Effects of Dietary Carbohydrate Source and Level on Growth,Feed Utilization,and Body Composition of the Humpback Grouper,Cromileptes altivelis (Valenciennes)

Six diets were formulated to contain corn starch, tapioca starch, or dextrin at 10% and 20% inclusion levels and fed to humpback grouper fingerlings to apparent satiation for 10 weeks. Growth and feed utilization efficiency of humpback grouper were not affected by dietary carbohydrate source and level. Only slightly higher growth was observed in fish fed 20% dietary carbohydrate compared to the fish fed 10% carbohydrate irrespective of carbohydrate source. Body indices and whole body proximate composition of fish in the present study were generally independent of diet, except that muscle lipid of fish fed diets with 7.6% lipid and 20% carbohydrate was significantly lower than the other groups. In view of the lower price and local availability of tapioca starch compared to corn starch and dextrin, tapioca starch is the preferred source of starch in practical diets for humpback grouper.     

甘露寡糖对高糖饲喂下尼罗罗非鱼肌肉品质的影响

甘露寡糖是一种新型饲料添加剂,它具有保护肠道健康和降血糖的功能。然而,甘露寡糖对于鱼类肌肉品质的影响并无系统性报道。为此,本实验选择均重为2g左右的健康尼罗罗非鱼幼鱼315尾,随机分成对照组（Control,糖含量为35%）、高糖处理组（HC,糖含量为45%）和高糖饲料中添加甘露寡糖处理组（HM,糖含量为45%,甘露寡糖添加量为0.5%）,每组3缸,每缸35尾,投喂10周后,测定其生长指标、肌肉营养成分和质构特性等相关指标。结果显示,与对照组相比,HC组尼罗罗非鱼肝体比,肌肉内聚性,肌纤维数量、肌苷酸含量、鲜味氨基酸占比、支链氨基酸/芳香族氨基酸比例、甘油三酯含量以及可促进肌肉生长的钙蛋白酶抑制蛋白基因CAST 相对表达量均显著升高;肌肉硬度、胶着性、咀嚼性、肌纤维直径、蒸煮损失,必需氨基酸占比以及在肌纤维的分化中起着重要作用的MyoG基因 相对表达量以及脂肪酸、甘油二酯和磷脂酰肌醇含量显著降低。与HC组相比,HM组尼罗罗非鱼的肌肉弹性、必需氨基酸占比,脂肪酸和甘油二酯含量以及CAST基因相对表达量显著增加;肌肉粘力、肌纤维数量、肌苷酸含量,磷脂酰乙醇胺和磷脂酰胆碱含量以及MyoG基因相对表达量均显著降低。与对照组相比,HM组尼罗罗非鱼增重率和肌肉内聚性,支链氨基酸/芳香族氨基酸比例,甘油三酯和脂肪酸含量显著增加;肝体比,肌肉硬度、咀嚼性以及磷脂含量均显著降低。上述结果表明,高糖饲喂可以使罗非鱼肌肉的保水能力增强,其肌肉更嫩更柔软紧密,提升肌肉鲜味,但会降低氨基酸营养价值。在添加甘露寡糖后,可以促进尼罗罗非鱼生长,提高产肉率和肌肉持水力,并且肌肉更加柔软紧密且富有弹性,提高氨基酸营养价值,但是会降低磷脂含量。     

