共查询到20条相似文献，搜索用时 15 毫秒
1.
1. Eggshell pieces (1 cm2) were decalcified using a solution of EDTA (200 g/litre, pH 6.9 to 7.0) in paraformaldehyde (2 g/litre) and glutaraldehyde (0.5 g/litre) in phosphate buffer. 2. They were prepared for transmission electron microscopy (TEM). 3. TEM identified a vertically aligned matrix associated with the vertical crystal layer (VCL). It is hypothesised that the vertical orientation of calcite crystals in the VCL is closely linked to this vertical matrix. 4. TEM also revealed the presence of a 2-layered cuticle, the inner layer containing vesicles which were absent in the outer. 5. Cuticular vesicles contain hydroxyapatite and are thought to play a role in the termination of shell formation. The current paper presents data relating to microbial apatitic systems that strengthen this hypothesis. 相似文献
2.
Broiler breeder pullets were exposed to constant 10-, 11-, 12-, 13-, 14- or 16-h photoperiods from 3 d of age. Egg weight, eggshell weight and shell thickness index were determined at 52 weeks of age. Egg weight increased by 0.31 g, shell weight decreased by 30 mg and shell thickness index decreased by 0.57 mg/cm2 for each one-hour increase in photoperiod. Whilst the changes in egg weight and eggshell thickness index might be overstated because eggs were collected at the same chronological time, the effect of time of egg-laying within the day was minimal in comparison, and did not negate the conclusion that egg weight increases, and shell weight and thickness index decrease with lengthening photoperiods. The effect of photoperiod on eggshell quality was not due to differences in the rate of lay between treatments. Shell weight was unaffected by time of lay. 相似文献
3.
1. The effect of replacing dietary cholecalciferol (D3) by 1 alpha,25-dihydroxycholecalciferol (1,25-(OH)2D3) on egg shell quality and egg production was tested on 32-week-old White Leghorn laying hens over 9 weeks. 2. Hens fed on a diet supplemented with 5 micrograms 1,25-(OH)2D3/kg diet, tended to lay more eggs, and the eggs had significantly higher specific gravity and percentage shell than eggs from control hens fed on a diet supplemented with 27.5 micrograms D3/kg diet. 3. The effect became apparent after about 4 weeks of treatment and persisted until the end of the test. 4. Hens fed on a diet without D3 supplement started to lay very thin or soft shelled eggs within 4 weeks, suggesting that the birds' reserves of D3 or its metabolites were depleted within this period. 5. The results suggest that 1,25-(OH)2D3 can be substituted for D3 in layer diets to improve egg shell quality. 相似文献
4.
1. Supplementing the drinking water of 50-week-old laying hens with sodium chloride (NaCl) concentrations between 0.5 and 2 g/l for 7 weeks significantly increased the incidence of egg shell defects and significantly decreased egg shell quality. Dietary NaCl concentrations between 0 and 2 g/kg had little effect on this response. 2. At similar total NaCl intakes egg shell defects were much greater when the NaCl was obtained from the drinking water rather than from the diet. 3. Hens producing eggs with defective shells as a result of receiving saline drinking water failed to recover the ability to lay eggs with good shells after 8 weeks on normal water. 4. The increased incidence of shell damage was not related to decreased food intake or increased egg weight or production. 相似文献
5.
