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1.
本研究应用女母回归法、公畜内女母回归法、半同胞相关法和单元内半同胞相关法对内蒙古阿尔巴斯白绒山羊的产绒量、绒厚、毛长、体重、绒伸直长度和细度等六个性状的遗传参数进行了估测。结果表明:(1)绒量遗传力介于0.26~0.45之间;绒厚遗传力介于0.33~0.56之间;毛长遗传力介于0.23~0.32之间;体重的遗传力介于0.1 6~0.36之间;绒伸直长度遗传力为0.24;绒细度的遗传力为0.14。(2)产绒量与绒厚、绒厚与毛长、长度与绒厚、长度与毛长的遗传相关分别介于0.33~0.79、0.51~0.69 、0.38~0.60、0.74~0.90之间,存在较强的正向遗传相关;绒量与毛长、绒量与体重、绒厚与体重、细度与绒厚、细度与绒量、细度与体重的遗传相关分别为0.11~0.38、0 .06~0.17、0.15~0.36、0.02~0.11、0.24~0.35、0.13~0.32之间,存在较弱的正向遗传相关;毛长与体重、长度与绒量、长度与体重、长度与细度、细度与毛长之间的遗传相关介于-0.14~-0.28、-0.09~-0.20、-0.18~-0.23、-0.27~-0.31、-0 .17~-0.28之间,存在中等偏弱的负向遗传相关。(3)绒量、绒厚、毛长、体重的重复率分别为0.42、0.27、0.59、0.18。 相似文献
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Selected trace metals were analyzed in human malignant and nonmalignant (benign) breast tissue samples by the flame atomic absorption spectrophotometric method. In malignant tissues, dominant mean concentrations were revealed by Na, K, Ca, Mg, Fe, Zn, and Al at 927, 552, 231, 61.7, 36.5, 18.3, and 8.94 microg/g, respectively, while the mean metal levels in benign tissues were 903, 435, 183, 63.3, 24.7, 14.5, and 10.1 microg/g, respectively. Average concentrations of Cd, Co, Cr, Cu, Fe, Mn, K, Ca, and Zn were noted to be significantly higher in the malignant tissues compared with the benign tissues. Significantly strong correlations (r > 0.50) in malignant tissues were observed between Mn and Co, Mn and Cd, Cd and Cr, Fe and Mn, Cd and Co, Fe and Co, Mg and Pb, Cd and Fe, Mg and Ni, Pb and Ni, Ni and Sr, and Fe and Pb, whereas, Cd and Co, Cd and Mn, Co and Mg, Co and Mn, Cu and Mn, Co and Ni, Mg and Ni, Cd and Cu, Cd and Ni, Ca and Mg, Mn and Pb, Cu and Ni, Fe and Ni, Cd and Mg, Co and Cu, Cr and Na, and Cd and Cr revealed strong and significant relationships in benign tissues at p < 0.001. Principal component analysis of the metals data yielded six principal components for malignant tissues and five principal components for benign tissues, with considerably different loadings, duly supported by cluster analysis. The study revealed a considerably different pattern of distribution and mutual correlations of trace metals in the breast tissues of benign and cancerous patients. 相似文献
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头面部特征是人类学各人种进行分类的重要依据,在人类学的研究中被用作亲缘关系的证据。2006-2016年在四川、云南、西藏、贵州、海南、新疆、内蒙古共调查14个族群成人2989人(男性1434人,女性1555人)的16项头面部指标,比较这些族群头面部特征差异。研究结果如下:1)在男性族群中木雅人、尔苏人、临高人、白马人的面宽、头宽均较大。图瓦人、布里亚特人、摩梭人的面宽、头宽、形态面高、鼻高值均较大。僜人、革家人、莽人的面宽、头宽较小,而形态面高、鼻高值较大。空格人的面宽、头宽、形态面高、鼻高值均较小。2)在女性族群中图瓦人、布里亚特人的头宽、面宽、鼻高、耳上头高均较大。革家人、空格人的头宽、面宽、鼻高、耳上头高均较小。木雅人、尔苏人、八甲人、白马人、夏尔巴人的头宽、面宽较大,鼻高、耳上头高较小。僜人、克木人、莽人的头宽、面宽较小,而鼻高、耳上头高较大。3)头宽、容貌耳长跟纬度、年平均气温、年降雨量等环境因子相关性较高。4)通过聚类分析和主成分分析木雅人、尔苏人、白马人与羌族头面部特征比较接近。克木人与佤族头面部特征最为接近。革家人、僜人、莽人头面部特征比较接近。图瓦人、布里亚特人头面部... 相似文献
