基于非稳态热探针法的稻谷导热系数的测定

根据传热理论,导出探针法测定稻谷导热系数的数学模型。通过测定探针的升温速率,由上述数学模型计算出不同含水率稻谷的导热系数。实验结果表明,在常温下,产于我国南方地区的短粒型稻谷的导热系数随含水率的增加而增大。回归分析表明,短粒型稻谷的导热系数与含水率之间为线性关系。     

减缓肉牛热应激最新研究进展

为了减少肉牛热应激对肉牛生产性能、生理生化指标、抗氧化能力、妊娠牛激素及免疫功能等方面产生的影响,笔者检索了国内外相关文献,从品种、中草药方剂和饲料添加剂、环境控制三方面归纳在肉牛抗应激能力的最新研究进展,为肉牛健康高效养殖提供参考。     

不同地区白颖苔草在热胁迫下的生理反应

通过光照培养箱模拟北京地区的高温高湿环境,将来源于黄骅、顺义、丰镇、乌海、海淀5个地区的白颖苔草(Carex rigescens)进行热胁迫21d,以胁迫第1d的数据作为对照,每隔4d对相对电导率、叶绿素含量、丙二醛(MDA)含量、脯氨酸(Pro)含量、保护性酶及可溶性蛋白7个生理指标进行分析比较.结果表明:随着热胁迫时间的延长,与对照相比各材料的过氧化物酶(POD)活性、MDA含量、Pro含量均显著上升之后下降,相对电导率显著增加,可溶性蛋白含量无明显变化,超氧化物歧化酶(SOD)活性及叶绿素含量变化趋势各不一致.通过隶属函数法综合分析可知,不同地区的白颖苔草耐热性高低顺序为:黄骅＞乌海＞丰镇＞海淀＞顺义.     

热应激对鸡新城疫疫苗免疫效果的影响

本试验利用伊莎蛋雏鸡,分别接种新城疫油乳剂灭活苗和Ｎ－７９弱毒苗,油乳剂灭活苗免疫的各试验组抗体滴度稍有下降,与对照组间无明显的差异;Ｎ－７９弱毒苗免疫的各试验组,高温处理２４小时的雏鸡,抗体滴度稍低于对照组,但无明显差异;而高温处理４８小时的各组,抗体滴度均显著低于对照组（ｐ＜０．０５）。     

Pollen grains of heat tolerant tomato cultivars retain higher carbohydrate concentration under heat stress conditions

Exposure to high temperatures (heat stress) causes reduced yield in tomatoes (Lycopersicon esculentum), mainly by affecting male gametophyte development. Two experiments were conducted where several tomato cultivars were grown under heat stress, in growth chambers (day/night temperatures of 31/25 °C) or in greenhouses (day/night temperatures of 32/26 °C), or under control (day/night temperatures of 28/22 °C) conditions. In heat-sensitive cultivars, heat stress caused a reduction in the number of pollen grains, impaired their viability and germinability, caused reduced fruit set and markedly reduced the numbers of seeds per fruit. In the heat-tolerant cultivars, however, the number and quality of pollen grains, the number of fruits and the number of seeds per fruit were less affected by high temperatures. In all the heat-sensitive cultivars, the heat-stress conditions caused a marked reduction in starch concentration in the developing pollen grains at 3 days before anthesis, and a parallel decrease in the total soluble sugar concentration in the mature pollen, whereas in the four heat-tolerant cultivars tested, starch accumulation at 3 days before anthesis and soluble sugar concentration at anthesis were not affected by heat stress. These results indicate that the carbohydrate content of developing and mature tomato pollen grains may be an important factor in determining pollen quality, and suggest that heat-tolerant cultivars have a mechanism for maintaining the appropriate carbohydrate content under heat stress.     

大赖草染色体对小麦农艺性状和抗病、耐热性的效应研究

【研究目的】明确大赖草染色体对小麦农艺性状、抗病性和耐热性的效应,为进一步利用大赖草优异基因提供理论依据。【方法】通过黄矮病、白粉病、条锈病人工接种或自然发病鉴定抗病性,以分期播种模拟高温胁迫环境,通过千粒重变化评价耐热性,收获后调查农艺性状、再生性,对小麦-大赖草二体附加系、代换系和亲本‘中国春’进行农艺性状效应鉴定。【结果】结果表明,10个异染色体系苗期对白粉病菌株E09均表现高感,温室成株期白粉病抗性好于对照普通小麦‘中国春’;对条锈病抗性表现均优于‘中国春’。大赖草H染色体有增加穗长、小穗数、提早抽穗期、增加黄矮病抗性的正向效应。大赖草H、A染色体具有增加耐热性的正向效应;大赖草J染色体对粒长、粒宽和粒厚均有正向效应。大赖草A、L染色体含有控制芒的基因,大赖草F具有再生性和复小穗基因,【结论】10份异染色体系中未发现含高抗小麦白粉病基因的大赖草染色体,大赖草附加系DALr#A、DALr#F、DALr#H、DALr#J可用于小麦农艺性状、抗黄矮病、条锈病和耐热性的改良。     

Apparent digestible protein,energy and amino acid availability of three plant proteins in Florida pompano,Trachinotus carolinus L. in seawater and low‐salinity water

