马岗鹅产蛋-就巢周期内卵泡发育的内分泌调控

旨在探讨马岗鹅产蛋-就巢周期内卵泡发育的内分泌调控机制。试验1：观察了马岗鹅产蛋-就巢周期内PRL、LH、P4和INB水平的变化和就巢期（第1天）、就巢终止期（第10天）、开产期（第25天）、产蛋高峰期（第40天）、停产期（第55天）和就巢期（第70天）卵泡的发育。试验2：在对马岗鹅终止就巢时（第1天）主动免疫重组鸡PRL蛋白（1 mg·只^-1）,并在开产前（第23天）和产蛋高峰期（第45天）加强免疫（0.8和0.5 mg·只^-1）,同时从第33天将每天光照由11 h增至16 h,观察对马岗鹅产蛋和就巢的影响。试验1结果表明,随着就巢的终止,PRL水平下降,LH、P4和INB水平上升。PRL在开产前降至最低,开产后又逐渐上升,就巢期达最高;LH则在开产前和产蛋期呈现两波分泌峰;P4和INB与PRL呈相反变化,在产蛋高峰期最高,就巢期最低。鹅群在第24天恢复产蛋,开产前有约10枚大白卵泡（LWF）发育为小黄卵泡（SYF）和大黄卵泡（LYF）;在约30 d的产蛋期内,平均每只产蛋约8枚,产蛋结束后90%的鹅发生就巢。试验2结果表明,对马岗鹅主动免疫PRL蛋白一定程度推迟（P〈0.05）了开产后产蛋率的上升,并一定程度抑制就巢的发生;而在延长光照15 d后,免疫组的产蛋和就巢则快速升至与对照组相当水平。整个试验期,2组累计就巢均达到100%,但免疫组比对照组多产蛋1枚（8.0 vs 7.0）。结果提示,PRL和LH的交替分泌调控马岗鹅的产蛋就巢周期;卵泡发育时分泌的INB,以及由P4促进分泌的PRL,调节周期中卵泡发育和产蛋的数量。PRL不仅促进就巢发生并导致周期内较低等级卵泡的闭锁,可能还在开产前后具有促进卵泡发育和产蛋的作用。     

光照影响鹅繁殖性能和激素水平的研究进展

本文系统阐述了光照时鹅繁殖性能和激素水平的影响。光照时间的增长或缩短可以引起母鹅产蛋量、卵泡发育和公鹅繁殖性能的改变;光照变化可以引起鹅促性腺释放激素(GnRH)、催乳素(PRL)、卵泡刺激素(FSH)、促黄体生成素(LH)、甲状腺素(T_4)、睾酮(tT)等激素水平的变化,通过激素水平的变化引起鹅繁殖性能的改变。     

鹅繁殖就巢机理研究进展

鹅是季节性繁殖禽类且大多数品种具有较强的就巢性,其中光照是重要的控制因子.光照通过作用于下丘脑的光感受器将光电磁信号转换为激素信号,然后进行一系列信号传导,通过下丘脑-垂体-性腺轴调节鸟(禽)类的生殖活动.下丘脑在光照调控下释放GnRH和VIP,促进PRL的分泌,且使PRL分泌呈季节性变化.PRL表达量的上升与就巢行为的起始和维持具有密切的相关性,在生殖功能退化时达到峰值.目前从分子水平对PRL及相关功能基因进行了大量研究,通过主动或被动免疫PRL或VIP抗体,可以降低PRL的分泌,抑制就巢行为.     

鹅繁殖就巢机理研究进展

鹅是季节性繁殖禽类且大多数品种具有较强的就巢性,其中光照是重要的控制因子。光照通过作用于下丘脑的光感受器将光电磁信号转换为激素信号,然后进行一系列信号传导,通过下丘脑-垂体-性腺轴调节鸟（禽）类的生殖活动。下丘脑在光照调控下释放GnRH和VIP,促进PRL的分泌,且使PRL分泌呈季节性变化。PRL表达量的上升与就巢行为的起始和维持具有密切的相关性,在生殖功能退化时达到峰值。目前从分子水平对PRL及相关功能基因进行了大量研究,通过主动或被动免疫PRL或VIP抗体,可以降低PRL的分泌,抑制就巢行为。     

鹅繁殖季节的调控和配套技术

我国南北各鹅种的季节性繁殖现象可分为3种类型,即完全长日照繁殖型、部分长日期繁殖型和短日照繁殖期.鹅繁殖季节性的差异受外界光照周期变化的影响,光照影响垂体促性腺激素和催乳素的分泌水平从而调节年度繁殖产蛋季节.通过遗传选育和其他畜牧生产管理技术如雏鹅的留种季节和营养供应水平等,都能部分影响鹅的繁殖季节性.而通过人工控制程序,则可以完全克服鹅的繁殖季节性问题,并配之以环境控制和营养调控技术,以有效避免热应激和水体细菌和内毒素污染等问题.通过调控种鹅在春夏季的非繁殖季节正常产蛋繁殖,开展鹅的反季节生产,从而克服雏鹅生产的季节性进行肉鹅的全年均衡生产.     

