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1.
1. Seventy Hubbard hens, 75 weeks of age, were divided into groups containing equal numbers of hens on the basis of duration of fertility. Average fertile periods were 14.5 d (long, L) and 6.9 d (short, S). Each hen was artificially inseminated (AI) on three consecutive days with an average of 1.61 X 10(9)/0.05 ml spermatozoa per insemination. Seven hens from each group were killed 1, 3, 6, 9, and 13 d after insemination. 2. Three longitudinal sections of uterovaginal junction were evaluated microscopically for spermatozoal storage capacity by assigning each sperm host gland (SHG) to one of 5 categories: unscorable, empty, one to 5 spermatozoa, 6 to 20 spermatozoa and greater than 20 spermatozoa. 3. The only significant difference in sperm storage at any time between the L and S duration groups occurred at day 1 after AI, when L duration hens possessed significantly more glands with more than 20 spermatozoa. 4. One day after AI the proportion of SHG containing sperm were 28.8% (L group) and 18.6% (S group). There was a significant decrease in the number of glands containing 1 to 5, 6 to 20 and greater than 20 spermatozoa between days 1 to 3 in both groups. 5. Numbers of glands in all categories containing sperm decreased throughout the 13-d period. The L duration group possessed 18.5% more glands with 1 to 5, 6 to 20 and greater than 20 spermatozoa than the S duration group. 6. There were no significant differences between groups in the proportion of unscorable or empty glands throughout, which ranged from 35.9 to 56.8% and 36.3 to 47.1%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

2.
本试验旨在研究饲粮中添加大豆磷脂(SL)对产蛋鸡生产性能和鸡蛋磷脂含量的影响.选用360只22周龄健康产蛋鸡,随机分为5个处理,每个处理6个重复,每个重复12只鸡.5种试验饲粮中分别添加0、0.5%、1.0%、2.0%和4.0%的SL.试验期4周.试验结果表明:1)0.5%SL组平均蛋重最大(P>0.05),1.0%SL组平均日采食量最低(P>0.05),1.0%和2.0%SL组的料蛋比较低(P>0.05),均显著低于对照组(P<0.05),产蛋率以0.5%组最高(P>0.05),即饲粮中添加0.5%～2.0%的SL可改善产蛋鸡的生产性能;2)饲粮添加SL可以降低鸡蛋蛋黄水分含量(约1.7个百分点)(P>0.05)、1.0%、2.0%和4.0%SL组的蛋黄粗脂肪含量显著高于对照组(P<0.05);1.0%、2.0%和4.0%SL组全蛋中总磷脂显著高于对照组(P<0.05),1.0%和2.0%SL组蛋黄中总磷脂含量显著高于对照组(P<0.05),同时蛋黄胆固醇含量略有增加(P>0.05);1.0%、2.0%和4.0%SL组蛋黄和全蛋中磷脂酰胆碱(PC)含量显著高于对照组(P<0.05);2.0%SL组磷脂酰乙醇胺(PE)最高,但各组间差异不显著(P>0.05);PC/PE随饲粮SL添加量的增加而线性升高,0.5%、1.0%和2.0%SL组均显著高于对照组(P<0.05),4.0%SL组显著高于其他组(P<0.05).结果提示,饲粮添加一定水平的SL可改善产蛋鸡的生产性能,提高鸡蛋中总磷脂和PC含量.  相似文献   

3.
1. Daily injection of hypothalameal extract (HE) and adenohypophyseal extract (AE) into hens aged 56 or 67 weeks for 14 d did not significantly influence the production of shell-less (SL) or ultra-thin-shell (UTS) eggs. 2. The injection of HE significantly increased hard-shell (HS) egg production in the younger hens. 3. Neither AE nor HE affected egg weight, serum calcium, gain in body weight or food consumption. 4. In a third experiment hens selected for poor egg production laid at a rate of 58% of which 36% were SL, 29% UTS and 35% HS eggs. Whereas the production rate of the good layers was 65% of which 1-4% were SL and 1-4% were UTS eggs. 5. Specific gravity of HS eggs, serum calcium, weight of ovary, oviduct, or adenohypophysis did not differ between good and poor layers. 6. Since SL and UTS eggs are easily overlooked the decrease in egg production with age may be as great as indicated by normal production records; the problem may be concerned more with the mechanism of shell formation.  相似文献   

