三种仿土鸡蛋的品质比较

本试验对矮小型麻羽蛋鸡、引进粉壳蛋鸡、青脚白羽鸡三个品种在地面平养方式下生产的仿土鸡蛋进行了品质比较,测定并分析了鸡蛋的几项物理性状。结果表明,矮小型蛋鸡所产的鸡蛋有较好的蛋品质。     

Influence of food restriction and of the presence of chicks on the reproductive system of the domestic hen

An experiment was conducted with 4 groups of hens: a control group of laying hens, a group subjected to food deprivation for 7 d, a group subjected to food deprivation for 7 d, then re-fed for 10 d and a group subjected to food deprivation for 7 d then re-fed for 10 d with two chicks per hen introduced during the last 7 d of refeeding. Food deprivation provoked the involution of the oviduct and ovarian regression, as well as a decrease in the plasma concentrations of luteinising hormone (LH) and sex steroids (progesterone, testosterone and oestradiol). After 3 d of re-feeding, there was a significant increase in the plasma concentrations of LH and steroid hormones. This phenomenon was even more marked after 10 d of re-feeding; most of the hens of the third group which were not given chicks, were at the point of lay. The presence of chicks resulted in the expression of maternal behaviour and suppressed a rapid return to laying. This was especially marked in hens showing typical maternal behaviour traits, for which the morphological and endocrine measurements indicated a decrease in the activity of the hypothalamo-hypophyseal-gonadal axis.     

光照周期和饲喂水平对蛋鸡生殖器官发育的影响

本试验旨在研究限饲和光照周期对蛋鸡卵巢和输卵管发育及形态学的影响。试验采用3×2双因子设计,即3个光照周期（8L：16D、12L：12D和16L：8D）和2个饲喂水平（自由采食和限饲鸡自由采食量的80%）。选用体质健康的10周龄海兰灰蛋鸡240只,分成6组,每组4个重复,每个重复10只鸡。结果表明,光照周期显著影响20 w输卵管重（P〈0.05）,长光照周期（16L：8D）组和中长光照周期（12L：12D）组的20 w输卵管重显著高于短光照周期（8L：16D）组,对卵巢卵泡直径及单位面积内卵巢卵泡个数影响不显著（P〉0.05）;饲喂水平对20 w体重、卵巢重、输卵管重及卵巢卵泡直径和单位面积内卵巢卵泡个数影响均不显著（P〉0.05）;光照周期和饲喂水平互作对20 w卵巢卵泡直径影响显著（P〉0.05）,其中,β和VI组卵巢卵泡直径显著高于V组（P〈0.05）,其他各组间差异不显著（P〉0.05）。饲喂水平、光照周期影响输卵管发育,Ⅱ、Ⅳ、VI自由采食组发育程度优于Ⅰ、Ⅲ、V限饲组,并且16L：8D光照组输卵管的发育状况最好。     

光照对马岗鹅季节性繁殖活动和内分泌的调控

研究了光照对马岗鹅季节性繁殖活动和内分泌的调控。在整个试验期（2004.01.13-12.18）对照组接受自然光照,处理组接受人工控制的长短光照处理。在非繁殖期（4-7月份）,对照组公母鹅血浆PRL浓度升高,LH浓度和公鹅睾酮水平降低,鹅换羽;在繁殖期（8-3月份）,公母鹅血浆PRL水平下降,LH浓度和公鹅睾酮水平则上升。在处理组,延长光照均使公母鹅PRL浓度升高,LH浓度和公鹅睾酮水平降低,鹅群进入休产期并换羽;缩短光照则降低PRL水平,促进LH分泌和公鹅睾酮水平上升,鹅群进入繁殖期。整个试验阶段,两组中公鹅甲状腺素T3水平均无明显季节性变化,处理组和对照组母鹅平均产蛋48.8和26.3枚,前者比后者高85.6%。试验结果表明,长光照抑制,短光照促进马岗鹅繁殖活动,光照通过调节PRL和LH的分泌调控马岗鹅繁殖活动的季节性变化。     