保障种鹅高产的技术措施

(一)掌握鹅繁殖规律鹅繁殖有明显的季节性。一般是夏季炎热季节休产。据研究,这是由于长短光照周期的变换刺激引起的,因此,与鸡、鸭等家禽相比,鹅的产蛋周期很短。鹅的繁殖特性还表现在公母鹅有固定配偶的习性。据观察,有的鹅群中30%～40%的母鹅和20%的公鹅是单配偶。鹅产蛋具有一定的规律性,不同品种的产蛋规律差异往往很大,掌握鹅产蛋规律,对于科学饲养、节约饲料成本以及安排休产期的     

性活动期不同光照时数对广东鹅繁殖和生理的影响

前言据调查,广东鹅种每年都有严格的繁殖期和休产期,即每年6月下旬至次年4月上旬为繁殖期,随后是换羽休产期。为寻求广东种鹅繁殖季节性的原因,探讨广东鹅全年繁殖性能的规律,我们进行了这一项试验,初步证明用人工控制光照技术改变广东鹅繁殖性,提高其繁殖力是可行的。在此基础上,我们进一步于广东鹅性活动期进行了本项研究。     

公火鸡外周血浆促黄体激素、睾酮浓度的变化及其与精液品质相关性的研究

8只公火鸡自然光照下饲养,每隔10d收集一次血样和精样,连续5个月(6-10月份)。用放射免疫法测定外周血浆的促黄体激素及睾酮浓度,并用常规方法估测精液品质。结果表明,血浆LH浓度从6月上旬到10月下旬逐步降低,其与白昼长度及湿度呈显著的相关性(r分别为0.553和-0.586)。血浆睾酮浓度的变化趋势与LH相似,血浆睾酮浓度与LH浓度、白昼长度呈显著的相关性(r分别为0.747和0.953)。射精量的变化与白昼长度的变化一致,相关系数为0.655。本实验还表明,LH与射精量呈弱正相关,而与精子密度和死亡精子百分数呈中等强度正相关(r分别为0.368、0.591和0.553)。睾酮浓度与精液品质指标皆呈弱正相关。公火鸡换羽时,血浆LH浓度、射精量,精子密度及死亡精子百分数显著低于非换羽期,睾酮浓度没有发生明显的变化。     

光照调节对狮头鹅反季节繁育性能的影响

本试验探讨了光照调节对狮头鹅反季节繁育性能的影响,结果表明:(1)春季缩短光照(11h)能使鹅提前进入下一轮繁殖期,而且每只鹅平均产蛋33.72枚,达到了自然繁殖的水平;长光照导致狮头鹅生产紊乱,繁殖性能差。(2)春季缩短日照时间可以使狮头鹅的开产期提前,而且光照越短,开产期越早,但鹅的产蛋性能会下降。(3)人工光照的效果与自然光相同,但大棚内的温度和封闭环境会大大降低种鹅的繁育性能。因此,在反季节繁育中,短光照促进而长光照抑制狮头鹅的繁殖活动,春季采用11h短日照是最佳选择。通过在冬季限制饲养和人工换羽,春季缩短光照,可以逆转狮头鹅的繁殖季节性,并且使种鹅表现出完全正常的产蛋性能,从而进行狮头鹅种鹅的反季节生产。     

环境条件和营养水平影响鹅繁殖性能及激素表达、分泌的研究进展

鹅是季节性繁殖动物,其繁殖活动受光照、温度、营养水平和养殖模式的调控。文章主要介绍环境条件和营养水平对鹅繁殖性能、激素水平和相关基因表达的影响,为种鹅的繁殖调控和生产提供理论参考。     

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.     

