Effects of livestock breed and rearing experience on foraging behaviour of yearling beef cattle grazing unimproved grasslands

The relative importance of breed versus rearing experience on the grazing behaviour and diet selection of beef cattle when grazing unimproved grassland was examined over 4 years. Suckler‐reared calves of a traditional (T) breed (North Devon) or a commercial (C) breed (Simmental × Hereford Friesian) were cross‐fostered and then reared either extensively (E) on unimproved grassland or intensively (I) on agriculturally improved fertilized grassland. As yearlings, the four groups of calves (Traditional breed + Extensive rearing (TE); Traditional breed + Intensive rearing (TI); Commercial breed + Extensive rearing (CE) and Commercial breed + Intensive rearing (CI)) grazed unimproved grassland dominated by Molinia caerulea, for 2 months, and foraging behaviour was studied in a test phase. There was a breed effect on total (bites + chews; TJM) jaw movement rate (T, 78·2 vs. C, 76·5 min^?1; F prob. = 0·041) during grazing and on the proportion of bites taken from plant communities with sward height ≥6 cm (T, 0·83 vs. C, 0·76; F prob. = 0·018). Rearing experience affected TJM rate in the first year in July (E, 80·0 vs. I, 76·8 min^?1; F prob. = 0·015) and August (E, 78·5 vs. I, 75·5 min^?1; F prob. = 0·046). The intensively reared animals grew less well on average during the test phase than those that had previous experience of the unimproved grassland as calves with their mothers (E, 0·16 vs. I, 0·09 kg day^?1; F prob. = 0·033). Our findings indicate that the rearing experience of livestock appears to be as important as the breed when designing grazing managements for nature conservation areas.     

A Method for Mass-rearing Aphidius gifuensis(Hymenoptera: Aphidiidae)

[Objective] This study presents a method for mass rearing of Aphidius gifuensis, a dominant endoparasitoid of Myzus persicae on tobacco in Southwest China. [Method] The tobacco cultivar Honghuadajinyuan(Nicotiana tabacum) was used as the host plant and M. persicae was the host insect. In a greenhouse, tobacco seedlings were reared in plastic trays. The seedlings at three-true-leaf stage were inoculated with two to three aphids per plant using aphid source with a parasitism rate of 47% ±3.9%. [Result] By this inoculation method, the aphids and parasites were simultaneously inoculated on host plants. After approximately 25 d of rearing, we were able to produce 82.5±5.17 aphid mummies per tobacco seedling. A total of 445 500 aphid mummies were produced in one greenhouse(36 rearing trays per greenhouse) during an approximately 50-day rearing period. The emergence rate was 93.4% ±2.76%, and 54% of the mummies were females. [Conclusion] The demonstrated technological feasibility of using tobacco seedlings for the mass rearing of A. gifuensis increases the potential for the biological control of M. persicae.     

短须裂腹鱼规模化人工繁育技术研究

2012—2013年,为提高短须裂腹鱼人工繁育能力,以刚涌出的清澈无致病菌和虫的地下泉水为水源,采用水流培育亲鱼、流水孵化受精卵、活体饵料培育鱼苗等关键技术,进行短须裂腹鱼规模化人工繁育技术研究。结果表明:2年共采捕野生短须裂腹鱼亲鱼403尾,在水流速度0.1~0.3 m/s、水温12~16℃、pH值6.5~7.0、溶氧6 mg/L以上的流水池中培育,平均驯养成活率49.4%,获成熟亲鱼234尾次;共催产亲鱼224尾次,产卵雌鱼133尾次,总产卵量127.3万粒,平均每尾雌鱼产卵0.957万粒;获受精卵93.8万粒,平均受精率为73.7%;受精卵在水温12.5~14.0℃的流水孵化槽中孵化199 h开始出膜,共孵出幼体85.5万粒,平均孵化率91.2%;共获2 cm仔鱼55.1万尾,平均出苗率58.7%;共获3.5 cm鱼苗45.2万尾,鱼苗培育成活率为82.0%。     

白沙参苗种中间培育关键参数研究

为了解决白沙参参苗个体小、抗逆性及抵御敌害生物的能力弱、成活率低、不利于增养殖的缺陷,研究了白沙参室内水泥池中间培育过程中的关键参数,并在最优条件下进行室内水泥池和室外池塘网箱的培苗,试验结束时测量参苗的体长和体重,计算成活率.结果表明,室内水泥池培育的关键技术参数如下:水温25～30℃,盐度25‰～35‰,培育密度2000～3000头/m2,光照强度2 000 lx.在上述最佳条件下,将体长0.3～0.5 cm、体重0.004 g的参苗16万尾,置于室内水泥池培育1个月后,参苗规格平均达到0.8～1 cm,存活率达到50％以上.然后将其转到室外网箱培养,更换网箱规格并及时疏苗,培育40 d时,参苗规格平均达到3 cm左右,存活率达到60％.     

