不同饲养水平对瑶山鸡生产性能和胴体品质的影响

文章旨在研究不同饲养水平对瑶山鸡生产性能和胴体特征的影响。试验将400只平均体重一致的1日龄瑶山鸡随机分为2组,每组4个重复,每个重复50只。2组分别饲喂代谢能水平为3155 Kcal/kg、粗蛋白质水平为225 g/kg的高能高蛋白日粮和代谢能水平为2965 Kcal/kg、粗蛋白质水平为195 g/kg的低能低蛋白日粮。试验共开展10 w。同时将240只产蛋高峰期瑶山鸡随机分为2组,每组4个重复,每个重复30只,饲喂上述日粮4 w,试验结束后收集受精蛋进行孵化。结果:高能高蛋白组种鸡在8和10 w的体重和采食量均显著高于低能低蛋白组(P<0.05),而料重比显著降低(P<0.05)。高能高蛋白组种鸡受精率和孵化率显著高于低能低蛋白组(P<0.05),而残次率、胚胎死亡率和出壳前死亡率显著降低(P<0.05)。1~10 w时高能高蛋白组种鸡体重均显著高于低能低蛋白组(P<0.05),与低能低蛋白组相比,高能高蛋白组屠体重、可食用部分显著升高(P<0.05),腿肌占比显著降低(P<0.05)。结论:中等生长速度的瑶山肉种鸡可以更有效地利用高能量高蛋白(代谢能:3155 Kcal/kg,粗蛋白质:225 g/kg)饲料。     

不同吸附特性的稻草生物炭对稻田氨挥发和水稻产量的影响

秸秆生物炭具有改善土壤生态环境、土壤蓄水保肥和减少温室气体排放等正效应,但其石灰效应会加大稻田氨挥发损失。为充分发挥生物炭吸铵特性,降低其石灰效应的不利影响,对不同热解温度(300、500、700℃)和酸化水平(pH值=5、7、9)稻草生物炭处理下的田面水NH_4~+-N浓度、氨挥发和水稻产量进行了研究。结果表明:偏酸性(pH值=5)、中性(p H值=7)生物炭处理在基肥期和分蘖肥期均能显著降低田面水NH_4~+-N峰值浓度(P0.05),降幅达16.90%～35.60%。全生育期稻田氨挥发损失占施氮量的15.14%～26.05%(2019年)、15.10%～19.00%(2020年)。稻田增施热解温度为700℃、酸化水平为5(p H值=5)的生物炭(C700P5)降氨效果最好,两年氨挥发分别显著降低22.93%、12.61%(P0.05)。高温热解配合偏酸性、中性生物炭(C700P5、C700P7)增产效果显著,增产率达9.92%～13.50%,结构方程模型表明,其增产原因是生物炭酸化处理降低了稻草生物炭的石灰效应,而热解温度调整提高了生物炭阳离子交换量(CationExchange Capacity,CEC),进而降低了田面水NH_4~+-N浓度和氨挥发损失,最终提高了水稻地上部氮素积累和水稻产量。研究可揭示不同热解温度和酸化水平制备的生物炭在稻田中的应用潜力,并为稻田合理施用生物炭和减少化肥施用量提供理论依据。     

Prevention and Controlling Effect of Intercropping on Pests and Diseases and Its Risk Control in Cotton Fields

Cotton is one of the major field crops which are seriously threatened by pests and diseases. In recent years, the ecological management of cotton pests and diseases with intercropping has become to be an interesting approach. Intercropping possibly increases the population of natural enemies and finally reduces the population density of pests as a result of changes in ecological structure and environmental conditions of farmland. Intercropping thus has been considered an important alternative in controlling pests and diseases. However, cotton field intercropping also has some limitations in controlling pests and diseases. Unreasonable intercropping system has many risks such as increasing labor input, increasing the difficulty of pests’ control, and aggravating pests and diseases. In this paper, the effects and the underlying mechanisms of cotton intercropping on cotton pests and diseases were reviewed. The possible risks and countermeasures used for ecological control of intercropping were also put forward, and the future and application of ecological management of cotton pests and diseases with intercropping were prospected.     