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【目的】对白背飞虱Sogatella furcifera唾液腺蛋白进行鉴定及功能注释分类,探究不同发育阶段和不同性别的白背飞虱唾液腺蛋白之间的区别与联系。【方法】麻醉白背飞虱若虫、雄成虫和雌成虫,解剖收集唾液腺组织,提取蛋白,还原烷基化和酶解,利用液相色谱串联质谱技术鉴定蛋白。与Unigene蛋白数据库进行比对,并通过KOG分析,对唾液腺蛋白进行功能注释分类。【结果】白背飞虱若虫、雄成虫和雌成虫特有的唾液腺蛋白分别为385, 168和82个,若虫与雄成虫、若虫与雌成虫及雄成虫与雌成虫共有的唾液腺蛋白分别为319, 60和60个。KOG功能注释显示与细胞过程和信号传导相关的蛋白数量最多,若虫、雄成虫和雌成虫特有以及若虫与雄成虫、若虫与雌成虫及雄成虫与雌成虫共有的这类蛋白数量分别为81, 22, 70, 19, 21和12个,这些蛋白主要发挥着翻译后修饰、蛋白质更新、伴侣蛋白,细胞内运输、分泌和囊泡运输及信号转导作用。【结论】白背飞虱唾液腺蛋白在参与信号转导机制方面表现较为活跃,这可能与其刺吸危害有一定的关系。 相似文献
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沙尘暴的危害及农业防治措施 总被引:3,自引:0,他引:3
沙尘暴是一种灾害性天气现象,它的发生与地表植被状况有密切关系,冬春季节农田裸露和退化草地植被覆盖度低是沙尘暴的主要沙尘来源,采用农业措施整治裸露农田和退化草地是沙尘源治理的关键。本文从沙尘暴的时空分布特征、沙尘暴成因、沙尘暴的危害和沙尘暴的农业防治措施等方面进行了论述,强调了以农业措施作为沙尘源治理技术核心的观点。农业措施主要包括:(1)调整农业种植结构,改变北方目前单一的种植方式,推广粮草混作技术、粮草间作套种、草田轮作,将牧草和越冬作物(冬小麦、冬牧70黑麦等)引入农田耕作系统,增加农田冬春季节的地表覆盖;(2)推广保护性耕作制度,通过免耕、提高留茬量和留茬高度,增加冬春季根茬固土能力和地表秸秆覆盖;(3)加强草原保护和建设,通过严禁新的草原开垦,严格限制超载放牧,禁止滥采滥挖,推广分区轮牧和舍饲圈养,加大围栏封育的力度等措施恢复和重建草原植被;(4)发展集约化农牧业,推广集约化种植和养殖技术,把人们的生产活动集中在条件较好的土地上,减少沙化农田和草地压力。 相似文献
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Meristematic cells of Vicia faba L. were labeled with rabbit anti-actin antibody and FITC-conjugated goat anti-rabbit lgG antibody and observed with fluorescence microscopy. Both the nuclei and chromosomes sent forth distinctive fluorescence, indicating that actin is present in the nuclei and chromosomes. Sections were reacted with the anti-actin antibody and protein A-colloidal gold and observed with transmission electron microscopy. Gold particles were found over the whole nuclei, and a lot of particles were concentrated in condensed chromatin areas and nucleoli, confirming the observations with the fluorescence microscopy. V. faba nuclei and chromosomes were treated with DNase Ⅰ and 2 mol/L NaC1, and DNA and histone-depleted nuclei and chromosomes were obtained. Indirect immunofluorescence tests showed that the DNA and histone-depleted nuclei and chromosomes reacted positively with the anti-actin antibody. These results demonstrated that actin exists not only in intact nuclei and chromosomes but also in DNA and histone-depleted nuclei and chromosomes of V. faba. In addition, the authors' results indicate that tropomyosin is present in the nuclei and chromosomes of V. faba. Presence of actin in nuclei and chromosomes as well as in DNA and histone-depleted nuclei and chromosomes of higher plants is discussed. 相似文献
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Neuropeptide B and W regulate leptin and resistin secretion, and stimulate lipolysis in isolated rat adipocytes 总被引:1,自引:0,他引:1
