美系杜洛克种猪体尺、体重测定与体型评定研究

统计分析了2001年引进的新美系杜洛克种猪及繁殖后代在6月龄、12月龄、24月龄和36月龄四个阶段的体尺、体重数据，结合品种特征、体型外貌总结研究出杜洛克种猪的百分制评分及等级标准。     

137Cs示踪法在东北松嫩平原土壤侵蚀定量评价中的应用

根据不同退化程度草原和不同开垦年限农田土壤137Cs放射强度分析结果表明:与轻度退化草原相比,中度退化和重度退化中的137Cs放射强度分别下降了21%和52%。草原土壤开垦后,137Cs放射强度明显下降,开垦7年、15年、33年后,137Cs的放射强度分别只有轻度退化草原的37%、31%和26%。相关分析表明,伴随着土壤侵蚀的发生,土壤有机质含量、全N含量以及阳离子交换量下降。137Cs放射强度与土壤有机碳、土壤全N、交换性K和阳离子交换量呈极显著的正相关。     

Single step genomic evaluation for female fertility in Nordic Red dairy cattle

Joint Nordic (Denmark, Finland, Sweden) genetic evaluation of female fertility is currently based on the multiple trait multilactation animal model (BLUP). Here, single step genomic model (ssGBLUP) was applied for the Nordic Red dairy cattle fertility evaluation. The 11 traits comprised of nonreturn rate and days from first to last insemination in heifers and first three parities, and days from calving to first insemination in the first three parities. Traits had low heritabilities (0.015–0.04), but moderately high genetic correlations between the parities (0.60–0.88). Phenotypic data included 4,226,715 animals with records and pedigree 5,445,392 animals. Unknown parents were assigned into 332 phantom parent groups (PPG). In mixed model equations animals were associated with PPG effects through the pedigree or both the pedigree and genomic information. Genotype information of 46,914 SNPs was available for 33,969 animals in the pedigree. When PPG used pedigree information only, BLUP converged after 2,420 iterations whereas the ssGBLUP evaluation needed over ten thousand iterations. When the PPG effects were solved accounting both the pedigree and the genomic information, the ssGBLUP model converged after 2,406 iterations. Also, with the latter model breeding values by ssGBLUP and BLUP became more consistent and genetic trends followed each other well. Models were validated using forward prediction of the young bulls. Reliabilities and variance inflation of predicted genomic breeding values (values for parent averages in brackets) for the 11 traits ranged 0.22–0.31 (0.10–0.27) and 0.81–0.95 (0.83–1.06), respectively. The ssGBLUP model gave always higher validation reliabilities than BLUP, but largest increases were for the cow fertility traits.     

The use of ultrasonography in the reproductive evaluation of boars

The objective was to study the use of ultrasound as a complementary test in the breeding soundness evaluation in male pigs and study the pattern of echogenicity of the testicular parenchyma in boars of different racial groups. Twenty‐six adult boars from four different racial groups were used, 10 from the Piau breed (group 1), four from the commercial and finishing group (group 2), six Pietrain breed (group 3) and six from the Duroc breed (group 4). All animals were evaluated for breeding soundness evaluation and the ultrasound examination of the testicles. The groups of animals that were evaluated showed no difference in the main semen parameters that were evaluated, except for the sperm volume, concentration of the ejaculated sperm and the supravital staining; the lowest figures were for the animals from the Piau breed (group 1). In relation to the testicular biometrics, Duroc animals (group 4) had a greater scrotal width compared to the other groups. But when we assessed the intensity of pixels of the testicles, there was a difference between groups. The groups 2 (finishing animals), 3 (Pietrain) and 4 had no difference between themselves. Group 3 had greater pixel intensity in relation to group 1. Of the 26 animals studied, five showed an abnormality during ultrasound evaluation, like hydrocele, hyperechoic mass in the testicular parenchyma, cyst in the head of the epididymis and the presence of fluid in the head and tail of the epididymis. The various animal groups studied did not differ in the principal reproductive parameters evaluated, showing that despite the great variability of reproductive traits between breeds and within the same breed, the breeding soundness evaluation, the more complete it is, is essential for the selection of breeders and the ultrasonography of the reproductive system becomes an important addition in this examination.     

