非洲猪瘟疫情下猪育种面临的困境与对策

自2018年8月以来暴发的非洲猪瘟疫情给我国猪育种和生猪生产带来了极大的困扰，育种体系遭受重创。文章综述了非洲猪瘟对我国育种体系的影响、育种工作面临的困境与挑战以及非洲猪瘟形势下猪育种的对策。     

围产期奶牛血钙影响因素及其与生产性能关系分析

本试验旨在探究围产期奶牛血钙浓度影响因素及其与生产性能的关系。于2018年7月20日—8月15日对北京地区36头围产期健康荷斯坦牛的血钙浓度进行测定,收集该牛场奶牛生产性能测定(DHI)报告,利用固定效应模型分析不同胎次、体况评分(BCS)、健康状况及血钙浓度变异度对血钙浓度的影响。结果表明:血钙浓度与产后天数存在显著的正向相关关系;经产牛的血钙浓度(1.40 mmol/L)极显著高于初产牛(1.31 mmol/L);不同BCS分组奶牛血钙浓度差异不显著;健康组的血钙浓度(1.41 mmol/L)显著高于患病组(1.30 mmol/L);血钙浓度变异度的大小影响奶牛的产奶量,初产奶牛低变异度组的产奶量(16.70 kg/d)显著高于中变异度组(9.75 kg/d)和高变异度组(5.63 kg/d)。本研究进一步揭示了围产期荷斯坦牛血钙浓度的变化规律以及其影响因素,为预防奶牛产后低血钙症的发生以及制定提高奶牛生产性能的饲养管理策略提供参考。     

野生稻种质在水稻抗病育种上的研究及应用进展

野生稻是一个重要的基因资源库,包含了水稻各种病害的抗性基因。本文综述了野生稻丰富的抗性资源及其基因的挖掘,以及在水稻育种上的利用研究进展,并对目前存在的突出问题,提出了野生稻种质资源抗病育种的发展建议。     

糯玉米新品种河糯612的选育及高产栽培技术

河糯612是以自交系 HN601作为父本，与自主选择自交系 HN16作为母本，经杂交选育而成的糯玉米杂交种，于2018年5月30日通过广西壮族自治区农作物品种审定委员会审定。河糯612幼苗长势旺盛、整齐，植株穗位、株高较为整齐，果穗均匀、穗长较长，结实好，行排列整齐，行间紧致，出籽率比较高，色泽好。可在广西全区种植。     

Pre-breeding for resistance to Verticillium wilt in olive: Fishing in the wild relative gene pool

This study aimed to identify new sources of resistance to Verticillium wilt in olive. We evaluated various types of genotypes: wild olive trees (Olea europaea subsp. europaea var. sylvestris), genotypes belonging to related subspecie (Olea europaea subsp. guanchica) and genotypes coming from crosses between Picual cultivar and wild olive trees. Fifty-six genotypes were inoculated by dipping roots and then screened under controlled conditions to test their resistance to a highly virulent Defoliating isolate of Verticillium dahliae. Picual (susceptible) and Frantoio (resistant) were control cultivars. Wide variability and significant differences were obtained in the evaluated disease parameters. The Relative Susceptibility Index (RSI), summarizing the disease parameters, was used for final classification of genotypes. Thirteen genotypes were categorized as resistant: eight wild olives from different locations, two genotypes belonging to subsp. guanchica populations from Canary Islands and three genotypes obtained from one of the crosses Picual x wild. The identification of high levels of resistance to V. dahliae among wild olive genotypes may be helpful for the management of this disease. The resistant genotypes could be used as rootstocks for susceptible olive cultivars or parents in future breeding programs.     

推进种养结合的制约因素及政策建议

随着粮食增产的迫切需求和化肥工业的快速发展,我国种植业与养殖业养分物质循环断裂,推进种养结合成为实现农业绿色发展重要途径。但目前,我国从农户层面以及区域层面都存在着种植与养殖之间的纽带断裂,造成了农业资源利用的错位,也产生了资源环境双重压力。推进种养结合的堵点主要表现在养殖场责任尚未压实、有机肥施用不便利、堆肥质量标准缺失、社会化服务体系不完善等多方面。本文结合对国内和国际上推进种养结合的典型做法的分析,在强化提升国家粮食安全保障能力的大背景下,从优化种养布局规划、压实养殖主体责任、强化科技支撑、培育社会化服务组织等方面提出了当前构建全新的种养循环体系的建议。     