Skrzypski M Pruszyńska-Oszmałek E Ruciński M Szczepankiewicz D Sassek M Wojciechowicz T Kaczmarek P Kołodziejski PA Strowski MZ Malendowicz LK Nowak KW 《Regulatory peptides》2012,176(1-3):51-56
Neuropeptide B (NPB) and W (NPW) regulate food intake and energy homeostasis in humans via two G-protein-coupled receptor subtypes, termed as GPR7 and GPR8. Rodents express GPR7 only. In animals, NPW decreases insulin and leptin levels, whereas the deletion of either NPB or GPR7 leads to obesity and hyperphagia. Metabolic and endocrine in vitro activities of NPW/NPB in adipocytes are unknown. We therefore characterize the effects of NPB and NPW on the secretion and expression of leptin and resistin, and on lipolysis, using rat adipocytes. Isolated rat adipocytes express GPR7 mRNA. NPB and NPW are expressed in macrophages and preadipocytes but are absent in mature adipocytes. Both, NPB and NPW reduce the secretion and expression of leptin from isolated rat adipocytes. NPB stimulates the secretion and expression of resistin, whereas both, NPB and NPW increase lipolysis. Our study demonstrates for the first time that NPB and NPW regulate the expression and secretion of leptin and resistin, and increase lipolysis in isolated rat adipocytes. These effects are presumably mediated via GPR7. The increase of resistin secretion, stimulation of lipolysis and the decrease of leptin secretion may represent mechanisms, through which NPB and NPW can affect glucose and lipid homeostasis, and food intake in rodents. 相似文献
10.
《Reproductive biology》2020,20(2):254-258
We examined the effects of metabolic hormones leptin and ghrelin, and the oil-related environmental contaminants toluene and xylene on the release of ovarian hormones by gravid and non-gravid cats, as well as the functional interrelationships between metabolic hormones and contaminants. Ovarian fragments of non-gravid cats were cultured with and without leptin and toluene. Next, ovarian fragments of either non-gravid or gravid animals were cultured with and without ghrelin and xylene. Oxytocin (OT) and prostaglandin F (PGF) release was measured using ELISA.We confirm ovarian OT and PGF production by feline ovary, demonstrate the involvement of leptin and ghrelin in controlling OT and PGF release, show the direct influence of toluene and xylene on feline ovarian secretory activity, indicate the ability of leptin and ghrelin to mimic and promote the main contaminant effects, demonstrate that oil-related contaminants can prevent and even invert the effects of leptin and ghrelin on the ovary, and suggest the gravidity-associated changes in ability of ghrelin to promote xylene action on PGF (but not to OT), but not in basic ovarian OT and PGF release and their response to ghrelin or xylene. 相似文献
11.