1. A field study was conducted to investigate the deterioration of eggshell quality at the end of lay and examine the potential to extend the production cycle. A total of 1200 eggs were assessed originating from commercial farms in Belgium: eggs were random sampled at the collection belt at 57–65 weeks of age and at the end of the production cycle (74–92 weeks). 2. Based on a linear mixed model, egg quality was estimated for an average flock at 60 weeks of age and changes in quality traits were predicted until the end of the laying cycle. 3. Egg weight increased by 0.07 g every week from 60 weeks of age onwards and shape index decreased by 0.04 unit weekly (P < 0.001). Haugh unit values decreased weekly by 0.38 units whereas relative yolk weight was unaffected after 60 weeks of age. Relative albumen weight showed a weekly increase of 0.02% and relative shell decreased by 0.02% weekly until the end of lay. 4. Shell quality traits were also influenced by age: shell index decreased by 0.013 g weekly, shell thickness was calculated to be 0.23 µm thinner every week, deformation increased by 0.06 µm weekly from 60 weeks to the end of the laying cycle. Variability of the deformation of eggs indicated more heterogeneous shell quality at the end of the production cycle. Dynamic stiffness increased from 60 weeks of age on. 5. Laying hens were depopulated on average at 80 weeks of age (varying from 74–92 weeks). Although ageing had a significant effect on most of the egg quality traits, egg quality was still acceptable at the end of lay, indicating the potential to extend the laying cycle. 相似文献
6.
1. Laying hens were fed osteolathyrogens, either semicarbazide hydrochloride at 0.3 or 0.4 g/kg or β-aminopropionitrile fumarate at 0.5 or 0.6 g/kg diet to examine their effects on eggshell quality. 2. Shell quality characteristics considered for evaluation were shell surface area, shell thickness, shell weight, percentage shell, shape index and the specific gravity of eggs. Measurement of shell quality traits revealed that the hens fed osteolathyrogens laid eggs with significantly lower specific gravities and proportion of shell by weight. These differences were not explained by differences in shell thickness or weight or the shape index of eggs. 3. It was concluded that osteolathyrogens cause hens to lay eggs with poor shell quality and such eggs are weak and fragile. 相似文献
7.
This study set out to investigate if access to an enriched environment during the rearing phase influences subsequent production and eggshell quality in broiler breeders. Broiler breeder pullets were reared under standard rearing conditions (control treatment) or under standard conditions with an environmental enrichment of bales of plastic-wrapped wood shavings (enriched treatment). At 19 weeks of age both groups were transported to a laying facility and housed in standard pens according to treatment type. Egg weight, shape, shell thickness, non-destructive deformation, breaking strength, stiffness and ultrastructural quality were compared at beginning of lay (25 weeks old), peak production (31 weeks old), mid-lay (45 weeks old) and end of lay (57 weeks old). Production and hatchery data were also collected throughout lay. Significant treatment-age interactions were detected for non-destructive deformation, breaking strength and stiffness, such that birds which had received prior enrichment went on to maintain a better shell quality with age. The measurements of total shell thickness, mammillary thickness and effective shell thickness all showed a trend for a treatment-age interaction. Significant age effects were found for weight, shape index, shell thickness, breaking strength and stiffness. All production and hatchery data also demonstrated significant changes with age. It is concluded that early enrichment with bales of wood shavings may provide a novel approach to the maintenance of eggshell quality at a time when calcium metabolism begins to reduce in efficiency. 相似文献
8.
Three experiments are reported concerning the effect of the manganese content of the diet on the acid mucopolysaccharide content of egg shell matrix. In the first experiment hexosamine was taken as an index of acid mucopolysaccharide, but in experiments 2 and 3 uronic acid was determined instead. It was found that a low‐Mn diet depressed the hexosamine and uronic acid content of the matrix of eggs sampled at the start of lay. However, eggs from low‐Mn fed pullets after three months of lay showed a significant increase in matrix uronic acid. Other characteristics of shells from low‐Mn fed pullets taken at the start of lay were a low weight of shell per unit area and a high weight of matrix per unit area, which led to an abnormally high proportion of matrix to mineral in the shell. As a model for normal shell development eggs were extracted from the uterus at an early and late stage of shell formation. Although these uterine shells resembled the poor shells from the low‐Mn diet from the point of view of poor shell thickness and low matrix uronic acid content, the proportion of matrix to mineral in shell was similar to that of the fully‐formed shells and not as high as in shells from low‐Mn fed birds. This last observation led to the conclusion that low‐Mn shells were not unfinished products arising from a premature expulsion from the oviduct. 相似文献
9.
