Subclinical ketosis in dairy cows: prevalence and risk factors in grazing production system

The purpose of this study was to estimate the prevalence of Subclinical ketosis (SCK) between 4 and 19 days in milk (DIM) in a grazing production system and investigate the importance of potential risk factors for SCK. This cross‐sectional study was conducted in dairy cows (n = 107), which had more of two parities. The concentration of β‐hydroxybutyric (BHB) in blood was quantified through a hand‐held meter. Potential risk factors evaluated were calving interval (CI), milk yield in previous lactation, metritis, dystocia, calf sex (male), parity (≤3 vs. ≥4) and pre‐partum body condition score (BCS ≤ 3.5 vs. ≥3.75). Prevalence of SCK was 10.3% (95% CI 4.7–15) between 4 and 19 DIM. Risk factors identified were the occurrence of both metritis and pre‐partum BCS ≥ 3.75. Cows with metritis had 4.9 (95% CI 1.17–20.98) times more risk of developing SCK than cows without metritis. And the cows with pre‐partum BCS ≥ 3.75 had 5.25 (95% CI 1.32–21.11) times more risk of developing SCK than cows with pre‐partum BCS ≤ 3.5. Metritis could induce a lower feed intake and promote the development of SCK. High pre‐partum BCS could induce a greater mobilization of body reserves altering liver function and aggravating post‐partum NEB. The results are indicative of the expected prevalence of SCK in grazing production system. Factors associated could help to identify cattle at risk of SCK and improve the management of strategies to limit the effects.     

Interactions between ice storage time, collagen composition, gaping and textural properties in farmed salmon muscle harvested at different times of the year

Atlantic salmon were sampled in June, September and February of the consecutive year and were stored on ice for up to 14 days in order to test the effect of harvest time and subsequent ice storage on meat quality. Texture and gaping frequency were analysed and were related to colour, protein degradation, collagen solubility, collagen types and final pH as well as lipid oxidation in the fillets to test possible interactions between harvest time and quality degradation during storage. In February, the connective tissue contained more soluble collagen and less insoluble collagen, as well as more of both types I and V collagen, than in the samples collected in June. During ice storage, fish became softer with a concomitant increase in the number of fish displaying very high gaping. pH increased during ice storage and fillet colour became lighter and redder, while yellowness changed in the fattier fillets upon ice storage. Ice storage resulted in changes in pepsin-soluble collagen (PSC) depending on harvest time as did both types I and V collagen. The softer the fish, the higher the gaping score and the more insoluble collagen, the less gaping occurred.     

复合汞膜阳极溶出法检测树叶上的附着铅

[目的]快速、简便测定树叶上的附着铅含量。[方法]以新型铕离子掺杂普鲁士蓝复合汞膜电极为工作电极,采用差示脉冲阳极溶出法,测定兰州市3个地点的城区绿化白蜡树叶上附着铅含量,并分析树叶上附着铅的主要污染来源。[结果]在介质0.01 mol/LHNO3、富集电位-1.000 V、富集时间60 s条件下,Pb2+的溶出峰电流与其浓度在2.4~120.0μg/L范围内存在良好的线性关系,检出限为0.2μg/L,RSD为1.35%。树叶上附着铅含量与邻近交通要道的车流量之间有一定的正相关性,表明汽车尾气是兰州市绿化白蜡树叶上附着铅的重要来源。[结论]复合汞膜阳极溶出法检测树叶上附着铅含量具有较高的准确度和较好的精密度,而且操作简便、快速,测定干扰小。     

大麻籽粕营养成分研究

 为了开发利用大麻籽粕，探讨其作为蛋白质饲料的可能性和可行性，首次按照国标方法对其进行了化学成分和氨基酸成分测定，计算了氨基酸化学分数。结果：大麻籽粕的粗蛋白质、粗脂肪、粗纤维、粗灰分分别为35.2%,0.5%,24.4%和8.7%，富含精氨酸、甘氨酸、丝氨酸和亮氨酸，蛋氨酸含量较低，蛋氨酸、胱氨酸和赖氨酸分别是大麻籽粕的第一、第二和第三限制性氨基酸，表明大麻籽粕可作为蛋白质饲料资源部分替代豆粕，但要在大麻籽的脱壳、提油工艺上注意提高粗脂肪含量、降低粗纤维含量，并注意氨基酸的平衡。     

