Reproductive seasonality in a swamp-locked African cichlid

Abstract –  This study quantified the seasonal pattern of reproduction in a swamp-dwelling population of the African cichlid Pseudocrenilabrus multicolor victoriae. In the hypoxic waters of the Lwamunda Swamp, Uganda, P. multicolor was reproductively active throughout the year, even during the peak of the dry seasons. However, the degree of activity was seasonal, with rainfall providing a predictor of the percentage of ripe, mature females. There was no correlation between aquatic oxygen availability dissolved oxygen (DO) and either adjusted mean gonad mass or percentage of mature females, suggesting that DO is not limiting reproductive activity in this system. Reproductively mature females were larger during drier periods and may maximise their lifetime reproductive success by producing young throughout the year; but with a lower brooding efficiency. A comparison with Welcomme's (1969) study of a river-swamp system feeding Lake Victoria suggests that reproductive patterning is variable among populations of P. multicolor and may reflect adaptive response to chronically hypoxic conditions in the Lwamunda Swamp.     

立体育雏笼不同层面温度变化规律及其对固始鸡生长发育的影响

逐日测定了4层立体育雏笼不同层面温度及位于育雏笼不同层面的四组固始鸡0-4周龄生长发育情况。结果表明:4层立体育雏笼的二层温度与四层、三层及一层温度之间有极显著相关关系,其相关系数分别为0.9351、0.8895和0.7667,并建立了二层与各层温度间的回归方程。0-4周龄固始鸡在不同层面温度下体重、料重比、成活率均无显著差异,胫长在1-3周龄差异显著或极显著,第四周差异不显著,说明对固始鸡在28.5℃的低温下开始育雏是可行的。     

光照强度对育雏期蛋鸡啄羽和其他行为的影响

从第4周到第6周,将320只海兰白羽蛋鸡雏,按照试验设计采用4个水平随机分组,每组16个重复,每个重复5只鸡,并将其饲养在5、10、15、20lx4个不同的光照强度条件下。观察鸡只的啄羽行为、采食行为、趴卧行为、修饰行为、寻食行为、饮水行为、站立行为和走动行为。试验发现,光照强度对育雏期蛋鸡啄羽的影响很大;随着光照强度的增加,育雏期蛋鸡的啄羽、修饰、寻食、饮水、站立和走动行为呈增加趋势;采食和趴卧行为呈下降趋势。     

笼养与平养育雏对雏鸡生长性能影响的比较研究

选择用笼养和平养两种育雏方式对不同品种1日龄雏鸡进行饲养,试验设计分处理组与对照组,试验组为笼养育雏,对照组为平面育雏,都以煤炉作为育雏保温源.每处理10个重复,每重复120只鸡,试验全期记录鸡的采食量、疾病发生率,并分别在第10、20、30日龄时,称取每重复体重,计算处理组保温成本(煤耗费用)、日增重、料肉比、生长均匀度、疾病发生率等指标.结果显示,与平养育雏相比,30日龄时笼养育雏4个品种(青脚麻E、广西花鸡、广西土2号、新矮脚黄A)的保温费用分别减少0.12、0.24、0.30、0.12元,累积增重分别提高170 g(P＜0.05)、102 g (P＜0.05)、35 g(P＞0.05)、60 g(P＜0.05);料肉比分别降低0.23 (P＜0.05)、0.12(P＞0.05)、0.23 (P＜0.05)和0.21(P＜0.05);30日龄鸡群均匀度分别提高11％ (P＜0.05)、7％(P＞0.05)、9％(P＞0.05)、15％(P＜0.05);笼养育雏组未发生球虫病,呼吸道疾病发生率显著低于平养育雏.结果表明,笼养育雏显著降低成本,提高生产性能,是有效阻断疾病发生的科学育雏方式.     

鸡低温育雏研究进展

低温育雏技术的研究目的是减少能源消耗 ,降低生产成本。低温育雏对鸡生产性能的影响 ,不同学者所得结论不尽一致。考虑雏鸡生理特点 ,采用适宜的施温制度是保证低温育雏技术成功的关键。在北方寒冷地区生产实践中开发低温育雏新技术具有重要意义     