Two experiments were conducted with Florida pompano, Trachinotus carolinus L. at 3 and 28 g L^?1 salinity to determine apparent crude protein digestibility (ACPD), energy digestibility (AED) and amino acid availability (AAAA) from soybean meal (SBM), soy protein isolate (SPI) and corn gluten meal (CGM). Mean AAAA was similar to ACPD. In fish adapted to 3 g L^?1 salinity, they were 81.2% and 81.9% (CGM), 93.6% and 92.2% (SBM), 93.8% and 93.1% (SPI) for AAAA and ACPD respectively. In fish adapted to 28 g L^?1, they were 84.5% and 83.4% (CGM), 86.5% and 87.1% (SBM), and 83.4% and 85.0% (SPI) for AAAA and ACPD respectively. The AED was highest for SPI and lowest for SBM and inversely related to carbohydrate. The ACPD, AED and AAAA of soy products appeared to be lower in high salinity, whereas CGM was unaffected. The data suggest that SBM, SPI and CGM should be further evaluated as partial fishmeal replacements in Florida pompano diets. Application of the generated coefficients can be used to develop well‐balanced, low‐cost diets for Florida pompano reared in low salinity or seawater.     

Evaluation of apparent digestibility coefficients of individual feed ingredients in spotted rose snapper Lutjanus guttatus (Steindachner, 1869)

Apparent digestibility coefficients (ADCs) for dry matter, crude protein, energy and essential amino acids for five commonly used feed ingredients were determined for juvenile spotted rose snapper Lutjanus guttatus (average body weight 90.6 g). ADCs were determined using the stripping technique to collect faeces after fish were fed a reference diet and test diets composed of 700 g kg^?1 reference diet and 300 g kg^?1 test ingredient. Chromic oxide (Cr₂O₃) was used as an inert indicator. Ingredients tested included sardine fishmeal (FM), canola meal (CM), tuna by‐products meal (TBM), poultry by‐product meal pet grade (PBM‐PG) and solvent‐extracted soybean meal (SBM). In general, all ingredients showed high digestibility values for all essential amino acids, although differences were detected among ingredients. ADC values for dry matter, protein and energy ranged 77.0–80.4%, 84.3–82.5% and 89–88.8%, respectively, for marine ingredient and land‐based animal protein sources, and 75.0–74.2%, 81.5–80.9% and 87.4–86.8%, respectively, for the plant‐based protein source. SBM, TBM and PBM‐PG should be further evaluated in feeding trials as partial FM replacements in rose snapper L. guttatus diets. Knowledge of ADC values for these ingredients will allow feed producers to develop nutritionally balanced, low‐cost feed formulations for this species.     

The Relationship Between Developmental Accumulation of Leaf Soluble Proteins and Vernalization Response of Wheat （Triticum aestivum L.em. Thell）

The relationship between vernalization requirement and quantitative and qualitative changes in total leaf soluble proteins were determined in one spring （cv. Kohdasht） and two winter （cvs. Sardari and Norstar） cultivars of wheat （Triticum aestivum L.） exposed to 4℃. Plants were sampled on days 2, 14, 21 and 35 of exposure to 4℃. The final leaf number （FLN） was determined throughout the vernalization periods （0, 7, 14, 24, and 35 d） at 4℃. The final leaf number decreased until days 24 and 35 in Sardari and Norstar eultivars, respectively, indicating the vernalization saturation at these times. No clear changes were detected in the final leaf number of Kohdash cultivar, verifying no vernalization requirement for this spring wheat cultivar. Comparing with control, clear cold-induced 2-fold increases in proteins quantity occurred after 48 h following the 4℃-treatment in the leaves of the both winter wheat cultivars but, such response was not detected in the spring cultivar. However, the electrophoretic protein patterns showed between-cultivar and between-temperature treatment differences. With increasing exposure time to 4℃, the winter cultivars tended to produce more HMW polypeptides than the spring cultivar. Similar proteins were induced in both Sardari and Norstar winter wheat cultivars, however, the long vernalization requirement in Norstar resulted in high level and longer duration of expression of cold-induced proteins compared to Sardari with a short vernalization requirement. These observations indicate that vernalization response regulates the expression of low temperature （LT） tolerance proteins and determines the duration of expression of LT- induced proteins.     

Partial replacement of soybean meal with Methylobacterium extorquens single‐cell protein in feeds for rainbow trout (Oncorhynchus mykiss Walbaum)

A feeding trial was conducted with juvenile rainbow trout (15–16 g initial weight) to assess the effects of including single‐cell protein (SCP) produced from Methylobacterium extorquens in trout feeds. Three isonitrogenous and isoenergetic diets were produced: a control diet and two experimental diets containing 5% or 10% bacterial protein meal replacing soybean meal. Triplicate tanks, each containing 35 fish, were fed each diet to apparent satiation in a constant‐temperature (15°C), flow‐through tank system for 12 weeks. No statistically significant differences in final fish weight or other fish growth parameters were observed. Similarly, feed efficiency parameters showed no significant differences among groups. Nutrient retention indices (protein, fat, energy) were relatively high and similar among fish in each dietary treatment group, as were whole body proximate compositions. Fish survival was high, with a small but statistically significant increase for the 10% SCP diet. Overall, results demonstrate that SCP from M. extorquens is a safe and effective alternative protein for rainbow trout diets at the low inclusion levels tested. Slightly lower weight gain in fish fed the 10% SCP diet was largely due to lower feed intake, suggesting that adding palatability‐enhancing ingredients to feeds may allow higher levels of M. extorquens SCP to be used without compromising fish growth.