Replacing Soybean Meal with Alternative Protein Sources in Diets for Pond‐raised Hybrid Catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus

The present study investigated the replacement of soybean meal with combinations of two or three alternative protein sources in diets for pond‐raised hybrid catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus. Alternative protein sources evaluated included cottonseed meal, distillers dried grains with solubles (DDGS), peanut meal, and porcine meat and bone meal (PMBM). Hybrid catfish fingerlings with a mean initial weight of 35 g/fish were stocked into 25 earthen ponds (0.04 ha) at a density of 14,826 fish/ha. Fish were fed once daily to apparent satiation for 166 d. No significant differences were observed for total diet fed, net yield, weight gain, survival, carcass yield, fillet yield, or fillet proximate composition among dietary treatments. Results show soybean meal may be completely replaced by combinations of cottonseed meal and one or two other alternative protein sources including DDGS, peanut meal, and PMBM in the diet without markedly affecting production and processing characteristics and fillet proximate composition of pond‐raised hybrid catfish. These alternative diets may be used during foodfish production when prices are favorable.     

Annual sex hormonal profiles, gonad development and age determination of the Mekong giant catfish (Pangasianodon gigas, Chevey)

Annual sex hormonal profiles, gonad development and age determination of 18 (13–14 kg body weight) and three (145–226 kg body weight) Mekong giant catfish (MGC) (Pangasianodon gigas, Chevey) reared in earthen ponds in Chiang Mai and from the Mekong River in Chiang Rai, Thailand, respectively, were investigated. The hormonal profiles were determined from blood samples of the fish by electrochemiluminescence immunoassay during May to August in 2000. The highest testosterone levels of 0.06 ng mL^?1 in both sexes and the highest oestradiol of 47.8 and 14.23 pg mL^?1 in females and males, respectively, were observed in May. The gonadosomatic index was found to be 0.07 for males and 0.38 for females from ponds in comparison with 2.27 for males and 8.29 for females from the Mekong River. Higher development stages of spermatocytes and oocytes of the cultured fish in May than in February and November were demonstrated. No mature germ cells were obtained from either the males or females, indicating no sexual maturity. The average age of fish was determined from the annual rings of the cross‐section of the pectoral fins by a stereomicroscope. The average age of fish in earthen pond determined from the annual ring was 8 years, which agreed with the actual culture records, while those from the Mekong River were 21 years. This information will be beneficial for the breeding programmes and conservation of the MGC.     

经营区边境伐区开设便道、拖拉机道的研究

对经营区边境伐区开设便道,还是开设手扶拖拉机道进行技术分析与经济分析,采用盈亏平衡分析法决策,并用实例论证其实用价值。     

Being exposed to low concentrations of pirimiphos-methyl and chlorfenapyr has detrimental effects on the mobility of Trogoderma granarium

BACKGROUND

Sublethal effects of insecticides may negatively affect several biological and behavioral traits of insects. The lethal effects of pirimiphos-methyl and chlorfenapyr have been previously showed on Trogoderma granarium, but little knowledge is available about their sublethal effects at low concentrations on both sexes. Herein, the sublethal effects of pirimiphos-methyl and chlorfenapyr on the mobility of T. granarium males and females were investigated.

RESULTS

Lethal concentration (LC) values of pirimiphos-methyl and chlorfenapyr were lower for T. granarium females than males. LC values on males were LC₁₀ = 0.000788 and 0.00139 mg active ingredient (a.i.) cm⁻², LC₃₀ = 0.00350 and 0.00535 mg a.i. cm⁻², and LC₅₀ = 0.00986 and 0.0136 mg a.i. cm⁻² for pirimiphos-methyl and chlorfenapyr respectively. LC on females were LC₁₀ = 0.000704 and 0.00110 mg a.i. cm⁻², LC₃₀ = 0.00323 and 0.00428 mg a.i. cm⁻², and LC₅₀ = 0.00925 and 0.0110 mg a.i. cm⁻² for pirimiphos-methyl and chlorfenapyr respectively. The walking duration of beetles exposed to LC₃₀ of pirimiphos-methyl was significantly lower than the individuals exposed to LC₁₀ and LC₃₀ of both insecticides and control ones. Pirimiphos-methyl LC₃₀-exposed males remained more time on their back (101.7 s) than females (46.9 s), while the latter stayed immobile longer than males (381.7 s versus 371.9 s). The highest speed was recorded for control beetles (14.17 mm s⁻¹ females vs. 12.44 mm s⁻¹ males), while the lowest speed was observed in pirimiphos-methyl LC₃₀-treated males (8.36 mm s⁻¹) and females (9.66 mm s⁻¹).