维生素A、维生素C和维生素E混合物对浙东白鹅繁殖机能的影响

研究了添加VA、VC和VE混合物(1.5 kg/t饲料)对浙东白鹅繁殖性能、血浆激素浓度和下丘脑-垂体-性腺轴基因mRNA水平的影响。结果显示:饲喂维生素混合物可显著提高浙东白鹅第1产蛋周期蛋重和受精率(P<0.05),但对第2产蛋周期产蛋量、蛋重、受精率和孵化率影响有限;饲喂维生素混合物可提高浙东白鹅第2产蛋周期内血浆FSH、P4、HCG和赖抱期、恢复期E2的浓度,降低LH浓度,改变浙东白鹅产蛋周期内FSH波动规律(P<0.05),降低下丘脑内PRLR、垂体内PRL和卵巢内PRLR基因的mRNA水平(P<0.05),提高卵巢内ESR2基因的mRNA水平(P<0.05),对下丘脑内GnRH、垂体内PRL和FSHβ、卵巢内PRL、ESR1和FSHR基因的mRNA水平影响不显著。因此,VA、VC和VE混合物可以通过影响繁殖期内部分血浆激素浓度变化,下调生殖轴PRLR mRNA水平以减弱PRL信号,从而改善浙东白鹅的繁殖性能。     

LH responses to chicken luteinizing hormone-releasing hormone I and II in laying,incubating, and out of lay turkey hens

An experiment was conducted to assess the relative in vivo and in vitro activities of chicken LH-RH-I and -II in laying, incubating and out-of-lay turkey hens. The highest plasma concentrations of LH were measured in laying turkey hens, whereas hypophyseal concentrations were highest in incubating hens (I) and lowest in the laying hens at the end of the laying period (EL). Hypophyseal and plasma concentrations of LH decreased with aging in laying hens (L) and the greater decrease occurred in the hypophyses. An in vitro hypophyseal acute challenge with 2-min pulses of cLHRH I or II (10⁻⁷ M) using a perifusion technique resulted in an increase in the release of LH in out-of-lay (OL) and incubating (I) hens, but not in laying (L) hens. Although both peptides elicited comparable responses in I hens, cLHRH II was more effective in OL hens. This difference was attributable to a greater amplitude of the response, whose duration was unchanged. Hypophyseal desensitization to a subsequent stimulation was observed in OL hens when the interval between stimulations was 30 min, but this did not occur at 60- or 120-min intervals. In vivo, the injection of cLHRH I or II, at doses of 10⁻⁸ and 10⁻¹⁰M/kg B.W. stimulated increases in the plasma concentrations of LH, which were initiated within 1 min of injection in OL and I hens but from 5 to 20 min postinjection in L hens. The responses were dose-related and greater immediate responses were measured with cLHRH I than with cLHRH II. Also, after the injection of cLHRH II at the 10⁻⁸ M/kg B.W. dose, the shape of the LH response consisted of an initial increase, followed by a more sustained phase during which LH concentrations were either stable (I hens) or continued to increase (L and OL hens) from 20 to 60 min after injection. In contrast, the injection of cLHRH I at doses of 10⁻⁸ or 10⁻¹⁰ M/kg or cLHRH II at a dose of 10⁻¹⁰ M/kg in I and OL hens, produced a peak of LH concentrations in plasma within 5 min and thereafter declined gradually. The difference in the in vivo responses to LHRH I and II could not be attributed to a greater potency of cLHRH II, but to a more prolonged action. In summary, the responses to both forms of chicken LH-RH varies markedly with the stage of the reproductive cycle (L, I, and OL) and differs between the in vivo and in vitro situations. Although cLHRH II may be more active than cLHRH I, controversy still surrounds its precise physiological role.     

Effect of age and body weight on plasma concentrations of luteinizing hormone in turkey hens before and after photostimulation

The independent effects of age and body weight (BW) on photostimulatory response in turkey breeder hens were studied by measuring changes in plasma luteinizing hormone (LH; ng/mL) before and 3 d after photostimulation. The study was conducted with hens from two BW groups at 24–25, 27–28, and 31–32 wk of age. There was approximately a 1-kg difference in BW between groups within an age. Six hens per BW and age group were cannulated (jugular vein) and serially sampled during each of two 6-hr periods. Samples were collected at 10-min intervals. The two sampling periods were the last 6 hr of the short-day photoperiod (SD) and the same period during the third long day after photostimulation (LD). The photostimulatory response (PR) or difference between the SD and LD baseline LH concentrations was greatest in the 24–25-wk-old hens. The PR was unaffected by hen BW at any age. The baseline LH concentration during the SD photoperiod declined as hens aged. After photostimulation, baseline LH and LH peak amplitude concentrations were higher in 24–25-wk-old hens compared with the older ages. The number of LH peaks increased after photostimulation, but there were no significant effects attributable to age or BW within an age. In conclusion, the PR was affected by hen age but not hen BW or BW within a particular age.     

