Growth and physiological responses of growing pigs to wheat–corn distillers dried grains with solubles

Gaining a detailed knowledge on the impact of a feedstuff on pig growth and physiological responses is critical for its effective utilization. Thus, the purpose of this study was to investigate the effect of distillers dried grains with solubles derived from co‐fermentation of wheat and corn (wcDDGS) on performance, carcass and visceral organ weights, whole‐body O₂ consumption and heat production (HP) in growing barrows. The experimental diets were as follows: corn–soybean meal diet (Control), Control + 15% wcDDGS and Control + 30% wcDDGS. In Exp. 1, 48 pair‐housed pigs of average BW 18.6 ± 1.5 kg (mean ± SD) were allotted to the 3 diets (n = 8). Pigs had free access to water and feed for a 28‐day period during which ADG and ADFI were calculated weekly. Thereafter, 1 pig/pen was killed to measure carcass and visceral organ weights. Overall, wcDDGS linearly decreased (p < 0.05) ADFI and ADG but had no effect on G:F (p > 0.10). The ADFI was 1.55, 1.45 and 1.36 kg/day for diets containing 0, 15 and 30% wcDDGS respectively; corresponding values for ADG were 0.79, 0.75 and 0.67 kg/day respectively. A linear decline (p = 0.01) in eviscerated hot carcass weight was observed as dietary wcDDGS increased. In Exp. 2, 18 pigs of average BW 20.4 ± 2.4 kg (mean ± SD) were individually housed in metabolism crates and fed the 3 diets (n = 6) at 550 kcal ME kg BW^?0.60day for a 16‐day period followed by measurement of O₂ consumption using an indirect calorimeter. Diet had no effect (p > 0.10) on whole‐body O₂ consumption and HP. In conclusion, increasing wcDDGS content in growing pig diets linearly reduced ADFI, ADG and eviscerated hot carcass weight but had no effect on G:F, visceral organ weights or HP.     

鱼鳞坑开沟双犁体翻转机构研究设计

双犁体翻转机构是对已有的发明专利机型即鱼鳞坑开沟犁装置的进一步优化设计,解决了在单犁体鱼鳞坑开沟犁返程时因开沟翻土方向不在坡下而是在开出的沟上面的作业问题。新研制翻转式鱼鳞坑开沟工作结构装置,应用机械、液压、电控装置实现了不同土壤类型的鱼鳞坑开沟间距式作业,生产效率高,性能可靠,市场前景广阔。     

木耳属4个野生菌株的培养特性研究

通过研究不同营养和环境条件对木耳属4个主要种类的野生菌株生长速率和生长势等培养特性的影响,明确了黑木耳、毛木耳、皱木耳、紫木耳菌丝生长的最适温度范围以及最佳碳源和氮源。     

Fast growth, protein turnover and costs of protein metabolism in yolk-sac larvae of the African catfish (Clarias gariepinus)

In fish larvae the costs of rapid growth may be accommodated by a decrease in the rate of protein turnover or by a reduction in the costs of protein synthesis. Protein growth, synthesis and degradation were measured in yolk-sac larvae of Clarias gariepinus and the costs of protein synthesis and protein growth were estimated. Growth rates were over 100% protein weight day^-1. Protein synthesis retention efficiency (retained protein per unit of synthesis) was estimated to be 69.6%, a value comparable to that of larger fish. The larvae used 43% of their oxygen consumption for protein synthesis. Nevertheless, protein synthesis costs were close to theoretical minima. Therefore, the high growth rates of catfish yolk-sac larvae seem to be possible through minimisation of the costs of protein synthesis. These low costs are associated with high rates of protein synthesis (138%protein weight day^-1), and elevated RNA concentrations (107 µg RNA mg^-1protein), which together suggest very high RNA efficiencies (12.9 g protein synthesized g^-1RNA day^-1).     

