Low-protein supplement increases protein retention and reduces the amounts of nitrogen and phosphorus wasted by rainbow trout fed on low-fat herring

The growth, food utilization and amounts of nitrogen and phosphorus lost into the water by rainbow trout (initial size 485 g) fed on low-fat Baltic herring and supplemented with a low-protein dry diet fed separately were studied in an 18-week net cage trial. Similarly to balancing protein and nonprotein energy in full diets, giving nonprotein energy in different feeds several hours apart improved the protein retention of low-fat herring to a level comparable to a commercially available dry diet control. The amounts of nitrogen and phosphorus lost into the water were also reduced to the same extent. The losses from the plain herring-feeding were twice as high. The improved protein retention and reduced nutrient losses were accompanied by 15–25% reductions in growth of the fish compared with the control dry diet. The growth of the fish fed on plain herring was 14% lower than the growth on the dry diet control.     

授粉方式对板栗胚胎发育的影响

为研究受精对板栗胚胎发育的影响,以“遵玉”品种10年生树为试验材料,通过控制授粉试验,观察不同授粉处理板栗胚珠、总苞和子房的形态发育及其氮素和碳水化合物含量的变化趋势。结果表明,受精不良导致空苞的产生,人工授粉板栗空苞率为0%,自然授粉板栗空苞率为12.37%,不授粉板栗空苞率为100%。在板栗果实发育早期,不授粉板栗与人工授粉、自然授粉板栗的胚珠大小、总苞和子房外观形态及碳水化合物含量变化差异不显著,但其氮素含量显著小于其他2个授粉处理板栗;授粉后16 d,正常发育胚珠大小显著大于发育异常胚珠,此时人工授粉、自然授粉板栗总苞和子房体积显著大于不授粉的板栗子房,碳水化合物含量差异不显著;幼胚发育期,人工授粉、自然授粉板栗子房可溶性糖、蔗糖和淀粉含量显著高于不授粉板栗子房的含量。     

Tissue and organ distribution of 14C‐activity in dextrin‐adapted Atlantic salmon after oral administration of radiolabelled 14C1‐glucose

Accumulation of ¹⁴C in various tissues and organs was studied in three different groups of 0.8‐kg Atlantic salmon Salmo salar force‐fed with ¹⁴C₁‐glucose in order to evaluate if metabolism of glucose depended on adaptation to dietary carbohydrate level. The salmon had been fed diets supplemented with 0, 100 and 200 g maize dextrin kg^?1 for 10 months before the experiment. The fish were force‐fed 6.65 × 10⁴ Bq of ¹⁴C₁ glucose kg^?1 BW, in gelatin capsules. Fish for analysis were obtained 16 h later. ¹⁴C was measured in blood plasma, gill, kidney, liver and white muscle, and in lipid extract of liver. The liver contained most ¹⁴C, followed by heart, blood plasma, gill and liver lipid extract, while kidney and muscle contained the least ¹⁴C per gram or millilitre tissue. The muscle contained most radioactivity, on an estimated total tissue basis, followed by liver, blood plasma, gill, liver lipid extract, kidney and heart tissue. Thirty‐eight per cent of the orally administered ¹⁴C was recovered in the salmon adapted to the diet without dextrin after 16 h. This was significantly (P < 0.05) higher than the 30% and 32% recovered in the salmon adapted to diets with 10% and 20% dextrin. This effect on adaptation to dietary dextrin level in glucose uptake or metabolism was supported by a trend (P < 0.10) toward higher radioactivity per gram or millilitre of each individual tissue in the fish adapted to the diet without dextrin, when compared with the other two adaptation regimes.     

遮荫对鸡爪槭非结构性碳和化学计量特征的影响

为了探究鸡爪槭（Acerpalmatum）的光适应生长策略,测定并分析了不同光照强度（CK、60%光照与40%光照）下鸡爪槭根、枝与叶中非结构性碳积累、分配及其C:N:P化学计量特征。结果表明：随着遮荫程度增加,根的非结构性碳水化合物含量（NSCs）及其组分增大,枝与叶的NSCs及其组分减小,叶N、P含量增大,C:N、C:P减少,枝N含量、N:P先减小再增大,P、C:N和C:P先增大再减小,根N、P含量先增大再减小,N:P、C:N和C:P先减小再增大。在全光照下,NSCs及其组分为叶>枝>根,N含量为叶>根>枝,N:P和C:N为根>叶>枝;60%的光照下,NSCs及其组分为叶>枝>根,N含量与N:P为叶>根>枝,C:N与C:P为枝>叶>根;40%光照下,NSCs及其组分根>叶>枝,N、P含量为叶>枝>根,C:N与C:P为根>枝>叶。相关性分析表明,叶可溶性糖、淀粉、NSCs含量与N、P含量呈显著负相关,与C:N和C:P呈显著正相关（P <0.01）;枝NSCs含量与N和C:...     

