皖西白鹅雄鹅种龄与生殖激素水平关系的研究

实验结果显示，各龄雄鹅在非生殖期血清中促黄体生成素（LH）、促卵泡刺激素（FSH）和雌二醇（E2）在血清中的含量都低于5.0 mu/ml，其差异性难以比较.4种不同种龄的雄鹅在垂体泌乳素（PRL）和孕酮（P）水平上没有显著差异.在睾酮（T）激素水平上差异很明显，即2龄种鹅＞1龄种鹅＞3龄种鹅＞4龄种鹅.可见在4个种龄的雄鹅中，2龄种鹅体内的睾酮最高，其生殖能力可能最强。     

Biological parameters of the endangered fish Chitala chitala (Osteoglossiformes: Notopteridae) from some Indian rivers

Age, growth and maturity data of the freshwater feather back Chitala chitala (Hamilton-Buchanan, 1822) were collected from ten different geographical locations. Out of ten populations, maximum 6+ ages were recorded from four river basins namely river Bhagirathi, Koshi, Saryu and Ganga and the back calculated lengths at 6+ ages ranged from 1033.36–1073.63 mm. In rest of the locations, however, only 3+ age classes were recorded. Specific rate of linear growth (C_l) and specific rate of weight increase (C_w) showed decreases except in two locations. The specific rate of linear growth (C_l) and the specific rate of weight increase (C_w) increased at 3+ age class in the river Bhagirathi. Among other growth parameters, three distinct life stages of C. chitala were observed based on analysis of growth constant data. Analysis of variance (ANOVA) of the back-calculated length data of 10 populations indicated a significant difference (p < 0.05). Out of ten populations studied, six showed significant variation of growth in 1+ age class and two showed significant variation in 2+ to 6+ age classes. Length-weight relationship of the species from all the population was calculated and the coefficient of correlation (r) was at the significant level where the value of ‘b’ was almost 3 for all the locations studied. Male C. chitala attained maturity earlier (2+ age) whereas females matured at age 3+. The percentages of mature individuals also varied between river basins. Based on this study strategies can be proposed for sustainable exploitation of the species from wild populations.     

基于当量积温的春玉米叶龄模式研究

提前了解玉米叶龄情况,既能使采用叶龄施肥方法的农民提前做好准备,也能了解玉米穗分化的情况,对玉米田间管理有重要意义,为更好的实现精准农业管理提供一种方法。基于2012—2014年佳木斯农气站、梨树农气站、榆树农气站的春玉米每年5个大田分期播种试验资料,应用当量积温模式分析春玉米出苗期—抽雄吐丝期叶龄与当量积温的关系。结果表明：通过上述研究建立春玉米叶龄生长模式,实现玉米叶片生长的定量模拟。模型结果很好地通过显著性检验。在不发生干旱的情况下,可以用该模型模拟黑龙江和吉林地区‘先玉335’的叶龄,也可根据天气预报预测未来该品种春玉米叶龄。     

Analysis on age structure of Zoysia japonica（Poaceae） population

The age-structure of natural population of Zoysia japonica in Xiuyan County of Liaoning Province was studied by generational method.The results showed that the highest tiller age class was three,but 1st age class tillers held dominant position with proportions over 95% in each month during the growing seasons.The 2nd age class and 2rd age class tillers were minority in the population.So Z.japonica population was an expanding population.The zero age class buds on the rhizomes were dominantin buds age structures.The proportion of buds to tillers on quantity in each month was about 30% to 40% and reached the highest at the end of September.The increasing of buds proportion before dormancy guaranteed the quantity of tillers in the next spring.The biomass of 1st age class tillers changed with time.The biomass kept increasing from April to July and reached the highest at the end of July and then decreased.     

濒危植物四合木结实特性与植株年龄和生境关系的研究

研究了濒危植物四合木种群初次结实年龄 ,果实空间分布、果实数量、果实重量、结籽率、花果转移率随年龄和生境的变化规律。结果表明 :四合木种群初次结实年龄为 4a。果实的空间分布为树冠上部 >中部 >下部 ,上、中部显著高于下部。平均单株果实的数量分布随年龄变化曲线呈山峰型。在 4～ 1 8a范围内 ,随着年龄增大 ,结实量增加 ,到 1 8a以后 ,随着年龄增加 ,结实量逐渐减少 ,1 3～ 2 7a为结实高峰期。果实重量随年龄变化趋势与果实数量随年龄变化趋势基本一致。在自然状态下 ,四合木结籽率为 1 2 6%～ 2 80 % ,花果转移率为 5 4 3 9%～ 71 43 % ,结籽率、花果转移率与年龄的关系呈双峰型。结籽率低的主要原因为 :( 1 )传粉过程受到障碍 ,即传粉媒介 (昆虫 )的访花频率极低 ,使得柱头上的花粉量受到限制。这是结籽率低的内因。( 2 )土壤水分供应不足 ,从而使胚珠不能正常发育。这是导致结籽率低的外因。     