2013年国外家兔遗传育种研究进展

我国是养兔大国，但家兔遗传育种基础研究薄弱。文章对2013年国外家兔遗传育种最新研究进展进行综述，以期为国内家兔育种者提供参考。     

过氧化氢和甲醛对SPF级大鼠和小鼠繁殖室消毒效果观察

目的比较观察过氧化氢和甲醛对SPF级大鼠和小鼠繁殖室内表面、台面以及空气的消毒效果,选择消毒效果良好的消毒剂。方法采用空气落下菌检测法和表面细菌拭子检测法,对过氧化氢和甲醛熏蒸SPF级大鼠和小鼠繁殖室的消毒效果进行检测观察。结果SPF级大鼠和小鼠繁殖室分别经过氧化氢和甲醛熏蒸消毒后,进行空气落下菌的检测,过氧化氢和甲醛对大鼠繁殖室和小鼠繁殖室空气的杀菌率分别为100%、97.5%和100%、100%;将墙壁、地面和笼架表面的菌落数进行检测,过氧化氢和甲醛对大鼠繁殖室墙壁、地面和笼架的杀菌率分别为100%、99%、100%和95%、100%、99%,对小鼠繁殖室墙壁、地面和笼架的杀菌率均为100%。结论过氧化氢蒸汽消毒是比较理想的消毒方法,很好地控制了SPF级大鼠和小鼠繁殖室环境微生物,安全性高且消毒效果明显。     

木棉雄蕊特征与其繁殖策略的关系分析

采用野外观察和实验室检测方法,对云南省个旧市冷墩村的木棉花部结构、雄蕊特征、花粉活性进行研究。结果表明,自然种群中花部形态特征具有一定变异性,3层雄蕊变异系数大小关系显著。在湿度为60%、温度为35℃时花粉活性最强。研究发现,木棉雄蕊长短变化可能有利于不同传粉生物传粉效率提高和增强适应性;木棉高层雄蕊花药个体大、花粉数量多、活性高,适应干热河谷传粉繁殖条件;温度较低时,底层花药花粉活力相对较高,可为逆境环境下木棉高层花药受损后提供后备花粉源。文章就木棉花部形态与繁殖关系、木棉形态及花粉活力对繁殖的影响进行讨论。     

Associations between postpartum diseases and milk yield and changes in body condition between drying off and parturition of dairy cows in Argentina

ABSTRACT

Aims: To assess the change in body condition score (BCS) during the early and late dry periods and its association with postpartum diseases and milk yield in grazing dairy cows from central Argentina.

Methods: BCS assessments during the dry period, and cow health and milk production records up to 90 days in milk (DIM), were collated for cows from 28 farms at monthly visits between 2007 and 2008. Cows were categorised into four groups; those in Group 1 (n=7,067) maintained or gained BCS during the early and late dry periods; Group 2 (n=2,615) maintained or gained BCS during the early dry period and lost BCS during the late dry period; Group 3 (n=1,989) lost BCS during the early dry period and maintained or gained BCS during the late dry period; and Group 4 (n=5,144) lost BCS during the early and late dry periods.

Results: Cows in Group 1 had reduced odds of having retained fetal membranes (RFM), metritis, and clinical mastitis up to 90 DIM than cows in Group 2 (p<0.001), but the odds of disease were similar to cows in Group 3. The odds of having RFM or clinical mastitis tended to be lower in cows in Group 1 than cows in Group 4 (p=0.08). The odds of cows being culled or dying during the first 90 DIM were lower for cows in Group 1 than for those in Groups 2, 3, and 4 (p≤0.05). Mean accumulated milk yield up to 90 DIM was higher in cows in Group 1 than Group 2 and Group 4 (p<0.001), but was similar to that of cows in Group 3 (p=0.28).

Conclusions and clinical relevance: Cows that lost BCS during the late dry period had increased odds of being diagnosed with several postpartum diseases and had decreased milk yield compared to cows that maintained or gained BCS during the entire dry period. Loss of BCS during any stage of the dry period was also associated with increased incidence of culling or death during the first 90 DIM. These results should raise awareness among dairy cattle producers of the importance of properly managing cow body condition during the dry period, especially during the late dry period.