倒伏发生对燕麦籽粒灌浆进程及非结构性碳水化物的影响

为探讨倒伏发生对高寒区燕麦（Avena sativa L.）产量形成产生的影响,本试验在灌浆期选择长势和表观倒伏率基本一致的6份燕麦材料,分析倒伏和未倒伏植株燕麦籽粒千粒重、含水量及非结构性碳水化合物形成规律。结果表明,燕麦籽粒灌浆速率随灌浆进程呈先增后降的变化趋势,倒伏燕麦籽粒灌浆进程较对照（未倒伏）变缓,其灌浆速率和生长速率分别较未倒伏植株籽粒低17.94%和10.49%;倒伏显著（P<0.05）影响籽粒千粒重、含水量、可溶性糖和淀粉含量;倒伏发生后成熟期燕麦籽粒的千粒重、可溶性糖和淀粉含量平均较对照分别降低9.80%、33.58%和3.89%;倒伏对不同燕麦材料的影响程度不同,成熟期对‘青永久125’、‘青永久380’和‘青永久787’千粒重影响较大,分别较对照降低10.55%、10.23%和9.94%;对‘青永久402’和‘青永久380’淀粉含量影响较大,分别较对照降低6.86%和4.24%,对‘青永久402’、‘青永久787’和‘青永久993’可溶性糖含量影响较大,分别较对照降低46.79%、39.67%和38.43%。可见,灌浆期倒伏是燕麦籽粒产量和品质降低的主要因素,在燕麦育种中应加强抗倒伏型品种的选育。     

甘蔗叶片中转化酶的变化规律及其与生长和糖分积累的关系

本试验以中早熟高糖品种川蔗10号和迟熟低糖品种海蔗5号为材料,研究甘蔗叶片中转化酶的变化规律及其对甘蔗主要性状的影响。结果表明,叶片中转化酶活力与生长呈正相关,而与糖分积累呈负相关。成熟期较高的酸性转化酶活力对糖分积累不利。不同类型品种转化酶转化模式不同,反映了它们遗传型的差异。因此,转化酶特别是酸性转化酶可作为甘蔗育种及其基因型选择的显著生理指标。     

Impact of macronutrient composition and palatability in wet diets on food selection in cats

Cats are obligate carnivores adapted to high‐protein diets, but are commonly fed diets rich in carbohydrate. The aim of this study was to examine the food intake choices of cats when diets with different protein and carbohydrate contents were offered. Thirty‐nine cats participated in voluntary dietary intake studies. Four foods were formulated to provide between 24% and 53% of metabolizable energy as protein, between 43% and 11% as carbohydrate and holding dietary fat constant with a contribution of approximately 36%. Foods were offered either singly to evaluate voluntary food intake or in pairs to compare food intake between pairs of diets. Cats regulated their macronutrient intake to attain an overall diet composition that provided 53% of metabolizable energy as protein, 11% as carbohydrate and 36% as fat. The protein contribution corresponded to approximately 6 g of protein/kg body weight/day. High‐protein/low‐carbohydrate diets were always eaten preferentially over low‐protein/high‐carbohydrate foods. When low‐protein/high‐carbohydrate diets were offered, cats limited their food intake to limit daily carbohydrate intake to less than 3 g of carbohydrate/kg body weight. This carbohydrate ceiling may limit protein and even energy intake when only low‐protein/high‐carbohydrate diets were offered. The inclusion of palatability enhancer in the diets increased food intake but did not change protein or carbohydrate intake patterns, indicating that macronutrient intake can be regulated regardless of the use of palatability enhancers in cats. We conclude that cats can discriminate between diets based on macronutrient composition and regulate their intake to maintain maximal protein intake but limit carbohydrate intake.     

Effects of dietary carbohydrate sources on plasma glucose, insulin and IGF-I levels in multiparous sows

Effects of different carbohydrate sources on plasma glucose, insulin and insulin-like growth factor-I (IGF-I) levels were compared to subsequently be able to study effects of insulin-stimulating diets on follicle development in sows. The following feed components were tested in 12 sows during six consecutive test periods of 9.5 days: dextrose (DEX), sucrose (SUC), lactose (LAC), dextrose plus lactose (DL), sucrose plus lactose (SL), dextrose plus sugarbeet pulp (DSBP) and control (CON). On day 2, 5 and 9 of each test period, plasma glucose (only at day 9), insulin and IGF-I profiles were determined. Despite similar glucose profiles for all diets, the postprandial insulin response was higher for DL and SL compared with CON and LAC; the other diets were intermediate. Plasma IGF-I levels were higher in CON, LAC and SL compared with DSBP, but differences were only marginal. It was concluded that dextrose and sucrose have the potential to stimulate fast and high insulin peaks, especially when combined with additional lactose. Despite the high dextrose in the DSBP diet, the insulin response was flattened, probably due to the viscosity of sugarbeet pulp. The results show that modulation of plasma insulin levels by dietary carbohydrates seems possible in anabolic sows, but IGF-I levels are less easily modified.     

刈割对牧草贮藏碳水化合物含量变化的影响

１９９３年在内蒙古典型草原研究了７种主要牧草的再生性，以及刈割对牧草贮藏碳水化合物含量变化的影响。结果表明，７种牧草的再生性不同。刈割后１５ｄ内，不同牧草以及同一种牧草在不同生长阶段，贮藏碳水化合物含量动态不同。总糖含量主要有３种类型：（１）减少—增加—减少；（２）增加—减少—增加；（３）减少—增加—增加。还原糖含量变化有时与总糖一致，有时则相反。