结缕草种群年龄结构的研究

本文用世代的方法对辽宁省岫岩县天然结缕草种群的年龄结构进行了研究。结果表明:结缕草无性系种群分蘖株的最高龄级为3龄。在生长季中均以1龄蘖为主,各月比例均占95%以上。2龄、3龄的分蘖株数量很少。因此,结缕草为增长型种群。芽的年龄构成以0龄根茎芽为主,芽数量基本为分蘖株数量的30%-40%,休眠前芽数量增加,这保证了来年种群分蘖数量的稳定。1龄蘖的生物量在整个生长季中的变化动态是:从4-7月呈递增趋势,在7月末达到最高点,然后下降。图1表3参9。     

结缕草构件种群年龄结构与动态的研究

研究了沈阳辉山野生结缕草叶片的生死动态,确定了不同生活年限的结缕草分蘖和根状茎的形态特点.通过形态鉴别的方法确定了结缕草各构件的年龄特征,研究了构件种群的年龄构成及其动态变化规律.结缕草的分蘖和根状茎的最高生活年限均为3年.在一个生长季中,2年生分蘖株和根状茎的绝对优势地位逐渐被1年生分蘖株和根状茎取代.芽库在生长季初和生长季末储量较高,旺盛生长季节基本稳定.结缕草分蘖、芽和根状茎的季节动态是维持结缕草无性系种群持续稳定存在的一个根本保证.     

Prevalence and age-related infection of Cryptosporidium suis, C. muris and Cryptosporidium pig genotype II in pigs on a farm complex in the Czech Republic

A total of 413 pig faecal samples were collected from pre-weaners (119), starters (131), pre-growers (123) and sows (40) from a farm with a closed breeding system segmented into two breeding complexes and a growing complex in the region of Vysočina, Czech Republic and screened for the presence of Cryptosporidium using staining methods and genotyping (SSU rRNA). Cryptosporidium oocysts were detected by microscopy in the faeces of 21.1% of the samples (87/413). Sequence analyses and RFLP identified C. suis in 44, Cryptosporidium pig genotype II in 23 and C. muris in 2 samples. No mixed infections were found.Pigs under 7 weeks of age were infected with C. suis only. Cryptosporidium pig genotype II was found in animals from 7 weeks of age. No relationship was found between diarrhoea and any Cryptosporidium infection in any of the different age groups (P < 0.05). The pre-weaned pigs shed significantly more Cryptosporidium oocysts than older pigs and it was associated with C. suis infection.     

Genetic and phenotypic parameters of milk yield, milk composition and age at first kidding in Saanen goats from Mexico

A total of 4007 lactation records from 1520 Saanen goats kidding from 1999 to 2006 and obtained from 10 herds in Guanajuato, Mexico, were analyzed to estimate the heritabilities, repeatabilities, as well as genetic, environmental and phenotypic correlations for milk yield (MILK), fat yield (FAT), protein yield (PROT), fat content (%FAT), protein content (%PROT) and age at fist kidding (AFK). A five-trait repeatability model was used to estimate (co)variances for milk traits, and a four-trait animal model for first lactation records was used to estimate (co)variances involving AFK. For MILK, FAT, PROT, %FAT, %PROT and AFK, heritability estimates were 0.17 ± 0.04, 0.19 ± 0.05, 0.17 ± 0.04, 0.32 ± 0.06, 0.38 ± 0.07 and 0.31 ± 0.09, respectively. Repeatabilities for MILK, FAT, PROT, %FAT and %PROT were 0.43 ± 0.02, 0.42 ± 0.02, 0.42 ±0.02, 0.64 ± 0.02, and 0.63 ± 0.02, respectively. The genetic correlations between MILK and FAT, and between MILK and PROT, were high and positive (0.72 ± 0.08 and 0.87 ± 0.04, respectively). Genetic correlations between MILK and %FAT, between MILK and %PROT and between MILK and AFK, were − 0.24 ± 0.16, − 0.30 ± 0.15 and − 0.18 ± 0.23, respectively. Genetic correlations between AFK and FAT and between AFK and PROT were − 0.09 ± 0.24 and − 0.17 ± 0.25, respectively; and genetic correlations between AFK and %FAT and between AFK and %PROT were 0.29 ± 0.35 and 0.14 ± 0.27, respectively. Selection for milk traits is possible using a repeatability animal model. Selection for milk production traits would probably not increase AFK, but more precise estimates of the genetic correlations are required. Selection to lower AFK is possible. These (co)variance estimates would make it possible to predict the selection responses from different economic indices in order to maximize the economic responses for the local markets.     

银狐的繁殖年龄和配种日期对繁殖性能的影响

本试验通过对816只母银狐的1 195个繁殖记录和51只公狐的211个繁殖记录进行了整理,统计分析了母银狐配种日期及公、母银狐年龄对主要繁殖性能的影响。结果表明:在唐山地区,母银狐2月29日前发情配种,产胎率和胎断奶成活仔兽数较高,而3月16日以后发情配种,其繁殖效率大大降低;1岁和5岁公银狐比2到4岁公银狐的配种或采精次数低,但1岁公银狐所配母银狐的平均受胎率和胎断奶成活仔兽数均高于其它年龄公银狐所配母银狐。