即浸蚕种不良卵剔除方法初探

即时浸酸散卵蚕种在催青期通过二次风选,较在催青前用盐水比选剔除不良卵更为有效,良卵率提高;同时,风选比盐水比选对蚕卵生理造成的损害程度小,实用孵化率提高,催青死卵、白死卵等减少,避免蚕种事故发生。     

浅析以粒数作为蚕种装盒标准的不合理性

１ 引述 蚕卵的大小，因品种不同而有差异。但蚕卵的大小与饲养条件，营养状况，季节等有无关系，由这些因素引起蚕卵大小的变化，对一代杂交种的饲养成绩有无影响，尚不明白。笔者通过近几年对原万县市７个场（站）同原种来源、同品种、同饲养季节、不同饲养场（站）生产的１４４８个批次的蚕种进行了调查。得知蚕卵的大小除因品种不同而有差异外，更与饲养条件、营养状况有很大的关系，见表１（以克卵粒数多少表示蚕卵的大小）。 从表可看出，品种不同克卵粒数不一样，但同一品种因饲养条件，营养状况不同克卵粒数相差很大。据调查，同样…     

蚕种不良卵的淘汰率和再发生率与蚕种质量关系

<正>我省目前蚕种质量以“四率”进行考核,即“良卵率、孵化率、杂交彻底率、微粒子毒率”,这是蚕种质量检验考核的一大进步.孵化率、杂交彻底率、微粒子毒率都可以通过直接检验比较公正地反映蚕种内在质量,而良卵率指标在蚕种生产后期处理中易受人为因素的干扰,不能准确地反映蚕种的内在质量.在实际考核中,考核结果也没有与蚕种结算价格挂钩.我们在生产中发现冷浸种不良卵的淘汰率和越年种不良卵的再发生率与蚕种质量有很大的内在关系.     

转青蚕种冷藏后再出库饲养情况初探

蚕品种白玉×秋丰的转青蚕卵经冷藏13 d后收蚁饲养,实用孵化率春蚕仍达95.3%、晚秋蚕仍达97.1%;春蚕的盒种产茧量为44.9 kg,比对照区(47.1 kg)低4.7%;晚秋蚕为45.5 kg,比对照区(47.3 kg)低3.8%.春蚕的结茧率为97.7%,比对照区(98.2%)低0.5个百分点;晚秋蚕为98.1%比对照区(98.4%)低0.3个百分点.春蚕的蚕期发病率为0.39%,比对照区(0.19%)高0.2个百分点;晚秋蚕为0.21%,比对照区(0.10%)高0.11个百分点.白玉×秋丰的转青蚕卵经冷藏13 d后饲养的各项成绩稍差于对照区,在生产中一般不提倡用冷藏抑制后的转青蚕卵饲养,可用于因特殊原因需要少量补购蚕种饲养,但转青蚕卵冷藏时以不超过10 d为宜.     

电晕人工孵化两广二号蚕种试验

家蚕卵滞育的人工解除研究对养蚕业具有重要意义。为深入探索电晕人工孵化技术在蚕业生产中的应用,以两广二号为试验蚕种利用电晕放电刺激蚕种,使其孵化。结果表明,电晕能有效阻止两广二号产后约20 h的蚕卵进入滞育而达到人工孵化效果,与即时浸酸处理效果一致。进一步摸索了不同放电电压、刺激时间对电晕人工孵化两广二号正反交蚕种孵化率的影响,发现两广二号正反交蚕种在8 kV、1~5 min处理条件下的实用孵化率最高;电压过高或电击时长过长均会造成死卵率增加;而且电晕人工孵化两广二号反交的电压与时间范围比正交要窄。     

蚕种冬季浴消

越年蚕种的浴消、整理是蚕种生产过程中重要一环,浴消整理工作是否适时合理、细致认真,直接影响蚕种的良卵率和孵化率,是提高蚕种质量的关键之一,必须按照蚕卵冬季生理要求,掌握标准,认真操作,杜绝差错,做好冬季浴种工作。1蚕种浴消日期的确定蚕种浴消时间的迟早与蚕种孵化率有着密切关系,因为在浴消过程中,各种操作都能使蚕卵受到物理刺激,加快蚕卵的活性化。浴消过早,浴消后蚕卵容易遇到高温,部分已活性化的蚕卵胚胎会加快发育,这些蚕卵胚胎在低温冷藏抑制中,对低温抵抗力减弱,便会造成蚕种孵化不齐和催青死卵等。浴消过迟,蚕卵已解除滞育…     

湖州市蚕种质量存在的问题及对策

湖州市蚕种质量存在的问题及对策湖州市农业法规站沈根生，吴凤祥，黄德华１９９４年蚕种生产夺得了又一个丰收年，全市生产毛种２３１．５７万张，估计净种１２３．５万张，预计完成计划的１０８．８％，蚕种质量从成品良卵率、实用孵化率、微粒子病毒率、杂交率等指标的...     