Effects of the protein/carbohydrate ratio of extruded diets on protein synthesis, protein growth and body composition in juvenile brown trout (Salmo trutta)

High levels of protein in fish feeds result in higher costs and nitrogen waste. Therefore, studies focused on protein substitution by alternative energy sources are necessary. Here we examine whether the protein:carbohydrate ratio in extruded diets affects protein-turnover parameters and the main tissue components in brown trout. Juvenile fish were adapted to two extruded diets: one higher in protein and lower in carbohydrate, C: 45/28 and the other higher in carbohydrate and lower in protein, HC: 37/40. Gross energy was 19 MJ kg⁻¹ DM in both diets. Protein and lipid digestibility were high and similar in both groups (≈90%), whereas total and carbohydrate digestibility and digestible energy were lower in the HC-fed group than in the C-fed group. Consequently, when fish were adapted to the diets, plasma levels of glucose and insulin differed between diets. HC-group presented higher plasma glucose levels and lower plasma insulin levels than C-group. Protein synthesis rates in white muscle, liver and whole body did not differ significantly between diets. In contrast, protein accretion rate of white muscle and whole body were significantly lower in the HC group, indicating an increase of protein degradation in these tissues and a decrease of synthesis retention efficiency. In spite of the daily protein intake of HC group was lower than C-group, the anabolic stimulation efficiency was increased by 34% in HC group. Protein and lipid contents in white muscle and liver were stable throughout the experiment. No hepatomegalia or increased fat deposition was observed in fish fed HC. Differences in specific growth rates (C: 0.88%; HC: 0.77%) were associated more with the lower protein consumption rate and the lower level of digestible energy in fish fed HC than with the higher dietary carbohydrate content of the diet.     

江苏省水稻生产的碳排放结构特征和影响因素研究——基于农户生产投入和规模的视角

基于对江苏省水稻生产农户的实地调研,运用投入产出法和生命周期法,对水稻生产的碳排放进行探究,并借助影响因素回归模型,探讨影响农户水稻生产碳排放的主要因素.结果表明：①江苏省农户生产1 hm2水稻的碳排放约为5 110.92 kgCe,从水稻碳排放结构特征来看,水稻生产中甲烷排放的比重较大,包括农用能源（煤炭、柴油、电力）及工业投入品（化肥、农药等）的全生命周期碳排放是水稻温室气体重要的来源;②家庭劳动力数量的增加并不会减少水稻单位产量的碳排放;③种植规模对水稻单位产量碳排放的影响显著为负,且种植规模效益地区差异明显.     

《土壤肥料学》教学过程中固碳思想的融入与加强探讨

介绍了固碳思想产生的背景,在此基础上提出《土壤肥料学》教学过程中固碳思想融入与加强的必要性,并从提高教师专业素质,优化课程教学内容,丰富课程教学方法,注重实践能力培养等方面探讨了实现途径.     

旅游交通能源消耗与碳排放研究

旅游业作为世界上最大的产业部门,其能源消耗和碳排放已经引起关注,其中旅游交通作为旅游业能源消耗和碳排放最主要的部门,许多学者对其进行了研究.科学全面地分析旅游交通能源消耗和碳排放有助于推动旅游交通的可持续发展,进而促进旅游业更健康地发展.分析了当前旅游交通能耗和碳排放的研究方法,然后从旅游交通能源消耗和碳排放的测度、影响因素、对环境的影响和响应对策等4个方面,综述了其主要的研究内容,最后对中国旅游交通能源消耗和碳排放的研究提出了建议.     

长白山8种林型土壤有机碳和全氮的质量分数及垂直分布特征1）

基于样地调查和室内分析,比较研究了长白山地区典型的8种森林类型土壤有机碳和全氮的质量分数、碳氮比、碳密度和氮密度的分布特征。结果表明,8种林型土壤有机碳和全氮的质量分数变化范围分别是36．99～70．33、3．14～6．04 g· kg－1,有机碳、全氮质量分数最大的林型均是阔叶混交天然林。红松天然林土壤C ／N值最大为15．56,其它C ／N值变化范围为10．55～12．19。在土壤垂直剖面上,随着土层深度的增加,土壤的有机碳、全氮质量分数随之递减,土壤密度随之递增。8种林型土壤碳密度是杨树天然林最大,为22．13 kg· m－2,氮密度是落叶松人工林最大,为1．97 kg· m－2;针阔混交人工林的碳密度和氮密度均为最小,分别是12．37、1．11 kg· m－2。