Growth, Survival, and Feed Conversion Rates of Hatchery-Reared Mutton Snapper Lutjanus analis Cultured in Floating Net Cages

Abstract.— The aquaculture performance of mutton snapper Lutjanus analis raised in floating net cages was assessed by measuring their growth, survival, and feed conversion rates during a growout trial conducted in a 3.2‐ha saltwater lake in the Florida Keys, Florida, USA. Approximately 10,500 hatchery‐reared finger‐lings were stocked in two circular, high‐density polyethylene (HDPE) net cages of 7‐m diameter × 7‐m deep (300 m²) and 10‐m diameter × 7‐m deep (600 m³) dimensions. Cages were stocked at 25 fish/m³ (3.2 kg/m³) and 5 fish/m³ (0.72 kg/m³), respectively. Fish grew from a mean of 16.5 g to 302.8 g (25.6 cm TL) in 246 days in the former cage and from a mean of 42.3 g to 245.6 g (23.8 cm TL) in 178 d in the latter cage. Growth rates in weight were best expressed by the following exponential equations: cage 1 (high stocking density): W = 20.716 e^0.0112x (r²= 0.83); cage 2 (low stocking density): W = 38.848 e^0.0118x (r²= 0.81). Length‐weight data indicate that hatcheryraised, cage‐cultured mutton snapper are heavier per unit length than their wild counterparts. There was no significant difference (P < 0.05) between the slopes of the two lines, indicating that fish in the two cages grew at the same rate. The length‐weight relationships for mutton snapper stocked in cages 1 and 2 are expressed, respectively, by the equations W = 0.000009 L ^3.11 (r²= 0.99) and W = 0.000005 L ^3.22 (r²= 0.97). Overall feed conversion rate for both cages combined was 1.4. Approximately 10% of the fish sampled exhibited some degree of deformity, particularly scoliosis. Overall survival rate was 70%. Results suggest that L. analis has potential for aquaculture development in net cage systems.     

我国玉米秸秆收运机械化发展现状分析

我国玉米秸秆资源丰富,综合利用发展潜力巨大。为此,详细归纳了目前我国玉米秸秆收运发展模式,分析了与玉米秸秆收运相关的主要机械类型、结构特点、工作流程、典型机型应用状况及机械化程度。从秸秆综合利用途径、经济效益、生产技术等方面分析了我国玉米秸秆收运机械化发展面临的困难,并针对我国玉米秸秆收运机械化程度较低、收运发展体系不完善等现状,从营造发展环境、拓展发展空间、构建供求新秩序、形成规模化经营与现代化管理模式、提供人才储备及创新产品技术等方面提出促进玉米秸秆资源综合高效利用和提高玉米秸秆收运机械化发展水平的建议,为玉米秸秆收运机械化快速、健康、稳定。     

家禽就巢性的影响因素及其内分泌调控机理研究进展

就巢性是家禽进行繁殖必不可少的行为，对家禽的繁殖能力有很大影响。家禽就巢性作为一个低遗传力性状，其受环境、内分泌及遗传3种因素调控。其中环境因素中光照、温度、饲养管理模式等都对家禽就巢性具有显著影响。与禽类就巢性密切相关的繁殖内分泌激素主要包括：促性腺激素释放激素（GnRH）、催乳素（PRL）、促卵泡激素（FSH）、促黄体素（LH）、孕酮（P₄）和雌二醇（E₂）。遗传是家禽就巢性的决定因素，就巢性候选基因研究主要基于内分泌研究中的相关繁殖激素。随着基因组测序技术发展，大量就巢性相关新基因被证实，为就巢性分子遗传机制的研究提供了新的思路。目前，家禽就巢性的遗传调控机制仍不清楚，开展就巢性的分子调控机制研究，将极大地提高家禽产蛋性能，促进优良地方禽类的保护、开发和利用。作者对环境、内分泌和遗传控制就巢行为的研究进行综述，并对禽类就巢行为的发生和调控机制进行探讨。     

我国主产区猕猴桃采后腐烂病病原多样性研究

猕猴桃采后腐烂在我国发生普遍.本试验对来自陕西、四川、湖北、山东和江西五省的773个猕猴桃病果进行组织分离,获得739个真菌分离株.经ITS序列比对及代表菌株的科赫式法则验证,确定其中722个菌株为猕猴桃采后腐烂病病原,属于以下11个属:Botryosphaeria、Diaporthe、Neofusicoccum、Al...