4.
The goal of our present study was to observe whether the populations of antigen presenting cells (Ia+ cells) and T cell subsets (CD4+ and CD8+ T cells) change in the utero-vaginal junction (UVJ) of Rhode Island Red laying hens that showed dramatic declines in fertility after repeated artificial insemination (AI). Rhode Island Red laying hens were divided into two groups: a virgin group (R-V) and artificial inseminated group (R-AI), which was exposed to weekly AI for a period of 3 mo. Undiluted fresh semen collected from healthy Tosa-Jidori roosters, a native Japanese breed maintained in Kochi Prefecture, was used for AI. The UVJ tissues were processed for frozen sections, and Ia+ cells and CD4+ and CD8+ T cells were identified by immunohistochemistry. The Ia+ cells and CD4+ and CD8+ T cells were observed in the stroma and mucosal epithelium of UVJ in both the R-AI and R-V birds. The frequencies of them in the stroma were significantly higher in R-AI than R-V. The higher frequency of Ia+ cells in the UVJ of R-AI group indicated a greater potential capability for antigen presentation to CD4+ cells. The significant increase in CD8+ and CD4+ T cells in the UVJ of R-AI birds might be the result of a homing process of lymphocytes, which may affect sperm survivability and fertility.  相似文献   

5.
This study was conducted to compare the efficacy of diet supplemented with non-microencapsulated lutein (NL) and microencapsulated lutein (ML) in laying hens. A total of 270 Hy-line Brown laying hens (54 weeks old) were allocated to three groups with six replicates of 15 hens and were adapted to a wheat-soybean meal basal diet for two weeks. Next, the control birds were fed the basal diet, and the test birds were fed the basal diet supplemented with 600 mg/kg NL (12 mg/kg available lutein) or 90.1 mg/kg ML (10 mg/kg available lutein) for 35 days. Supplementation of lutein did not affect the productive performance of laying hens, but improved (P<0.05) the yolk color and red/green value (a*), with eggs from the ML group displaying improved color and a* values from the 15th day of the experimental period. The blue/yellow value (b*) for the yolk showed an increase (P<0.05) through both NL and ML supplements. The yolk color of fried and boiled eggs and a* value of the yolk in fried eggs were improved (P<0.05) only through ML supplemented diet. Both NL and ML supplements resulted in lower (P<0.05) lightness and higher (P<0.05) a* values of yolk in boiled eggs, as well as higher (P<0.05) b* values in fried and boiled eggs. Yolk lutein content in fresh, fried, and boiled eggs was increased (P<0.05) in NL and ML groups with the latter being higher. In conclusion, ML improved yolk pigmentation and lutein retention in laying hens better than NL.  相似文献   