Effects of artificial supplemental light on the reproductive season of geese kept in open houses

1. New lighting programmes were designed to change the pattern of goose reproduction, based on the response of predictable avian photoperiodic stimulation. The objective of this study was to evaluate the efficiency of a long photoperiod of 20L on shifting goose reproduction to the non-breeding season in an open housing system. 2. Eighty mature White Roman geese were randomly allocated into 4 groups (male:female = 1:4). The supplemental lighting programmes with a daily photoperiod of 20 h were initiated on 22 November and withdrawn when 90% of geese were moulting in the treatment groups. Artificial light intensities of 220, 120 and 20 lux were provided to experimental groups A, B and C, respectively. In contrast, the geese in control group D were kept under natural lighting conditions throughout this study. 3. The annual reproductive curves of all the experimental groups consisted of two separate laying periods. The first period was induced by the supplemental lighting programme while the second was induced by the naturally increasing photoperiod in this subtropical region. The first laying period of the experimental groups occurred in the breeding season, and the second was relocated to the non-breeding season. 4. The supplemental lighting could shift the laying periods of geese to the non-breeding season and had no significant effect on annual reproductive performance. The supplemental light programmes described here were able to manipulate the reproductive season of geese reared in open houses, which would be of practical value.     

Effects of dietary meals containing different levels of phytoestrogens on reproductive function in Bilgoraj ganders

The aim of this study was to investigate how long-term feeding of ganders with diets containing different levels of phytoestrogens affects the morphometry of testes, plasma steroid levels, sperm parameters and reproductive performance. Male Bilgoraj geese were fed diets containing grass meal (with low phytoestrogen levels) and those containing alfalfa meal and soybean meal (with higher levels of phytoestrogens). Testes were obtained from ganders at the peak of mating and the ongoing laying period as well as at the beginning of photorefractoriness. The morphometric parameters were measured in frozen testicular sections. Blood was collected monthly from December to June, and plasma testosterone, androstenedione and corticosterone concentrations were determined. During the mating season, semen was collected and its quantity and quality were investigated. In the flocks (ganders with geese) reproductive output was noted. Seasonal changes were observed in the morphology of testes and in plasma testosterone, androstenedione and corticosterone concentrations in ganders. The feeding of ganders with dietary meals containing higher levels of phytoestrogens did not affect the plasma steroid contents or the majority of the morphometric parameters of testes, except for the height of the seminiferous epithelium, which was lowered. Moreover, diets with higher levels of phytoestrogens decreased the volume of ejaculates and the percentage of normal spermatozoa. However, these changes were not reflected in the fertilisation rates.     

Effects of season, age and increased photoperiod on reproductive hormone concentrations and testicular diameters in thoroughbred stallions

Testicular diameters and monthly blood samples were obtained from 83 stallions aged 4 to 22 years that were maintained on Central Kentucky Thoroughbred stud farms. The effects of age, season, and exposure to increased photoperiod (16 hours light/day, December 15 to April 1) on testicular diameters and plasma concentrations of FSH, LH and testosterone were studied.The results indicated that Thoroughbred stallions show distinct seasonal and age related changes in most of the reproductive parameters studied and that exposure of such stallions to increased photoperiod produced significant alterations in these changes. Although lighting stimulated testicular growth and testosterone secretion early in the breeding season such changes were short lived. Lighted stallions appeared to become refractory to the lighting program since both testicular size and plasma testosterone concentrations were significantly reduced by June.     

Prolactin plays a stimulatory role in ovarian follicular development and egg laying in chicken hens

The aim of this study was to show a stimulatory role in ovarian follicle development by prolactin (PRL) in chicken hens. In experiment 1, anti-PRL antibodies were generated in hen plasma by intramuscular administrations of recombinant PRL antigen. Egg laying remained at levels lower (P < 0.05) in the PRL-immunized group than in the BSA-immunized group of hens, whereas development of incubation was depressed in the former but not the latter group. Throughout the experiment, plasma PRL concentrations were lower in the PRL-immunized hens than in non-incubating control hens; LH concentrations were similar between the PRL- and BSA-immunized hens until the end of the experiment when LH was lower in the BSA-immunized hens (P < 0.05). In experiment 2, anti-PRL receptor (PRLR) antibodies were raised in hens with the use of immunizations against recombinant PRLR extracellular domain. Immunization against PRLR initially increased the egg-laying rate when measured under the short photoperiod (12 h) but blocked the laying rate increase that occurred in the BSA-immunized control hens when the photoperiod was extended from 12 to 16 h. The development of incubation behavior was not affected by immunization against PRLR nor was plasma PRL or LH concentration. In experiment 3, when the egg-laying rate was depressed in PRL immunization hens, developmental speed of large white follicles was found to be slower than in the BSA-immunized control hens (P < 0.05). These results indicate that immunization against PRL slows down ovarian follicular development and reduces hen egg-laying performance, suggesting that PRL plays a stimulatory role in ovarian follicular development in chicken hens.     

