黄海北部辽宁近岸海域鳀产卵场分布特征及其影响因素

为掌握黄海北部辽宁近岸海域鳀(Engraulis japonicus)产卵场的分布特征及其关键环境因子,基于2021年4—12月开展的产卵场综合调查获取的鳀样品及其鱼卵密度数据,运用Garrison重心分布法阐释鳀产卵洄游分布特征及其主产卵期;通过基于Tweedie分布的广义可加模型(generalized additive model, GAM)的构建,分析主产卵期内鳀卵密度与同步获取的海水表层温度(SST)、海水表层盐度(SSS)、海水表层叶绿素浓度(Chla)、浮游动物丰度(Fd)、浮游植物丰度(Fz)和深度(Depth)等6个环境因子,以及时间(月份,Month)和空间(经纬度、Lon和Lat)因子之间关系,并识别主控因子。结果显示,海域内鳀产卵期较长,由4月持续至11月,5—8月为主产卵期,其中,5—6月为产卵盛期。鳀产卵场规模和位置时空变化明显,时空因子与鳀卵密度分布呈密切非线性相关(累积偏差解释率为48.1%),(SST, SSS) (18.7%)和Depth (5%)次之。鳀产卵期适温范围较广,产卵场分布表现出高温高盐(低温低盐)增效作用和高温低盐限制作用。产卵初期(4月),鳀产卵场规模和鱼卵密度均较低,产卵重心位于海洋岛东南侧深水区;盛期(5月底—6月初)在SST主导下,鳀产卵场规模和鱼卵密度均至年内最高值,核心产卵场位于石城岛–庄河河口一带海域;此后,随着辽南沿岸水系盐度的下降,高温低盐的抑制作用使SSS因素主导产卵鱼群避开沿岸海域,鳀产卵场迁移至外海深水区,7月后位于30~50 m等深线之间;9—10月鳀繁殖活动基本结束,10月鳀卵仅零星分布于调查海域,直至12月未有鳀卵采获。研究可为黄海北部辽宁近岸海域鳀产卵场研究及鳀资源合理开发利用提供参考依据。     

怎样正确购买受体牛

胚胎移植成功与否受体牛选择占有举足轻重的作用,下面谈谈怎样正确购买和选择受体牛。1品种受体牛品种的选择是做胚胎移植时应该首先考虑的问题。本地品种做受体会出现下列问题:受体牛体格小难产率高;由于都是役用牛产奶量很低,所产的牛乳不够犊牛吃;如是杂交牛,生殖器官发育往     

组蛋白在基因调控中的作用

组蛋白曾一度只被看成是细胞核ＤＮＡ结构的组成成分，是转录的通用抑制分子。最近研究表明，这类蛋白质是基因调节过程中活跃的参与者，不仅抑制又能促进许多基因的活化。     

Exploring polymorphisms and their effects on reproductive traits of the INHA and INHβA genes in three goat breeds

In this study, we report the analysis of INHA and INHβA gene polymorphisms in 786 goats of three breeds: Xinong Saanen (SN), Guanzhong (GZ) and Boer (BG). We identified three new allelic variants: P1–C80G and/126G (GenBank accession no. HQ202573) in the three goat breeds and P2–C936T (GenBank accession no. HQ202572) in SN and GZ goat breeds. At P1 locus, AA, AB and BB genotypes were found in the three goat breeds. At P2 locus, CC and CT genotypes were found in SN and GZ goat breeds. After comparing genotype distribution within the three goat breeds, BG had conspicuous differences from SN and GZ (P < 0.001) at P2 locus. The SNP locus was in Hardy–Weinberg disequilibrium at P1 locus in the three goat breeds (P < 0.05). At P2 locus, the SNP locus was in Hardy–Weinberg disequilibrium in SN and GZ goat breeds (P < 0.05). Association of polymorphisms with litter size was done at P1 locus in the three goat breeds. The result showed that AA genotype had remarkable litter size at P1 locus in the three goat breeds (P < 0.05). Therefore, these results suggest that INHA gene is a strong candidate gene that affects litter size in goats.     