CONCLUSIONS

Overall, males and females exposed to low concentrations of pirimiphos-methyl and chlorfenapyr showed reduced motility. This knowledge can be exploited further to unlock behavioral effects of insecticides for effective pest management programs in warehouses. © 2023 Society of Chemical Industry.     

稻麦联合收获开沟埋草多功能一体机行走及脱粒性能改进

针对自行研制的稻麦联合收获开沟埋草多功能一体机所存在的行走直线稳定性差、脱粒质量较低等问题。依据横向轴流式滚筒对稻麦秸秆的传递导流作用和二次复脱的原则,通过增设辅助滚筒的方法既改变出草口位置使开沟总成中移,消除整机偏向力,又延长秸秆在滚筒内的作用时间,提高谷物脱粒质量。其中:辅助滚筒总长为855 mm,导流角为18°,滚筒直径为452 mm,转速为1 350 r/min。性能测试表明:改进后自研一体机在0.27、0.58、0.85 m/s 3种不同工况下行走偏移度分别降低了93.9%、94.4%、93.3%,行走直线稳定性显著提高;小麦和水稻总损失率分别降低20.9%和11.8%,含杂率分别降低45.7%和21.4%。尽管水稻破碎率增加了7.4%,但脱粒的综合质量有较大提高。该研究增进了多功能一体机的适用性,为稻麦秸秆机械化集沟还田提供了参考。     

五味子园除草机的研制与应用

设计、制造一种五味子园除草机,并进行田间试验应用与效益分析。该除草机采用手扶拖拉机为配套动力,利用最终传动齿轮,通过除草机的传动箱带动除草轮在地面上滑转来剖切土壤,达到除草和疏松土壤的目的;同时配置培土犁,一次可完成除草、深松、培土复式作业。应用试验表明,该除草机各项技术指标均达到设计标准,能够满足农艺要求。     

大型机具行走带双轴地轮设计

针对大型农机具地轮动力不足、分布位置及结构形式不合理等问题,设计开发了行走带双轴地轮机构。该机构主要由深度控制及轴间差速机构组成。将地轮机构分两组布置于拖拉机行走带上,单组采用双轴简支、轴间差速的设计方案,双侧同步液压缸控制耕深。研究结果表明:该地轮具有结构紧凑、播种深度调整方便、仿形性好和驱动力大等特点。     

摄食水平对黄颡鱼氮和能量收支的影响

在25℃、自然光照条件下,测定黄颡鱼在摄食水平为1/3饱食、2/3饱食和饱食时的氮和能量收支.结果显示,摄食水平对黄颡鱼的氮收支和能量收支均有显著影响,随着摄食水平的提高,生长氮和生长能的比例显著提高,排泄氮、粪氮和代谢能的比例显著下降,但在饱食2/3和饱食水平时,生长氮、生长能、排泄氮和代谢能比例差异都不显著.     

斑点叉尾鮰对3种致病菌灭活菌苗的免疫应答

将经福尔马林灭活的柱状嗜纤维菌(Cytophaga columnaris)、嗜水气单胞菌(Aeromonas hydrophi-la)和叉尾鮰爱德华菌(Edwardsiella ictaluri)作为免疫原,分别接种斑点叉尾鮰(Ictalurus punctatusRafinsque)后,通过测定受免鱼的交叉凝集抗体效价、头肾和血液中吞噬细胞的吞噬活性及用A.hydrophila活菌攻毒的方法,探讨了斑点叉尾鮰对3种灭活菌苗的免疫应答状况。试验结果表明,对斑点叉尾鮰经腹腔注射接种3种灭活菌苗能刺激受免鱼产生较强的免疫应答,受免鱼产生了对3种致病菌的特异性凝集抗体和交叉凝集抗体,与未接种菌苗的对照鱼相比,受免鱼头肾和血液中吞噬细胞的吞噬活性明显上升,活菌攻毒的结果也证明了受免斑点叉尾鮰对C.columnaris,A.hydrophila和E.ictaluri产生了不同程度的相对免疫保护率(RPS)。     

鲶人工繁殖关键技术的研究

本是１９９５～１９９７年鲶人工繁殖关键技术研究的总结,论述了♀♂鲶的鉴别指标,产卵习性与♀♂亲鱼分池培育,催情产卵和孵化,产卵行为与♀♂亲鱼个体大小搭配等鲶人工繁殖的系列关键技术问题,本试验共催情鲶２１３６组,获卵４５３７万粒,相对产卵数２．００～２．３３万粒／ｋｇ,下塘鲶苗１８８７．３９万尾,平均产卵率８１．１２％,受精率９４．９６％,孵率率８５．４％,下塘率４１．６％。