1. Laying hens were fed osteolathyrogens, either semicarbazide hy‐drochloride at 0.3 g/kg or β‐aminopropionitrile fumarate at 0.6 g/kg, to examine their effects upon the ultrastructure of shell and shell membranes by scanning electron microscopy. 2. Effects of the 2 lathyrogens were similar. Compared with the highly‐branched network of fine fibres in normal membranes, there is widespread lack of separation of fibres in lathyritic specimens and hence, uneven distribution of nucleation sites. Pores are also uneven in size and distribution, which can account for increased permeability. 3. Establishment between shell and membranes is reduced. Within the cone layer both type A and type B mammillary bodies occur. Large interstitial spaces and late fusion of the palisade layer indicate reduced resistance to fracture. 相似文献
10.
In the early postnatal period, the permeability of the piglet small intestine is high to compensate for the absence of trans-placental transfer of immunoglobulins during the fetal period. Vesicles, which mainly reflect the uptake of macromolecules and other colostral/milk components, were studied in three different regions of the small intestine – proximal, mid and distal – in a total of twelve piglets on day 0 (unsuckled and colostrums-fed), 2 and 6 (all suckled). Tissues were sampled and prepared for light microscopy (paraffin and cryo) and trans-electron microscopy. Different methods were applied to visualize cytoplasmatic subcellular components such as fat (Oil red O) and carbohydrates (PAS). Appearance and morphology of the epithelial vesicles were compared. In the proximal region several small supranuclear and a single large subnuclear electron dense, eosinophilic and PAS+ vesicle were present. They disappeared after 2 days (gut closure) and on day 6 adult-looking epithelial cells were present. In the distal region of day 0 pigs digestion vesicles/flocculent vesicles were observed in the cytoplasma. The vesicles appeared empty but with eosinophilic, PAS+ and electron dense precipitations. The size and variation of these vesicles increased with age. Fat absorption increased markedly from day 2 to day 6. The observations indicate that in general colostral absorption processes are initiated prenatally, persist after birth and in the distal region also after gut closure. Fat absorption increased after gut closure, and in the distal region the increase correlated with e.g. IgG absorption. 相似文献
11.
The carotid body of the goat was found to be a small oval or rounded parenchymatous organ. It was characterized by its profound vascularity. Delicate septa divided the parenchyma into small feebly denned lobules. Electron microscopy revealed that the parenchyma comprised type I cells, type II cells, nerve endings, axons and fenestrated dilated capillaries. Type I cells were characterized with electron dense-cored vesicles. They showed variations in size and concentration of the dense-cored vesicles and number of mitochondria. The possibility that these variations are reflections of different stages of activity is discussed. Type II cells were less numerous than type I cells, relatively small and devoid of dense-cored vesicles. They usually surrounded small groups of type I cells and associated nerve endings and axons. Presumptive afferent nerve endings characterized with many clear vesicles, occasional large granular vesicles and varying numbers of slender mitochondria, lay apposed to type I cells. Nerve endings of this kind showed afferent and efferent synaptic junctions with type I cells. Presumptive sympathetic efferent endings were occasionally seen within the lobules but never lay apposed to type I cells or afferent nerve ending. 相似文献
12.