Effects of photoperiod on broodiness,egg-laying and endocrine responses in native laying hens

1. The effects of photoperiod on broodiness, egg-laying and endocrine responses in native laying hens were investigated. A total of 648, 18-week-old native laying hens (Beijing You Chicken, BYC) were randomly allocated to 6 groups with 3 replicates. The birds were exposed to 1 of 6 different photoperiods, including 16L:8D (06:00 to 22:00 h) for group 1; 12L:2D:4L:6D for group 2; 8L:4D:4L:8D for group 3; 16L:8D (03:00 to 19:00 h) for group 4; 14L:10D for group 5; and 18L:6D for group 6.

2. The broodiness rate and egg-laying rate for weeks 20–26, 27–33, 34–40, 41–47, 48–54 and 55–61 were calculated, and serum prolactin (PRL), luteinising hormone (LH), 17-beta-oestradiol (E2), melatonin (Mel) and progesterone (P4) concentrations were measured at the end of each stage.

3. Significant effects were observed on the rate of broodiness by the photoperiod and stage, but the interaction of photoperiod and stage was not significant. The rate of broodiness for group 3 (5.9%) was significantly higher than other groups, with group 2 being the lowest (2.8%). Broodiness rate was the highest for weeks 41–47 (9.9%). Significant effects were observed on average egg-laying rate by photoperiod and stage: the rate of egg-laying of groups 2 and 5 were significantly higher than groups 1, 4 and 6.

4. There were no significant effects of photoperiod on PRL, LH and Mel concentrations at 26, 33, 40 and 54 weeks of age (P > 0.05), but at 47 weeks of age, PRL and LH concentrations of group 1 were significantly lower than those in other groups.

5. The study suggests that the photoperiod of group 2 (12L:2D:4L:6D) is optimal for the birds’ performance to give the lowest broodiness rate and the highest egg-laying rate during the whole laying period, and 41–47 weeks may be a key stage for the photomodulation of broodiness.     

Effects of immunisation against leptin on feed intake, weight gain, fat deposition and laying performance in chickens

1. Three experiments were conducted to study the effects of leptin on weight gain and body composition in laying hens. 2. The effects of immunisation against chicken leptin on feed intake (FI), fat deposition and laying rate were observed in laying Guangdong yellow-feathered hens. Ten hens were inoculated with leptin immunogen on d 3, 31, 63 and 84, together with 10 control hens immunised with bovine serum albumin (BSA). In the 100-d experiment, immunisation against leptin increased blood anti-leptin antibody titres, slightly reduced plasma T3 concentrations, slightly decreased FI and increased live weight; however, laying rate was significantly depressed and abdominal fat mass was increased by the end of the 100-d experiment. 3. Passive immunisation of 50-d-old pullets with yolk extract containing anti-leptin antibody IgY significantly increased FI within 6 h of treatment compared with physiological saline treated controls. 4. In growing 70-d-old pullets, inoculation with 0.5 (group 1) or 1 (group 2) ml leptin immunogen on d 1 and 28 of the experiment slightly increased FI and significantly increased daily gain compared with BSA-immunised control pullets. Abdominal fat mass on d 49 increased from 48+/-4.5 g in controls to 66+/-3.5 and 80+/-3.1 g in groups 1 and 2, respectively. 5. It was suggested that immunisation against leptin mimicked loss of leptin bioactivity and might become a novel technique to stimulate fat growth in certain types of animal production.     

