成年种公马配种期的饲料配方研究

我国马业正在快速发展,但马匹的繁育率低已成为发展过程中的一个难题。因此,进一步提升马匹繁殖能力,加强配种饲养管理已经成为提升马匹繁育率的关键因素之一。为确保饲养出优异的种公马,使其产出更优异的精子。应根据种公马的体况及配种任务,科学给予营养。     

不同热处理DDGS蛋白质营养价值及瘤胃降解特性与其分子结构的相关性研究

试验旨在研究不同热处理干酒精糟及其可溶物(DDGS)蛋白质化学成分、康奈尔净碳水化合物-蛋白质体系(CNCPS)组分、瘤胃降解特性和小肠消化率与蛋白质分子结构的相关性。采用CNCPS、尼龙袋技术及三步体外法对不同热处理的DDGS营养价值进行评定,利用傅里叶变换红外光谱技术(FTIR)分析蛋白质分子结构的变化,进而探求它们之间的相关关系。结果表明:加热使DDGS瘤胃降解率和小肠消化率降低,使小肠可消化蛋白增加;不同热处理对DDGS蛋白质分子结构均有显著影响(P<0.05);蛋白质分子结构中的酰胺Ⅰ和酰胺Ⅱ带的峰高和峰面积、酰胺Ⅰ带和酰胺Ⅱ带峰高和峰面积的比值与DDGS中蛋白质的营养价值、瘤胃降解参数及小肠消化率存在显著相关关系(P<0.05)。可见,不同热处理对DDGS蛋白质分子结构、营养价值和瘤胃降解特性及小肠消化率均有影响,DDGS中蛋白质分子结构可以有效地估测蛋白质营养特性,并可利用FTIR光谱技术对DDGS营养价值及加热程度进行评定。     

Honey Bee (Hymenoptera: Apidae) Nursing Responses to Cuticular Cues Emanating from Short-term Changes in Larval Rearing Environment

Honey bee larvae are dependent on the social structure of colony for their provisioning and survival. With thousands of larvae being managed collectively by groups of foragers (collecting food resources) and nurse bees (processing food and provisioning larvae), coordination of colony efforts in rearing brood depends on multiple dynamic cues of larval presence and needs. Much of these cues appear to be chemical, with larvae producing multiple pheromones, major being brood ester pheromone (BEP; nonvolatile blend of fatty acid esters) that elicits both short-term releaser effects and long-term primer effects. While BEP can affect colony food collection and processing with the signaling of larval presence, it is unclear if BEP signals individual larval needs. To understand this aspect, in a series of experiments we manipulated larval feeding environment by depriving larvae from adult bee contact for 4-h period and examined (1) nurse bee interactions with contact-deprived and nondeprived larvae and larval extracts; (2) forager bee responses to contact-deprived and nondeprived larval extracts. We also characterized BEP of contact-deprived and nondeprived larvae. We found that nurse honey bees tend to aggregate more over contact-deprived larvae when compared with nondeprived larvae, but that these effects were not found in response to whole hexane extracts. Our analytical results suggest that BEP components changed in both quantity and quality over short period of contact deprivation. These changes affected foraging behavior, but did not appear to directly affect nursing behavior, suggesting that different chemical cues are involved in regulating nursing effort to individual larvae.     

Modelling growth and body composition in fish nutrition: where have we been and where are we going?

Mathematical models in fish nutrition have proven indispensable in estimating growth and feed requirements. Nowadays, reducing the environmental footprint and improving product quality of fish culture operations are of increasing interest. This review starts by examining simple models applied to describe/predict fish growth profiles and progresses towards more comprehensive concepts based on bioenergetics and nutrient metabolism. Simple growth models often lack biological interpretation and overlook fundamental properties of fish (e.g. ectothermy, indeterminate growth). In addition, these models disregard possible variations in growth trajectory across life stages. Bioenergetic models have served to predict not only fish growth but also feed requirements and waste outputs from fish culture operations. However, bioenergetics is a concept based on energy-yielding equivalence of chemicals and has significant limitations. Nutrient-based models have been introduced into the fish nutrition literature over the last two decades and stand as a more biologically sound alternative to bioenergetic models. More mechanistic models are required to expand current understanding about growth targets and nutrient utilization for biomass gain. Finally, existing models need to be adapted further to address effectively concerns regarding sustainability, product quality and body traits.     

Egg and larval quality,and egg fatty acid composition of Eurasian perch breeders (Perca fluviatilis) fed different dietary DHA/EPA/AA ratios

In Eurasian perch (Perca fluviatilis), the variability in spawning quality is a major limiting factor for successful production, especially when breeders are fed with an artificial diet. The influence of the dietary DHA/EPA/AA ratio on the egg and larval quality and on the fatty acid and lipid class composition of eggs has been investigated in perch broodstock. Two experimental diets (16% lipids) with two different DHA/EPA/AA ratios, D1 (3/2/2) and D2 (23/9/1), were compared with a natural diet consisting of cultured carp juveniles, CC (10/10/1) and with a commercial diet for salmonids, CDS (14/16/1). Percentages of fertilization and hatching were comparable between fish fed D1, D2 and CC, with the highest hatching rate observed for D1 (63.5 ± 3.8%). These diets supported better values than the CDS. Larval survival and TL50 observed after osmotic stress were higher for the D1 group, followed by larvae produced by fish fed D2 and CC. Larvae from fish fed D1, D2 and CC were significantly more robust than larvae from the CDS group. Differences were observed regarding the fatty acid (FA) profile in the eggs, which was related to the dietary FA composition. The results indicate that a ratio of 3/2/2 seemed to be effective for obtaining eggs and larvae of good quality.     