平行串叶法小蚕片叶立体一日一回育技术的研究

在小蚕片叶立体一日一回育的基础上，试验了平行串法小蚕片叶立体一日一回育，与立体一日二回育比，节约用桑３％，节约劳力３６％，张种产量提高８．５％，还阐明了该法的技术要点。     

Tolerance response to water pH in larvae of two marine fish species, gilthead seabream, Sparus aurata (L.) and Senegal sole, Solea senegalensis (Kaup), during development

Gilthead seabream, Sparus aurata (L.) and Senegal sole, Solea senegalensis (Kaup) are two fish of primary importance in Mediterranean aquaculture. In the present study, the larvae of these species were exposed to different rearing‐water pH during 24 h to examine their tolerance. The 24‐h pHL50 values were calculated with low and high pH values at 7, 20 and 32 days after hatching (DAH) in S. senegalensis larvae, and 12, 20 and 52 DAH in S. aurata larvae. Low 24‐h pHL50 values ranged between 4.88 and 5.76, whereas high 24‐h pHL50 values ranged between 8.94 and 9.57 in S. senegalensis larvae. S. aurata larvae showed values of low 24‐h pHL50 that ranged between 4.82 and 5.55, whereas values of high 24‐h pHL50 ranged between 8.66 and 9.26. Both species showed similar tolerance response at all the tested ages. The high 24‐h pHL50 values found were close to pH values that eventually can be reached in the rearing tanks. The pH should be carefully controlled in rearing water during the first development stages of both species.     

省力化养蚕技术及其应用

降低生产成本，降低劳动强度，提高蚕桑生产比较效益，是当前和今后蚕桑生产稳定发展的重要问题，本文概要介绍我省省力养蚕技术的发展过程，提出了省力化养蚕技术规范，应用省力化养蚕技术的五条技术关键和推广措施以及应用效益。     

不同食料条件下密度因子对黄粉虫高龄幼虫生长发育的影响

分别以实用饲料和复合饲料在0.6、1.2、1.8、2.4和3.0头/cm3等5种饲养密度下饲养黄粉虫(Tenebrio molitor L.)高龄幼虫,观察了在不同饲料条件下不同密度对黄粉虫幼虫死亡率、幼虫增重、蛹重等指标的影响.结果表明,密度因子对黄粉虫高龄幼虫有显著影响,在两种不同饲料条件下饲养黄粉虫,低密度饲养时幼虫存活率、幼虫增重、蛹重及羽化率明显高于高密度饲养,但各指标间存在差异.     

酪蝇室内饲养技术研究*

 报道了酪蝇的饲养方法，并在室内27 ℃恒温条件下对比研究了火腿、人工饲料和奶酪3种食料对酪蝇幼虫和蛹的存活率、发育历期及蛹重的影响。结果表明，火腿是最适食料，人工饲料次之，奶酪最不适宜。饲养酪蝇时，使其老熟幼虫在软棉布中化蛹，便于蛹的收集。     

不同饲料不同龄期小蚕人工饲料育比较试验

用32个蚕品种杂交形式供试,比较了新老2种稚蚕人工饲料配方的疏毛率;结果表明新配方的24 h疏毛率普遍优于老配方,差异达到极显著水平;24 h疏毛率,老配方中只有6个蚕品种超过了98%,新配方中有21个蚕品种超过了98%,增加了15个蚕品种型式,新配方明显扩大了一代杂交种杂交率检验和小蚕共育的适用蚕品种范围.从不同龄期小蚕人工饲料育与全龄桑叶育的养蚕成绩和茧丝成绩看,用人工饲料进行小蚕共育基本可行,综合考虑各方面因素,共育到2龄后再改喂桑叶或分蚕出售给农民较好.