氮肥运筹对四川丘陵旱地带状种植小麦碳素同化、运转和产量的影响

为探讨四川丘陵旱地氮肥运筹对带状种植小麦碳素同化、运转和产量的影响,以川麦42号为材料,研究不同施氮量和施氮方式对带状种植小麦植株非结构性碳水化合物(NSC)的同化和转运的影响。结果表明:施用氮肥能有效提高花后旗叶叶绿素含量,促进花后NSC的累积,提高其对籽粒NSC的贡献率,但是过量施氮不利于茎鞘中可溶性糖(WSC)向籽粒的转运,同时花后NSC积累量及其对籽粒NSC的贡献率降低,不利于籽粒中NSC的累积;氮肥分次施用能显著提高花后旗叶叶绿素含量,促进花后NSC的累积,提高花后NSC对籽粒NSC的贡献率,尤以拔节期追施效果最佳。本试验条件下,施氮量为135～180kg/hm2、施氮方式为底肥∶拔节肥=7∶3时,小麦花后旗叶叶绿素含量较高,并能维持较长的高值持续期,花后NSC积累量增加,且其对籽粒NSC的贡献率提高,籽粒中NSC积累量增加,产量最高。     

光周期对黄瓜幼苗形态、光合特性及碳水化合物含量的影响

为探究光周期对黄瓜幼苗形态、光合特性及碳水化合物含量的影响,在光强为250 μmol/（m²·s）的白光下,设置光周期为8 h/16 h、12 h/12 h、16 h/8 h和20 h/4 h共4个处理,比较各处理对黄瓜幼苗的影响。结果表明：不同光周期处理后的黄瓜幼苗形态差异较大,其株高、茎粗、鲜重、干重与叶面积均发生显著性差异,12 h/12 h处理下株高、茎粗和总叶面积均显著优于其余处理;随着光周期的增加,叶片各组织厚度增加,Rubisco酶活性呈现下降趋势,8 h/16 h处理较16 h/8 h与20 h/4 h处理显著增加66.23%和82.86%;黄瓜幼苗总氮含量随着光周期的增加呈现显著下降趋势;12 h/12 h处理下总碳含量显著高于8 h/16 h和20 h/4 h;12 h/12 h和16 h/8 h处理的淀粉含量显著高于其余处理。综上,12 h/12 h处理为黄瓜幼苗生长的最适宜光照周期。该研究结果可为植物工厂化育苗及设施内补光提供依据和参考。     

错株种植对密植夏玉米碳氮分配的影响

为探明错株种植方式对黄淮海地区密植夏玉米植株碳氮代谢的调控作用,以‘郑单958’为材料,设置6.75万（D₁）、8.25万（D₂）和9.00万株/hm²（D₃）3个密度水平,错株（S）和对株（CK）种植2种方式,测定植株氮素（N）和非结构性碳水化合物（NSC）的积累量、花前转运量、花前转运效率、花前转运对籽粒的贡献率、花后积累量以及收获指数。结果表明：1）增加种植密度可显著提高植株N和NSC的积累量、花前转运量和花后积累量,但降低了N和NSC转运效率及其对籽粒的贡献率（P<0.05）;过高密植水平（D₃）不利于籽粒中碳氮的积累和转运;其中,碳氮积累和转运量以D₂最高。2）错株种植（S）可显著增加夏玉米植株N和NSC的积累量,促进N和NSC花前的转运和花后的积累,并可显著提高花前N和NSC转运效率（P<0.05）。3）在各处理组合中,D₂S的N和NSC积累量、花前转运量和花后积累量均显著高于其他处理（P<0.05）,且D₂S的N和NSC转运效率及其对籽粒的贡献率与对照（D₁CK）相比并未显著下降。综上,黄淮海地区夏玉米在8.25万株/hm²密植（D₂）水平下采取错株（S）种植方式可显著提高整株的氮素和非结构性碳水化合物的积累,并促进其向籽粒的转运,获得较高的N、NSC收获指数和产量。     

Effects of different carbohydrate levels in puffed feed on digestive tract morphological function and liver tissue structure of snakeheads (Channa argus)