6.
旨在探究不同贮精能力母鸡的贮精腺形态、主要性激素水平以及激素受体基因表达量的差异,以期进一步揭示母鸡贮精能力差异产生的原因。本研究以27周龄158只的白来航母鸡和28只公鸡为试验材料,混精连续输精2 d,第3天开始按照个体收集种蛋孵化,根据输精后21 d内每天的种蛋受精情况统计个体受精率作为母鸡贮精能力;挑选高、低贮精能力极端个体各4只,分别为高、低贮精能力组;采血测定血清孕酮、雌激素、睾酮和催乳素激素浓度;解剖获取富含贮精腺的子宫阴道连接部组织,并沿纵向分为两份,一份制作石蜡切片并HE染色,用于贮精腺形态观察,另一份采用荧光定量PCR检测相应激素受体基因的表达量。结果表明,高、低贮精能力组子宫阴道连接部的黏膜面积、贮精腺数量、贮精腺密度均差异不显著（P>0.05）,但高贮精能力组母鸡的贮精腺平均横截面积显著高于低贮精能力组（P<0.05）;高贮精能力组母鸡的血清孕酮激素浓度显著高于低贮精能力组（P<0.05）,雌激素、睾酮和催乳素激素浓度在组间均差异不显著（P > 0.05）;与低贮精能力组相比,高贮精能力组睾酮受体基因和催乳素受体基因表达上调,雌激素α、β受体基因和孕酮受体基因下调,但未达显著水平（P>0.05）。结果提示,母鸡的贮精能力可能与贮精腺横截面积有关,此外,孕酮激素可能对诱导贮精腺中精子的激活起重要作用,从而影响母鸡持续受精能力。  相似文献   

7.
本研究旨在了解褪黑激素受体基因MTNR1B的多态性及其与文昌鸡产蛋性状的关系。用直接测序的方法检测MTNR1B5′调控区、外显子1和外显子2的单核苷酸多态性,并将其与文昌鸡的产蛋性状进行关联分析。结果表明,在外显子1和2的编码区未发现碱基突变或缺失,而在5′调控区发现15个单核苷酸多态位点。其中-778位点突变(A→G)对文昌鸡中期(22～31周龄)产蛋数和46周龄总产蛋数的显性效应分别达到了2.3和6.2枚(P<0.05)。对后期(32～46周龄)产蛋数和46周龄总产蛋数而言,-216位点C对A为优势等位基因,加性效应值分别为2.5和3.2枚,显性效应分别为3.5和6.8枚,且表现为超显性。在4种单倍型中,AA单倍型个体的后期产蛋数和46周龄总产蛋数最低,GC单倍型个体的开产日龄最早。AC/GA联合基因型母鸡拥有最高的中期产蛋数、后期产蛋数和46周龄总产蛋数。综上所述,MTNR1B基因的外显子高度保守,而5′调控区的SNPs有望成为影响产蛋性状潜在的遗传标记。  相似文献   

8.
试验旨在比较洪江雪峰乌骨鸡和罗曼粉蛋鸡的鸡蛋营养成分和蛋品质,为洪江雪峰乌骨鸡蛋用新品系选育提供依据。随机选取40周龄的洪江雪峰乌骨鸡(绿壳)、洪江雪峰乌骨鸡(粉壳)和罗曼粉壳蛋鸡各100只,每品种鸡随机分为5个重复,每个重复20只,在相同饲粮和饲养管理方式下进行饲养,45周龄收集鸡蛋检测营养成分和蛋品质指标。结果表明:洪江雪峰乌骨鸡绿壳蛋的蛋黄比例极显著高于罗曼粉壳蛋(P<0.01),蛋重、蛋壳厚度、哈氏单位极显著低于罗曼粉壳蛋(P<0.01),洪江雪峰乌骨鸡粉壳蛋的蛋重和蛋壳厚度极显著低于罗曼粉壳蛋(P<0.01);洪江雪峰乌骨鸡蛋中的多不饱和脂肪酸和硒元素含量均极显著高于罗曼粉壳蛋(P<0.01),洪江雪峰乌骨鸡绿壳蛋胶原蛋白含量极显著高于罗曼粉壳蛋(P<0.01)。综上所述,洪江雪峰乌骨鸡鸡蛋蛋黄比例高,蛋黄多不饱和脂肪酸、胶原蛋白、硒和锰含量高,适合作为优质禽蛋开发。  相似文献   

