Optimizing the Proportions of Plant Protein Ingredients in the Diet of Juvenile Blunt Snout Bream,Megalobrama amblycephala

An 8‐wk feeding trial was conducted to evaluate the influence of different proportions of dietary plant ingredients on the growth of juvenile blunt snout bream, Megalobrama amblycephala. A 2 × 3 factorial arrangement was set for this trial with three ratios of cottonseed meal (CSM) and canola meal (CM) (2:1, 1:1, or 1:2) and three proportions of soybean meal (SBM) (2, 1, or 0). The results showed that the specific growth rate and protein efficiency ratio both significantly decreased with decreasing amounts of SBM in the diets of blunt snout bream (P < 0.05), while the feed efficiency ratio and feed intake increased significantly (P < 0.05). Meanwhile, the growth performance and feed utilization were shown to improve with increasing amounts of CSM, although the effects were not significant (P > 0.05). The interaction of these two factors had no effect on either growth or feed utilization (P > 0.05). Diet composition was not seen to affect body composition (P > 0.05). The ratio of CSM to CM significantly affected gut amylase activity, liver alanine aminotransferase content, and plasma cholesterol levels (P < 0.05). The interaction between the two main effects significantly influenced the plasma glucose level (P < 0.05). Therefore, the suitable proportion of plant feed for blunt snout bream should include high levels of SBM and CSM, with a SBM : CSM : CM ratio of 2:2:1.     

苏粳815机插高产形成特点及其配套精确定量栽培技术

通过综合高产试验和机插行株距规格与氮肥组合试验,分析了苏粳815高产形成的特点,明确了其高产产量结构及其形成的主要生育指标,提出了目标产量650~700 kg/667 m~2相配套的精确定量栽培技术。     

沅水银鮈年龄与生长的研究

基于2016年3月至2017年3月采自沅水支流無水的137尾样本,使用耳石和鳞片为年龄鉴定材料,对银鮈(Squalidus argentatus)的年龄结构和生长特征进行了研究。结果显示:研究样本体长范围为40~115 mm,优势体长组为60~100 mm(占86.1%);体重范围为1.1~23.6 g,优势体重组为3~12 g(占77.4%);共4个年龄组,1龄和2龄为优势年龄组(占93.2%)。体长和耳石半径为直线正相关,L=-9.062+258.896×R(n=132,r2=0.773);体长-体重关系方程为:W=8.557×10~(-6)×L3.134(r2=0.974,n=137),银鮈为异速生长鱼类;以退算体长拟合的von Bertalanffy方程为:Lt=177.7(1-e-0.235(t+0.193))(r2=0.909),Wt=96.1(1-e-0.235(t+0.193))3.13。估算的拐点年龄为4.7龄,对应的体长体重分别为120.9 mm和28.7 g。研究表明耳石是银鮈较好的年龄鉴定材料。沅江银鮈的年龄结构趋于简单,面临较大的捕捞压力,渔业主管部门应为保护其种质资源制定相应的措施。     

Freshwater nucleated pearl quality is influenced by host mussel growth traits in Hyriopsis cumingii

Hyriopsis cumingii is one of the most important freshwater pearl mussels in China. Recently, this species can produce freshwater nucleated pearls of high quality. Here, we investigated whether nucleated pearl quality is influenced by the growth traits of the host mussel or other factors like cultivation period. We implanted host mussels with a spherical nucleus consisting of a small piece of mantle tissue from donor mussels. After 24 and 36 months of culture, host mussel growth traits including body weight and shell length, height, width and weight were recorded. These factors were then correlated with the quality traits of the pearls they produced, such as nacre thickness, size, weight, lustre and colour. Results indicated pearls obtained at 36 months after seeding were significantly larger in terms of nacre thickness, size and weight compared to those harvested at 24 months. In particular, nacre thickness (r = 0.33–0.48, P = 0.00), pearl size (r = 0.39–0.43, P = 0.00) and pearl weight (r = 0.35–0.47, P = 0.00) were showed to be significantly correlated with host mussels shell length, body weight and shell weight at 24 or 36 months. Larger and heavier host mussels tended to produce bigger pearls. In contrast, host mussels did not affect pearl colour. Cumulatively, our results suggest that longer culturing times and a larger host mussel may help produce better quality nucleated pearl. This information can help guide selective breeding programs designed to improve pearl quality produced by H. cumingii.     