本研究以西藏自治区班戈县的典型高寒草原为研究对象,设置田间小区控制试验,于2013-2015年施加不同数量氮磷肥(N: 0、7.5、15.0 g N·m -2, P: 0、7.5、15.0、30.0 g P 2O 5·m -2), 调查各处理不同类群植物生物量、分析土壤理化性质,进而评价氮磷养分添加对高寒草原草地质量和土壤环境质量的影响。试验结果表明:1)氮磷配施优于氮磷肥单施,不同氮磷配施处理均能提高草地质量指数(IGQ),以N 1P 1(7.5 g N·m -2, 7.5 g P 2O 5·m -2)施肥处理的草地质量指数最大(90.27),相较对照增加了67.16%(P<0.05)。2)选择土壤有机质(OM),全氮(TN)、全磷(TP)、有效氮(AN)、有效磷(AP)和pH作为土壤环境质量评价指标, 应用主成分分析法对不同土层(0~10 cm、10~20 cm、20~30 cm) 12个施肥处理的土壤理化性质进行分析。结果表明,短期施肥主要影响土壤0~10 cm土层环境质量的变化;增施氮肥土壤pH呈下降趋势;高磷添加处理(30.0 g P 2O 5·m -2)增加了土壤全磷、有效磷含量,但植物吸收效率下降。3)结合草地质量指数和土壤理化性质变化进行草地质量综合评价,结果表明氮磷肥配施好于单施,且N 1P 1(7.5 g N·m -2,7.5 g P 2O 5·m -2)处理相对得分最高,为本试验条件下的适宜施肥量。 相似文献
13.
1. Fifteen ostrich females were monitored for a full breeding season. At 30, 70, 110, 150 and 210 d from the beginning of laying, one egg per female was taken to the laboratory to assess its physical and nutritive characteristics. 2. The average length was 15.4 cm, while the width was 12.9 cm. Average shell thickness ranged from 2.20 mm at the equator to 2.24 mm at the small pole. The three principal components of the egg (albumen, yolk and shell) amounted to 57.1, 23.3 and 19.6%, respectively. None of the above variables, despite showing some significant differences between sampling periods, showed a clear trend linked to the laying season. 3. In contrast, the dry matter of the albumen showed a correlation with the sampling period, increasing from 11-1% in the first period to 12.0% in the last. The crude protein content ranged from 47.7 to 48.2%, the fat from 43.8 to 44.2% and the ash between 5.2 and 5.5% of dry matter. 4. The fatty acid composition of the yolk showed the presence of C18:1 (from 122.0 to 136.4 mg/g), followed by C16:0 (from 40.8 to 46.0 mg/g), C18:0 (from 19.2 to 21.2 mg/g) and C18:2 (from 17.1 to 19.6 mg/g). The content of cholesterol/g of yolk was between 10.6 and 10.9 mg. 5. In conclusion, compared with the hen's egg, the ostrich egg has similar chemical and nutritive characteristics, but a higher unsaturated/saturated fatty acid ratio and lower cholesterol content. 相似文献
14.
对山西暖性灌草丛、暖性草丛、温性草原和温性山地草甸4种主要类型草地土壤0~5cm、5~10cm、10~20cm、20~30cm、30~50cm、50~70cm和70~100cm不同垂直剖面有机碳密度及碳储量的分配特征进行研究,结果表明:山西4种主要草地土壤有机碳含量在107.98~145.62g/kg之间,平均为131.42g/kg。土壤有机碳密度平均为6.78kg/m^2,暖性草丛类最高,为7.25kg/m^2,其次为暖性灌草丛类和温性草原类,温性山地草甸类最小,为6.32kg/m^2。4种主要类型草地土壤有机碳表聚性明显,表层土壤有机碳占总有机碳的比例分别为52.85%、49.12%、46.79%和50.36%。随土层深度的增加,土壤有机碳含量逐渐降低,但不同类型草地减少的程度不同。草地土壤有机碳密度随土层深度的增加逐渐增大,暖性类草地0~100cm土层平均土壤碳密度均高于温性类草地。4种主要草地土壤总碳储量为257.39Tg。 相似文献
15.
