饲用耐高温酶的研究与应用

随着养殖业的迅速发展，酶制剂作为一种高效、安全、无污染、多功能的“绿色”饲料添加剂越来越受到人们的青睐。大量的试验证明，在饲料中添加一定比例的酶制剂可以补充动物体内消化酶的不足，明显提高动物饲料的利用率，促进动物生长，改善生态环境和防治动物疾病等等。目前，大多数饲用酶在饲料中的应用大多以干粉粒的形式在饲料加工调     

饲用酶制剂在水产动物营养中的研究应用

饲用酶制剂能够促进饲料中营养成分的分解和吸收,提高动物生产性能,提高饲料转化率,降低粪便污染和动物死亡率,已被公认为是一种无残留、无污染、无公害的绿色环保型添加剂,在畜禽上研究较深,应用很广,目前越来越多地应用于水产养殖中。本文主要阐述饲用酶制剂的种类、饲用酶制剂在水产动物中的研究应用以及饲用酶制剂存在的问题。     

酶制剂在水产养殖上的应用研究概况

饲用酶制剂越来越多地应用于水产养殖中。介绍了酶制剂对水产动物消化机能、生长和饲料转化率、饲料中适宜添加量、内源性酶和养殖环境影响等方面的研究情况。提出了存在的问题及发展方向。     

酶制剂在肉鸡安全生产中的应用

酶制剂是一种以酶为主要功能因子的饲料添加剂。饲料中添加酶制剂可补充动物机体内源酶的不足,消除抗营养因子,提高饲料利用率,促进畜禽生产,减少环境污染,具有一定的经济效益和生态效益。介绍了酶制剂的作用机理,分析了酶制剂在肉鸡安全生产中的应用,并对酶制剂在实际应用中应注意的问题作简要探讨。     

饲用酶制剂在规模养猪中的应用试验

添加饲用酶制剂不仅能有效地消除饲料抗营养因子和毒素的有害作用,而且能全面促进饲粮养分的分解消化和吸收利用,提高畜禽的生产性能和增进畜禽健康。应用饲用酶制剂有利于开发非常规饲料资源,提高常规饲料的利用率,减少畜禽排泄中有机物、氮和磷的排出量,保护和改善生态环境,提高饲料和规模养猪企业的经济效益。为验证酶制剂在规模养猪中的实际效果,选用120头45日龄的杜大长杂交断奶仔猪分为两组,试验组在对照组日粮的基础上添加华芬酶0.2%,以观察华芬酶在断乳仔猪玉米豆粕型日粮中的饲养效果。试验结果表明:试验组的日增重比对照组提高8.84%;饲料转化率提高9.95%;每公斤增重饲料成本降低9.2%。     

第一批正式转为国家标准的渔药第四部分:调节水生动物代谢及生长的药物

水产养殖者为了提高饲料转换率,常在饲料中添加一些能调节代谢和促进生长的药物,这些添加剂要求不危害人和动物的健康,一般不具有诊断和治疗疾病的作用,大多用作改进饵料利用率.目前在养殖生产中常用的调节水生动物代谢及生长的药物主要有矿物质、维生素、氨基酸、脂质、激素、酶制剂等几大类.     

酶制剂在水产养殖饲料中的应用

1 酶制剂(酶、酵素)的概念 酶制剂是由一种或多种可以分解饲料营养分子链的生物活性物质组成的微量添加剂.它可降解饲料中各营养组分的分子链,或者改变动物消化道内酶系的组成,促进消化,大幅度提高饲料效率,促进动物生长.酶制剂的探索性应用已有多年,但是作为商品酶制剂应用到实际生产上只是近年的事.     