Changes in plasma luteinizing hormone concentration in Turkey hens after switching from short-day to long-day photoperiods

Luteinizing hormone (LH) has been reported to increase in plasma shortly after switching photosensitive turkey hens from short-day (SD) photoperiods (6 hr light: 18 hr dark) to long-day (LD) photoperiods (14 hr light: 10 hr dark). An experiment was conducted to determine the timing and nature of these changes in plasma LH concentrations after the photostimulation of photosensitive turkey hens. The turkey hens were cannulated (jugular vein) to allow serial bleeding every 15 min for 48 hr. One group (controls) was continued under the SD photoperiod, and one group (treated) was switched to the LD photoperiod by the addition of 8 hr of light to the end of the photoperiod. In the control hens, no changes were seen in the observed or calculated baseline concentrations of LH or in the frequency and amplitude of LH peaks during the 48 hr of serial bleeding. In the treated hens, the observed and baseline concentrations of LH increased during the first LD scotoperiod, with a further increase during the second LD scotoperiod. This rapid increase was due to an increase in the baseline LH concentration, whereas no consistent changes were detected in the frequency and amplitude of LH peaks.     

Effect of active immunization against estrogen on gonadotropin response to testosterone propionate treatment in ovariectomized pony mares

An experiment was conducted to determine whether partial neutralization of estrogens via active immunization alters testosterone propionate (TP)-induced increases in FSH secretion after GnRH administration in ovariectomized pony mares. Twenty mares were used in a 2 X 2 factorial arrangement of treatments (n = 5/group). Factor 1 was long-term active immunization against either bovine serum albumin (BSA) or estrone-17-oxime-BSA. Factor 2 was 11-d administration of either vehicle (vegetable oil) or TP (175 micrograms/kg BW). Plasma concentrations of FSH were not affected (P greater than .1) by either factor. As expected, the FSH response to exogenous GnRH was threefold greater (P less than .05) in BSA-immunized mares treated with TP than in BSA-immunized mares receiving oil. However, immunization against estrogens reduced (P less than .05) this TP-induced increase in FSH response by 52%. Plasma concentrations of LH were decreased (P less than .08) by TP; this effect was not altered (P greater than .1) by immunization against estrogen. The LH response to exogenous GnRH was not affected (P greater than .1) by either factor. We conclude that aromatization of testosterone to estrogen is partially responsible for the increased FSH response to exogenous GnRH in TP-treated mares. In contrast, suppression of LH concentrations by TP appears to involve only the androgenic effect of TP.     

海兰褐蛋鸡和京粉2号蛋鸡的生长发育规律及初产蛋品质比较研究

[目的]研究相同饲养条件下海兰褐蛋鸡苗和京粉2号蛋鸡苗的生长发育规律,评价其初产蛋品质.[方法]选取1日龄海兰褐蛋鸡苗和京粉2号蛋鸡苗各500只,在相同条件下饲养,每周随机挑选60只个体测量体重,直到13周龄试验结束.采用Logistic、Gompertz和Von Bertalanffy 3种曲线模型对2种鸡苗的生长发...     

Ovarian follicular growth and maturity and follicular production of progesterone and oestradiol in response to porcine luteinising hormone and porcine follicle stimulating hormone in albino (S*AS) hens in vivo and in vitro

The effects of the SAS gene on follicular growth were studied by feeding Sudan IV and Sudan Black B, on follicular maturity by measuring P4 and E2 output of the 5 largest follicles (F1 to F5) in vitro, and on ovarian response (plasma progesterone, P4, and oestradiol, E2) to administration of porcine follicle-stimulating hormone (pFSH) and porcine luteinising hormone (pLH) in old laying hens. Albino hens had fewer dye rings in the yolks of their eggs than non-albinos (8.32 compared to 8.59) and the yolks from albinos weighed less. The numbers of normal and atretic follicles larger than 3 mm in diameter did not differ between the two genotypes. The P4 outputs from the F1 and F2 follicles were significantly greater for albino hens, but P4 production of other follicles was not different for the two genotypes. The P4 output of the F1 follicle in response to pLH was dose-dependent and greater for albino hens than for non-albinos. Porcine LH did not increase the follicular E2 output in either genotype. Administration of pLH, but not pFSH, increased plasma P4 and E2 concentrations, with no difference between genotypes. These data suggest that the F1 follicles for albino hens are precocious, resulting in a reduced growth period and a smaller weight at ovulation.     