自然生态价值、生态资产管理及价值实现的生态经济学基础研究——科学概念、基础理论及实现途径 总被引:1,自引:0,他引:1
自然界的生态系统为人类繁衍发展提供各式各样的生活、生产和生计的环境条件与自然资源。基于自然规律的生态系统管理是人类社会不断认知自然生态价值、保护利用自然环境和资源、创造积累生态资产、维持社会经济系统永续发展的基本途径。以此为核心认知的区域生态经济学或经济生态学,正在成为探讨人类世地球系统演变及社会经济可持续发展问题的科学研究前沿。本文以大尺度区域宏观生态系统科学为学术视角,以生态系统的多功能性与多元价值观为基础,综合论述了自然生态价值、生态资产、生态产品等基本概念;从生态学、社会学和经济学融合角度,分析讨论了生态资产形成与变化、生态产品生产与消费、生态投资与生态资产损益等过程原理;提出了区域生态资产的系统经营与生态价值实现途径,期望为我国及区域生态系统价值及生态资产的评估,生态产业及生态价值实现体系的发展提供理论和方法学参考。 相似文献
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《Peptides》2016
This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). 相似文献
13.
Light and heavy fractions of soil organic matter in response to climate warming and increased precipitation in a temperate steppe 总被引:2,自引:0,他引:2
Soil is one of the most important carbon (C) and nitrogen (N) pools and plays a crucial role in ecosystem C and N cycling. Climate change profoundly affects soil C and N storage via changing C and N inputs and outputs. However, the influences of climate warming and changing precipitation regime on labile and recalcitrant fractions of soil organic C and N remain unclear. Here, we investigated soil labile and recalcitrant C and N under 6 years' treatments of experimental warming and increased precipitation in a temperate steppe in Northern China. We measured soil light fraction C (LFC) and N (LFN), microbial biomass C (MBC) and N (MBN), dissolved organic C (DOC) and heavy fraction C (HFC) and N (HFN). The results showed that increased precipitation significantly stimulated soil LFC and LFN by 16.1% and 18.5%, respectively, and increased LFC:HFC ratio and LFN:HFN ratio, suggesting that increased precipitation transferred more soil organic carbon into the quick-decayed carbon pool. Experimental warming reduced soil labile C (LFC, MBC, and DOC). In contrast, soil heavy fraction C and N, and total C and N were not significantly impacted by increased precipitation or warming. Soil labile C significantly correlated with gross ecosystem productivity, ecosystem respiration and soil respiration, but not with soil moisture and temperature, suggesting that biotic processes rather than abiotic factors determine variations in soil labile C. Our results indicate that certain soil carbon fraction is sensitive to climate change in the temperate steppe, which may in turn impact ecosystem carbon fluxes in response and feedback to climate change. 相似文献
14.
沙漠化对科尔沁沙质草地生态系统碳氮储量的影响 总被引:1,自引:0,他引:1
通过野外调查,研究了沙漠化对科尔沁沙质草地生态系统碳、氮储量的影响.结果表明:沙漠化对草地碳、氮含量和储量具有显著影响,随着草地沙漠化的进程,草地碳、氮含量和储量明显下降.与非沙漠化草地相比,轻度、中度、重度和严重沙漠化草地0~100cm深土壤有机碳和全氮含量分别下降了56.06%和48.72%、78.43%和74.36%、88.95%和84.62%、91.64%和84.62%,植物组分中的碳、氮含量分别下降了8.61%和6.43%、0.05%和25.71%、2.58%和27.14%、8.61%和27.86%;轻度、中度、重度和严重沙漠化草地地上植物组分中的碳、氮储量分别下降了25.08%和27.62%、30.90%和46.55%、73.84%和80.62%、90.89%和87.31%,0~100cm深地下植物组分中碳和全氮储量分别下降了50.95%和43.38%、75.19%和71.04%、86.76%和81.48%、91.17%和83.17%.2000年科尔沁沙地沙漠化草地总面积为30152.7km2,因沙漠化损失的碳、氮总储量高达107.53和9.97Mt.草地碳、氮含量的下降主要源于风蚀过程中土壤细颗粒的损失.土壤的粗化和贫瘠化最终导致了植物和凋落物中碳、氮储量的明显下降. 相似文献
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通过田间调查,研究了棉铃虫卵和龟纹瓢虫、中华草蛉空间分布的关系。研究表明,棉铃虫卵和龟纹瓢虫、中华草蛉在棉株垂直各层上的数量间相关系数6月分别为0.5696、0.8620,7月为0.8300、0.9282,8月为0.9083、0.8201,除6月龟纹瓢虫外,其余皆达显着或极显着水平;垂直格局上棉铃虫卵和龟纹瓢虫扩散系数和久野指数间相关系数分别为0.8211、0.7791,皆达极显着水平;水平格局上棉铃虫卵和中华草蛉扩散系数和久野指数间相关系数分别为0.7925、0.5228,分别达极显着和显着水平。 相似文献
16.