Fifteen conventional 8-week-old pigs were used to compare the morphology and function of Peyer's patches (PP) in different parts of the small intestine with special emphasis on the dome epithelium (DE). The comparisons were done by morphological observation through light and electron microscopy, and by the ability of the DE complex to phagocytize horseradish peroxidase (HRP). Dome epithelium of the PP in the jejunum was more superficially located in the mucosa in comparison with the ileum. The DE's of the ileum were much smaller, with an area of 3.7 micron2/DE, than that of the jejunum (18.4 micron2/DE). The number of DE areas/5 cm2 in the ileum was more than in the jejunum. However, the total surface area of DE/5 cm2 of PP, was larger in the jejunum (180.5 micron2) than in the ileum (55.6 micron2). Brown discoloration of diaminobenzidine-hydrogenperoxide (DAB+H2O2)-treated PP specimens, after HRP inoculation, intensified with post-inoculation time from 20 s to 5 min. The brown pigment first appeared on the surface of microvilli and infiltrated into the dome. No morphological differences were observed between the jejunum and the ileum in 1 micron thick Epon-embedded specimens. Intramucosally, brown pigment was almost always found in DE areas. The pigmented areas were more numerous in the jejunum but the color intensity showed no obvious difference. By transmission electron microscopy, the electron dense materials (which were interpreted as the products of HRP and DAB+H2O2) were found between the microvilli of membraneous (M) cells, in the intercellular spaces of the DE, and in a form similar to intracytoplasmic vesicles in the cytoplasm of M-cell and DE complex lymphocytes. Our results confirmed that DE of PP had much stronger phagocytic activity than did the ordinary villous epithelium. This evidence indicates that the DE complex of PP in the swine intestine is immunologically important. 相似文献
16.
通过测定土壤容重、土壤有机碳含量和土壤酶活性,探讨了不同种植年限(1,3,4,5和8年)紫花苜蓿人工草地剖面土壤有机碳含量、土壤碳密度及土壤酶活性的垂直分布差异。结果表明,1)1~8年0~100 cm土壤平均SOC含量分别为4.519,4.865,5.120,5.348和3.334 g/kg,各土壤剖面SOC含量主要集中在0~40 cm深度内,分别占0~100 cm土壤有机碳含量的69.7%,65.8%,73.8%,70.0%和67.2%,SOC含量自40 cm以下急剧下降。2) 1~8年0~100 cm土壤平均SOC密度分别为1.148,1.217,1.231,1.398和0.840 kg/m 2,表层0~40 cm约占54.8%~61.8%;0~100 cm SOC含量及其密度均以种植5年苜蓿地最高,依次为8年(19.9 g/kg和5.04 kg/m 2)<1年(27.7 g/kg和6.77 kg/m 2)<3年(29.7 g/kg和7.26 kg/m 2)<4年(30.4 g/kg和7.38 kg/m 2)<5年(32.2 g/kg和8.53 kg/m 2)。3)3种土壤酶活性都随着土层加深和种植年限的增加而降低,土壤表层(0~10 cm)及次表层(10~20 cm)酶活性显著降低,土壤酶活性主要集中在0~20 cm深度内,表现出表聚性。 相似文献
17.
The effect of a low‐Mn diet on egg shells was assessed by recording the number of soft shells laid at the beginning of lay, and the shell thickness of subsequent eggs. Observations were made on eggs from two batches of pullets: one that had been fed the low‐Mn diet from 1 month before egg laying began and the other from 2 months before onset of lay. The 2 month period gave fewer soft shells but thinner firm shells than the 1‐month period. Similar observations were made with groups having mean pre‐laying periods on the low‐Mn diet of 46, 33, 21 and o d. There was a tendency for more soft shells and thinner shells to be produced the longer the period of low‐Mn feeding before laying began. Pullets that had been in lay for 6 months or low‐ or high‐Mn diets were given an enforced rest period for 6 weeks. On recommencing to lay the low‐Mn birds produced a large number of soft shells and slightly thinner shells than similar birds that had been allowed to continue laying on the same diet. 相似文献
18.