聚晶金刚石—硬质合金复合片木工刀具的研制及其分析

以金属钴(Co)为主要成分的粘结剂,在高温高压下成功地将金刚石微粉与YG15硬质合金合成为聚晶金刚石—硬质合金复合片的超硬材料。经机械性能测试表明:当金刚石含量在85％左右时,聚晶复合片的抗弯强度较理想,适宜作木工刀具。同时,采用HL315硬钎焊解决了与45号钢制刀体的焊接问题。其刃部采用电火花粗磨及陶瓷基金刚石砂轮精磨,满足了聚晶复合片刀头的设计要求。于同类硬质合金刀具相比,其耐用度高20多倍,加工刨花板的刀具损耗费约下降37％,加工的表面质量优良。     

PTFE基复合材料的土壤粘附与磨料磨损的研究

研究了Al₂O₃颗粒填充PTFE和PTFE+50％(wt)PPS基复合材料表面上水的润湿及土壤粘附和磨料磨损特性。加入适当含量和一定尺寸的Al₂O₃粒子可提高水的前进接触角θ_a并使减粘性能保持在较高水平。PTFE(+PPS)—Al₂O₃复合材料表面在憎水性和非光滑性方面与某些土壤动物体表有相似特性。适量Al₂O₃粒子的弥散可明显提高复合材料的耐磨料磨损性能,且PPS可进一步改进复合材料的耐磨性。     

Score System Study for Hand-Extended Noodle Quality Based on HMW-GS Index in Wheat Flour

Hand-extended noodle, a special kind of noodle, requires particular quality flour to make it. High molecular weight glutenin subunits (HMW-GS) in wheat are important protein subunits, which affect flour quality. To improve breeding and selection efficiency of wheat varieties which are used in making hand-extended noodle, 100 spring wheat varieties were selected to study the importance of HMW-GS on noodle quality score indexes such as color, appearance, taste agreeability, toughness, stickiness, smoothness, taste, and total score, through methods of quantity theory and statistic evaluation. It was shown that the hand-extended noodle quality score of HMW-GS 1, 2*, N, 7, 7 8, 17 18, 22, 2 10, 2 11, 2 12, 5 10, and 10 was 5.40, 5.35, 0, 2.55, 2.56, 9.19, 0.05, 0.15, 1.49, 1.14, 10.00, and 5.14, respectively. The score system for hand-extended noodle quality based on HMW-GS index included eight multiple linear regression equations (R2 ＞ 0.98).Hence, using the HMW-GS composition, the eight hand-extended noodle quality indexes would be forecasted exactly.Results indicated that ideal subunit compositions of HMW-GS for this special usage were composition 1, 17 18, 5 10, or composition 2*, 17 18, 5 10. This standard could be used on variety selection in the early generation of breeding crosses. HMW-GS 2 10, 2 11, and 2 12 were the least desirable subunits for hand-extended noodle, which should be avoided in wheat variety selection aimed for hand-extended noodle flour use.     

玉米复合生物技术育种的研究

通过玉米花药培养、幼胚培养、化学药剂诱导孤雌生殖等复合生物技术结合常规育种，显著地提高了玉米组织培养和纯系的育成效率，从获得的135个纯系中筛选出14个有价值的突变系；30个高配合力系；配制出比对照增产10%～70%的组合85个，通过第二轮的花药培养和幼胚培养，分别获得了早熟、双穗、含糖量和含蛋白质高、配合力好的纯系V花91B，及抗倒、抗病的纯系e502GS等。经多次产量比较和两年的吉林省区域试验证明，V花91B×Mo17是一个适应性广、品质优良、抗寒性强的高产中早熟种，充分显示出玉米复合生物技术育种的优越性和存在的巨大潜力。     

Nutritional properties of nonrice crops in the Asian Rice Farming Systems Network

Six legume crops and three cereal crops in the Asian Rice Farming Systems Network were compared with IR58 brown rice in terms of dry matter, energy and protein yields per hectare. Sorghum was closest to brown rice in dry matter and energy yield but soybean had the highest protein yield. Peanut and soybean had higher crude fat than the other crops which accounted for their high energy content and yield among the legumes. Amino acid analysis showed cowpea, mungbean, pigeonpea, bushsitao, and soybean protein as limiting in sulfur amino acids (cysteine + methionine). Peanut protein was limiting in either lysine or tryptophan + threonine. Corn, sorghum and wheat proteins were limiting in lysine.