不同光色 LED 灯对育雏期文昌鸡生长性能的影响

【目的】基于鸡不同时期对光环境的不同需求,研究最佳的光照体系。采用定制的5 W LED灯作为人工光源,研究白、暖白、红、黄、蓝、绿、紫7种光色对育雏期文昌鸡生长性能的影响,确定育雏期适合文昌鸡养殖的最适光色。【方法】将630只体重相近的1日龄文昌鸡母鸡,随机分配到7个不同光色处理中,每个处理3个重复,每个重复30只鸡,笼养、自由采食和饮水。24 h光照,试验周期8周。【结果】8周龄时蓝光处理文昌鸡平均体重最高达793.16 g,比红光、白光和绿光处理文昌鸡分别重58.68、45.17、45.77 g,差异显著。蓝光处理文昌鸡平均体增重与红光、绿光和白光处理文昌鸡差异显著,蓝光处理文昌鸡体增重比白光对照处理增重45.12 g,红光处理文昌鸡体增重最少。试验全期,蓝光处理文昌鸡群体体重均匀度最好,在90%以上。蓝光处理与绿光处理文昌鸡体增重均匀度差异显著;蓝光处理文昌鸡体增重均匀度最好,其次是白光和暖白光处理。白光处理文昌鸡料肉比最低,且与黄光处理差异显著。各处理间鸡只死亡率差异不显著。【结论】综合生长体重、群体均匀度和料肉比各项指标,与白光对照处理对比,LED蓝光可显著促进育雏期文昌鸡的生长,且提高群体体重均匀度,其次是紫光和黄光,而红光抑制鸡只生长,绿光处理群体体重均匀度最差。     

微生态制剂对绿壳蛋鸡的育雏效果

为微生态制剂在绿壳蛋鸡育雏生产中的应用提供参考,选择1日龄健康长顺绿壳蛋雏鸡600只,随机分为5个组,即对照组饲喂基础日粮,试验Ⅰ～Ⅳ组分别在基础日粮中添加0．008％、0．01％、0．012％和0．02％的微生态制剂,进行为期21 d 的饲养试验。结果表明：试验Ⅰ～Ⅲ组的日增重比对照组分别提高9．13％、6．01％和1．20％,料重比分别比对照组低12．35％、7．82％和11．52％;试验Ⅰ组的法氏囊指数显著高于对照组（P ＜0．05）,脾脏指数显著低于对照组（P ＜0．05）,其余各组间法氏囊指数和脾脏指数差异均不显著（P ＞0．05）。添加适量的微生态制剂能明显改善雏鸡生长,促进营养物质的消化吸收,提高饲料转化率,增强免疫力,其中以添加0．008％效果最好。     

Success and failure: The role of relative humidity levels and environmental management in liveEimeria vaccination of cage-reared replacement layer pullets

Contrary to the traditional view that layer flocks housed in conventional cages are unlikely to suffer coccidiosis caused byEimeria species, this enteric disease has become an emergent issue. Coccidiosis outbreaks in layers are frequently associated with the failure to develop protective immunity at a young age. Layer hens housed in cages are usually sourced from replacement layer pullets housed in similar cages in the rearing barn. Live coccidiosis vaccines administered to young chicks provide a small dose of vaccine oocysts that infect and replicate within the vaccinated birds, resulting in the release of progeny oocysts into the rearing environment; these oocysts must become infective (i.e., sporulate) and then reinfect the partially immune birds in order for the vaccine to generate complete protective immunity. Three factors are needed for successful oocyst sporulation: temperature (4 to 37°C; optimal 29°C), oxygen access, and adequate RH. The purpose of this study was to assess the degree of protective immunity elicited by birds spray-vaccinated with a live coccidiosis vaccine at the hatchery. During the critical period for oocyst sporulation and cycling, RH levels decreased to 13 to 19%, resulting in inadequate oocyst cycling and minimal protection against homologous challenge at 6 and 12 wk of age. This vaccination failure highlights the need to monitor RH in the barn and modify the barn environment so that conditions promote, rather than impede, the success of live coccidiosis vaccines.     

溴隐停与克罗米芬对鸡抱窝行为及醒抱后生产性能的影响

将36只抱窝的丝羽乌骨鸡随机分为3组,Ⅰ组为对照组,Ⅱ组第1~2天每只鸡每天喂服溴隐停1.25 m g,第3~7天每只鸡每天喂服克罗米芬12.5 m g;Ⅲ组,第1~2天每只鸡每天喂服溴隐停0.625 m g,第3~4天每只鸡每天喂服溴隐停1.25 m g,第5~6天每只鸡每天喂服克罗米芬25 m g,第7天每只鸡每天喂服克罗米芬12.5 m g,研究溴隐亭和克罗米芬对抱窝鸡血液中生殖激素含量、抱窝持续时间和产蛋性能的影响。结果表明,Ⅱ组就巢持续期平均为6.67 d,Ⅲ组平均为6.83 d,对照组平均为8.58 d;对照组、Ⅱ组和Ⅲ组使用药物后开始产蛋的平均时间分别为17.42,15.92和14.58 d;处理后1个月内的平均产蛋率分别为37.72%,59.65%和53.51%;第7天血清中雌激素含量分别为146.6,170.9和210.45 pg/mL。     

豫麦16的选育特点及其产量潜力

豫麦１６的选育特点是：采用多抗源异地材料作亲本，扩大Ｆ２种植群体规模，Ｆ４选择特优系并配合抗条锈病、白粉病鉴定，Ｆ５进行多点产量试验。通过边试验，边繁殖、边提纯的方法。结合高产栽培试验和组织大面积高产示范，加快了育种进程与推广，初步明确了豫麦１６具有每公顷７５００－９０００ｋｇ的高产潜力，探讨了进一步选育高产品种的育种目标。