Changes in luteinizing hormone-containing gonadotrophs after moulting induced by fasting and zinc in laying hens (Gallus domesticus)

The purpose of the present study was to investigate egg production performance, immunohistochemical (IHC) identification, localization and morphological characterization of moulted hen’s pars distalis luteinizing hormone (LH) gonadotrophs. This system has been validated for chicken LH by immunodetection of purified hormones on dot blots, western blotting and by specific labelling of cells on sagittal sections of chicken pituitaries. This study showed that egg production and egg weight increased significantly after zinc-induced moult when compared with fasting-induced moult. Luteinizing hormone-gonadotrophs are of numerous shapes and distributed throughout the adenohypophysis, with densely populated regions on the margins of pars distalis. Moulting of laying hens was associated with a significant increase in immunoreactive LH gonadotroph cell count and cell size, which peaked at the subsequent production stages. Zinc-induced moulting also caused a significant increase in LH gonadotroph cell size as compared with fasting-induced moulting. The nuclear size of LH-positive cells was distinct during decreased egg production. Our results validate the use of ovine LHβ antibodies for the IHC localization of chicken LH gonadotrophs. This technology was further applied to the characterization of the shape and morphological changes of gonadotrophs as a function of the egg production status of the birds.     

Tamoxifen advances puberty in the White Leghorn hen.

1. Tamoxifen (TAM) administration advances puberty in cockerels. In the present study the effect of TAM administration on the sexual development of White Leghorn hens was studied. 2. Two-week-old White Leghorn females were injected intramuscularly with TAM on alternate days at doses of 0.1 mg (0.1 TM), 1 mg (1TM), 5 mg (5TM) and 10 mg/kg body weight (10TM) respectively, while the controls were injected with maize oil (vehicle). The experiment was terminated at 23 weeks of age, when all the control hens laid eggs. Sample autopsies were made on chicks of 6, 14 and 23 weeks of age. 3. Body growth was not affected by any of the treatments. 4. Comb growth was accelerated by all doses of TAM, while hematocrit increased in the 1TM, 5TM and 10TM hens. 5. Egg laying advanced in the 0.1TM and 1TM birds, was delayed in 5TM hens and did not occur at all in the 10TM females. 6. TAM caused a precocious increase in plasma oestrogen and androgen, suppressed adiposity in a dose-related manner and, at low doses, advanced the development of the gonadal system. 7. At 23 weeks of age, when the gonadal system of the controls was fully active, TAM caused a dose-related depression in abdominal fat, liver, ovary, and oviduct weights, plasma total lipids and calcium concentrations and a dose-related increase in plasma oestrogen and androgen titres, and comb weight. 8. It seems that TAM increased gonadotropic activity and its androgen stimulating action, but suppressed peripheral signs of the elevated plasma oestrogen titres. Low doses of TAM enhanced gonadotropic activity and egg laying but the antioestrogenic effect depressed development of the gonadal system, suppressing egg production when high doses were administered. It therefore seems that oestrogens are necessary for normal ovarian development in hens.     

免疫血管活性肠肽调节鸡产蛋和就巢的机理研究

旨在研究免疫血管活性肠肽(Vasoactive intestinal peptide,VIP)和抑制催乳索(Prolactin,PRL)分泌对鸡产蛋和就巢的影响机制.试验1:对18周龄未开产的泰和鸡,分别在试验d1、d28、d56和d84免疫含VIP羧基端15肽片段的VIP-BSA偶联蛋白,观察对产蛋和就巢的影响.试验2:利用刚开产的23周龄粤黄鸡,在试验d1、d23、d48、d73、d98免疫VIP串联四聚体重组蛋白,观察对产蛋和就巢的影响,并在第98天检测卵泡发育和下丘脑、垂体、F1～F3级LYF颗粒层和膜层相关基因的表达.试验1中免疫VIP组在开产后高峰期(d55～d61)的产蛋率显著低于对照组,但高峰后的(d89～d103)产蛋率显著高于对照组,同时免疫VIP组的就巢发生也要迟于对照组.试验2中,VIP免疫组的产蛋率在试验初高于对照组;在d33将光照从12 h延长至16 h后,2组的产蛋率均快速上升;产蛋高峰后,免疫组产蛋率快速下降并在dS0～d105显著低于对照组.免疫VIP重组蛋白也降低了就巢的发生.2组鸡在d98的大黄卵泡、小黄卵泡和大白卵泡的数量无显著差异.免疫VIP重组蛋白并不影响下丘脑Gn-RH-Ⅰ和VIP、垂体LHβ和FSHβ的mRNA水平,但显著降低了垂体PRL的表达,也显著降低了垂体和下丘脑PRLR的表达.在检测的F1～F3卵泡组织中,免疫VIP重组蛋白也显著降低了F1和F3颗粒层的PRLR mRNA水平,降低了F1～F3颗粒层和膜层的LHR表达量,但对P450scc和StAR的表达量没有影响.两试验结果表明,免疫VIP能够降低PRL的表达和分泌,从而抑制产蛋引发的就巢发生,但是免疫VIP在抑制PRL表达分泌后也会抑制卵泡发育和产蛋,这一机制可能是通过影响卵泡组织LHR的表达而实现的.     