酶制剂在水产业的应用及发展前景

酶制剂一般是指由特异微生物生产的外源酶制剂。按所包括的种类可分为复合酶及单种酶,按酶所作用的对象又可分为植酸酶,糖酶,蛋白酶等。现在酶制剂已被广泛应用到畜禽日粮中去,但在水产业的应用却不多,本文拟就酶制剂在水产业的应用及发展前景作一番简述。１　酶制剂在水产业的应用１１　可根据鱼类内源酶活性的相关因素相应添加酶制剂,提高饲料的消化率,分解毒素因子。鱼类本身的消化酶的活性与鱼类的生态、食性、成长阶段和饲料组成都有着密切的关系。因此可根据不同因素有针对性地适量添加酶制剂。普通杂食性鱼类饲料也含有相当…     

饲用酶制剂受到关注的原因分析

酶是蛋白质催化剂,生物的各种生理现象几乎都与酶的作用分不开,被誉为生命活动的“推动机”。没有酶的催化作用,任何生物工程技术都是不能实现的。饲用酶制剂目前已引起养殖业和饲料工业的特别重视。近30年来,有关酶的技术发展很快。酶制剂作为生物催化剂,已经在工业和医药等领域显示了非常重要的作用;最新的饲用酶制剂的研究和应用更为酶技术的广泛使用展示了辉煌的前景。饲用酶制剂作为饲料添加剂的一个全新品种,得到饲料工业和养殖行业的普遍重视和广泛应用。饲用酶制剂为什么会受到如此的关注呢？其主要原因是：一、饲料资源短缺…     

日粮中添加酶制剂对肉兔生长性能的影响

为研究日粮中添加饲用酶制剂对新西兰肉兔生长性能的影响,特进行本试验。选择60只30日龄断奶新西兰兔按窝配对分为3组,C组为对照组,T1组和T2组日粮中分别添加0.8%和0.15%饲用复合酶制剂,测定各组日增重、日耗料、饲料转化率。结果表明:肉兔日粮中加入适量的酶制剂可以提高肉兔的日增重和饲料转化率,降低生产成本;酶制剂的剂量以0.15%效果较好,0.8%的酶制剂剂量似有些过量。     

Vulnerability of the biota in riverine and seasonally flooded habitats to damming of Amazonian rivers

1. The extent and intensity of impacts of multiple new dams in the Amazon basin on specific biological groups are potentially large, but still uncertain and need to be better understood.
2. It is known that river disruption and regulation by dams may affect sediment supplies, river channel migration, floodplain dynamics, and, as a major adverse consequence, are likely to decrease or even suppress ecological connectivity among populations of aquatic organisms and organisms dependent upon seasonally flooded environments.
3. This article complements our previous results by assessing the relationships between dams, our Dam Environmental Vulnerability Index (DEVI), and the biotic environments threatened by the effects of dams. Because of the cartographic representation of DEVI, it is a useful tool to compare the potential hydrophysical impacts of proposed dams in the Amazon basin with the spatial distribution of biological diversity. As the impact of Amazonian dams on the biota of both rivers and periodically flooded riparian environments is severe, DEVIs from different Amazonian tributary basins are contrasted with patterns of diversity and distribution of fish, flooded forest trees and bird species.
4. There is a consistent relationship between higher DEVI values and the patterns of higher species richness and endemism in all three biological groups. An assessment of vulnerability at the scale of tributary basins, the assessment of biodiversity patterns related to DEVI, and the analysis of teleconnections at basin scale, demonstrate that recent construction of dams is affecting the biota of the Amazon basin.
5. The evidence presented here predicts that, if currently planned dams are built without considering the balance between energy production and environmental conservation, their cumulative effects will increase drastically and represent a major threat to Amazonian biodiversity.

     

The Kaikōura earthquake in southern New Zealand: Loss of connectivity of marine communities and the necessity of a cross‐ecosystem perspective

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Our previous studies on the effect of stress on pubertal development in carp have shown that repeated temperature changes caused an increase in cortisol levels and a retardation of the first waves of spermatogenesis. Identical effects, accompanied by a decrease in 11-ketotestosterone (11KT) plasma levels and the gonadosomatic index (GSI) were induced by cortisol administration via cortisol containing food pellets. The decrease in plasma 11KT is caused by a direct effect of cortisol on the steroid producing capacity of the testis, independent of luteinizing hormone (LH) levels. However, the mechanism through which cortisol interferes with testicular steroidogenesis is unknown. In the present study, we showed that in vitro physiological levels of cortisol can inhibit the conversion of 11β-hydroxyandrostenedione (OHA) into androstenetrione (OA), which is the precursor of 11KT, possibly by competing for the enzyme 11β-hydroxysteroid dehydrogenase (11β-HSD). The same mechanism may occur in vivo. However, our results demonstrate that an elevation of plasma cortisol levels during acute cortisol treatment did not result in lower plasma levels of OA and 11KT, but we did observe an accumulation of OHA. We suggest that the previously observed decrease in 11-oxygenated androgens, as an effect of long-term cortisol treatment, is caused by a retardation of testicular development. This results in a lower steroid synthesizing capacity of the testis as a whole. Although the in vitro observed cortisol inhibition of the conversion of OHA into 11KT plays a role in the accumulation of OHA, it apparently has no effect on the final 11KT plasma concentration. This revised version was published online in August 2006 with corrections to the Cover Date.     