对蚕种质量若干问题的思考

影响桑蚕种质量的因素较多，但就普通种而言，直接影响丝茧育饲养成绩的主要是病毒率、杂交率、实用孵化率、良卵率、卵量及产附等。特别是做好准确检疫、防控微粒子病的胚种传染尤为重要。同时提高杂交率、实用孵化率和良卵率是农村丝茧育稳产高产的保证。     

再谈如何提高蚕种质量

蚕种质量内涵非常丰富,它是集遗传质量、蚕卵内在物质基础及加工生产质量于一体的一个系统质量体系.目前,对遗传质量、蚕卵内在物质基础尚难以量化,没有量化指标,只能借助生物工程技术,通过专家评审.而蚕种加工生产质量可以量化,国家规定的蚕种质量标准实质上就是蚕种加工质量的标准:即杂交率99%以上,良卵率98%以上,孵化率98%以上,毒率不能超过0.5%.因此,提高蚕种质量必须按照国家规定的四率标准,从以下几方面做起.     

应用“四率”检测 提高一代交杂蚕种质量

江苏蚕种由于品质优良,曾称"铁种",饮誉国内外.1980年以来,因原蚕区发展过快,虽然在数量上满足了蚕桑生产急速发展的需要,但质量上却发生了一些问题,致使部分场批蚕种微粒子毒率上升,杂交率、孵化率下降,不良卵率增加,引起蚕农的强烈反映.笔者认为应用"四率"(毒率、杂交率、孵化率、不良卵率)检测,加强质量管理是提高蚕种品质的强有力手段.     

鸡蛋、乌鸡蛋、鹌鹑蛋营养成分的测定比较

禽蛋是人们生活中的重要营养源,是天然食物中最理想的蛋白质。本试验测定了鸡蛋、乌鸡蛋和鹌鹑蛋中的水分、脂肪、蛋白质、磷脂、胆固醇、维生素B2和氨基酸的含量,通过数据对比分析,得到如下结果:乌鸡蛋具有较高的营养价值,鹌鹑蛋由于含有很高的胆固醇,并不适合老年人的食用。鸡蛋的蛋白质、磷脂和氨基酸含量均低于乌鸡蛋和鹌鹑蛋,其营养价值最低。     

The hen's egg: Density of egg shell and egg contents

One hundred eggs were used, from hens of seven widely differing strains: two commercial brown‐egg hybrids (one British, one American), two commercial white‐egg hybrids (one British, one Canadian), one broiler strain, one highly inbred strain of laboratory White Leghorns and one laboratory strain of Brown Leghorns. The volume occupied by the shell of each egg was estimated from its surface area—itself estimated by means of a three‐parameter model (Carter, 1968)— and its mean thickness, measured with an anvil micrometer. The volume occupied by the egg contents was estimated by subtracting the shell volume from the egg volume, which was also estimated by means of the three‐parameter model. Mean overall shell density (counting as “shell” all mineral matter and spaces between the outer surface of the mineral shell and a surface through the tips of the mammillae) was estimated, by regressing shell weight on shell volume, to be 2.241 ±0.004 g./cm.³; covariance analysis showed that the strains were homogeneous in this respect. Mean incremental shell density (i.e. the density of shell distal to the mammillary region) was estimated, by regressing shell weight per unit surface area on shell thickness, to be 2.386±0.004 g./cm.³; the strains were homogeneous in this respect too. The mean depth of the intermammillary spaces was estimated to be 19.9 μ. All the residual deviation from the common regression line can be attributed to measurement error. The estimated density of incremental shell is lower than that of calcite; the packing fraction of the crystals in the shell aggregate and/or the atoms in the crystals was estimated to be 92.8 per cent. The density of the egg contents (at the temperature of the bird) was estimated by regressing weight of contents on volume of contents; covariance analysis revealed significant differences between strains, one of the brown‐egg hybrids having the highest density of egg contents, 1.045 g/cm.³, and the laboratory Brown Leghorns the lowest, 1.033; both commercial white‐egg hybrid strains gave a value of 1.040 g./cm.³.     