Nathalie Gontier 《Evolutionary biology》2016,43(4):427-445
The natural world demonstrates signs of spatial–temporal order, an order that appears to us through a series of recognizable, recurring and consecutive patterns, i.e. regularities in forms, functions, behaviors, events and processes. These patterns lend insight into the modes and tempos of evolution and thus into the units, levels, and mechanisms that underlie the evolutionary hierarchy. Contributors to this special issue analyze converging patterns in the biological and sociocultural realm across and beyond classic divisions between micro- and macro-evolution; horizontal/reticulate and vertical evolution; phylogeny, ontogeny and ecology; synchronic and diachronic sociocultural and linguistic research; and tree and network diagrams. Explanations are sought in complexity theory, major transitions of evolution, and process and mechanism approaches to change; and consequences for notions such as “life”, “species”, “biological individuality”, “units” and “levels” of evolution are given. 相似文献
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The postthaw motility and fertility of buffalo and cattle semen is reduced when they are cryopreserved for artificial insemination. In the present study, an attempt was made to characterize the cryogenic changes in proteases and antiprotease activities (APA) of buffalo and cattle semen because these proteolysis regulators have been reported to be associated with sperm motility and fertility. Buffalo sperm demonstrated at least two major proteases of 45 and 42 kDa and three minor proteases of 95, 52, and 33 kDa. Similarly, cattle sperm demonstrated three major proteases of 62, 45, and 42 kDa and two minor proteases of 85 and 78 kDa. Buffalo seminal plasma demonstrated at least three major proteases of 78, 68, and 62 kDa and one minor protease of 98 kDa and cattle seminal plasma demonstrated one major protease of 68 kDa and two minor proteases of 78 and 75 kDa. Except for the 45 kDa protease, most of the previously mentioned proteases were found to be metalloproteinases. Compared with fresh sperm, cryopreserved buffalo and cattle sperm demonstrated a major protease band of 52/49 kDa and the activity of this protease reduced progressively with the duration of cryopreservation. On the contrary, compared with the fresh seminal plasma, cryopreserved buffalo and cattle semen extenders displayed the presence of a new protease band of 45 kDa and demonstrated that this protease activity was leaked from buffalo and cattle cryopreserved spermatozoa. Buffalo and cattle seminal plasmas displayed at least two major APA of 86 and 26 kDa. Compared with buffalo, cattle seminal plasma demonstrated significantly greater APA. Thus, the present study demonstrated the presence of an array of proteases and APA in buffalo and cattle semen and the activities of which changed during cryopreservation. The leakage of the specific protease activity and changes in the proteases and APA might be attributed to reduced motility and fertility of cryopreserved semen in these species. 相似文献
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《Cryobiology》2020