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Abstract –  A model based on proximate considerations of life histories of Atlantic salmon, Salmo salar , was examined for its applicability to fit the variation in life-history of wild Arctic charr, Salvelinus alpinus , based on a qualitative assessment of information related to growth and lipid dynamics of Arctic charr. The original salmon model is discussed in context of modifications required to account for added complexities in the life history of Arctic charr in relation to anadromy versus residency. A study from North Norway shows that individual charr that emigrate from the lakes to the sea, maintain a high growth rate in the lake in late summer and early autumn compared with resident fish. Their relatively low lipid level in autumn combined with a high rate of change of lipid during winter was associated with postponement of maturation in the anadromous individuals. Individuals that remain resident in the lake arrested growth in autumn. Their high lipid level in autumn combined with a low rate of change of lipid during winter was associated with maturation the following summer, without emigration from freshwater. Results from this and other related studies show similarities with the model derived from lipid and growth dynamics of Atlantic salmon. The adjusted charr model illustrates possible proximate explanations for the high variation in life-history strategies of Arctic charr. However, the model does not account for the characteristic return migration of immature charr into freshwater several weeks after their entry to the sea. The proximate physiological stimulus for this movement of immature fish is not entirely clear.     

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The elucidation of the molecular structure of salmon growth hormone (GH) in the mid-1980's paved the way for a new era of endocrinological research. Establishment of homologous immuno- and receptor-assays have made studies of the secretion, tissue and plasma GH levels, GH turn-over and GH receptor concentrations possible. This overview attempts to summarize the present understanding of the biological roles of GH in salmon. Although the involvement of GH in the regulation of physiological processes throughout the salmon life history has yet to be comprehensively explored, the hormone has already been demonstrated to have several important functions. GH is a principal regulator of somatic growth in salmonids. The growth-stimulating effect of GH is probably integrated with that of insulin-like growth factor I (IGF-I), as in later vertebrates. GH stimulates protein synthesis and improves feed conversion during growth. The hormone also promotes lipid and glycogen breakdown as well as gluconeogenesis, functions which are probably of great importance during starvation when GH levels are seen to increase. During parr-smolt transformation of anadromous salmonids, circulating GH levels appear to be governed by environmental cues. Increasing springtime daylength elevates GH levels, and temperature modulates the photoperiod regulation of GH. The seawater-adapting role of GH during the parr-smolt transformation is complex. In freshwater, GH improves hypoosmoregulatory ability by stimulating branchial Na⁺,K⁺-ATPase activity and probably also acts in kidney and intestine. Following seawater entry, GH levels and turn-over increase transiently, probably to further increase seawater tolerance. Accumulating in vitro and in vivo data support the conclusion that GH is involved in the regulation of sexual maturation in salmonids although further studies are needed to establish the exact role of GH in this process. GH increases appetite but it is unclear whether the hormone effects the central nervous system directly, or acts indirectly through metabolic changes. GH increases swimming activity as well as dominant feeding behaviour and diminishes anti-predator behaviour of juvenile salmonids. The GH-induced changes of behavioural patterns imply that there exists an ecological trade-off between high growth rate and long-term survival which may explain why natural fish populations normally grow at sub-maximal rates. Current knowledge indicates that GH is an important and multi-functional hormone in salmon and a central mediator of seasonal changes in physiology and behaviour. The regulatory effects of GH are also of great applied interest as they are likely to affect both product quality in aquaculture and long-term survival of released fish.     

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