Effects of lighting intensity on growth and reproductive performance of breeder geese

This study investigated the effects of lighting intensity on egg production among white Roman geese kept in an environmentally controlled house. Two hundred and fifty-two White Roman geese aged 10 mo were randomly distributed among 12 pens, with each pen containing 5 ganders and 16 females on the floor, based on a completely random design (CRD). At the beginning of the study, each treatment group was comprised of 5 ganders and 16 geese in each pen; these groups included: control (40 lux group), geese under 170 lux (170 lux group), geese under 300 lux (300 lux group), and geese under 430 lux (430 lux group). The age of the geese at first lay was 10 mo, on average. The results showed that geese under 40 lux in egg number per goose or laying rate had lower than those of the 430 lux group. The reproductive characteristics were no different for the 170 lux, 300 lux, or 430 lux light groups. The hatchability in the 170 lux light group was significantly higher than in the 40 lux light group (P < 0.05). Moreover, the egg weight in the 170 lux and 430 lux groups was significantly heavier than the 40 lux light group (P < 0.05). Therefore, if lighting intensity supplementation of lux is defined as X (lux/geese), and egg number production is defined as Y₄ (egg), then Y₄ = 35.7 + 0.46X-0.002X²+0.00000296X³ (R² = 0.868, P < 0.001) for the entire experimental period. In conclusion, geese raised under 170 lux lighting intensity in an environmentally controlled house achieved higher hatchability and egg weight during the laying season.     

Lactation Biology Symposium: effects of photoperiod on mammary gland development and lactation

Photoperiod, or the daily sequence of light and dark, has dramatic effects on many physiological systems across animal species. Light patterns alter melatonin secretion profiles and, subsequently, the release profiles and circulating concentrations of several hormones that influence a variety of physiological responses. Although the impact of photoperiod on reproductive processes is perhaps the most common example, it is often the seasonal aspects of ovulation and anestrus that are considered. However, in cattle, the final phase of reproduction, that is, lactation, is significantly influenced by photoperiod. In contrast to short days (SDPP; 8 h light:16 h dark), exposure to long days (LDPP) of 16 to 18 h of light and 6 to 8 h of darkness increases milk yield 2 to 3 kg/d, regardless of the stage of lactation. There is evidence that this LDPP effect is due to increased circulating IGF-I, independent of any effect on GH concentrations. Cows that are housed under SDPP during the dry period have increased mammary growth and produce 3 to 4 kg/d more milk in the subsequent lactation compared with cows on LDPP when dry. While cows are on SDPP, circulating prolactin (PRL) diminishes but expression of PRL receptor increases in mammary, liver, and immune cells. Moreover, PRL signaling pathways within those tissues are affected by photoperiod. Further, replacement of PRL to cows on SDPP partially reverses the effects of SDPP on production in the next lactation. Thus, effects on dry cows are mediated through a PRL-dependent pathway. Before maturity, LDPP improve mammary parenchymal accumulation and lean body growth, which lead to greater yields in the first lactation. The accumulated evidence supports the concept that photoperiod manipulation can be harnessed to improve the efficiency of production across the life cycle of the dairy cow.     