不同施氮量及栽培密度对烟叶质量的影响

设置了不同施氮量及栽培密度对烟叶质量的影响试验.结果表明:在一定范围内,随施氮量增加,烟株长势越好;随种植密度的增加,烟叶产值、产量越高.以施纯N6kg/667m2,移栽密度为110cm×56cm处理的初烤烟叶产值、产量、外观质量等效果最佳.     

中国农村合作经济组织发展研究述评

随着国内理论界对农村合作经济组织研究的逐步深入,成果斐然;但同时还存在一些不足,难以有效促进组织的发展。笔者从促进中国农村合作经济组织的发展的视角出发,筛选了国内核心刊物上20世纪90年代以来合作经济组织研究的新进展,对组织存在的必然性、运行机制、发展思路与模式等方面进行了综述,指出其对合作组织发展的重要启示和意义,并对研究进展进行了简要的评价。     

稻田入土生物质炭自然陈化过程理化特性变化规律

为探究生物质炭入土后其长期理化特性变化,以水稻秸秆生物质炭为试验材料,通过分析长期定位试验田中的入土生物质炭样品,探究了稻田土壤中生物质炭的理化特性变化规律。结果表明,入土生物质炭颗粒随时间推移经历持续性物理破碎,平均孔径显著降低,入土 11 年后,生物质炭比表面积从初始的 55.0 m²·g^-1增大到 259.0 m²·g^-1,氢与碳的摩尔比从最初的 0.423 提升至 0.568,不饱和度显著提升。入土生物质炭 C=O(1 600～1 630 cm^-1)和 C—O—C(1 080 cm^-1)的骨架振动强度和芳香族 C—H(790 cm^-1)的平面振动均增强,其含氧官能团的类型和含量呈现明显增加的趋势。与此同时,入土生物质炭的可热降解组分占比不断提高,热稳定性逐渐降低。研究表明,与实验室老化模拟试验结果明显不同,受诸多外力作用和环境因素的影响,稻田中入土生物质炭的理化特性发生了更显著的变化,稳定性随着时间的推移逐年降低。因此,为精准...     

MHC及其在动物遗传与育种方面的应用

主要组织相容性复合体(Major histocompatibility complex,MHC)不仅与移植排斥反应有关,而且还与动物的一些经济性状密切相关。文章主要阐述了MHC的结构、功能和遗传特性,并且介绍了MHC基因作为遗传标记在动物遗传与育种方面的应用。     

基于养分专家系统的西北旱地冬小麦推荐施肥效应研究

[目的]本研究调查了养分专家系统(Nutrient Expert,NE)推荐施肥在西北旱地冬小麦生产上的应用效果,以明确该方法在西北旱地小麦推荐施肥中的可行性.[方法]在陕西渭北旱塬两年共布置15个田间试验,所有试验均设置两个处理:养分专家系统推荐施肥(NE)和农户习惯施肥(FP).在小麦成熟期采集小麦样品和0—100...     

咸干蓝点马鲛品质特征与优势菌群分析

为了更好地了解传统咸干蓝点马鲛(Scomberomorus niphonius)(鲅鱼)的品质特征,以市售产品中感官品质较为突出的咸干鲅鱼作为研究对象,对其水分、含盐量、NaNO2含量、挥发性盐基氮(TVB-N)、硫代巴比妥酸值(TBARS)等理化指标进行了测定,并进一步对咸干鲅鱼中的优势菌进行了分离、纯化与鉴定。结果显示,咸干鲅鱼样品含水量为54.40%、含盐量为3.1%,属于半干低盐制品;NaNO2含量为5.07 mg/kg,符合相关食品安全标准的规定;TVB-N含量高达40.12 mg/100 g,说明发酵过程蛋白质降解程度较大;TBARS值为10.00 mg/kg,脂质氧化程度在感官可接受的范围内。咸干鲅鱼中的微生物以细菌为主,清酒乳杆菌(Lactobacillus sakei)、产气肠杆菌(Enterobacter aerogenes)、长赖氨酸芽孢杆菌(Lysinibacillus macrolides)和香坊肠杆菌(Enterobacter xiangfangensis)为优势菌。其中,清酒乳杆菌具有发酵菌的典型特征,可能在咸干鲅鱼发酵过程中起主要作用。