基于氮稳定同位素分析的三峡水库主要鱼类营养级研究

运用稳定同位素技术对2018年7月—2019年1月采自三峡库区干流木洞、涪陵、云阳和秭归江段的38种鱼类进行氮稳定同位素分析,同时计算鱼类营养级并构建了鱼类连续营养谱。研究结果显示,三峡库区干流鱼类δ15N值平均值为11.02‰,变化范围为5.31‰~17.79‰。以初级消费者螺类作为基准生物估算出三峡库区干流鱼类平均营养级为2.67,范围为1.47~4.12。营养级大于4级的鱼类仅有1种,营养级位于2~3级之间的鱼类种类数最多,占种类总数的50.0%,其次是营养级大于3级的鱼类,占种类总数的31.6%,不同食性鱼类组合的营养级存在差异。库区干流鱼类营养级的时空差异均不显著,而越靠近大坝的江段食物链长度的季节性波动幅度越大。和水库蓄水运行初期相比,鱼类营养级显著升高且高营养级鱼类的群落结构和营养特征发生了一定程度的改变,特别是拥有较高营养级的短颌鲚(Coilia brachygnathus)在库区干流逐渐扩张并成为优势种,其可能对库区干流鱼类营养结构产生影响。     

Real-time RT-qPCR assay to detect sequences in the Piscine orthoreovirus-1 genome segment S1 associated with heart and skeletal muscle inflammation in Atlantic salmon

During the last decade, Piscine orthoreovirus was identified as the main causative agent of heart and skeletal muscle inflammation (HSMI) in Atlantic Salmon, Norway. A recent study showed that PRV-1 sequences from salmonid collected in North Atlantic Pacific Coast (NAPC) grouped separately from the Norwegian sequences found in Atlantic Salmon diagnosed with HSMI. Currently, the routine assay used to screen for PRV-1 in NAPC water and worldwide cannot differentiate between the two groups of PRV-1. Therefore, this study aimed at developing a real-time polymerase chain reaction (RT-qPCR) assay to target the PRV-1 genome segments specific for variants associated with HSMI. The assay was optimized and tested against 71 tissue samples collected from different regions including Norway, Chile and both coast of Canada and different hosts farmed Atlantic Salmon, wild Coho Salmon and escaped Atlantic Salmon collected in British Columbia, West Coast of Canada. This assay has the potential to be used for screening salmonids and non-salmonids that may carry PRV-1 potentially causing HSMI.     

Channel catfish,Ictalurus punctatus,nutrition in the United States: A historical perspective

Although a concerted effort in catfish nutrition research in the United States did not begin until the late 1950s/early 1960s, the genesis of both the catfish industry and catfish nutrition research is rooted in studies conducted early in the 20th century. Thus, a historical view delineating the progression of channel catfish, Ictalurus punctatus, nutrition from 1900 to the present is given. Notable nutrition research programs, as well as significant events and accomplishments, will be examined.     

Measuring fish catch and consumption: Practical methods for small‐scale fisheries based on length as an alternative to weight‐based approaches

Small‐scale fisheries are recognised as making important contributions to nutrition and economic development despite a lack of accurate quantitative information on catches and consumption. While direct measurement remains the most appropriate way of collecting such data, it is impractical at large scales. Instead, household surveys based upon informant recall of fish caught and/or consumed are frequently used. However, the accuracy of weight recall by informants (even over short recall periods) has not been established. Using data from household surveys, the accuracy and precision of catch and consumption estimates derived from: (a) asking informants to recall weights of fish caught and (b) asking respondents to recall lengths of fish caught and converting to weight were tested. Length‐based methods, using visual aids to assist recall, were more accurate, precise and correctable. These methods could be useful for catch estimation, especially where fish are processed, sold or consumed shortly after capture.     

栉孔扇贝Dmrt1的分子鉴定及表达模式分析

DMRT1是DMRT家族重要成员之一,主要参与动物性别决定和分化调控,但在不同动物中其表达和功能调控作用存在差异。本研究采用生物信息学方法分析了栉孔扇贝（Chlamys farreri）Dmrt1的序列特征,采用半定量RT-PCR技术确定了其mRNA在成体性腺、闭壳肌、外套膜、鳃和肾等组织中的分布,定量RT-PCR和原位杂交技术揭示了Dmrt1 mRNA在性腺中的时空表达特征。结果显示：栉孔扇贝Dmrt1序列中含有DMRT家族保守的DM结构域;其mRNA仅在栉孔扇贝性腺中表达,在精巢中的表达明显高于卵巢,并且以生长期精巢的表达水平最高;原位杂交检测Dmrt1阳性信号主要定位于生殖细胞的细胞质中。研究结果表明,Dmrt1在栉孔扇贝性腺中的表达特征与大部分动物性腺中的表达特征基本一致,推测其可能参与性别分化和精巢发育的功能调节。