不同硒源及硒水平对产蛋鸡生产性能和蛋品质的影响

试验旨在研究添加不同水平的亚硒酸钠和酵母硒对产蛋鸡生产性能和蛋品质的影响。试验选用23周龄北京油鸡和罗曼粉杂交一代产蛋母鸡648只,随机分为12组,每组6个重复,每个重复9只鸡,进行为期8周的饲养试验。试验1~6组在基础日粮中分别添加含硒0.3、1.0、2.0、3.0、4.0、5.0 mg/kg的亚硒酸钠,试验7~12组在基础日粮中分别添加含硒0.3、1.0、2.0、3.0、4.0、5.0 mg/kg的酵母硒。结果表明,在产蛋鸡的饲料中添加5.0 mg/kg以内的亚硒酸钠或酵母硒都有提高产蛋率的趋势(P＞0.05),且对蛋品质无明显不良影响。若以提高产蛋率为目的,亚硒酸钠的添加水平以2.0 mg/kg为宜,酵母硒的添加水平以3.0 mg/kg为宜。酵母硒的使用效果优于亚硒酸钠。酵母硒组采食量和蛋壳强度显著高于亚硒酸钠组(P＜0.05),亚硒酸钠组蛋白高度和哈氏单位显著高于酵母硒组(P＜0.05)。     

Seasonal and photoperiodic regulation of secretion of hormones associated with reproduction in Magang goose ganders

This study examined the reproductive endocrine profile under natural and artificial photoperiods in Magang goose ganders. Group 1 ganders (n=8) served as non-treated controls and were exposed to natural photoperiod throughout the experiment from 13th January to 17th December 2004. Group 2 ganders (n=8) were exposed to 18 h long daily photoperiod for 60 days from 13 January till 15 March 2004 and again to 16 h photoperiod for 75 days till 10th October 2004, and the 11h short photoperiod in the remainder periods of the experiment. In control ganders, plasma LH concentrations were high in normal breeding seasons (August-March) and decreased to low levels in non-breeding season from April to July. Testosterone concentrations changed similarly to that of LH throughout the seasons. Seasonal pattern of PRL concentrations was opposite to those of LH and testosterone, with low values in breeding season and high values in non-breeding season. In artificial photoperiod treated ganders, increasing photoperiod increased PRL and decreased LH and testosterone concentrations, while decreasing photoperiod reversed these changes. There were no seasonal or photoperiod caused changes in plasma T3 concentrations in both control ganders and artificial photoperiod treated ganders. These results demonstrated that in Magang goose ganders that long photoperiod stimulates PRL secretion and decreases LH secretion, which terminates reproductive season in spring and early summer, and short photoperiod stimulates LH secretion and inhibits PRL secretion rendering ganders enter into reproductive season.     

Plasma prolactin responses to serial bleeding in turkeys

Changes in plasma prolactin (PRL) in response to serial bleeding by venipuncture were measured in turkeys of varying age, sex and reproductive condition. Serial bleeding increased plasma PRL levels in immature, ovariectomized (OVX), laying and non-laying females, but depressed PRL levels in broody (incubating) females. Immature males showed a positive PRL response, while mature males showed no significant response to serial bleeding. The effective stressor was shown to be repeated capture and restraint for serial bleeding and not blood loss. The pattern of the PRL response in OVX hens was not significantly influenced by variations in time required for capture and restraint or by variation in the fear reaction to capture. Habituation of OVX hens to serial capture and handling on 14 consecutive days did not significantly blunt the PRL response to serial bleeding. These results reaffirm the importance of understanding the role of physiological and psychological factors influencing PRL secretion in birds as well as the need to avoid undue stress in birds used for studies of PRL secretion.