不同氮肥水平下蚯蚓粪施用对水稻生长特性及产量的影响

以两优培九为材料,采用大田微区试验,研究不同氮肥水平(N1,9 g/m~2;N2,12 g/m~2;N3,15 g/m~2)下不同蚯蚓粪施用量(EC0,0;EC_1,16.88 kg/m~2;EC_2,33.76 kg/m~2)对水稻生长及产量形成的影响。结果表明,移栽40 d后EC_2和EC_1处理的茎蘖数均显著高于EC0(P0.05);幼穗分化期和乳熟期EC0处理的SPAD值均显著低于EC_1和EC_2处理(P0.05);齐穗期EC0处理的叶面积指数分别比EC_1和EC_2处理低32.7%和80.7%,地上部总干物质量分别比EC_1和EC_2处理低30.6%和59.8%;成熟期有效穗数、地上部干物质量和水稻产量均表现为EC_2EC_1EC0,EC_2和EC_1处理的有效穗数分别比EC0处理多41.5%和21.3%、地上部干物质量分别比EC0处理高47.7%和25.8%、产量分别比EC0处理高35.4%和34.3%。由此可见,施用蚯蚓粪便可促进水稻分蘖,提高水稻叶面积、SPAD值和地上部干物质量,进而提高水稻籽粒产量。     

Effects of dietary protein to energy ratios on growth,body composition and digestive enzyme activities in Chinese mitten‐handed crab,Eriocheir sinensis

This study aimed to determine the optimal protein to energy ratio (P/E ratio) and evaluate the effect of dietary protein and lipid levels on growth performance, body composition and digestive enzymes activities in Chinese mitten‐handed crab, Eriocheir sinensis. Nine practical diets containing three levels both for protein (DP 30%, 35% and 40%) and lipid (DL 2%, 7% and 12%) with P/E ratios ranging from 13.69 to 19.79 mg KJ^?1 were fed to four replicates of crabs (3.39 ± 0.10 g) for 10 weeks. Weight gain increased significantly with the increase in DP level at each DL level. Moreover, weight gain increased in crabs fed with diets containing DL level from 2% to 12% and DP level from 30% to 35%. However, the diet containing 40% DP and 12% DL levels significantly decreased the growth performance and protein efficiency of the crabs. The whole crab and hepatopancreas lipid contents also increased as dietary lipid increased, but not dietary protein. The total protease activity increased significantly with the increase in dietary protein at each lipid level. The lipase activity was statistically comparable among different DL levels at each DP level. Taken together, the crab fed the diet containing 35% protein and 12% lipid levels with P/E 15.77 mg KJ^?1 revealed optimal growth, feed utilization efficiency and digestive enzymes activities. Moreover, our study indicated that the higher dietary lipid level at a relatively lower dietary protein level could provide protein sparing effect in Eriocheir sinensis.     

Effects of adding sucrose on Penaeus monodon (Fabricius, 1798) growth performance and water quality in a biofloc system

A 60‐day indoor growth trial was conducted to study the effects of biofloc on the growth performance of a Penaeus monodon (Fabricius, 1798), water quality and biological indicators including biofloc volume, chlorophyll‐a, heterotrophic bacteria and Bacillus quantity. Two concentrations of sucrose (0 and 75%) were added daily to the P. monodon culture systems (2.94 ± 0.11 g), which were conducted indoors in fibre‐glass tanks (500 L). Results showed that the final body weight and weight gain of the adding 75% sucrose group were significantly higher (P < 0.05) than that of the control, as well as significantly (P < 0.05) improved specific growth rates and survival rates, and reduced feed coefficient. Adding 75% sucrose promoted heterotrophic bacteria, Bacillus and phytoplankton reproduction, and significantly (P < 0.05) reduced the concentration of ammonia‐N (NH₄‐N), nitrite‐N (NO₂‐N) and nitrate‐N (NO₃‐N). The changes of water quality indicators in the two groups showed the similar trend at the end of the experiment, and the ammonia‐N, nitrite‐N, nitrate‐N and phosphate‐P concentrations in the 75% sucrose group were significantly (P < 0.05) lower than those of the control group, Chlorophyll‐a concentrations peaked at 389.12 μg/L in the biofloc sucrose group at 18:00 h, and heterotrophic bacteria peaked 8 h after sucrose was added. The addition of sucrose also reduced the pH of the water. Our research showed that adding sucrose promoted biofloc formation and shortened the formation time; increased the number of heterotrophic bacteria and algae which might play a role in improving water quality by assimilating ammonia‐N and other harmful substances in the water; supplemented food for P monodon growth; and reduced the feed coefficient.     