The major objective of this study conducted for 8 weeks was to investigate the influence of different carbohydrate levels in the feed on the digestion and tissue structure of snakeheads (Channa argus) with prolonged feeding time. The control (CT) group was fed chilled fish, and the experimental groups were fed flour as a carbohydrate source to prepare puffed feed containing 13%, 16% and 19% flour (WS13, WS16 and WS19 respectively). The results demonstrated that carbohydrate levels in the feed had significant effects on amylase activity in the intestinal segment and Na+, K+‐ATPase activity in the stomach (p < .05). In all the experimental groups, the pepsin activity in the gastrointestinal tract showed a decreasing trend over time in different feeding cycles. The alkaline phosphatase (AKP) activities in all groups showed a downward trend, and with increased feeding time, AKP in all experimental groups had an increasing trend. The liver index, liver crude fat content and serum triglyceride of snakeheads increased significantly with the increase in carbohydrate content in feed at 4 weeks (p < .05). There were no differences in the stomach structure among the groups as determined using light microscopy. The intestinal villi were injured, and the liver cells became larger and showed damage in a time and carbohydrate level‐dependent manner. In conclusion, when the carbohydrate content is too high, it not only affects the morphological function of the snakeheads' digestive tract, but also affects the normal structure of liver cells and the metabolic function of the liver.     

Is dormancy breaking of potato tubers the reverse of tuber initiation?

Summary Tuber formation is a well orchestrated physiological event that involves many metabolic changes. Dormancy gradually develops in potato tubers from the moment cell division in the stolon tip has stopped and the tuber starts to develop. Dormancy breakage may be the reverse of dormancy initiation suggesting that there may be similarities between tuber induction and dormancy development. Based on a literature review it is concluded that, when comparing tuber induction and the breaking of dormancy, hormonal activities are only partly reversed, whereas carbohydrates and enzyme activities might be reversed. For more definite conclusions more research should be done to assess precisely the moment of dormancy breaking. Moreover, measurements on events associated with tuber induction and dormancy breaking should be carried out using the same techniques and the same material. Molecular genetic analyses may provide well-defined markers for the timing of breaking of dormancy.     

饲粮非纤维性碳水化合物/中性洗涤纤维对肉犊牛生长性能和营养物质消化代谢的影响

本试验旨在研究饲粮非纤维性碳水化合物/中性洗涤纤维(NFC/NDF)对断奶肉犊牛生长性能、血清生化指标和营养物质消化代谢的影响。选取2~3月龄健康、平均体重为(94.38±0.25)kg的断奶肉犊牛60头,随机分为4组,每组15头。分别饲喂粗蛋白质水平相近,NFC/NDF分别为1.35(A组)、1.23(B组)、0.94(C组)和0.80(D组)的4种全混合日粮。试验期105 d,其中预试期15 d,正试期90 d。每日测定采食量,每隔15 d测量犊牛的体重;于15、30、45、60、75和90 d颈静脉采血测定血清葡萄糖(GLU)、生长激素(GH)、胰岛素样生长因子-Ⅰ(IGF-Ⅰ)、瘦素(LEP)、胰岛素(INS)、胰高血糖素(PG)和甘油三酯(TG)的浓度;分别在30和90 d时以全收粪尿法进行消化代谢试验。结果表明:1)高NFC/NDF饲粮提高了犊牛的平均日增重,A组显著高于其他3组(P0.05);2)A组血清LEP浓度显著高于C组和D组(P0.05),D组血清IGF-Ⅰ浓度显著高于其他各组(P0.05);3)90 d时,干物质、中性洗涤纤维和酸性洗涤纤维的表观消化率及总能消化率、总能代谢率和消化能代谢率随饲粮NFC/NDF的降低而降低,A组均显著高于D组(P0.05),D组甲烷能显著高于其他组(P0.05),A组尿能、尿氮和消化氮显著高于B组和C组(P0.05)。综上所述,NFC/NDF为1.35的饲粮可以满足3~6月龄肉犊牛对营养物质的需求,采食该饲粮不但可以使肉犊牛保持较高的平均日增重(1.14 kg/d),而且此饲粮易消化利用,采食后相关血清生化指标均在正常范围内,并未影响犊牛健康。