Melatonin has the ability to improve plant growth and strengthened plant tolerance to environmental stresses; however, the effects of melatonin on mitochondrial respiration in plants and the underlying biochemical and molecular mechanisms are still unclear. The objective of the study is to determine possible effects of melatonin on mitochondrial respiration and energy efficiency in maize leaves grown under optimum temperature and cold stress and to reveal the relationship between melatonin-induced possible alterations in mitochondrial respiration and cold tolerance. Melatonin and cold stress, alone and in combination, caused significant increases in activities and gene expressions of pyruvate dehydrogenase, citrate synthase, and malate dehydrogenase, indicating an acceleration in the rate of tricarboxylic acid cycle. Total mitochondrial respiration rate, cytochrome pathway rate, and alternative respiration rate were increased by the application of melatonin and/or cold stress. Similarly, gene expression and protein levels of cytochrome oxidase and alternative oxidase were also enhanced by melatonin and/or cold stress. The highest values for all these parameters were obtained from the seedlings treated with the combined application of melatonin and cold stress. The activity and gene expression of ATP synthase and ATP concentration were augmented by melatonin under control and cold stress. On the other hand, cold stress reduced markedly plant growth parameters, including root length, plant height, leaf surface area, and chlorophyll content and increased the content of reactive oxygen species (ROS), including superoxide anion and hydrogen peroxide and oxidative damage, including malondialdehyde content and electrolyte leakage level; however, melatonin significantly promoted the plant growth parameters and reduced ROS content and oxidative damage under control and cold stress. These data revealed that melatonin-induced growth promotion and cold tolerance in maize is associated with its modulating effect on mitochondrial respiration. 相似文献
19.
采用恒温土壤培养方法,研究了4种不同鱼蛋白有机液肥施用量[0(对照)、0.5、1.5、2.5 ml·kg-1]条件下小粉土酶活性和微生物生物量碳、氮的变化,及其与土壤养分的相关关系.结果表明:在整个培养过程中,不同鱼蛋白有机液肥施用量处理下土壤pH值变化范围为7.07~7.31,与对照无显著差异;土壤磷酸酶活性显著增强,分别为对照的1.27、1.90、1.96倍;土壤脲酶活性分别比对照提高39.81%、78.06%、173.24%;蛋白酶活性比对照提高56.37%、108.29%、199.98%;土壤微生物生物量碳、氮均随肥料添加量的增加而逐渐增大,分别为对照的1.67、3.95、4.74倍和1.21、2.43、4.06倍.土壤脲酶和蛋白酶活性以及土壤微生物生物量碳、氮在不同施用量处理下达到峰值点的时间不同.土壤磷酸酶、脲酶和蛋白酶活性、土壤微生物生物量碳、氮与土壤养分均呈显著正相关.施用鱼蛋白有机液肥可以显著促进小粉土微生物的生长及酶活性的提高,从而促进土壤有机质的分解转化和速效养分的释放. 相似文献
20.
Variance and covariance components for liability of piglet survival during different periods 总被引:1,自引:0,他引:1
Variance and covariance components for piglet survival in different periods were estimated from individual records of 133 004 Danish Landrace piglets and 89 928 Danish Yorkshire piglets, using a liability threshold model including both direct and maternal additive genetic effects. At the individual piglet level, the estimates of direct heritability in Landrace were 0.035, 0.057 and 0.027, and in Yorkshire the estimates were 0.012, 0.030 and 0.025 for liability of survival at farrowing (SVB), from birth to day 5 (SV5) and from day 6 to weaning (SVW), respectively. The estimates of maternal heritability for SVB, SV5 and SVW were, respectively, 0.057, 0.040 and 0.030 in Landrace, and 0.050, 0.038 and 0.019 in Yorkshire. Both direct and maternal genetic correlations between the three survival traits were low and not significantly different from zero, except for a moderate direct genetic correlation between SVB and SV5 and between SV5 and SVW in Landrace. Direct and maternal genetic correlations between piglet birth weight (BW) and SV5 were moderately high, but the correlations between BW and SVB and between BW and SVW were low and most of them were not significantly different from zero. These results suggest that effective genetic improvement in piglet survival before weaning by selection should be based on both direct and maternal additive genetic effects and treat survival in different periods as different traits. 相似文献