9.
1. Saline drinking water given to pullets before sexual maturity had no effect on their subsequent egg shell quality. 2. Hens receiving saline drinking water from or after laying their first egg produced significantly more egg shell defects than hens receiving town water. 3. The production of eggs with defective shells occurred more rapidly when saline drinking water was given to 40-week-old hens than to hens during the first few weeks of lay. 4. The high incidence of egg shell defects resulting from the use of saline drinking water was reduced to control levels when hens in early lay were given town water for 5 weeks. This response was not observed with 40-week-old hens.  相似文献   

10.
Eggs from young turkey breeder hens have a higher rate of early embryonic mortality (EEM) than eggs from older hens. Preliminary field data indicated that increased sperm concentration decreased the incidence of EEM in eggs from young hens. Possible explanations for decreased EEM following insemination with more concentrated sperm may include altered sperm binding and hydrolyzing of the inner perivitelline layer (IPVL) of eggs from hens of different ages. The current study examined differences in the number of sperm penetration (SP) holes hydrolyzed in the IPVL in hens at 2 different ages when inseminated with 25, 50, 100, 200, 400, or 800 million viable sperm. Hens (12/treatment) were inseminated on d 14 and 21 after photostimulation (32 and 33 wk of age) and were inseminated again at 12 and 13 wk of egg production (44 and 45 wk of age). The SP holes hydrolyzed in the IPVL were counted in the 1,098 eggs produced in the 3 wk following each insemination period. The number of SP holes hydrolyzed in the IPVL was significantly (P ≤ 0.05) greater in younger hens than older hens. Furthermore, the number of SP holes was significantly greater (P ≤ 0.01) with the 400 and 800 million insemination doses as compared with the other 4 insemination doses. There was no interaction between hen age and sperm insemination dose. In conclusion, the absence of an interaction between hen age and insemination dose suggests that factors other than numbers of sperm binding to the IPVL influence EEM. These factors may be a combination of oviduct influences and IPVL properties that change as the hen ages.  相似文献   

11.
Upon contact with laid eggs, avians initiate incubation behavior and stop laying additional eggs. This phenomenon suggests that the productivity of laying hens in free-range facilities may decrease because of frequent contact with laid eggs. Here, we examined whether hens of a commercial breed exhibit incubation behavior in a free-range facility and whether egg productivity subsequently decreases. One-hour observations were performed twice weekly for 3 weeks, during which 9 of 129 hens (7.0%) exhibited incubation behavior (i.e., sitting on eggs) in the free-range facility and were defined as incubating hens. During 4 d of continuous behavioral observation, incubating and non-incubating hens laid the same number of eggs statistically (4.6 and 3.6, on average, respectively); however, incubating hens spent significantly more time on average incubating the eggs (2071.9 min) than did the non-incubating hens (20.9 min; P<0.05), indicating a clear behavioral difference. Subsequently, the incubation behavior and egg productivity of incubating hens and a Silkie Fowl breed hen, which is known to exhibit typical incubation behavior and cessation of laying, were continuously compared for 27 d. The average minutes spent incubating eggs during the observation period increased in both the incubating hens and Silkie Fowl hen and the total time was almost the same (18,088.5 and 23,092 min, respectively). However, the Silkie Fowl hen stopped laying on day 17 after laying 17 eggs, whereas the incubating hens continued laying throughout the observation period. Incubating hens laid an average of 24.5 eggs, indicating that some hens (at least those of the commercial breed used in our study) can continue laying while exhibiting incubation behavior. A single-nucleotide polymorphism associated with incubation behavior was detected on chromosome 4 through genome-wide association analysis.  相似文献   

