Responses of energy balance, physiology, and production for transition dairy cows fed with a low-energy prepartum diet during hot season

Twenty multiparous Chinese Holstein dairy cows calving in hot summer (S group), were compared with 20 similar control cows calving in cool autumn (C group). Diets were the same for both groups; prepartum diets had relatively low energy density. Average temperature–humidity index was 76.5 and 53.0 in summer and autumn, respectively. S group cows had significantly higher rectal temperatures (39.6 vs. 39.0 °C) and respiration rates (79.0 vs. 31.3 breaths/min) than C group, and consumed less feed (prepartum 8.0 vs. 12.3 kg/day, postpartum 16.3 vs. 21.2 kg/day). Calculated energy balance (EB) was ?7.98 vs. ?5.15 Mcal/day for S group prepartum and postpartum, respectively. In contrast, EB was 1.36 vs. ?2.03 Mcal/day for C group prepartum and postpartum, respectively. S group produced significantly less milk than C group by 15.4 % (5.2 kg/day) and 26.8 % (10.2 kg/d) for milk yield and energy-corrected milk, respectively. Percentages of milk fat (3.28 vs. 4.29 %), protein (3.08 vs. 3.33 %), and solids-not-fat (8.46 vs. 8.78 %) were significantly lower for S group. Milk urea nitrogen (19.54 vs. 13.31 mg/dL) was significantly higher in S group. Significantly lower feed efficiency was observed in S group (1.56 vs. 1.66). During the entire transition period, S group had significantly lower circulating glucose levels. S group had significantly higher levels of nonesterified fatty acids (NEFA) prepartum, but after 14 days in milk, NEFA was significantly lower. We conclude that increasing dietary energy density during transition period (especially prepartum) is necessary to minimize adverse effects of hot season.     

土壤质地、pH、有机质含量对镉存在形态的影响及其机理研究

在不同土壤质地、pH、有机质含量条件下,研究镉可交换态含量随时间的变化规律。结果表明,镉添加进土壤后,经过40～60 d可被土壤吸附和固定,并进入稳定状态。随着土壤粘粒占比的增大,土壤中镉可交换态含量显著降低;随着土壤pH的升高,土壤中镉可交换态含量总体呈降低趋势;随着有机质含量的增大,土壤中镉可交换态含量显著降低。     

Comparison of birth weight and umbilical and placental characteristics of cloned and artificial insemination-derived piglets

Somatic cell nuclear transfer (SCNT)-derived piglets have significantly higher stillbirth rate and postnatal mortality rate than artificial insemination (AI)-generated piglets. The question whether the low survival rate of SCNT piglets was related to birth weight, umbilical cord or placenta development was investigated. In this study, stillbirth rate, neonatal death rate, birth weight, umbilical cord status, placental parameters and placental gene expression patterns were compared between SCNT and AI piglets. Results showed that mortality rates at birth and during the neonatal stage of SCNT piglets were significantly higher than those of AI piglets. The incidence of abnormal umbilical cord in SCNT and SCNT-liveborn (SCNT-LB) piglets was significantly higher than in AI and AI-liveborn (AI-LB) piglets. Birth weight, placental weight, placental surface area and placental efficiency in SCNT and SCNT-LB piglets were significantly lower than those of AI and AI-LB piglets. Placental expression profiles of imprinting, angiopoiesis and nutrient transport-related genes were defective in SCNT-LB piglets compared with those in AI-LB piglets. Thus, the low survival rate of SCNT piglets may be associated with abnormal umbilical cord and placenta development. These characteristics may have resulted from aberrant expression of angiogenesis, nutrient transport, and imprinting-related genes in the placentas.     

不同种源文冠果1年生苗生长节律及性状相关性研究

为揭示文冠果苗期生长规律,以内蒙古赤峰市乌丹镇、坤都镇和天山镇及河南三门峡市陕县、河北张家口市蔚县的1年生实生苗为材料,观测分析不同种群苗木生长节律及变异。结果表明,种源间及种源内苗高、地径、主根长、根、茎生物量、根茎比均差异极显著,各性状都是陕县最高;苗高及地径生长均呈“慢-快-慢”的“S”型曲线,Logistic方程均达极显著拟合水平。苗高、地径速生期分别是31~47d和24~44d,速生期内日均生长量分别为0.42cm和0.06cm。陕县和蔚县种源速生期持续时间较长,各生长阶段净生长量也是陕县和蔚县较高。在北京开展文冠果造林可以重点考虑陕县和蔚县种源。     

外部条件对水稻镉吸收的影响研究进展

综述了土壤环境、土壤酸碱度和氧化还原电位、水稻根系分泌物、水分管理模式、温度对水稻镉吸收积累的影响,提出可以从农田镉生物修复技术的系统研究、降镉综合栽培技术研究、Cd胁迫对水稻生长发育、生理生化及品质的影响机理等方面开展进一步研究.     

水分管理对水稻镉吸收的影响

以晚稻品种玉针香和湘晚籼12号为供试材料,研究了3种水分灌溉方式(W1,长期淹水灌溉;W2,湿润灌溉;W3,阶段性湿润灌溉)对水稻糙米镉含量的影响。结果表明,在水稻生长的3个关键时期(分蘖期、灌浆期、成熟期),各部位镉含量、富集系数均以W3处理最高,W1处理最低;玉针香糙米镉含量W1处理分别比W2、W3处理低56.52%和66.67%,且W1处理与W3处理间存在显著差异;湘晚籼12号糙米镉含量W1处理分别比W2、W3处理低65.22%和52.94%,但各处理间差异不显著。可见,长期淹水灌溉是一项能够有效降低糙米镉含量的农艺措施。     

The residual level of isoprothiolane in paddy field surface water and its acute toxicity level on freshwater prawn,Macrobrachium lanchesteri

Paddy and Water Environment - The application of isoprothiolane in rice cultivation may give a risk to the aquatic ecosystem. The present study was undertaken to determine the level of...     

~(60)Coγ射线辐照扶芳藤枝条的表型变异研究

用60Coγ射线辐照扶芳藤枝条,扦插苗平均分枝数与辐照剂量呈极显著负相关。随着辐照剂量的增大,倾斜和匍匐生长的植株比例呈增加趋势。80 Gy处理有利于使植株的叶色在冬季仍保持绿色。V1代筛选出株高、平均节长、粗/长、叶形指数、叶面积以及枝条枯梢、分叉、叶序变化等性状的变异体。     

pH和曝气对水生植物去除富营养化水体中氮磷等物质的影响

利用植物浮床系统,通过室内静态模拟试验,研究了pH和曝气对水生植物净化富营养化水体影响。试验结果表明,不同pH处理6 d后,植物系统在pH8.9下对TN,CODMn,BOD5的去除效果最好,TP的去除效果在pH6.7下最好,Chla的去除效果在pH5.0下最好。然而,无植物系统中,TN,TP的去除效果在pH8.9下最好,BOD5的去除效果在pH6.7下最好,CODMn,Chla的去除效果在pH5.0下最好。有无植物系统中,曝气处理6 d后对TN影响很大,但去除率明显小于不曝气处理(P<0.001),除在豆瓣菜系统中,曝气还对CODMn去除产生一定的影响,但对TP和Chla的去除无影响。本试验结果还表明,植物修复系统和无植物系统中,不同pH处理下,水体中NH4-N,NO3-N,NO2-N的去除效果均在pH8.9处理下最好,且在pH8.9 曝气联合作用下水体中NH4-N,NO3-N,NO2-N的去除率也最高。