1. Eighteen diets supplying all combinations of three phosphorus contents (3.1, 4.0 and 4.8 g non‐phytate P/kg) and six vitamin D supplements (37.5 or 150 μg cholecalciferol/kg; or 16 or 24 μg 25‐hydroxy‐cholecalciferol/kg; or 37.5 μg cholecalciferol/kg with either 16 or 24 μg 25‐hydroxycholecalciferol/kg) were fed to 2 880 pullets of two stocks from 64 to 74 weeks of age. The birds were housed in eight light‐proof rooms, four of which had 24‐h light‐dark cycles (16L : 8D) and four had 28‐h cycles (20L : 8D). 2. The dietary treatments had no significant effect upon food intake, egg output, shell thickness, shell deformation or specific gravity of the eggs. 3. The 28‐h cycle reduced mean rate of lay by 4.5%, increased egg weight by 5.8% and increased shell thickness by 9.4%. The proportion of eggs with shell faults revealed on candling was reduced from 4.1 % to 2.8%. 4. It is concluded from this and other sources that decreasing dietary phosphorus or modifying vitamin D supplements may sometimes lead to increases in shell thickness of the order of 1 to 2%, but that these changes are unlikely to result in a measurable reduction in the proportion of cracked eggs late in the laying year. 5. A 28‐h light‐dark cycle results in a longer and more uniform interval between consecutive ovipositions and thus gives reliable increases in shell thickness which are large enough to reduce the proportion of cracked eggs in many practical situations. Whether it is profitable to use an ahemeral cycle will depend upon the relative prices paid for eggs of different sizes. 相似文献
19.
Food and calcium intake and egg shell strength were measured for 24 d with 40 laying hens fed on a daily ration of either 120 g of an all‐mash diet containing 3.25% Ca or 111 g of a 0.6% Ca diet plus 8.7 g of oyster shell. The additional calcium source was offered for a 3¼‐h period beginning at 09.00, 14.00 or 17.15 h. Consumption of oyster shell was lowest in the morning. When the calcium meal was offered at this time, the hens slightly increased their calcium ingestion on oviposition days. However, calcium intake was higher on ovulation days when oyster shell was offered after 14 h. In each case, actual requirements seemed to be one of the main factors for determining calcium appetite. Variations of food intake in relation to laying cycle were evident with the control diet but disappeared when oyster shell was offered separately in the afternoon. Consumption of low Ca diet was greater than that of control diet only when oyster shell was given in the late afternoon of days without ovulation. The best egg shell quality was obtained by offering oyster shell between 14.00 h and 17.15 h but the difference with control was rarely significant. Practically it is recommended that oyster shell is given at least 3 h before light extinction. 相似文献
20.
Age related changes and osteochondrosis in swine were studied using light microscopy and electron microscopy in articular cartilage and light microscopy and epiphyseal cartilage of swine from three days to 30 weeks of age. Thickness, cellularity and vascularity of both the epiphyseal and articular cartilage, decreased as the swine aged. Osteochondrotic changes included formation of "plugs" of cartilage indicating localized failure of ossification and separation and space formation in epiphyseal cartilage. Eosinophilic streaks and space formation in epiphyseal cartilage was observed in relation to epiphyseal separation. Electron microscopy showed a continuous fibrillar layer on the surface of the cartilage corresponding to the lamina splendens of light microscopy. This layer increased in the thickness and showed accumulation of amorphous material between the fibrils with aging. In the matrix, the orientation and distribution of the collagen fibers changed with growth and thicker fibers with clear sub banding were more common in older age groups. Also, necrotic cells, glycogen containing bodies and cellular debris were noticed in the matrix of normal cartilage in old animals. Chondrocytes in the younger cartilage showed accumulation of organelles responsible for protein synthesis; while Golgi bodies, vesicles, lysosomes, well developed foot processes and other inclusions were noticed in older cartilage. Cartilage erosions had a clumped and disrupted lamina splendens on the surface and electron lucent patches in the ground substances of the matrix and chondrocyte cytoplasm. 相似文献
|
下载免费PDF全文