12.
The time-course of the changes in blood ionized calcium, and in plasma 1,25 dihydroxycholecalciferol (1,25(OH)2D3) concentrations and its free index were studied in hens following suppression and resumption of shell formation and throughout the laying cycle in hens laying hard-shelled eggs, in hens fed a low or normal calcium diet and in hens laying shell-less eggs. The respective roles of the calcium needs for shell formation and of the reproductive status in regulation of 1,25(OH)2D3 production were analysed. Plasma 1,25(OH)2D3 decreased 3 hr after suppression of shell formation following premature egg expulsion and remained lower than that of hens laying hard-shelled eggs when premature expulsion of the eggs was continued for several days. Circulating 1,25(OH)2D3 tended to increase progressively when shell formation was resumed. Ablation of the parathyroid glands abolished this increase. In hens laying hard-shelled eggs, the plasma 1,25(OH)2D3 was higher during the period of shell secretion. Feeding hens a low calcium diet (1.2%) caused a marked increase in the plasma 1,25(OH)2D3. Ionized calcium levels tended to show reciprocal changes to plasma 1,25(OH)2D3 decreasing when calcification took place and increasing after its suppression. In hypercalcemic hens laying shell-less eggs and fed a 3.5% Ca diet, the plasma 1,25(OH)2D3 was at a high level 4 hr after ovulation and diminished thereafter. This additive stimulation does not, therefore, involve the parathyroid gland and may involve hormonal changes induced by ovulation. Vitamin D binding protein (DBP) in the plasma was at a high level in mature hens and was not affected by shell formation. Consequently, the free 1,25(OH)2D3 index fluctuated in parallel with total level of this hormone in mature hens. It is concluded that the calcium demand for shell formation modulates, in the short term, plasma 1,25(OH)2D3, via the homeostatic regulation of blood calcium by PTH, but that a large part of its increase is independent of PTH and is associated with the endocrine events concomitant with ovulation.  相似文献   

13.
The purpose of this study was to evaluate feeding 2 levels of spray-dried bovine plasma protein (SDP) on production performance of laying hens subjected to high ambient temperatures. Two groups of 96 Hy-Line W-98 hens (38 wk of age) were housed in each of 2 environmentally controlled chambers. At 40 wk of age, all hens were fed 3 diet treatments consisting of (1) a control diet (0% SDP); (2) the control diet supplemented with 0.75% SDP; and (3) the control diet supplemented with 1.50% SDP. Hens in each chamber (8 cages of 4 hens per cage) were ad libitum fed 1 of each diet for 5 wk. The heat stress (HS) chamber was maintained at 21°C (wk 1), 29°C (wk 2), and 35°C (wk 3 to 5). The thermoneutral chamber was maintained at 21°C during wk 1 to 5. A significant main effect of week was observed for hens maintained in the HS chamber for egg production, egg weight, egg mass, and feed consumption, which resulted in acute heat stress causing a reduction in these parameters. Hens fed the 1.50% SDP diet in the HS chamber produced greater (P < 0.05) egg mass on average than hens fed the control or 0.75% SDP diet (wk 1 to 5). During the second week of acute HS (wk 4), hens fed the control and 1.50% SDP diets had greater (P < 0.05) egg production than those fed the 0.75% SDP diet. During wk 5, hens in the HS chamber that were fed the 1.50% SDP diet produced more (P < 0.05) eggs than those fed the control diet. Therefore, based on the results of this study, acute HS negatively affected short-term production performance. In addition, feeding hens an SDP-supplemented diet may have a slight positive effect on production performance when maintained in acute HS conditions.  相似文献   