维生素、矿物质与能量蛋白质水平对浙东白鹅母鹅繁殖性能、血液生殖激素浓度及生殖轴相关基因mRNA相对表达量的影响

本试验通过在饲粮中添加维生素与矿物质、调整饲粮能量蛋白质水平,旨在研究其对浙东白鹅母鹅繁殖性能、血液生殖激素浓度和生殖轴相关基因mRNA相对表达量的影响.选择138只月龄相近的浙东白鹅种母鹅,按体重相近原则分为3组,分别饲喂不同的饲粮,试验期150 d,测定繁殖性能(平均产蛋数、平均蛋重、受精率和孵化率)、血液生殖激素[卵泡刺激素(FSH)、促黄体生成素(LH)、孕酮(P4)、雌二醇(E2)、催乳素(PRL)]浓度和生殖轴相关基因[促性腺激素释放激素(GnRH)、卵泡刺激素-β(FSHβ)、雌激素受体1(ESR1)、雌激素受体2(ESR2)、卵泡刺激素受体(FSHR)、催乳素(PRL)、催乳素受体(PRLR)] mRNA相对表达量的变化.结果表明:1)添加维生素与矿物质可显著提高浙东白鹅母鹅第1产蛋周期平均蛋重和受精率(P＜0.05);提高第2产蛋周期内血液FSH和P4的浓度,降低LH浓度,改变E2、P4和PRL浓度波动(P＜0.05);下调下丘脑PRLR、垂体PRL和卵巢PRLR基因的mRNA相对表达量(P＜0.05),上调卵巢ESR2基因的mRNA相对表达量(P＜0.05).2)调整饲粮能量蛋白质水平可显著提高浙东白鹅母鹅第2产蛋周期平均蛋重(P＜0.05);提高浙东白鹅第2产蛋周期内血液LH浓度,降低FSH浓度,改变E2和P4浓度波动(P＜0.05);上调下丘脑GnRH、垂体PRL和PRLR基因的mRNA相对表达量(P＜0.05),下调卵巢FSHR基因的mRNA相对表达量(P＜0.05).由此得出,添加维生素与矿物质、调整饲粮能量蛋白质水平可通过影响产蛋周期内部分血液生殖激素浓度和波动,局部调节生殖轴相关基因的mRNA相对表达量,改善浙东白鹅母鹅的繁殖性能.     

鹅对11种非常规饲料代谢能和纤维利用率的研究

本研究旨在探索鹅对不同非常规饲料的利用率。试验以30只成年太湖鹅公鹅为研究对象,随机分为5组,每组6个重复,每个重复1只鹅,其中1组为内源排泄物对照组。空腹24h后,每组强饲1种饲料,各组内每只鹅强饲量相同,内源排泄物对照组不强饲。采用平板收粪法收集24h排泄物。2次试验间恢复期12d。测定生产中常见的11种非常规饲料代谢能(ME)和中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、半纤维素(HC)利用率。结果表明:鹅对啤酒糟、白酒糟、瘪稻、黑麦草粉、稻壳、玉米秸、稻草、麦秸、麦糠、平菇菌糠、花生藤的真代谢能(TME)分别为9.29、8.67、8.97、5.89、3.85、3.10、3.32、3.02、5.29、2.48、3.15M J/kg。用TME法测得的11种非常规饲料的NDF利用率为6.14%~45.01%,ADF利用率为4.52%~32.57%,HC利用率为18.45%~61.59%。TME最佳一元预测方程为TM E=12.205-0.232CF(R2=0.817)。研究结果显示鹅对非常规饲料有较高的利用率,能量利用率和粗纤维(CF)的含量呈极显著的负相关。试验所测ME值可为非常规饲料合理利用,准确计算与调整鹅饲料配方提供参考依据。     

肉鹅H5亚型禽流感疫苗免疫效果的研究

选用H 5亚型禽流感油乳剂灭活疫苗(H 5N 1,R e1株)对马岗鹅作首免日龄、免疫次数与免疫剂量的免疫试验。结果表明,雏鹅在7、14或21日龄作1次免疫均产生免疫应答,其中14与21日龄免疫组免疫后第5周抗体水平均达4 log2以上,抗体动态变化均值与峰值均高于7日龄免疫组2~3个滴度。用0.5、1和2 m l/只3个剂量对14日龄雏鹅的免疫试验中,0.5m l组抗体水平上升过程缓慢,免疫后4周抗体水平才达4 log2以上,1与2 m l组在免疫1周后上升速度较快,免疫后2周即达4 log2以上,抗体水平相近,但2 m l免疫组免疫后5~7周抗体水平均低于1 m l免疫组。说明接种剂量为1或2 m lH 5N 1油苗比接种0.5 m l的免疫效果好,尤以1 m l免疫剂量效果最好。雏鹅在7、14日龄或14、21日龄作2次免疫和7、14、21日龄作3次免疫,首免后抗体上升速度快,各检测点抗体水平均值相近,均在首免后3周达到4 log2以上,4~5周达6 log2以上,4~7周的抗体水平均高于14日龄1次免疫组,且提前2周达到4 log2以上,说明2次、3次免疫组的抗体水平高于1次免疫组,而2次与3次免疫组的抗体水平无明显差异。以上结果说明,在肉鹅生产的禽流感免疫中,选择以14日龄首免0.5 m l/只,21日龄2免接种1 m l/只可取得较为理想的免疫效果。