盐渍地区草坪草品种及其混播组合筛选的研究

对 11种草坪草室内发芽试验表明 :盐浓度 0 %～ 1.6 %NaCl胁迫下相对发芽率均随盐浓度升高而下降 ,呈线性回归关系。在北方盐渍地上 0～ 2 0cm土层全盐含量不超过 1.0 %时 ,混播优于单播。表现较好的混播是多年生黑麦草 +碱茅 +草地早熟禾或匍匐翦股颖。其中多年生黑麦草发芽快、幼苗生长迅速 ,很快覆盖地面 ,有利于其他种子的萌发 ,称为保护种。碱茅幼苗期及成株后耐盐性均较强 ,但苗期生长慢 ,适宜与多年生黑麦草伴生。草地早熟禾和翦股颖品种中耐盐性较强的可作为主要草种     

规模化牛场粪污资源化技术研究及应用进展

现代规模化牛场发展迅速,为市民提供大量优良奶源和畜肉,但同时牛场产生粪便、污水等废弃物排泄量增加,大部分牛场不能规范化处理,粪污堆积在生产区域,不光对周围土壤、空气和水体造成污染,还影响牛场的正常养殖生产秩序,对生态环境危害严重,影响养牛业绿色可持续发展,因此牛粪的处理和资源化利用问题急需解决。为了稳定、无害的处理粪污,将规模化牛场粪污作资源化处理利用,不仅可以解决牛场粪污污染问题,还能实现粪污资源最大化利用,具有重要意义。本文分析了牛粪的营养成分以及规模化牛场粪污造成的环境污染问题,简述了粪污资源化利用的目的、原则和预期效果,介绍了牛粪资源化利用的现有途径和方式,其中主要包括能源化、基质化、饲料化、燃料化、肥料化、氧化塘发酵后再利用等方法,以期通过分析多种资源化处理技术,将其根据具体情况应用,或者多种技术搭配实施,避免单一技术存在的局限性,为不同养殖环境情况下的粪污处理提供参考,为现代化养牛业低碳可持续发展提供借鉴。在未来应继续加大规模化牛场粪污资源化利用力度,科学合理制定各地区养殖场的粪污处理规划和资源化利用模式,监测周围环境质量并作出有效控制,促进畜牧业健康发展,为畜牧业循环经济...     

动物基因定位的发展及其DNA标记技术研究进展

动物基因定位技术发展迅速,已在世界发达国家动物繁育领域得到了应用。本文介绍了动物基因定位技术发展的现状,以及动物基因定位标记的DNA技术,开创了动物基因定位和改良的新领域。研究动物的遗传结构和控制机制,揭示遗传结构和功能的内在联系。为动物定向培育的进一步发展提供参考。     

Effects of inoculants on the fermentation characteristics and in vitro digestibility of reed canary grass (Phalaris arundinacea L.) silage on the Qinghai‐Tibetan Plateau

To effectively use local available grass resources to cover the winter feed shortage on the Qinghai‐Tibetan Plateau, direct‐cut and wilted reed canary grass (RCG) silages were prepared by using a rolled‐bale system, and their ensiling characteristics and in vitro digestibility were studied. Silages were treated without (control) or with inoculants including LP (Lactobacillus plantarum), LPLB (L. plantarum, L. buchneri), and LPLBc (L. plantarum, L. buchneri, and cellulase), and were stored at ambient temperature (5.7–14.6°C) for 90 days. Compared with control, the inoculated silages increased (p < .05) lactic acid and acetic acid contents, and reduced (p < .05) final pH value and ammonia‐N ratio of total N. The highest WSC content (41.2 g/kg DM) occurred for LPLB‐inoculated silage, whereas LPLBc‐treated silage displayed the lowest contents of NDF (522.9 g/kg DM) and ADF (275.5 g/kg DM). In addition, LPLBc‐inoculated silage had the highest in vitro gas production (51.0 ml/g DM), in vitro DM digestibility (619.3 g/kg DM), and metabolic energy (9.6 kJ/kg DM). These results confirmed that treatments with inoculants at ensiling could improve silage fermentation and in vitro digestibility of RCG, and this could be a potential winter feed for animals on the Qinghai‐Tibetan Plateau.