14.
旨在利用从藏灵菇中筛选的可显著降低血清胆固醇和耐受胃肠道逆环境的副干酪乳杆菌KL1菌株制备微生态制剂,探讨该制剂在低胆固醇鸡蛋生产中对蛋鸡生产性能、蛋品质及鸡蛋中胆固醇含量的影响。本试验将120只30周龄健康状态良好且产蛋率接近的农大3号矮小蛋鸡随机分为低、中、高剂量试验组和对照组,每组5个重复,每个重复6只蛋鸡,试验组在基础饲粮中分别添加105、106、107 CFU·（只·d）-1副干酪乳杆菌KL1微生态制剂,对照组饲喂基础饲粮,连续饲喂10周。对蛋鸡的生产性能、蛋品质和鸡蛋中的胆固醇进行测定和计算。结果表明：1）中剂量组的蛋鸡饲养日产蛋率与对照组相比有显著提高（P<0.05）;2）与对照组相比,中、高剂量组的蛋壳强度、蛋壳厚度和血清钙水平有显著提高（P<0.05）,蛋黄相对重有极显著提高（P<0.01）;3）低、中、高剂量组的蛋黄胆固醇含量及血清总胆固醇（TC）、甘油三酯（TG）含量均极显著低于对照组（P<0.01）;高剂量组的血清高密度脂蛋白胆固醇（HDL-C）和低密度脂蛋白胆固醇（LDL-C）含量分别极显著高于对照组（P<0.01）和显著低于对照组（P<0.05）。在饲粮中添加副干酪乳杆菌KL1微生态制剂可显著提高蛋鸡生产能力和蛋壳品质,降低鸡蛋中胆固醇含量,总体来看,以106 CFU·（只·d）-1作为最终添加剂量效果最佳,在低胆固醇鸡蛋的生产中具有良好的应用价值。  相似文献   

15.
试验旨在探究天然腐植酸和合成腐植酸对蛋鸡产蛋后期生产性能、蛋品质、血清生化指标、抗氧化指标和激素水平的影响。选取52周龄体重、产蛋率相近的海兰白蛋鸡405羽,随机分成3个组,每组9个重复,每个重复15羽。对照组饲喂基础饲粮(CON组),试验组在基础饲粮中分别添加1 000 mg/kg的天然腐植酸A(HAA组)和合成腐植酸B(HAB组),预试期2周,正试期8周。结果表明:与CON组相比,添加腐植酸均可提高平均蛋重(P<0.05),降低不合格蛋率(P<0.05)和料蛋比(P<0.01),其中HAA组产蛋率极显著提高,HAA组的料蛋比低于HAB组(P<0.01);饲粮添加腐植酸对蛋品质无显著影响;与CON组相比,HAA组血清中白蛋白含量降低(P<0.05),HAB组乳酸脱氢酶活性提高(P<0.05),HAA组与HAB组血清中甘油三酯含量均降低(P<0.01);相比于CON组,添加HAB可提高谷胱甘肽过氧化物酶活性(P<0.05);与CON组相比,饲粮中添加腐植酸提高了血清中促黄体素水平(P<0.01),对促卵泡素水平有升高趋势(P=0.060),且HAA组中促卵泡素水平高于HAB组(P<0.01)。结果提示,腐植酸可促进机体促性腺激素分泌,改善机体抗氧化水平,显著提高产蛋后期蛋鸡的生产性能,且天然提取的腐植酸作用效果更佳。  相似文献   

16.
旨在探讨日粮中铁和VA对商品代海兰褐蛋鸡血清蛋白代谢的影响。选用26周龄健康育成母鸡432只,随机分成6组,每组6个重复,采用3×2（铁×VA）完全随机试验设计方法,日粮中铁的添加量分别为0、30、60mg／kg,VA的添加量为4000、8000IU／kg。从27周龄开始进行正试期为8周的饲养试验,分别于30周龄和34周龄时测定蛋鸡血清总蛋白含量和血清尿素氮含量。结果表明,日粮铁和VA交互作用对30周龄和34周龄蛋鸡的血清总蛋白浓度影响不显著（P〉0．05）;日粮VA的添加水平对30周龄蛋鸡血清总蛋白浓度影响显著（P〈0．05）,并且高水平VA添加组（8000IU／kg）显著高于低水平VA添加组（4000IU／kg）。日粮铁和VA交互作用对30周龄和34周龄蛋鸡的血清尿素氮浓度影响不显著（P〉0．05）;日粮VA的添加水平对30周龄蛋鸡的血清尿素氮浓度影响极显著（P〈0．01）,并且高水平VA添加组（8000IU／kg）显著低于低水平VA添加组（4000IU／kg）。综上提示,日粮中添加VA能够改善蛋鸡的蛋白代谢过程。  相似文献   

17.