Effects of three methionine sources in diets on temporal B0AT1 and ASCT2 mRNA expression in different intestinal segments of cobia,Rachycentron canadum

A 4‐week feeding trial was conducted using five groups of hybrid grouper (61.15 ± 0.15 g) to explore the potential effects of three methionine (Met) sources. Five isonitrogenous and isolipidic diets were formulated that included a fishmeal (FM) diet; nonsupplemented (NS) diet; or NS diets with the addition of the L‐methionine (L‐Met), DL‐methionine (DL‐Met), or coated Met (Co‐Met) to obtain the same Met level as the FM diet. Fish were randomly distributed into sea cages (30 fish per cage). Weight gain and specific growth rate in the DL‐Met group and FM group were significantly higher than those in all other groups (p < .05). In the proximal and distal intestines, of the 20 gene and time combinations (10 per gene), there were 14 combinations (70%) in which there were no significant differences in gene expression levels between the FM and DL‐Met groups (p > .05). The main reason for the same growth effect between the DL‐Met and FM groups may be attributed to the synchronized absorption at most time points after feeding, which had similar expression patterns of B⁰AT1 and ASCT2 of the proximal and distal intestines between two groups.     

优质常规稻品种桂野丰的选育与栽培技术

桂野丰是广西农业科学院水稻研究所育成的感温型常规优质常规稻新品种。该品种粒型长,株型集散适中、剑叶直、分蘖力强、耐寒性较强、茎杆粗壮、抗倒力强、穗长适中、穗大粒多、着粒密、熟期转色好、有特殊的玉兰香味。米质达部颁2级,平均单产442.3~465.6 kg·hm^-2。2017年通过广西壮族自治区农作物品种审定委员会审定,适宜在广西桂北、桂中和桂南作早晚稻种植。     

徐州某规模猪场防疫措施的建立与实施——“五流”生物安全防控

非洲猪瘟在我国流行已有两年多的时间,尽管很多科研团队都在致力于非洲猪瘟疫苗的研发,但尚未有治疗措施和有效的疫苗来控制该病。因此现阶段“生物安全”是控制非洲猪瘟最为有效,也是唯一的方法。文章总结出目前规模化猪场常见的感染风险有“人员流动、物品流动、车辆流动、水源流动、猪群流动”(即“五流”),并提出严格控制“五流”的生物安全防控措施(即“五流”生物安全防控),以减少外界病原与猪只的接触,稀释病原浓度,降低病原载量,最大程度地降低规模化养猪场感染疾病的风险。为当前规模化猪场建立有效的生物安全措施提供参考。     

Administration of probiotic Bacillus licheniformis induces growth,immune and antioxidant enzyme activities,gut microbiota assembly and resistance to Vibrio parahaemolyticus in Litopenaeus vannamei

This study aimed to elucidate the effects of dietary Bacillus licheniformis ATCC 11946 (BL) on the growth, immune and antioxidant activities, intestinal morphology and microbiota, and susceptibility to Vibrio parahaemolyticus (VP_AHPND) in juvenile pacific white shrimp, Litopenaeus vannamei (LV). Juvenile LV (initial weight = 0.63 ± 0.001) were fed diets containing varying BL concentrations (0 (BL0), 10⁶ (BL1), 10⁷ (BL2) and 10⁸ (BL3) CFU/g feed) for 8 weeks. Growth performance, immune and antioxidant enzyme activities, and intestinal morphology significantly improved in the probiotic‐treated groups than the untreated. Regardless of the treatment group, the two dominant phyla were Proteobacteria and Bacteroidetes, whereas the two dominant genera were Ruegeria and Vibrio. Increasing inclusion of probiotics in diets led to significant increase in beneficial bacterial genera (Ruegeria, and Pseudoalteromonas) and a significant decrease in some known opportunistic pathogens (Vibrio, Tenacibaculum, Photobacterium, Kangiella and Spongiimonas) with the BL3 group witnessing the best. A 7‐day challenge study with VP_AHPND showed significantly high protection in the probiotic‐treated groups, with the BL3, BL2 and BL1 obtaining 51%, 34% and 22% relative percentage survival, respectively. In conclusion, BL at 10⁸ CFU/g feed should be used to help in shrimp production since it attained the most significant improvement.     