北方设施条件下辣木及改良品种生长差异性分析

北方地区利用温室栽培辣木(Moringa oleifera Lam.)及其2个改良品种‘PKM1’和‘PKM2’,通过分析表观生长量、养分含量以及光合特性等指标的差异性,筛选适宜北方温室种植的辣木品种。结果表明:PKM1的高生长和增粗生长均显著快于辣木和PKM2(p0.05),在定干前(71 d)三者平均株高依次为115.7、80.2、81.0 cm,地径依次达17.47、13.27、15.08 mm。植株养分季节变化,PKM1养分状况要优于辣木和PKM2,在5月份,PKM1叶片中全氮(44.32 mg/g)、全钾(12.73 mg/g)含量显著高于其它2个品种(p0.05),全磷和可溶性糖含量品种间无显著性差异;7月份,PKM1可溶性糖显著高于其它2个品种;光合特性分析,3个品种在弱光条件下的光量子利用效率及光补偿能力差异不显著(p0.05),随着光强增加,光量子的转化能力出现显著性差异,PKM1的最大净光合速率(A_(max))显著高于辣木和PKM2(p0.05),最高达23.84μmol CO_2/(m~2·s)。可见,北方设施条件下,PKM1的生长速度、养分状况、光合能力均表现最好,较适宜北方温室栽培。     

Effect of dietary protein content on growth rate,survival and body composition of juvenile cauque river prawn,Macrobrachium americanum (Bate 1868)

We determined the effect of four concentrations of dietary crude protein, 30.7, 37.2, 41.8 and 46.8% on growth rate, survival and body composition of the juvenile cauque river prawn (Macrobrachium americanum). The prawns were hatched in the laboratory from the spawn of one wild ovigerous female. Prawns consuming 37.2% crude protein reached a final weight of 0.58 g (feed conversion ratio of 2.15), which was significantly better than the other treatments. Survival was 100% in all treatments. Protein content in the diets had no significant effect on whole body proximate composition and amino acid profile. Juveniles consuming the 37.2% crude protein diet grew faster than those fed the other diets. Specific growth rate was adjusted to the two‐slope broken‐line regression analysis model to estimate the optimal protein requirement. In conclusion, these results demonstrated that the 37.2% protein level diet is optimal for juvenile cauque river prawn M. americanum in the experimental conditions of this study.     

Growth and economic analysis of freshwater prawn,Macrobrachium rosenbergii (de Man), produced with feeds substituting sunflower cake for fish meal,soya bean meal and mustard oil cake

A feeding trial with Macrobrachium rosenbergii was carried out to test the effectiveness of sunflower cake (SFC) as a replacement for conventional protein sources. Four isonitrogenous (~30% crude protein) and isocaloric (388–402 kcal) diets were formulated. Diet‐1 was a control made with conventional ingredients including fish meal, soya bean meal and mustard oil cake. Diet‐2, Diet‐3 and Diet‐4 were made with 30%, 40% and 50% SFC, respectively, replacing the usual protein sources used in Diet‐1. After 100 days, diets with SFC inclusion showed favourable growth and economic performance trends compared to control diet‐1, but without significant differences (p > .05). Better production (572.89 ± 62.99 kg/ha) was observed with Diet‐4 followed by Diet‐2, Diet‐3 and Diet‐1. Diet‐4 revealed the best feed conversion ratio (2.56 ± 0.24), specific growth rate (1.18 ± 0.05) and protein efficiency ratio (1.14 ± 0.10) among these diets. Whole carcass composition analysis revealed highest crude protein (18.19%) and lipid (4.43%) content in prawns fed Diet‐3 followed by Diet‐4. Highest total income, gross margin and benefit cost ratio (BCR) per hectare from prawns were US$5,759, US$2,623 and 1.84, respectively, found in Diet‐4. This study demonstrates that 30%–50% inclusion of SFC has favourable impacts on productivity and profitability compared with controls, with 50% SFC inclusion as the most cost‐effective diet for prawns without apparent compromise in growth, flesh quality or economics. The performances of the diets suggest that SFC may be a suitable substitute for fishmeal, soya bean meal and mustard oil cake in prawn feed. The effectiveness of higher SFC concentrations should also be investigated.