  1. A total 120 laying hens (60 TETRA BLANCA white egg layers and 60 TETRA SL brown egg layers) were selected from 250 TETRA BLANCA and 250 TETRA SL pullets based on their predicted body fat content by means of computed tomography (CT) at 16 weeks of age. Three groups of pullets were chosen for the investigation with the highest (n = 20), lowest (n = 20) and average (n = 20) body fat content.

  2. Changes in the live weight, body fat content, egg production and egg composition of the chosen animals were recorded at 32, 52 and 72 weeks of age.

  3. Based on the results, it was established that differences in starting body fat content of the hens remained the same during the experimental period. The differences between the two extreme groups were statistically significant at each age.

  4. The starting body fat content of the hens affected the rate of egg production, i.e. hens with high starting body fat content produced 11–14 eggs fewer than the hens with a low or average body fat content but had no effect on the composition of the eggs.

  5. Genotype affected almost all of the examined traits: TETRA BLANCA hens had lower live weight and higher body fat content during the experimental period and produced fewer eggs with lower albumen and higher yolk, dry matter and crude fat content than the TETRA SL hens.

  相似文献   

18.
In China, consumers sometimes get special eggs, which are characterized by the pasty, firm, and elastic texture of yolk from hard-boiled eggs and are usually called “rubber eggs” by Chinese customers. Consumers do not like the texture of rubber eggs and often associate the odd texture of the yolk to food safety risks. The objective of this study was to assess the physical and chemical characteristics of these eggs. A total of 200 46-week-old Hy-Line Brown laying hens were divided into 2 groups and were fed for 2 weeks. One group was fed on a corn-soybean meal based diet (BD) and served as control whereas the second group’s diet contained 6% cottonseed meal (CSM), which was in replacement of the SBW. The yolks of hard-cooked eggs of the CSM group had harder and more elastic yolks than those of the control group (P < 0.05). Also, the levels of stearic and myristic acids in the yolk of the CSM group also were increased (P < 0.01), while the myristoleic, pentadecanoic, arachidic, cis-11-eicosenoic and cis-11, 14-eicosadienoic acids and crude protein, fat, phospholipids, chloride, calcium, and iron were decreased (P < 0.05). In conclusion, hens fed a diet that was incorporated with 6% cottonseed meal laid eggs that had unique physical and chemical characteristics and lower nutritional values. These results might help to guide limited incorporation of CSM in laying hen diet, and provide some evidences on the mechanism of the observed physical and chemical changes.  相似文献   

19.
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   

20.
As laying hens age, egg production and quality decreases. Egg producers can impose an induced molt on older hens that results in increased egg productivity and decreased hen mortality compared with non-molted hens of the same age. This review discusses the effect of induced molting by feed removal on immune parameters, Salmonella enterica serovar Enteritidis (SE) invasion and subsequent production of SE-contaminated eggs. Experimental oral infections with SE show molted hens are more susceptible to SE infection and produce more SE-contaminated eggs in the first few weeks post-molt compared with pre-molt egg production. In addition, it appears that molted hens are more likely to disseminate SE into their environment. Molted hens are more susceptible to SE infection by contact exposure to experimentally infected hens; thus, transmission of SE among molted hens could be more rapid than non-molted birds. Histological examination of the gastrointestinal tracts of molted SE-infected hens revealed more frequent and severe intestinal mucosal lesions compared with non-molted SE-infected hens. These data suggest that induced molting by feed deprivation alters the normal asymptomatic host-pathogen relationship. Published data suggest the highest proportion of SE-positive eggs is produced within 1-5 weeks post-molt and decreases sharply by 6-10 weeks and dissipates to the background level for non-molted hens by 11-20 weeks. Appropriate treatment measures of eggs produced in the fist 5 weeks post-molting may decrease the risk of foodborne infections to humans.  相似文献   

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