad, we render a review from the following three aspects of adhesion of MO to respiratory epithelial cells, lower respiratory tract injuries caused by MO, and immune suppression induced by MO, in hoping to lay the groundwork for a more in-depth investigation on pathogenic mechanism of MO and for the development of innovative preventative and control strategies.