The estimation of egg weight from egg gradings

A method is described for the estimation of mean egg weight from data giving the proportions of eggs in different weight grades. Tables are presented in which mean egg weights have been calculated for a range of grading figures, using both the British Egg Marketing Board and the European Economic Community grading systems.     

Mexican egg producer ranks as world's second largest egg company

PROAN公司是一家综合型现代化禽蛋生产商和动物蛋白食品供应公司. Prote í na动物有限公司(Prote i na Animal SA de CV)饲养了2 520万羽蛋鸡,是全球第二大、墨西哥和拉丁美洲第一大禽蛋生产商.该公司以首写字母缩写PROAN或“San Juan”蛋而被人们熟知.“San Juan”蛋以公司总部所在地圣胡安-德洛斯拉戈斯(San Juan de los Lagos)的名称命名,它地处墨西哥哈利斯科州(State of Jalisco)的洛斯阿尔托斯地区(Los Altos).     

The hen's egg: Incidence and inheritance of some egg abnormalities

1. More than 9000 eggs, each laid by a known hen, were examined and malformations of six types recorded: double‐yolked, A, B, rough, shell‐less and thin‐shelled.

2. A and B malformations are those seen in, respectively, an egg that is held in the shell gland for an abnormally long period and one that reaches the shell gland while an A‐egg is still there; many of the eggs recorded as rough‐shelled were probably A‐eggs for which the corresponding B‐eggs had been lost.

3. The birds were of three strains: a medium‐body‐weight brown‐egg‐laying strain and a White Leghorn strain, both of commercial origin, and a laboratory strain of Brown Leghorns.

4. The incidences of egg malformation in the three strains were 8.3, 9.2 and 0.5%.

5. A‐, B‐ and rough‐shelled eggs constituted more than two‐thirds of all malformed eggs.

6. Evidence from two generations suggests that these malformations have a high heritability.     

Mycoplasma gallisepticum vaccination: effects on egg transmission and egg production

The effects of Mycoplasma gallisepticum (MG) vaccination on egg transmission of MG and egg production were evaluated. Leghorn hens vaccinated with live MG (strain F), with strain F plus MG bacterin, with one dose of MG bacterin, or with two doses of MG bacterin all transmitted MG through the egg at a significantly lower level than unvaccinated controls. Hens vaccinated with two doses of MG bacterin had the longest lag before detectable transmission of MG through the egg. All vaccinated groups were protected against the egg-production drop seen in unvaccinated hens challenged with virulent MG.     

Heritabilities and correlations for egg shell crack frequency,body checking,egg number and egg weight in laying hens

1. Egg shell cracks and body checking were assessed on a total of 25 776 eggs collected from 744 hens of two selected White Leghorn strains between 65 and 72 weeks of age.

2. The sire‐component heritabilities in the two strains, respectively, were 0–59 ± 0.23 and 0.36 ± 0.20 for total cracks and 0.41 ± 0.20 and 0.49 ± 0.22 for body checking. The heritabilities for hole, star and hair cracks ranged from ‐0.03 ± 0.13 to 0.66 ± 0.24.

3. The frequency of total cracks did not bear any significant antagonistic relationship with body checking, egg number and egg weight. Body checking had variable relationship with egg number and egg weight. The correlations of shell cracks and body checking with each other and with egg number and egg weight appeared to vary between the strains.     

Partitioning of the response to protein between egg number and egg weight

1. Data from published trials with laying hens were examined to see whether the concentration of dietary protein needed to achieve maximum egg weight was greater than the amount needed to achieve maximum rate of lay. 2. It is concluded that both rate of lay and egg weight continue to show small responses up to the same level of protein (or limiting amino acid) input. 3. When predicting egg output using asymptotic models, a reasonable assumption is that small increments in dietary protein, close to the optimum, will evoke equal proportional responses in egg size and in rate of lay. 4. When protein supply is severely limiting, the major response is a reduction in rate of lay. Egg weight seldom falls below 0.90 of its maximum value, however inadequate the protein intake may be.