Effects of antimicrobial peptides on growth,feed utilization,serum biochemical indices and disease resistance of juvenile shrimp,Litopenaeus vannamei

This experiment was conducted to assess the effects of antimicrobial peptides at different levels (Diet 1 (0%), Diet 2 (0.1%), Diet 3 (0.2%), Diet 4 (0.4%), Diet 5 (0.6%) and Diet 6 (1%)), on growth, serum biochemical indices and antioxidant effect, feed utilization and disease resistance in Litopeneaus vannamei. There were four replicates in each group in the experiment (mean weight = 0.21 ± 0.00 g) and also fed with their respective diets for 8 weeks. Growth performance compared with the control group (0%) significantly increased at first and then decreased among treatment groups (p < .05) whereas the survival rate ranged from 78% to 96%. No significant differences were observed in terms of moisture, crude protein and ash content, but there was a significant increase in crude lipid (p < .05). In serum, acid phosphatase, alkaline phosphatase, polyphenol oxidase, triglyceride, glucose and total cholesterol changed as compared with 0%. Total antioxidant capacity, glutathione peroxidase, catalase, superoxide dismutase and malondialdehyde were also different from 0%. Disease resistance was increased in shrimp among treatment groups with 0.4% recording the lowest mortality percentage of 37% after the challenge test. The results from the present study suggested that supplementation of AMP at 0.4% in shrimp diet can improve growth performance, antioxidants activities and innate immune response of Pacific whiteleg shrimp.     

云南、广西三七黑斑病病原链格孢菌的鉴定

正黑斑病是三七栽培生产中常见的一大病害,叶片受害产生近圆形或不规则水浸状病斑,常导致成株落叶、幼苗生长点及茎秆顶端腐烂枯死。其病原一般认为是链格孢属真菌人参链格Alternaria panax Whetzel~([1,2]),也有相关研究证明黑斑病病原为细链格孢Alternaria tenuis Nees~([3]),后定名为链格孢Alternaria alternata Keissl~([4])。本研究利用ITS序列和histone 3部分编码序列的PCR鉴定,结合形态学鉴定,分析三七主产区黑斑病菌的组成和分布情况及几种病原菌的致病力差异,以期为三七黑斑病防治提供理论依据。     

Effects of fish meal replacement by low‐gossypol cottonseed meal on growth performance,digestive enzyme activity,intestine histology and inflammatory gene expression of silver sillago (Sillago sihama Forsskál) (1775)

A 56‐day feeding trial was conducted to evaluate the effects on the growth performance, digestive enzyme activity, inflammatory genes expression and intestine histology of silver sillago, Sillago sihama (Forsskål 1775), by replacing fish meal (FM) with low‐gossypol cottonseed meal (LCSM). Five isonitrogenous and isolipidic diets were formulated, including R0 group (control, containing 550.0 g/kg FM), R16 group (88.5 g/kg LCSM and 461.5 g/kg FM), R32 group (177.0 g/kg LCSM and 373.0 g/kg FM), R48 group (265.5 g/kg LCSM and 284.5 g/kg FM) and R64 group (354.0 g/kg LCSM and 196.0 g/kg FM). Fish fed R0 and R16 groups had a significantly higher weight gain rate (WGR) and specific growth rate (SGR) than R48 and R64 groups (p < .05). In contrast to whole‐body crude protein, whole‐body moisture increased with the FM level of substitution (p < .05). With the increased amount of LCSM in the diet, the activity of intestinal amylase (AMS) increased significantly (p < .05), and intestinal trypsin (TRP) decreased (p < .05). Dietary LCSM substitution upregulated the expression of intestinal tumour necrosis factor‐α (TNF‐α), the nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB), and interleukin one beta (IL‐1β), but downregulated tight junction proteins ZO‐1(ZO‐1), transforming growth factor beta‐3 (TGF‐β3) and interleukin 10 (IL‐10) expression. Histological analysis revealed progressive morphological damage to the mid‐intestine with higher levels of FM replacement. These results showed that 88.5 g/kg (16%) of FM replaced by LCSM with amino acids (methionine and lysine) supplementation did not significantly reduce growth compared with FM‐based control.